#1
She's on the way to the music shop now mhm.

I want suggestions for El84's/12AX7's for the AC30. Not sure if the stock tubes will be garbage or not. People seem to suggest JJ's all-round, as well as Telefunken preamps. Any suggestions would be appreciated. I really just want a spare set of power tubes on hand/make the stock set the spare set.

Also, do I need to buy the EL84's in a matched pair or quad?

And also, do I need to/how do I bias the amp?
forget college loans, need to pay off ac30 first
Last edited by Will Lane at Jun 8, 2015,
#2
If you don't mind spending a bit more, RFT EL84 are very good and reasonable for NOS EL84's

tubedepot has a really good deal on USA made 12ax7 pulls for $19.99
www.tubedepot.com/products/us-made-12ax7-preowned

JJ are alright for new production, but I have had some issues with a few different tubes. The new Mullard CV4004 gets some very good reviews from NOS tube dealers.
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#3
JJ EL84s are all I use. Ei used to be a contender while they were in production, overpriced now. RFT used to be a good deal when they were the last of the widely available NOS tube, but now stocks are all dried up and they're 3X the price of a quad of JJs. Not worth it IMO. They sound better but I don't think the longevity is enough to warrant the prices.

12AX7s - buy NOS if you can. Old production preamp tubes do tend to last much longer, and they tend to sound lots better than most new tubes. Most NOS tubes are going to sound great, which is good because you're probably not going to be able to be super picky about brands given their prices. If you're lucky enough to find an old stash, or can afford market prices, my favorites are Telefunken > RCA > GE > Everything else, having tried most of the major manufacturers except for the outrageously hard to find Mullard/Bugle boy AX7s.

Whichever you choose, make sure you get some tube dampers or go to a hardware store for silicone O-rings to make your own. Rattling leading to microphonics is a big problem with combo amps.

What I'm most worried about, though, is that you didn't ask about rectifier tubes, which means you probably paid too much for a C2...
#4
ac30 is cathode-biased as far as i'm aware, so doens't need to be biased
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#5
It's a brand new amp. The stock tubes will be fine for 4-5 years. Shop in 2019.
Not a bad idea to keep 1 matched pair of EL84s around just in case though. JJ
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY
Last edited by Cajundaddy at Jun 8, 2015,
#6
Quote by Dave_Mc
ac30 is cathode-biased as far as i'm aware, so doens't need to be biased

Correct.
AC30s don't need to be biased.

Quote by Cajundaddy
It's a brand new amp. The stock tubes will be fine for 4-5 years. Shop in 2019.


Stock tubes in my AC30 were EHX.
They were alright but I liked the sound of the JJ's I replaced them with.
The JJ's are a little bit darker.
I'd get the JJ's and save the stock tubes for backups.

These guys have a good selection.
https://www.eurotubes.com/store/pc/viewCategories.asp?idCategory=20
Last edited by CodeMonk at Jun 8, 2015,
#8
Well, maybe good selection was the wrong term. My bad.
When I bought them, they had them sorted for like "Max HeadRoom", "Standard", "High Gain".
And yes, they were all JJ's.
I meant that you have a selection as to the results you want to get, as long as you want JJ's.
Last edited by CodeMonk at Jun 8, 2015,
#9
Quote by CodeMonk
Well, maybe good selection was the wrong term. My bad.
When I bought them, they had them sorted for like "Max HeadRoom", "Standard", "High Gain".
And yes, they were all JJ's.
I meant that you have a selection as to the results you want to get, as long as you want JJ's.


You should expect that your selection of tubes will narrow, rather than expand, in the future. And/or the price will go WAY up. Not a bad idea to put away some stock if you plan to run tube amps past the next decade.

Worst case, you'll make some money from the people who are looking for "NOS JJ's" at some point in the future <G>.
#10
Oof, if I run out of tubes and we get to the point where 2015 JJs are at a premium, I'm going to stick my fingers into a live filter cap bank until jesus comes to take me.

That, or digital modeling. One or the other.
#11
Quote by Roc8995
-useful info-

Whichever you choose, make sure you get some tube dampers or go to a hardware store for silicone O-rings to make your own. Rattling leading to microphonics is a big problem with combo amps.

What I'm most worried about, though, is that you didn't ask about rectifier tubes, which means you probably paid too much for a C2...
Never heard about tube dampers. How would I go about making them from sili o-rings?

And yeah, I bought AC unit through the store I'm working at. I should be able to get a really good price, 10% discount as well as the owner is able to sell for less than the market price, and purple tolex.

And asking once more, quad or duo? Or just go ahead and get a quad anyways? I think I read somewhere that the biasing effects all power tubes, not a bias for each pair. So I would think matched quad.
Last edited by Will Lane at Jun 8, 2015,
#13
O rings are tube dampers. Get the right size (19mm, I think) and roll them on! 2 per tube is usually sufficient, you can use 3 for the power tubes if you feel like it.

You've got four power tubes, so...matched quad. Biasing and matching aren't really related in the way you're imagining they are, and anyway most tube places won't charge any more for a matched quad, so there's no point to not getting all 4 matched.
#14
Sorry for the death-bed bump.

How do the preamp tubes talk to each other? V1, V2, and V3? I'm thinking about putting a Tung-Sol 12AX7 in V1 to see if I can get the amp to open up a bit. What about V2 and V3? Gain and Phase Inverter? I'm putting JJ's in the power amp.
Last edited by Will Lane at Jun 18, 2015,
#15
Find a schematic and follow the signal. It's often listed to some extent in the manual, too.

Not sure about the C2 specifically but based on other models I'd suspect it's:
V1A: TB channel stage 1
V1B: Normal channel stage 1
V2: stages 2/3 for TB
V3: PI