SVT2PRO Tubes not biased after being serviced?

slapstick13 · #1 12-20-2010, 07:26 AM

So I just got my svt 2 pro back from being serviced at the most reputable shop around. Everyone I know in a band takes their gear to this place. I got all new power tubes(6) installed. I got to my practice space, plugged her into my 810 cab and let the amp warm up for a half hour and flicked the standyby switch. I checked the bias lights on the back and according to the manual from ampeg both lights should be GREEN ONLY. Ive set the bias myself in the past and its very simple to get both lights green.

HOWEVER, both lights show RED and GREEN. Did the guy forget to set the bias? I was nervous to really play the amp, but I played for a little bit and everything sounded fine. Im just nervous about the tubes burning out prematurly. Should I call the tech guy? WHat do I do????

ajunea3 · #2 12-20-2010, 07:33 AM

I'd just set the bias myself and forget about it. As you said, you've done it once before.

slapstick13 · #3 12-20-2010, 07:37 AM

I know, thats what I told myself, but I payed a lot of money for this service and if I didnt check the bias lights Id be right back in the shop dishing out more money ya know. How could he have skipped this step? I could have changed tubes myself! I just figured for my first retube I should have it done by a tech. Is it possible that he has it set for slightly more current running into the tubes for better sound?

JimmyM · #4 12-20-2010, 08:27 AM

yes it is possible. the tech can do a much more pinpointed bias than you can with the lights. but if it bothers you to have those lights not be green, reset the bias yourself.

slapstick13 · #5 12-20-2010, 08:33 AM

I was waiting for jimmy to chime in! Its not that it 'bothers' me that both red and green are on. I just want to make sure everything is properly set before I start blasting the amp at practice.

blastjv · #6 12-20-2010, 08:33 AM

Just call and ask him. Like Jimmy said, maybe he biased using a meter instead of the LED's (which is what you'd be paying a tech to do, otherwise why not just do it yourself) It is possible that the 'correct' bias when done with a meter is off from what the LED's tell you...if that's the case, the rest of us who biased using the LED's should be more worried than you.....

-JV

JimmyM · #7 12-20-2010, 08:43 AM

ya, just call him. i'll bet that's exactly what he tells you.

slapstick13 · #8 12-20-2010, 09:27 AM

Tru, good idea ill call him today. I didnt realize hed be doing biasing beyond the controls in the rear panel. Thanks for bringing my anxiety down!

jackcheez · #9 12-20-2010, 09:54 AM

I've done the bias on my Ampeg with the lights. Unless they are malfunctioning for some reason they are pretty good. They should show green.

Something that just about anyone should be able to notice is there is a small "range" of green when you do this. There is a slight hum that you can hear. It will get a little louder as you move towards over or under bias but are still in the green range.

Jerrold Tiers · #10 12-20-2010, 09:37 PM

yeah... not perfect, but usually pretty good..... Ask the tech.

If he blows you off with "those lights are always wrong", then be suspicions..... But if he says "the lights were reading high, its biased to the correct voltage" then maybe he's OK and did it right.

slapstick13 · #11 12-21-2010, 10:03 AM

So I called my tech yesterday. He said the lights are more of a guide and its made so that the average user can do the bias themselves. He hooked it up to his meter gadget thing and the readings were fine where the bias was set. So he said theres no need to worry!

HOWEVER, I am totally unsatisfied with the sound after playing a 4 hour practice last night. It honestly sounds like crap to me. It sounds too clean, sterile, almost no breakup with the amp cranked and sort of muddy. VERY un SVT sounding to me. He used 'valve art 6550' power tubes. I can't find much info on these, but it doesn't sound nearly as ballzy and meaty as it did before I took it in to my tech. Is this because they are crappy tubes? Ive been contemplating selling the amp because it IS in 'perfect working condidtion'. I just cant imagine ever paying another $300 and being unsatisfied with the amp. And Im not about to buy another set of tubes. Damn money pit! I A/B'ed the amp with an old peavey 400 bass amp(both playing out of 810e), and the ampeg was honestly not THAT MUCH better sounding. Definatly not $1800 or so better thats for sure. What do I do!!?! besides cry

JimmyM · #12 12-21-2010, 10:21 AM

sounds like it was biased cold. that gives you longer tube life and a cleaner sound, and maybe he thought that would be more desirable to you. might also explain why the lights aren't quite matching up.

slapstick13 · #13 12-21-2010, 10:27 AM

Actually, according to the ampeg manual, red and green lit at same time(which is what mine is) means more current running through to tubes. Supposed to sound 'richer and bigger sounding' but decreases life of the tubes. In reality it sounds the opposite.

JimmyM · #14 12-21-2010, 10:30 AM

well the lights are probably moot at this point since you said it came back with ka-flooey lights.

MAMMOTHvolume · #15 12-21-2010, 10:38 AM

Quote:

Originally Posted by slapstick13

So I called my tech yesterday. He said the lights are more of a guide and its made so that the average user can do the bias themselves. He hooked it up to his meter gadget thing and the readings were fine where the bias was set. So he said theres no need to worry!

HOWEVER, I am totally unsatisfied with the sound after playing a 4 hour practice last night. It honestly sounds like crap to me. It sounds too clean, sterile, almost no breakup with the amp cranked and sort of muddy. VERY un SVT sounding to me. He used 'valve art 6550' power tubes. I can't find much info on these, but it doesn't sound nearly as ballzy and meaty as it did before I took it in to my tech. Is this because they are crappy tubes? Ive been contemplating selling the amp because it IS in 'perfect working condidtion'. I just cant imagine ever paying another $300 and being unsatisfied with the amp. And Im not about to buy another set of tubes. Damn money pit! I A/B'ed the amp with an old peavey 400 bass amp(both playing out of 810e), and the ampeg was honestly not THAT MUCH better sounding. Definatly not $1800 or so better thats for sure. What do I do!!?! besides cry

those chinese ones are good they'll do more power so you'll have to crank it a bit more. Also have you tried diming the preamp gain a bit more?

slapstick13 · #16 12-21-2010, 01:12 PM

I did try to crank it and it just gets very boomy. I had the gain at noon, master at about 2:00. That should be loud no matter what tubes are in there I would think. Ill give it a shot at band practice tonight, maybe try really cranking the gain to 3:00 or so. Im just amazing at how different 'my favorite amp ever' sounds after a retube. Its like the amp lost its goooey tubey soul =*(. The magical harmonic overtones/ 3D feel is gone almost completely.