The Amp Garage

<r><QUOTE><s>[quote]</s>Interesting. It would be revealing to see a second trace with the filament voltage, to be able to spot the relative positions of the peaks and valleys of the noise and the AC mains waveform. It seems like the noise magnitude envelopes are similar to full wave rectified sine(i...

I did take some pics of the noise today: IMG_5927.JPG This is the filament waveform without any filtering. I forgot to take one of the line all by itself but they're practically identical. The line being obviously just scaled up from what you see here. IMG_5929.JPG This is the output of the second g...

The noise is just present on the power line without the amp hooked up. Its pretty much always there and I'm not really sure whats causing it. Can you post a pic of how noisy the wall voltage is without the amp plugged in? You might've missed the bullseye when you described it, but it could still be...

Thanks for all the replies, I'll try to address everyone's points in order: -Electrostatic shield would definitely be effective in combating this issue. Unfortunately I don't know of anyone making off the shelf PT's with them included. I'm at the point now where I could fairly easily design my own b...

So as promised in my other thread here is a technique seldom seen for the reduction of heater noise. While working on my little 6v6 Express this weekend I found that a fair bit of noise was coupling into the preamp from the filaments. In this particular case it was the result of a rather large amoun...

That's certainly possible. However in the 3 2203 style amps I've done I can dime everything and not have a problem. I've never included any of the additional stability caps either. At least that's what I remember, should go back and verify that. I think it'd be interesting to see how the express beh...

Hey everyone, haven't been around much these past few years, been busy learning and designing power electronics so I haven't had much time for guitar amp stuff. Work has slowed down (for the time being) so I've been spending some time screwing around with that 6v6 express I built a while back. Its o...

Can you post a schematic? If the diode you're referring to is the one I'm thinking of then its there for over current protection and is not strictly speaking necessary. Its connected from one side of the current limiting/sense resistor to the gate of the mosfet. The way it works is, under zero load ...

Think I'd rather have the one made out of colored pencils:

https://www.youtube.com/watch?v=NmnVYSsE8NU

You might also find this helpful: https://masteryourtest.com/study/ Here's some relevant youtube channels that I subscribe to you may find helpful, some technical, some just about general music/recording: https://www.youtube.com/channel/UCU9SoQxJewrWb_3GxeteQPA https://www.youtube.com/channel/UCS0N5...

You may want to consider having one additional gain stage. I don't know what level your modeler is putting out, but standard line level is 1.4v. A standard 12ax7 gain stage will have a gain of about 60, a LTP PI will have less than that. If you're using NFB you'll have even less, which you'll want t...

This seems about right: http://1.bp.blogspot.com/-Df5m7H3Uo0Q/VSzQcAjqfWI/AAAAAAAA4i0/x96jxByoBNU/s1600/20131017-185320.jpg I moved the 470k/500p after the volume control. Seems my theory was correct. Though it didn't add as much low end as I anticipated, which is good as the amp has plenty now, may...

I love the look of those big power triodes. They sound really nice as well. 400 pounds sounds about right lol. I'd love to build one around something like that one day, but in P-P. I think the SET guys are nuts lol. I've never seen anyone go to such lengths just to get a few watts of power. We had o...

You'd only need about 2,000 of them :D At which point you wouldn't even the need the OT because the output impedance would be low enough to drive a speaker directly lmao. Edit: I couldn't help but run some numbers :P First the easy one, filament current: 1520A, which gives a power draw of 9576 watts...

You can get tubes for that here:

https://www.greenstoneusa.com/tetrodes-vacuum-tubes/