# Traynor Guitar Mate -- Muddy & Muffled



## paraedolia (Nov 26, 2008)

I have an old Traynor Guitar Mate YGM-2, and it's really muddy sounding...sounds like it's got a big blanket over it unless I hit the treble boost. I swapped out the crappy old speaker for a Celestion but it's still just as bad. The treble and bass pots don’t really do much — actually the bass pot does nothing at all. 
I just got it back from a local tech who got rid of the death cap and replaced the cord. He said he changed the bright cap (can’t remember the values) to make it a bit warmer sounding — but it’s not warm it’s muddy and muffled. The tone pots didn’t do much before he fiddled with it though, so there’s more to it than just a cap.

Q. Would bad pots do this? Can I just fire in a couple of new 250k Linear (from the schematic) and see? (Will I kill myself in the process?)
If it’s not the pots, what else could do that? 

FWIW I ran it into another speaker cab and it sounded the same — muddy/muffled. Ran another amp into the speaker from this one and the speaker sounded fine. 

Should I just take it to another tech? It sounds awful.


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## hollowbody (Jan 15, 2008)

paraedolia said:


> I have an old Traynor Guitar Mate YGM-2, and it's really muddy sounding...sounds like it's got a big blanket over it unless I hit the treble boost. I swapped out the crappy old speaker for a Celestion but it's still just as bad. The treble and bass pots don’t really do much — actually the bass pot does nothing at all.
> I just got it back from a local tech who got rid of the death cap and replaced the cord. He said he changed the bright cap (can’t remember the values) to make it a bit warmer sounding — but it’s not warm it’s muddy and muffled. The tone pots didn’t do much before he fiddled with it though, so there’s more to it than just a cap.
> 
> Q. Would bad pots do this? Can I just fire in a couple of new 250k Linear (from the schematic) and see? (Will I kill myself in the process?)
> ...


That depends what you took it to the first tech for. If he was supposed to do more than just add a 3-prong and remove the death cap, I'd be asking him what's up with your amp. He should have noticed that your pots weren't doing anything and replaced those before he went and started fiddling with the circuit.


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## Wild Bill (May 3, 2006)

hollowbody said:


> That depends what you took it to the first tech for. If he was supposed to do more than just add a 3-prong and remove the death cap, I'd be asking him what's up with your amp. He should have noticed that your pots weren't doing anything and replaced those before he went and started fiddling with the circuit.


Pots are not active devices. That means they're not doing anything complicated inside to change the tone. They are simply a variable resistor. They need to be wired in a specific way with other parts to change the amount of bass or treble. If a pot stopped working you would hear no change in tone at all as you rotated it. You might lack or have too much treble or bass but it wouldn't CHANGE the tone to be "muffled and muddy".

So you can replace them but I seriously doubt if that will solve the problem. 

There are a whole passle of things that can be causing this problem. Bad caps, a bad resistor somewhere, a problem with a tube - you could guess forever but what needs to happen is to have a tech actually get out some test equipment and start troubleshooting. By yourself you can try swapping out tubes with known good ones to see if one is bad. I wouldn't just replace all the tubes. That's like having a problem with your car and replacing all the pistons. Expensive and they may not be the problem anyway.

Did the tech check the tubes? A good tech will always have a tube tester or two around his shop. 

Sometimes the cathode power resistor for the EL84/6BQ5 output tubes gets old and drifts badly in value. This changes the bias and can also make the sound muddy. Simply checking if it has changed its value with a multimeter will tell if this is the problem. Also, old electrolytic caps can do this. The big ones in the power supply make still be keeping down the rectified hum but the little ones in the preamp stages also dry up as they get old.

As I said, there are so many things that we could guess all day. It's like a couple of guys looking at a car that won't start, wondering what could be the problem. Sooner or later someone is going to have to get out some tools and go under the hood.


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## madkatb (May 14, 2009)

When I started reading this thread my first thought was caps but Wild Bill nailed all the possibilities. Try the tubes first. Have your tech check the bias resistor value on the output tubes. 
The reason I thought caps was cos I just recapped a Super Reverb and the owners immediate response, after playing two chords, was "bright and shimmery with fuller bottom end". Sounds like what you're missing.


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## hollowbody (Jan 15, 2008)

Wild Bill said:


> Pots are not active devices. That means they're not doing anything complicated inside to change the tone. They are simply a variable resistor. They need to be wired in a specific way with other parts to change the amount of bass or treble. If a pot stopped working you would hear no change in tone at all as you rotated it. You might lack or have too much treble or bass but it wouldn't CHANGE the tone to be "muffled and muddy".
> 
> So you can replace them but I seriously doubt if that will solve the problem.
> 
> Did the tech check the tubes? A good tech will always have a tube tester or two around his shop.


Sorry for being unclear Bill, but what I meant was that if he was commissioned to give the amp an overhaul, he should have been thorough enough to notice that the pots were wonky in addition to going around fixing what needed doing. I recently took my JTM45 for some minor mod work and biasing and my tech noticed that I was running the wrong value of fuse. I had bought the amp second-hand and never even thought of checking the fuse (who does!), but my tech did and I'm glad because the value was waaaaaaaaaaaaaaaay off!


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## paraedolia (Nov 26, 2008)

Thanks for all the info -- I asked him to do the deacth cap/3 prong thing mainly and rebias it, which he did. I pointed out that the treble and bass pots weren't actually doing anything and could he have a looksee, check caps too. It came back with full checkup, changed the bright cap to make it a bit warmer everything AOK. But it sounds to me like it's got a huge blanket over it. Think I'll take it to another tech for overhaul. Cheers


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## Wild Bill (May 3, 2006)

paraedolia said:


> Thanks for all the info -- I asked him to do the deacth cap/3 prong thing mainly and rebias it, which he did. I pointed out that the treble and bass pots weren't actually doing anything and could he have a looksee, check caps too. It came back with full checkup, changed the bright cap to make it a bit warmer everything AOK. But it sounds to me like it's got a huge blanket over it. Think I'll take it to another tech for overhaul. Cheers


RE-bias? The YGM-2 is a cathode biased amplifier. There IS no bias adjustment to be made! So what did he do?

Did it sound better before he changed the bright cap? Bright caps leak in more treble at lower volumes and stop adding anything at about half volume and up. They're necessary because the human ear isn't as sensitive to treble at low volumes so unless you're playing loud your ear needs a bit of treble boost. How much boost will make a big difference in tone. Maybe you'd like the bright cap put back to stock?

Also, did you actually ever hear this amp sound the way you think it should before anyone worked on it? Do you have anything to compare it to?

I had a guy with a YGM-3 who had the same complaints as you. Oddly, after I had given him back the amp he took out the Orange Drop coupling caps I had installed and put the original cheapo "mustard" caps back in. He swears the amp now sounds great!

My ears don't agree and neither does anything I've learned in about 48 years of studying electronics but hey, if he's happy then who am I to argue?

Did he actually check the tubes? Did he check that the voltages on the tubes were in the ball park? What you've told us so far is pretty vague for what a real tech would do...


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## paraedolia (Nov 26, 2008)

Wild Bill said:


> RE-bias? The YGM-2 is a cathode biased amplifier. There IS no bias adjustment to be made! So what did he do?


Hmmm, I read that somewhere, but I’m not clear what it actually means. He said something about “lowering” the bias…



Wild Bill said:


> Did it sound better before he changed the bright cap? Bright caps leak in more treble at lower volumes and stop adding anything at about half volume and up. They're necessary because the human ear isn't as sensitive to treble at low volumes so unless you're playing loud your ear needs a bit of treble boost. How much boost will make a big difference in tone. Maybe you'd like the bright cap put back to stock?


Yes.



Wild Bill said:


> Also, did you actually ever hear this amp sound the way you think it should before anyone worked on it? Do you have anything to compare it to?


Yes I played it a couple of times for an hour or so each time, but got a (mild) shock off it so off it went to have the 3-prong installed pronto. I got a nasty belt off an old amp years ago so I’m fairly cautious now. 
I’m also comparing it to the 1970s YGM-3 sitting next to it (and subconsciously to every amp I’ve played over the last 30-odd years I guess). Just to make sure it wasn’t the speaker, I crossed the speaker cables from the two amps too — it’s definitely the amp that sounds blanketed as it did so into the other speaker (and its speaker sounded fine driven by the YGM3).



Wild Bill said:


> Did he actually check the tubes? Did he check that the voltages on the tubes were in the ball park? What you've told us so far is pretty vague for what a real tech would do...


He said so…

He’s not a ‘real’ amp tech I guess, but a local guy who builds studio equipment. I’m just going to take it to the local amp guru first chance I get as you've convinced me this isn't something simple I can fix.


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## Wild Bill (May 3, 2006)

paraedolia said:


> Hmmm, I read that somewhere, but I’m not clear what it actually means. He said something about “lowering” the bias…


Biasing an amp refers to setting the idling current in the output tube(s) to a specific amount, similar to setting the idle speed in a car. If it's too low the sound gets thin, tinny and the output drops. If it's too high you harm the tubes.

You need to set the grid negative with respect to the cathode to control the idle current. Most amps have a fixed negative voltage supply to do this, usually with an adjustment control to set things to the "sweet spot".

Some amps use a different method. They insert a large power resistor from the cathode of the output tube(s) to ground. Since this is in the output current path, there will be a voltage drop across this resistor. This will make the cathode positive with respect to ground, which will be the same as making the grid negative with respect to the cathode.

There is no adjustment! You design around the right resistor value to give you the right bias voltage for the desired idle current. The only way to adjust a cathode biased amp is to change the value of that cathode resistor. This can be a very confusing thing for a novice, since the circuit has a tendency to compensate. If you lower the resistor value the current will go down, decreasing the voltage drop. This however means the amp has a lower bias voltage, making the tube want to INCREASE the amount of current flow! If you don't understand what's happening you can easily end up with the idle current very far from the proper level, which WILL affect tone! It can also prematurely burn out your tubes.

You might want to look at the output tubes while the amp is on and the room is dark. You should plainly see the heaters glowing at the top and bottom of the tube elements under the glass but make sure that there's no "hot spots" glowing red, orange or worst of all white on the sides of the element! This is a classic sign of too low a bias level and the tube is trying to burn itself out. This could be the case with your amp since the problem also makes the sound muffled and muddy.

To make things even more confusing, Traynor wasn't always consistent with keeping up the paperwork to changes on the production line. It's not 100% guaranteed that your YGM-2 is cathode biased. You need a tech to take a look.


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## Geriatricrocker (Jul 20, 2009)

It's an old amp, the caps were top quality , but now it's 30-40 years old and they're due. The pots are probably corroded as are most of the solder joints, I'd resolder the entire terminal board and change the caps, clean the pots. And if the sound that muddy I'd check V1 and V2 , they are probably weak causing a loss of highs and lots of muddiness. It's normally a clean sounding amp when well maintained.


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## thehoj (May 12, 2009)

Wild Bill said:


> Did it sound better before he changed the bright cap? Bright caps leak in more treble at lower volumes and stop adding anything at about half volume and up. They're necessary because the human ear isn't as sensitive to treble at low volumes so unless you're playing loud your ear needs a bit of treble boost. How much boost will make a big difference in tone. Maybe you'd like the bright cap put back to stock?


When I first got my YGM-2 I snipped out the bright cap and changed one other cap to then brighten things up a bit to sort of get a middle ground to it's original brightness and being too dull.
With the treble boost engaged it sounded good, but without it was also super muddy sounding.. 
Recently I decided to put the old mustard caps back in including the "bright cap" this made the amp much more usable without the treble boost, but just obscenely bright with treble boost engaged. So I took a different route this time, and changed the cap on the treble boost from a .001uf to a 250pf, I also made the down position of the treble boost (previously off) engage a 120pf cap over the volume pot.
I feel like I've got much more useable tone now.

With regard to the biasing of this amp, I'm sort of confused as well, All of the schematics I found seem to indicate that the power tubes are indeed cathode biased, but when I had the amp open this time I took a look at the cathode pins on the power tube sockets and could trace pin 3 of both power tubes directly to ground.. I probably should have tried to look into this further, but the amp sounds so good, and I'm pretty sure the power tubes are running where they should be so I figured I didn't need to mess with it.
At some point I should figure that out though.


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