Pull two of the EL84s out of a DC-3 to halve its Wattage?

[LEVEL4]

WARNING: ACCORDING TO MESA/BOOGIE, PETALUMA, TECHNICAL SUPPORT DOES NOT RECOMMEND PULLING TWO OF THE EL84s IN DC-3s. IT WILL CAUSE OVERHEATING OF THE REMAINING EL84s AND POTENTIALLY DAMAGE THE AMP.

I have a Peavey 6505 that I pulled two of the 6L6 power tubes out of to halve its Wattage. Jerry at FJAmods advised me on how to do it safely (pull either the inner two or outer two, change fuse to lower rating, set your impedence to half your actual impedence load). It worked like a charm, and I now have a lot more usable "play" on the post-gain volume pot.

Can you do the same with a DC-series Mesa/Boogie amp? This DC-3 is just the loudest f*cking 30-Watt amp I've ever heard. It's waaaaay too loud for my usage. I know it won't make a HUGE difference in output, but anything would help.

P.S. I also own a TubeCube attenuator, and I only just hooked it up to the DC-3. Works great! But, I would still like to know if you can pull the tubes.

 

[Ken j]

Yes.

 

[LEVEL4]

Thanks. Is it the same deal, then? Pull EITHER the inner two OR the outer two EL84s?

 

[sixtonoize]

I'd wait for a few more responses.

In octal amps (like El34s, 6L6s, etc) pulling tubes won't hurt anything. However, noval tubes (EL84s) sometimes have different setups, which can cause amp damage when you pull tubes. I know that this is the case with the Peavey Classic series.

I can't honestly tell you if it's safe or not, but the fact is that running 1/2 the wattage won't make a drastic difference in sound. It will make a barely noticeable difference, and you'll mostly lose bass response, not so much volume. 15 tube watts is still pretty **** loud.

 

[DougM_TX]

I ran mine with a pair pulled for a while and gotta say that I agree with sixtonoize...just didn't like the results.

Got alot more satisfaction by do the mod to remove the 220K resistor on the Output Level pot. Made the output level control much better.

 

[LEVEL4]

In octal amps (like El34s, 6L6s, etc) pulling tubes won't hurt anything. However, noval tubes (EL84s) sometimes have different setups, which can cause amp damage when you pull tubes. I know that this is the case with the Peavey Classic series.

I can't honestly tell you if it's safe or not, but the fact is that running 1/2 the wattage won't make a drastic difference in sound. It will make a barely noticeable difference, and you'll mostly lose bass response, not so much volume. 15 tube watts is still pretty **** loud.

Thanks for your reply! Yeah, good to know. Tried to call Mesa/Boogie today, but they're closed on Fridays! Guess I'll have to wait until Monday. At least my attenuator sounds pretty good on this amp. Oh well. Pulling two of my 6L6s sure worked great on my 6505. The difference is definitely noticable, and it didn't affect the 6505's tone at all. In fact, it never sounded better.

Got alot more satisfaction by do the mod to remove the 220K resistor on the Output Level pot. Made the output level control much better.

Hey, fellow DC-3 guy! By the way, which two tubes did you pull? The outer two or the inner two? It is either the inner or the outer on the DC-3, right?

What did clipping the resistor actually do, tone-wise, or output-wise? Oh, duh. It just makes the pot's range a little more in line with the amp's output, yes? Generally, where is the 220K resistor located? Can I get to it without pulling the chassis? Duh! I guess it's near the output pot, yes? Once you clip the resistor, do you also have to solder a jumper in to close the circuit again? Are there any other DC-3 specific mods you know of worth doing? Thanks for any help on this.

 

[Calamity]

In octal amps (like El34s, 6L6s, etc) pulling tubes won't hurt anything. However, noval tubes (EL84s) sometimes have different setups, which can cause amp damage when you pull tubes. I know that this is the case with the Peavey Classic series.

I can't honestly tell you if it's safe or not, but the fact is that running 1/2 the wattage won't make a drastic difference in sound. It will make a barely noticeable difference, and you'll mostly lose bass response, not so much volume. 15 tube watts is still pretty **** loud.

Thanks for your reply! Yeah, good to know. Tried to call Mesa/Boogie today, but they're closed on Fridays! Guess I'll have to wait until Monday. At least my attenuator sounds pretty good on this amp. Oh well. Pulling two of my 6L6s sure worked great on my 6505. The difference is definitely noticable, and it didn't affect the 6505's tone at all. In fact, it never sounded better.

Got alot more satisfaction by do the mod to remove the 220K resistor on the Output Level pot. Made the output level control much better.

Hey, fellow DC-3 guy! By the way, which two tubes did you pull? The outer two or the inner two? It is either the inner or the outer on the DC-3, right?

What did clipping the resistor actually do, tone-wise, or output-wise? Oh, duh. It just makes the pot's range a little more in line with the amp's output, yes? Generally, where is the 220K resistor located? Can I get to it without pulling the chassis? Duh! I guess it's near the output pot, yes? Once you clip the resistor, do you also have to solder a jumper in to close the circuit again? Are there any other DC-3 specific mods you know of worth doing? Thanks for any help on this.

http://forum.grailtone.com/viewtopic.php?t=12627&highlight=dc3+mod

Original: http://www.thegearpage.net/board/showthread.php?t=229027

Basically, you know how the output knob works on the DC-3 currently:

1-2 requires superhuman hearing
2.00001 = Monstrous volume jump
3 = Max
3+ = ???

By clipping the resistor, you smooth out the taper of the pot, and it actually works like a volume pot, i.e. it increases in volume smoothly, and hell, it sounds great even at bedroom levels. At my house I never run my DC-3 over Master 2 and Output 2, if I do, it shakes the floorboards :lol:

Depending on which version of the DC-3 you have, the location of the resistor can vary a tiny bit. However, you will definitely need to pull the chassis. The old DC-3's have the resistor right at the end of the output wires, while the newer DC-3's have the resistor a little bit farther away (it's still obvious--it's the only one near the output pot). I didn't have a desoldering iron but I was desperate to get it done so I just snipped it. Didn't cause any problems, but the best thing to do would be to desolder it and keep it in a plastic bag or something (just in case, y'know)., but that's all you need to do.

Monsta-Tone did some mods to his DC-3, namely the Cathode Bias/Fixed Bias switch. I think he put something else on, but I don't remember. I'm sure he'll chime in eventually: he's a helpful guy

Hope that helps!

 

[LEVEL4]

Basically, you know how the output knob works on the DC-3 currently:

1-2 requires superhuman hearing
2.00001 = Monstrous volume jump
3 = Max
3+ = ???

Hey, thanks for all that info! Really appreciate it! Yeah, I only JUST found that out tonight while playing with my attenuator about the output volume pot thing. At night I can only play it at <'1'. At '2' it's loud as f*ck. Then it just seems to top out at 3+. Who knew?

By the way, it looks like a ***** to pull the chassis to clip that resistor. I assume you have to pull all four screws. How do you reach the rear screws? Also, you don't have to solder a jumper to it after you clip it, right? It's already in parallel to the pot, right? Thanks again!

 

[Monsta-Tone]

Got alot more satisfaction by do the mod to remove the 220K resistor on the Output Level pot. Made the output level control much better.

This is a great mod. It really makes the Output knob useable on all of the DC amps that I've tried it on.


Other mods:
Cathode/Fixed Bias switch
Better Preamp tubes
Mark IV fan in the back of the amp
Remove the Vintage 30 and use a Heritage 30 (or, in my case, a Mojotone BV30H clone). This was the best mod I ever did to mine.

 

[Calamity]

Basically, you know how the output knob works on the DC-3 currently:

1-2 requires superhuman hearing
2.00001 = Monstrous volume jump
3 = Max
3+ = ???

Hey, thanks for all that info! Really appreciate it! Yeah, I only JUST found that out tonight while playing with my attenuator about the output volume pot thing. At night I can only play it at <'1'. At '2' it's loud as f*ck. Then it just seems to top out at 3+. Who knew?

By the way, it looks like a ***** to pull the chassis to clip that resistor. I assume you have to pull all four screws. How do you reach the rear screws? Also, you don't have to solder a jumper to it after you clip it, right? It's already in parallel to the pot, right? Thanks again!

Aye, you can just snip it and yer done. On mine, I just have the four mounting screws on the top, and 2 reverb wires on the bottom left. Not sure about yours as some have a center bolt through the back--that needs to go, too.

 

[DougM_TX]

Yea, I just snipped mine out as well. Didn't want to put the heat to the board (if I didn't have to) and resistors are easy to come by if I ever wanted to put it back (which I won't 'cause I'll NEVER sell this amp so there will be no reason to put it back to stock).

LEVEL4 : If you need, I'll pull chassis and take a pic for you of where where it was. This is a later model DC-3. Bought it new late '97.

 

[LEVEL4]

Yea, I just snipped mine out as well. Didn't want to put the heat to the board (if I didn't have to) and resistors are easy to come by if I ever wanted to put it back (which I won't 'cause I'll NEVER sell this amp so there will be no reason to put it back to stock).

LEVEL4 : If you need, I'll pull chassis and take a pic for you of where where it was. This is a later model DC-3. Bought it new late '97.

Good point (about the heat)! Thanks! Don't trouble yourself! If I get lost in there, I'll hollar back at ya. But, do you have any tips on pulling the chassis?

 

[LEVEL4]

I ran mine with a pair pulled for a while and gotta say that I agree with sixtonoize...just didn't like the results.

So, your other two EL84s didn't start smoking, your amp didn't catch on fire, your fuses didn't blow, and your output transformer didn't short out. So it's okay to pull 'em, then, right? What exactly didn't you like about it? Did you notice a change in anything other than output volume? Like I said, I pulled two 6L6s outta my 6505 and it now sounds GREAT. Or, at least, it sounds the same as it always did, but with a LOT more play on the post-gain pot. Very noticable difference, and TOTALLY worth doing, IMO.

 

[LEVEL4]

Well I did it. Turned the amp on and nothing blew up (yet!).

• Pulled the two outside EL84s.
• Used the 4Ω output to my 8Ω cabinet.
• Still need to replace fuse with lower value.

I noticed no obvious change in tone. I noticed no reduction in bass response. I can't crank it yet 'cause it's really late, but the output pot definitely goes higher with less volume. Hopefully, more EL84 saturation is in order tomorrow, without using a tone-stealing attenuator. It's still gonna be the loudest damned 15-Watt amp on the planet, though, I'm sure.

 

[DougM_TX]

First of all pull the chassis was easy - mine is a combo. I just backed the 4 top mounting screws out a little at a time so I didn't end up with one supporting all the weight. Just took a pic so I could get the reverb cables back in the right place. Sliding it back a bit then and it sits on the side braces in the cab. If I recall then needed to lift if just a bit to slide it out over the braces.

As far as running with 2 tubes pulled...I rarely take this amp out of my home office any more (just play for my own enjoyment these days) and was looking (of course) for the ability to drive the output tubes harder with lower volume. It was just still too loud for what I was trying to accomplish. This was before I did the vol control mod so it might be worth trying it again sometime. Of course it's all pretty subjective and my tastes rotated a bit over the last few months from metallica and ozzie back to the beatles and I'm loving this amp just as it is...so who knows LOL.

 

[LEVEL4]

WARNING: ACCORDING TO MESA/BOOGIE, PETALUMA, TECHNICAL SUPPORT DOES NOT RECOMMEND PULLING TWO OF THE EL84s IN DC-3s. IT WILL CAUSE OVERHEATING OF THE REMAINING EL84s AND POTENTIALLY DAMAGE THE AMP.

 

[Monsta-Tone]

Well....sheeeeesshh!!

There you have it. Last thing you want in a DC-3 is more heat.

 

[DougM_TX]

hehe, i guess thats good to know.

Glad I didn't fall further in love with it with a pair pulled.

 

[LEVEL4]

Yeah, well, I was just wondering. I mean, I questioned the tech pretty hard. I was trying to determine if Mesa was just "protecting" the "integrity" of the design, offering "official company policy" regarding amp modifications, or if the mod really does damage the amp. Too bad, because to me, the amp sounded better with two of its tubes pulled.

I kept asking him for specifics. All he kept saying was that the remaining tubes would heat up too much. Why would that be the case? I then tried to determine if I was just going to go through tubes faster, or if this practice would actually damage the output transformer or the amp's other components. Don't really remember if I ever got an answer to that question. He kept saying, "the amp's not designed for that."

But, I guess I agree with him, since he did admit that it's not like a 6L6 amp, where it's totally okay to pull two of the tubes. Then I asked him if it's because EL34s/6L6s are octal designs as opposed to noval EL84s, as sixtonoize mentioned here previously, but don't remember the reply.