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Help with Ampeg Blue Line SVT Restoration

M

mr1956

Feb 6, 2009
13
0
#1
I own an Ampeg Blue-Line SVT bass head that I just dragged out of storage after three years. I purchased it used in the early 1980's I think and amazingly it still works. When I got it, the power switch was broken off and I soon replaced both the power and polarity toggle switches.

The serial number on this amplifier is 7108171 and it was manufactured by the Ampeg Co., Inc., in Linden, NJ.

While I make my living as an electronics/electrical technician, I surmise that this may be a pretty early model SVT and may want to have it restored by someone more familiar with this amplifier than I.

Can anyone on this forum recommend someone who is qualified to do such a restoration? I know of one group in St. Louis but was wondering who else is out there. BTW, this is actually the newest of my two bass amps. The other one is a 1966 Fender Bassman.

Also, does anyone have any images of the power cable connection into the chassis. Have yet to find something showing the original configuration.

Thanks,

Curt Newport
 
#2
Mine came with a grounded replacement so this may not help you, but here's a pic showing the power cord arrangement that was on my 72 Blueline when I got it. (my tech's since instaled a new power cord with a strain relief)

SVTguts15.jpg


It seems reading the numbers/date codes on the transformers and pots are the most accurate method of figuring the date of manufacture on these amps.

As far as a top SVT tech to consider, you'll find serveral people recommending Dennis Kager at Central Jersey Music in this TalkBass search link: http://www.google.com/custom?hl=en&...Kager&btnG=Search&sitesearch=www.talkbass.com
 
#3
Your's looks similar to what mine was when I bought it used; an an extension cord with a knot inside. I changed it to what you see in the attached images. But I'd still like to find out what the original configuration was.

Thanks,

Curt
Potomac, MD
 
#4
Doesn't matter what it was before. If it's a 2-prong currently, it should be replaced with a 3-prong.

Most techs familiar with tube amps should be able to help you get it up to scratch, but the Central Jersey place has an advantage that the owner was on the original SVT development team at Ampeg.
 
#5
If your having an issue getting a nice 3-wire cord to fit a strain relief without enlarging the amps rear panel hole... I know my tech had to shave my new power cord down just a bit to pull this off. I think he might of also had to also enlarged the new replacement strain relief's center hole just a bit too.

Man, that thing is cleeean looking! With your SVT's non-painted chassis, I'm thinking your somewhere in the neighborhood of 69 or 70 there.
 
#6
Thanks for the messages. It is no problem putting a good AWG 14 power cable in there at all. I was just hoping to do something close to what was originally installed. But so far, I have been unable to find any images of an unaltered power cable installation for this year SVT

I have attached another image of the chassis. Actually, I have not even started cleaning yet. Just spent part of today going over the circuit board with a Q-tip and alcohol. Starting to look pretty good now.

Thanks,

Curt
 
#8
anderbass said:
Mine came with a grounded replacement so this may not help you, but here's a pic showing the power cord arrangement that was on my 72 Blueline when I got it. (my tech's since instaled a new power cord with a strain relief)


It seems reading the numbers/date codes on the transformers and pots are the most accurate method of figuring the date of manufacture on these amps.

As far as a top SVT tech to consider, you'll find serveral people recommending Dennis Kager at Central Jersey Music in this TalkBass search link: http://www.google.com/custom?hl=en&...Kager&btnG=Search&sitesearch=www.talkbass.com
Click to expand...

HI

Could you take one more clearer picture of the whole black PC board?
Thank you.
 
#10
BTW, I see you're all set for 6146's in that head. Don't let anyone talk you into the 6550 mod! There are enough SVT's with 6550's out there. 6146's are excellent tubes that you can get for half the price of 6550's. Just don't touch the plate voltage caps with it plugged in.
 
#11
I took a couple of more pics. Sorry the resolution is not better but this forum does not seem to like high-res images.

Yes, it is set up for the 6146B tubes and I was very careful when I removed them. Not worried so much about the voltage as I deal with 2,600 volts in my job with Navy underwater vehicles so I have a healthy respect for such things. Just didn't want to damage the tubes.

I purchased the head used at Giant Music, in Falls Church, VA in the early 1980's if I remember correctly. It was in rough shape when I got it but I played out with it in DC for about four years or so; since then, it's mostly been stored away except for about two years ago when I used it again for a while. I was moving some things around and decided that it deserved some attention. I never owned the original 8x10 cabinet as it was just two big and heavy. Instead, I used a 4x10 cabinet and 1x15 PA cabinet with it and it worked very well indeed.

While I recognize that the original AC cable was two conductor, this amplifier obviously needs to have a properly grounded cable. However, a "restoration" dictates that something should be returned to its original condition as much as practical; hence, my desire to have it look as original as possible.

I do need to find a technician's manual for this year SVT so I can properly set up the bias. I'm sure they're out there.

I would like to date the amp but this may be difficult. But from what I have been seeing, it might be a pretty early model. It deserves to be pampered I suppose.

Curt Newport
 

Attachments

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#13
One past pic before I'm off to bed. I'll accept 1970. The only other thing I've seen resembling a date was one of the components had a 12-69 stenciled on it. It's an old one for sure.

C. Newport
 

Attachments

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#14
All roads are pointing to 70. BTW, all the SVT's I've seen with 6146's had the plate caps white and the wires green. So I don't think the wires you have are stock. I could be wrong, but I've never seen it. Not a big deal in the grand scheme of things, though. Probably a safety issue at one time. Those caps are much heftier looking (and more than likely safer) than what Ampeg used.
 
#19
anderbass said:
Most of us end up using off-site photo hosting to post pics here. I use http://photobucket.com/.
You gotta sigh up first but its free and pretty easy to figure out.
Click to expand...

I'll check out the other site to post images and I've already got a shopping list for Allied Electronics. Today, I need to examine the toggle switches so I know what to replace them with. A model made by Carling is pretty close to the original.

Let me get some things going this morning and I'll post some more images.

Curt
 
#20
Bassmec said:
I can't look at more pictures of very old lytic caps without getting very nervous.:confused:
Click to expand...

Haha.. I agree! Maybe the OP should think about substituting the power supply caps with modern caps. It does NOT screw up the Vintage Sound (they do LOOK different, though) but improves it and makes that baby sound like brandnew - just like when it came out of the shop in 1970. Expect tighter lowend and clearer and stronger midrange.

The other thing is, that the 5W plate-resistors have obviously been replaced within the years. That is not uncommon because they blow when a tube fails. Originally they are those sandfilled ceramic resistors, but not carbonresistors (as this SVT is now equipped with).
The ceramics blow much quicker in case a tube fails, so it does protect all the rest of the amp much better.

You can get decent supply at "fliptops" for example.
 

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