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Ampeg SVT-II appreciation thread

#162
timv said:
Those extender things are just current monitoring sockets I made up myself. They were oriented to work for mesa's but seem to go the right direction for most amps I work on.
Anderbass's SVT II had a few of the problems that I have seen on these amps that are fairly easy to repair and modify so they aren't issues anymore. They used plug in connectors on some of the important signal and power lines that aren't exactly up to the challenge, his was the 3rd SVT II I've seen taht had issues with this. I removed the connector pins and just hard wired the wires to the circuit board. I left enough slack so the boards can still be removed. I made sure all of the updates were done, most were but a couple weren't done by whoever was in it before. Also, a plate resistor blew earlier (one of the updates gets rid of these resistors, you replace them with ferrite beads) and blew out part of the trace, this was repaired but the previous tech didn't check other parts and I found 3 blown diodes on the same power amp side, the amp was working but was biased cold and unbalanced. I rearranged the tubes to get better sets and replaced two that tested bad on my hickok 600a.
Originally I got around 250 watts clean out but after the tube swap I got 300 at various frequencies.
The schematic packet I scanned and sent to him was purchased form ampeg a few years ago, not sure if it is available anymore with the whole move but I did scan it the best I could. Some of the pages are 11x17 and my scanner only went to 11x8 1/2 so I had to scan left and right seperately and then reattach them.
Anyway........ enjoy the schematics and updates.
Click to expand...

HI

Those current monitoring sockets are a really nice idea. Good article,too. Are those "ferrite beads" actually coils?
 
#163
Are you not going to put that beastie in a case Rod?????

I've got mine in a 4 space Gator that I had laying around but I'm trying to find a 6U Road Ready for it (free space & My Rack Tuner).. What the hell, It already weighs a ton, why not a ton and a half? That's what trolleys are for and cuts down risk of theft!!!!

:-)

D
 
#164
timv said:
Those extender things are just current monitoring sockets I made up myself. They were oriented to work for mesa's but seem to go the right direction for most amps I work on.
Anderbass's SVT II had a few of the problems that I have seen on these amps that are fairly easy to repair and modify so they aren't issues anymore. They used plug in connectors on some of the important signal and power lines that aren't exactly up to the challenge, his was the 3rd SVT II I've seen taht had issues with this. I removed the connector pins and just hard wired the wires to the circuit board. I left enough slack so the boards can still be removed. I made sure all of the updates were done, most were but a couple weren't done by whoever was in it before. Also, a plate resistor blew earlier (one of the updates gets rid of these resistors, you replace them with ferrite beads) and blew out part of the trace, this was repaired but the previous tech didn't check other parts and I found 3 blown diodes on the same power amp side, the amp was working but was biased cold and unbalanced. I rearranged the tubes to get better sets and replaced two that tested bad on my hickok 600a.
Originally I got around 250 watts clean out but after the tube swap I got 300 at various frequencies.
The schematic packet I scanned and sent to him was purchased form ampeg a few years ago, not sure if it is available anymore with the whole move but I did scan it the best I could. Some of the pages are 11x17 and my scanner only went to 11x8 1/2 so I had to scan left and right seperately and then reattach them.
Anyway........ enjoy the schematics and updates.
Click to expand...

Alright... thanks for explaining the repairs Tim.

I'll bet there's quite a few other working-SVT-II's around that haven't had any of those factory updates preformed, and currently have (or will have) the same plug problems mine developed.
 
#165
Danm said:
Are you not going to put that beastie in a case Rod?????

I've got mine in a 4 space Gator that I had laying around but I'm trying to find a 6U Road Ready for it (free space & My Rack Tuner).. What the hell, It already weighs a ton, why not a ton and a half? That's what trolleys are for and cuts down risk of theft!!!!

:-)

D
Click to expand...

Yeah.... I'm currently either waiting for a mate to decide whether or not he'll build me one, or negotiating a bought one. trying to get one of the 'short' ones- about 14" deep as opposed to the regular 18" deep ones that'll look like it's gonna fall of the back of the NV610:spit:
Have a few I'm lookin at.....just have to decide!
It's nice having it this small tho!! :p It's SO easy to lift & move like it is, but U R right, & I don't wanna go breaking any knobs etc...
Will keep y'all posted.
I'm STILL dumbfounded on HOW ANDERBASS managed to get over to my house, photo my rig, get back to USA & post the pics on here tho! :eek::help:
 
#166
timv said:
Those extender things are just current monitoring sockets I made up myself. They were oriented to work for mesa's but seem to go the right direction for most amps I work on.
Anderbass's SVT II had a few of the problems that I have seen on these amps that are fairly easy to repair and modify so they aren't issues anymore. They used plug in connectors on some of the important signal and power lines that aren't exactly up to the challenge, his was the 3rd SVT II I've seen taht had issues with this. I removed the connector pins and just hard wired the wires to the circuit board. I left enough slack so the boards can still be removed. I made sure all of the updates were done, most were but a couple weren't done by whoever was in it before. Also, a plate resistor blew earlier (one of the updates gets rid of these resistors, you replace them with ferrite beads) and blew out part of the trace, this was repaired but the previous tech didn't check other parts and I found 3 blown diodes on the same power amp side, the amp was working but was biased cold and unbalanced. I rearranged the tubes to get better sets and replaced two that tested bad on my hickok 600a.
Originally I got around 250 watts clean out but after the tube swap I got 300 at various frequencies.
The schematic packet I scanned and sent to him was purchased form ampeg a few years ago, not sure if it is available anymore with the whole move but I did scan it the best I could. Some of the pages are 11x17 and my scanner only went to 11x8 1/2 so I had to scan left and right seperately and then reattach them.
Anyway........ enjoy the schematics and updates.
Click to expand...

Interesting, i know mine still uses plug connections for the most part, the only place the plug connections have been replaced with hard wired connections was a few of the transformer taps, when its been changed from 110v to 240v. There are still a few on that transformer which are the plugs tho.

Whats the reasoning between replacing standard plate resistor with a ferrite bead? Do these handle better/live longer?

Cheers for the info! :D
 
#167
The power amp circuitry is almost exactly the same as the older svt's but they use 12au7's instead of 12BH7's. For some reason, these amps were blowing those plate resistors a lot and how they were mounted it would burn parts of the circuit board badly. They replaced them with ferrite beads which are just a wire with the bead around it to help cancel out any high frequency noise but won't blow.
The connectors I meant is the one for the cable with 5 wires that jumper the preamp board to the power amp board. Most of the other connections are stable. These connectors are the type that would start to melt on the old lee jackson designed ampeg vl1002 series guitar amps because they routed the filament voltage through them and the connector couldn't handle the current.
 
#171
rodl2005 said:
Hey..... thats MY amp!!!!!!! Rig!!!!!! Did U fly out here photo it fly back to Az, post the pic..., Steal my rig??? How'd ya do that???? ;-)Thanks anyway Anderbass!!!!
Click to expand...

You really crack me up rod... Link Removed

rodl2005 said:
I'm STILL dumbfounded on HOW ANDERBASS managed to get over to my house, photo my rig, get back to USA & post the pics on here tho! :eek::help:
Click to expand...


Would you believe... that I've been able to master some of the
same high-speed traveling techniques that good old St. Nick uses?

I thought your riotous-rig deserved a real pic instead of that lousy link, so I just copied your links pic, subjected it to a bit of my funky picture editing skills and posted it.
 
#173
anderbass said:
You really crack me up rod... Link Removed




Would you believe... that I've been able to master some of the
same high-speed traveling techniques that good old St. Nick uses?

I thought your riotous-rig deserved a real pic instead of that lousy link, so I just copied your links pic, subjected it to a bit of my funky picture editing skills and posted it.
Click to expand...

Thanx for that!!! & thanx for not stealing it!!!! I need it tonite;) Worked out the pic biz.
And yes I DO believe you mastered the High-speed travelling techniques - Now to hear U do some High speed "wooten" style bass licks using your new technology!!:p
Well on 2nd thoughts... Just keep playing bass, rather than LEAD!!!!:smug:
Rod.
 
#177
If its any help, I seem to usually get a somewhat more clear, defined and less muffled tone out of my SVT-II with my settings bass and cabs, but I seriously doubt you'd hear anyone complaining if that videos bassist was using an SVT-II instead.
I'd imagine that recording is a blend of DI and a miced SVT-CL. (I liked it)

Thinking of joining our little SVT-II sect? / Possibly found one you cant try-out before buying? ... :ninja:
 
#179
JonathanD said:
Today as I tested mine in the shop I turned it up all the way every knowb full up. It was below speaking level. For ~3 min I played it at that volume and then BOOOOOOOOMMMMMMMM It worked as "normal" level and I was out of that seat so fast I didn't know I was moving. I think the owned came close to wetting himself!

Ah good times with my soon to be best friend....

--------------
Ah, its so pretty seeing 1/2 the front page full of SVTII stuff !
Click to expand...

We haven't heard from you in a while, Did they ever get your amp fixed?
 
#180
I've been thinking about something I'd like to bounce off you guys:
A while back JoathanD started this thread with an interesting Idea about about dual inputting the SVT-II:
http://www.talkbass.com/forum/showthread.php?t=379538

I'd never thought of trying this and really liked the initial results I got from this experiment. I now wonder if my negative results may have been somehow tainted from a previously existing problem my amp had before I ever tried his idea...

Before trying Jonathan's Idea, and every since taking a bad fall, my amp had developed an intermittent problem of becoming stuck in standby mode until I firmly-bumped the amp or flipped the standby switch on and off a few times.

I now wonder if the negative results I got in this experiment were tainted by my pre-existing problem, and we're all now ignoring what could be a very cool and safe connection option with our amps.

I told all this to my tech when I took my amp in for service and he couldn't think of any reason dual inputting would damage anything, but had never actually heard of anyone doing so with this particular model.

Anyway, after repeated tries, my tech never got my amps standby issue to malfunction, so we decided to simply bypass the standby timer relay (among other things) in an attempt to remedy any further problems. I've since used this amp many-many hours. My standby switch and indicator light now works correctly every single time and I haven't experienced any other problems at all...

Now, I really want to try-out Jonathan's Idea again, but am still a little hesitant of using my amp as a guinea pig again... ;)
You guys have any thoughts or comments about Dual inputting an SVT-II?
I know it works fine on many other amps including vintage SVT's, but I haven't found any other mention of anyone doing so with this particular model.
 

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