JCM DSL 50 with 6550 Power Tubes

[WaR HeaD]

Hi dudes...

my guitar teacher suggested me to try 6550 power tubes ala Zakk Wylde, John Norum (Europe) or Slayer, for more headroom, more "darkness" and more bass...

will i have to make a huge mod to the amp? asked a store about them and told me DSL 50 can´t support 6550 because every tube has already 50 watts of power, but i saw europe DVD and Norum uses a dsl 50 with 6550, that means that he (or marshall for him) has changed the whole power section to a 100 Watts or something?

thanks for the info, dudes

 

[Marcel]

Re: JCM DSL 50 with 6550 Power Tubes

I think that's wrong about the 50 Watts and give you bump...

 

[LesPaulRules]

Re: JCM DSL 50 with 6550 Power Tubes

A few resistors will have to be changed, and obviously the tubes will have to be re-biased.

The volume of the amp won't change (don't think the transformer is beefy enough to supply high enough plate voltage), but the sound will change. The low end will be much tighter.

 

[Lake Placid Blues]

Re: JCM DSL 50 with 6550 Power Tubes

With most of the drive and distortion being produced in the pre-amp in these amps, I don't see why 6550's wouldn't be a excellant power tube for metal. The clean channel will be cleaner and rounder too. Lot's of 50 watt Marshalls have run 6550's. You may want to have a tech check on the heater current draw on the modern power tranny though. As long as it can be biased, I don't see too much problem. A tech will probably have to change some resistors in the bias circut to make the conversion.

 

[WaR HeaD]

Re: JCM DSL 50 with 6550 Power Tubes

A few resistors will have to be changed, and obviously the tubes will have to be re-biased.

The volume of the amp won't change (don't think the transformer is beefy enough to supply high enough plate voltage), but the sound will change. The low end will be much tighter.

With most of the drive and distortion being produced in the pre-amp in these amps, I don't see why 6550's wouldn't be a excellant power tube for metal. The clean channel will be cleaner and rounder too. Lot's of 50 watt Marshalls have run 6550's. You may want to have a tech check on the heater current draw on the modern power tranny though. As long as it can be biased, I don't see too much problem. A tech will probably have to change some resistors in the bias circut to make the conversion.

...ok so i won´t need to change the transformer for a 100W one, right?

btw, how much would the rebiasing, etc etc...without the tubes?

thanks for the replies

 

[STRATDELUXER97]

Re: JCM DSL 50 with 6550 Power Tubes

...ok so i won´t need to change the transformer for a 100W one, right?

btw, how much would the rebiasing, etc etc...without the tubes?

thanks for the replies

You won't need to change out your transformer,but you will need a tech to tweak your bias supply to accept the 6550 tubes...

 

[34029324079]

Re: JCM DSL 50 with 6550 Power Tubes

a la wydde? that just may rip!

 

[WaR HeaD]

Re: JCM DSL 50 with 6550 Power Tubes

so...today, i´ve called marshall (the spanish dealer) for this change of tubes, and the tech has told me that he´ll have to put a new transformer, new bias, etc etc, and the price will be really expensive... he´s told me also that i should better sell the amp for a new one that could accept those tubes (the zakk wylde sig. p/e)...

anyway, thanks a lot for the replies

 

[Luke Duke]

Re: JCM DSL 50 with 6550 Power Tubes

so...today, i´ve called marshall (the spanish dealer) for this change of tubes, and the tech has told me that he´ll have to put a new transformer, new bias, etc etc, and the price will be really expensive... he´s told me also that i should better sell the amp for a new one that could accept those tubes (the zakk wylde sig. p/e)...

anyway, thanks a lot for the replies

A tube can supply up to X amount of power, so just because I have two 50 watt rated KT88 does not make my 50 watt JMP 100 watts. You should be able to have a few resistor values changed, and maybe the pot and be ready to go.

Sounds like your tech just wants to sell you a new amp. Not just a regular amp either, but a REALLY expensive amp. I'd avoid him like the plague if I were you. I'd drop Jeff Seal a PM if I were you and ask him about everything involved in putting in a different type of tube.

Luke

 

[MDS]

Re: JCM DSL 50 with 6550 Power Tubes

After you talk to another tech, let us know what you end up doing and how much it cost...I JUST picked up a broken DSL50 that I'm going to fix, and I might mod it along the way!

Mike

 

[Lake Placid Blues]

Re: JCM DSL 50 with 6550 Power Tubes

Is it the mains (power) transformer, or the output transformer, he says must be replaced? If it's the mains then he must think that the power transformer heater supply can't handle the current draw. The EL34 draws 1.4 amps and the 6550 draws 1.6 amps. If it's the output transformer, then it's just BS.

An alternative plan would be to use big bottle 6CA7 tubes (there are some decent re-issues now) instead of 6550's. The 6CA& is an American version of the EL34. The 6CA7 gives a response in-between the European EL34 and the 6550. These would just need to be re-biased with no other mods.

 

[Gearjoneser]

Re: JCM DSL 50 with 6550 Power Tubes

If I were you, I'd buy JJ E-34L's and GT12AX7C's. E-34L's are just like EL-34's, except they have 10% more output, a bigger low end, and all you have to do is pop them in and adjust the bias pot on the back of your amp a tiny bit.

E-34L's is what I put in my 50W Marshall Jubilee, and it sounds as fat as a 100W amp, and I didn't lose that EL-34 flavor. IMO 6550's are NOT the Marshall sound, and the only reason Zakk sounds good with them is because his whole rig is dialed in...in other ways like EMG's, different speakers, OD pedal etc. I'll put it this way...there have been more players that yank out the 6550's in favor of EL-34's than visa versa.

 

[J Moose]

Re: JCM DSL 50 with 6550 Power Tubes

I'm with GJ.

My JCM 800 has 6550's and while it sounds like a Marshall, it doesn't sound like a Marshall. I've got a bunch of Mullard EL34's here and as soon as I burn through the 6550's I'm going to have it swapped over to EL34's. I think the bottom end might be tighter with the 6550's but it's bigger & smoother with EL34's.

LPB - That's a good point about amperage...but the difference between 1.4 and 1.6 amps is nothing really. The amp might pull that while idling, but at full blast it'll swing up...maybe 2, 3 or 4 amps. I don't know, never mesured it. But I see it all the time in the mix room with the power amps & power conditoner in the amp rack. I'll can monitor at about 80-85dB SPL and draw "X" amps...but when I crank it up to 100-105dB SPL I'm drawing about 1 amp more.

In other words, that tech should be avoided!