# 2x6L6 with 5Y3 rectifier?



## marauder (Oct 19, 2009)

Ok - so I have a trade offer on the table, with this tweed amp potentially coming my way. Build is of unknown origin, so I have to assume it was a homebrew based on internet schematics or similar. Owner claims it to have about 15W power output. Best as I can tell, it is possibly a Fender Bandmaster or Pro clone, modified for lower output? What gets me though is that it is running two 6L6WG power tubes, with a 5Y3GT rectifier. I'm by no means versed in tube amp design, but I've always thought that:
1) Two 6L6's are generally reserved for higher power (say 30+ watts) amps.
2) They would typically be paired with a 5U4 rectifier

So, the question is, does the combination make sense to you amp gurus? Is the circuit possibly "starving" the 6L6's to get the power down, and suitable for the 5y3? I have no info on the OT - all I have is the pic. Will be checking the amp out in person later this week - is there something I should be looking for, such as extreme heat or anything?

Oh, if you're interested, the controls are (from left to right in the pic) Presence, Bass, Treble, Vol. Bright, Vol. Normal. Dual inputs for both bright & normal channels.

Gut shot from the current owner (preamp tubes are 12ax7, not sure what the PI is):


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## nonreverb (Sep 19, 2006)

An amp could be designed with 6L6's and a 5Y3 although not something one would see often. Power transformer looks pretty hefty....my guess is it's supposed to be a 5AR4 but I could be mistaken. 



marauder said:


> Ok - so I have a trade offer on the table, with this tweed amp potentially coming my way. Build is of unknown origin, so I have to assume it was a homebrew based on internet schematics or similar. Owner claims it to have about 15W power output. Best as I can tell, it is possibly a Fender Bandmaster or Pro clone, modified for lower output? What gets me though is that it is running two 6L6WG power tubes, with a 5Y3GT rectifier. I'm by no means versed in tube amp design, but I've always thought that:
> 1) Two 6L6's are generally reserved for higher power (say 30+ watts) amps.
> 2) They would typically be paired with a 5U4 rectifier
> 
> ...


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## Wild Bill (May 3, 2006)

A 5Y3 is definitely too light duty for 30+ watts. The 5AR4 suggestion is a good one.

Still, we don't have enough info to tell for sure. First off, what is the plate voltage? Changing tubes alone will NOT result in more power out! 

The plate voltage, the available current from the power supply and the amount of drive all determine the power output. Once you've decided on those factors you have to pick tubes that can HANDLE that power level! If you have only 400 volts and a smaller power transformer suitable for 6V6s, you get 6V6 type power levels. If you put in 6L6s you STILL get 6V6 power levels! The bigger tubes just loaf and run cooler!

So maybe someone just stuffed the larger tubes in there, not knowing what he was doing? Using 6L6s and a 5Y3 would seem to confirm that.

So first off, find out the plate voltage on those output tubes. Then find some amp that uses 6V6s and another that actually puts out the higher power with 6L6s and look at the transformers. See how their size compares to the trannies in YOUR amp!

Once you know those things we can all take more educated guesses as to the capability of your amp.

I guarantee, if the amp truly was designed to run 6L6s at their type of power level the transformers will also have to be big enough to handle the higher power level. An output trannie for 6V6s will be guaranteed to burn out if it is trying to handle 6L6 type power levels.

Wild Bill/Busen Amps


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## marauder (Oct 19, 2009)

Thanks - though I can't answer the voltage questions (it's not my amp...at least not yet), what you're saying makes sense, and essentially what I meant by "starving" the 6L6's. Owner says he's been using the amp for over a year, so I'd assume that he'd probably have fried the rectifier by now if it was being fed too much juice. 

I can only guess that whoever built this wanted the tone of a larger tweed amp design at a lower wattage, so left the pre/power tubes per the original circuit, and tamed the voltages going in to them. I'll have to wait and see how this affects the resulting tone...


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## WCGill (Mar 27, 2009)

5U4GB would work as well. That 5Y3 is too small.


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## marauder (Oct 19, 2009)

WCGill said:


> 5U4GB would work as well. That 5Y3 is too small.


After doing some searching, I've read that the Sovtek 5y3, which is in this amp, is different than a "typical" 5y3 (higher current rating and lower voltage drop) - maybe that's how they are getting away with it (likely coupled with the 6L6's running colder)? So, without knowing the actual numbers, it may be possible that replacing the current 5Y3 with another brand could lead to problems. Also, from what little I know, I can't simply swap the 5Y3 with a 5U4 without some adjustments (direct vs indirect heating, and input capacitance), correct?


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## dcole (Oct 8, 2008)

Have you asked him, nicely, his reasoning for using 5Y3 with the 6L6WG tubes?


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## marauder (Oct 19, 2009)

dcole said:


> Have you asked him, nicely, his reasoning for using 5Y3 with the 6L6WG tubes?


No, because the current owner isn't the builder


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## nonreverb (Sep 19, 2006)

Dunno about that...I wouldn't risk a 5Y3...(even the old military JAN ones) in an amp designed for a 5U4 or 5AR4. You're simply asking for trouble. Has anyone else noticed that the Sovtek 5Y3 looks similar to the Sovtek 5AR4? 
Consequently, I've had to replace a couple in the past that grenaded as they were in amps designed for 5AR4's.



marauder said:


> After doing some searching, I've read that the Sovtek 5y3, which is in this amp, is different than a "typical" 5y3 (higher current rating and lower voltage drop) - maybe that's how they are getting away with it (likely coupled with the 6L6's running colder)? So, without knowing the actual numbers, it may be possible that replacing the current 5Y3 with another brand could lead to problems. Also, from what little I know, I can't simply swap the 5Y3 with a 5U4 without some adjustments (direct vs indirect heating, and input capacitance), correct?


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## Cups (Jan 5, 2010)

Could be a modded 5e3. People try to squeeze 6l6's in them all the time.


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## nonreverb (Sep 19, 2006)

Strange....wouldn't be much of a 5E3 then would it.



Cups said:


> Could be a modded 5e3. People try to squeeze 6l6's in them all the time.


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## marauder (Oct 19, 2009)

Cups said:


> Could be a modded 5e3. People try to squeeze 6l6's in them all the time.


With the presence, bass and treble controls, it doesn't really seem to fit the typical 5e3 mold. The layout of the eyelet board looks reasonably close to the Bandmaster layouts online. I really wanted to fetch a 5e3 though...

I think I'm just gonna check it out, and see if I like the sound. If so, haggle a little on the value so I can then take it to a proper amp tech for verification.


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## ampaholic (Sep 19, 2006)

The 5d8 Twin used 6L6's and 5Y3, albeit a pair of them to crank out 25 watts.


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## Milkman (Feb 2, 2006)

Seems to me I've heard that Neil Young uses a 5e3 modded to use 6L6 power tubes.

Anyone?


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## Wild Bill (May 3, 2006)

Milkman said:


> Seems to me I've heard that Neil Young uses a 5e3 modded to use 6L6 power tubes.
> 
> Anyone?


Yes he does, but it's not what I would call modded. Rather, he uses a boost pedal to drive the hell outta it and to keep the trannies from burning out from being so badly overdriven his roadies have a number of fans blowing on the back of the amp!

Even then, he's lucky to get through a whole gig without frying at least the output transformer. For him, this is not a big deal. His techs replace it and the next gig they do the same thing again!

Neil likes the sound he gets and considers burning out the amp to be an acceptable price to pay. If anyone else has the money and knowhow to keep replacing the trannies they of course can do the same thing but for most of us this isn't very practical.

Wild Bill/Busen Amps


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## parkhead (Aug 14, 2009)

#1 how does it sound... cuz that's all that matters 

#2 is the price less than the parts cost 

#3 can you take it apart and sell the parts for more than your cost ? 

#4 why not buy an amp you like ? 

p


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## marauder (Oct 19, 2009)

yeah, I'll just go by sound. I was just trying to gather info so I don't end up with something that will fry in a couple of weeks. And as much as I'd like to just buy the amp I want, I'm using this transaction to cash out a little and put a few hundred bucks back in my bank...buying what I want will put me further in the hole


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## Milkman (Feb 2, 2006)

Wild Bill said:


> Yes he does, but it's not what I would call modded. Rather, he uses a boost pedal to drive the hell outta it and to keep the trannies from burning out from being so badly overdriven his roadies have a number of fans blowing on the back of the amp!
> 
> Even then, he's lucky to get through a whole gig without frying at least the output transformer. For him, this is not a big deal. His techs replace it and the next gig they do the same thing again!
> 
> ...


Wow. Although I'm not a fan of his electric guitar playing, his tone is definitely intense.

I guess the most realistic way to get a sound like your amp is at its limit is to push it there.

Neil has somewhat deeper pockets than I do.


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## ampaholic (Sep 19, 2006)

Wild Bill said:


> Yes he does, but it's not what I would call modded. Rather, he uses a boost pedal to drive the hell outta it and to keep the trannies from burning out from being so badly overdriven his roadies have a number of fans blowing on the back of the amp!
> 
> Even then, he's lucky to get through a whole gig without frying at least the output transformer. For him, this is not a big deal. His techs replace it and the next gig they do the same thing again!
> 
> ...


Actually, Larry Cragg, Neil's longtime guitar/amp tech says that his main Deluxe has an output transformer from a brown Deluxe and that this was confirmed by Paul Patronette at Mercury Magnetics.


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## nonreverb (Sep 19, 2006)

The later Deluxe trannies are able to handle 6L6's. Not officially mind you but they can. My '74 Deluxe Rev. is living proof. I've been running 5881's in it for years.



ampaholic said:


> Actually, Larry Cragg, Neil's longtime guitar/amp tech says that his main Deluxe has an output transformer from a brown Deluxe and that this was confirmed by Paul Patronette at Mercury Magnetics.


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## marauder (Oct 19, 2009)

Well, the amp sounded good, but I still passed for now. The tweed covering was more like tweed pattern wallpaper, and not a neat job. Haven't heard back from a couple of amp techs I emailed for a price quote to give it a once over. Expressed my concerns to the owner, who understood, especially since there is no knowledge of the builder/original owner. Unless he wants to drop his value significantly, I think I'm out.


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