EL34 vs. 6L6GC vs. KT77 vs. 6CA7

Discussion in 'Amplifiers' started by Dusty Chalk, Nov 1, 2015.

  1. Dusty Chalk

    Dusty Chalk alberngruppenführer

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    I want to tuberoll. :iamconfused:

    I am familiar with tube-rolling from high-fi tube amps, but my understanding with PRS guitar amps is that in order to swap something else in, one has to bias it to 30 (mV?), correct? So if one tube is working at 75% of its capacity (when biased at 30) and another is working at 90%, is it correct that the first one will give me more headroom (I.E. I can turn up the gain higher before I get distortion)? Or is that all in the preamp tubes?

    I'm more of an EL84 guy, I should probably just get a Vox (or a Vox clone), neh? None of these will "sound" like an EL84, will they?
     
  2. AP515

    AP515 Mostly Normal

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    I really can't answer the details of your question any more than you already know, but it does give me the opportunity to derail the thread by saying that if you already have EL84 amps that you know you like, why not let this one be what you don't have?

    I started out a 6L6 (Fender) guy and have Fender and Mesa amps I love. But I got a PRS amp that sound totally different (El34's) and I like the change. My ears have adapted to the brighter sounds as well. I still love my 6L6's but this gives me more tonal options.

    Now back to the biasing question that I can't answer...
     
  3. Dusty Chalk

    Dusty Chalk alberngruppenführer

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    ...or am going to get. Yeah, no worries, that's in the cards, it's just that I have enough amps for my small apartment, so do not plan on getting a Vox/clone until I move.

    But your point still stands and is well taken -- I do also have an MDT, which is also of the EL34/6L6GC/KT77/6CA7 family of tubes, and I already like its sound, so instead of trying to make the Archon sound like the MDT, I should make sure it has a different flavor (and it does), but the goal of the tuberolling shouldn't be to make it sound like the MDT, so just thought "bright and sparkly". Or maybe I should go ultralinear (which it already sounds like to me, at least, the way I dial it in).

    Good advice, keep it coming.
     
  4. LSchefman

    LSchefman Hears Tones

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    I'm thinking that the interaction of the preamp section with the power section is going to vary from amp to amp, so it's really difficult to answer your first question.

    As an example, my 6L6WGB-equipped Two-Rock Onyx Sig sounded much more Marshall than Fender, but had its own identity. The DG30 has EL84Ms, and sounds nothing like a Vox. Nor does my Roccaforte Rockie 30, also EL84, that sounds far more Marshall than Vox. My EL84 Bogner Metropolis was way closer to Fender!

    As to whether to get a Vox or a Vox style amp, remember too that some EL84 amps don't sound anything like Vox amps due to the factors cited above.

    Heck, one of the better Marshall soundalikes out there used 6V6s instead of EL34s, and I had a Bad Cat Hot Cat a while back with EL34s that sounded way closer to Vox than Marshall. So I think it's much more likely that the whole circuit, and not just the power tubes, should be taken into consideration.

    Until PRS comes out with a Vox style amp (I hope they do one day!), I'd get a JMI Vox clone. It's like the real-deal old Vox amps, you don't find them everywhere, but if you Google this amp, you'll hear a 60s Vox circuit, and the thing even looks the business, down to the wiring and the transformers. Or there's always Matchless/Bad Cat for a different take on the Vox circuit. For me, the JMI is perfect enough that I'd go for that. An old Vox is a cool idea, and they're out there, some nicely restored, but I'm into reliability and would feel better with the newer one.

    http://www.lavintagegear.com/jmiamps.htm
     
    #4 LSchefman, Nov 1, 2015
    Last edited: Nov 1, 2015
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  5. Dusty Chalk

    Dusty Chalk alberngruppenführer

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    Thanks for the information. I was only familiar with the Dr. Z Vox clones, so you've added a couple others for me to investigate.

    You are of course, correct about circuits, not tubes defining flavour more than anything. I guess I need to really sit down and think about what sort of sound I want out of the Archon, as it seems pretty versatile.
     
  6. LSchefman

    LSchefman Hears Tones

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    The Matchless amps were originally designed in the 90s by Mark Sampson, who also designed the sister amps, the Bad Cats. They were originally made for rock stars and studios whose old AC30s/15s were on their last legs, or too valuable to tour. The ones that are like the Vox amps use an EF86 preamp tube like the AC30s. They're wonderful sounding amps. They've very highly regarded. The first one I saw was at Wisseloord, Polygram's studio in Holland, in the 90s. It really stood out because it was the first amp designed with "that look" that so many amp companies have since adopted. They aren't clones of an AC30, however, they have that vibe nailed and do more. They're a lot closer to the Vox tone than, say, the Dr. Z MAZ series that to my ear are really original designs with a Vox influence.

    The JMI amps are named after the original Vox manufacturer, JMI. They must have bought the rights to the name. The amps are clones of the AC30/15, and they do sound like old Voxes. If memory serves, they're made in England.

    And of course, true to my sadly picky tastes, none are what you might call inexpensive. ;)

    One last thing is that folks tend to underestimate the role that the old Celestion silver (and blue) speakers in the combo cabs played in the tone of those amps...
     
    #6 LSchefman, Nov 2, 2015
    Last edited: Nov 2, 2015
  7. vchizzle

    vchizzle Birdman.

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    Potentially and in theory, yes. In an amp like the Archon though, you'll likely get more noticeable results in the v1 preamp tube. Could try a 12at7 if you want more headroom. The Archon is designed for high gain via the preamp. I'm also pretty sure they tried to minimize the difference in feel and tone in the master volume. That's one of the reasons this amp sounds really good at low volumes. The clean channel is difficult to get to break up much, even with it's gain all the way up. Designed to stay very clean.

    EL34 will give you the most present midrange of all of those tubes in most cases. KT77 seem to have a low mid emphasis, 6ca7 usually closer to 6L6. This is my limited experience(though none of that is in the Archon). I have a set of EL34BSTR for my Archon, but have yet to try them. I'd say try a set of EL34 that are rated for earlier breakup to get more Voxy. Still...this amp is kinda designed opposite of Voxy tone though.
     
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  8. Kred

    Kred Thankful today

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    From designing and playing my own amps, I think the power tubes have a secondary effect on tone, mostly when they saturate and distort at high volume. At low volume, the power tubes don't affect tone much. Some of what you hear at high volume is output transformer saturation and speaker distortion.

    The primary effect on tone comes from the preamp tone stack, inter-stage coupling networks, and overall gain distribution. Changing preamp tubes is a good way to adjust the gain distribution. Lower gain preamp tubes are generally cleaner with more headroom.

    By adjusting a few tone stack components, you can change from mid-boost (like Marshall) to mid-scoop (like Fender or Mesa) making the amp sound totally different. You can explore more by downloading the free tone stack calculator from Duncan Amplification.

    One way to change the clean tone is to adjust the feedback from the speaker to the power amp phase inverter. More negative feedback gives a cleaner tone (like a Fender silverface), less negative feedback gives a more distorted tone (like a Fender tweed). Moving the feedback tap from the 8 ohm to 4 ohm speaker output halves the feedback, increasing the distortion.
     
  9. Dusty Chalk

    Dusty Chalk alberngruppenführer

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    Thanks for the continued information. I remember using TDSL for my tubes about 10 years ago. I'm not sure I have the balls to change components in my Archon, but I'm not sure I don't, neither. I'll start by tuberolling the preamp tubes.
     
  10. G-Man

    G-Man New Member

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    Learned a lot from this thread. I'm a huge Steven Wilson - Porcupine Tree fan and was trying to identify the amp sound. Bad Cat and PRS 22 and would have never guessed old Vox. I was sure it was some type of HiWatt clone.
     
  11. jc986

    jc986 Singlecut through Archon

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    I tried some EH 6CA7's in my Archon and noticed quite a difference. There was a lot more bass, a larger focus on the midrange, and rounder highs. It shifted the amp to more of a hot-rodded Marshally sound. I think I'm going to switch back to the 6L6's though because I prefer the tighter low-end and more modern sound they generate.
     
  12. Ben

    Ben New Member

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    TAD EL34BSTR's will also give you more bass.

    I've had Groove Tube EL34M's in my Archon for a while. After trying a few different types, I thought they had the best high gain tone.

    I also ordered some Tung Sol El34's. Can't wait to give them a try....
     
  13. Rider1260

    Rider1260 New Member

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    I've been a 6L6 ( Mesa ) guy forever but lately after dipping my toe in the Marshall pond with BrianC I am running 2 amps know mainly as 6L6 amps with EL34s
    My Mesa MKV had Mesa El34s and my PRS H has J+J EL34s.
    After trying EL34s in the MKV , I found it to be more old Mesa sounding which is what I wanted when I got it
    My H had EL34s when I got it and never found a need to change yet.
     
  14. vchizzle

    vchizzle Birdman.

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    I did some testing awhile back between Tung Sol 6L6GC, Chinese EL34BSTR and JJ E34L. All sounded good. I came away liking the JJ E34L best. They retained a solid, tight low end with more midrange that cut through the mix a little better. I actually expected to like the JJ’s the least figuring they’d accentuate what the Archon already had a lot of(low end and low mids). Just goes to show what happens when I start thinking and making assumptions.
     
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  15. LSchefman

    LSchefman Hears Tones

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    JJ actually makes some nice tubes. On another EL34 front, I’ve mentioned in the HXDA threads that I’ve been using NOS Siemens EL34s, late 70s or early 80s production that were probably made by RFT. As I understand it, the RFT tubes were of a quality level for Siemens medical equipment; in any case, they sound great, tighter and with a more solid midrange than the JJs, and a little more high end that isn’t harsh.

    They’re not very hard to find, and aren’t horribly expensive like the old Mullard or other premium brands.
     
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