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Ampeg SVT II Pro Needs More Headroom

#21
A few years back, I got into a power trio. We rehearsed in a really well insulated and acoustically quiet garage, and there were a lot of watts pumped out. I had to upgrade my amp fast so I drove down to the music store to pick up an SVT Classic and be done with it. I had a mid 70's double stack back in the day and I figured I would have tons of overkill bass volume available. Well, I worked with the volume and tone controls on the Classic and no matter what I just could not get enough usable volume out of it before my bass turned into a gigantic fuzz box. And this was pumping through some pretty substantial front end cabs. I didn't know what Ampeg had done to the SVT but it sure wasn't usable for my situation! I had it for a disappointing 45 minutes and took it back to the store where I then got a 4 Pro. That was a bit better but a couple of weeks later I added a used SVP 1600 and that gave me enough juice.

There's a lot of justifiable SVT tube love around, and if I didn't need (or want) as much clean bass volume as I do, I would get another tube SVT for sure. I'd still like to have one as part of my amp stable, but realistically, I'd need two at least.

You might not have a problem with your amp at all. You just might need more clean volume than it's capable of.
 
#22
I'm no expert but it does sound like the II is "distorting" faster than you want it to. It sounds like an amp with more power (Pro 4 etc.) might be what you really need.

I used to run the SVP preamp ( which I believe was the II or 4 preamp in a rack) with a 1600 watt power amp (Crest Audio) and I loved my tone. I could back the SVP gain way off and use the SVP master volume and the Crest volume to get me all the volume I could want. The Crest was so clean and loud that I had the tone it sounds like you're looking for.

After all isn't the Pro 2 actually designed to me that loud and gritty at the same time?
 
#23
Here's a thought ... I'd would try to get a 5751 preamp tube, and put that in the V1 position ( that usually it the tube nearest the input jack ), that tube has a little less gain, than a 12AX7 ... if your you want to fiddle around with some more tube rolling, then I'd would try swapping out the 3 tubes in the back, by the output tubes, those are your driver & inverter tubes, the 12AX7 is the inverter tube, make sure it is a balanced output, then I'd try to find a pair of Jan 6189W tubes ( these are the rugged/heavy-duty version of the 12AU7 and these are still somewhat inexpensive $10-$15 each ) and use those in place of the 2-12AU7's, then let the amp sit on stand-by for 20-45 minutes, make sure the amp is hooked up to a cabinet, then take the amp off stand by, turn the volume down, no instrument plugged in, and reset the bias, to where the green lites come on, I have done this to my SVT II Pro and have gotten a little cleaner sound, and I'm using some old 6550-R's, it could be the output tubes are contributing to the issue?, but who knows, some people like the EH 6550's, some don't, I haven't used them, so I can't really say, I have heard of some people using the KT-88's, to get away from the sound of the 6550's, I also own a Fender Bassman 300 Pro, and that amp stays cleaner at a louder sound level, than my SVT II Pro, but the SVTII Pro has that Ampeg vibe/sound when using a sealed cabinet ... I'm assuming the 4x10 your using is ported? ... could be the SVT II Pro, just doesn't like being connected to a ported cabinet ?
 
#24
SVT-IIpro is more wooly sounding than the older non-master volume SVTs, but I'm splitting hairs when I say that. Your amp should absolutely kill. Someone suggested that an SVT-4 pro will be louder. That's nonsense (no offense). I've used both amps. They're both crazy loud amps.

See if you can get your hands on an Ampeg 810 to A/B against your 410 to rule out the possibility that it's your speaker cab's efficiency or voicing that's giving you fits.

People on here will flame me for this, but I've always found that EH 6550s sound fuzzier and less punchy than my beloved Winged C brand. I couldn't stand the sound of my SVT-CL with EH tubes in it. The problem is that you don't have a set of Winged C's to try out and retubing on someone else's whim is expensive and ill-advised. Too bad you're not in my area. We could get together so you could hear the difference.

Lastly, try to find someone else's SVT-IIpro and listen to it. If it's vastly different, take yours to the doctor.
 
#26
I'm an idiot. I've been playing with a bad V3 tube this whole time. I switched them around and the one from V3 didn't light up at all in V1 and there was no sound coming through the preamp, leading me to believe I'd screwed something up. When I replaced V1, V2, and V3 (just to see if I could get it alive again), it came to life and sounds pretty darn good. Waay louder and cleaner than it had in the past.

As a side note, will KT88's give me even more clean loudness without overheating the thing?

Thanks for everyone's advice!
 
#27
In my experience these amps can't play clean at high volume. They aren't made for it. They always sound gritty. You also can't get the EQ flat. I really dislike them. They have a boxy congested tone.

I recently did some recording and the studio owner wanted me to use his SVT classic with a vintage cab. It sounded nice, but we had it on like 3, otherwise it got too farty and the cab started to bottom out.

He also had an Ashdown combo, and that was much louder through the same 8x10 cab than the SVT, and I think it sounded better too. But then I use a vintage Trace Elliot head, and the same guys designed the Ashdowns.
 
#28
ryankself said:
As a side note, will KT88's give me even more clean loudness without overheating the thing?

Thanks for everyone's advice!
Click to expand...

Don't do it. It do really sound good. But the SVT is not designed for KT88's. If you push the amp the KT88s will draw too hard and could start pop'ing **** in the amp.

I really wanted to retube my SVT 2 pro with KT88's but my repair guys (who I really trust) strongly recommended against them. It is a reliability issue for the amp.

But they did say as long as you don't push the SVT, KT88's will work. But, I push my SVT 2 pro... so I got some winged C 6550s and I'm completely happy.

(this is what I have been told, so correct me if I'm wrong)
 
#30
What is your 'tube drive' knob set on? I've found that the higher you turn this up, the more bass gets sucked out and mids/ distortion come in with a vengence. Anytime I turn this up(which is usually around 10/11 o' clock, I have to adjust my eq settings to compensate. Just some food for thought.
 

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