Odd normal vol channel..

[RickyD]

OK Cap, this is driving me crazy. The answer is right there waiting to be found. We know that your amp will work correctly if there are no wiring errors, the component values are correct, and you have no defective components.

I wouldn't change component values to correct the tone problem yet. There's a bad component or a wiring error that has to be found. The 5E3 is one of the greatest amps ever, stick with it. There is a community out here that is rooting for you.

If you haven't yet, I suggest you lift a leg on that tone cap you grounded to the bright volume pot. You have one channel that's acting like it has a low pass filter, fixed value and always on. The tone cap, connected wrong, could produce that effect.

Next, I would confirm that each component in the amp has the value specified on your layout diagram. Special care with the resistors and the multiplier bands (470 ohm vs. 470K ohm, etc.). Circle each component on the diagram after it is checked. (BTW, run an extra copy of the layout so you always have a clean one.)

Then, go to each solder joint in turn and confirm that every connection to that joint is as specified in the layout. Circle each joint after you check it. If you have hidden connections under the board, use a multimeter to confirm continuity.

I have done this kind of checking and found the flaw on the fourth iteration. It is so easy to overlook your own mistake...Sorry if I seem too pushy. This just my opinion.

Regarsd,
Rick

[The Captain]

Not too pushy AT ALL- I really value the reply/ tips. It does seem on the face of it to be a simple wiring error, innitially Id almost put money on it being exactly that too but alas alls defo correct: checked over 5x now. I will lift that .0047 cap straight to gnd (tone gnd to bright pot gnd at mo). Just tried a new 12ax7- not that; swapped 3 preamp tubes around too- still same.. am gonna try a .68uf as suggested for V2 bypass cap (* I presume I still keep the 1.5k paralled with it?) next. I'll get there even if it means growing a beard!

[Bruce / Mission Amps]

Something is funny in the way you described that grounding scheme for the tone pot and the bright channel vol pot.
And the way you talk about the lack of gain with respect to the volume pots... I promise you have a bad part or there is something installed wrong, regardless if you checked it 5x! ha ha.
Can you shoot me a digital picture of the three pots and the eyelet board around the preamp stage?
I've done quite a few of these and have not heard this problem yet when the amp is wired correctly and the amp is using three, 1m pots.

[The Captain]

Sure can do Bruce, cheers- Ill rustle up a pic tmrw. Actually ive just reverted back to the .0047 direct to gnd as opposed to tying it between tone's gnd & bright pot gnd lug: exactly the same. So Im now wondering if its just the way its gonna sound on normal channel. Ill next try a replacement pot.. whiskers have sprouted.

[The Captain]

Bruce here's a pic- best my digi cam can muster Im afraid, apologies:
http://i102.photobucket.com/albums/m...Picture270.jpg
Capt.

[sportster4eva]

In the pic, where's the black lead connect on the first pot? It sort of looks like it goes to the wiper.

[The Captain]

In the pic, where's the black lead connect on the first pot? It sort of looks like it goes to the wiper.

I knew my awful camera wouldn't prove so useful here! the black leads connect from tone [edit] 2nd lug (as viewed here) to bright vol 3rd lug and another to normal vol 3rd lug; the wiring is all correct to the weber layout.

So I spent today rewiring the pots in case of summat, changing the 500pf to 680pf, V2 bypass to a .68uf and all 16uf filter caps with ubiquitous Spragues 475v... without the slightest difference whatsoever! so this is the stock normal channel sound it seems.. a shame really- its completely unuseable as its just too bassy. Still can't hear a hint of overdrive either even with 2 12ax7s (maybe I could if I took out my hearing & half the street and turned it up to 8- Im still not convinced tho). A dissapointment so far this after loads of time and money.. still it does sound pretty good clean I guess.

All I need is a tone, one bright input/vol and a master vol!

[stokes]

Capn,I know you keep saying that it is wired correctly,and I cant tell otherwise from the photo, but the sound you describe tells me something isnt wired right.Either channel should start breaking up at 4 at the most,and one control should not act like a bass control,trying different value components now is futile.I again would advise using just 2 inputs it will simplify that part of the circuit and you had trouble here earlier,then go over the volume and tone circuit with a fine tooth comb,your problem is likely here.

[The Captain]

I gave it a thorough sound test at volume over wknd. Actually it sounded, I hate to say, pretty rubbish really.. very bitty, hard, uncohesive break up that never gets above a tame overdriven sound (starts about 5 and is similarish up to max- it took huge volume to get it, and a series of complaints too!) with a general big hug of bass thats just overwhelming, even on bright channel. Im sure both channels are working as intended as Ive done every check now.. I may change spkr (maybe a single 10"?), my cheapy 5y3gt and my RS 0.1ufs.. but Im wondering if its worth it now. After that its a lost cause I think Capt.

[MWJB]

OK don't throw in the towel and get disheartened now. You've probably done the hard work and it's got to be something simple, just not glaringly obvious, that's got you skuppered. Remember that the amp, for whatever reason is just doing what it is (inadvertantly) built to do, it's not being spiteful. Now that you've given it a good blast, it seems that there must be an error somewhere.

Don't worry about the 5Y3GT (it's delivering good voltage, that's not the problem), don't worry about the RS 0.1ufs, they're not the problem. The amp should give it up with the 12" Eminence.

It's not a lost cause, just have a bit more patience. You've built the thing, now you need to hone your trouble shooting skills...this is where the learning really starts!

Voltages & power supply are good, so it's something in the signal path. Eliminate things one at a time.

[MWJB]

They way you have hook up wires soldered to the back of the circuit board looks nice & neat but makes one wonder if everything goes to & from where it should. Power down, drain voltages and work through the layout, double checking for continuity from component to component using your meter set to the lowest ohms setting, highlighting off the connections as you go.

[stokes]

Like MWJB says,dont give up on it now,at worst a properly wired 5E3 should still sound decent,noisy maybe,but not at all like you describe.Hate to sound like a broken record Cap,but something is wired out of whack and you've come to far to give up on it now,I agree with MW that it is likely something simple,just not obvious,and when you do find it you will kick yourself in the butt for not seeing it sooner.That 12" Eminence should be fine with that amp and a speaker change is not what you need now.As well as the advice already given here as far as checking for continuity etc,I would also suggest you check that your coupling and tone caps arent leaking dc,and voltages at the plates and cathodes of the preamp tubes are correct."Actually it sounded, I hate to say, pretty rubbish really.. very bitty, hard, uncohesive break up that never gets above a tame overdriven sound".This description,and again you trying to describe and our perception of what you are describing can be hazy,could also point to power tubes biased cold and giving you the dreaded crossover distortion.But I still feel the tone and response you have been describing is more likely something in the preamp section.I know its tough to track down a problem in a first build,but it is part of the learning process,and all of us throwing different ideas at you can get frustrating,but dont give up,you will get there.

[RickyD]

Hey Cap-

You gotta stiffen up, man. Everybody that builds these things has episodes like this. Every misplace your wallet? Look all over the house, everyplace you can think of, still no wallet. Keep looking, find the wallet in a place you did not think possible - or realize you've been looking at it without recognition for the last 30 minutes. That's just where you are now. So close.

I jerked around with my amp for a long time, weeks. Didn't have a lot of time every day to fool with it. I finally found my problem by beating on it with a stick. No science at all. Tapping on solder joints with the chopstick for 5 minutes, found a cold solder joint, fixed it, and did't stop playing for the next three hours. If science doesn't work, beat on it with a stick!

I sense, using powers acquired in the Orient, there is a mental block forming in you. Fight it off, this is worth it. Arguably the best guitar amp in history in your hands, could be fixed and perfect in the next five minutes if you just keep after it. Sifu taught that when the body fails, it falls. When the mind fails, the body walks away. The point is that you can do this! Don't give up. I want to read about you waking up face down in the chassis. You have to do the work, and do it with an open mind. The odds heavily favor the contingency that there is a readily observable flaw right in front of you.

The fundamentals are not necessarily easy, just fundamental.

Quick recap: Correct component values, wired correctly, will work. No point in insisting it's all correctly wired. It doen't work. Your next post, I expect to see that you have taken your layout drawing and checked the required component
Just my opinion


I know a lot less than many ofn the people who post here. . I don't even know what a V2 bypass is (you changed to .68 uf, no effect).

Shouldn't changing that cap have an audible effect? What other reason to change the value now? So if you change that and can't hear a difference, does that mean maybe no signal is happening there? Should there be? You get the idea.

Did you use stranded wire or solid? If stranded, maybe an wild strand has "wandered" into a short circuit with a neighboring junction. Just for variety, try a continuity check between adjacent tube socket pins, other terminals.

[stokes]

Cap'n,I know you said all voltages are normal,but just to give us a look,would you post the voltages you are getting at V1&V2 pins 1,2,3 and 6,7,8? Power tubes pins 3,4,5,8.Maybe we will see something you are missing.I know we must have your head spinning with all our opinions and such,but bear with us and you'll get it working.

[The Captain]

MJWB kindly went through my voltages with me on the blower t'other day- a wee bit high as ive a £10 5y3; but generally fine he said. I will try and decipher my scribblings tho and post the Vs up Mr.Stokes.

Another evening's effort to sort out: (as suggested- thanks- only other day I spent 10m looking for a pen.. behind my ear!) so I did continuity checks at every possible place, and replaced the normal vol pot & the .02 cap in the normal channel from V1 in case either was dickie. I also rewired my neck humbuck to single coil- which helps a bit: but basically all as was before- all wiring correct/ solders good/ bits in right places/ polarity ok/ poss bad components illiminated now.

One obvious difficulty is not having anything to compare it to, ie a '5e3 clone shop down road' would be handy! all I have is the odd clip from Homebrew and S2 (which sound excellent, with clear distortion and certainly not a bass enveloping normal channel). Can someone tell me.. if plugged into either bright input, with vol at 0, and then introducing say 2 on the normal vol.. can anyone describe the sound heard? I mean if its like mine then Im pissing in the wind, and Im defo stuck with a turkey 5e3. I definitely have a rubbish eminence legend 125 spkr I think- cardboardy, LOUD, one-dimensional and blatty hard overdrive (if I can call it overdrive); of course Im no nearer knowing if I replaced it with say a jensen P12Q (Ive an eye on) things would be a whole lot different. It dont help either when a fender revalved red knob twin goes on fleabay for little more ££s than my concoction!!