#1
So, for the past 3 months I've been without a preamp tube in the V1 position of my amp. I ordered an new one from my local music store but I've gotten no reply bar one phone call 3 weeks ago to let me know that one supplier didn't have it but they'd check the others.

So, I've decided to give up on them as this isn't the first time they've "forgotten" about me and my order. Now I'm going to just go to the largest music store in the country and get what I want.

The tube I'm replacing is a Sovtek 12AX7LPS, the other three preamp tubes are JJ 12AX7's. My amp is a Peavey JSX. I'm going tomorrow and not just getting the tube of eBay etc. as I want it before Christmas as I'll be home from college then. So, I checked out their website and I have three options:

Peavey Super 7 Tube

Sovtek 12AX7WA

Sovtek 12AX7WB

From what I've read, the Sovtek 12AX7WB is my best choice as it's a higher gain version of the WA. As for the Peavey Super 7, I've never heard of it before.

Any thoughts?
#2
Here are just a few thoughts.

Don't buy a tube that has an amp name on like Peavey or Mesa. They don't make tubes, it is just rebranding. The Sovtek LPS were preferred in the Phase Inverter positions not V1 I believe. Looks like the Sovtek WB's are made in Russia, which is good thing. I'd probably go for those. Can't speak to the others. I personally would not buy these kinds of tubes off eBay. Too much variance and probably not tested but what do I know. NOS tubes I would consider buying off eBay. Cathbard is a preamp tube expert maybe he'll chime in. My recommendation right now is JAN Phillips 5751s.

contact www.hotroxuk.com and ask for their recommendation.

hopefully they will work out for you as a tube supplier - most local shops are idiots when it comes to this stuff and end up buying tubes online anyway like the rest of us. Most of the tube suppliers I know will ship to you within 2-3 days with tested tubes based off of a recommendation that they hone in on.
Last edited by 311ZOSOVHJH at Dec 18, 2011,
#3
Sovtek's are crap. The WB is the better of them but still .... you can do a lot better.
Who knows what the Peavey is. It could be anything.
Get yourself a SED =C=
http://www.sed-usa.com/index.asp?strType=Content&strPage=12AX7

or better still find yourself a British, German, Dutch or American NOS tube.
http://tctubes.com/RCA-12AX7-long-gray-plates.aspx

Or take a punt on Ebay. I've ended up with a few microphonic ones from Ebay but at the prices you can get them for at times it's worth a gamble. You might even score a British Mullard in good order if you're willing to take a bit of a chance.
Gilchrist custom
Yamaha SBG500
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Cathbard Amplification
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#5
Any tube that can't handle being in a cathode follower shouldn't be in your amp so that's Sovtek out. Tbh I'd buy Shuguangs before Sovteks. The Shug EL34's in my JCM900 have been quite satisfactory. I've never used their preamp tubes but MC swears by them. I've been buying JJ's for the amps I build because they sound so good and in my own amps - well, as you know I have a bit of a collection of NOS tubes so why would I bother?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#7
Same. If JJ preamp tubes start to become dodgey I'm going to cry. The whole EL84 thing is worrying enough for an amp builder that makes EL84 amps. It's as scary as hell. If SED made eL84's I wouldn't be so concerned because it would only add a few bucks to the price but wtf am I supposed to do?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
Cheers guys! Hmm, maybe it isn't the V1 position in my amp then... When I bought this amp, the seller had just had it re-tubed with JJ's. I was told that there was one Sovtek 12AX7LPS preamp tube as it was one of the best tubes in that position. Just to clarify, the tube I'm replacing is this one (not my photo) which is the slightly taller tube cover in the back of this picture beside the power tubes (my photo). At the moment I'm running 3 JJ 12AX7's and 4 JJ 6L6GC's. Also, can someone explain tube positions to me if you have the time?
#9
That looks like it would most likely be the phase inverter. Get yourself a NOS 5751 for that. The phase inverter tends to be the first to fail so something with a bit of longevity is the go. A 5751 has less gain than a 12AX7 but in the phase inverter that doesn't mean much.
>> http://tubedepot.com/nos-5751jan.html <<
http://www.dougstubes.com/preamp-tubes/12ax7-ecc83-7025/jan-ge-5751.html


Tubes normally count from the one closest to the input jack.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#11
Yeah, listen to Cath. I also run a 5751 in my PI.

Every amp is different but generally:
V1 - handles clean channels and first input stage
V2 - V3 - V4 etc Gain Stages
V (last) is your Phase Inverter.


Like Cath said if you kind of trace your signal from the insert jack to the power tubes that is the direction your signal travels (generally)

That should be true for your JSX as well but would not hold true for a 6505 for example- those are set up differently.
Last edited by 311ZOSOVHJH at Dec 18, 2011,
#12
The last tube before the phase inverter is usually a cathode follower for the tone stack. You have to be pretty careful what you put in there. A Tungsol or a Sovtek WA is likely to die if you plug one in there.
Let me see if I can dig up a schematic for your amp so I can talk specifics. So it's a JSX is it?


Edit .... hmm, easier said than done. Somebody find me a schematic and I'll look it over.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Dec 18, 2011,
#14
Nah, we need a real schematic, not a half-assed block diagram.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#16
That's better. The tone stack isn't a cathode follower so that simplifies things a bit. If I owned one of those I reckon I'd go insane modding it.

V1 is common and has the tone stack hanging off it. Very odd but not a problem.
So here's what I'd do.
One of the 5751's I posted in the phase inverter.
Keep the JJ's everywhere else and experiment with V1.
Those Sovteks you listed in V1 would make it sound a bit brittle I reckon.
Something like these would be what I'd be going for in V1. This is a selection of the cheaper NOS tubes out there without having to go to Ebay.
http://tctubes.com/GE-12AX7-long-plates-OEM.aspx
http://tctubes.com/RCA-12AX7-long-gray-plates.aspx
http://tctubes.com/Sylvania-12AX7-gray-plates.aspx
http://tctubes.com/GE-5-star-5751-12AX7-gray-plates.aspx
Some damn good prices there. Worth every penny.

Edit. You might want to try a JJ ECC803 in V1 too. Buy a few different things and just experiment. You need spares anyway.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Dec 18, 2011,
#18
Probably ok. Looks like a rebranded RCA to me. Doesn't really look that NOS, look at the pins.
If I were you I'd just grab this:
http://tubedepot.com/nos-5751jan.html
It aint that much more expensive and you know it'll be tested on a calibrated tester and you can get a refund if there's anything wrong with it. It's on sale atm, I'd jump on it.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Dec 18, 2011,
#20
Well, in theory you should get a balanced one because it's going into the phase inverter but that's over-rated really. The circuitry itself around the valve is only going to be balanced within 10 or 20% so unless the tube is way out of balance it won't matter. It's only an extra $2 so you may as well get a balanced one I suppose.


PS: On the amps I make I pick a balanced one for the PI by ear using an A/B switch and I get great results. It really isn't that critical.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Dec 18, 2011,
#21
Update: I went to order it, the shipping doubled the price. I'm going to try get it elsewhere.

Update 2: I found UK a seller on eBay so cheap postage to Ireland.
Last edited by conor-figgy at Dec 18, 2011,
#22
It'll probably take longer to go to Ireland from the UK than the States.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#23
Quote by Cathbard
It'll probably take longer to go to Ireland from the UK than the States.


Perhaps, but £2 shipping is a lot better that ~$27.

Cheers again for the help, I really appreciate it.
#24
That is an outrageous postage cost. Things that size cost $9.60 in postage from the US to Australia. I greatly doubt that it costs more to there than here.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#26
So they are pocketing about $16 minus the cost of a little box. That's some expensive little box. You did the right thing, that's a rippoff.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#27
Well anyway, I got my tube and I'm quite happy. It's a pity there's no good retailer or tubes in Ireland. I've thought about it myself a couple of times but with college work and my complete lack of business experience and tune knowledge I couldn't make it work. Not to mention the fact that if it was a good idea, someone else would already be doing it!
#28
^

not necessarily. it seems like a cut-throat business. the internet and cheaper manufacturing has re-scaled everything. I don't think it is something I would want to get into. The quality of tubes changes quite a bit. Like a lot actually in the last 3 years that I've been following it. Crazy.

glad you found something that works.
#29
Apart from the JJ's I get sent over in transformer shipments from Chicago, most of my valves come from ebay. I've had a few microphonic ones but I've scored some real bargains too.
UK ebay often has some doozies. I don't like to buy off UK ebay because Royal Mail is so pathetically slow but that's where I got the Brimar 6L6's in my gigging amp.
You should take notice. Old European and British valves are the best thing money can buy. That region is the Mecca of the valve art. You're in the thick of it - watch the skies ..... err Ebay.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band