Tube Amp Archive

1) If using a bridge rectifier with the artificial centre tap, is it better to keep the Standby switch where the Traynor currently has it where it lifts the ground from that Bridge Rectifier? Or have it after the rectifier and first Filter caps? neither, lift both ac wires instead Is there a second...

Bad Cat was really good about sending me a new one. $90 USD plus shippings is pretty hard to beat.
To streamline production, it looks like they have the same PT for many (or all) of their amps with different taps for each model.
As I suspected, there is also a 15V tap for the reverb and relays, etc.

Using the tonestack calculator to see what's currently going on: If my controls are at noon, it's probably doing something like this: Hot Cat Standard Tonestack at noon.png So, the controls are usually dialed in more like this: HotCat Standard My Settings.png If I lower the slope resister and increa...

Probably the biggest thing that annoys me now about this amp is that anything above quite low on the treble control just sounds really bad... it's more like a fizz control as the gain gets higher... the ugliest form of fizz even though the "edge" control does some of that high end gain too (but I do...

Even though it is in a different thread: https://ampgarage.com/forum/viewtopic.php?f=6&t=38105&start=30 I should update this thread to show the current iteration of this amp: Hot Cat with Elevated Heaters and Dumbleator.png It now has an active FX loop (Martin's version of the Dumbleator) and elevat...

I've requested some gut shots and those should be coming to me tonight. I'm hoping that reveals some of what is going on in these things these days. Also, the seller said that he talked to bad cat and they are willing to sell replacement Power transformers... So I should have an idea soon on what th...

Ever since I built my own version of a Hot Cat out of an old Traynor, I've been lending it out to a friend as their band is recording a bunch right now. He has wanted to buy it, but I'm too attached to it to sell. I found a pretty new Hot Cat 45 combo closer by that apparently had a bad PT. The guy ...

Marshall powerbrake, attenuation varies as needed, sometimes I use NONE and just let it rip. Transformers.... Mojotone Mojo791 ATS5200 output. Amp Parts Direct APD-8065H power. Using 2 4x12s is impractical for my customers. I need practical recommendations for tonal response modifications in the ci...

I've continued to experiment trying to address this issue because I also like the eq/gain affect of having the bright switch on. Currently in my Liverpool and Express I have either no presence or a preset wired in amount and use that pot position for a cut control. In my Express, I keep upping the ...

Looking good! Thanks for sharing. I'm late to the party seeing this. Are you finished it now?

I've continued to experiment trying to address this issue because I also like the eq/gain affect of having the bright switch on. Currently in my Liverpool and Express I have either no presence or a preset wired in amount and use that pot position for a cut control. In my Express, I keep upping the c...

So the max cathode to heater voltage on a 12ax7 is 180V. Not always. Some are rated as low as 100V and some as high as 200V, and the positive and negative limits may be different. Oh, interesting. I guess I shouldn't assume. I should check what I have in that position. I popped a somewhat modern (l...

See limiting values p5 https://frank.pocnet.net/sheets/010/e/ECC83.pdf Thanks for the link and page number. I've learned something new. So the max cathode to heater voltage on a 12ax7 is 180V. So now with my changes it's about 120V difference (177V-58V). That seems better. Anything else look out of...

I added a parallel 220K Resistor to bring the heater elevation down to +58V:

Thanks so much for chiming in everyone! I didn't have any 2W 47K resistors so I experimented with a 68K. Is this excessive? It gave me 72VDC elevation for the simulated heater ground. I can do some parallel or series resisters to get a different value if desired. Here are my new voltages in green wi...