Retubing my MK IV

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Hi all,

I've been doing some lurking here, and have found some useful tips and info. I particularly like the idea of trying one tube at a time in the V-1 slot, trying different things, then moving on to the other slots. I'm in the mood to try some different combinations, and willing to replace every tube in there, if need be. Power tubes are fine, and my focus right now is the pre-amp tubes.

My V-1 tube (an NOS RCA) finally crapped out, after many long years of service. I was in a pinch, and threw a JJ in there to get through a gig. Right now there's a combination of JJ's and Fender's. Now I need something better, as the JJ sounds fairly terrible by comparison to the RCA I had. I don't know what the RCA was, other than a 1960's model. I dropped the thing and it shattered, so I'll never know.

My question is, what tubes would you recommend I try. I'm thinking of getting a few kinds and slowly trying them out and working them into the chain. Say, 3 or 4 kinds that I could use as a starting point. Thinking of Mullards and Telefunken, Amperex etc...

I like heavier sounds, pretty aggressive in R-2, and saturated lead tones. I rarely play clean, but like it warm when I do. No effects in front, delay in the loop.

Thoughts? I thank you in advance...

Lawrence

 

[Timbre Wolf]

I like heavier sounds, pretty aggressive in R-2, and saturated lead tones. I rarely play clean, but like it warm when I do.

This description sounds like you'd appreciate the RFT ECC83 (12AX7 from East Germany). I'd say start with that one.

Now the RCA you lost, no matter which version, was not like the RFT. It would have been cleaner, both in the overdrive sense, and in the harmonic overtone content sense. And it would be brighter than the RFT.

I recommend you start with the RFT, and move along from there, if you feel compelled. State what qualities you'd like to enhance (tonal emphasis, more/less compression, clarity, overdrive, frequency extension, etc.), and I'll make a few more suggestions.

- Thom

 

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Cool, I'll get one and try it out. I've already got a couple of Amperex Holland ecc83's on the way, so that'll give me a couple of things to try for now. Less clean is okay by me. Harmonic overtones are desirable, as are articulate leads. Fairly saturated, but not to death metal standards. Thinking more in terms of a saturated rock tone than metal for the lead channel. For R-2, I would like plenty of crunch, but something that warms up if you lighten your touch or roll back the guitar volume knob. Can't say I really want any compression, unless it's fairly subtle.

I may wind up approaching the whole thing differently, by using the lead channel as a 3rd rhythm channel and use a boost or the GEQ for solo's. I guess it depends on where this tube adventure takes me.

I play a Parker Fly, One Classic and one Deluxe. They both have pickups that are Hybrid Gen 1 and 2 DiMarzio's, and have ceramic magnets. Not stock items, and they are pretty hot, but very tonally rich (unbalanced coils). The Parker's are naturally on the bright side, so treble response isn't something I need to enhance, tube-wise.

Thanks for your help.

 

[Timbre Wolf]

For R-2, I would like plenty of crunch, but something that warms up if you lighten your touch or roll back the guitar volume knob. Can't say I really want any compression, unless it's fairly subtle.

R-2?

If this isn't a position that is microphonic- prone (2nd or third gain stage), you may consider trying a long-plate 12AX7. For what you describe above, plenty of crunch, less compression, not so bright, I'd recommend a '50s RCA black-plate 12AX7.

- Thom

 

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Thom,

R-2 as in Channel R-2. Are you suggesting the RCA for the V-2 slot, or V-1? In combination with an RFT ecc83 in V-1? In any event, the RFT's available on Ebay are all in Europe, about 3-4 weeks delivery. So I'm going to see what the Amperex Ecc83 does in V-1 before I order the RFT, as they should arrive this week. Do you recommend an 12AT7 in the reverb slot (as is sharpy'd on the amp chassis)? Just curious as to your thoughts on that.

Lawrence

 

[Timbre Wolf]

Thom,

R-2 as in Channel R-2. Are you suggesting the RCA for the V-2 slot, or V-1? In combination with an RFT ecc83 in V-1? In any event, the RFT's available on Ebay are all in Europe, about 3-4 weeks delivery. So I'm going to see what the Amperex Ecc83 does in V-1 before I order the RFT, as they should arrive this week. Do you recommend an 12AT7 in the reverb slot (as is sharpy'd on the amp chassis)? Just curious as to your thoughts on that.

Lawrence

Lawrence -

I was trying to match the b-p RCA to your tonal description. Personally, I probably wouldn't use the RFT and b-p RCA in series with each other, but you never know what exact combination works best. The best approach is to have some archetypal samples on hand, and try them out yourself. The RCA is on the darker side of the spectrum of early-breakup long black-plate 12AX7, and can be helpful when such a character is wanted, usually in a later gain stage (microphonics potential is reduced).

Please remind me what V1, V2, etc. do in the circuit, if you want specific recommendations. As for the reverb, that must have a 12AT7 - reverbs are very particular.

- T

p.s. I see that Tubemonger is selling RFT for a reasonable cost: http://www.tubemonger.com/RFT_NOS_ECC83_12AX7_E_Germany_Great_Guitar_Tube_p/552.htm Though I'm not affiliated, I have nothing but the highest regard for Tubemonger's professionalism

 

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Thom,

here's a list of tube functions from the manual:

V1A = Input stage
V1B = Tone recovery stage (post tone controls)
V2A = Third gain stage (Rhythm modes) and Fifth lead gain stage
V2B = FX return stage
V3A = First Lead High Gain Stage
V3B = Reverb return
V4A = Second Lead High Gain Stage
V4B = Reverb send
V5 Phase inverter

Anyway, I plan to take it slow... going to add the Amperex when it arrives this week to the V1 slot, and see where that gets me. I like the idea of something a little darker, like the RCA description, maybe in V3. I might give that a shot. Thanks for the link, as I wasn't familiar with that outfit. Price is in line with what's on the Bay.

I figured the 12 AT7 slot wasn't something I should try a different tube in, hence the labeling on the chassis.

 

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So here's what I wound up with.

V-1 = 1961 Amperex (Holland) ecc83
V-2 = NOS Amperex (England) ecc83
V-3 = NOS Telefunken (branded Fisher) ecc83
V-4 = NOS Mullard CV4024 (12 at7)
V-5 = NOS Amperex (England) ecc83

And I now have about 10 spare ecc83/12ax7's. JJ's, some Groove Tubes (re-branded Sovtec's), NOS RCA and Sylvania, and a back up for the Mullard.

Couldn't be happier with the sound, now. The Clean channel is warm and round when played softly, and has a bit of purr if you use more attack. The crunch channel has more depth and better dynamic response than before, and it's easy to dial in the amount of distortion desired. The lead channel sings when played lightly, and growls and screams (in a great way) with a harder touch, very focused and a little compression. Using the EQ as a boost for any channel (on the foot switch), upside down "V" (just to be different). 8)

I tried all kinds of combinations, and this one worked best over all for the tones I like. The amp is much quieter now, too. Nice bonus.

Thanks for your help, Thom

 

[Timbre Wolf]

Couldn't be happier with the sound, now.

I'm glad to hear this. You've got quite the lineup of tubes, there. Enjoy!!

- Thom

 

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Yeah, I decided to just get a variety of things to try. I was a bit surprised at the final lineup... I thought I'd find a home for at least one of the RCA's. I suppose I could try it in the V-5 slot, that's the only place I didn't try an RCA. But frankly, I'm happy where it is. Now she's a beauty inside and out. 8)

Figured Bubinga dovetailed cabinet, curly maple face by your truly...

 

[Timbre Wolf]

Now she's a beauty inside and out. 8)

Figured Bubinga dovetailed cabinet, curly maple face by your truly...

Absolutely beautiful!! You did a fantastic job on that - a playable work of art.

- Thom

 

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Thanks Thom. I'm a part-time custom furniture designer and builder, so I decided to use some leftover bubinga from a furniture project. I rarely see bubinga so strongly figured, so I decided to do something special for the Boogie. She turns a lot of heads.