Potential Problem With EBS TD650 Head

Modulus1906 · #1 06-25-2010, 12:32 PM

Hey fellas, just need some advice. I have an EBS TD650 head that is a couple months old, and I've noticed a slight sizzling sound that I hear when I'm playing usually with the gain set to about the 10:30 - 11:00 o'clock position. This sound is "frequently intermittent" but tends to disappear completely when I set the gain to 12:00 and higher. Also, the sound only occurs when I'm playing.

The sizzling sounds reminds me of bacon frying (sounds like static) but it does not affect the tone...it just seems to ride on top of the tone. I took the amp back to the dealer shortly after I bought it but we could not replicate the sound so I eventually left "satisfied". I thought that it wouldn't be that big of a deal to just bump the gain up to 12:00 and never have to deal with whatever random mystery might be causing the static. Then I got to thinking that I should be able to use the gain as I choose without having to settle. The amp has a tube preamp stage. Any ideas what may be causing this intermittent sound? Could it be that one of the tubes needs replacing? I want to have whatever it is fixed if there is a problem, but I'm just concerned that I've never be able to duplicate the problem while the dealer is looking at it (you know how that goes). By the way, it was making this sound at the dealer before I bought it, but I just though it had something to do with the amp being surrounded by a bunch of other electronics, etc. Any ideas what might be causing this or what my next step should be? Could it be the cabinet (Heritage Ampeg SVT410-HLF)? Thanks

RickenBoogie · #2 06-25-2010, 05:51 PM

Try changing the tubes out. If that does it, you're done. If it doesn't, I'd take it back.

Modulus1906 · #3 06-26-2010, 07:12 AM

Any more ideas?

fretno · #4 06-26-2010, 07:36 AM

could it be as simple as a dirty pot , try sweeping the pot fully left to right and back a few times to "clean it" or even some pot cleaner like Caig Deoxit . I would'nt think it was the tube but it could be and I would also suggest you pop one in to find out , it is switchable so what happens on the SS side of the pre ? Also that amp has a "drive" and as the gain comes up you may be interpreting the overdrive as bacon cooking especially if you have a tweeter as it will be clear . It's odd that it won't do it for the dealer though .

craig.p · #5 06-26-2010, 07:56 AM

I'm with RB. I think you should simply take the amp back for a refund. If that's not possible, then ask for a replacement or at least some serious hand-holding WRT warranty work.

When you crank the gain up, are you lowering something else to achieve the same volume you had when the gain was at 10 o'clock, or did you mean you're cranking the gain up (and doing only that) and therefore getting more volume from the amp?

Does this happen when the amp is cold, or only after the amp has come up to temp, or always?

Does it happen with the amp oriented differently -- standing on its side for example? (Don't block air flow when you do this.)

Those are some of the things you can try to get some failure consistency and predictability so you can demonstrate it successfully in the store. Remember, always start with identical baselines. KEEP DETAILED NOTES FOR EACH TEST CASE.

I could take a couple of SWAGs regarding why your amp is doing what it is and the possible scenarios that brought it on, but what's the point, really. Broke is broke. There's little to no value in figuring out the whys of it in light of the fact that you have a warranty and maybe even a refund option. If this were an out-of-warranty unit it'd be another matter.

Modulus1906 · #6 06-26-2010, 07:39 PM

Quote:

Originally Posted by craig.p

I'm with RB. I think you should simply take the amp back for a refund. If that's not possible, then ask for a replacement or at least some serious hand-holding WRT warranty work.

When you crank the gain up, are you lowering something else to achieve the same volume you had when the gain was at 10 o'clock, or did you mean you're cranking the gain up (and doing only that) and therefore getting more volume from the amp?

Does this happen when the amp is cold, or only after the amp has come up to temp, or always?

Does it happen with the amp oriented differently -- standing on its side for example? (Don't block air flow when you do this.)

Those are some of the things you can try to get some failure consistency and predictability so you can demonstrate it successfully in the store. Remember, always start with identical baselines. KEEP DETAILED NOTES FOR EACH TEST CASE.

I could take a couple of SWAGs regarding why your amp is doing what it is and the possible scenarios that brought it on, but what's the point, really. Broke is broke. There's little to no value in figuring out the whys of it in light of the fact that you have a warranty and maybe even a refund option. If this were an out-of-warranty unit it'd be another matter.

Thanks..really great points. When I crank the gain, I'm just getting more volume since I don't make an compensating adjustments. Funny that the amp never seems to clip even when I set the gain as high as 2:30. Of all of your questions, the only one I can speak to is that the static seems to kick in after the amp has been on for 5 minutes or so, but it is so inconsistent.

craig.p · #7 06-26-2010, 08:15 PM

Once the unit's warm enough so the noise appears, can you make the noise occur by (slightly!) bumping the amp around? If so, that would indicate a cracked etch or a loose tube or a bad tube or even a loose tube socket.

If not, could be anything from a loose internal connector to wrongly-biased output transistors. Again, all tech/warranty work.

Does the amp have a power-amp-in input, and if so, can you drive it with an MP3 player (bass-heavy content) to see if the problem appears? Then do the same right into the instrument input (drop the player volume way down of course). At least that might help narrow things down to either the preamp or the power amp.

You might also want to record the noises you're getting when you play, and then burn a CD of it and bring it with you to the shop (or send it along with the amp if you're shipping it).

You need do no further testing with the amp cold. Your new baseline is "amp warm."