I completely uninstalled the fan. Bought a $1 Store clip on fan to hang on the back of the head. Keeps cooler and quieter than the stock fan ever did. Been using this setup for 20 years. Never had an issue.
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Ampeg svt cl fan question
- Thread starter wolfkeller
- Start date
Blowing cool air directly onto burning tubes can crack glass. Tubes go bye-bye.
A fool who succumbs to his folly has no regrets.
If he manages to survive, the regrets may be too much.
If he manages to survive, the regrets may be too much.
I would consider replacing the fan with a high grade one, doesnt sound too complex.
What fan and what connector? If its something small with a similar connector to say pc fans, I would do that kinda replacement.
What fan and what connector? If its something small with a similar connector to say pc fans, I would do that kinda replacement.
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I’ve switched out the fan in my VR with this https://www.amazon.com/dp/B009OWVUJ...t_i_CQRDF7KDPYBYG70M8KY6?_encoding=UTF8&psc=1
But the spec are different for the CL per Aged Horse. I have a heritage cl that is loud as, as well. Maybe I’ll go on the hunt for a replacement. OP Do you have a pic of the connector?
But the spec are different for the CL per Aged Horse. I have a heritage cl that is loud as, as well. Maybe I’ll go on the hunt for a replacement. OP Do you have a pic of the connector?
“Too hot” is measurable. You have to find out what that number is.
Ah, running like that since over a year with my V4: 80mm computer fan blowing air on the tubes (pushing toward the back) to prevent the faceplate being crazy hot. I use a DC 12v universal PS set at 5v. Really quiet and sure better heat dissipation.
My two YGL3’s without fan have the metal chassis running incredibly hot, at the back however contrarily to the V4. One of the two (the head only version, obviously) had previously an AC fan, removed by a previous owner and I left it like that.
On my YBA3, the AC fan was like a Boeing taking off. I’ve bought a similar AC fan, believing it was the old fan but the new one was equally noisy. A 120mm computer fan with a similar arrangement than the V4 did it.
Pretty sure this is incorrect.
Amps I own with stock fans directly cooling the output tubes:
- Trace Elliot V4, V6, and V8.
- Aguilar DB359.
- Mesa D180.
Tubes are a lot tougher than people give them credit for. See special rating and performance data for the 6146W. G-force testing and vibration specs are mentioned.
Tubes can take some heat, it’s the surrounding components and eventually the solder joints that are more of a concern. Circulation of the air is important in confined areas. Maximum glass bulb temperatures vary depending on the tube but for a 6550A it’s 250 dec C (482F), same for a 6L6GC. Some places on the glass will be hotter than others, that’s because some structures within a tube run hotter. You don’t generally want one power tube running very hot and another power tube way cooler due to uneven distribution of flowing air. A fan should ideally even that out and exhaust heat.
Thermal shock is not going to happen when blowing a fan onto a tube with room temperature air.
http://www.tubecollectors.org/rca/archives/6146w(65).pdf
https://drtube.com/datasheets/6550a-ge1972.pdf
http://www.tungsol.com/tungsol/specs/6l6gcstr-tung-sol.pdf
Tubes can take some heat, it’s the surrounding components and eventually the solder joints that are more of a concern. Circulation of the air is important in confined areas. Maximum glass bulb temperatures vary depending on the tube but for a 6550A it’s 250 dec C (482F), same for a 6L6GC. Some places on the glass will be hotter than others, that’s because some structures within a tube run hotter. You don’t generally want one power tube running very hot and another power tube way cooler due to uneven distribution of flowing air. A fan should ideally even that out and exhaust heat.
Thermal shock is not going to happen when blowing a fan onto a tube with room temperature air.
http://www.tubecollectors.org/rca/archives/6146w(65).pdf
https://drtube.com/datasheets/6550a-ge1972.pdf
http://www.tungsol.com/tungsol/specs/6l6gcstr-tung-sol.pdf
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smaller fans have to run faster , which makes them noisier. Plus this makes the solution a lot more complicated.
@wolfkeller
First: as I've said before, running anything but the stock fan voids your warranty and poses the possibility of turning your amplifier into valueless junk.
If you're willing to assume that responsibility, read on
Since I don't own an SVT Classic, I'm assuming that your amp is set up like the one in these pictures.
Rear cover off:
As I pointed out here, in this long discussion, "Heat likes to go up, but spilled drinks like to go down." If this were an amp intended for home use, we could just let the heat rise harmlessly out the top, like this:
But we can't do this with something that will be gigged and hauled around in vans.
Well, if we're only using it at home, we can! The obvious solution is to remove the amp chassis from the case. It's no longer portable, and you can burn yourself on the tubes and probably figure out a way to shock yourself badly, but the heat will rise out of the top and you very likely won't need a fan. (See the four KT88s on that McIntosh?)
I did this with my Peavey T-Max, a tiny picture of which you can see in my avatar. The fan was only necessary because the entire thing was designed to be hidden in a rack. With the top off, I was able to disconnect the fan, and the giant heatsink didn't even get warm.
Moving on to solutions that leave the amp in its case:
You can usually find a manufacturer and part number on the stock fan, and then find the datasheet for that fan, which will tell you its rated airflow in CFM -- and, usually, a rated noise figure. Then, you search the Internet for fans of the same size (and depth, if depth is an issue), and which push the same or greater CFM. Although noise figures are not always accurate or calculated the same way, some of them will likely be a lot quieter than others. I was able to find a replacement fan for my T-Max that moved roughly the same amount of air, but was substantially quieter.
You can remove the back panel (with the fan) entirely, and either run with no fan at all (dangerous), or with a clip-on fan like @dopejohnpaul mentioned. In this case, I would recommend a contactless temperature probe that will let you check exactly how hot the transformers, tubes, and chassis are getting. (I can't tell you how hot is too hot, but you can take a measurement immediately after removing the back cover and attached fan, and another measurement later, after the back cover has been off for a while and the temperature has stabilized.)
If you're willing to make a new back panel (or hack up your current one, which I don't recommend), you have more options:
You can use a larger fan that moves similar CFM. All other things being equal, a larger fan moves air more quietly than a smaller one.
You can use two quieter fans that move similar CFM between them.
You can make a mounting bracket that holds the fan up, but leaves the back panel completely open otherwise. In this case, you can probably use a much lower CFM fan, since the grille isn't trapping most of the air inside and needing the positive pressure of the fan to push it out...but I'd still measure temperatures with the probe to make sure I was getting the results I expect. (I don't know how much those transformers cost, but I bet they're expensive to replace if you cook one.)
There's a lot more you can do if you're willing to build a new case or hack up the existing case...but then it wouldn't really be an SVT Classic anymore!
First: as I've said before, running anything but the stock fan voids your warranty and poses the possibility of turning your amplifier into valueless junk.
If you're willing to assume that responsibility, read on
Since I don't own an SVT Classic, I'm assuming that your amp is set up like the one in these pictures.
Rear cover off:
As I pointed out here, in this long discussion, "Heat likes to go up, but spilled drinks like to go down." If this were an amp intended for home use, we could just let the heat rise harmlessly out the top, like this:
But we can't do this with something that will be gigged and hauled around in vans.
Well, if we're only using it at home, we can! The obvious solution is to remove the amp chassis from the case. It's no longer portable, and you can burn yourself on the tubes and probably figure out a way to shock yourself badly, but the heat will rise out of the top and you very likely won't need a fan. (See the four KT88s on that McIntosh?)
I did this with my Peavey T-Max, a tiny picture of which you can see in my avatar. The fan was only necessary because the entire thing was designed to be hidden in a rack. With the top off, I was able to disconnect the fan, and the giant heatsink didn't even get warm.
Moving on to solutions that leave the amp in its case:
You can usually find a manufacturer and part number on the stock fan, and then find the datasheet for that fan, which will tell you its rated airflow in CFM -- and, usually, a rated noise figure. Then, you search the Internet for fans of the same size (and depth, if depth is an issue), and which push the same or greater CFM. Although noise figures are not always accurate or calculated the same way, some of them will likely be a lot quieter than others. I was able to find a replacement fan for my T-Max that moved roughly the same amount of air, but was substantially quieter.
You can remove the back panel (with the fan) entirely, and either run with no fan at all (dangerous), or with a clip-on fan like @dopejohnpaul mentioned. In this case, I would recommend a contactless temperature probe that will let you check exactly how hot the transformers, tubes, and chassis are getting. (I can't tell you how hot is too hot, but you can take a measurement immediately after removing the back cover and attached fan, and another measurement later, after the back cover has been off for a while and the temperature has stabilized.)
If you're willing to make a new back panel (or hack up your current one, which I don't recommend), you have more options:
You can use a larger fan that moves similar CFM. All other things being equal, a larger fan moves air more quietly than a smaller one.
You can use two quieter fans that move similar CFM between them.
You can make a mounting bracket that holds the fan up, but leaves the back panel completely open otherwise. In this case, you can probably use a much lower CFM fan, since the grille isn't trapping most of the air inside and needing the positive pressure of the fan to push it out...but I'd still measure temperatures with the probe to make sure I was getting the results I expect. (I don't know how much those transformers cost, but I bet they're expensive to replace if you cook one.)
There's a lot more you can do if you're willing to build a new case or hack up the existing case...but then it wouldn't really be an SVT Classic anymore!
Thie image is of a SVT-VR, the SVT-CL’s fan is mounted on the front panel behind the black grille cloth (see below) so things are a bit different. They redesigned the CL’s air flow as well as the position and grouping of power tubes in an attempt to improve the circulation.
Still, a quieter fan will lower the mechanical noise level.
Still, a quieter fan will lower the mechanical noise level.
Thank you! That's very helpful.
In this case, the problem is even more obvious: the fan is trying to blow air out through the grille cloth. This doesn't work very well, and it causes the fan to be even noisier than it would normally be.
I can see three options, in addition to the standard "pull the chassis out of the case":
1. The destructive solution would be to cut a hole in the grille cloth over the fan, and replace it with a wire grille, as on the photos in my previous post. Then you could use a much quieter fan, and it would still pull just as much (likely far more) air out of the case.
2. The non-destructive solution would be to remove the existing front grille and make a new one, again with a wire grille and a much quieter fan. You can be as elaborate as you want with this, depending on how nice you want it to look.
3. You could probably get away with just removing the front and rear grilles and letting passive airflow do the work...but I'd want to test that with the contactless temperature probe, as above.
What I'm seeing here is exactly what I suspected: no design effort was put into cooling these heads. They were built to look a certain way, then when they ran too hot in the case, they just stuck a fan wherever. The result is a very noisy head.
(If I were responsible for design, the first thing I'd try is an intake fan on one side of the case and an exhaust fan on the other. This would maintain the front panel aesthetics, while allowing for much better airflow with much quieter fans. I'm willing to bet I could cool an SVT basically inaudibly with a couple 120mm computer case fans in this configuration.)
agedhorse
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So after much searching to find comparable fans I found this.
https://www.alliedelec.com/product/8500n-8500n/70105498/
36cfm and 34db. iPhone db app says stock is 70db.
https://www.alliedelec.com/product/8500n-8500n/70105498/
36cfm and 34db. iPhone db app says stock is 70db.
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I don't try to out-think design engineers unless there is a known design problem. The fan on my MTI-era SVT reminded me of what a turbine-engined locomotive might sound like. So I did my homework. I found a fan with the same physical dimensions and nearly-identical performance specs. They're not that spendy. It is quiet now, and working as designed.
If you went from no air flow to ice cold air flow on already hot tubes, I could see this maybe being an issue. Don't think it would happen with the fan being on at all times.
On my CL, the air blows out the front. It came this way from the factory.