65Amps Soho went silent....need help

[lgehrig4]

ust came back from Alpha Audio in Mystic with a Soho that was on consignment. Plugged in and within 30 seconds there was pop and then dead silence.

Fuses are fine
Tried with/out footswitch
Tried with/out master engaged
Tried new pair of EL84's
Tested guitar cord

Absolutely no sound. I called Alpha to tell them and they said that it worked fine while there. I have 7 days to rectify this or return before they pay the seller. I would prefer to keep and fix it if it's something minor, but I'm not putting more money into the amp by bringing it to a tech so if you guys could help me troubleshoot it would be appreciated.

I called 65Amps, but I don't expect a return call this weekend and I would like to get this sorted out this weekend because its tough for me to do anything during the week.

V1 - EF86
V2 - 12AX7
V3 - 12AX7
V4 - EL84
V5 - EL84
V6 - EZ81

Like I said I already tested the EL84's. I doubt a bad 12AX7 in V2/V3 could kill the sound completely, but I'm not sure. I'm hoping it's either the EF86 or EZ81, which are 2 tubes that I am not familiar with or have sitting around to test.

Thanks in advance!

[Milkmansound]

I would just return it - should not be your responsibility to troubleshoot and repair.

or take it to a tech and send them the bill

[lgehrig4]

turns out it was just one or both of the 12ax7's (V2 & V3). Not sure which because I replaced them both.

I never had a situation where a bad preamp let to complete silence. I've had a power tube go and the sound cut out but never a preamp. Anyway, sounds great now.

[Stevem]

If you place both of those tubes back in the amp does both of the filament sections in each of them light up?
Its been cold here in the NE and if the amp was in a cold car for even a hour and you got home and plugged it right in, then the tube that gave up the Ghost may have just split open from the sudden expansion of heating up.
If a tube amp is at a temp below whatever room temp may be always give it 20 minutes of sitting time before you turn it on, no less taking it out of standby!
The cold to hot thing is also a great way to loose a output tube or two!

[mauiboy81]

Let me guess..... They were JJ's?

[matt h]

(deleted)

[M Fowler]

Let me guess..... They were JJ's?

How come my JJ's work great and not in just my amps but all the one's I've serviced?

[xtian]

Me too also, good luck with JJs.

[sixstringer]

What about JJs? I've used a lot of them and have had better tone, durability and reliability over other new-manufacture tubes. It's true that I have had a few fail and become microphonic but considering the volume I purchase, they are still the best I've found.

[mauiboy81]

I wish it wasn't so but I have had nothing but problems with JJ's. Maybe I just have bad luck with them because every time I have had a tube issue it has been a jj. Microphonics, shorts, cracking and turning white, pops, hiss, thunderstorm inducing reverb drivers. I have heard a lot of people say they love them and that they are the most reliable new production tubes but that has not been my experience. Where do you guys get yours from?

[M Fowler]

Yes I've heard some complaints too.

I think most of my JJ's have come from CE Distribution, Mojotone, Tube store and Tube depo.

When I need a certain part I add on tubes to the order so I feel it's worth paying all that freight cost.

[sixstringer]

Like mark, I get them from CE, but also from Eurotube. Both suppliers have been good about replacing defective tubes.

[Leo_Gnardo]

There was a long running discussion (and battle) on MEF @ JJ. I'll skip to the conclusions.

IF you buy your JJ tubes from a company that tests and matches up pairs & quads, you'll be much better off. Mojo was mentioned as one of the better sources. Now that CE have revised their "we don't accept returns on the basis of complaints of microphonics" I'm sure they would also be a good source.

Eurotube in Oregon - carries JJ exclusively. The owner of the company was one of JJ's first US customers, made a personal visit to the plant late 90's, and happens to be of Slovak ancestry. He "may have an advantage" in getting premium product delivered to him. I've heard Eurotube is a prime source of hi quality JJ tubes BUT offers no discount to trade/quantity buyers. I've also read a couple of negative stories from musos/techs who bought a couple of tubes (EL84), had problems (loss of vacuum), got replacements, had problems with the replacements, then got the silent treatment.

I get lots of tubes from Magic/Ruby. I've found their premium HG+ rated JJ 12AX7's to be as good a tube as you can find. One of the typical JJ problems in 12AX7's is a pop noise that can rival a Geiger counter in a really bad sample. None of that in the HG+ test rank. Some complain "they sound dark." Compared to the Shuguang China tubes which have a hi frequency "edge" that borders on a jingle or whistle, yes the JJ may seem dark. I find the JJ do give excellent full frequecy response WITHOUT that annoying Shuguang whistle, and are quiet enough to "fade to black" when there's no signal.

JJ had lots of problems early on. As late as 2004 I was finding octal base JJ tubes with skinny pins, so ridiculous they fell right out of any tube socket. And my first batch of 12AX7 were so bad they all got the hammer. There may be some of these earlies-but-baddies still to be found lurking on dusty shelves, and I hope nobody here gets any of them. Since then things seem to have improved a lot. Except for one: 5AR4 rectifier. I got several batches which ran perfectly well, then @ 2010 a batch where there was nothing but trouble. Since then I've switched to the Ruby 5AR4-C which, if I have my story right, is specially made for Ruby and no one else. Scarcely ever a problem with them.

[xtian]

Great info, Leo. Thanks.

[mauiboy81]

Yeah, thanks for the info. Most of mine have come from cedist. I haven't ordered any of them in quite a while. I really should have tested them as soon as I got them and sent back the duds instead of waiting. Oh well. I do like how they sound when they are good.

Aloha!