Musician Gear & Tech Discussion

Ok, retubing the equivalent of 2 Fender Twin Reverb Combos.

Got a pretty good recommendation of ;

1) 1 matching set of quad "winged" Svetlana/SED 6l6GC's (4)

2) 3 Tung-Sol 12ax7's in the V1, V2 + V4 position(s).

3) 2 Mullard/Brimar CV4024 (12at7) in the V3 + V6 position(s).

4) 1 JJ Tesla ecc83s (12ax7) in the V5 position.

The tech says this combo is the best for what we're playing.


The chassis is saying TOTAL LOAD of 4 OHMS @ 100watts RMS.

Does that mean I am looking for 2, 10" speakers, 8 ohm at 50 watts each?

Eminence legends 1058's ? (10", 8 ohm, 75 watts per)

2 Rajun Cajuns?

2 JBL d110-f's? (omg the $, pleaaase no..)

2 Celestion Vintage 10's? (no heritage in 10" I found so far)

Who knows which 10" speakers to avoid?

sounds like you tech has some great ideas for your tubes...

afa speaker...
series = 8ohm + 8ohm = 16ohm
parallel = 8 * 8 / 8 + 8 = 4ohm

iow no two 8ohm speakers will give you 8ohms.

what you probably want is two 16ohm speakers wired in parallel to achieve
- 16 * 16/ 16 + 16 = 8ohms... and 50 watts each would handle 100watts

or take two 8ohm sets in series... and wire them in parallel and get
16 * 16 / 16 + 16 = 8 ohm -4 speakers -so each could be 25watts

basically, series means positive connects to negative and the remaining pos and neg are your live and ground.

parallel means pos to pos and then to live
and neg to neg and then ground

http://www.termpro.com/articles/spkrz.html

Got a pretty good recommendation of ;

1) 1 matching set of quad "winged" Svetlana/SED 6l6GC's (4)
2) 3 Tung-Sol 12ax7's in the V1, V2 + V4 position(s).
3) 2 Mullard/Brimar CV4024 (12at7) in the V3 + V6 position(s).
4) 1 JJ Tesla ecc83s (12ax7) in the V5 position.

The tech says this combo is the best for what we're playing.

Go with what your tech has recommended, unless your budget and ears through personal experience says better. Then, again, you never know unless you try others, and/or different combinations.

The chassis is saying TOTAL LOAD of 4 OHMS @ 100watts RMS.

Does that mean I am looking for 2, 10" speakers, 8 ohm at 50 watts each?

Eminence legends 1058's ? (10", 8 ohm, 75 watts per)

2 Rajun Cajuns?

2 JBL d110-f's? (omg the $, pleaaase no..)

2 Celestion Vintage 10's? (no heritage in 10" I found so far)

Who knows which 10" speakers to avoid?

The Celestion Vintage are probably Chinese made now, and not 100% the same as earlier Celestions. A brand not mentioned too is Weber, usually a pretty good speaker.

If you have a way to test every one, do so, especially in the real playing environment, especially since the sound is subjective, AND most likely isn't the same as in some showroom.

I'm not fully aware of any 10" speakers to avoid myself though.

As far as impedance, it says 4-Ohm load.

(I use || for parallel and + for series)
1 4-Ohm alone = 4 Ohms (duh statement)

2 8-Ohm wired in parallel will give you that, ( 8 || 8 ) - 8/2 = 4

4 4-Ohm in a series-parallel will give you that, ( 4 + 4 ) || ( 4 + 4 ) - 4+4=8, 4+4=8, 8/2=4 OR ( 4 || 4) + ( 4 || 4 ) - 4/2=2, 4/2=2, 2+2=4

4 16-Ohm in parallel will give you that ( 16 || 16) || ( 16 || 16 ) - 16/4=4

WITH speakers rated the same impedance:
Parallel: divide the speaker impedance by the speaker count.

Series: multiply the speaker impedance by the speaker count.

Power for each speaker will be divided equally between all speakers.
100W 1 speaker = 100W min, 2 speakers = 50W min each, 4 Speakers = 25W min each.
Personally, if you plan on overdriving the power amp, go with higher power speakers than your minimum.

I hope this helps at least in the impedance category. The exact speaker count is up to you, and what your cabinets will hold if you use existing cabinets.

The only thing I would question Scott is the CV4024's. My guess is that they're being used for reverb driver and PI. Great sounding tubes.. Not durable at all. If that is what they're being used for it's an expensive venture for a volatile product in my opinion.

I quit using cv4024s for a few reasons. But the number 1 reason was how prone they are to going microphonic.

I'm not going to get into a whole NOS thing here. If you ever decide to go that route, I'd be willing to help you, but it's a much longer process than just going to a store and purchasing tubes and popping them in.

Since it's your tech making the recommendations, I would have to guess he has the tubes on hand. Just be watchful of those particular tubes. If you feel like you're hearing any microphonic activity, those would be the first I'd check as the source.

In my opinion, a better reverb driver is a GE-JG 6201 12at7wa triple mica. They're much quieter, a WHOLE lot more durable, and you don't sacrifice very much in sound. Just a little midrange compared to a cv4024. The lows and highs actually sound better to me. Keep in mind also, that older Fender amps were built with the intention and recommendation of using GE tubes. Does that mean that GE's are a better choice for every V-slot?? Not exactly. But it does seem to be the case for getting a correct pure vintage Fender "reverb" sound, which is the highlight of reverb series amps.

In the PI, if you're going to go that route, CVs do sound very nice. I don't think your tech is steering you wrong as far as sound.

CV4024s will brighten the midrange and give the reverb a nice open sound. I have no problems with their tone. But don't be too surprised if they're the first to go south on you. And this is not something that's a reflection of the tech. I've had perfectly good tested NOS CVs just konk-out on me for whatever reason, and they were supplied by very reputable vendors.

This is a buyer beware purchase in the NOS world. You're dealing with the fine China. The same can be said for CV4004s (the 12ax7 version) as well. Although they carry the "MIL spec" tag, I would have to say that they are the most brittle I've encountered that carry that description. Great for the studio, not so good for gigging (in my opinion).

It's supposed to be (2) 8 ohm, 10" wired in parallel for 4 ohm impedance.

And it's not exactly 4 ohm after, it's like 4.5 or 4.6 ohm.

Sorry, I neglected to mention I was using (2) 10" at 8 ohm to get 4ish ohms.

Shredd, someone else mentioned the cv4024s as going microphonic very easily. Thanks for mentioning that again, I just barely heard him say it and it didn't register at the time.

I was just going to do a whole JJ's Tesla set of 10 tubes but it's 140$.
And at (x2 sets), I don't really want to spend that much considering I still need the speakers.

I just ran into a guy that has 300 vacuum tubes for sale for 50$.
He says they are from an old GE repairman's kit that has been in a basement for 40 years. The problem is he is 1.5 hours away and he has no tube tester, nor does he even know if he has 4 6l6's, 4 12ax7's and 2 12at7's in the 300 to get even 1 refit from top to bottom.

DO I PONY UP THE 50$ and bite down or should I do something else>?

And I guess it sounds like what I had thought, 2, 50 watt, 8 ohm, 10" speakers wired in parallel for 4.* ohms.

I see 2 Eminence Rajun Cajun's calling my name. (10", 8 ohm, 50 watt and he has 2)

And you know you have me really quaking in my boots, I am considering going FENDER tubes as I want that vintage sound.
(One chassis is already 90% loaded with FENDER tubes, but I thought it was just someone being cheap)

Keep the advice coming, lord knows it hurts but it's a good kind of hurt..lol

(If ya know how to play, that sure as hell doesn't mean you know jack about amps/tubes/speakers. I am living proof!)

Feels like the itch you get on a broken leg..bad but getting better.

Shredd, someone else mentioned the cv4024s as going microphonic very easily. Thanks for mentioning that again, I just barely heard him say it and it didn't register at the time.

I was just going to do a whole JJ's Tesla set of 10 tubes but it's 140$.
And at (x2 sets), I don't really want to spend that much considering I still need the speakers.

I just ran into a guy that has 300 vacuum tubes for sale for 50$.
He says they are from an old GE repairman's kit that has been in a basement for 40 years. The problem is he is 1.5 hours away and he has no tube tester, nor does he even know if he has 4 6l6's, 4 12ax7's and 2 12at7's in the 300 to get even 1 refit from top to bottom.

DO I PONY UP THE 50$ and bite down or should I do something else>?

And I guess it sounds like what I had thought, 2, 50 watt, 8 ohm, 10" speakers wired in parallel for 4.* ohms.

I see 2 Eminence Rajun Cajun's calling my name. (10", 8 ohm, 50 watt and he has 2)

And you know you have me really quaking in my boots, I am considering going FENDER tubes as I want that vintage sound.
(One chassis is already 90% loaded with FENDER tubes, but I thought it was just someone being cheap)

As far as the tube lot goes.. It's just a gamble. I really can't give you any advice on that in good conscience. I don't think it would hurt the guy to at least let you know if he sees any of what you need within his collection. Either way, if you don't have a tester, how are you going to know what's usable or not? Most of the time, it's not a visual thing. I would say that if you had a way to test them, if even 5 of those tubes are good, you'd be able to make your money back by selling them on ebay whether they were what you need or not. Some Tube CB Radios use odd tubes you never hear about in the guitar amp world and can fetch some really descent coin.

It's just a tough call man.. Just depends on how well you know the guy. I'd call him up and ask him if he sees any of these in his lot:

12ax7
12at7
6681
6201
5751
ecc83
ecc81

If he says no, or that he doesn't know, walk away.

As far as the Fender tubes go. That depends too. If they're NOS, they could possibly be GE, you can always post a pic for me to take a look at. I think modern Fenders are GT right now.

lol I asked him if he at least had the single refit I needed.

4 6l6's

4 12ax7's

2 12at7's

He won't reply and that just tells me he doesn't want to say or he can't read a tube.

Either way he can go suck a lemon. lol

I was born at night, but not last night..