EL-34 vs. 6550 Power Tubes

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darwins_ghost

New member
What is the major tone difference between the EL34's and 6550 power tubes.
I was going to have my new Marshall retubed with a higher quality tube and I have no experience with 6550's.

I am not even sure if the DSL 100's can be re-biased for the 6550's. Any info?

Also, everywhere around here sells Sovtek and Groove Tube, which do you think gives the best tone? Or should I look into other tube brands off the net?

Thanks
 
Re: EL-34 vs. 6550 Power Tubes

You know, I have a 78 Marshall with 6550s. I also have an 81 Park with EL-34s (same amp).

Everybody and their mom advocates changing the old 6550 amps to EL-34s. I really love my Marshall- probably moreso than the Park. I don't know that the difference is in the output tubes the amp is running. Although everybody (and their mom) tries to convince me to convert my Marshall to 6550s, there's no way I'm going to mess with a good thing.

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Re: EL-34 vs. 6550 Power Tubes

All my knowledge is second hand but 6550's should remain cleaner at a higher volume than EL34's. I would also venture a guess that they have less of that EL34 bark. The American version is the KT-66, right? That's used for bass amps and tube hi-fis I believe.
 
Re: EL-34 vs. 6550 Power Tubes

6550s are harder and cleaner sounding, Zakk uses them. I don't know if your amp can be biased for them without some changes to the bias circuit though. Even the old Marshalls needed some components changed so a 6550 version could use EL34s and vice versa. I actually like the 6550 Marshalls too. Hendrix used them too, the can put out more power than a EL34.

A good tube to try is a 6CA7, it's like a harder version of an EL34 but biases the same. EVH used Sylvania 6CA7s in his old Marshalls. I have a set of EH 6CA7s in my Trace Speedtwin and really like them.

<$0.02

PFDarkside said:
All my knowledge is second hand but 6550's should remain cleaner at a higher volume than EL34's. I would also venture a guess that they have less of that EL34 bark. The American version is the KT-66, right? That's used for bass amps and tube hi-fis I believe.
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Yeah, they are "harder", it takes more to push them into overdrive. 6550s originally were American tubes, kind of a harder, stronger EL34 which was a British tube. The KT-66s are actually more of a 6L6 type tube. JJ makes a KT-77 also, which is an EL34 replacement but also harder, I haven't tried it, but from the description it is probably similar to a 6CA7.
 
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Re: EL-34 vs. 6550 Power Tubes

my experience with switching from 6l6 to 6550:

- amp got a little louder
- 6550's are really clear or have a flat eq. not as much character as other tubes
- 6550's pretty much wont distort. my clean channel before was a little dirty to get it to be the same volume as my lead channel. definitely not the case now.
- the fatness of the 6l6s seemed to cover up some of the distortion of my amp. the 6550s made the distortion channel seem like it had quite a bit more gain but because of their transparent sound, the amp seemed to get a little fizzy (this is with the gain turned down from the 6l6 settings)
- they do still have a 'bark' but it is different
 
Re: EL-34 vs. 6550 Power Tubes

6550s (and their direct replacements - KT88s) will distort. Trust me.

As opposed to EL34s: expect more headroom, deeper/tighter bass, extended highs, and a more flat EQ (like ksmith mentioned).

I have KT88s in my Splawn and have never considered a conversion.
 
Re: EL-34 vs. 6550 Power Tubes

sosomething said:
6550s (and their direct replacements - KT88s) will distort. Trust me.
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wow i dont even want to imagine how loud that is.:headbang:

i can get the preamp to add some distortion to the clean channel but even at band practice volume levels there is no distortion. my amp does have a fixed bias so i'm sure the tubes are running a little cold.
 
Re: EL-34 vs. 6550 Power Tubes

ksmith63 said:
wow i dont even want to imagine how loud that is.:headbang:

i can get the preamp to add some distortion to the clean channel but even at band practice volume levels there is no distortion. my amp does have a fixed bias so i'm sure the tubes are running a little cold.
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Mine's biased on the hot side, for one... for two, I'm running at half-power (around 60-75 watts), and three... I blows dat shiznit up, man. It's METAL. I crush it. :D

The kind of music my band plays only sounds good through a layer of ear blood.
 
Re: EL-34 vs. 6550 Power Tubes

Personally I prefer KT88s to 6550s. They sound a little softer, but have a huge low end thump with lots of top end sparkle like a 6550.

Above either I really dig the EL34s, they sound a bit smoother to my ears.

As Dave pointed out some amps sound better with one or the other. When you get to looking at amps every component has a tolerance usually +/-10%. If your tolerances stack up a certain way it will make your amp sound a little different, so some specific amps sounds good with one and other specific amps sound good with another.

Luke
 
Re: EL-34 vs. 6550 Power Tubes

darwins_ghost said:
can you post some pics from the front?

Thanks
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If I remember right, that head is the same box, but it has a 100w MV with 6550s in it.

I lost the impedance selector for the amp after playing this show.

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My "current" rig 14 years ago-

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Re: EL-34 vs. 6550 Power Tubes

The diff I hear is that the 6550's sound "bigger" and "cleaner" and less complex in the mids. The EL-34's have that classic Eric Clapton with Cream kinda honky smooth crunch and the 6550's don't do that EVH "Brown Sound" kinda tone as satisfyingly or naturally as the EL-34's do. Lew
 
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