Anybody have any info on the all tube 1980's Ampeg SVT blackface???

[Bionic-Joe]

Just played one today at GC. LOUDER and More versatile than my Hiwatt!!! Anybody know anything about these badass black face/black grill 1980's SVT's?? They have the white rocker switches just like the link below I shared:

http://www.ebay.com/itm/321160589305?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

[Psycho Bass Guy]

They're are two different types that can look like that. The oldest is the MTI made SVT, which was made in Japan. Because they have smaller transformers, they put out slightly less power (about 280 watts) than other vintage SVT's and lots of people dog them and say they're poor quality. Lots of people are very wrong. Wattage aside, MTI SVT's are generally works of electronic art, with very expensive caps, ceramic heat collar standoffs for all the major resistors and much thicker board traces. The ONLY negative about their construction is that they lack the shock isolated chassis feet of other vintage SVT's, but they're easily replaced (I did on mine, same feet as the B-15 mounts with, BTW) or you can just put towels or foam underneath.

The other possibility is that is one of the first-run models made when St. Louis Music bought Ampeg from MTI. They were a limited run of 500, made in St. Louis to vintage spec and wattage excepting some minor preamp revisions to replace 12DW7's with 12AX7's. They all had a brass plaque on the back grille with their serial number.

I'll need more info to tell you which you played through. If you look on the back of the amp at the bottom right on the chassis, it will say where it was made.

[Bionic-Joe]

The one I played didn't say where it was made. But the serial number is 222496

[gearHed289]

If the Ampeg plate is on the wrong side (the right), it's likely an MTI. Those SLM limited run models were nice. I had an MTI for a while. Quick tangent - My first SVT was a '72. Loved it, but at some point around '92, for some reason, I decided I should have an SWR, and I sold it to Paul Barker from Ministry. When I got the SWR home and plugged into my 810, I was immediately disappointed.  Barker, of course, wouldn't sell the '72 back to me, so I went Ampeg hunting. This was back before the internet, so it was all the "Tradin' Times" paper. Picked up a couple of V-4B heads for super cheap. Then I found the MTI SVT. It seemed different than my old one. A little brittle or something. Eventually, I lucked out and found a guy willing to trade straight up a '74 SVT for my SWR. THAT was a no brainer for me! I also made him an offer on an 810 he had sitting there, and got a deal on that. Cause, ya know, you gotta have TWO of those things.  Sold the MTI and one of the V-4s, and I still have that '74. Recently sold the other V-4 as well.

[lowend1]

The brittle sound may have had something to do with the power tubes. The MTI heads, IIRC had GE 6550s, generally regarded to be "harder" sounding than the TungSol 6550. My '72 has the original Magnavox branded TungSols, and they ain't nothin' but warm.

[Psycho Bass Guy]

The brittle sound could have been a bias or power tube mismatch issue or even a microphonic preamp tube: no shock isolation on MTI's.  They also used 12AX7's in place of 12DW7's, and a 12DW7 has a much higher current output, so it will sound beefier and provide more current (low end) to drive the power section. If you had a bunch of 90's Chinese 12AX7's in there, that could also be it. They're ALL icepick-in-the-ear toned.

Once the preamps are 12DW7, there is no appreciable tonal difference between my MTI and any of my other SVT's. SVT's are like Chevy big blocks: they'll take tons of abuse and run nearly forever, but once you've experienced one dialed in properly and like it, you're ruined. GE 6550A's put out more power than the old Tungsols, but aside from having a very slight lift and more punch in the upper mids from better peak power, aren't going to make an SVT sound substantially different. Magnavox, by far the largest producer of the SVT, shipped them with both Tungsol and GE output tubes bearing their logo. The only output tubes I've ever had to have a pronounced tonal effect in the SVT are 90's Chinese KT88's (and those same KT88's rebranded as KT100's), which tend to be darker and more murky tonally, but even that is just a mild coloration.

Baz, serial numbers with Ampeg are generally meaningless. Got pics?

[Bionic-Joe]

No, Not yet, but it is the dame as the one from the Ebay link I listed.  $900.00  It's listed on the Guitar Center website in Villa Park, Illinois. It has the logo on the right and half of it is broken off. The amp on 1 sounded fantastic!...on 2 it was shaking the whole GC!!!!
The Bad SVT I ever heard was a solid state one. Never heard a bad Tube SVT.
  The right rear only had the 222496 Serial number, not where it was made or by who.

[lowend1]

IIRC, the skunkworks SVT have a head casing like the originals (angled in at the top), whereas the MTI has a squared off box that is cut in at the top front edge.

[Bionic-Joe]

I guess this is the MTI type...I may...MAY bid on the blue line SVT on Ebay...the one that's in Ann Arbor, Michigan...

[Psycho Bass Guy]

No, Not yet, but it is the dame as the one from the Ebay link I listed.  $900.00  It's listed on the Guitar Center website in Villa Park, Illinois. It has the logo on the right and half of it is broken off. The amp on 1 sounded fantastic!...on 2 it was shaking the whole GC!!!!

Odds are that it is an MTI, BUT the modular nature of the SVT means that there are tons of parted-together examples out there, some even came that way from the factory with mid-70's SVT's having Linden, NJ (pre Magnavox) preamp and power circuit boards. I have a '76 SVT that is bone stock but has a power board from '69. Grille logo locations do differ with origin, but those grilles are easily swapped, too. The knobs and faceplate on the eBay auction are SLM limited run, but the headcase and back grille are MTI and the chassis looks like SLM (hard to tell with it being so out of focus). Since the preamp section swaps with a few screws and a molex connector, there are quite a few options as to what circuit is actually happening. JUST Magnavox had over TEN circuit revisions to the SVT, some not even published in tech notes but common knowledge among Ampeg techs. Here's a surefire "tell" for the power section: what color are the large visible filter caps on the bottom near the power tubes and can you read the brand?

[Bionic-Joe]

I couldn't see anything on it. It was at Guitar Center in Villa Park, Illinois and I only played it for about 5 minutes.... But it's just like the one in the Ebay auction I posted.