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Thread: Anyone use an EH 6CA7?

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    Toneologist ACH91332's Avatar
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    Default Anyone use an EH 6CA7?

    Anyone ever use the Electro-Harmonix 6CA7? No not the EL34 the 6CA7 they make. I like my JJ E34Ls I have in my Marshall right now but that's only because they have a tight bottom end. They don't sound too musical to my ears. I read someone saying the EH 6CA7 had a sweet high end, buttery mids, and a very powerful, tight, and punchy bottom end.

    Anyone ever use them? I'd like to hear what some people think. The whole idea of an EL34 with a more ballsy and powerful tone is very appealing to me. Please don't recommend the KT77. I've used them and the bottom end is all flubby and it lacked mids. I didn't care for it at all.

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    Ultimate Tone Member JB6464's Avatar
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    Default Re: Anyone use an EH 6CA7?

    I have used those in my 1959 Marshall's. They are very nice tubes if you get them matched from a good dealer. My favorate Marshall tube is the Fat-Bottled 6CA7 Sylvania.
    The EH 6CA7 is close to the GE 6CA7 NOS version and is a true Beam Tetrode design like the original's. The EH 6CA7 has a slightly mid-scooped sound like a
    6L6 but still has the EL34 compression. Kind of like having the best of both tubes in one but with more output and warmth. The low end will be tight and the top end will still cut through the mix giving you a very musical warm vintage tone.
    There is no mods needed, just plug them in and check your bias. i like to run them around 70-75% max dessipation. I found that the Fat-Bottled 6CA7 tubes like a hotter bias to get warm smooth vintage tones.
    My 2 cents worth.

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    Alnico 6/8 gibson175's Avatar
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    Default Re: Anyone use an EH 6CA7?

    YEP! Put them in my musicman. They definitely give more bottom end than any EL34's. They also run a bit cleaner too if you are after more headroom. I like them.
    ps - i have JJ el34's in my marshall too.
    You may not notice a huge change (from jj el34's which have plenty of bass) due to the fact that some more modern marshalls trim out a lot of the bass in the eq, but you will notice a difference in an older/cleaner type marshall.
    Last edited by gibson175; 02-23-2010 at 07:21 PM.

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    Toneologist ACH91332's Avatar
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    Default Re: Anyone use an EH 6CA7?

    Yeah I mean I liked the KT77 even though it lacked some mids but the bottom end was just flubby and loose. It just didn't have any tightness or punch in my JVM. The EH 6CA7 sounds like it might work for me to tighten and clean it up a bit while having the EL34 compression and vibe.

    Anyone else care to share before I commit to this?

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    Ultimate Tone Slacker Lake Placid Blues's Avatar
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    Default Re: Anyone use an EH 6CA7?

    I'm thinking about trying them in one of my Jubilees. That particular one is 2554 1x12 combo. What I like is the potentially stronger bass for that amp. Plus the clean channel from a tube that is bit like a 6L6 run clean.

    The EH ones are about the only practical choice left for fatboy 6CA7 tubes. Slightly used examples of the Sylvania/GE (they are identical to each other) are asking almost $180 per tube, and NOS examples seem to be about right there with the GEC KT-66 in price now. I couldn't find any ANOS or NOS Sylvania/Ge tubes. All sold out. I think its a better alternative to 6550's for an EL34 amp. The 6550 adds bottom but it's also a very different tone from EL34. Many of us want to keep most of the EL34 vibe and feel.

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    Ultimate Tone Slacker Lake Placid Blues's Avatar
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    Default Re: Anyone use an EH 6CA7?

    I understand that Groove Tubes attempt to produce a decent re-issue of the fat boy 6CA7 was a debacle. Too bad.

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    Default Re: Anyone use an EH 6CA7?

    I like 6CA7's...very nice alternative to EL34. I remember reading somewhere that the GT version had a high failure rate. Since they last a long time if biased correctly, I think my 3 or 4 pairs of Sylvania's should see me out of this world...

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    Ultimate Tone Slacker Lake Placid Blues's Avatar
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    Default Re: Anyone use an EH 6CA7?

    ES350, what do you consider the max plate dissapation to be on the NOS 6CA7? 25 watts like an EL34 or more like 30 watts?

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    Default Re: Anyone use an EH 6CA7?

    The Amperex data sheets on Kbapps sites say max diss of 25 watts. With higher voltages like Marshalls, a pair will prolly put out closer to 60 watts. The Music Man amps ran them in another operating class (700 vdc for the 2275/2475 models) and advertised 150 watts from a quartet...maybe Glassman can chime in about here; he's the real amp tech.
    Last edited by ES350; 02-24-2010 at 04:49 PM.

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    Major General GAS aleclee's Avatar
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    Default Re: Anyone use an EH 6CA7?

    My favorite EL34 variant. Great tubes that don't need to be biased hot to sound great (giving you longer tube life to boot).

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    Electron Herder glassman's Avatar
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    Default Re: Anyone use an EH 6CA7?

    Quote Originally Posted by ES350 View Post
    The Amperex data sheets on Kbapps sites say max diss of 25 watts. With higher voltages like Marshalls, a pair will prolly put out closer to 60 watts. The Music Man amps ran them in another operating class (700 vdc for the 2275/2475 models) and advertised 150 watts from a quartet...maybe Glassman can chime in about here; he's the real amp tech.
    I actually haven't checked out the new EH 6CA7 yet but if it is anything like the EI 6CA7, I think I would set it up based on the assumption that its plate watt capability is somewhat less than 25 watts...I would base my figures on 22 watts and go from there. The bottom end should fill out nicely in comparison to an EL34.
    Now operating part time: Glassman Tube Amps...repairs, rebuilds, restorations & modifications of tube equipment.

    Still building: GlassMan Amplifiers (25 watt, all tube, single channel w/reverb, single 12" combo) and some more designs in the works.

    Located in Fort Wayne, IN


    Note: I've "parked" my website in case anyone has been looking for it. I moved locations and haven't updated the site to reflect this.

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    Major General GAS aleclee's Avatar
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    Default Re: Anyone use an EH 6CA7?

    Quote Originally Posted by glassman View Post
    The bottom end should fill out nicely in comparison to an EL34.
    It does. I've A/B'ed it with the JJ EL34 in my Rivera.

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    Default Re: Anyone use an EH 6CA7?

    So I don't have to worry about the flubby bottom end I had with the KT77 right? The JJ E34Ls had a fine bottom end and did what I wanted to. I just don't like the hit or miss reliability I get with their power tubes and I can stand to get something a little less aggressive. I use the JJ E34Ls not the EL34s but I guess they sound similar from what I've heard.

    I use EH tubes in my preamp now as they give me the warmth I liked with the JJ's but have way better definition to them and I like them enough to consider EH in my power section. Just to comment on the EH 12AX7 for a second, I'm so glad I had those laying around. The JJs seemed too round on top and I remembered the EH 12AX7 sounding similar man those things sound so amazing for their price. The JJs made sense that they were cheap. They didn't suck but it made sense however I don't know why the EH 12AX7s are so cheap. They are very nice.

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    Ultimate Tone Slacker Lake Placid Blues's Avatar
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    Default Re: Anyone use an EH 6CA7?

    Quote Originally Posted by glassman View Post
    I actually haven't checked out the new EH 6CA7 yet but if it is anything like the EI 6CA7, I think I would set it up based on the assumption that its plate watt capability is somewhat less than 25 watts...I would base my figures on 22 watts and go from there. The bottom end should fill out nicely in comparison to an EL34.
    What about the original Sylvania/GE big bottle 6CA7's? I have a tube data sheet for 6CA7/EL34 that has 25 watts for the plates plus 8 watts for the screens listed. European EL34s such as Mullards were often sold as 6CA7's in the US too.

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    Electron Herder glassman's Avatar
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    Default Re: Anyone use an EH 6CA7?

    Quote Originally Posted by Lake Placid Blues View Post
    What about the original Sylvania/GE big bottle 6CA7's? I have a tube data sheet for 6CA7/EL34 that has 25 watts for the plates plus 8 watts for the screens listed. European EL34s such as Mullards were often sold as 6CA7's in the US too.
    The total power output of a tube is dictated by the plate watt rating. The screen (also known as the accelerator grid) watt rating is based on the dissipation capabilities of the screen, but, the screen conducts toward the plate. At idle the screen current is negligable and anode current roughly equals cathode current. as the tube begins to operate, the screen adds its current to the mix and plate current roughly equals cathoode current + screen current. The screen resistor controls the amount of current the screen can dissipate; too much current and you lose the grid (or the resistor) and the tube either shorts or its output drops down to almost nothing.

    Think of the screen like a turbo charger inside your power tube.
    Now operating part time: Glassman Tube Amps...repairs, rebuilds, restorations & modifications of tube equipment.

    Still building: GlassMan Amplifiers (25 watt, all tube, single channel w/reverb, single 12" combo) and some more designs in the works.

    Located in Fort Wayne, IN


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    Default Re: Anyone use an EH 6CA7?

    Thanks. I'm going to play it safe. It looks like this set of 6CA7's isn't going to bias in at a safe setting in this particular amp with out mods to the bias circuit, which I don't want to do. Too bad because they sound great in this amp! Just as good or better as with Siemens EL34s. Even with a hot, hot, bias, the bottom end wasn't too flubby. Of course what I may consider a tight enough bass may not cut it for somebody else. But considering a mildier bias they should get a tight bottom biased up for it. I threw em in my JTM45 just for comparision sake and the bottom end still held together.

    These tubes sound very much EL34ish. Fatter for sure, but still EL34. They don't sound too much like a 6L6 or 6550 IMO.

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    Toneologist ACH91332's Avatar
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    Default Re: Anyone use an EH 6CA7?

    GOOD

    haha sounds awesome I will definitely have to give them a shot. The JJs are holding up fine for the moment being so when I have the money just laying around I'll make the move. It's nice to get the facts straight first.

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    Junior Member Clapton is God's Avatar
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    Default Re: Anyone use an EH 6CA7?

    Good info, guys. My Traynor Bass Master needs new tubes and I think I'll go with the EH's.
    Last edited by Clapton is God; 06-26-2010 at 10:02 AM. Reason: spelling

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