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1969 SVT restoration project

Not to belabor the point, but you shouldn't be attempting to power up your amp AT ALL. There are several things in an SVT that could be on edge and a hard-start (non variac) could cause serious catastrophic failure. I also think it's funny you're so dead set on having to have that Amperite relay, yet you're willing to sub 12AX7's or 12AT7's for the 12DW7's. The 12DW7 is essential for the amp to work properly. The relay is not. What I said before stands, if you value the amp and to a lesser extent, your life, don't try to repair or diagnose it yourself in ANY capacity.
Even though you know much more than me and I bow to your wisdom, I figured I can't have anything more catastrophic than not putting out any sound, which it was already doing. And I subbed the 12AX7 in the preamp because the only appreciable difference between a 12AX7 and a 12DW7 is the 12AX7 has high gain on both sides, whereas a 12DW7 is a 100/20% mix of gain, otherwise it's pretty much the same tube, and apparently Ampeg only wires them to use the 12AX7 side of the tube. So even though I may have done the wrong thing, and I'm not disagreeing with you, I did take into consideration many things before I tried it, and didn't just go at it willy nilly. I did a very short test, then immediately unplugged it, and now I won't be turning it back on until it comes back from the shop.

Thanks, though. I really do appreciate your warnings and your advice has been top notch.
 
I figured I can't have anything more catastrophic than not putting out any sound, which it was already doing.

The amp could literally go up in flames. There's a lot of high voltage stuff in an SVT that can arc and burn up pretty spectacularly. Normally functioning SVT's often burn holes through their PCB when they have a tube short. It's a VERY dangerous amp to mess around with.

And I subbed the 12AX7 in the preamp because the only appreciable difference between a 12AX7 and a 12DW7 is the 12AX7 has high gain on both sides, whereas a 12DW7 is a 100/20% mix of gain, otherwise it's pretty much the same tube,

That's not the ONLY difference. The 12AU7 side handles much more plate current than the 12AX7. That's crucial in both the preamp and the phase inverter.

and apparently Ampeg only wires them to use the 12AX7 side of the tube.

That's not true. There's not a single unused half in the whole amp. I think you may have confused a reference to the 6C4 preamp tube which basically is only one half of a 12AX7.

I did a very short test, then immediately unplugged it, and now I won't be turning it back on until it comes back from the shop.

If there is something badly wrong, simply turning the power on, and especially turning the standby on, can INSTANTLY do major damage. I'm not saying that it will happen, but that it CAN happen, and there's no need to chance it. That's the reason good techs use a variac to bring up questionable equipment; you can regulate the amount of voltage the amp is getting and monitor its behavior at lower voltages so you can spot a problem while it is still relatively harmless, and even then, damage can still occur.
 
Well I sure do appreciate the advice, Psycho. Fortunately, nothing got fried or set on fire, but I will definitely not do that again, as you scared me pretty good! It's out of my hands now as I took it to Birddog today. He told me that he did a 6550 conversion to a 69 a few years ago and may actually still have the original plate caps for the 6146B's! Yippee!

So either tonight or tomorrow, the cab work starts. Gotta pull the speakers and get them into the speaker shop for recones, then pull that cheesy fabric store vinyl and strip and sand the cab. The the next immediate decision will be to get those hideous screws that Ampeg used to put the speakers in or leave the socket/flat screws that are in it (sorry, can't think of what they're called at the moment). NOS is one thing, but those original speaker screws are a real pain to work with.

In the meantime, here is a list of parts I still need that I can't find. If any of you know of anyone who stripped an old 69 SVT and can get these parts for it, I would appreciate you contacting me:

1. Rear coverplate for head

2. ID plate for back of the cab (a recreation is fine for both of these as long as they're identical to what came on it in 1969)

3. NOS knobs for head (I need 4, but will buy a whole set if they're mint or near mint)

3. Pattern for cutting the tolex (need one of these for a B-15N double baffle, too)

BTW, condition is not all that important on the rear coverplate and ID plate for the cab. By now they'd be beaten to shreads, anyway. But the higher the quality, the more I'll pay.
 
I called our local speaker repair place for a quote on getting my cab reconed, and I was quoted $75 a cone to get them restored to exact SVT specs and colors. Even though these guys are Eminence distributors, that was the best they could do on price. And I believe they are giving me their lowest price because a good friend of mine works there. And Bruce from Fliptops must be on vacation or something because he didn't return my email for a reconing quote. However, I don't expect it to be much less than that if at all, and with shipping it will probably be more.

On the other hand, new Eminence 32 ohm SVT speakers are $60 apiece and 8 of them are $450. So I have quite the dilemma here...do I spend $600 and keep the original baskets or spend $450 and get all new speakers?

Looks like I have some thinking to do this weekend. Anyway, hopefully you wise folks will have some words of wisdom for me whilst I take this broken monitor back to Best Buy. It just brightened up on me and won't un-brighten no matter what I do. So let me know what you all think.

UPDATE: Got Bruce on the phone and his quote for reconing was the same. But he said if you can afford it, get them reconed because you can't get them with alnico magnets anymore. So for that reason alone, I'm leaning toward reconing.
 
UPDATE: Got Bruce on the phone and his quote for reconing was the same. But he said if you can afford it, get them reconed because you can't get them with alnico magnets anymore. So for that reason alone, I'm leaning toward reconing.
If they're Alnico, keep them and get them coned.
 
You should get them reconed. The EH SVT speakers just aren't as good, period.

BTW, I wish you luck on getting your amp restored. It appears that by disagreeing with the personal beliefs of some people here about various issues that I will no longer be allowed to post here very soon. I'm sure that makes a few people happy, as they have been trying to make this happen for many years now. I guess if I gotta go, it might as well be in an SVT thread... :scowl:
 
You should get them reconed. The EH SVT speakers just aren't as good, period.

BTW, I wish you luck on getting your amp restored. It appears that by disagreeing with the personal beliefs of some people here about various issues that I will no longer be allowed to post here very soon. I'm sure that makes a few people happy, as they have been trying to make this happen for many years now. I guess if I gotta go, it might as well be in an SVT thread... :scowl:
Don't you dare get thrown off before I'm done!!! ;)

Hey, I've had problems here for the exact same reason. Nobody wants you to tell them they're an idiot for modding an original pre-CBS Precision, and I feel it's my duty. Honesty is welcome in my threads, even if I get called an idiot occasionally.

Anyway, always feel free to contact me by email if you get booted here. [email protected].

So I'm taking the speakers in for reconing since they are the originals with the square magnets. Gotta hurry, though, they close at 6:30!
 
You should get them reconed. The EH SVT speakers just aren't as good, period.

BTW, I wish you luck on getting your amp restored. It appears that by disagreeing with the personal beliefs of some people here about various issues that I will no longer be allowed to post here very soon. I'm sure that makes a few people happy, as they have been trying to make this happen for many years now. I guess if I gotta go, it might as well be in an SVT thread... :scowl:

My vote is to keep psycho here, he knows his stuff, we need someone here who really knows these amps, not many do and that includes 95% of the amp repair shops around. There are always wimps in every forum who get mad or cry if someone offends their sensitive natures:crying:, if they don't like what they read why don't they just go to another thread, very easy, that's what I do. Psycho's blunt and has no patience for fools, (I found out the hard way) but he is very often correct.

BTW he is right about these amps they have very high voltage in them 700-800 Volts which will KILL you, if you don't know what you are doing don't turn them on. I use a variac whenever I turn anything on that hasn't been on for a while or is questionable. The standby switch when turned on connects the high voltage I believe on the secondary side of the power transformer to the rest of the circuit. I turn that and the power switch both on and bring them up slowly on a variac monitoring the plate voltage at the same time, it should come up uniformly with the variac going up, if it doesn't you have a problem and should shut it down immediately. If at 120 Vac you have 700 VDC, at 60 Vac you should have approx 350Vdc etc. There is an approx 1-7 relationship between input voltage and plate voltage.

The old speakers sound better than the new ones.
 
It's not actually pairs, but "sides". The svt will let you match 2 different sets or three tubes using pot, so basically you'll need two individually matched trios.

Hey I don't want no druggie tubes in my SVT!
a matched sextet is even better, even unmatched tubes will work OK and most people won't know the difference as long as they are close, same manufacturer etc.
 
If I had this SVT - I would make a players beast out of it. Which would be bringing this baby "back" into post-6146 era of the early 70s with nicely perfectly matched 6550s in it.

Definitely NO 12AX7 except of the one single for chann 2! There was a reason why they put in those 12DW7 and changed the power section to 6550s after just a single production year.

They are stronger and more reliable. The stones fried at least half of their 69 SVTs on their tour due to reliability issues of the 6140s SVT heads afair.

No use of a delay tube if you have the standby. By the way - If yout wanted to bring it to 100% original specs then you would also have to reinstall the original head mounted 3-pole speaker cable anyway. But for a player that all makes no sense. Does it?

I would NEVER change that original Iron butterfly stamped tolex. But thats just me...

Dont those original speaker oktetts just handle only 200 Watts? Which was the reason that you would needed two of those cabinets in the old days?

As for the low weight of the Markbass tube amp: The output transformer is a conventional heavy one, bringing surely 50% of the total weight. The mains transformer is a very light weight toroidial. Both of them transformers are mounted on the poplar made cabinet, which leads to a really tiny and lightweight alu chassis. The whole head is very small and relies on a temperature controlled cooling fan.

DONT bann Psycho from this Forum!!!!! He is such an institution when it leads to questions about tube amps, and especially SVTs.
 
You should get them reconed. The EH SVT speakers just aren't as good, period.

BTW, I wish you luck on getting your amp restored. It appears that by disagreeing with the personal beliefs of some people here about various issues that I will no longer be allowed to post here very soon. I'm sure that makes a few people happy, as they have been trying to make this happen for many years now. I guess if I gotta go, it might as well be in an SVT thread... :scowl:

That sucks, if you go, I'm going. You've always been very helpful, and a straight shooter. If we can't have people lke you here, whats the sense?

BTW 3 years on the XM200C Yorkville and not a single issue! This thing is solid a s a rock. I thought I'd mention it, because I sought your advice on that, and it worked out very well for me :hyper:
 
You should get them reconed. The EH SVT speakers just aren't as good, period.

BTW, I wish you luck on getting your amp restored. It appears that by disagreeing with the personal beliefs of some people here about various issues that I will no longer be allowed to post here very soon. I'm sure that makes a few people happy, as they have been trying to make this happen for many years now. I guess if I gotta go, it might as well be in an SVT thread... :scowl:

That's terrible. You're one of the few people that post on the amp forum that have the experience to back up their opinions concerning tube amps. I've only found you to be fair and correct in the way you express them ( as in you stick to facts and don't get personal), so I can't see what the problem could be.

I haven't forgotten the personal reply you sent me to a few questions I had about my SVT when I bought it used, that helped me get things right and probably saved me from heartache and expense down the line.

JimmyM, good luck with the restoration, you'll have a great sounding SVT soon by the looks of it.

I have that VTV issue about SVTs if there is anything in it you might want to know. I'll dig it out and see what it says about the earliest versions.
 
One Drop, please do, especially if there are detailed pics. A scan of that would be most appreciated.

Hoss, the tech I took it to suggested putting 6550's in it, too. I told him that are 100,000 SVT's on the market with 6550's and a dwindling few with 6146B's. A lot of these early SVT's have been changed over, and not too many haven't. So that was never on the table for discussion. And I would hope that if you ever run across one of these that you do change it out to 6550's, because that will help the price on mine go up! But we do agree on the Iron Butterfly stencil.

I wish I'd have thought to bring my camera to the speaker repair shop. It's Link Removed, and my pal Doc (the most brilliant guitarist/bassist/violinist/steel guitarist/vocalist you've ever heard in your life) works there. They also did the recones in the early 90's and did a great job so that's who I take all my recones to. He pulled out an SVT cone to show me what it looks like new, and it's a pretty deep shade of blue. My recones had significantly faded to light blue in 17 years, and he told me that the originals probably started out that exact color and faded to the light gray they are now. Then he tried to talk me out of reconing the newer cones because they were still good. He said if I was just going to keep it and play out with it for a while that I should just recone the 4 originals, but if I was selling it, I should do all of them.

I thought about it, then thought if I keep it for a few years before I sell it, then the new cones will have faded and I'll have to get all new cones to sell it yet again, so this way I just pay for 8 recones and not 12 altogether, plus they'll fade at equal color levels so color matching won't be an issue. He thought I was being stupid. I was actually being pretty smart. Well, if I was smart, I'd have paid to get all 8 speakers reconed back in the 90's at the same time and it would have been $35 a speaker instead of the $81 I'm getting hit with now. But I've learned from that mistake, and that's what counts, right? I'll forget the money I spent in a year. But I won't have cherry looking matching cones and that will always eat at me.

So with the new tubes and the head and speakers in the shop, the technical side of the restoration is humming right along. And next on the big wheel o' fun is lots and lots of sanding! I don't have a belt sander but I do have an electric sander, so maybe that'll help take the edge off sanding a little. I've decided to do the re-tolexing myself. I did a pretty decent job on it before without knowing the first thing about it. And it's about the only thing in this restoration process that I'm capable of doing myself (gotta do something yourself, right?).

Here's a shot of all the speaker baskets, plus a shot of one close-up. I have no idea what the numbers mean, but I see a 69, so that has to mean 1969, I'm sure. Check out the bottom of the cab, it's the only paper label left on it. Couldn't find a tube chart or a serial number label on the head, but the cab still has it by some miracle.

And please let me beg once again for detailed pics of original tolex jobs on straight-back cabs and dollies. I've found a couple but they're never detailed enough to see what's doing, or the head's in the way or they don't photograph the bottom. Email them to [email protected]. Thanks again for all your help, folks! I'm not cutting you in when I sell it, but thanks just the same ;)
 

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One Drop, please do, especially if there are detailed pics. A scan of that would be most appreciated.
I would too if possible please.
Hoss, the tech I took it to suggested putting 6550's in it, too. I told him that are 100,000 SVT's on the market with 6550's and a dwindling few with 6146B's. A lot of these early SVT's have been changed over, and not too many haven't. So that was never on the table for discussion. And I would hope that if you ever run across one of these that you do change it out to 6550's, because that will help the price on mine go up!
I'm with you in the 'keep it unique/rare', but also understand the practicality of the 6550 mod.

Do you need some tubes? I may have some singles in the stockpile you can have if there are some there. I'll also keep an eye out as I get offered all sorts of odd tubes.
Here's a shot of all the speaker baskets, plus a shot of one close-up. I have no idea what the numbers mean, but I see a 69, so that has to mean 1969, I'm sure.
Following up earlier comments, mine don't look like that. Yours are definitely alnico, mine are mudmagnets.