Rickresource Rickenbacker Forum

I have an older AC15 with blue alnico speaker. Apologies in advance for my ignorance in the world of tubes.

Years ago I was in a band (rhythm guitar - oldies, blues, invasion, mostly played a RIC 360 and/or an old Epiphone humbucker solid body)
and experimented with different tubes with some success and some disappointment. It was an eye-opening experience... I never knew
what a art tube selection can be and just what a HUGE impact different tubes can have on the sound of a given amp.

Unfortunately for me, I never kept track of what tubes worked for me and what didn't.

My sound tastes lean toward clean sweet and mellow, NOT dirty metalish and distorted.... if that helps.
One time (way back when) I happened to hit upon a tube set that was sooooo nice.... very smooth
and sweet... almost jazzy. But as I said, I have NO idea what those tubes were.

Now I'm looking to bring the AC15 out of mothballs and want to start with a fresh set of tubes.
What should I buy????

Thanks in advance for any guidance you tube experts can provide.

Kent tube shopping is fun. I would get 2 x JJ/Tesla ECC83S and
2 x JJ/Tesla EL84 in a matched pair.

Thetubestore is one of may favourite places to buy online and they have good customer support and consultation. There are other suggestions here.

http://store.yahoo.com/thetubestore/vox-ac15cc.html

Thanks..... here's someone who went through an AC15 experience and echos what you say about the Tesla EL84s

http://endofthegame.net/2011/09/02/vox-ac15-mods/

I eventually decided to take the plunge into the NOS tube world (New Old Stock), as these tubes are unanimously praised as having superior longevity and tone. NOS tubes are tubes from as far back as the 60s, .....

New production tubes however are usually no more than $10 a tube. I ended up purchasing 1 NOS RCA 12AX7, 1 ANOS Mullard 12AX7 and 2 NOS Tesla EL84s (Tesla is the company that JJ’s eventually took over)......

I ended up purchasing 1 NOS RCA 12AX7, 1 ANOS Mullard 12AX7 and 2 NOS Tesla EL84s (Tesla is the company that JJ’s eventually took over)

All I can say is WOW, the difference way night and day. It was as though a thick blanket was taken off the amp,

brammy wrote:Now I'm looking to bring the AC15 out of mothballs and want to start with a fresh set of tubes.
What should I buy????

Thanks in advance for any guidance you tube experts can provide.

Kent, how long has it been since you last turned the amp on? You may need to do more than just put new tubes in it and rock out. Possibly some new caps and resistors to bring the amp up to good working order.

Caps and resistors? I didn't know they went "stale" ..... hmmmm, maybe. Its been over 5 years. Do you think that maybe I should buy the tubes and then take it to a pro to have a full overhaul?

Well, resistors don't often go bad, but caps, especially electrolytic types can. They're probably OK after only 5 years, but it depends on how old they are overall too. Be prepared to switch it off quickly if you see anything that looks wrong (like smoke of tube plates glowing orange)...

Plate resistors can go bad from all the heat they are subjected to, being so close to the output tubes.

My music store buddy says I should try a 12AY7 or a 12AU7 in V1 for a warm, ultra clean tone. Since they have a higher headroom than a 12AX7 the amp wont break up as quickly. The trade of (naturally) being that the amp's overall max volume will be lessened.... but thats ok with me.

Comments?

Those tubes have lower gain which is why you get a cleaner sound, they don't overdrive the phase inverter as much as a 12AX7 would.

You should be just fine with the caps in the amp for awhile yet, but please make sure to play the amp at least a couple times a year to keep the caps in good shape.

As far as tubes go, anything that functions well and lasts for a good amount of time is fine. That said, NOS tubes definitly will last longer than new productions tuff, and often sound better too. I like GE 6BQ5's in my AC30 a lot, but as they aren't made anymore, they are expensive and hard to find. So I started using EI EL84's years ago, which are fantastic and sound almost as good, but sadly they are now out of production too. The best sounding and most reliable new manufacture EL84's these days are the JJ but to my ears they pale in comparison to the others I mentioned. For the 12AX7's, there are lots of good NOS stuff and new manufacture stuff to choose from. For NOS stuff the Euopean stuff is generally better quality and better sounding than the old American stuff, but the American stuff is still very good. For new manufacture, the reissue Tung Sols and the JJ are good. You can try a 12AU7 or 12AY7 in your amp also without any damage. Whether you like the sound or not is something only you can decide.

Greg

Thanks everyone.... I'll let you know how it goes.

ok.... I'm back again.

I have "Twisted Wires" in Eugene OR doing an overhaul on my 1999 VOX AC15. But it is still up to me to select the preamp tubes.
So far, I have position 1 selected with this recommendation from Tube Depot:

If you are looking for a tube with less gain, the I suggest using the 5751. The 5751 has 30% less gain of the 12AX7. So, it tames the preamp section down, but you retain all of your tone. I would not suggest using a 12AU7. It has been my experience that the sound is not very pleasant.

Would anyone like to take a stab at filling in positions 2-5 for me? It seems like my options are 12AX7, ECC83, 12AU7, 12AT7, 12AY7, 12AV7 .... ???

1) Jan 5751 http://tubedepot.com/nos-5751jan.html
2)
3)
4)
5)

I really love the 5751, the amplifier tamer.

BTW.... here is the 1999 VOS AC15TBX we are talking about.....

http://www.voxshowroom.com/uk/amp/ac15tbx.html

ok..... based on various advice, here's my preamp tube selection for the VOX AC15

V1) Jan 5751 http://tubedepot.com/nos-5751jan.html
(I'd use a Mullard 12AU7 but its way too expensive) http://tubedepot.com/nos-12au7-mullard50s.html)

V2) 12AT7 (Electro-Harmonix 12AT7 http://tubedepot.com/eh-12at7.html)

V3) 12AX7 (JJ ECC803s / Hi-Performance 12AX7 http://tubedepot.com/jj-ecc803s.html)

V4) 12AX7

V5) 12AX7

------------------

ok.... here's what happened today. I went to talk to my music store buddy (Nate at "Gracewinds" in Corvallis.... great guy).
I was asking him for tube advice and he did a demo for me. Using a Fender Princeton Reverb just like this one:
http://www.youtube.com/watch?v=rjTGamDz_BM
he first played it with the standard issue 12AX7 in the V1 position.

THEN he switched out the V1 preamp tube with a JJ 12AU7.

WOW....................................................................................................................
WHAT A DIFFERENCE!!!!!!!
1) yes, with the 12AU7 the max volume was decreased (if you really need huge volume that can be accomplished with a booster)
2) BUT.... the TONE was unbelievably made better.....

Its always hard to describe sonic stuff in words but the difference was HUGE....
more full, rich, pleasant, surrounding..... so obviously better it blew me away.
At higher volumes it stayed so sweet.... didn't break up.
At lower volumes you had more area to play with since (by definition) it didn't get as loud as quickly.
If you like that "break up" sound you can always achieve it with pedals.
TRUST ME..... this concept of putting a "less gain" preamp tube in the V1 position really has merit.

I hope some of you will give this concept a try.

Anyways... thus ends the preamp tube saga for now.... I'll let you know how it all sounds when I get the amp
back (from its overhaul) and get the new tubes in. I cant wait.... its like getting a whole new amp.