NOS versus new production tubes

[NoiseAnnoys]

the voltage selector isn't easily accessible anymore but it's still there. I'll ask my tech about it next time I take it in.(

If you want to go the step up transformer route, you could have him wire up the 245 tap directly, and bypass the selector. Those vox voltage selector gizmos are kind of sketchy anyway.
-J

Yeah. I haven't read anything good about them. I was kind of idly thinking about having him just set it permanently to 115, but that's starting to sound like a better option in some ways.

Vintage correct, stock AC50s are kind of death traps, apparently.

[jimboyogi]

That's a bummer that there's no EL34s even remotely close to old specs around.

Have you thought about/tried the JJ KT77?

http://www.vintageamps.com/plexiboard// ... 65&start=0" onclick="window.open(this.href);return false;

[øøøøøøø]

Ominous words from Oliver Archut today:

Hello guys,
the situation will get even get worse in the next couple of years, since the crumbling of the CRT market, the companies in Russia that made the raw materials are stopped production due the fact that nobody wants CRT based monitors anymore and that was the last big domain for inexpensive vacuum materials.

Every year I buy a bunch of in production valves and sorry to say, none of the current EL34, 6L6 variation or EL84 are even close to a NOS tube of western origin.
The lifetime is the first problem, the best EL34 I tested works for about 3 month, that they go either deaf of die in a light of glory and melt down. I recently retubed the first amplifier ever sold commercially (28 years by now) with EH 6V6 and from the 6 I bought two where bad, and two did a melt down. Ended up and bought a bunch of EMI made 6V6 type tubes and they work great.

From the last batch of EL84 I bought for Oahu amps, half of them were bad right out of the suppose to be computer tested batch.

Regarding NOS tubes, every month good batches of GE, Sylvania and Mullard lots show up, the question is just the price. $120 for a genuine 6L6GB that will last without a problem for 10 years? I think it is a fair price given the fact the pain of replacing junky in production tubes.
It is getting harder with Telefunken or RCA tubes.

Best regards,

Oliver

[sookwinder]

We were discussing where to buy NOS valves a month or so back in this thread and I made the comment that bargains can still be had on ebay if you watch and watch and do your homework.

Well I ahve been "stocking up" on EL34s / 6CA7s for a project I have planned for 2012 (while the aussie $ is worth 1.07 US$ ) and managed to win two NIB/NOS Mullard EL34s branded as RCAs ... they are the XF2 variant , probably late 60s to early 70s ... for $100 for the pair .. that's $50 each ... they go for anywhere from $100 - 150 for a single valve on ebay normally , sometimes even higher ...

get this ... then the seller asks if I want two more of the same, but with the boxes slightly eaten by mice... for $45 per valve ... as I said bargains can be found

[OffYourFace]

excellent score David!

[øøøøøøø]

nice find!!!

[jimboyogi]

Bingo David! This project is getting closer and closer

[Jay]

Nice deal there! I have a pair of the exact same XF2 Mullards (though Mullard labeled) and one is fantastic in the Champ I modded so I imagine you'll be pleased as well. I'd also recommend looking for an old Tung-Sol 5881 for your build. I find one of those to sound the coolest in mine—albeit by a slim margin over a 6V6 or EL34.

[sookwinder]

I really enjoy this amp design/building thing...

Here I am looking (and finding parts) for the project for next year (PR with 2 x EL34) and realising that I need to do a lot of reading and underatnding of designs that have gone before, when the current project (Champ Reverb with EL34) is still half way finished ...

[idiotbear]

The '69 Pro Reverb I have my eye on has a lot missing: it's trashed. But it's also cheap, so I'm going to try my hand at restoring it.

It seems that theampdoctor's TAD tubes get good reviews - but it'd be great to know if anyone has any experience of using them? I'd like to avoid the cost of NOS if at all possible, but then I also want to avoid false economy. If I'm going to have to replace a bunch of early blown tubes, then maybe NOS is more cost effective.

Anyway. TAD opinions?

[ludobag1]

i have read all and it is really interresting
i would like just to tell me a story between nos and brand new tube
i trust in nos but you must know what you buy or you will be not happy

beguin of the story
i have buy this fender reverb reissue from 93 us model 110 v with the 220 110 v transformateur

the guy give with this spare tube


in it i have a 12at7 rca ,a fender 12ax7 and a 6v6 tad

it sound good but i have a hiss coming from the verb ,when the mix was at 3 and you push the volume on amp a larsen appears ,i swap with the tube in my deluxe and found it is the 12at 7 rca was the trouble
then i go to buy some tube for spare and i find some groove tube (12ax7 and 12at7 )at a musical store and the store work with a tech then i visit him and buy also tube 12ax7 EH and 12at7 syvania (nos) for sure
result the groove tube works don't know for how much time but my trouble is solved i can reput the tube in my deluxe that i have swap to try
the 12at 7 don't work ,i call the guy and (it is an asshole to be short) cause he explain me no refund on tube i could have make lot of thing with ,bla bla then i go to him and tell him that i have swap with other tube and it is his tube that doesn't work (the trouble is no reverb on my unit ,the 12at 7 is the tube for the tank then it is the culprit)
then he give me another 12at7 syvania (same looking ) and you know what ,it doesn't work too ,then i have visit another technicien to make repair my bass amp and ask him to test this tube
answers he have try in his head(he repair and build amp) and the tube don't work too

all of this to say ,if i can i will buy totally new tube cause i think it is rare to have one not working ,for the nos it is really risky cause lot of guys sale old tube ,not tested ,or maybe worst old tube out of life they have find in a box that come from an old technicien and this box was the box where not working tube where stock

don't know for you guys but for me in France there is not lot of good tech who can test tube ,and if you put a dead tube in a good working amp the damage could be grave for the amp ,shortcircuit ect...
i have seen lot of auction for tube but i haven't the knowledge to look at ?
for exemple

on this 6k6 the sylavania have a label writen on 38- 45 like the RCA ,but the third is Ge but no marking and more over no 6k6 marking on it then i don't know what it is ?

i have swap the 6v6 tad for the sylvania 6k6 to my taste the sound is better ,more hot

i see lot of auction for nos ,full tested ,90 % of life , or result in ma but where do you find chart to knew if the tube is good enought to be use ?
for exemple a 12at7
it is a rare saler who tell the caracteristics
fil= 13v
polard = -2,v
anode =250 v
10 mA-10 mA correspond à = 100%
résultats
10,8mA - 9,8 mA
10,0mA - 10,0 mA

cause lot said tested and you buy something you don't know if it is nos or uos or worst ready to dead

sorry for the book

also i have an old EL84 Mazda in a old radio can i try it in my little vox ac4 without too much risk ? ,if it work it is ok ,if it is not working will it blow something in the amp?