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Another Giulietti - Ampeg

By Sid of Stone Marmot

July 25, 2009

A couple readers of this blog have contacted me letting me know about the Giulietti amps they own. One, Nathan Neves, has sent numerous pictures of his amp and has given permission for me to share them with you. So attached are some pictures of his Giulietti.

His amp, shown in Figure 1, appears to be a relabeled version of an Ampeg Mercury M-12. It looks to be in almost new condition. It appears to have been manufactured and purchased in 1959. The Mercury first went into production around 1959 and this particular model was made by Ampeg until about 1965, though the Giulietti version was probably discontinued after 1961. This model uses 6V6 output tubes and was rated at 15 Wrms. Later versions of the Mercury used 7591 output tubes.

Figure 1 - Giulietti tube amplifier front

Figure 1 - Nathan's Giulietti tube amplifier front

Figure 2 shows the control panel. It has two separate channels, each with a volume and tone control. From the schematic it appears that Channel 1 is brighter sounding than Channel 2. The tremolo controls are between both channels and affect both channels the same.

Figure 2 - Giulietti tube amplifier controls

Figure 2 - Nathan's tube amplifier control panel

Figure 3 shows the back of the amp. Figure 4 shows the back open. Notice the 12 inch alnico Jensen P12R speaker. A lot of people would be interested in this amp just for this speaker alone. This speaker at that time was rated about 15 W, compared to 13 W for the P12S in my Giulietti. This P12R also has a bigger magnet, which should give it better bass response. Also notice that all the tubes are octals (6SL7s for the preamps, tremolo, and phase inverter, plus the 6V6 output tubes and 5Y3 rectifier). Also notice the "doorstop" footswitch for the tremolo.

Figure 3 - Giulietti tube amplifier back

Figure 3 - Nathan's Giulietti tube amplifier back

Figure 4 - Giulietti tube amplifier open back

Figure 4 - Nathan's Giulietti tube amplifier back open

Figure 5 shows the schematic on the inside of the back cover for the amp. A bigger version of the schematic may be found here (though it will probably take some time to load at 2.3 MB and be bigger than your screen; you'll need to scroll). The corners are cut out where the Ampeg logo and model numbers would usually be found, just like my amp. But just below the title "Voltage Measurements" over the voltage chart is the phrase "(Model M-15 slightly higher)." This M-15 probably refers to the Ampeg Mercury M-15, which was the same amp in a bigger cabinet with a 15 inch speaker. Note that later versions of the M-15 had 6 input jacks and used 6L6 output tubes and a 5U4 rectifier and put out a bit more power.

Figure 5 - Giulietti tube amplifier schematic

Figure 5 - Nathan's Giulietti tube amplifier schematic

Nathan also found this label inside the cabinet (Figure 6). He states that this was where the amp was purchased, with the date either being the date of purchase or the date the amp was received by the store. Whichever, it is a dead giveaway in dating this amp.

Figure 6 - Label in Nathan's Giulietti

Figure 6 - Label in Nathan's Giulietti

As you can see, this amp is in excellent cosmetic condition. If it is also 100% electrically functional, it probably sounds pretty sweet, also, judging from my past experience with amps with similar circuits. Nathan has a real prize on his hands. I'm jealous!

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