• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

1969 SVT restoration project

#161
JimmyM said:
OK then, what am I looking at here? ;)

I'm not technically inclined whatsoever. I can spot the tubes on a schematic, but that's about it. What I wanted to know was what does this mod do and (mainly) how does it affect the tone? I find it amazing that guys like you can make sense out of technical data and know what happens because my brain so doesn't think that way. I do appreciate you sharing info, but I'm afraid you'll have to dumb it down a little for me to grok it.
Click to expand...

I highlighted the areas that are different in these two pics...
5-696146differences.jpg

7-706146differences.jpg

It looks like the B+ voltage for the driver tubes first half was lowered on the later ones, mine, compared to the early ones, yours. The B+ originally was 430V then after the 47K resistor it is 160 Volts. The mod changed that supply to be tapped off a later B+ voltage so is only 95 volts on the other side of the 47K so on the plates of the 12BH7's.
I'm guessing this was to reduce the drive a bit going to the power tubes.....
I would be curious to test yours the same way as mine and see what the differences are.....
 
#162
Thanks for the explanation, Tim. I get it now. But I have a feeling I'll never get to test it out in a band situation. My band would kill me if I turned up loud enough to OD the power tubes. I'd like to see what the practical difference is. I imagine they were shooting for a cleaner sound at higher volumes. But if the power tubes aren't driven as hard, wouldn't their output be attenuated as well?
 
#164
darkrider1 said:
Writing the check. That's the hard part for me :-)

$1425 is big bucks for me, especially since my Peaveys & Trace Elliotts work just fine. I would never be able to justify it to my wife (who is also a musician).
Click to expand...

On your first gig with it, you'd definitely be able to justify it. That's about 600 bucks less than these guys who are buying brand new VR heads that are so temperamental.
 
#165
timv said:
Hey Greg, how's it going?
Actually, I remember when we tested your MTI and mine and both were right around 270 watts clean. I've tested another since then with the same. I have another coming in a few days so I'll check that one out also.

My 70' with 6146's still tests at a clean healthy 350 watts clean before any sign of distortion on my scope.

I have a 71' that I am fixing up right now for anderbass on here that initially when I got it only had about 170 watts clean with a weird mixed set of sylvania 6550's and one GE. I put in a good set of sylvanias and still got the same power after bias setup and everything. I don't think those small bottle 6550's are meant for an SVT!!!
I then put in a poorly matched set of EH 6550's and with a quick bias setup got 250 watts clean.
I am now going to refurb the amp, new caps, etc... and possibly install a set of GE's or see what we use. I'll have some good numbers after then.
I also have an SVT II here right now of anderbass's and I will get an output from that before I removed the GE's.
I also have an SVT 300 power amp coming so I am curious what the clean power of that is....
You can say I am a little obsessed with SVT's.....

I'm curious what this 69' is putting out too, My 70 has the factory mod done to the driver tubes to lower there B+, i'm curious if his had the mod done and if not, what it is putting out for power without the mod.
Also, I wonder if this mod helped keep the later ones a bit more stable???

My grandpa was a ham too Bob. I inherited a lot of his 6146B's, some other ham tubes, and some RF coils and other things that I don't know what to do with.

Yah I had heard 330w for the 6146B SVT's, 300W for the 6550 Magnavox SVT's, and as low as 240W for the MTI SVT's with Japanese transformers.

I've measured my early MTI at 300W RMS.....and an 6146B early blue line was in fact 330W RMS. I wonder what your SVT's would spec out at?

Greg
Click to expand...

Hey Greg,
I had my late Skunkworks head tested once buy a tech who was not really very tube savvy and it tested at less than 300 watts, forgot exactly how much (240?) but the power tubes went a few days later which really did not make me happy so I'm sure it was capable of more than that, it never did sound as loud or as good as my Magnavox heads though. I think my Magnavox head with old tubes tested at about 287 Watts by this same guy, the Magnavox heads were always louder for me and more solid. I bought the skunkworks head brand new and could never understand the big fuss about them, I sold it a while ago and just use the Magnavox heads, they're probably due for retubes, I've got 5 years on each with second hand unmatched Svetlana tubes I bought on ebay. Cheapskate, huh? They both still sound good though.

Greg, you should pick up an old Heathkit DX-100, get licensed and try ham radio, it's great, there's an AM subculture that uses all old tube receivers and transmitters.
 
#166
Hey, $1425 is big bucks for me, too! Fortunately, I was able to spread most of the costs out over the course of a few months. But I didn't have to explain anything to my wife. She grossly outspends me. Also, when it's all said and done, I'll have about $2200 into it, and I'm pretty sure I could get well over that out of it as it sits now.

EDIT: BTW, the $1425 was head and cab. I spent only $725 on the head.
 
#167
My man Jimmy. Good feeling to get a project finished isn't it? Time to look at another one. Or, if your're like me, probably already have a few others going on. Keep up the fun and good works. I'm making progress on some of mine, including the 8-10 cab we discussed months ago. Not sure if I mentioned earlier, but all of the speakers appear to be original with 7 of them being indentical '73 CTS 32ohm and 1 dates to '71. Keep it REAL low.:cool:
 
#168
Oren Hudson said:
My man Jimmy. Good feeling to get a project finished isn't it? Time to look at another one. Or, if your're like me, probably already have a few others going on. Keep up the fun and good works. I'm making progress on some of mine, including the 8-10 cab we discussed months ago. Not sure if I mentioned earlier, but all of the speakers appear to be original with 7 of them being indentical '73 CTS 32ohm and 1 dates to '71. Keep it REAL low.:cool:
Click to expand...
Ya, I should go over this thread briefly (except for the embarrassing questions I asked) and catch up on everyone else's projects. That's a real oddball to get a lone 71 in there. You think that one came with it, too? Anything's possible in that transitional time, I suppose.

I'm out of projects, though. Everything I own works now. Kind of a letdown when you think about it. Maybe I should go buy some more crap and fix it up ;)
 
#169
JimmyM said:
Thanks for the explanation, Tim. I get it now. But I have a feeling I'll never get to test it out in a band situation. My band would kill me if I turned up loud enough to OD the power tubes. I'd like to see what the practical difference is. I imagine they were shooting for a cleaner sound at higher volumes. But if the power tubes aren't driven as hard, wouldn't their output be attenuated as well?
Click to expand...

I think the earliest heads had stability issues when played loud so I ownder if this modification was to help with that.

I actually don't test full power through speakers, I have a 4 ohm load that can handle over 400 watts. It is just a resistive load so isn't a perfect example but it is a very standard way of testing that can be reproduced easily.

Anyway, enjoy the amp and I hope pbg or jerrold will chime in with input.....
 
#170
Hey Tim, great to hear from you! How are things?

My SVT is needing a fan still and some caps...probably a rebuild too, but have been doing too many amp repairs to get to it. One of these days hopefully. I've got the Sunn 200S overhauled and modified and it sounds great and records beautifully. I've become good friends with Conrad Sundholm too which is really nice. I've learned a lot about the business side of things, and helped him with some designs of his own that are selling well. He was the co-founder of Sunn back in the day in case you didn't know the name.

Sounds like you've been busy too with amp work?

Jimmy, to measure the power requires some specialized equipment like an oscilloscope and signal generator among other things. You can rest assured that having been just overhauled, you amp is probably making at least 330W RMS which is great!

Bob, I just don't have the time to learn ham stuff and get licensed. Too many other projects going on and a full time job too.

Greg
 
#171
This thread is getting real interesting. Expecially because I have a 6146 head.
Mine is in the shop but in the mean time the guy I got it from loaned me his 74 head.
OMG! Tonal orgasm. I was useing my 57 AVI and the first note made me pop.That SVT really put my old CL to shame.I can not wait to get mine back.
I did a blues fest last night. I played in 2 different bands, 2 hours each. That's a 4 hour orgasm. I'm still smiling.
 
#172
sedan_dad said:
This thread is getting real interesting. Expecially because I have a 6146 head.
Mine is in the shop but in the mean time the guy I got it from loaned me his 74 head.
OMG! Tonal orgasm. I was useing my 57 AVI and the first note made me pop.That SVT really put my old CL to shame.I can not wait to get mine back.
I did a blues fest last night. I played in 2 different bands, 2 hours each. That's a 4 hour orgasm. I'm still smiling.
Click to expand...
That's a 3-day shoulder ache for me ;)

I gotta tell you, though, I use rented backline SVT-CL's all the time and I really can't complain about them. Compared to some of the sorry amps I've been forced to use in the past, they're a godsend. Once I get my Blue Line back, though, I have a feeling I'll be changing my tune, and then I'll curse having to play through a lowly CL ;)
 
#173
JimmyM said:
That's a 3-day shoulder ache for me ;)

I gotta tell you, though, I use rented backline SVT-CL's all the time and I really can't complain about them. Compared to some of the sorry amps I've been forced to use in the past, they're a godsend. Once I get my Blue Line back, though, I have a feeling I'll be changing my tune, and then I'll curse having to play through a lowly CL ;)
Click to expand...


Now all you gotta do, is find a way to leave that Markbass amp at home, and fly with that SVT head-perhaps you can get it it's own seat? The seat belt should be able to hold it in :D

Just kidding of course!! Glad you're finally getting your amp back.
 
#174
Beefbass said:
Now all you gotta do, is find a way to leave that Markbass amp at home, and fly with that SVT head-perhaps you can get it it's own seat? The seat belt should be able to hold it in :D

Just kidding of course!! Glad you're finally getting your amp back.
Click to expand...
Thanks Beef! I may be anal about tone, but I'm not THAT anal.
 
#175
I have a 72 SVT that I re capped and re tubed last year.. But i have a low level hum that i cant trace out.. I will need to take her in to get serviced.. NOthing sounds as good as a real SVT..
Years ago I had one like you with the 6146 tubes and i do think there is a difference.. the 6146 just sounded huge through that older style non- tilt 8x10 cab.

BUt what i would like is to get a nice B15...
 
#176
JimmyM said:
Thanks Beef! I may be anal about tone, but I'm not THAT anal.
Click to expand...

Too bad Bowser can't hook you up with a private jet for you, and that SVT-oh, but then he'd actually have to HEAR the bass!! :eek:

Hey, when you finally get it home, post a pic if you can, ok?
You know, the $1425.00 is a big outlay, but think of it this way;the new SVT-VR reissue is a lot more money, and the guys who know how an SVT is supposed to sound-like Psycho Bass Guy-will tell you that it's not even close to an authentic model, like you have. Now that it's like new, it should last decades longer!

Take care with that bad boy Jimmy :hyper:
 
#177
JimmyM said:
That's a 3-day shoulder ache for me ;)

I gotta tell you, though, I use rented backline SVT-CL's all the time and I really can't complain about them. Compared to some of the sorry amps I've been forced to use in the past, they're a godsend. Once I get my Blue Line back, though, I have a feeling I'll be changing my tune, and then I'll curse having to play through a lowly CL ;)
Click to expand...

The CL's are a fine amp, much better than most others I've tried but it's not a real SVT.There is a difference.
 
#178
Beefbass said:
the new SVT-VR reissue is a lot more money, and the guys who know how an SVT is supposed to sound-like Psycho Bass Guy-will tell you that it's not even close to an authentic model, like you have.
Click to expand...

This type of comment really gets to me so i just had to respond and ask, do you own an SVT-VR and an original? I currently have both and while an original (pre 1980)SVT is my favorite bass amp, my SVT-VR sounds and feels just as good and has the same power.

BTW, congrats to you Jimmy for finally getting your '69 SVT up and running. now it should go another 30 years or so.
 
#179
johnk_10 said:
This type of comment really gets to me so i just had to respond and ask, do you own an SVT-VR and an original? I currently have both and while an original (pre 1980)SVT is my favorite bass amp, my SVT-VR sounds and feels just as good and has the same power.

BTW, congrats to you Jimmy for finally getting your '69 SVT up and running. now it should go another 30 years or so.
Click to expand...


I guess you missed the part where I said "those who know what an SVT is supposed to sound like" I don't own an SVT, never said that I did, and if you are unhappy about that, show me where I said different. I said PSYCHO BASS GUY-he owns authentic SVT's, and has test driven the SVT-VR.

I'm outta here-jeez, the stupidest s*** gets people's panties in a bunch around here-especially those who don't read the posts carefully. Sorry if I insulted one of your obviously favorire amps. Personally, I play a Fender-if you think that sucks, who gives a rats ass? I enjoy my amp-enjoy yours. Aren't there more important things in the world to worry about??
 

Latest posts

Top Bottom
Back