ampeg cooling fan

I was wondering also for my old SVT and found this thread a while back:

http://www.talkbass.com/forum/showthread.php?t=225770

Not sure it's exactly what you're looking for since your's is a newer one, but I hope it may give you a start.

I'd be curious also if any SVT guru's (paging Psyco!) can reference a great quiet replacement fan.

 

There are alot of computer fans that will work just fine for less than $25. Just get the specs of the stock fan first. Such as size. example:120mm x height, rpm and/or cubic feet per min. of capacity. Then do a search for quiet computer fans and buy one that fits those specs. The noise that a fan makes will be measured in db's(less is better) Here is a link to a quit fan website. This is just an example. Make sure of the specs you need first.
http://www.quietpcusa.com/Quiet-Computer-Fans-C6.aspx

 

cl0r0x70 nailed it.

Better develop some new resources for tube amps guy; I get the feeling my posting days here are numbered.

 

Believe me; I know.

 

They are also different than the original 70's heads that they are supposed to be an exact replica of.

 

So Mouser.com? My SVT fan also sounds like a jet taking off and I have been pondering a switch, too. So for a vintage one it is 119mm and I need at least 60cfm? Anything else I might need to know?

 

Not exact, I lobbied for closer, but they are not quite. Some things are simple practicality issues, some availability, some "other".

Tubes in preamp are same innards, different numbers...... the original used composite tubes that are 1/2 12AX7 and the other half 12AU7. They are quite specialized, and have been available on and off ("on" right now, tomorrow who knows?). Supply has been bad enough even back in the 1970s/80s that a substitute circuit was developed by Ampeg and/or MTI many years ago. It isn't as good, but they did what they could, even then, long before SLM got involved.

The VR simplifies that by using the halves of separate tubes for that (12AX7 and 12AU7) in the same circuit. That DOES change what parts of the circuit are shared.........

The final cathode follower is not a 6C4 as it was in SVT and in the original 500 SLM units. the 6C4 was a big noise issue in the original 500 units..... better that it's gone.

The driver tube in the power section is a 12AU7. In that particular circuit, the difference is hardly noticeable, since even in the original circuit there is a large grid resistor on each power tube, which cuts the possible grid current drastically.

The original tube is essentially identical to a 12AU7 but with larger current capability. With the huge series resistor, you CANNOT get to those current values.......However, if you want, the original type will plug right in.

The other bigger changes are:

All-PC board construction, vs original with part PC board (duplicated on the original 500, BTW).

The use of the bias indicator lights.

Automatic delay on standby.

No, it is NOT a 'clone" down to each wire etc. Many would have liked that, and I think it might have been the best plan, if it could have been done at any reasonable cost now.

However, it is what it is, which is the same circuit etc as the original, re-packaged.

I will guarantee, that even if SLM had literally hidden an original SVT inside each one with the SLM name on the back, there would STILL be folks saying "Well, they messed it up, just as I figured they would".

So I suppose the changes really don't matter that much as far as universal acceptance......

 

I thought yours was 120mm. I pulled 119 off that link to that other thread..from a vintage one.

 

Could you post the part number? I ran the search and get "no results found". Love my VR as well but the fan is sooooo loud. I wouldn't mind replacing that part.

 

An SVT-VR when it's working is as good as any other SVT out there (except for those very few original 69's like mine---insert evil laugh here).

But Jerrold, you have to admit that latter-day Ampeg's reputation has been one they've earned. St. Louis Music did a great job at innovating new products for the Ampeg line. When they worked, they were fabulous. But there were quite a few issues with reliability, and a lot of it was based around inexcusable problems like cold solders. I personally sent my SVT 3 Pro back to SLM twice because of a distortion problem, and each time it came back and worked for a month then re-developed the same problem. I currently have a local tech looking at it to decide whether to fix it or scrap it for parts. And you shouldn't have to do that with a 13 year old amp that costs $1000 new.

And don't even talk to me about the use of pressboard in their cabs! Even an Ampeg alumnus like yourself has to admit that it's completely wrong to use pressboard in cabs.

Ampeg products have been and continue to be my number one favorite of all time. And to be fair, many products SLM made worked just fine and still do. But we really shouldn't be having these problems in professional-level amplifiers on such a widespread scale, and for God's sake, do something about the pressboard!

 

Well, I agree. I did some of the innovating, so I don't mind agreeing!

As far as the "pressboard", never was any, at least not what I would call "pressboard". "OSB" was used, in places I don't agree with. I have personally done demos of the difference for various people named Kornblum...... OSB is a chipboard product that is "oriented" like plywood. Close, but no cigar, ir is too easy to "punch through" if you run into something, and tends to break if dropped too far. OK for your roof, or floors.... your house may have it.

Too bad it is a "green" product..... be nice if it DID work, but it's just a bad application.

And, just about the time of the purchase, it was indeed changed to birch ply. Mon Rominee knows, he did some of the economic study while with EAW (another LOUD division).

Reliability has been an issue more at certain times than others. I won't go into reasons, but they are there, especially with the solder. Correct, back then no excuse... solder was a "mature technology" and shouldn't have been an issue. After 20+ years, it becomes one in many products, though.

These days, figure on 3 to 5 years for anything..... after that it may just fail and be essentially un-repairable. No-lead solder is a problem, and will be until better stuff that won't "whisker" and crack is developed.

 

Jerrold, I think one of these days you must write a 'tell all' book.

 

3 to 5 years...my grandpa is turning over in his grave

Yeah, the world of solid state is turning to disposable products. That's all well and good for $50 DVD players. Not in a $1000 amp. If the company eats the disposability, I'm fine with it. But once that warranty runs out, I sure am going to hate being told that nobody works on solid state equipment anymore when something breaks. And is there going to come a day when a $2000 SVT is disposable?

Glad to hear that they quit using the cheap stuff on the cabs, though. That makes me feel better about recommending them to people. I do really dig the sound of most of the cabs.

 

It's really the worst for things with small parts....... surface mount items, which everyone is going to. Computers are the real problem.... tiny traces, hair-sized component leads......

There's a reason you still are not allowed to use no-lead for avionics. And wht the military and communication companies are allowed to use lead solder.

SVTs probably won't be an issue. But all that fancy DSP stuff may be.