ampeg svt classic fault issue help

ohnoitsthebass · #1 11-12-2011, 12:54 AM

one of the house gigs i mix at has a 6 month old ampeg svt classic head, the fault led on the front of the head is blinking obviously meaning that it has an issue. looking for someone who knows or as owned one of these heads, need to know if its the power tubes, or a more internal problem. lets hear your experience with these and what it could potentially be wrong with it.
thanks alot

oinkbanana · #2 11-12-2011, 03:01 AM

RTFM
http://www.ampeg.com/pdf/SVTCL_OM.pdf
"if the amp detects a fault in the power tube circuit, the high voltage is turned off and the LED flashes between red and green. This usually indicates a bad power tube. the amp will remain in this condition until the amp is turned off"

so check the power tubes. I'd replace the bad pair.

T-Bird · #3 11-12-2011, 04:00 AM

Hi.

For an amp that's still under warranty, regardless of the make, the answer is pretty obvious, now is it?

The SVT tubes do not work in pairs, but in two banks of PP triplets, changing a pair will only result greater mismatch, making it difficult to bias the tubes. Unless that's Your goal, and the owner of that said amp for some reason don't want to use the warranty, change a triplet.

Regards
Sam

ohnoitsthebass · #4 11-12-2011, 10:53 AM

yeah i was figureing it was the power tubes. just wanted to get a second opinion from someone who knows a little more about these amps then i do. also regarding the warranty, dont have time to wait for it to be fixed, this amp needs to be used regularly and as a backup. and its the corporation i work fors money, they can afford it :P its more important that its working rather then the cash. thanks for your help guys

BassmanPaul · #5 11-12-2011, 12:01 PM

Quote:

Originally Posted by ohnoitsthebass

its more important that its working

Unless you get the amp seen to by a tech this is something that won't last long!!

T-Bird · #6 11-12-2011, 11:00 PM

Hi.

What Paul said.

The problem can be a number of things, not just a bad tube.

Quote:

Originally Posted by ohnoitsthebass

also regarding the warranty, dont have time to wait for it to be fixed, this amp needs to be used regularly and as a backup. and its the corporation i work fors money, they can afford it :P its more important that its working rather then the cash.

You're joking???

Have't You seen the numerous threads concerning the (seemingly) huge warranty work demand on the CP tube amps?

I blame RoHs, some blame the crappier than in the past tubes, most blame Chinese mfg, but the end result is the same, regardless. Those amps do need professional care within' the first year of operation and there's no way around that. Fail that, and You have a lemon in your hands for a long time.

Imagine a cold solder joint took one tube out.

You change that tube, a bank of three or the whole set.

That cold solder joint takes yet another tube out at the most inconvenient of times, at the middle of a gig.

Happines isn't the result, and nor is money.

If Your employers have expendable cash as you say, just ask them to buy a new head while the current one is on the warranty trip.

Regards
Sam

ohnoitsthebass · #7 11-13-2011, 12:09 AM

at tbird, yeah i know that, its a cheaper easyer fix at the moment to get the new tubes and make it work, after that i was going to replace tubes one by one until i could isolate the problem. and then figure out what the real problem is or may be. and no i have not seen the threads about tube warrantys, enlighten me please. personally im not a fan of the newer ampeg tube heads, they are made pretty crappy in compaison to the vintage ones, both in sound and in product. but we have one at one of my in house sound gigs because thats what alot of the big bands ask for/ or wont say no to. just need to do a quick fix for now and any info on anyone elses experience with this sort of issue with it would be helpful.
thanks

juggernaut1 · #8 11-13-2011, 07:21 AM

Mine started doing this yesterday. The amp almost new, low hours on it.

RickenBoogie · #9 11-13-2011, 08:31 AM

Quote:

Originally Posted by ohnoitsthebass

at tbird, yeah i know that, its a cheaper easyer fix at the moment to get the new tubes and make it work, after that i was going to replace tubes one by one until i could isolate the problem. and then figure out what the real problem is or may be. and no i have not seen the threads about tube warrantys, enlighten me please. personally im not a fan of the newer ampeg tube heads, they are made pretty crappy in compaison to the vintage ones, both in sound and in product. but we have one at one of my in house sound gigs because thats what alot of the big bands ask for/ or wont say no to. just need to do a quick fix for now and any info on anyone elses experience with this sort of issue with it would be helpful.
thanks

Unless you are an amp tech, and have ALL the necessary tools and testing equipment to diagnois the trouble, then you do in fact need to take the amp in to see someone who does-period. Swapping out a tube here or there will do NOTHING to actually correct the problem, and in fact, will only cost more $$ later to get the amp healthy again.

ohnoitsthebass · #10 11-13-2011, 01:19 PM

i do have the tools to do it and do know what im doing, so i will be takeing it entierly apart tomorrow and try and diagnose it to find if it was just a bad tube or if there was more to it that would cause it to blow.

BassmanPaul · #11 11-13-2011, 01:27 PM

Quote:

Originally Posted by ohnoitsthebass

i do have the tools to do it and do know what im doing, so i will be takeing it entierly apart tomorrow and try and diagnose it to find if it was just a bad tube or if there was more to it that would cause it to blow.

I'm worried! Not for the amp but for you! Seriously, I feel that if you did indeed know what you are doing you would just have repaired the amp. If I were in your place the last thing I would have done is place a post asking for other's experiences.

Take the amp to a tech - his bill will be so much less than your life is worth!!!

ohnoitsthebass · #12 11-13-2011, 03:13 PM

i only really wanted to know if anyone knew more about ampegs fault setting mode as in either it apsolutly ment that it was a tube or if it would go into that mood for other issues as well before i ripped the thing apart wich would save me some time and effort.

Jerrold Tiers · #13 11-13-2011, 05:45 PM

A fault indication can be a tube, which is what it is supposed to show.

It can also be the fault detection circuit misbehaving

Or it can be a bad connection or part associated with the tube but NOT actually BE the tube.

So, no, it isn't necessarily a slam-dunk tube problem.

But, if you DO replace a tube, and it DOES fix the problem, the chances of it having been a tube problem obviously go up.... Still could be something that kills a tube after a while, but those are more rare....

beans-on-toast · #14 11-13-2011, 06:00 PM

This DIVO dynamic bias system that Orange has available looks pretty promising. A review with some details was published in Guitarist Magazine.

It won't work with an SVT but it is a neat idea.

4StringShooter · #15 11-13-2011, 07:31 PM

Quote:

Originally Posted by ohnoitsthebass

one of the house gigs i mix at has a 6 month old ampeg svt classic head, the fault led on the front of the head is blinking obviously meaning that it has an issue. looking for someone who knows or as owned one of these heads, need to know if its the power tubes, or a more internal problem. lets hear your experience with these and what it could potentially be wrong with it.
thanks alot

I have since sold my SVT CL. When I had almost the same problem, I took it in. Tech tore the WHOLE amp down, and told me thet GROUND WIRES for the Powertubes were BAD...ALL OF THEM. He replaced them, installed all new powertubes, AND the pre-amp tube. It sounded absolutely new after this. ONLY a Tech can Bias the Amp. Those lights , and adjustment screws on the back are USELESS. DO NOT use them. Trust me, take it IN.
Powertubes were $270.00 Canadian (for ALL 6)
Preamp tube ( 12 ax7) was $27.00.
If they try to hose you more , you're getting RIPPED OFF.

Sherwood Music, Kitchener, Ontario, Canada is where I bought the tubes. Look for their website.They'll ship.

4StringShooter · #16 11-13-2011, 07:33 PM

Quote:

Originally Posted by beans-on-toast

This DIVO dynamic bias system that Orange has available looks pretty promising.

It won't work with an SVT but it is a neat idea.

Unless it shows you VOLTAGE to the tubes WHILE in operation, that Biasing system is PHONY. Voltage measurement is the ONLY way to Bias Tubes.

Jerrold Tiers · #17 11-13-2011, 09:38 PM

Quote:

Originally Posted by 4StringShooter

Unless it shows you VOLTAGE to the tubes WHILE in operation, that Biasing system is PHONY. Voltage measurement is the ONLY way to Bias Tubes.

I still don't know what they are doing....... I have a suspicion that you have to tell it what tube you have where, otherwise I have no clue how it would know you have a 6V6 vs a 6550..... although with enough data stored, it might find a match and ASSUME it has the right one.... I doubt that would work.

In any case, if you know the tube, you know the bias range, and probably can adjust to get it right. I can think of several ways to do it, any of which might be OK or might have problems if I think about them more.

Seems like you need the PLATE voltage to know if you are over-powering the tube on bias..... someone seems to have done a good bit of work.... but the thing appears to be still 'tech-centric"..... "have your tech set it up using the bias program...."

beans-on-toast · #18 11-13-2011, 09:58 PM

I added a link in my post above to a Review in Guitarist where there are more details describing how it works.

The tube plugs into as socket adaptor, the adaptor plugs into the amp. There are wires that go to the controller box. They must monitor a voltage across a cathode resistor installed in the adaptor. I assume that you have to tell the software which tube is in which socket.

I assume that a tech needs to set it up initially because there are a lot of options. For instance, how hot or cold do you want to run your tubes. I assume which tubes you want to run.

I haven't heard much of this since Orange announced it at NAMM last January. I wish a manual were available. Maybe they are still trying to get it out the door.

T-Bird · #19 11-13-2011, 10:42 PM

Hi

Quote:

Originally Posted by ohnoitsthebass

i only really wanted to know if anyone knew more about ampegs fault setting mode as in either it apsolutly ment that it was a tube or if it would go into that mood for other issues as well before i ripped the thing apart wich would save me some time and effort.

Mr Tiers sure does...

Quote:

Originally Posted by Jerrold Tiers

A fault indication can be a tube, which is what it is supposed to show.

It can also be the fault detection circuit misbehaving

Or it can be a bad connection or part associated with the tube but NOT actually BE the tube.

So, no, it isn't necessarily a slam-dunk tube problem.

But, if you DO replace a tube, and it DOES fix the problem, the chances of it having been a tube problem obviously go up.... Still could be something that kills a tube after a while, but those are more rare....

But as You can see, a positive diagnosis over the 'net is virtually impossible.

Tube amp diagnosis is pretty straight forward, less time to be saved with possible over-the-keyboard advices than it takes to type 'em. IME/IMHO anyway.

I still can't understand why the owner wants to void the warranty in hopes of "saving" a few measly bucks, something that'll probably bite him/her in the butt sooner or later.

And You as well, obviously.

If You dig in, and the amp fails again, who do you think they'll blame?

Regards
Sam

JimmyM · #20 11-13-2011, 10:51 PM

Quote:

Originally Posted by ohnoitsthebass

at tbird, yeah i know that, its a cheaper easyer fix at the moment to get the new tubes and make it work, after that i was going to replace tubes one by one until i could isolate the problem. and then figure out what the real problem is or may be. and no i have not seen the threads about tube warrantys, enlighten me please. personally im not a fan of the newer ampeg tube heads, they are made pretty crappy in compaison to the vintage ones, both in sound and in product.

I play rented SVT's all the time and I hear very little difference in any of them, whether made in the US or abroad. And the new ones work just fine. It's the tubes that are usually the problem, and there's not a whole lot you can do about that with new tube production being what it is.