What advantages would cooling of tubes have?
My first thought is about noise, Would it cause less noise?
How can I cool down the tubes?
I have thought about drilling some holes in the chassie near the tubesockets and use some fans,
this is probably the simplest method.
Other thoughts is about using some kind of heatspreaders at the tubes, maybe they can then also functions as shields.
A more advanced method would be to use some kind of liquid, this liquid has to be circulated through some pipes which are coupled to the tubes.
I have heard very little about cooling of tubes, in fact the only thing I have heard was about a mic amp for pro use who used some kind of liquid cooling.
My first thought is about noise, Would it cause less noise?
How can I cool down the tubes?
I have thought about drilling some holes in the chassie near the tubesockets and use some fans,
this is probably the simplest method.
Other thoughts is about using some kind of heatspreaders at the tubes, maybe they can then also functions as shields.
A more advanced method would be to use some kind of liquid, this liquid has to be circulated through some pipes which are coupled to the tubes.
I have heard very little about cooling of tubes, in fact the only thing I have heard was about a mic amp for pro use who used some kind of liquid cooling.
Hi,
TUBE COOLERS.
Several industrial tubes use cooling in various forms such as forced aircooling, oil cooling etc.
EIMAC.
Cheers,
TUBE COOLERS.
Several industrial tubes use cooling in various forms such as forced aircooling, oil cooling etc.
EIMAC.
Cheers,
Cooling a valve reduces noise. A Sony microphone used Peltier effect cooling. The problem is that the glass envelope isn't very round or consistent unless specially specified, making it difficult to obtain good thermal contact. One way around the problem would be to suspend the valve upside down in a finned bath of oil.
Fans are noisy. Even the quiet ones. Nevertheless, pointing a fan at a valve cools it quite effectively.
Fans are noisy. Even the quiet ones. Nevertheless, pointing a fan at a valve cools it quite effectively.
If you are designing from scratch, choose tubes that don't run too hot, ie 6V6 instead of EL84, 6550 instead of EL34 etc. The bigger the glass envelope the more surface area and better cooling, i guess.
Most tubes seem to run fine in free air unless you have a high ambient temperature. Norway is about the same as NZ so you are ok
As for reduced noise, have you heard how loud computer fans are? They suck, I think any decent music system should be fanless.
But good ventilation is a great idea, I try and recess my tubes into the chassis a little to get airflow around them, the so called "chimney effect". Keeps them cooler.
Most tubes seem to run fine in free air unless you have a high ambient temperature. Norway is about the same as NZ so you are ok
As for reduced noise, have you heard how loud computer fans are? They suck, I think any decent music system should be fanless.
But good ventilation is a great idea, I try and recess my tubes into the chassis a little to get airflow around them, the so called "chimney effect". Keeps them cooler.
fdegrove said:
Made commercially by Pearl HiFi, they are available at least at in Parts Connexion NA & Moth Audio in the UK. They are cheap enuff that one has to have 2nd thots about DIYing them.
Bill has an article on them.
An externally hosted image should be here but it was not working when we last tested it.
dave
> What advantages would cooling of tubes have? Would it cause less noise?
If you could cool the cathode enough to reduce noise a measurable amount, it would just stop working at all. The cathode MUST be hot to make those clingy little electrons jump off where the plate and grid can affect them. And emission is like 3rd-power of cathode temperature, while noise changes very slowly.
If you are over-heating the plate, cooling will increase life. However small glass tubes don't have enough thermal contact between the plate and any part you can put a cooler onto. Some huge (kilowatt) transmitter tubes do have provisions for cooling the plate directly. But don't over-do it: the transmitter tubes are designed to run hot and won't getter well if you manage to cool them too much.
If you work the tubes very hot and turn them off and on many times a day, the seals may crack. Cooling around the pins is usually something to check if your tubes go gassy quickly.
> drilling some holes in the chassis near the tubesockets and use some fans
Do as much of that as you like. It will keep the resistors and other parts on the socket from cooking and drifting over time.
If you could cool the cathode enough to reduce noise a measurable amount, it would just stop working at all. The cathode MUST be hot to make those clingy little electrons jump off where the plate and grid can affect them. And emission is like 3rd-power of cathode temperature, while noise changes very slowly.
If you are over-heating the plate, cooling will increase life. However small glass tubes don't have enough thermal contact between the plate and any part you can put a cooler onto. Some huge (kilowatt) transmitter tubes do have provisions for cooling the plate directly. But don't over-do it: the transmitter tubes are designed to run hot and won't getter well if you manage to cool them too much.
If you work the tubes very hot and turn them off and on many times a day, the seals may crack. Cooling around the pins is usually something to check if your tubes go gassy quickly.
> drilling some holes in the chassis near the tubesockets and use some fans
Do as much of that as you like. It will keep the resistors and other parts on the socket from cooking and drifting over time.
Interesting post, PRR, and I agree with most of your points.
However, (you knew this was coming), noise is only signficant with small-signal valves, and it doesn't solely come from the shot noise of electron emission. There are also some distinctly dodgy insulators with considerable voltage across them that are connected to a high-impedance input (the control grid). The micas.
The anode cools by radiation, but some of this is absorbed by the envelope, raising its temperature, and simultaneously reducing the temperature differential between the anode and envelope, which reduces anode cooling. The micas are in close thermal contact with the anode, and insulators become leakier as temperature rises. Alternatively, it could be that hot micas begin to release water vapour, causing grid ion current.
I accidentally proved the noise theory by fitting snug-fitting screening cans made of 22mm copper pipe with a slot in the side to B9A valves. After half an hour, there was a lot of LF noise, and the valves were hot. I removed the cans, and the noise subsided. The cans, being relatively shiny, had prevented radiation.
However, (you knew this was coming), noise is only signficant with small-signal valves, and it doesn't solely come from the shot noise of electron emission. There are also some distinctly dodgy insulators with considerable voltage across them that are connected to a high-impedance input (the control grid). The micas.
The anode cools by radiation, but some of this is absorbed by the envelope, raising its temperature, and simultaneously reducing the temperature differential between the anode and envelope, which reduces anode cooling. The micas are in close thermal contact with the anode, and insulators become leakier as temperature rises. Alternatively, it could be that hot micas begin to release water vapour, causing grid ion current.
I accidentally proved the noise theory by fitting snug-fitting screening cans made of 22mm copper pipe with a slot in the side to B9A valves. After half an hour, there was a lot of LF noise, and the valves were hot. I removed the cans, and the noise subsided. The cans, being relatively shiny, had prevented radiation.
Hi,
So do I... but there's more to tube coolers than that; lowered microphony is one thing.
If we'd want to extend tube life regardless of top performance we could just as well lower cathode emission by reducing heater voltage/current.
Cathode emission is not going to be affected by a cooling element on the glass envelope, so I seriously doubt that in this application it's going to affect this in any negative way.
Yep....I found the best screening cans to be matte in colour, i.e. none reflective.
There's a lot more that can be said about this, we're entering muddy waters here.
Cheers,
So do I... but there's more to tube coolers than that; lowered microphony is one thing.
If we'd want to extend tube life regardless of top performance we could just as well lower cathode emission by reducing heater voltage/current.
Cathode emission is not going to be affected by a cooling element on the glass envelope, so I seriously doubt that in this application it's going to affect this in any negative way.
Yep....I found the best screening cans to be matte in colour, i.e. none reflective.
There's a lot more that can be said about this, we're entering muddy waters here.
Cheers,
Well, I don't know if guitarist care much about noise(tube noise) in their amps when they are playing loud, but cooling could probably extend the life of the tubes.
I have searched a bit for some low-noise fans, and I found a couple which have a noise of 12 dBA, thats substantially lower than the noise produced by computer fans.
I have searched a bit for some low-noise fans, and I found a couple which have a noise of 12 dBA, thats substantially lower than the noise produced by computer fans.
cooling of vacuum tubes
First, you have to know reason for cooler. Amps with baby tube EL 84,EL34 , EL 88, don't need cooler.Big tube like 6c33b need cooler for socket and area near .I made on my OTL 6C33B two cooler 12v 12 W with 25 db noise.For put down this noise very efecty put down voltage on minimum 6 V.
First, you have to know reason for cooler. Amps with baby tube EL 84,EL34 , EL 88, don't need cooler.Big tube like 6c33b need cooler for socket and area near .I made on my OTL 6C33B two cooler 12v 12 W with 25 db noise.For put down this noise very efecty put down voltage on minimum 6 V.
Re: LET'S KEEP IT COOL...
Especially if used in conjunction with an iso-socket. Parts Connexion talked Bill into redesigning his isolation socket so that it plugs into the existing socket which means they can be installed without soldering (althou at the expense of another contact)
dave
fdegrove said:
Especially if used in conjunction with an iso-socket. Parts Connexion talked Bill into redesigning his isolation socket so that it plugs into the existing socket which means they can be installed without soldering (althou at the expense of another contact)
dave
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