Chris Robinson Posted August 18, 2001 Share Posted August 18, 2001 Hi guys ... anybody have any experience in keeping tube amps cool when racked in cabinets? I'm about to refinish the family room with all new cabinets and a wet bar; they're being made now and should be done by Labor Day. I've made a provision in the left-hand upper cabinet (above the cabinet for the LH Cornwall) for four or five shelves. I'm planning to put the DVD on the bottom, the Denon above that, then each Anthem AMP1 (tubes) on their own shelves about that, and topped by the McIntosh MC-30. The Denon runs pretty cool, but the tube amps put out a lot of heat. Mfg'er recommends a FOOT above each Anthem. If I go off that spec for spacing the shelves, I'll need like 5' of cabinet which I don't have (I run into the bottom of the vaulted ceiling 92" above the floor)... I've got like 39' to play with. Cabinet is fronted by two glass doors. The way I figure it, I've got a thermal rise in the cabinet (with the doors closed) that resembles a chimney! The amps will overheat in no time and the tubes will fail early. SOoooooo ... any suggestions (other than keeping the doors open)? I'm actually testing some hard disk drive fans above the Athems right now; they will keep the tubes cool until the cabinet air heats up. If I leave the glass doors open during operation, that might be enough. The other thing I'm considering is installing two 3-1/2" computer case fans (brushless DC) which will suck out the air in the cabinet and vent it out of the top behind the crown molding. Only problem is that with all these fans come noise Plus the AC power supply that needs to power all these DC fans. There's GOT to be a thermal engineer among you or someone who's addressed this problem before ... or even some Leonardo-types who are particularly creative. Any ideas? Maybe I could vent the inside of the cabinet from the central AC? Thanks -- ------------------ Klipsch 1968 ALK Cornwall "II"s (LF/RF) ALK Belle Klipsch (Center) Klipsch Heresy (RR/LR) Klipsch KSW-12 sub Sonic Frontiers Anthem AMP1 (driving Cornwalls) Sonic Frontiers Anthem AMP1 (driving Heresy's) McIntosh MC-30 (driving Belle) Denon AVR-4800 Toshiba SD-3109 DVD Quote Link to comment Share on other sites More sharing options...
The_Shark Posted August 18, 2001 Share Posted August 18, 2001 Chris, Although I'm not a thermal engineer I am an electronics tech with 20 years experience. I've worked with a lot of equipment that has been installed in 19" equipment racks. All the racks I've seen over the years pretty much use the same scheme. Fans either push air or draw the hot and exhaust it out the top of the cabinet. If the fan(s) is mounted on the top the fan would suck the air out of the cabinet there would be louvered opening(s) with a dust filter covering the opening. Some cabinets are just the opposite fan mounted at the bottom pushing hot air out an opening in the top of cabinet. The most important thing is that there is airflow through the cabinet. Cool air is drawn in and hot air is exhausted out. From what you described you are going to have a heck of a time getting good air flow throught the cabinet. Being that you have tube amps you are going to need a lot of flow through the cabinet. The approach you take depends on a couple of factors 1) Is your cabinet free standing, recessed / part of wall or mounted to wall? 2) Is the top or any sides open / unobstructed to place an intake / exhaust vent? 3) Does the shelves take up the full interior depth? Another factor to consider is equipment placement. If this were a tall cabinet, say 6 or 7 feet. The amps could be placed on the top shelf. And if the top of you cabinet was unobstructed you might be able to get away with just ventilating the top shelf by placing a exhaust fan on the top (lid)/rear of cabinet and vents on top (lid)/front of cabinet. This way there wouldn't be any unsightly grills that could be seen. Another tip those DC fans you mentioned more that likely will not provide adequate airflow. You're going to want a muffin/ boxer fans maybe a couple. 4.7" is a common size and come in a 115v AC variety. These type fans move ~100 to 120 CFM depending on the model. You should be able to pick one up at Radio Shack if not we use Newark electronics where I work www.newark.com . Rotron is one manufacturer of this type fan. Newark lists them as a "AC Tubeaxial Fan". Using AC muffin fans means you can wire them to plug in a regular outlet strip and not have to mess with a power supply. Hope this helps, The_Shark Quote Link to comment Share on other sites More sharing options...
WMcD Posted August 18, 2001 Share Posted August 18, 2001 One thing I've read is that two fans running at half speed will move as much as one at full speed. The fans could be placed somewhere so they are not facing directly out into the room, just for some noise baffling. Also, I'll assume you'll have an air inlet (or exhaust)of area approximately equal to the fan area, if not larger. One last thought is that the equipment creating the most heat should be placed nearest the exhaust. The thought is that that heat doesn't move though the entire cabinet and heat other components. Probably the room HVAC is not a good idea if it cycles on and off. Gil Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted August 18, 2001 Author Share Posted August 18, 2001 Thanks, guys ... Shark, good stuff too ... I'll follow up on that. I think the muffin fan sounds like a good idea ... the problem right now is equal air INTAKE. Need to talk to the cabinet guys. Stay tuned, thanks again. ------------------ Klipsch 1968 ALK Cornwall "II"s (LF/RF) ALK Belle Klipsch (Center) Klipsch Heresy (RR/LR) Klipsch KSW-12 sub Sonic Frontiers Anthem AMP1 (driving Cornwalls) Sonic Frontiers Anthem AMP1 (driving Heresy's) McIntosh MC-30 (driving Belle) Denon AVR-4800 Toshiba SD-3109 DVD Quote Link to comment Share on other sites More sharing options...
Mighty Favog Posted August 18, 2001 Share Posted August 18, 2001 Didn't BGW or Raxxess make a fan that mounted on the top of the rack? Either sitting horizontal to force the air upward or mounted in the top two-unit spaces to ehaust air into the room? Maybe one more at the bottom to blow air in? Sorry, just a lot of stupid thoughts on too little sleep. Also, StudioTech ( http://www.studiotech.com/racks/ultrarack.html )makes their free standing rack doors with a metal (hole filled ) mesh that in front (sides too), maybe you could just buy the front door to one of these? They come in 48" and 60" heights. ------------------ Tom KLF-20 Mahogany McIntosh C33 Rotel RB-1080 Yamaha PF-800 Turntable/ Sure V15 Type V Cartridge Ortofon VMS-30 mkII Cartridge Stanton 999SS Cartridge Carver TL-3100 CD (McIntosh MVP-841 coming August 21, 2001) Yamaha K-1020 Cassette dbx 1231 EQ H.H. Scott 830z Analyzer Monster Interlink 400mk II Monster Interlink 300mk II Studio Tech U-48RW Cabinet Monster Power HTS-5000 Original 12ga. Monster Cable Enough empty boxes for a fire hazard! This message has been edited by tblasing on 08-18-2001 at 11:53 PM Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted August 19, 2001 Author Share Posted August 19, 2001 Tom, thanks ... too little sleep, huh? Know that feeling ... was up yesterday a.m. at 2:45 staring at the ceiling, thoughts of tubed cabinets dancing through my head. Wish it were sugarplums or something even sweeter ... Anyway, back to the matter at hand Both you and Shark (and Gil) have some good ideas. Think I'll scrap the DC fan ideas and just go with an AC muffin fan (funny name ...) ... Shark, how noisy are these puppies? The left side of the cabinet setup actually shares a common wall with the garage; maybe I could vent it right into the garage with a deal like you vent a bathroom fan outside. If the noise from the fan could be vented into the garage, well ... who cares? Since the Cornwall cabinet below this rack will be open, perhaps I'll just rout some 1/2" slots (maybe 12" long or so) below the amp rack (which is the top of the Cornwall cabinet). That would permit a source of cool air at the bottom to be drawn through the cabinet and vented at the top and out. Chris Quote Link to comment Share on other sites More sharing options...
Colin Posted August 19, 2001 Share Posted August 19, 2001 I think you are on the right track, muffin fans can be pretty quiet, especially if you mount them with some rubber washers from the plumbing department, holes or slot in the bottom will give you cross ventalation, just be sure to dust off your amps when they are cool, the aire blwoing across them will get the tubes dustier more quickly than without the fans ... ------------------ big old Cornwalls, Bottlehead 2A3 Paramour tube amps, Dynaco series II tube pre-amp, Rotel CD player, KSW200 & LF10 subs Quote Link to comment Share on other sites More sharing options...
The_Shark Posted August 19, 2001 Share Posted August 19, 2001 Chris, As Colin said good quality 4.7" muffin fans are fairly quiet. I'd say less noise than a computer power supply fan. Don't scrimp either get ones with ball bearings not the bronze sleeve, they last longer. Keep in mind cabinet design and fan mounting / placement are important factors. Poor design / placement (i.e. mounting fan on the interior) can cause the fan noise to resonate within the cabinet. Also be carefull of anything that might be loose and could vibrate. Like the glass doors you mentioned, good quality latches in conjuction with rubber bumpers on the corners can minimize vibration. Colin is also correct about the dust collecting so be sure to use a filtered intake vent. This will cut down on the dust drawn into your cabinet. I do like the idea of exhausting to the garage if it's possible. That would really be convienient. A short duct through the wall and mount the fans on the garage side. Heck that should take care of any noise or vibration problems. You will still want to have air intake inside. I'm sure you garage is not climate controlled and would be drawing warm air in the summer. And also tend clog the intake air filter much quicker. Cheers, The_Shark Quote Link to comment Share on other sites More sharing options...
WMcD Posted August 19, 2001 Share Posted August 19, 2001 One additional thought. It might be that only the tube equipment needs forced cooling. So maybe they can be segrigated (spell Czech) to their own area with a glass door in front. Maybe add a dial thermometer in there to monitor temperature. On the other hand, you'll want access to the Denon and DVD etc. You'll have the doors to that area open a lot, which would compromise the forced air design. Maybe this will give you some ideas. Gil Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted August 20, 2001 Author Share Posted August 20, 2001 Thanks, you guys. Good ideas ... think we're closing in on this ... Shark, you said you work at Newark Elec ... I went to your website and looked at the Rotron and NMB fans ... boy, there are thousands of them! Can you help me with the selection process? If I were to top vent to the garage, and I put the fan in the top of the cabinet, is there a model that will vent sideways to some tubing that I could run through the garage wall? Low profile would help since it can hide behind the crown molding on the top of the cabinet. All the fans I looked at just show the fan and nothing else. Then there were things called "boxers" ... I don't know if these are the fans plus some housings ... I guess what I'm asking for is some recommendation for the complete assembly from either you or one of your product line folks. Also, if I vented to the garage, your last post suggested I put the fan in the garage (wall I assume) and PULL the air through the wall (perhaps I could just put a hole in the side of the cabinet in the top 10" or so and just run it directly through the wall, bypassing the top vent altogether? As Gil points out, if the glass doors are open, the venting is pointless, so I'll probably need to put the fan on a separate wall switch to use when everything's buttoned up. The electrician will be coming in a few weeks to rough in all the wires before the cabinets go in; we've got time. If it would be easier for me to call you at work and fax you some drawings, it might be easier. I'm in San Jose today and flying back to Boston tomorrow. Have some time this afternoon if that works. My work number is 800-922-7667 x224 if you want to leave a message with contact info. Many thanks again to all for contributing to my little project! Chris ------------------ Klipsch 1968 ALK Cornwall "II"s (LF/RF) ALK Belle Klipsch (Center) Klipsch Heresy (RR/LR) Klipsch KSW-12 sub Sonic Frontiers Anthem AMP1 (driving Cornwalls) Sonic Frontiers Anthem AMP1 (driving Heresy's) McIntosh MC-30 (driving Belle) Denon AVR-4800 Toshiba SD-3109 DVD Quote Link to comment Share on other sites More sharing options...
The_Shark Posted August 20, 2001 Share Posted August 20, 2001 Chris, Quote Link to comment Share on other sites More sharing options...
The_Shark Posted August 20, 2001 Share Posted August 20, 2001 Chris, I didn't word my post correctly. I don't actually work for Newark. We use them for a vendor, I'm in charge of four production cyclotrons (particle accelerators) for a company that make nuclear medicines. I'll be happy to fax you what I have in mind for models of the fans. The_Shark Quote Link to comment Share on other sites More sharing options...
Tom Adams Posted August 20, 2001 Share Posted August 20, 2001 I'm not a thermal engineer, but I did stay at a Holiday Inn a couple of weeks ago. Maybe I'm over-simplifying things here, but if heat is not a factor for the other solid state components (the DVD player and the Denon), then why not put the tubes at the bottom of the stack and let thermodynamics do the rest. The other thing that's not known here is what exactly are the heat loads we're talking about. I mean, how can you determine CFM extraction requirements when you don't have data? And isn't it possible that you really don't have a problem? If it were me, I'd take some Tylenol PM (so you don't wake up starring at the ceiling at 2:30am ), forget about fans & such, install the equipment, play the system and monitor the heat. Then determine if there's really a problem. The Cornwalls don't need much power - therefore the tubes won't be producing *that* much heat, relatively speaking. Remember too that the manufacturers recommendation of one foot is to save his butt and if they design like we do, their safety margin is at least 1.5. Anyhow....just my ramblin' thoughts. Tom Adams Quote Link to comment Share on other sites More sharing options...
The_Shark Posted August 20, 2001 Share Posted August 20, 2001 Tom, Vacuum tubes are designed to dissipate / operate at a maximum wattage as with most electronic components. The problem with vacuum tubes as compared to solid state electronics is that they generate much more heat that solid state components. The heat a vacuum tube generates when operating in a non-ventilated enclosure can build very quickly. The problem is that the wattage a tube can handle is based on proper cooling to the tube whether it be water or air. If the tube is operating in a higher ambient temperature the maximum wattage rating is derated and effectively lower. If you look at a spec sheet for almost any power tube there is a power rating curve based on temperature. We have a problem at my work with a RF amp that is designed to operate at 40 kw but the water cooling system is under rated, so we only have cooling for 30 kw. In the summer we lose a couple of tubes due to warmer air temps where the amp is. The tubes maximum wattage is lowered because it can't transfer enough heat. Tubes should always be operated within its design tolerances or you can significantly shorten the life of the tube or cause other peculiarities. I'm not familiar with the exact specs on this amp, but I'm sure the 1 foot recommendation is for a non-enclosed enviroment. But based on other amps (100w or greater) I've seen ventilation would be prudent. The_Shark Quote Link to comment Share on other sites More sharing options...
Tom Adams Posted August 20, 2001 Share Posted August 20, 2001 Ohhhh...ok. Thanks The_Shark for clearing that up. As you can clearly see, I'm not a "tube" man. However, I still contend that Chris needs to asses what he has to deal with before he runs out and starts buying stuff. Assuming the worst case, where he does indeed have to deal with forced cooling in order to achieve proper cooling of the amp, Chris would still need to know what his max temps were and what flow he'd need in order to pull the air temp down to a safe level. Hey - didn't I say I was over-simplifying? Now I'm suggesting doing a mass flow calculation. Sheesh!! Tom Adams Quote Link to comment Share on other sites More sharing options...
Colin Posted August 20, 2001 Share Posted August 20, 2001 I had my Dynaco EL-84 tube amps out in the open with and without their cages. I had my Paramour 2A3 amps both in the entertainment center, with the glass doors open, and now out in the open (bottom shelf of the TV rack). They run cooler in the open, but no significant differences in sound. They sit on a paving stone to dampen vibrations and this may act immeasurably as a heat sink. I would get as much air around the tubes as possible. One square foot is not going to be cool enough. You will feel the heat closing in around the amps, unless the air is pushed past them. I would drill a hole in the back or top of the cabintes and sneak a muffin fan near each one. The cooler the better. ------------------ big old Cornwalls, Bottlehead 2A3 Paramour tube amps, Dynaco series II tube pre-amp, Rotel CD player, KSW200 & LF10 subs Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted August 20, 2001 Author Share Posted August 20, 2001 Thanks, everybody. FYI, I've got one of the two Anthems in a 3' x 3' x 2' cabinet now (by itself), and when my 2 year old comes by and closes the cabinet doors, it takes about 2 minutes for that space to get warm and toasty (95+ degrees). I think in 30 minutes, I could do some serious cooking in there. Based on Shark's input, I am definitely going to have to put one or two fans in that cabinet. It appears that directly venting them on the left side of the cabinet throw the common wall (into the garage) will be the slickest solution. In the summer, it will vent temp controlled house air (central AC) into the garage, and in the winter, it will send warm air ... I'll also wall switch those fans so they can be shut off as needed (beyond the toddler's reach . I'll document this project with digital pix and put them up here in a few weeks for anyone interested to see. Shark's working on fan selection to help me out. Believe it or not, there are 1000's of fans to chose from. Cabinet size is roughly 45" H by 29" W by 24" D. Planning on making the shelves 20" or so deep to allow for airflow on each side of the shelf when the doors are closed, but at 16 to 20 cubic feet of air, a good muffin fan (still don't understand the derivation of the term "muffin" for a fan ) should exchange the air 4 to 5 times a minute. That ought to do it What would we do without these projects? My wife lovingly reminded me of how simple life was when we had Bose cubes ... but even she comments on the sound of the five Klipsch-a-crankin'. Nothing in the world like it. ------------------ Klipsch 1968 ALK Cornwall "II"s (LF/RF) ALK Belle Klipsch (Center) Klipsch Heresy (RR/LR) Klipsch KSW-12 sub Sonic Frontiers Anthem AMP1 (driving Cornwalls) Sonic Frontiers Anthem AMP1 (driving Heresy's) McIntosh MC-30 (driving Belle) Denon AVR-4800 Toshiba SD-3109 DVD Quote Link to comment Share on other sites More sharing options...
MacKlipsch Posted August 25, 2001 Share Posted August 25, 2001 I have my tubes in a cabinet with glass doors that I prop open when in use. Seems to work fine. Going to pick up a thermometer to set on the shelf to monitor. What would be the acceptable range in air temperatures? Quote Link to comment Share on other sites More sharing options...
WMcD Posted August 25, 2001 Share Posted August 25, 2001 Good question. "In the days of my youth I was . . . ." In the old days, tube stuff enclosures were generally warm to the fingers, except for the bottles themselves. They do get hot. This is somewhat reverse logic. What is "hot" to the rest of the components? I think you'll find that an ambient temperature in the box of 120 degrees F. (our common scale) is very warm to the fingers. That might well be a cut off. Basically, I've never seen a situation where the chassis is tolerably warm to finger touching, and anyone saying "There is something wrong, it's running hot." If you have the manual for the amp, you might find that performance is rated up to 120 degees or the like. Gil Quote Link to comment Share on other sites More sharing options...
Marvel Posted August 25, 2001 Share Posted August 25, 2001 Chris, Here is another thing to consider. If you put fans at the bottom, to pull air into the cabinet, make a provision for some kind of air filter material. This way, you have positive air pressure in the cabinet, and will have air coming out around all the gaps, glass doors, etc. If you have fans at the top, sucking air out, that air will come through all of those same gaps, pulling dust into the cabinet. At the college where I work doing computer support, our grounds dept. had a computer that you could actually dump dirt out of when you opened it up. We had the carpentry shop build a cabinet for it, with a slot in the back to run cables out, with a fan/filter pushing air in. After months of running, there is almost no dust in the computer (or cabinet). We just used air filter material and have a clip of some kind to hold it over the fan (it is hidden in back, so it didn't have to be super neat). This way neither the front door to the cabinet nor the slot for cables had to be sealed. Most computers only have the fan in the power supply, pulling air through the computer case and exhausting out the back, creating negative air pressure in the case. They pull dust into the floppy drive and case, causing buildup on the cpu and other boards. Not very healthy for them at all. Bruce Quote Link to comment Share on other sites More sharing options...
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