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Ampeg SVT-II appreciation thread

#301
NickyBass said:
Quick question....Can I use JJ ECC82 and JJ ECC83 tubes as a replacement for the 12UA7 and 12AX7 preamp tubes? I have a few of each already and I wanted to expieriment with different tubes to narrow down my static issues. Thanks for any help. BTW, this is a great thread and a great resource for SVT II's.
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12AX7 and ECC83 are the same, as are 12AU7 and ECC82

12AX7 tends to be the american designation, with ECC83 the more common designation in the EU (historically at least).


mattmanbass said:
im stoked about your fan page Mohawk, keep us updated on your progress.
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I'll keep info posted in here.

Won't contain huge amounts of info, but will have the manual for download, aswell as the technical schematics etc if im ok to post them (will have to check with Timv). Will contain a gallery (all you guys are free of course to submit pics when its up).

Some links to bands etc (you guys again) using them, MP3 samples with tracks which have the SVT-II used for recording etc.

Just a place for knowledge of this (near) vintage amp :)
 
#302
Hi folks,

I too have an SVT-II with the grill in the back covering the tubes. What the next number in line? I understand this one to be one of the newer ones. The boards had a -91 date on them. So the amp may be a 91 or 92 vintage. I hope you folks can help me here.

The Problem:

Background: I got this this used from the first owner he had not played it in many years (~3). It sounded very good with his Ampeg fridge. When I brought it home I checked all the tubes on the tube tester and set the bias. There were some worn tubes but nothing out of the ordinary.

Problem: This is where I am stuck. I put a matched sextet of power tubes in there and biased it properly with a DMM. It sounds wonderful with on exception. With all controls at noon, eq out, and no buttons depressed, I get an annoying hi-frequency clipping or crackle in my tweeter (Berg HT 322). I know a little about amps but this one is out of my league. It sounds like a dry cap or a bad solder joint somewhere. The happens only when the volume is 1/2 or louder. I have had SVTIIs before and this is the first one thats doing this. I know it is not normal and that I am playing within reasonable limits.


The Question: Does anyone know what could be wrong and how to fix it or more so; can anyone recommend a knowledgeable tech in the Los Angeles area that knows the ins and outs of this amp to bring it up to spec with the factory mods and all the corrections it may need?


Your help is much appreciated.

Regards,

Alltube
 
#304
alltube said:
It sounded very good with his Ampeg fridge.

I get an annoying hi-frequency clipping or crackle in my tweeter (Berg HT 322). only when the volume is 1/2 or louder.
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My SVT-II at similar knob settings produces a very loud saturated tone that usually results in annoying hi-frequency clipping through many tweeters/horns too. I'd bet your issue can be corrected by simply turning your tweet off. (or correctly disconnected if necessary)
 
#305
Thanks for the amp tech ref.

Well, If you tell me that the hi-freq distortion/clipping is normal it may be true as these beasts were built around non-tweeter cabs and it seems that part of the svt sound is a distortion somewhere in the mid range that is somehow pleasing and makes you stand out in the mix.

One thing to note: I played it some more tonight and it seems that this unpleasant hi-freq distortion that I am talking about is diminishing. Could it be caps that are being exercised and are starting to do their job better? This is strange. I will keep you all posted. I have other tube amps (DB728 and a Mesa 400+) that does not do this on the same cab and cables.
 
#308
Ok folks,

I said i would keep you posted and here it is:

Until the amp techs can chime in:

I used a preamp in the PWR AMP IN jack and had the same tweeter distortion. I also changed out to and AMCE B2 and had the same tweeter distortion.

So: It seems to be coming from the Power Board, and not the head's preamp. At least I have localized the source some. Maybe I have a bum set of power tubes; I'll swap them out later and see how that goes.

One things for sure though, this amp has GUTS.

It's trandfromers are bigger than that of a Mesa 400+ and you feel it in the lows and low mids.

Will keep you posted.
 
#309
I'd like to jump into the party. I have had an SVT-II for about 4 years now - simply the best amp I've ever heard, and I really did want to like that Mesa 400+... The odd thing about mine is that it has no serial number. I bought it off a guy on Ebay, and the serial number had been scratched off. There was a seal from the City of Los Angeles Police Department on the back, but that has since faded. This thing must have wonderful stories to tell... I've currently got it driving an Aguilar GS-410. There is nothing at all quite like it.
 
#310
Inverness said:
I'd like to jump into the party. I have had an SVT-II for about 4 years now - simply the best amp I've ever heard, and I really did want to like that Mesa 400+... The odd thing about mine is that it has no serial number. I bought it off a guy on Ebay, and the serial number had been scratched off. There was a seal from the City of Los Angeles Police Department on the back, but that has since faded. This thing must have wonderful stories to tell... I've currently got it driving an Aguilar GS-410. There is nothing at all quite like it.
Click to expand...

Oooooooo eeeeerrrrr!!!!!:ninja:
 
#311
alltube said:
Ok folks,

I said i would keep you posted and here it is:

Until the amp techs can chime in:

I used a preamp in the PWR AMP IN jack and had the same tweeter distortion. I also changed out to and AMCE B2 and had the same tweeter distortion.

So: It seems to be coming from the Power Board, and not the head's preamp. At least I have localized the source some. Maybe I have a bum set of power tubes; I'll swap them out later and see how that goes.

One things for sure though, this amp has GUTS.

It's trandfromers are bigger than that of a Mesa 400+ and you feel it in the lows and low mids.

Will keep you posted.
Click to expand...
Hi there, I replied to your other thread and dont know if you got back to it or not.

Have you tried putting the original tubes it came with back in?
 
#312
Well,

I could not wait. I pulled the power board and removed some electrolytic capacitors and tested them out. I found a dead 180mF 450V cap that was reading OL (dead); The rest seem fine but i'll have an order in with Digikey soon for all of them.

Regards,
 
#313
I am not trying to derail this post but would like to hear from some of you that had a chance to play the SVT-II and the SVT-II Pro. I would like to hear all of the simularities and differences. I love that SVT tone and would love to have a SVT-VR or an orig. model. But I think I could get a good deal on the SVT-Pro from a local player. SVT-II Pros are much more plentiful than the SVT-II.

PS. I have done searches and read reviews but I am wanting more opinions.

Thanks
 
#316
I have an SVT II made in 1989, I bought it in 1991, so I know its' tone and capabilities pretty well by now. I've tried the SVT II Pro a couple of times, but I've never done a side by side comparison. IMO the Pro sounded harder and not as warm, but it was brand new; it isn't really fair to compare a new amp and one that's been used for years, but the difference was clear. The Pro does have some improvements over the older SVT II, but in the tone department I think SVT II is better. My amp is a fairly early model, so it doesn't have the back panel metal grille for tube protection. Another bummer: no bal out level control (the difference between pre EQ and post EQ signal levels is huge) and the fuses are hidden inside the amp (on the later versions the fuse sockets are easily accessible on the back panel).
 
#318
The fixed cable isn't a problem for me as my SVT II came with the wooden Ampeg head cabinet, at the rear there's a space between the cabinet and the amp that's useful for storing the cable. In the other space I store my speaker cable and the power cable for the external 230/110V transformer (my amp was made for domestic US market only, so I have to use an external transformer; don't even know if Ampeg made any export 230V models back then).
 
#320
Petethebassman said:
The fixed cable isn't a problem for me as my SVT II came with the wooden Ampeg head cabinet, at the rear there's a space between the cabinet and the amp that's useful for storing the cable. In the other space I store my speaker cable and the power cable for the external 230/110V transformer (my amp was made for domestic US market only, so I have to use an external transformer; don't even know if Ampeg made any export 230V models back then).
Click to expand...

Ah right, I always quite fancied one of those ampeg head cabinets. As long as I have had mine, it's been in a 4U ata case, there was usually enough space to bundle in the cable, but the plug remained exposed. (and could work its way out and flail about).

Take it to a tech, and have him look at it. My SVT-II is also an '89 model. And printed on the back it says "110v". However, on looking inside, the wires on the transformer taps have been moved around. Most (if not all) of these can be wired to run at 230v (well, maybe 240 or 220? im not sure). Wouldnt take too long on a tech bench and would mean you wouldnt need to worry about the external transformer :)
 

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