The Amp Garage

I'm not trying to be dissmissive here, but find what works for you. These threads seem to stir up controversy and division where there is none. Some people can hear a difference in the change in sound a certain capacitor/dielectric makes, some can't. It's not snake oil, just a capacitor. The audibl...

Oldish thread but I was just piddling with this thing today. I bought the transformer set from APD and I wondered about the impedance mismatch. I used a Fender type choke. My understanding is that it is the same OT as used in their 30W amps. Using it at 'regular' output impedance setting it is a st...

Throw it all on a microcontroller with a ULN2003A as the final driver. Then you can add MIDI switching support. Atmel ATmega328P could easily handle this, which you could easily code with a Arduino UNO R3.

Yeah, I'd stayed away from the classic 4053 and its brethren, due to sometimes large voltage signals in tube preamp stages. Hadn't looked at the TMUX4053 figuring it was similar. The max supply differential on the TI part is 24v (=/- 12v). The AD part is a bit wider at a max Vss-Vdd of 44v, but the...

CD4053 has been used in MIDI preamps, namely the Marshall JMP-1. Contains 3 SPDT CMOS switches. The updated version is the TMUX4053. Can run on up to a 28V supply, and signals can be within -0.5V of Vss and +0.5V of Vdd, so 29Vpk-pk (about 10Vrms, or +22dBu). Your device is rated for +/-15V, so 30Vp...

$50 per board + $25 setup fee per order + freight. Orders shipped within 48 hours. This is a new production "short" 1969 plexi eyelet board. Like the 12xxx series but not perforated. Same as the regular Plexi eyelet boards, but without the main rectifier and snubber cap section. These were used in S...

Yeah the FWB doubler would be a far better candidate for that sort of thing. That's what I was under the impression you were doing.

In circuit analysis a circuit part that delivers a current is called a current source. Other circuit parts connected to the output port of the source constitute the corresponding load. I was looking for a more specific answer based on a statement you made. The caps alone can't supply any DC current...

Helmholtz wrote: ↑Fri Aug 07, 2026 12:48 am It just occurred to me that taking the screen voltage from the point between the stacked reservoir caps won't work.
The caps alone can't supply any DC current.

Legit question...what do you think is the current source in an amplifier?

You could place the standby switch between the screen supply and the screen bus.

I was in a dead rush when I wrote that. But yes, run the MOSFET(s) in linear mode and keep them cool enough not to die. You can get MOSFETs with high enough voltage ratings to test tube power supply voltages, and the ability to dissipate significant amounts of heat per device. Unlike bipolars, MOSF...

Shelf life for electrolytic capacitors is 2-3 years. I have some that I installed in an amp I still haven't finished building since I started it in 2015. It's been through several moves, stored in a garage, then in my bedroom, etc. Finally getting around to finishing it up this year. I ordered a bra...

That is a 40% "Ultra Linear" tap. It combines characteristics of triode and pentode operation, giving the high power output of pentode mode with the linearity of triode mode. The closer the tap is to the plate, the more "triode-like" it performs. The closer to the B+ tap, the more "pentode-like" it ...

I, too, replaced my WES51 with a WE-1010NA. The tip it came with oxidized within the first few minutes of operation. Replaced the tip and it works beautifully. Keep it set at 650°F, which, for most solder joints, will more than suffice. From what I understand, they had a QC issue with a batch of the...

I so read this thread title wrong :wink: :D People refuse to accept that when you bring something in for repair, you're not so much paying for the repair itself as you are paying for my time. Sure, part of it buys the required parts and materials, but the labor pays for my time and experience. The r...