SVT-2 Pro

[jastacey]

I just acquired a Ampeg SVT-2 Pro, got a deal on the local Craigslist for $500 ..... a couple of quick questions from the experts, when trying to date the amp, with the Ampeg Book, seems I have too many digits ...the SN # is T2PROJ1ooXX , the next question, is I plan on mounting it in a 4 space rack-case, should I drill vent holes for the fan? .... how accurate is the bias lights system, also any suggestions for the driver & phase tubes, and lastly, what is the suggestion of power tubes , I've only had experience with the 6550's in my Bassman 300 and the first set was Sovtek 6550w, they were O.K. but I loaded a set of winged "C" in it and I like them also ... it's going to interesting to do a long term comparison between the two

[JimmyM]

man, you ask a lot of questions for a guy from houston!

anyway, great score! i'll try to answer what i know:

serial: start after the t2pro, then it should make sense.

racking: looks like it vents from the back, so it should be fine without adding any extra holes as long as you keep the back off while using it

bias lights: if replacing power tubes, i would probably go ahead and try to do a bias with the lights because i'm cheap, but there are bias points for a tech to do it more accurately than the lights.

t00bz: if it's working, i'd just leave whatever's in there. for pre/driver tubes, i like using nos tubes, although jj's do pretty well. for power tubes, winged c's seem to be the favorite in svt's. i would favor nos tubes for power if they weren't so insanely expensive.

[Jerrold Tiers]

That number should be January '97

[jastacey]

Thanks for the dating .... Jerrold, I was looking at the schematic and noticed that there are no test points for the SVT-2 pro, like the early versions, are the led's that accurate?

[Jonyak]

There was a date on a sticker on the inside bottom cover of my 2 pro.

as for the LED's I don't see why they would put them there if they were not accurate enough to be used to bias the amp.

$500 is a great deal, I paid 1100$ for my 93.

[Jerrold Tiers]

Originally Posted by Jonyak

There was a date on a sticker on the inside bottom cover of my 2 pro.

as for the LED's I don't see why they would put them there if they were not accurate enough to be used to bias the amp.

$500 is a great deal, I paid 1100$ for my 93.

they are "pretty good", however a meter is still the best way. But if you bust a tube or two when on the road or at the gig, the LEDs will get you close enough to keep the smoke in.

[jastacey]

Here's an update, I got a chance to run the amp through a 8x10 SVT Cabinet, and it really can get loud, and it has that gritty Ampeg tone, but it's a noisy amp ( kinda like a low-grade white noise/hiss, it's somewhat louder than my V4-B, but the V4-B has a Hum Balance pot control ), my Bassman 300 is much quieter, I've noticed that there is no hum balance control, looks like the preamp/driver tubes my be causing the issue, as they appear to be OEM to the amp, any suggestions as to what brand of driver tubes for the driver section, and what combination of tubes that sounds good for the preamp section? I realize that all suggestions are one's preferance and what sounds good to one, may sound somewhat iffy to another, but what I'm looking for is a consensus of what folks have done to there amps

[Alexander]

There are vents on the side as well - I think I read something somewhere saying you needed to leave 1RU above and below the amp for ventilation also. The amp gets quite hot.

When the amp is running properly, there shouldn't be any hum. I'm no tech, but any time I hear hum, it has been a problem with the tubes. You can adjust bias on the back until both green lights are on and then fine tune the hum out. If you can't (or this doesn't hold), you should get it checked out.

[sapienerabass]

Congrats on the purchase, I use the same SLM era SVT2 Pro that I bought new in 96. I agree it is a noisy amp, my "simple" solution was to buy a boss noise supressor pedal and that solved the issue for me. Have you tried the ground lift switch? Apparantly that can resolve noise issues from either suspect lighting or PA wiring.

As for tubes if they work....then they work! I got duped into changing my tubes when the amp was about 12 months old (pre TB forums!!) I'm still kicking myself!! I had fender 6550s installed as my factory tubes were "sounding dull!". The damn tech kept my original tubes as I foolishly thought they were "dead/dull". I'm still running the amp with those fender 6550s thirteen years later!!

[jastacey]

Thanks for the ground lift switch tip, I'll give it a try next week ... My plan is to do the tube change-out in sections, preamp section, driver section, one tube at a time till the noise is gone ...seems that this amp breaks-up rather soon ... been running the master at 2-3 o'clock and using the preamp gain as the volume control, tried using the master at 11-12 o'clock and it just didn't sound as good ... IMHO

[guitarjam6]

I just had the chance to play this head through a 610HLF cab since it was backlined at a gig. I spent about 20 minutes tweaking it before playing, and found alot of good punchy tones with my Ibanez SR900 and Keeley Compressor...Super tight sound and headroom for days. Good find.

[jastacey]

Here's an update ... I replaced all the Sovtek 12ax7 tubes with new JJ 12ax7 and it really cleaned up the noise, I left the 12au7's in since they were 6189W Phillips ECG tubes and they tested good on my Heathkit TC-2 tester, they buried the needle in the good section of the scale .... the power tubes tested good, they are Groove Tubes 6550-R ... it's interesting on how the drive knob works, it gets things pretty crunchy ... seems I have kinda poor luck with the Sovtek 12ax7 tubes !!!

[JimmyM]

you're not the first to say that about the sovteks. personally, i've never had a problem with them, but it seems like lots of folks have on here.