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So my high power Princeton build is finished. I've powered it up and there are no sparks, bangs, smoke or other signs of bad things happening.
However, when I take it off standby things clearly aren't right. First of all there is a loud hiss - not massively intrusive but it sounds like the amp is turned up all the way, when in actual fact all the dials are zeroed.
Whenever I touch any of the dials it gives off an intermittent crackling and there's also what sounds like low frequency feedback through the speakers.
I have briefly plugged in a guitar and turned up the volume a little and it does amplify the signal so it kinda works but would be nice to get rid of the low frequency feedback issue if nothing else.
I am for the moment a little bit afraid of the amp so it never stays on very long while it's not working right.
All valves I've used are good but I've tried a different and known good set and the same issues persist.
Not being an amp tech, or knowing what to check, I'm clueless as to how to diagnose the fault let alone fix it and while I'm not completely stupid I don't really want to kill myself - well, it's not the way I'd choose to go should I want to check out early, let's put it that way.
I appreciate that it's going to be very hard for anyone to help properly diagnose the fault without the amp in front of them but if anyone could suggest what the symptoms might indicate then that would be great.
If anyone is a glutton for punishment and does know what they are doing then I'd also be willing to ship it off to any tFB member who might want to have a go at fixing it and if there's a fee involved then I'm happy to talk about that too.
It was a fun project, I probably should have done a few things differently, but it would be nice to have it working and useable.
Thanks in advance.
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
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Comments
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
Does the amp have power stage negative feedback? Hiss is often a symptom of having none. Feedback is often a symptom of it being connected backwards (as positive feedback), but that will usually not just be a hum, it will be a high-pitched whistle.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Wish I was, mind.
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Rift Amplification
Brackley, Northamptonshire
www.riftamps.co.uk
Thanks guys, will relocate that end of the wire and see what difference it makes.
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
So, negative feedback wire relocated and things are much quieter, although once I'd removed the reverb driver it fixed most of the noise anyway, and that low level feedback hasn't been heard since.
Still got some very loud intermittent cracking/popping, though. Sounds kinda like the amp is turned up loud with a loose guitar input jack.
I can induce the crackling/popping by fiddling with the volume knob (not tried turning the other dials) or by tapping on the chassis!!
Not left it turned on for long so haven't tried a guitar through for a while.
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
I have no idea if that means anything at all for safety purposes though!
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
There is no 'H' in Aych, you know that don't you? ~ Wife
Turns out there is an H in Haych! ~ Sporky
Bit of trading feedback here.
Diagnosis is a very different area though.
I am paying this thread a lot of attention, as I will be picking up a kit shortly from @Modulus_Amps . I have built pedals from veroboard layouts, and know the difficulty in diagnosing problems there - can only imagine an amp being tricksier. I would be truly amazed if my own kit build proceeds without a hitch, and Im sure I'll be asking questions too.
Looking forward to seeing a completed amp.
Adam