The situation is that you not only have to extract hot air out of the case, but cool air also has to come into the case.
So if you extract hot air from one side, you have to introduce fresh air from the other one and you will still have to evaluate what kind of pressure will be created inside the amp (positive, neutral or negative) just like it happens inside a computer case.
May be of interest, https://www.neweggbusiness.com/smartbuyer/over-easy/pc-cooling-how-to-set-up-computer-case-fans/
OK, I've been doing some experiments. Because of the present set up, I begun by pulling air out from the top. It was just much easier.
(Note: for our international friends, specifically for someone living in the area once controlled by Tito, I'm taking metric measurements).
I've started with the current rack, I plan on reassembling it tomorrow with the four 10" shelves becoming 12". (*) That will increase the space above the 5U amps to about just under 3 inches. The feet of the chassis have about 3/4". Room temp today was 74F, about 22C, I think.
I got a couple of lap top coolers, one with a single fan, another with two fans. I also got a remote temp sensor.
The Sissy was most convenient, on a 9" shelf, the 4U chassis has just enough space, and a bit more, to fit the lap cooler.
So, today I set up the sensor above the Sissy SIT, put the the cooler on over it, turned on the system and after about 45 minutes, I measured a consistent 47C. I did not measure the heat sinks, but from previous measurements they clocked in under 55C consistently. I did not compare, today, the "laser" temp measuring gun with the newly acquired sensor... one thing at a time.
Anyhow, after turning on the fans, which are barely audible from three feet away, not at all from even five feet.. about another hour the temp had settled to 39C.
That's an 8C difference.
That's pulling air out... in a very tight vertical space. The heat sinks are in the open, so I'm not too worried about that.
I plan on taking more extensive measurements in the newly reconfigured rack... with the Sissy and the A2s with the "standard" ventilated vents. Will use the two fan and the single fan coolers. Depending on what I find out, I might use the original, now "spare" covers, to make a hole in the middle and install a low speed 6 inch fan that shoots either in or out. We'll see, but the laptop coolers are nice, cheap and you can turn off the lights...
My hope is that I can achieve case internal temps for the 252 Macho SIT, 5U/400, in a 12" shelf around 50C.
(*) OK, I didn't say I was gonna measure length in metric... bite me...
(Note: for our international friends, specifically for someone living in the area once controlled by Tito, I'm taking metric measurements).
I've started with the current rack, I plan on reassembling it tomorrow with the four 10" shelves becoming 12". (*) That will increase the space above the 5U amps to about just under 3 inches. The feet of the chassis have about 3/4". Room temp today was 74F, about 22C, I think.
I got a couple of lap top coolers, one with a single fan, another with two fans. I also got a remote temp sensor.
The Sissy was most convenient, on a 9" shelf, the 4U chassis has just enough space, and a bit more, to fit the lap cooler.
So, today I set up the sensor above the Sissy SIT, put the the cooler on over it, turned on the system and after about 45 minutes, I measured a consistent 47C. I did not measure the heat sinks, but from previous measurements they clocked in under 55C consistently. I did not compare, today, the "laser" temp measuring gun with the newly acquired sensor... one thing at a time.
Anyhow, after turning on the fans, which are barely audible from three feet away, not at all from even five feet.. about another hour the temp had settled to 39C.
That's an 8C difference.
That's pulling air out... in a very tight vertical space. The heat sinks are in the open, so I'm not too worried about that.
I plan on taking more extensive measurements in the newly reconfigured rack... with the Sissy and the A2s with the "standard" ventilated vents. Will use the two fan and the single fan coolers. Depending on what I find out, I might use the original, now "spare" covers, to make a hole in the middle and install a low speed 6 inch fan that shoots either in or out. We'll see, but the laptop coolers are nice, cheap and you can turn off the lights...
My hope is that I can achieve case internal temps for the 252 Macho SIT, 5U/400, in a 12" shelf around 50C.
(*) OK, I didn't say I was gonna measure length in metric... bite me...
Attachments
Last edited:
Since the cooler is not being sealed in any way, but simply sitting down, it's good to know that you've achieved some interesting results by simply dissipating the hot air escaping from the entire lid of your amp and from the slits on it.
However, if the cooler is not sealed then the air that comes out of the slits is almost exactly what comes out normally and furthermore the cooler will also suck air from all the lateral space, which means poor cooling efficiency.
If you place a single fan (on the amp cover or elsewhere) you will get most likely a negative pressure inside your amp and then all the smallest openings in the case will suck-in air at high pressure because the fan itself will force it out of any existing holes or slits.
All existing openings will soon be covered in dust and will shortly affect the effectiveness of the cooling.
Unless your amp has a surface area resulting from the sum of all existing openings and slits that allow an adequate volume of incoming air flow equal to that of extraction.
In any case, filtering the air remains an essential factor.
By the way, I just imagined to calculate the free surface of all the holes (compared to the fan's air volume flow) of an internal base (or even of side bulkheads) like this,
which in any case if not filtered (the holes) from the outside would quickly fill with dust due to aforesaid negative pressure.
However, if the cooler is not sealed then the air that comes out of the slits is almost exactly what comes out normally and furthermore the cooler will also suck air from all the lateral space, which means poor cooling efficiency.
If you place a single fan (on the amp cover or elsewhere) you will get most likely a negative pressure inside your amp and then all the smallest openings in the case will suck-in air at high pressure because the fan itself will force it out of any existing holes or slits.
All existing openings will soon be covered in dust and will shortly affect the effectiveness of the cooling.
Unless your amp has a surface area resulting from the sum of all existing openings and slits that allow an adequate volume of incoming air flow equal to that of extraction.
In any case, filtering the air remains an essential factor.
By the way, I just imagined to calculate the free surface of all the holes (compared to the fan's air volume flow) of an internal base (or even of side bulkheads) like this,
which in any case if not filtered (the holes) from the outside would quickly fill with dust due to aforesaid negative pressure.
there are some simple but logical reasons why I made my Babysitter as I did
even if al my observations are strictly with amp in free space practically (side and top clearances practically non existing), I believe it's still best overall solution***, without resorting to Krell KSA50 or - even better - Peavey CS400 way of doing it
now, I tried semi-step - introducing sponge strips in between Babysitter plate and base of amp itself, to inject air directly to inside of amp through bottom slots; besides dust worry (yeah, years of cleaning PCs gives you phobia) I did found better results of leaving it simplest possible - some air is going inside through slots, some air is going in general heatsinks direction, result being - more air all around amp, thus overall lower temperature
I had my share of obsessing (with actual subject), leaving it now to you (anyone interested), I'm up to new, uncharted, obsessing subjects territory
***speaking strictly of assisting with some silent air flow, not really forced air cooling, as primary approach
now, as tonyee posted pic for first time, and I'm seeing shelf is actually open at sides - proper base-situated Babysitter is all what's needed; under condition that there is still few thumbs of clearance above
normal thumbs, not whiskey ones
even if al my observations are strictly with amp in free space practically (side and top clearances practically non existing), I believe it's still best overall solution***, without resorting to Krell KSA50 or - even better - Peavey CS400 way of doing it
now, I tried semi-step - introducing sponge strips in between Babysitter plate and base of amp itself, to inject air directly to inside of amp through bottom slots; besides dust worry (yeah, years of cleaning PCs gives you phobia) I did found better results of leaving it simplest possible - some air is going inside through slots, some air is going in general heatsinks direction, result being - more air all around amp, thus overall lower temperature
I had my share of obsessing (with actual subject), leaving it now to you (anyone interested), I'm up to new, uncharted, obsessing subjects territory
***speaking strictly of assisting with some silent air flow, not really forced air cooling, as primary approach
now, as tonyee posted pic for first time, and I'm seeing shelf is actually open at sides - proper base-situated Babysitter is all what's needed; under condition that there is still few thumbs of clearance above
normal thumbs, not whiskey ones
no worries
I didn't got it in that way
though, hearing different opinions in many cases leads to learning something, so feel free to aim, whenever you see "at"
anyway - my Ego is so big that it can't be offended
The same here.
I feel really free like this, even if I've noticed that sometimes my words, even if written, are received differently from my intentions and if it's true that it's not worth clarifying with everyone, it's also true that with some other it's definitely worth.
I didn't even think that you might be offended, but please be careful what you believe...
https://www.simplypsychology.org/psyche.html
Wow.. thanks.... my ego is getting so big that I will need a big TonySitter.
The house has air filters so we don't have much dust and all I'm trying to do is to move just enough air through the cavity. The Sissy SIT has no issues and the A2s have had no issues in the past ( mono blocks ).... However, I will push forward in the interest of longevity... Keep it at 55C.
The goal is to keep the Macho SIT at a comfy 55F internal cavity.... no more and no less.
The reason I have not yet done the Babysitter push-from-below design is lack of space. Once I get the new rack up and running then I'll start taking more serious measurements. The final goal is to have keep the top shelves clear because I want to put a 34" display there so I can record with the RME ADI2 while I keep Mister Macho from self immolating as if it were in a Tristan and Brunhilde Saga... I want to hear both channels of Can Can..... not just Can ......
It sure looks like the putative Big Baddah Bing is gonna require a big case and likely some low volume air flow. You think we can go with liquid airflow and an external radiator?
Also, note that the Doughnut Man is putting BIG heastsinks on several of the internal transistors.... gotta keep Q1 from burning up again and R46/47 from leaving nice pyres behind. Plus cap residue... Oy... it was an exciting listening session... Smoke on the water... and fire in the living room...
The house has air filters so we don't have much dust and all I'm trying to do is to move just enough air through the cavity. The Sissy SIT has no issues and the A2s have had no issues in the past ( mono blocks ).... However, I will push forward in the interest of longevity... Keep it at 55C.
The goal is to keep the Macho SIT at a comfy 55F internal cavity.... no more and no less.
The reason I have not yet done the Babysitter push-from-below design is lack of space. Once I get the new rack up and running then I'll start taking more serious measurements. The final goal is to have keep the top shelves clear because I want to put a 34" display there so I can record with the RME ADI2 while I keep Mister Macho from self immolating as if it were in a Tristan and Brunhilde Saga... I want to hear both channels of Can Can..... not just Can ......
It sure looks like the putative Big Baddah Bing is gonna require a big case and likely some low volume air flow. You think we can go with liquid airflow and an external radiator?
Also, note that the Doughnut Man is putting BIG heastsinks on several of the internal transistors.... gotta keep Q1 from burning up again and R46/47 from leaving nice pyres behind. Plus cap residue... Oy... it was an exciting listening session... Smoke on the water... and fire in the living room...
View attachment 1230506
@Zen Mod
Thank you for your interesting and appreciated in-depth analysis.
Also, sorry if I forgot to add @tonyEE to my previous post which was absolutely not aimed at you or your creation, but at his cooling experiments.
Edit to add: assuming you replied to me...
Remember the cartoon Tin Tin... where Captain Haddock has been told by his doctor to slow down his whiskey drinking... "only two fingers"..... so of course, he measures his fingers vertically.....
Ok, ready for Phase two.... amp racks are rebuilt, the bottom shelves are now a full 12".
The A2s are on the bottom shelf, the Sissy on the next up, to the right... the Macho SIT will go next to it.
Got two different lap top coolers and three of them temp sensors.
Time to wire the rack and start burning things up.... ( a metaphor in this case, hopefully not the real thing.... ).
Oh, in case you wonder, the boxes under the rack keep the robot vacuum from messing with the wiring.. besides, we like Pink Flamingos.
The A2s are on the bottom shelf, the Sissy on the next up, to the right... the Macho SIT will go next to it.
Got two different lap top coolers and three of them temp sensors.
Time to wire the rack and start burning things up.... ( a metaphor in this case, hopefully not the real thing.... ).
Oh, in case you wonder, the boxes under the rack keep the robot vacuum from messing with the wiring.. besides, we like Pink Flamingos.
Attachments
Yeah, that's an European Kenwood KT-9900. It has the dual voltage power supply and the very nice finish... and then the CJ ET3SE. You don't see the turntable, that's on its own Target Rack.. and you don't see the fancy Burson op amps.. The DIYstore carries them...
The hard part is keeping the flamingos away from the speakers.
The hard part is keeping the flamingos away from the speakers.
Oh, don't you listen to the radio?
BTW, I miss the knob in the preamp. It does have remote and local buttons, but no knob. OK, gonna do the wiring up in the afternoon.
Baseline measurements will be static, with no forced air. I still don't have the Macho Amp back but I hear it's burning in nicely with the larger heatsinks in the internal components.
BTW, I miss the knob in the preamp. It does have remote and local buttons, but no knob. OK, gonna do the wiring up in the afternoon.
Baseline measurements will be static, with no forced air. I still don't have the Macho Amp back but I hear it's burning in nicely with the larger heatsinks in the internal components.
Radio, all the time
practically most of time FM, just one station, 24/7 Cultural program - Radio Belgrade 2(3)
OK, I'm cheating , sometimes web radio, Jazz, any station without adds
have ReVox A76, both in Workshop and in Boss's living-room
and little pet - Quad FM3, right under PC screen foot
not counting others, on shelves
practically most of time FM, just one station, 24/7 Cultural program - Radio Belgrade 2(3)
OK, I'm cheating , sometimes web radio, Jazz, any station without adds
have ReVox A76, both in Workshop and in Boss's living-room
and little pet - Quad FM3, right under PC screen foot
not counting others, on shelves
I guess we're off subject... until either I put up some numbers or someone else gets the Mas Caliente Macho on a shelf.
BTW, I was looking at active cooling... not with this amp... but, but... I'm surprised the Audio World is so far behind with cooling schemas...
KTWV-FM 94.7 The WAVE.... cool jazz... calms my nerves in the background.
Otherwise I listen to Tidal HiFi streams... not bad either.
The KT9900 is a fairly recent purchase, got a good price from a guy down in San Diego... surprisingly over eBay. (*) It's in very good shape and the guy is an expert on FM tuners with reasonable prices and Make-Me-An-Offer options... so I paid $390 including shipping. Tuner is aligned, electronics are in great shape, although I'm still gonna have it gone once (and twice) over by the guy who has done my vintage units.
KT9900 is the Euro/Global cousin of the KT8300. The latter has the standard NA silver with black lettering. Electrically they are identical. Every tuner must have at least three meters!
No need to introduce the Conrad Johnson ET3SE line stage. Got it used. Still under warranty... No need for the phono stage since I have the uber fancy version of the P2. Planning on the P3.
We'll see how hot this thing gets.
(*) I take perverse joy at dealing with those eBay sellers that are ignorant and/or greedy and ask for Out Of This Universe prices. My favorite was the one that was asking $24,000 for his pair of Aleph 2 amps. I asked if he'd done a typo... essentially his rationale for asking 10 times the going price was that "these are my amps so they are special"... Then you got the prices on old mid 70s Marantz receivers... and Superscope/Radio Shack stuff...
BTW, I was looking at active cooling... not with this amp... but, but... I'm surprised the Audio World is so far behind with cooling schemas...
KTWV-FM 94.7 The WAVE.... cool jazz... calms my nerves in the background.
Otherwise I listen to Tidal HiFi streams... not bad either.
The KT9900 is a fairly recent purchase, got a good price from a guy down in San Diego... surprisingly over eBay. (*) It's in very good shape and the guy is an expert on FM tuners with reasonable prices and Make-Me-An-Offer options... so I paid $390 including shipping. Tuner is aligned, electronics are in great shape, although I'm still gonna have it gone once (and twice) over by the guy who has done my vintage units.
KT9900 is the Euro/Global cousin of the KT8300. The latter has the standard NA silver with black lettering. Electrically they are identical. Every tuner must have at least three meters!
No need to introduce the Conrad Johnson ET3SE line stage. Got it used. Still under warranty... No need for the phono stage since I have the uber fancy version of the P2. Planning on the P3.
We'll see how hot this thing gets.
(*) I take perverse joy at dealing with those eBay sellers that are ignorant and/or greedy and ask for Out Of This Universe prices. My favorite was the one that was asking $24,000 for his pair of Aleph 2 amps. I asked if he'd done a typo... essentially his rationale for asking 10 times the going price was that "these are my amps so they are special"... Then you got the prices on old mid 70s Marantz receivers... and Superscope/Radio Shack stuff...
OK. some preliminary numbers with the SissySIT.
The amp has about 1 1/2 inches below and about 3 1/2 inches above. The sides are all open so the heatsinks have a place to vent. The left ( from the front ) heatsink faces other an A2 amp about four inches away - turned off for these tests. The amp covers are the standard Modushop Delux design, with three rows of cooling slots on either side of the plate.
I used two laptop coolers, one with a single large fan, another with two smaller fans. the coolers were set on top of the amp, centered front to back and side to side. Tried the highest/lowest speed settings. The highest setting for the two fan affair was barely audible from 12 feet away when there was no signal Otherwise you didn't hear at all.
For these tests, three temp sensors were used: (1) for the room temp; (2) for the left heat sink 2/3rds of the way back, towards the SIT proper and (3) over one of the cooling slots about middle of the way over one of the amp boards. For all measurements, I allowed at least 30 min for the sensors to stabilize. I also took measurements with the FM tuner playing rather softly in the background and with some real music.
The bottom line is that with plain static cooling, I think this rack configuration allows the SissySIT to run cool. It's about 5C less than it was with the previous rack which only allowed about 1 inch below and 2 inches above.
What surprised me the most was how sensitive the heat sinks were to the amp cavity cooling down. That means the side heat sinks do heat up the internals of the amp... perhaps a thermal barrier between the inside of the side heat sinks and the amp cavity would help shed the heat to the outside better?
I'll take more measurements today... but here's some...
Notice too how the 2 Fan Hi managed to take out almost 6C from both the cavity and the heat sinks.
The amp has about 1 1/2 inches below and about 3 1/2 inches above. The sides are all open so the heatsinks have a place to vent. The left ( from the front ) heatsink faces other an A2 amp about four inches away - turned off for these tests. The amp covers are the standard Modushop Delux design, with three rows of cooling slots on either side of the plate.
I used two laptop coolers, one with a single large fan, another with two smaller fans. the coolers were set on top of the amp, centered front to back and side to side. Tried the highest/lowest speed settings. The highest setting for the two fan affair was barely audible from 12 feet away when there was no signal Otherwise you didn't hear at all.
For these tests, three temp sensors were used: (1) for the room temp; (2) for the left heat sink 2/3rds of the way back, towards the SIT proper and (3) over one of the cooling slots about middle of the way over one of the amp boards. For all measurements, I allowed at least 30 min for the sensors to stabilize. I also took measurements with the FM tuner playing rather softly in the background and with some real music.
The bottom line is that with plain static cooling, I think this rack configuration allows the SissySIT to run cool. It's about 5C less than it was with the previous rack which only allowed about 1 inch below and 2 inches above.
What surprised me the most was how sensitive the heat sinks were to the amp cavity cooling down. That means the side heat sinks do heat up the internals of the amp... perhaps a thermal barrier between the inside of the side heat sinks and the amp cavity would help shed the heat to the outside better?
I'll take more measurements today... but here's some...
| Room C | Heat sinks C | Top Lid C | |
| Idle, no Fan | 25.4 | 50.5 | 41.1 |
| 1 Fan, lo | 25.4 | 49.7 | 40.5 |
| 1 Fan, hi | 25.7 | 49.6 | 40.1 |
| 2 Fan, lo | 25.8 | 46.5 | 40.1 |
| 2 Fan Hi, | 25.6 | 45.4 | 34.9 |
| 2 fan Lo, | 26.2 | 47.5 | 37.8 |
| 2 fan Lo, louder music | 27.2 | 48.5 | 39.2 |
Notice too how the 2 Fan Hi managed to take out almost 6C from both the cavity and the heat sinks.
Last edited: