The art amps have a hollow tube running down each side of the sink, you can see them if the ends are removed. If you were hardcore serious about doing it and your friend had the know how, you could just run coolant through the tubes to keep the amp cool. I ran a first series art 600 bridged mono at 4ohms for several years with coolant, a small fuel pump, small radiator and fan, and it never failed. Of course it was only running normal A/B. The first art series seemed to slightly drop power output when ran hard, which is why I decided to run coolant. (ppi also sold the art amp specific coolant system back when the art amps were made if I remember correctly)
The cooling was mainly a gimmick. Look at the attached image. You can see that there is a lot of thin aluminum between the transistors and the tube. Unless you're using chilled water (well below room temperature), the water cooling won't do much more than fan cooling would.
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Perry is calling that one right! It was kind of a gimmick back then. And to prove my statement lets look at the amps of equal power back then. They all had FINS on the sink to add surface area to aid heat emission, except for Hifonics and Proton which were a different class amp with their special multi-stage power supplies. If you compare the heatsink surface area of any Art Series amp to any other Class AB amp except Hifonics and Proton and do the simple math of surface area you will see the Art series had less surface area then most amps back then. This is why they offered liquid cooling to this very artfully designed amp. PPI Art series was one of the only smooth bodied Art deco amp designs available, and while sleek and sexy it had less heat sink emission surface area then just about any other amp on the market at that time. So in comes the liquid cooling option for 2 ohm operation and below to extend operation before thermal rollback and shutdown. Oh and the later PC and PCX series had internal fins on the inside of the sink so as to appear smooth on the outside, and the cooling fan blasted cooling air over those fins inside the amp.
I had a A1200 in for repair that had been liquid cooled and in competition a while back and the power devices were just fine, but the rest of the amp cooked off like it had been in a oven. It needed a internal cooling fan, and PPI added them on the later PC and PCX class amps instead of liquid cooling, like DUH!
The SIP driver boards leaked DC all over the place, all the SMD solder joints on the SIP were cooked grey and cracked from heat and all the electrolytic caps were cooked to a different color and all the shrink wrap sleeves were split and popping off. DC offsets were all over the place, and uncontrollable and the amp needed to be completely gutted to bring it back to life correctly.
Such a waste, and a huge disappointment for me and my client as he paid top dollar huge money for a nice looking door stop. < there is a lesson here about used competition car amps I think>.
So the water cooling while possibly good for the power devices still leaves the rest of the amp to melt down under the excessive heat build up of driving a amp into extremes like that one had seen. And the only time I would consider liquid cooling is if you were to place your Class AB amps under plexiglass on show with no air flow to them or if you wanted extended service at 2 ohms or less operation. Then liquid cooling makes sense for these amps. At least to me anyway....
Oh and Class A is so inefficient you will most likely see 80% of your 12 volt power draw came back to you as pure heat load on the amp and its internals. It is also a great way to turn a 300 watt amp into a 30 watt amp. I don't know anyone that has beat that law of physics yet. And if anyone has please send me their link so I can learn the new laws of science and keep up with that Nobel prize winner that invented that amp.
I had a A1200 in for repair that had been liquid cooled and in competition a while back and the power devices were just fine, but the rest of the amp cooked off like it had been in a oven. It needed a internal cooling fan, and PPI added them on the later PC and PCX class amps instead of liquid cooling, like DUH!
The SIP driver boards leaked DC all over the place, all the SMD solder joints on the SIP were cooked grey and cracked from heat and all the electrolytic caps were cooked to a different color and all the shrink wrap sleeves were split and popping off. DC offsets were all over the place, and uncontrollable and the amp needed to be completely gutted to bring it back to life correctly.
Such a waste, and a huge disappointment for me and my client as he paid top dollar huge money for a nice looking door stop. < there is a lesson here about used competition car amps I think
>.So the water cooling while possibly good for the power devices still leaves the rest of the amp to melt down under the excessive heat build up of driving a amp into extremes like that one had seen. And the only time I would consider liquid cooling is if you were to place your Class AB amps under plexiglass on show with no air flow to them or if you wanted extended service at 2 ohms or less operation. Then liquid cooling makes sense for these amps. At least to me anyway....
Oh and Class A is so inefficient you will most likely see 80% of your 12 volt power draw came back to you as pure heat load on the amp and its internals. It is also a great way to turn a 300 watt amp into a 30 watt amp. I don't know anyone that has beat that law of physics yet. And if anyone has please send me their link so I can learn the new laws of science and keep up with that Nobel prize winner that invented that amp.
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So basically you're reiterating what I said yet still agreeing with Perry that the liquid cooling was a gimmick and not effective? 
Its not a gimmick when it does what I claimed, which is drop the temperature low enough to keep power output stable when running 2 ohms stereo / 4 ohms mono. I never claimed it magically made the amp capable of running full power in class A mode, I simply suggested it to the OP to aid in his efforts. I know for a fact the liquid cooling worked as demonstrated in my setup for several years. I actually had the amp several years previous to using the liquid cooling and could notice power output change when running fully loaded on fairly hot days. Houston summers are not amp friendly when running with no a/c and the windows down. I purchased the (a600, not .2) amp at an EZpawn in houston for $60 and it had the driver board issue. I immedially sent it to PPI and they performed all necessary repairs for only $150 if I remember correctly and it never had a problem after. I didn't run liquid cooling until a few years later, Louisiana summer weather is also not amp friendly when running windows down and no a/c.
That being said, not everyone runs their amplifiers in competition mode every day. I really only did the coolant mod to help it run a that much lower of a temperature for extended life and allow longer bursts at full power if desired. The amp was actually in perfect shape on the inside when I sold it, nothing was cooked / baked. Of course trying to run in full class A would create a lot more heat but you could also use fan cooling through and over the amp and coolant. Not saying it would be worth it to spend so much effort but I'm sure there would be someone crazy enough to try
Its not a gimmick when it does what I claimed, which is drop the temperature low enough to keep power output stable when running 2 ohms stereo / 4 ohms mono. I never claimed it magically made the amp capable of running full power in class A mode, I simply suggested it to the OP to aid in his efforts. I know for a fact the liquid cooling worked as demonstrated in my setup for several years. I actually had the amp several years previous to using the liquid cooling and could notice power output change when running fully loaded on fairly hot days. Houston summers are not amp friendly when running with no a/c and the windows down. I purchased the (a600, not .2) amp at an EZpawn in houston for $60 and it had the driver board issue. I immedially sent it to PPI and they performed all necessary repairs for only $150 if I remember correctly and it never had a problem after. I didn't run liquid cooling until a few years later, Louisiana summer weather is also not amp friendly when running windows down and no a/c. That being said, not everyone runs their amplifiers in competition mode every day. I really only did the coolant mod to help it run a that much lower of a temperature for extended life and allow longer bursts at full power if desired. The amp was actually in perfect shape on the inside when I sold it, nothing was cooked / baked. Of course trying to run in full class A would create a lot more heat but you could also use fan cooling through and over the amp and coolant. Not saying it would be worth it to spend so much effort but I'm sure there would be someone crazy enough to try
Perry is calling that one right! It was kind of a gimmick back then. And to prove my statement lets look at the amps of equal power back then. They all had FINS on the sink to add surface area to aid heat emission, except for Hifonics and Proton which were a different class amp with their special multi-stage power supplies. If you compare the heatsink surface area of any Art Series amp to any other Class AB amp except Hifonics and Proton and do the simple math of surface area you will see the Art series had less surface area then most amps back then. This is why they offered liquid cooling to this very artfully designed amp. PPI Art series was one of the only smooth bodied Art deco amp designs available, and while sleek and sexy it had less heat sink emission surface area then just about any other amp on the market at that time. So in comes the liquid cooling option for 2 ohm operation and below to extend operation before thermal rollback and shutdown. Oh and the later PC and PCX series had internal fins on the inside of the sink so as to appear smooth on the outside, and the cooling fan blasted cooling air over those fins inside the amp.
So the water cooling while possibly good for the power devices still leaves the rest of the amp to melt down under the excessive heat build up of driving a amp into extremes like that one had seen. And the only time I would consider liquid cooling is if you were to place your Class AB amps under plexiglass on show with no air flow to them or if you wanted extended service at 2 ohms or less operation. Then liquid cooling makes sense for these amps. At least to me anyway....
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That being said, not everyone runs their amplifiers in competition mode every day. I really only did the coolant mod to help it run a that much lower of a temperature for extended life and allow longer bursts at full power if desired. The amp was actually in perfect shape on the inside when I sold it, nothing was cooked / baked. Of course trying to run in full class A would create a lot more heat but you could also use fan cooling through and over the amp and coolant. Not saying it would be worth it to spend so much effort for relatively low class A output capability but I'm sure there is someone crazy enough to try
Quoting myself for my late edit attempt
It was a gimmick because no one else offered it and the heatsink was too small for the amps to run low ohms like they were rated at. Sorry to not clearly make my point but I really want you to focus on the heatsink surface area issue. I still feel the liquid cooling was a bandaid/gimmick to solve a real engineering issue with the amps heatsink design. Sometimes things can go hand in hand on a issue like this. And I am sure it is also depending on every-bodies point of view of the engineering issue. This was mine, even though I may seem to be on both sides of the fence...
There are a couple of definitions of "gimmick", and if you have to use one for ppi's coolant system I would choose the latter.
gim·mick (g m k) n. 1. a. A device employed to cheat, deceive, or trick, especially a mechanism for the secret and dishonest control of gambling apparatus.
-or- my choice:
an ingenious or novel device, scheme, or stratagem, especially one designed to attract attention or increase appeal
I totally understand their reasoning behind the heatsink design. And while insufficient for continuous low impedance setups (2 ohms stereo) on the normal art (not talking about the pro art) models, it is plenty of area for continuous normal load operation. There is also more to look at than the amps' external surface area. You have to look at transistor location in relation to the area with greatest contact to air as well.
There are a few issues when people debate this subject:
-transistors mounted vertically, using primarily the outer edges of the amp will be slower to conduct heat to the top of the amp with largest area. This is similar in one way to the arts' conduction from the inner area (top surface) out to the side areas, but their transistors are already closer to the top surface.
-fins may have more surface area but can also act as insulators when there is low air flow (trunk mounting for example) or when airflow is not running directly through the fins (across them instead of through). In those cases, the heat is actually radiating from one fin to the next and the air is acting almost as an insulator so the overall actual radiating area of the amp can actually be pretty limited.
This subject has been debated since differing amp sink designs have been around. The reasoning behind the smooth art sinks is to allow air to smoothly pass over the surface with no rough obstructions (fins) hindering air movement. The smooth surface promotes convection of surrounding air which allows contact with other air. Its even explained in their literature. I'm not saying its better than fins, especially with a directed fan, but its not an ill thought out design. They didn't use internal fans which would have helped internal components immensly in competition setups, but for the average high end listener who just wanted great sounding music and great looking equipment they are excellent.
gim·mick (g m k) n. 1. a. A device employed to cheat, deceive, or trick, especially a mechanism for the secret and dishonest control of gambling apparatus.
-or- my choice:
an ingenious or novel device, scheme, or stratagem, especially one designed to attract attention or increase appeal
I totally understand their reasoning behind the heatsink design. And while insufficient for continuous low impedance setups (2 ohms stereo) on the normal art (not talking about the pro art) models, it is plenty of area for continuous normal load operation. There is also more to look at than the amps' external surface area. You have to look at transistor location in relation to the area with greatest contact to air as well.
There are a few issues when people debate this subject:
-transistors mounted vertically, using primarily the outer edges of the amp will be slower to conduct heat to the top of the amp with largest area. This is similar in one way to the arts' conduction from the inner area (top surface) out to the side areas, but their transistors are already closer to the top surface.
-fins may have more surface area but can also act as insulators when there is low air flow (trunk mounting for example) or when airflow is not running directly through the fins (across them instead of through). In those cases, the heat is actually radiating from one fin to the next and the air is acting almost as an insulator so the overall actual radiating area of the amp can actually be pretty limited.
This subject has been debated since differing amp sink designs have been around. The reasoning behind the smooth art sinks is to allow air to smoothly pass over the surface with no rough obstructions (fins) hindering air movement. The smooth surface promotes convection of surrounding air which allows contact with other air. Its even explained in their literature. I'm not saying its better than fins, especially with a directed fan, but its not an ill thought out design. They didn't use internal fans which would have helped internal components immensly in competition setups, but for the average high end listener who just wanted great sounding music and great looking equipment they are excellent.
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I know you like these amps but these heatsinks are close to the worst as far as heatinsking goes. Look at the area under the transistor. They have a deep groove that makes the aluminum thinner. This increases thermal resistance and hinders cooling.
Fins are better in every respect as far as cooling goes. They increase surface area which helps cooling.
For a good heatink, you need low thermal resistance between the semiconductor and the area that will dissipate the heat. On this amp there is a thin area directly behind the semiconductors that limits the heat transfer. There is very little surface area due to the smooth surface.
On the more efficient heatsinks, the fins also have ridges. These increase surface area even more.
If a smooth surface was better, the manufacturers of heatsinks would produce smooth profiles (no fins).
Fins are better in every respect as far as cooling goes. They increase surface area which helps cooling.
For a good heatink, you need low thermal resistance between the semiconductor and the area that will dissipate the heat. On this amp there is a thin area directly behind the semiconductors that limits the heat transfer. There is very little surface area due to the smooth surface.
On the more efficient heatsinks, the fins also have ridges. These increase surface area even more.
If a smooth surface was better, the manufacturers of heatsinks would produce smooth profiles (no fins).
Oh for crying out loud, I never said smooth surface sinks were better. Only that they are not bad. They obviously have the lowest surface area because they are smooth (is anyone surprised?) but they are not horrible. And yes, of course I like the arts (and most of the early finned ppi amps as well) but I'm not blindly defending the design. Btw, I'm currently running an adcom four channel (internal fan cooled) and earthquake phd3 (er... I meant ph5000) so no ppi bias (no pun intended) as far as I'm concerned. I'm a fan of many amps, mainly american made but several japanese as well. Don't let my username fool you.
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