Amp In The Shop - Output Tube Advice

[Jeff_H]

Ok, my Marshall is over at Splawn Guitars. They are going to give it the once over, and call me in a couple of days. I think that on top of whatever they find is causing the hiss, I may need some new output tubes. I am currently running Svetlana EL-34's. I am looking for a little tighter lows and slightly crisper highs than what I currently have, but like the overall vibe of the EL34's (but have to say that Two Rock out in Cali with the 6L6's sounded damn fine).

So give me some ideas, tubes you have experience with, ect. Here are what I think will work best:

Svetlana's (of course)
Siemens (NOS)
EH EL34's

I'm also curious about the new GT 6CA7's. Kind of a cross between a 6L6 and an EL34? What about a KT66?

Remember....tighter, crunchier lows and slightly crisper highs...but still with plenty of mids.

 

[theodie]

Re: Amp In The Shop - Output Tube Advice

EH EL34's!!! They did the same trick for me in my 2555SL!!!!!

 

[RGN]

Re: Amp In The Shop - Output Tube Advice

I'd have Scott switch the tubes to Sovtek KT88s!!

You ever tried those Splawn cabs Jeff? I may be ordering one soon. My buddy says great things but I have never checked one out.

 

[Jeff_H]

Re: Amp In The Shop - Output Tube Advice

I'd have Scott switch the tubes to Sovtek KT88s!!

You ever tried those Splawn cabs Jeff? I may be ordering one soon. My buddy says great things but I have never checked one out.

What type of tone do the KT88's have?

I have tried the cabs.....they are awsome. I am getting a 2x12 extension from him very soon. It will be black with the cane grill cloth. In fact, I am having the grillcloth on my combo redone while it is in there, so it will match. Here's what they look like.

 

[aleclee]

Re: Amp In The Shop - Output Tube Advice

Have you considered 6CA7s? IMO the EH ones are pretty cool.

 

[Jeff_H]

Re: Amp In The Shop - Output Tube Advice

Have you considered 6CA7s? IMO the EH ones are pretty cool.

Alec - I am really interested in those. I have been reading reviews on the EH and the Groove Tube version. Seems to be a nice cross between the EL34 and the 6L6....may be just what I'm looking for in terms of tighter lows and crisper highs, while still retaining the EL34 midrange sweetness.

I was hoping to hear from some who have tried the 6CA7's. Have you tried them?

 

[RGN]

Re: Amp In The Shop - Output Tube Advice

What type of tone do the KT88's have?

Scott is very well known for using KT88s in JCM800s. Basically, you'll just get
more volume, better clarity, and better sounding distortion. I have never heard of anyone being less than thrilled after switching to KT88s. Mention it to Scott and see what he says. I think he used KT88s in some of his Splawn Heads.

 

[aleclee]

Re: Amp In The Shop - Output Tube Advice

I was hoping to hear from some who have tried the 6CA7's. Have you tried them?

Yeah, I've run the EH ones in my Rivera Rake Reverb and Fuchs modded Traynor. I have the GT version in my non-reverb Rake. I've tried 'em both but I'll give you the caveat that I haven't actually A/B'ed 'em even though I've used 'em both in nearly identical amps. IME, the EH ones retain more EL34 "bark" than the GTs. The GTs are great, too, but IMO are probably not worth 3x the price of the EH ($75 vs $25). The GT's cleans are more 6L6'ish and the OD is less likely to buzz . . . but isn't going to crunch the same as EL34s.

For a point of reference, the EH EL34L is my benchmark EL34. It has the upper mid peak and breakup that says "Marshall crunch" to me. In comparison, the EH 6CA7 has deeper mids and a bit less sizzle. The 6CA7 will still crunch but not quite as aggressively due to the smaller upper mid peak. To some extent, you can probably make up some of the difference in the top end by turning up the presence so then you get better bottom end from the tubes and high end resonance from the presence.

IMO, FWIW, YMMV, etc.

 

[Jeff_H]

Re: Amp In The Shop - Output Tube Advice

Thanks Alec....that's what I was looking for on those. I would probably have gone with the GT's based on reputation, but if I go that route I will more than likely try the EH's now, especially considering the price difference. I don't mind paying the $75 bucks if they're what I'm looking for, but no sense wasting the money if it's not necessary. I converted my amp from 6550's because I did not like the harsh tone during breakup. I want to retain as much EL 34 sweetness as possible, while adding some tighter bottom end and top end crunch.

I may also ask Scott about the KT 88's. Thanks for that tip RGN. I know his amps with the KT's sound killer, I've played one in his amp room before.

 

[Gearjoneser]

Re: Amp In The Shop - Output Tube Advice

I know this is the extreme answer, but consider just selling the whole deal, and starting over with a Splawn Quick Rod and Cab! Sometimes, retubing isn't enough....it's just better to find an amp that excites you.

By the way Jeff, on Sunday night I finally got around to trying a Tungsol 12AX7 that Todd from Revolution.com gave me to try out. You won't believe it, but it made my Jubilee sound 1 notch better! That's a great 12AX7!

I still think you should just forget about changing the grillcloth and just cash out of that amp, before you drop any more money. Sell a few duds, and get a Bogner or Splawn. You're probably tired of the sound of it anyway, since you've had it a long time.

 

[Jeff_H]

Re: Amp In The Shop - Output Tube Advice

GJ....the amp I have is actually really close to what I'm looking for. I've got enough invested in it that I feel I need to see it all the way through. The cost of a new set of power tubes and $40 for the grillcloth are not very big expendatures in my book at this point, and the circuit Jeff designed for me is really nice. I'm just looking for a few little tweaks. Most people would plug into the amp and say...WOW. I do too, but the longer you have something (you know this) the more detailed your awareness becomes of it.

I'll go with some different tubes (possibly) in the output section, get the hiss fixed, and go from there. I'll monkey around with the GT-M and the GT-C, as well as picking up the Tungsol you recommended. If at that point I can't dial in the sound I want with the addition of an extension cab, then I'll look to something different. Puckboy has a Quick Rod for sale at a great price, but it's 100 watt, and I really need a 50 watt.

I can pick up a Shiva, a 50w Splawn or even a Silver Jubilee head all in about the same price range. If this does not pan out, I'll head in that direction. At this point I have about $850 total in my amp over the past 2 years (not including tubes which I deem as maintenance parts). I see combo's like mine in good shape going for close to a thousand on eBay, so I know I can get out of it if I need to.

 

[Gearjoneser]

Re: Amp In The Shop - Output Tube Advice

I think that simply hooking that combo up to a 2-12 or 4-12 will give you what you're looking for. To me, Marshalls just never sound quite right with an open back, but the circuit in your amp is fine. Personally, I think it'd look cool sitting on another cab, for a combostack.

 

[theodie]

Re: Amp In The Shop - Output Tube Advice

I know this is the extreme answer, but consider just selling the whole deal, and starting over with a Splawn Quick Rod and Cab! Sometimes, retubing isn't enough....it's just better to find an amp that excites you.

By the way Jeff, on Sunday night I finally got around to trying a Tungsol 12AX7 that Todd from Revolution.com gave me to try out. You won't believe it, but it made my Jubilee sound 1 notch better! That's a great 12AX7!

I still think you should just forget about changing the grillcloth and just cash out of that amp, before you drop any more money. Sell a few duds, and get a Bogner or Splawn. You're probably tired of the sound of it anyway, since you've had it a long time.

Jonesy, could you please explain more in depth about the Tungsol 12AX7's. What tubes were you using before also? How would they compare to EH 12AX7's, Sovtek LPS's and JJ's 12AX7's?

 

[Jeff Seal]

Re: Amp In The Shop - Output Tube Advice

I think that simply hooking that combo up to a 2-12 or 4-12 will give you what you're looking for. To me, Marshalls just never sound quite right with an open back, but the circuit in your amp is fine. Personally, I think it'd look cool sitting on another cab, for a combostack.

Jeff, I gotta agree with GJ here......I've got (many) 412's and one 212 (the big cab 212..same size as the 412) and there's a large enough difference between even these two that's quite noticable. You're amp is probably going to sound the best through a standard 412 @ 16 ohms.....
I can assure you that your amp most certainly shook some dust out of the drop ceiling at the shop when I ran it through my 412...(since I only had the chassis...)

I must confess I have never really been a huge fan of open back Marshall's either, although the original BB was an exception...

....anyway, on the subject of tubes....since I'm more of a "go with what hasn't failed yet" kinda guy...(fine line between being a "tech" that loves to "tinker", and a "working musician" who can't afford to have things fail at a gig....) I'm still pretty set on the Svetlana's, although the Siemen's seem to be pretty promising.....haven't done a side by side "scientific" evalutaion..(using the exact same amp and taking notes..)....maybe I'll add that to my "things to do" list, which in my case is based more on a "yearly" basis.....

no rest for the wicked!....

Let me know if I can be of any help...

Jeff Seal

 

[Jeff_H]

Re: Amp In The Shop - Output Tube Advice

Thanks Jeff.....a cab is my next purchase. I also think that will get me much closer to the tone I am looking for.

 

[Erlend_G]

Re: Amp In The Shop - Output Tube Advice

By the way, do anyone have opinions of EH El84's?

Thanks.

 

[Willis]

Re: Amp In The Shop - Output Tube Advice

Have you considered 6CA7s? IMO the EH ones are pretty cool.

Your description of them sounds exactly like what I want (except for buzzy OD...). I have EH EL34s in my Marshall right now, and my Peavey power amp I'm going to get soon has 6L6s. I'll probably switch to the EH 6CA7s when I get a few mods to it. Thanks for all the info!

 

[KLINKDETROIT]

Re: Amp In The Shop - Output Tube Advice

I just bought a quad of EH6CA7 & a quad of GT6CA7. tubes. I have the amp in the shop. When I get it back I will post a reveiw. I will be selling 2 sets of tubes after I am done comparing. I have a set of Svetlana EL34 tubes in my Mesa rectifier now that are about 1 month old(20 hrs). I will probably be selling these and 1 set of 6CA7 tubes. Not sure what brand I will be keping though.
About Mullard gt12ax7 tubes, I have tried them and the 12ax7c as well as 12ax7EH preamp tubes. I like the Mullard reissue in #1 and the fx loop and high gain EH preamps in 2 & 3 and a balanced (110/110) EH in the phase invertor. The Mullardgt sounds big and fat and articulate and makes the biggest difference but lacks distortion. That is why you need high gain tubes in other spots. I hear the Mullard gt is not good for a phase invertor but in the fx loop it really fattens things up when the loop is engaged.
I tried all Mullards and it was super fat but kinda dull and rounded lacking the bite off the 12ax7eh. The chinese 12ax7c was good but had the least output and was darker. Ok for a bright amp but I would definateley mix EH or Mullard reissues with it.