Odd normal vol channel..

[The Captain]

Hi- sorry me again, enjoying my 5e3 handiwork- BUT Q re normal 'bassy' vol/ no gain.. the normal vol seems like a 'bass pot' rather than adding anything useful to the bright vol, & also I can't get any gain at all (albeit not cranked, but jamming vol say @2.5 on bright vol adding anything up to 10 say with normal vol pot). Guitar into normal inputs is just 'bassy' without any useable tone whatsoever..

Ive done the cap changes to help (bright pot is ok and useable, really tho only with an EQ pedal's bass end way down) but normal side just sounds like a guitar tone knob at 0- bass only: no use at all). I do have a tad 5y3gt (I get 388v plate V) and a 12ay7 for 1st tube. All other voltages, wiring etc checked and ok.

In short.. 1. is the normal vol meant to be this way?? 2. can I change any other caps else to brighten/ cut any bass 3. Any thoughts on why I cant get gain? (I built it for the overdriven tones!). thanks Captain.

[sportster4eva]

Hey Capn',
That's definitely not the way the normal channel is supposed to sound. It's definitetly not bassy, unless you roll the tone knob back to about 2. The way the two channels interact is that when you're plugged into normal 1 input, turning up the channel 2 volume starts to fatten up the tone as you progress towards 12, and vice versa. I'm thinking maybe you could try only wiring up the normal and bright channel 1 inputs only, like Stokes suggested in the other thread, and see what that does.

[The Captain]

I defo have all 4 inputs wiring ok now, all other wiring too.. have checked voltages: yes high at pin 3 of both 6v6gt's (388v), but others all Id say are reasonable. The only thing I did different is to wire the tone's .0047 cap to gnd lug of adjacent bright vol pot; I can't see that as being cause for this bassy business tho? Ive been advised to switch my cheapo 5y3gt out and my 16uf/ 475v caps are cheapo too- again I cant see either being the cause.. could a sino 12ax7, or a dodgy one (no obviously noisiness mind you) for that matter do such shenanigans? Im sure the normal channel should be only a wee bit 'darker' to the bright as a general rule, so I defo have an oddity here it seems..? Captain.

[RickyD]

Captain-

Before you try anything else, I suggest you take a chopstick and tap on all your solder joints while the amp is on. If the joint makes noise, melt it again. If your problem is a bad solder joint, you'll be done in ten minutes.

If you've got spares, exchange your preamp tubes.

The gain curve should be identical for both channels, the only difference is more treble in the bright channel. I don't understand your description of the gain problem, so let me give you an example. On my 5e3, using a telecaster with vintage style pickups, I reach full volume at 2 - 2.5 on the volume pot. Are you doing that on either channel?

Regards,
Rick

[stokes]

Yeah,Cap'n something aint wired right there.Both my clones are like Rick and sportster described more or less.I would suggest looking at the tone caps,in particular the .0047 you mentioned,I dont think the rectifier or any of the other changes you mention will help this problem,this definately is a problem in the tone/vol circuit,I suspect that .0047 cap is tied to the wrong lug of the volume pot,making the volume act as a tone control,as you describe.

[The Captain]

Cheers folks- oddly that .0047 is tied from tone to the bright vol pot thats sounding, well ok I guess. Ive got correct continuity all around circuit too.. could a dodgy vol pot do this bassy baloney?

[MWJB]

Sportster wrote: "The way the two channels interact is that when you're plugged into normal 1 input, turning up the channel 2 volume starts to fatten up the tone as you progress towards 12, and vice versa."

That's not the way any 5e3's I have worked on behave, nor do I believe that this is normal. Usually, as you get the unused volume (the one you are not plugged into) past halfway (max gain), gain starts to drop off again and the tone cleans up, mids are scooped. This may not be the case, however, if you have converted the volume controls to voltage dividers or installed Bruce Collins' mod.

The difference between the 2 channels in a stock 5E3 is that 500pf cap from the wiper of the Bright vol to the RH tab of the tone, this cap does not feature in the Normal channel and typically makes that channel duller until you get it turned up enough to cut.

However, gain should be about the same for both channels, but the voicing can make this tricky to determine by ear.

To reduce bass further (it sounds like you could do with losing some from the Bright channel too if you need an EQ pedal) I would look at your 25uf preamp cathode bypass caps, you could either replace them both with 4.7uf, or keep 25uf in the first stage (V1) and stick a .68uf (1uf may be easier to find and you don't need to stick to electrolytics, a non-polarised metallised poly cap of 25v rating or better will do) in parallel with the 1500 at V2 pin 3 (keep resistor values the same). Or experiment until you find what suits you. Bass reduction through cathode bypass caps will affect both channels, unless you split the cathodes at V1 and give pin 3 and 8 their own cap & 1500ohm resistor (not usually necessary).

Subbing the 12AY for a 12AX7 will give you more gain, but typically stodgier bass too unless you play with the preamp cathode bypass cap values.

[sportster4eva]

Originally Posted by MWJB

Sportster wrote: "The way the two channels interact is that when you're plugged into normal 1 input, turning up the channel 2 volume starts to fatten up the tone as you progress towards 12, and vice versa."

That's not the way any 5e3's I have worked on behave, nor do I believe that this is normal. Usually, as you get the unused volume (the one you are not plugged into) past halfway (max gain), gain starts to drop off again and the tone cleans up, mids are scooped. This may not be the case, however, if you have converted the volume controls to voltage dividers or installed Bruce Collins' mod.

Sorry for the misconception, what you described is what I meant when I said fattens up the tone. The scooped mids is what does it.

[The Captain]

Ok, Ive ordered a .68uf O drop for that V2 bypass cap, and ill stick the 25uf back for V1 bypass. Ive got both at 4.7uf at the mo, but they made barely any difference to the normal channels bassy bafoonery. Also got a EH 12ax7 ordered so then I can see if either tubes are dodgy, along with 3 Sprague Atom main filter caps, & a SMica 680pf for that 500 tone one. Hope that lot does summat! Ill post results- After that, is an innefficient spkr like a 93db jensen alnico rather than my 100db eminence (which is loud and 'hard' sounding) an idea to hopefully get at least a hint of overdrive?? (or 'gain' as i prob wrongly termed earlier; distortion basically). Many thanks for the tips all. Captain.

[stokes]

Yeah I have always thought of it as a scooped mid thing,but just figured it was sportsters perspective or different way of describing it,didnt seem to matter to this issue,it seems to me that a volume pot acting as a tone control has to be related to the way it is wired as opposed to a tube issue.With a stock 5E3 the distortion should come up rather soon as the volume is turned up to about 3.Does your Bright channel work normal?

[The Captain]

Bright channel sounds ok (tho I still use a boss eq to rid the bass)- but I get zero distortion even with this channel: so say even with a boss eq level at 1, guitar vols down a tad to ratchet the 5e3 to 3ish on the bright vol= still clean as a whistle?!

Incidentally, does anyone know what the addition of a .001 to the 100k as a bypass (from pin 6 of V2) do? perhaps it could help my bass bunyons.

[MWJB]

This will bleed off highs, probably not what you want.

[The Captain]

Ok I'll leave that then MJWB.. if I were to change that .0047 on the tone pot to a .01 say, would that brighten or darken things do you think; is it ok to play about with different bypass caps, tone pot caps etc?

[MWJB]

A larger cap to ground from the tone pot will bleed off more highs, darken the amp.

Play with whatever you want, it's your amp and it's got to do what you need it to do, irrespective of whether or not that's the way it was designed. Typically though tone cap values seem to end up as stock (though some older amps used .0033uf to ground)?

Perhaps another place to look might be the .1 coupling caps that feed the power tube grids, if the amp is too bassy these can go down to .047uf, maybe too bright with a solid body Fender guitar, but this is the kind of value that Gibson used in similar amps.

[The Captain]

Ah thats interesting, that could be my last port of call short of changing the spkr- and thats quite a hassle and expense. It is a twin humbucker sg Im using it for after all so any gibson amp tips may be a way to go- cheers capt.

[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]

Originally Posted by sportster4eva

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!!

[stokes]

No need to post the volts if MJWB said they are okay,then I am sure I wont see anything there.I just went down and checked mine as you described and when plugged into the bright input with that vol on zero or off and turning up the normal volume I get a dull,bassy muddy tone with very little volume and I have to wonder if this is what you have been describing yours sounds like.Again I have to say that speaker should be okay with that amp,I dont think a speaker change is going to help,the first speaker I had in mine had an Eminence Legend and it was fine.A 5E3 that is wired correctly is going to sound decent if not "ideal",and may require some tweaking to get it to your liking,but it will definately not exhibit what you are describing.I still have strong suspicions about your inputs,I hate to sound like a broken record about these inputs but you did have a problem earlier there,to simplify things in that regard I would again suggest disconnecting all your inputs and wire just one input to the brite channel with a 1meg from the "hot" lug to ground,a 68k in series to the input grid of the 12AY7 and the shorting switch grounded.This will make your input as simple or basic as can be,if the amps response improves,you have your problem solved,if not you can move on to another stage as you have discounted that "stage" as the problem.Gotta go one step at a time,and starting at the beginning is the best way

[The Captain]

I did redo the inputs, so now no. 1 is tighter and a tad louder sounding than no.2 on each channel (all have 1M checked) but with your point taken on board Ill strip them to one each tmrw. As to your help re my Q above Mr. Stokes that muddy dull sound is exactly what I have- but it sounds just like this on normal input/ normal vol, or with this vol at 0 and bright vol at 2ish.. so Im nearly convinced then that its the way its meant to be. I noticed that the tone is brightest at 9 tailing off again up to very dull again at max on normal channel, is this the norm too?

So, if you and others suggest the speaker should be ok although Im only getting little at best blatty, hard overdrive even with either vols (or both vols) high -then could the OT could be a weakness? I also read a certain better quality 5y3gt's blurb.. 'good for low headroom' etc: I didn't think the rectifier was determinant of clean headroom, rather having 2 12ax7s was the idea on this.

Thanks for the advice all- frustrating as this has been Im much happier knowing I can spiel with intelligent advice in reply. Im very reluctant to give up on this- heck I even made a flight case for it- so Ill crack on again tmrw.

[MWJB]

To check your speaker (& eliminate from our enquiries), pull the jack from the chassis (amp off of course) and put a 9v PP3 battery accross the jack plug terminals, one terminal to the barrell of the plug, the other to the tip. On connection you should hear a definite crack, if you're in doubt as to whether you hear anything, or you just get a quiet, dull "tick" then maybe your speaker is suspect BUT, as Stokes says, an Eminence 125 should be absolutely fine for your amp if in proper working condition.

If the OT was the weakness I would expect a fuzzy, "radio" like tone with no cleans whatsoever. This is not what you have been describing.

5Y3 - different brands may result in differing final voltages (more volts = more headroom) and a different envelope of the note (intensity of attack & decay). lots of factors contribute to clean headroom, rectifier is just one of them.

Don't give up.

[Bruce / Mission Amps]

Originally Posted by The Captain

As to your help re my Q above Mr. Stokes that muddy dull sound is exactly what I have- but it sounds just like this on normal input/ normal vol, or with this vol at 0 and bright vol at 2ish.. so Im nearly convinced then that its the way its meant to be. I noticed that the tone is brightest at 9 tailing off again up to very dull again at max on normal channel, is this the norm too?

Assuming you are describing this condition accurately, nope, I still think something is not right.
However, the actual tone control is across the bright channel's volume pot so it's effectivness is limited, with respect to the normal channel volume pot.

The correct norm is this....the common cathode of both triodes of the 12AY7 allows the unused triode to be heard when plugged into the other channel and the two volume pots are wired in parallel, effecting each other's channel.

That unused channel, in a weird way, becomes a cathode driven preamp.
In other words, the common cathode resistor slightly modulates the unused channel's cathode by the signal from the one you are actually using.
Confusing?
Try this, plug into the bright channel and shut it's volume control down to zero.
Now, turn the normal channel's volume control up all the way and strum some chords (while plugged into the bright channel) and you will hear a low volume level, muddy tone that is about 1/4 the volume level of the actual channel you are plugged into, but there is very little treble response.

You can use this effect to alter the tone of the bright channel you are plugged into and this effect is part of the interactive volume controls peopole either love or hate.
In conjunction with the odd "cathode driven" preamp effect of the 12AY7 wiring, the two volume pots are also wired in parallel.
Signal is fed into the vol pots through their center lug, the wiper.
So when you turn the unused volume pot up while being plugged into the other channel, signal leaks over the top of the pot and you start loading down the "used" channel's signal path, shunting some of the audio to ground through the unused channel's volume control to it's 100nF coupling cap and over to the actual B+ supply filter cap, which is grounded.

[The Captain]

I think then I may be in the hate camp! Ive a better understanding of the pots now thanks Bruce. I'll look into that dual gang pot job I think (as per the s2 5e3); its also meant to help the quick ramping too- but this later- 1st I need to find out how/ if I can get any distortion with the useable bright channel. So
1. Im gonna ditch the plastic jacks for switchcrafts and install one each channel for the mo.
2. scratch my head again as to why barely any distortion/ check all wiring for 8th time.
3. ditch my mdf cab/ chipboard baffle (prototype) & make a pine cab/ ply baffle to help the general tone.
4. get this 5y3gt as it has 'good lower headroom' http://www.watfordvalves.com/product_detail.asp?id=94 ('sag' whats that?)
5. trim my beard.

here are my scribbled voltages:

Pin 3 (both pwr valves)= 389v/ 388v
Pin 4 screen= 341v
Pin 6 plate (preamp?)= 193v
Pin 1 plate= 155v
Power supply= 247v
Pin 6 (12ay7)= 126v
Pin 1= 121
Preamp cathodes= 2.04v, and 1.28v.

cheers, captain.