The Amp Garage

image.jpeg image.jpeg image.jpeg image.jpeg I can understand the safety resistor on the bias pot, but not the diode as shown. Since it's working, maybe you haven't drawn the bias supply as-built? Martin, I looked back at Merlin's book and the extra diode in the bias supply is to slow down the disch...

I agree on Merlin's grounding. I had to go back to his article several times(I'm a little slow) but once I got it, it made perfect sense! My interpretation is that it's all about controlling where currents travel and thinking about each node in the power supply as a separate power supply. Now I have...

The loop seems to be working well. I have only had a 15' instrument cable in the loop so far and a crappy autowah because that's what I have around and all functions appear quiet and stable. I screwed up and put in an audio pot for the mix control so there's a bit of a hump but it's staying for now....

I just read the thread on detuned cabinets. I heard descriptions of wall shaking bass caused by speaker/cabinet problems. I think that's where I need to start looking.

The bias supply is built as drawn. I'll take another look in Merlin's book to refresh my memory on the extra diode. I can easily add the balance resistors at B+2. To be honest, at that stage in the supply I didn't think I'd need them. As far as the later stage filtering, I wanted to try the lower ca...

Thanks for noticing the missing connections in the schematic. They are physically there in the amp. The bias supply is borrowed straight out of Merlin's book and from my understanding of the text the extra resistor is a safety in case the pot wiper ever failed. I'm not an EE so I rely on the work an...

45 watt project.bmp So, I've been thinking about this one for a long time and started the project almost as long ago. Right now, the amp is fairly quiet and stable even with everything maxed and sounds pretty good. This is my fourth build and the goal was to try a bunch of stuff that I have seen on...

FWIW, this is the amp forum that I keep coming back to. I also think the traffic is picking up as well. Trainwrecks and Dumbles still appear to be the primary focus of the forum judging by the number of posts in each section. Change is inevitable, but I think it's great to hear from new people with ...

I ordered an MC output trans and impedance selector switch from triodestore about 4 years ago. The transformer arrived ok, but I think it took about two months to get the switch! Luckily, I too am a slow builder. I just ordered and received a transformer from amp parts and it arrived in a few days (...

That amp is built and gone. My nephew is using it. I'm planning the next one. I started this post to get a feel from more experienced builders on whether the topology I had used was an obvious poor practice. I'm moving on to a 40-50 watt with fixed bias because of haven't built one yet. I want to bu...

I'm not sure how much gain. I don't have the schematic handy, but the pentode was fairly warm biased and being fed with about 200 volt B+. The first stage has a 33k grid stopper, 220k plate resistor and red led on the cathode. It could definitely growl!

So, the amp that I built had V1a ax7 through a 500k vol. pot into a 5879 pentode direct coupled to v1b ax7 as a cathode follower. I didn't experience any stability issues, but I tried very hard to lower the hiss level at high volume and always wondered if the design contributed to the noise level. M...

Thanks for that information. I'll have to read it through a couple of times to fully digest it. I'm not sure it answers my question of having signals with a large magnitude of difference in the same envelope. I suppose that if it's a concern, I may as well avoid it in future designs.

A couple of years ago I built an amp loosely based on TW designs. The power amp was 2 x el84 driven by a rocket PI. My question is related to the preamp. The preamp consisted of an ax7 for v1a>volume pot>5879 for v2>dc coupled to v1b ax7 cathode follower>Liverpool tone stack>Power amp. I was able to...

Thanks for all the great info. That gives me good food for thought!