The Amp Garage

You really want a dedicated connection to ground through a ground lug to be safe. When you tried replacing V1 with another valve did the level of hiss change at all? Also, I would swap the master and presence controls around. It will shorten the leads for the master control a lot. In my previous it...

xtian wrote: ↑Wed Jun 29, 2022 9:30 pm
You might reduce hiss by replacing 68K grid stops with 22K or even 10K.

Ah, yes. Another something to try!

Have you checked the resistors are in the right places though? I would check through the circuit, at least around V1. i.e. Measure resistance from pin 1 on v1 to the power rail to ensure you read 100k etc. Also, where is your circuit connected to the chassis ground? I will check al of them, this we...

Heater hum doesn’t seem to be present. It has been elevated and balanced via a humdinger pot. But if all else fails, I can try. you will be surprised what us coming through the heater line. on high gain this is important. easy test take smal 6VDC lead battery pack, disconnect the V1 heaters, and co...

I've just noticed, you've got a 10K resistor between the first stage and the volume pot, that should be a 470K. Is that intentional? Not saying this is the cause of the hiss, just something I've noticed. With regards to the hiss.........This is unlikely to be a wiring issue or interference, that wo...

Could you upload a recording of it please? Turns out, I can :) https://youtu.be/5u7fYHD_8UQ So in the video I have the amp turned on. I have set the volume at 1 quarter. Way louder then I would use in my attic. First you hear the hiss, as it is the high input, unconnected. Then with a pen I activat...

What if you plug into the low input? That would eliminate the first gain stage, does it still hiss? Could you upload a recording of it please? I don’t think the hiss is there anymore, when engaging the low input. But I will verify that. I have tried to record it, but doing this with an Ipad doesn’t...

did you try what i have suggested before? put all the wires against the chassis? first stage must be silent without guitar on max volume. all other problems what you have are related to lead dress and pcb.. it is easy , several hour job, remove all from V1 and do again. dc heaters for V1 can also e...

Did you put V1a grid stopper resistor right on the tube socket (best practice)? Hard to tell in photo. What value is grid stopper? Hello xtian, Thanks for the reply, somehowe I don’t get update notifications anymore so I didn’t see you reacted. The 68k grid stopper is attached to the socket. And is...

I still have a sssssssssssssssssss problem. This hiss is gone when I pull out V1 out of its socket. Did you try different tubes in the V1 spot? Maybe you have a noisy tube. When the hiss is present I am not having a guitar connected .The hiss is the same when the guitar is connected. So it's presen...

I finished up the soldering and wiring of the amp. Version 2.0 is now working. This time based on a PCB I designed. So things are more tidy which is nice. All power supply capacitors are on the PCB, except for the first two filtering caps. Those are now placed in the outdoors. But…… I still have a s...

xtian wrote: ↑Sun Jun 19, 2022 4:51 pm Nice! Hope it sounds as good as it looks!

Thanks Xtian. I hope so!

Currently wiring it all up.

This amp turns out to be quite the journey. After my first attempt wasn’t quite perfect in terms of performance, I decided to rebuild it. when the rebuild of the preamp was done, the amp is now noise free. I had put a lot of effort into this amp build. I learned a thing or two. And that was all grea...

This afternoon I have hooked my pre-amp up to my EF80 power amp made recently. I made a little recording with my I pad. It’s not a real good recording, but it’s something to illustrate. The hum that is heard, is from my p90 pickup. When I drop down my guitar volume to 0. The amp is now silent and th...

Now I just finished the rebuild of only the preamp section. And I have finally defeated my “hiss” demon. In the end It must have been the turretboard soldering, that plagued me. I remember that I had a real tough time soldering it back then. I think I must have had a bad batch off turrets. Can’t rem...