Crate VC 30 Help Needed

[semihollow]

Hello everyone. This is my first post here-- I have read a good deal of the posts and people here seem very informed.

I have an 'old' Crate VC 30 amp (VC 3112B) that I bought brand new in 97 or maybe 98.

It has been my 2nd and even 3rd use amp, and after 10 years or so, the tubes have finally met their sonic end (muddy, bad definition, etc).

I have never replaced tubes.

I took the thing apart, and my goodness it is NOT user friendly. At last count there was 5000 screws to remove the back, and the main PC board comes away from the chasis too!

So it takes 4 12AX7 preamp tubes and 4 EL84 tubes.

I bought 4 'matched' Groove Tube EL84's. They are all rated '6' on their scale of distortion ceiling. By 'matched' they say they are matched and come two together in a box, both boxes of 2 are taped together.

I bought 4 12AX7 MesaEngineering tubes, but they are not matched-- I just bought em.

Those were the only options (brands) I had locally.

I have not yet installed these tubes.

My questions for the esteemed forum members:

1. What should I watch out for to not kill myself while installing these tubes? (Keep in mind everything is exposed)
2. Do I need to 're-bias' these tubes or am I ok with what I bought?

Any comments and advice is very much appreciated!

P.S I have unplugged and disassembled the amp several days ago. Also, for what it is worth, I'm a amp tech newbie, but certainly NOT a musician newbie.

[sumgai]

semi,

Hi, and welcome to the NutzHouse! ;D

1) As I recall, the back panel needs to come off for easier tube access, which might leave the inner chassis exposed. (There have been a few design changes over the years, this may not be the case with your amp.) If so, you need only keep your mitts out of the innards, and all should be well.

The tubes are outside the chassis, just remove them (gently!), and insert the new ones, again gently. Make sure that the blank area between two of the pins fits over the same blank area on each socket - this holds true for both kinds of tubes. Rocking them in a small circular motion helps to get them out, but going back in, that won't be necessary - straight in will suffice.

2) No bias adjustments are needed (nor are any easily available to the user), just plug 'em in, and let 'er rip!

HTH



sumgai

[ccso8462]

Hi semihollow, and welcome to the forums! Glad you like what you see.

The Crate V series are great amps. The number 1 safety item is obvious: Make sure the amp is unplugged! ;D The bias question is not so easy. If the amp is self-biasing, it's basically a plug-n-play situation. If not, the tubes will definitely need to have their bias checked. I'm sure that someone that can answer about the biasing will be along shortly.

Again, welcome aboard! It's a great place.

Carl

PS: Oops! Looks like the big gai beat me to the first post. I've got to learn to type faster!

[semihollow]

Hi guys, thanks for the advice.

The version I have is discontinued, and it is not as user friendly as the newer versions in terms of ease of replacement. In my version, when I took the back off, I NEEDED to also remove it from the PC board and take the PC board out as well.

Anyway this eases my mind in terms of no biasing needed. Thanks!

I am a very simple sonic personality, and I want to 'upgrade' to an emery amp (ha. some would consider that a complete downgrade. What?! No effects loop??), but that is for another post...

[sumgai]

semi,

An amp that needs to be disassembled like you've described, just to replace the tubes? That would be discontinued in a heartbeat. In fact, I'd bet that the designer that snuck that by the marketing department (who are the ones that hear feedback from the customers) is probably working somewhere else these days.

I've never seen such a thing, at least not in a Crate Vintage series. Tell me, can you perhaps take one or more pictures and post it/them? I'm very curious here........ Not that I disbelieve you, but it would be nice to fill in the blanks in my knowledge base.


sumgai


p.s. Carl - hehehehehe, all your keystrokes are belong to us!

[semihollow]

I have some pictures that I took when I was starting the dissasembly, but they are not entirely exhaustive.

When I get my camera back from a friend I suppose I could post them (its a pain in the butt with that photobucket thingy).

But to summarize: There was a total of 29 (YES, 29) screws that need to come out to switch the damn tubes.

The PC board is NOT attached to the 'box' of the amp-- it is attached by three screws to the back panel of the amp. This back panel then attaches to the 'box' of the amp.

HORRIBLE design. HORRIBLE. In fact, Nobody I have ever spoken to knows Crate made a VC series-- they only know the V series.

This is likely due to the improvement of the physical design-- I highly doubt they made any sonic changes from the VC to the V series.

Anyway, the new tubes sound much better-- the bass is richer and they sound musical.

[ccso8462]

Semi, that sounds like a real monster to work on! Glad the new tubes worked out for you. Good to know about the VC series for those of us that might look at used amps. Thanks for the heads-up.

Carl

OK, Sumgai, I figured out how to hide my keystrokes from you. Just like this: "________________________" See? it works!

[sumgai]

Carl,

OK, Sumgai, I figured out how to hide my keystrokes from you. Just like this: "________________________" See? it works!

Yes, until I do a 'quote message' for a reply, then it all shows up, nice and neat, as if you'd never hidden it at all!


sumgai

[ccso8462]

Rats! Back to the drawing board! Let's see, I think I have a contact in the gov't that can help. We'll see...