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By Bruce of Stone Marmot
Progress Energy has requested another rate increase. Among the rates proposed for increase are the category of RS-1: “Customer Charge - $ per line of Billing.” For example, the subcategory of RST-1, “Standard,” is requested to increase from the present $8.03 to $13.21, a 64.5 % increase!
This charge should not even exist at all for the following reasons:
1) It is regressive and hurts the poor far more than the rich. The rich typically use much more electricity than the poor. But since this charge is the same for every user, no matter how much electricity they use, the effective rate per kilowatt hour, that is, the total bill divided by the kilowatt hours used, is much higher for the poor than the rich. Effectively, the poor are subsidizing electricity for the rich, which is backwards from all just logic.
This appears even worse in today’s economy. With so many people losing jobs or forced to take pay cuts, plus many in danger of defaulting on their mortgages, many people are trying to cut costs every way they can just to survive. For these people, every penny saved counts. One way to save is to cut back on electricity use. But the resulting savings are diluted by this big flat charge added to everyone’s bill, no matter how much electricity they use. This charge should be completely eliminated and the rates per kilowatt hour consumed adjusted accordingly so that all customer charges are based directly on the amount of electricity used.
2) It punishes those who conserve energy and rewards the energy gluttons. Again, since this charge is the same for every user, no matter how much electricity they use, the effective rate per kilowatt hour, that is, the total bill divided by the kilowatt hours used, is much higher for those who conserve energy than for those who don’t. Effectively, those who try to be good stewards of our earth’s resources are subsidizing electricity for those who are wasteful and don’t care, which again is backwards from all just logic.
In this age of concern for global warming and talk of carbon footprints and carbon taxes, much of it coming from our own President of the United States and his staff, we should be doing all we can to encourage all people to conserve energy and our resources. One way to do this is by structuring our rates for electricity so that the amount a customer pays is based strictly upon how much they consume. This flat RS-1 charge per customer is counter to this desire. Therefore, this charge should be completely eliminated and the rates per kilowatt hour consumed adjusted accordingly so that all customer charges are based directly on the amount of electricity used.
3) It is effectively a government imposed tax where all the tax revenue is handed directly to a private corporation. Many local governments require a structure to be actively hooked up to the local electrical utility before they will grant an occupancy permit, even if the structure can meet all its electrical needs by some other means, such as solar power. This requirement in itself isn’t just and discourages alternative energy installations. But since many communities have this requirement, and the government also approves all the fees charged by the electrical utility, this flat RS-1 charge per customer is effectively a government imposed tax where all the resulting tax revenue is handed directly to the electrical provider - a private, for profit corporation (and in the case of Progress Energy, one whose headquarters isn’t even located in this state). This is counter to all logic in a just, democratic society.
Progress Energy may argue that it has fixed costs it needs to recover that exist no matter how much electricity is used. This is true of virtually every other business that exists in this country. Yet most all the successful businesses are able to be successful and profitable by including these charges in the cost of their product. Using the logic of the Progress Energy RS-1 charge per customer, are we soon going to be taxed $200 per year per driver, with all the tax revenue handed to the oil companies to partly cover the costs of their wells, refineries, pipelines, etc.? Are we going to be taxed $50 per year per person, with all the tax revenue given to McDonald’s to help cover the cost of all their restaurants?
All Progress Energy customer charges should be strictly based on how much electricity the customer uses. This is the only truly fair way to bill electric power customers. Therefore, the category of RS-1: “Customer Charge - $ per line of Billing,” and all its subcategories of charges, such as RST-1, RSS-1, RSL-1, and RSL-2, should be eliminated and the rates per kilowatt hour consumed adjusted accordingly so that all customer charges are based directly on the amount of electricity used.
To express that you want to eliminate this fixed RS-1 customer charge, please write a letter to the Florida Public Service Commission at:
Director
Division of the Commission Clerk and Administrative Services
Florida Public Service Commission
2540 Shumard Oak Boulevard
Tallahassee, FL 32399-0850
Regards: Docket No. 090079-El
Or call the Florida Public Service Commission at 1-800-342-3552 to register your dissatisfaction with this fixed customer charge.
By Sammy of Stone Marmot
Those of you who frequent this site may have noticed a lot of appearance changes over the past six months. Some things suddenly don’t seem to work, text sizes changed between articles, columns got moved to the bottom, etc. There may be other things that have been happening on other browsers that I’m not even aware of.
I originally created this blog with Wordpress 2.5.1 using a Cutline 3 column theme. It worked pretty well and looked nice. Wordpress 2.5.1 was also fairly easy to use.
Then I started getting notices from Wordpress that I was using an outdated version of Wordpress and that I should upgrade to the latest version. I ignored them since everything was working well. Why fix what isn’t broken?
Then I started getting notices warning me that unless I upgraded, some of my old stuff would stop working. So I looked into upgrading. But the upgrade procedure did not seem too user friendly. Basically, you had to save the entire website, manually remove all but a few critical files from the blog directory (about 99 % of the files, well into the hundreds), and then basically reload Wordpress from scratch, and then somehow associate the handful of files that weren’t removed with the new Wordpress. And to make matters worse, at that time a new version of Wordpress was being released about every week.
But I bit the bullet and upgraded. It took most of a day to do it and to get the blog sort of running again. And, of course, a couple days later they released another update to Wordpress, and a couple more updates since.
But, since the upgrade, I’ve had all sorts of problems. The theme I was using didn’t seem to be working right anymore. So I was forced to upgrade the theme to its latest version. This fixed some problems but introduced other problems. I was able to manually change some of the PHP software files for the theme to fix some of the problems, but not all and some of the problems I fixed would reappear some time later.
So I tried some other themes, each of which gave the blog a completely different appearance. Of the about 20 different themes I tried, only three appeared to work reasonably well. About a third did not work at all, just giving an error message when trying to access the blog. The rest that didn’t work had formating problems, the most common being the columns appeared one above the other rather than side by side. These are all Wordpress approved themes from the Wordpress site. One that didn’t work was one of the Wordpress default themes. The other default theme was one of the only three that did work, but its text was ugly and the letters ran into each other on my browser, making the blog almost unreadable. The theme I’ve had to settle on seems to be working, though it is much slower in loading.
My question is: Why did Wordpress even change the software in the first place? Version 2.5.1 was easy to use and worked well. This version I’m using now, 2.7.1, hasn’t worked too well at all. The administrative panel, what I use to maintain the blog, is ugly, much harder to read and much harder to use. Before, I could just type in the text to add a new blog entry. Now I have to create an HTML file for each blog entry, which takes a bit longer and is one reason the blog hasn’t been updated as much as in the past.
This is a common problem with virtually ALL software. Developers change it for what seems to be no apparent reason.
I can understand this for commercial software. They are trying to compete with similar software so they are trying to at least give the illusion that they have made vast improvements to attract customers and upgrades. I find that frequently they only add features and seldom address defects or shortcomings in the present versions. Since I find that for most software I use probably less than 10% of its features and don’t even have time to learn about the rest of the features, I’m more concerned that what I do use works reliably and is easy and quick to use. And frequently these new versions just introduce a bunch of new problems.
Microsoft Vista is probably the best known example of an “upgrade” that is much worse in most people’s view than what it replaced. Vista came into being simply to try to force hundreds of millions of Windows users to upgrade so Microsoft could make more money. It is moves like this that are driving a lot of Windows users to move to Apples or open source software.
But Wordpress is free open source software. Why go through all this effort for no apparent improvement and cause all sorts of inconvenience to the software users?
I do not live software. I am a musician. I have better things to do with my life than to keep upgrading and maintaining software. Any time spent upgrading and maintaining software is time not spent writing and recording songs, practicing my instruments, trying to promote our music, writing this blog, etc. Any time spent upgrading and maintaining software cost me money, even if the software or the upgrade are free.
Upgrading one piece of software also frequently causes other things to no longer work. I am still using an old version of my main recording software Cakewalk Sonar (version 5.2) because:
1) None of the past upgrades have addressed any of the things in Sonar that have been causing me problems. I’ve even shown the Cakewalk reps in person at trade shows or road shows the problems I keep running into and it just seems to go over their heads or is forgotten. It seems to me these people don’t use their own software.
2) Most of the time I do a major software upgrade, a lot of the plug-ins no longer work. I spend weeks, even months, trying to get the plug-ins and other software (and some hardware) to work again. I can’t afford all the downtime due to trying to get these upgrades working again.
3) Frequently, a $150 upgrade with one piece of software forces me to spent over $1000 upgrading my other software to get it all working again. I don’t have that kind of money that I can afford to spend that much on software each year. This is one big reason why I am going more and more to open source software.
4) Other than the few deficiencies in the existing software, which often aren’t even addressed in the upgrades, the present software more than meets my needs. Why upgrade, risk the downtime and extra expense for no reason whatsoever? I’d rather be making music.
I am not exactly a technological neophyte. I have an electrical engineering degree, 23 years of full time design experience, have designed computers and integrated circuits, have a number of patents, and have written commercial software. If I’m having these kind of problems, what about your typical user?
If most software developers had to live by the same rules that people who make hard, tangible objects do, most software companies would have been out of business long ago.
By Cindy of Stone Marmot
I usually do two approximately 60 mile bicycle rides a week. Towards the end of each ride, I like to stop for lunch somewhere, since, after riding 60 miles, I’m really not in the mood to cook something (Actually, I’m seldom in the mood to cook).
A major consideration in choosing a place to eat is whether it has a safe place for me to lock my bicycle. You may be surprised how difficult places like this are to find.
As a minimum, I want a place where there is a solid pole or similar structure that I can run my bicycle cable or chain around and still go through both wheels and the frame of my bicycle. Running the cable through both wheels and the frame of the bicycle is the minimum necessary to secure it. After all, how many times have you seen a bare frame or just a bike wheel locked to a post? With a typical wheel with tire on a good bike costing at least $200, there is much incentive for thieves to take just the wheels.
The trend in today’s architecture is to have very thick (like 18 to 42 inches across) support pillars or no pillars at all for the overhangs outside these restaurants or strip malls. The thick pillars are often too big for a bicycle cable or chain to wrap around and still go through both wheels and the frame of a typical bicycle. Even the light poles in parking lots are often thick concrete now instead of metal or have very tall concrete bases.
The pole should also be such that the potential thief can’t just lift the bicycle and chain over top the pole or break the pole.
The place for locking the bike should also not be such that the bike can be easily hit by a motored vehicle. Spaces in parking lots are usually not too good as drivers can easily back their SUVs or trucks into the bikes, causing hundreds of dollars in damage to the bicycle and little or no damage to the motored vehicle. The motorist may not have even realized he hit something.
The bicycle should also be easily visible from the windows of the restaurant. It is not necessary to sit in the restaurant so that you can always see your bike, but things are less likely to happen to the bike if others in the restaurant can see the bike, especially since anyone near the bike would not know if one of those by the restaurant windows is the bike owner.
Those things many people think of when someone mentions “bicycle rack,” that is, those contraptions made of usually metal bars that you are expected to stick a bike wheel into, are not bike racks. They are actually potentially very damaging to most bike wheels. Bike wheels aren’t designed to withstand a lot of pressure from the side. If I find myself forced to use one of those things, I never stick any of my bike wheels into the bars of those racks. I always try to set my bike just outside one end of the rack and lock to the rack there.
Ideally, there is also some cover over the bike to protect it from rain. Here in Florida, most of the year this isn’t a big concern. But from the end of June to the beginning of October, our rainy season, it is not unusual for the day to start out perfectly clear, suddenly cloud up, rain extremely hard to 10 to 15 minutes, and then be clear again. I have often ducked into a restaurant that had a safe covered place for me to lock up my bike and had an early meal while waiting out the rain.
A relatively new problem I’ve been encountering a lot recently is that all the good places to potentially lock up my bike are already taken – by restaurant employees!! More workers are riding bicycles to their jobs, which is good! But I would think the restaurant could provide a safe place in back for employees to put their bikes and leave the choice spots in front for customers. Many restaurants have a fenced in area in back where they keep their dumpsters and other stuff. This seems like a better place for employees to lock their bikes. I have been forced to find another place to eat at least three times in the past three weeks because of this problem.
Over the years I, and other bicyclists, have noted the places that have safe places for us to lock up our bikes. These are the places that get our business. These are the places we tell other bicyclists about and take them to. And more people are riding bicycle these days out of necessity or environmental concerns. With the economy as slow as it presently is, the last thing a business wants to do is drive away potential customers. So, business owners, think about how you could easily accommodate us.
By Sid of Stone Marmot
A lot of guitar and bass amplifiers, particularly tube amps, have master volume controls. This allows you to set up the volumes of your preamps for the desired preamp overdrive or for the desired gain ratio between the preamps when using channel switching and just adjust the master volume for the desired volume for where ever you are playing.
Many players don’t like the master volume control because they claim it reduces the power amp overdrive, this overdrive resulting in a sound that many like, and takes something away from the sound even when you think you are not overdriving the output stage. These claims are valid though, with a properly designed master volume control, the control should be completely out of the circuit when the master volume is turned all the way up. With the properly designed master volume, you have the best of both worlds.
A lot of people, including myself, are using various techniques to reduce the power supply voltages in their tube amplifiers. Kevin O’Connor is one of the best known advocates of this with his “Power Scaling” circuits, which are well thought out and designed and recommended by many. But there are many different techniques used by many people for accomplishing this same end. Reducing the power supply voltages reduces the output power of your amp, allowing you to get that desired power amp overdrive sound at more reasonable power levels.
The question is: What power supply voltages do you reduce?
The most obvious answer (and probably cheapest and easiest to implement) is to reduce all the power supply voltages proportionately. But my experience is that this does not usually give the best sound, though this is subjective and you may feel otherwise. The reason is that an electric guitar has a very wide dynamic range. Though the average level out of a typical guitar pickup may be 100 mV peak about a second after hitting a note or strumming a chord, the maximum level could easily be over 500 mV peak in the first 20 milliseconds after the chord or note is picked. This voltage out of a guitar does not change with amplifier power supply voltages but only with the way you play and how the controls on your guitar are set.
My observation is that when you reduce the power supply voltage to a vacuum tube, the gain does not change that much. But the dynamic range, that is, how big the output signal can get before saturating, does change dramatically with supply voltage.
For example, Table 1 shows how the gain and maximum output voltage change with power supply voltage for a 12AX7A. These numbers are taken from the RCA resistance-coupled amplifier tables. The resistances were chosen because they are typical of a black or silver face Fender preamp stage. Note that when the supply voltage is reduced from 300 to 180 Vdc, the gain drops less than 10 %, but the maximum output voltage drops over 56 %. Going from a 300 Vdc supply to 90 Vdc is even worse, as the gain drops less than 33 % but the maximum output voltage drops almost 90%.
| Supply voltage |
Plate resistor |
Grid load resistance |
Max output V |
Gain |
Max output change from 300 Vdc |
Gain change from 300 Vdc |
| 300 Vdc |
100 kohm |
220 kohms |
57 V |
52 |
- |
- |
| 180 Vdc |
100 kohm |
220 kohms |
25 V |
47 |
56.1 % |
9.6 % |
| 90 Vdc |
100 kohm |
220 kohms |
6 V |
35 |
89.5 % |
32.7 % |
What does this mean? Well, if you have a 500 mV peak signal from your guitar pickup, with a 300 Vdc supply it will be amplified by 52 V/V, giving a 26 V peak signal at the output of this stage. There is plenty of margin between this desired 26 V output and the 57 V max output of this stage with a 300 Vdc supply, so the stage doesn’t saturate. But with a 180 Vdc supply, the 500 mVpk signal is now amplified by 47, giving 23.5 Vpk. This is very close to clipping with the 25 Vpk max output at 180 Vdc. At a 90 Vdc supply, the 500 mV input signal is amplified by 35, giving 17.5 Vpk desired output. But at 90 Vdc supply the stage can only out a maximum of 6 Vpk, so this stage is now very far into saturation.
So if you are trying to get just power amp distortion at lower volume levels without altering any of the characteristics of the previous stages, you really need to decrease only the output stage power supply voltages and leave all the other stages alone. Decreasing the power supplies for any other stage will probably result in that stage saturating sooner than desired and probably before the power amp starts to saturate.
But if you don’t reduce the supply voltages for any other stage, these stages will still be outputting the same maximum signal levels for a given input signal level. Reducing the power supply voltages for the power amp will result in the power amp starting to saturate with lower input signal levels to the power amp. So, to keep your amp sounding close to what it does when you turn it up most of the way, but only at a lower volume level by reducing the power amp supply voltages, you also need to reduce the signal input to the power amplifier.
A master volume control located between the phase inverter/splitter and the power amp provides the capability to reduce the input to the power amp as the power amp supply voltages are reduced. You have to manually adjust this master volume by ear to get the sound to be close to what it is with amp turn most of the way up.
Note that running with reduced power amp supply voltages will never sound exactly the same as running the amp at close to full volume for a number of reasons:
1) You aren’t driving the speakers or output transformer as hard at reduced supply voltages, so you are missing any distortions they may introduce.
2) You aren’t taxing the power supply as much, so you will not get the sag and other peculiarities that occur at higher current levels.
3) Your ears hear things differently at lower volume levels, particularly in the bass and high frequency regions.
By Sid of Stone Marmot
The Echo Mona is a digital recording studio computer input/output board. It had four A/D converter inputs, each with a preamp, and six D/A converter outputs, all with maximum 24 bit resolution and up to 96 kHz sampling rate. It is a fairly decent unit that had gotten good reviews when it first came out. I’ve been happy with mine except for one thing: The preamp gain controls are unreliable.
The gain controls started getting hard to set about a year after buying the unit. A small change in a gain control would give little gain change and then suddenly result in a big change in gain. The gain would also jump when you removed your hand from the control. Over the years these controls have gotten so bad that it is virtually impossible to set any reasonable gain levels. The problem is really apparent when I am recording a stereo input and I’m trying to match the channel levels for this stereo input.
Usually this is an indication that the control is dirty. Ordinarily you could squirt some contact cleaner into the control, turn it from end to end rapidly a dozen or so times, and the problem would be fixed. But these controls are the small plastic type with no obvious opening to squirt contact cleaner into.
Figure 1 shows the top of the Echo Mona circuit board. To get at this board, I had to remove virtually every mechanical fastener in the unit. Not very service friendly! The controls of concern are the small black and silver rectangular objects with shafts sticking out of them just to the right of the big black connectors. The fifth control at the far right of the board is the headphone level control. I’ve never had any problems with this control. All of these controls are mounted in the unit strictly by soldering the leads to the printed circuit board. This is not a very secure mounting technique. Fortunately, I haven’t had any problems yet with broken leads or solder joints.
Figure 1 - Echo Mona circuit board top
Figure 2 is a close-up of the gain control for channel 4. There is no obvious way to squirt electronic contact cleaner into the control. I tried squirting cleaner onto the control outside, hoping enough cleaner would seep through any material interfaces to get inside the control. But this did not seem to work.
Figure 2 - Echo Mona preamp gain control
The control is a 1.5 kohm reverse taper control. Two of the leads are tied together so that the control is acting as a variable resistor, not a potentiometer. The taper has a rather extreme variation, as the control changes from 1500 ohms to 200 ohms in less than a quarter turn, to about 50 ohms at half turned, and changing the remaining 50 ohms over the remaining half of the control shaft rotation. When adjusting, I saw the control jump 5 to 10 ohms for small rotations of the shaft. The resistance would also jump 5 to 10 ohms when I removed my fingers from the shaft. These kind of changes are significant when operating in the upper half of the control range.
I never use the controls in the first quarter of a turn area. Since I usually feed synthesizers, which all have their own output volume controls, into channels 3 and 4, I really don’t need the gains of these channels to be variable. This would also be true if you normally feed external preamps into these channels and just want a reliable line input. So I could replace the channel 3 and 4 preamp gain controls each with a fixed value resistor. So that is what I effectively did: I installed a 61.9 ohm resistor across the terminals of each control for channels 3 and 4. If these controls are turned full counterclockwise (minimum gain), the result is the the control’s full 1.5 kohm resistance is in parallel with the 61.9 ohm resistor for about 59.4 ohms equivalent resistance. This is about the same as if the control where normally turned up about half way. Even if the control were measuring about 1300 ohms, 1300 ohms in parallel with 61.9 ohms is about 59.0 ohms, less than a 0.4 ohm, or less than 1 %, change. This is acceptable.
The gain can still be adjusted a little. The minimum gain for these channels is now what used to be the midpoint gain before the resistors were added. 5 to 10 ohm jumps in the control now have a less significant impact on the channel gain for most of its range. Only at the extremely high gains, which I rarely use, do the control gain jumps become a problem again.
Figure 3 shows the underside of the Echo Mona circuit board with these resistors soldered across the terminals of the preamp gain controls. Figure 4 shows a close-up of one of the resistors. The top row of three pins on the control are for mounting. The bottom row of pins are the active resistance, with the two leftmost pins being tied together. So you can solder the resistor from the rightmost pin to either of the other two pins.
Figure 3 - Echo Mona circuit board bottom
Figure 4 - Echo Mona with resistor installed across gain control
To modify your unit, adjust the control to about where you usually set it. Then measure the control’s resistance. Choose a good quality resistor (preferably metal film) of approximately this measured value and solder across the control’s terminals as shown in Figure 4. The resistor must be small as it needs to fit between the bottom of the circuit board and the chassis with some clearance when the unit is reassembled. Be sure to clean off all the residual solder flux so you don’t have future noise or corrosion problems. Also, make sure there are no accidental solder bridges to or between the pins in the top row.
For the other two channels, I paralleled a 301 ohm resistor across each control. This gives about 244 ohms when the control is set for minimum gain, which is about the same as if the control were turned up about a quarter of the way before installing the resistor. Since this resistor has a much larger value than the ones installed in channels 3 and 4, channels 1 and 2 will be more sensitive to control variations than channels 3 and 4. But this is still much better than without the resistors, especially since I usually set these controls between 30 to 60 % of the way up before adding the resistors, so they were less sensitive to 5 to 10 ohm shifts in the control anyway.
This is not a complete fix. But it is a vast improvement and makes the Echo Mona very usable again. If you have decent soldering skills and the choice is either to do this fix or spend $500 to $1000 for a new computer audio interface, you may want to try this. It could save you a lot of money.
By Sid of Stone Marmot
Most guitarists feel that the best sounding distortion comes from a tube amp turned up almost full volume. Unfortunately, this is often not practical because it can be painfully loud, may disturb others, and be too loud for the place you are playing at.
One solution is to put a passive load between the amplifier and the speaker to absorb some of this excessive volume. There are many ways to do this. Probably the easiest, cheapest, and still pretty effective way to do this is with power resistors between the amplifier and the speaker. I understand this is the technique used by the old Scholz Power Soak, THD Hot Plate, Dr. Z Air Brake, and many other commercially available units.
Again, there are many ways to do this passive resistor load. A lot of these techniques, including the ones used by many commercially available load boxes, don’t maintain a constant impedance load to your amp as you change the attenuation. People debate whether this is important. You can search the net for these discussions. I decided I wanted to keep a constant impedance load to my amps.
The L-pad is one attenuator technique that maintains a constant impedance load to the source, a guitar amp in my case. But it still provides a variable impedance to the load, the speaker in this case. Again, many debate whether this is important.
The bridged T attenuator technique does present a fairly constant impedance to both the source and the load. Figure 1 is a schematic of a bridged T attenuator. Varying R1 and R2 changes the attenuation. If your source and load impedances are the same, then R3=R4=load or source impedance. The values shown are for an 8 ohms source and load impedances and a 3 db attenuation.
Figure 1 - Typical bridged T attenuator
http://amps.zugster.net/articles/attenuation has more information on the bridged T and L-pad attenuators. It also has a table for the component values for different attenuation levels. Table 1 below shows the values I would ideally need for the attenuation levels I wanted for a box for 8 ohm amplifier and speaker impedances.
Table 1 - Ideal resistor values for passive attenuator
| Attenuation (db) |
R1 (ohms) |
R2 (ohms) |
| 0 |
open |
0 (short) |
| - 3 |
19.39 |
3.30 |
| -6 |
8.04 |
7.96 |
| -9 |
4.40 |
14.55 |
| -12 |
2.68 |
23.85 |
Figure 2 is the schematic of my resulting attenuator box. I tend to build my stuff out of parts I salvage from other stuff people are throwing away, such as old TV sets, organs, computer CRTs and power supplies, etc. It is called "recycling" by some. I dug through my parts boxes and put power resistors in series and parallel combinations until I got the approximate values and combined power levels I desired. I don’t show all these different resistors but only the resulting values of the combinations. Since buried with all these resistors were already an 8 ohm and 4 ohm passive load, I added two more switch positions for 8 ohm and 4 ohm passive loads, which are useful for testing amplifiers without speakers attached.
Figure 2 - Schematic of my attenuator box
I achieved my desired resistor values by putting resistors from the various switch positions in series. For example, to get - 6 db attenuation, I would switch to switch position 3. At this switch position, R1 in Table 1 is approximated by R1d and R1c in the schematic in series and R2 in Table 1 is approximated by R2a and R2b in the schematic in series. Table 2 shows what the ideal values for these resistors in the schematic should be and what I was able to achieve with my series/parallel combinations.
Table 2 - Resistor values for my passive attenuator
| Resistor |
Ideal value (ohms) |
Min power (W) |
Actual value (ohms) |
Actual power (W) |
| R3 |
8 |
100 |
8 |
200 |
| R4 |
8 |
25 |
7.96 |
25 |
| R1a |
2.68 |
18.8 |
2.70 |
30 |
| R1b |
1.72 |
9.0 |
1.71 |
17.3 |
| R1c |
3.64 |
11.4 |
3.60 |
20 |
| R1d |
11.35 |
12.1 |
11.30 |
17.1 |
| R2a |
3.30 |
20.7 |
3.29 |
47 |
| R2b |
4.66 |
29.3 |
4.69 |
58 |
| R2c |
6.59 |
10.4 |
6.54 |
17.4 |
| R2d |
9.30 |
7.4 |
9.29 |
10.7 |
Note these are calculated values, not measured. I don’t have equipment that can measure resistances that accurately. I don’t think it matters, either. Plus or minus 10 % is probably good enough.
Also, the minimum power shown in Table 2 is for a 100 W minimum power rating at all settings. I calculate that, with the components I used, I achieved a minimum of 140 W for all the attenuation settings and 200 W for the passive 4 and 8 ohm load settings. If you want a different power rating for your load box, just adjust these minimum powers proportionately. For example, for a 200 W attenuator box, double all the minimum powers in column 3 of Table 2. Just to be safe, I would avoid using this box or any other attenuator box on any amplifier that is anything close to the rated power level of the box.
In theory, R4 doesn’t have any current flowing through it under steady state conditions. One might think you could just delete this part or use a very low power resistor for R4. In fact, I understand that the Dr. Z Airbrake, designed by Ken Fischer of Trainwreck fame, does omit this part. But I suspect it does have an effect during transients, so I left it in, especially since I had the parts lying around and it cost me only some time to include it.
Table 3 shows the attenuation for each of the switch settings. I used a pushbutton switch assembly I salvaged from the rhythm section of an old organ (I removed the "Foxtrot" "Waltz," etc., labels off the pushbuttons.) You will probably have a next to impossible time trying to find an equivalent switch assembly. An alternative is to use a double pole, six position rotary switch. Just don’t wire up switch position "7." If you still want to be able to switch to a 4 ohm passive load, replace S1c in the schematic with a SPST toggle switch. This toggle switch would be left open for all settings of S1 except position 6, where open on the toggle switch would select the 8 ohm passive load and closed would select the 4 ohm load. But be sure to return the toggle switch to open before using any other settings on S1.
Table 3 - S1 Switch positions
| S1 Switch position |
Attenuation (db) |
| 1 |
0 |
| 2 |
- 3 |
| 3 |
- 6 |
| 4 |
- 9 |
| 5 |
- 12 |
| 6 |
8 ohm passive load |
| 7 |
4 ohm passive load |
Be sure that whatever switches you end up using have adequate current capability. For example, a 100 W, 8 ohm impedance load box can have over 5 amps peaks running through the switches, a 200 W, 8 ohm box twice that (10 amps), a 200W, 4 ohm box 3 times that (15 amps), etc.
Figure 3 shows a top-front view of my attenuator box. The case is from a old AM-FM tuner I got for $1 at a garage sale. The organ pushbutton switches are the only controls. I obviously forgot about the one switch assembly mounting screw which intrudes on my labeling.
Figure 3 - My amplifier output attentuator box
Figure 4 shows the inside of my box. It is definitely not an artistic masterpiece, but it works and cost next to nothing. You could use series/parallel combinations of whatever resistors you have or can find to get the values in Table 2 like I did. Or you can do something like Dr. Z did with the Air Brake and replace R1 and R2 each with a big multitapped power resistor and adjust the taps to get the values you want. The Ohmite 210 series parts, either 100 W or 225 W, are good examples of these tapped resistors, which Mouser Electronics carries. These would be much easier and neater to use, though probably more expensive than individual resistors. Just remember that each tap can only handle a fraction of the total resistor rated power. For example, a 5 ohm tap on a 25 ohm, 100 W resistor can only handle:
(5 ohms/25 ohms) x 100 W = 20 W.
Figure 4 - Inside my amplifier output attentuator box
To use as a passive load, you still plug the input of this box into the speaker output of the amplifier. Just don’t plug a speaker into the output of the attenuator box.
Does this load box sound just like an amp running at full volume, only quieter? Not quite. This is partly because the speaker is not being driven as hard, so we are missing any distortion due to the speaker. But mostly because we don’t hear the same at lower volumes as at higher volumes, thanks to the famous Fletcher-Munson curves and probably other physiological and psychological effects. But I can get good sounds out of my amps at reasonable volume levels with this box, which is all that is important.
Note that using a device like this can be hard on your amplifiers. The problem is not that the attenuator box does anything harmful to your amps. The problem is that running your amplifiers turn up to their maximum volume levels is hard on the amps and their tubes, whether or not you use a box like this to attenuate their actual volume levels. So use with care.
A hint: The 4 and 8 ohm passive load positions can be useful for other stuff beside dummy loads when testing amplifiers. For example, you could use the passive load to replace one of the speakers in a twin speaker cabinet. Or, if you usually use two speaker cabinets, you could replace one of them with this box switched to the appropriate passive load position. In both of these situations, there would be a noticable drop in volume and the sound would probably be less focused and more dispersed.
By Sammy of Stone Marmot
A lot of homeowners are whining about the fact that their houses have recently dropped in value. The most vocal are those who are complaining that their mortgages are more than the value of their houses. So what? Isn’t that true for most anything you take a loan out for? Why should houses be any different?
For example, most people borrow money to buy a car. The instant they drive the car off the car dealer’s lot, the vehicle has lost at least 20% of its value. Few complain about having to pay off a car loan because the loan is for more than the vehicle is worth.
Some people take out loans for a big wedding. Or, more likely, they charge it to a credit card and take months, if not years, to pay it off, which is effectively the same as a loan. Once the wedding is over, there is nothing of monetary value left to show for their debt. But most people still pay off the loan or credit card.
The same is true for most anything else people buy with loans or credit cards, such as furniture, big screen TVs, boats, whatever. Few whine that their debts are for more than these items are worth. Most pay off these debts.
But many of these people will reply that homes are different. And they are right:
1) You can get by and live a reasonably comfortable life without a boat or big wedding or fancy furniture. You can even reasonably make it without a personal motor vehicle. But you must live somewhere. Being homeless is not a terribly comfortable lifestyle. So just be thankful you have a home.
2) A house will last a very long time if reasonably maintained. All five houses I can remember living in were built before 1960. My present house, which I find rather comfortable and am happy with, was built in 1959 and is 50 years old this year. How many people can say that about their marriages, boats, TVs, furniture, and especially, vehicles? Yet few have a problem paying off debts for these relatively short-lived items, but are upset about paying off a very long life item such as a house because it is temporarily worth less than its loan.
3) Over the long term, most decently maintained houses appreciate in value, usually significantly. There are exceptions, such as houses that suffer some disaster or are in a bad location. There can also be temporary downturns in the housing market, like we had in the late 1980’s-early 1990’s. But over the long term, most houses appreciate in value.
So people who intelligently selected and bought a house they expected to live in for a long time should have no problem paying off their mortgages, even if the house has dropped in value so that it is now worth less than the mortgage. They have something worth the money and that should give them a life of happiness. The real reasons people are complaining are:
1) Many people did a poor job of selecting their houses and bought more than they could over the long term afford.
2) Many were speculating and not buying houses primarily to live in, but as short term investments. This is definitely the wrong reason to buy your primary residence.
3) Many are jealous of government efforts to bail out those who are in danger of defaulting on their mortgages and they just want some of these government handouts. This is another example of how government interference in the marketplace often causes more problems that it solves. After all, this whole mess was caused by the government manipulating interest rates 6 or 7 years ago to artificially low levels to try to avoid a long recession. Instead, these low interest rates encouraged people to buy houses they couldn’t in the long run afford and to consider houses as speculative short term investments.
The real problem we now have is that all these shortsighted and selfish people have put a big drag on the entire economy so that now people who had typically planned and chosen well are losing their jobs and are suffering. Our efforts should be concentrated on helping those who are losing or have lost their jobs, not on helping those who overextended themselves. There is no way out of the present economic situation without someone being hurt. Therefore, the pain should be borne by those who caused the situation, not the innocent bystanders.
By Sammy of Stone Marmot
This may be dating me, but I remember a time, maybe in the 1960’s and 1970’s, where companies bragged about their “easy open” packages. It was very prominent in a lot of their advertising. Many companies considered this a big selling point.
Now, most packages are a nightmare to open. You frequently need some sort of tool to open most every type of package.
For example, dry breakfast cereal used to come in a waxed paper bag in a cardboard box. The cardboard box is pretty much the same and just as easy to open. But before, you could easily neatly tear the waxed paper bags open with your bare hands. Now they come in a plastic bag that is next to impossible to tear open at all, let alone to tear it without the bag suddenly shredding and spraying cereal all over the place, after which the bag is virtually impossible to reseal.
Most every individually vacuum packed item, such as frozen fish fillets, comes in a plastic bag that absolutely cannot be torn open. You must use some sort of tool to open these packages.
So now you must keep scissors in the kitchen to open these packages. These scissors should not be the same ones you use for other things, such as cutting tape or opening mail, to avoid contaminating your food. You must wash these scissors after each use to get the food grease or whatever off the scissors. This is a lot of unnecessary extra effort which we didn’t have to do in the past. Why? Most all this stuff already comes in some other outer protective package, like a cardboard box or plastic bag, to protect the inner packages from normal handling.
Some plastic bags have little notches on one or both sides, supposably to make it easier to tear the packages open. My experience is that most of these notches do help to get the tearing started. But a lot of these bags either tear towards the nearest edge, leaving the bag unopened, or down towards the middle, splitting the bag wide open and spilling the contents. The bags that have those resealable plastic “zippers” are most notorious for tearing to the nearest edge, leaving the bag unopened.
Plastic bubble packs are the absolute worst items to open. The soft plastic ones with a cardboard back usually cannot be torn open without obliterating the cardboard (or breaking the product), which often has the instructions and other needed information printed on it. Even with tools you have difficulty preserving the information printed on these cardboard backs.
The hard plastic ones are frequently next to impossible to open even with tools. Scissors often can’t cut the convoluted edges of these hard plastic packages, and the scissors often break trying to cut these packages. I’ve often had to resort to using my bandsaw to cut these packages open. What do people do who don’t have bandsaws? I think it is a fairly safe assumption that most households and offices don’t have bandsaws. Many people, including myself, have been hurt trying to open these packages. Aren’t these manufacturers concerned about liability?
Why are these manufacturers putting their customers through such hell to use their products? Are they hoping we damage the product in the effort to extract it from its package (which has happened more than once) and we have to buy another? That doesn’t work for me. If I damage a product trying to extract it from its package, that company has lost me forever as a customer.
These obviously are not the best of economic times. The last thing you want to do is give people another excuse for not buying your products.
By Sid of Stone Marmot
The old 1980’s Electrovoice (EV) speaker cabinets with angle aluminum on all the edges were great cabinets. Examples are the B115-M, B215-M, S12-2, S15-3, S18-3, LF215, FM12-2, and FM12-3. They were very solidly constructed, had great speakers in them, and sounded very good, particularly with bass guitar and electric guitar. But, over time, the metal grills protecting the speakers on all these cabinets would start to rattle, particularly when playing lower frequencies through the cabinets.
Examining my EV B115-M cabinet showed that the grill is supported at the top and bottom by being clamped between the aluminum edge protector and the wood of the cabinet. The underside, that is, the side that is against the metal grill, of the aluminum edge protector has a strip of foam that separates it from the grill. Figure 1 shows a picture of the top edge of the cabinet with the aluminum edge protector removed and laying on top of the cabinet. The sides aren’t supported but are instead stiffened by bending the metal grill at a 90 degree angle in towards the cabinet.
Figure 1 - EV speaker cabinet edge with edge protector removed
This should be sufficient to provide a strong, secure, and rattle free attachment for the metal grill, and it does when the cabinets are brand new. But, over time, the foam between the aluminum edge protector and the grill disintegrates and the grill becomes loose. You also now have a metal to metal contact between the grill and the edge protector. This is what causes the rattle.
This can be easily fixed by replacing the now disintegrated foam with foam weatherstripping that is readily available in almost any place that sells home improvement supplies. I myself used 3/16 inch thick “Camper Seal Foam Tape,” simply because I had a lot of it already left over from previous projects. This stuff comes 1.5 inches wide which I had to cut in half (3/4 inches wide) to fit under the aluminum corner protector without sticking out beyond the edge. This foam weatherstripping has an adhesive on one side, as do most of these tapes, which makes application easier.
Many of these cabinets also have a rectangular cutout in them for a high frequency attenuation control. Figure 2 shows a picture of the one on my B115-M. You also need to remove the screws that secure the frame around this cutout and put some more foam under this frame and reinstall the frame. You can barely see some of this gray foam between the top edge of this frame and the grill in Figure 2.
Figure 2 - Cutout for high frequency control
These fixes solved the rattle in my grill. They should also solve the rattle in yours, unless your grill is severely bent. If it is bent, you need to straighten it out first, making sure the grill isn’t touching any speakers.
By Sid of Stone Marmot
Warning: To keep this article a reasonable size, I purposely skipped listing all the safety steps I had taken while troubleshooting this amp. There are some very high and potentially lethal voltages and currents in these tube amps. If you are not intimately familiar with the safety precautions necessary to troubleshoot tube amps, don’t even think of trying this yourself. Take the amp to a qualified electronics technician. The amp isn’t worth your life!!
Someone recently gave me a Giulietti vacuum tube amplifier. It is 18.5 x 14 x 10 inches and weighs less than 22 pounds. It has a 12 inch alnico Jensen P12S speaker in it, date coded spring of 1960. It has five tubes: two 6SL7s, two 6V6s, and one 5Y3. It has three controls: Volume, Tone, and Tremolo, all scaled from 0 to 10. Figures 1 and 2 show the front and back of this amplifier.
Figure 1 - Giulietti tube amplifier front
Figure 2 - Giulietti tube amplifier back
I never heard of Giulietti. But the 6SL7s, which are octal tubes like the 6V6s, sounded familiar, like something Ampeg might use in one of their older amps. So I looked through my various schematics and found a number of Ampeg amps that did use this tube.
I then popped the back off this amp. A schematic is glued to the back cover. The schematic looks like an exact print of the Ampeg J-12B Jet schematic, except, as shown in Figure 3, the lower corners were neatly cut out. (A bigger schematic is here.) The lower left hand corner would ordinarily be where the Ampeg model number would be, whereas the lower right is where the Ampeg logo would reside.
Figure 3 - Giulietti tube amplifier schematic
So, I did a little research. It turns out that from about 1958 to 1961 Ampeg built amps for two accordion manufacturers, Giulietti and Noble, which they then rebranded and sold as their own amplifiers. Consequently, this Giulietti amp I have is really a 1960 Ampeg Jet.
Since the amp is almost 50 years old and I was told it hadn’t been turned on in at least 15 years, I just the assumed the power supply filter caps would be bad, the number one problem with amps this old, and replaced them before turning it on. Now many people would just try it as is without replacing these caps. If the caps are then bad, they could literally blow up and/or take out some other parts with them at power up. But even it the amp does appear to work, the caps are probably rather leaky and are pulling down your supply voltages.
I recently had this experience with a 1971 Ampeg V4 I acquired. I powered it up as is, after replacing a few visibly bad parts. It worked. But all the power supply voltages where lower than expected, with the highest being about 520 Vdc instead of the about 545 Vdc expected. The amp was measured at 110 Wrms max, more than the 100 Wrms advertised rating but less than the about 130 Wrms max these amps usually put out. I replaced the filter caps and the supply voltages all rose to what was expected, with the max power now measuring the 130 Wrms expected. These leaky power filtering caps could also have an impact on the amp’s tone, though that is much more subjective.
Figure 4 shows the back of the amp opened up with the power supply filter caps replaced , though I left the original can in, unconnected. After replacing these caps, I powered up the amp and it sort of worked. The tremolo wasn’t working and it distorted with any volume at all and was very raunchy when turned up to two. This didn’t seem right so I further investigated the amp.
Figure 4 - Giulietti tube amplifier back open with filter caps replaced
I suspected leaky coupling caps. This is a very common problem in old tube amps and is easy to test for. The input grid of every non-rectifier tube should be tied via a resistor to a DC voltage (usually ground, or a minus voltage for fixed bias power tubes). There should be no DC voltage drop across these grid resistors (a few tenths of a voltage is usually acceptable, though not ideal). This power amp is cathode self biased, with the cathodes of the 6V6s tied together and then going to ground through a 250 Ohms, 10 W resistor. This means the input grids of these tubes should be tied to ground through some resistors, which they are. But I initially was measuring around 55 Vdc at the grids of these tubes instead of the 0 Vdc expected. All the other input grids had the expected DC voltages on them.
So at least one of the capacitors feeding the input to these 6V6 power tubes was leaky. Since the tremolo modulation is injected here, there is an extra 1 Megohm resistor here between the connection of the 270 kohm resistors coming from each 6V6 input grid and ground, with the tremolo modulation being applied across the 1 Megohm. That means that three caps are feeding this circuit, a 20 nF from each side of the phase inverter circuit and a 100 nF from the tremolo circuit. Any one or more of these caps could be leaky.
An easy way to test which one is to lift one side of each cap one at a time and see if the problem goes away. This does render the audio portion of the circuit inoperable, but the DC biases should still work properly. It turned out that all three of these caps were leaky.
But replacing all three caps didn’t totally fix the problem. I was still measuring about 5 Vdc at the grids. The tubes could be leaky, but I swapped them out with known good tubes and that did not solve the problem. So I measured the resistor values. The two 270 kohm resistors were measuring around 300 kohms, which is acceptable for this circuit. But the 1 Megohm was measuring about 7.5 Megohms, way too high! So I replaced this resistor. Now the power tube input grids were measuring around 0.3 Vdc, which is acceptable.
But the tremolo still wasn’t working. Frequently, the values of the three caps feeding the grid for this tube have drifted too far from nominal values for this phase shift oscillator to have the proper phase shift around the loop to work. But I noticed that the plate voltage was way off, about 40 Vdc. I measured the plate voltage of the other tubes and the one side of the phase inverter (pin 5) was also way off, about 55 Vdc. Table 1 shows the expected voltages listed on the schematic on the back of this amp. All the other plate voltages seemed reasonable.
Table 1 - Voltages listed on Giulietti schematic for various tube pins
| Tube |
Function |
l |
Pin |
Vdc |
l |
Pin |
Vdc |
l |
Pin |
Vdc |
| 6SL7 |
preamp |
l |
5 |
140 |
l |
6 |
1.8 |
l |
|
|
| 6SL7 |
tremolo |
l |
2 |
110 |
l |
3 |
1.2 |
l |
|
|
| 6SL7 |
phase inverter A |
l |
2 |
140 |
l |
3 |
1.6 |
l |
|
|
| 6SL7 |
phase inverter B |
l |
5 |
135 |
l |
6 |
1.4 |
l |
|
|
| 6V6 |
power amp |
l |
3 |
310 |
l |
4 |
300 |
l |
8 |
18 |
So I measured the resistance of all the plate resistors. These plate resistors often drift with time and use to voltages far off their original, usually on the high side. The tremolo plate resistor was measuring about 1.6 Megohms instead of 270 kohms and the plate resistor of the phase inverter side in question was measuring about 700 kohms instead of 120 kohms. Both these reading were way too high. The plate resistor for the phase inverter side that appeared to be working was measuring about 320 kohms instead of 120 kohms, which is also high and should also ideally match the other side of the phase inverter. So I replaced the all three of these resistors.
Now the amp is 100% functional. It puts out about 12 Wrms. It still breaks up early at around 3 on the volume control. But it is mostly clean up to there and has a much smoother sounding distortion when it does break up.
The amp is rather bright. This is probably due to the Jensen P12S, which is a 13 W speaker with the smallest alnico magnet of any 12 inch Jensen made for musical instrument amps. I did try the amp with other speakers and you can get a lot more bottom out of the amp with the right speaker.
The plate resistor of the preamp stage was measuring about 164 kohms, a little high for this 120 kohm resistor. But this is probably acceptable. A lot of the “mojo,” the special sound of these old vintage amps, probably comes from parts that have drifted from their design specs. This can be good or bad and is one reason why a lot of supposably identical vintage amps don’t sound the same. A lot of the best sounding classics may be ones where the component values have by pure chance drifted into a sweet spot, whereas the ones that didn’t sound so sweet have already been scrapped or rebuilt. So the classic amps we are hearing are the good ones that survived with the bad ones already being weeded out. So I’ll try the amp for a while with this value, and a few others, off from ideal. If after some time I don’t like it, I can always change them then.
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