The Amp Garage

Disraeli Gears - Cream - 1967

A number of builders have expressed concern that this amplifier gets hot. I also noted my build seemed to give off a lot of heat while doing the initial voltage measurements. Some have accepted this and others plan to facilitate cooling by including a fan in the cabinet. I wanted to do some temperat...

I wanted to document the final stages of construction. To verify the bucking transformer operates properly, I plugged into the 115 VAC outlet and measured voltages in the amp using the GZ34S rectifier tube. These voltages are posted below and agree closely with Charlie’s original observations. The B...

Martin, yes the documentation above does not inspire much confidence. Hi Plexi - Seems that the 330-0-330 transformers work well for this amp. I considered grounding my HT CT through a zener to drop the high voltage. However, the solution I actually pursued was to build a simple bucking transformer ...

Martin – I will order a JJ 5Y3GT to substitute for the Sovtek tube to see if this drops B+ down to be more in line with the expected - thanks. Hi 68strat - thanks for your interest and comments. The observed IR drop across the 250R cathode resister was 23.9 volts indicating a 95.6 mA (total for both...

rogb - You mentioned earlier that you might try the higher voltage (355-0-355) secondary. Is the 399 VDC B+ you are now obtaining still using your 330-0-330 secondary? Also wondering what type of GZ34 (current production or NOS and brand) you are using. Thanks.

Scott

Thanks Drew, sounds like something reasonable to try. I don’t know much about rectifier tubes, much less NOS rectifier tubes. Are there any specific NOS 5Y3s you might suggest that could fit the bill without breaking the bank? If so, I will certainly try. Rogb – thanks for the kind comments. I have ...

Thanks for the kind words Mark. Yes, it would have definitely helped having elf hands to assemble the parts and solder this in the limited chassis space!

Several builders have posted voltages obtained with the Magnetic Components 40-18021/40-18022 transformer set. Some obtained B+ voltages that agreed with Charlie’s report; however, it seems the majority of builds gave higher B+ compared to the desired 398 VDC. Below is a voltage chart using my line ...

Here is the assembled amplifier. I considered using a TP40D power transformer from David Allen. This seemed to be a nice choice that allowed for a lot of options but I decided to stick with my original objective of building the Tweedle Dee, as presented by Charlie Wilson, and avoid getting sidetrack...

Hi Folks, I am currently getting near completing a Tweedle Dee amp build. I would like to thank Charlie Wilson and the other TAG members for taking the time to post photos and describe their builds and modifications. Although numerous impressive Tweedle Dee builds have been highlighted here in the p...

Joe Bonamassa’s new CD release, Different Shades of Blue – he really amazes me. Like the whole CD but especially like tracks 2 (Oh Beautiful!), 6 (Never Give All Your Heart), and 8 (the title track).

Someone different that can achieve impact in his compositions without excessive notes is Tino Izzo. “Dami la Forza” is an example, although there are some runs toward the end:

https://www.youtube.com/watch?v=EKtQJosb-1Y

His arrangement of O Holy Night would be another.

Scott

Phil - I bought a Trek Singletrack 950 mountain bike in the early 90’s and still ride it ~65 miles /week in the summer along paved paths that parallel the Columbia and Snake rivers. It is kind of heavy but it is built like a tank. I use with Crossroad tires inflated to ~72 psi (80 psi max) and it is...

RJ - Yes, this amp has certainly beat me into shape a bit - it is also clear I need to become a getter guitarist as it is very articulate. Jelle - thanks for the explanation. RCGPNY1- I recall seeing your build photos and if I remember correctly, there was only one difference in the components that ...