Heat pipe cooling in power amps

[Doodski]

Here are images of a heat pipe assembly used on 1980s, 35w/ch Technics SU-V303 integrated amplifier. The orientation of the heat pipe clamping surface is not as you will require but I think this might give you some ideas about how to design the clamping assembly so that you have a flat, machined with tight clamping force surface that will mate with the power devices that you need to cool. If you can fabricate a soft malleable sheet metal that can go around the heat pipe, use that to clamp to a easily available thin flat metal stock like aluminum and then have that flat stock mate with the power devices using thermal paste at the PCB by using screws and locking nuts that you will have a effective clamping assembly that can conduct a lot of thermal energy.
You could even find a old Technics SU-V303 and use the heat pipe and assembly and adapt it to fit your PCB layout assembly technique.
NOTE: There are other brands that used heat pipes and they may have a heat pipe cooler assembly that is better than the Technics.

 

[Doodski]

Here are flat heat pipe and heatsink assemblies intended for flat PCB direct mounting. They closely resemble a video card heat pipe cooler.

https://www.aliexpress.com/item/1005004104043032.html?src=google&src=google&albch=shopping&acnt=272-267-0231&slnk=&plac=&mtctp=&albbt=Google_7_shopping&gclsrc=aw.ds&albagn=888888&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005004104043032&ds_e_product_merchant_id=108123907&ds_e_product_country=CA&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=20695954287&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gclid=CjwKCAjw7-SvBhB6EiwAwYdCAS9AeN_ejkzwK-AyUY7QXswE4nPxNx0S0xo5YSbX1XebclZuHDnqZhoC2ccQAvD_BwE&aff_fcid=8c7b1743c73046b2a34b4e8d99141bef-1710843442927-02656-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=8c7b1743c73046b2a34b4e8d99141bef-1710843442927-02656-UneMJZVf&terminal_id=1f0a117aac14427daf6bd29b98849e00&afSmartRedirect=y

https://www.aliexpress.com/item/1005004816950812.html?spm=a2g0o.detail.1000023.9.7528f9hHf9hHOQ

https://www.aliexpress.com/item/1005006282876081.html?spm=a2g0o.detail.pcDetailBottomMoreOtherSeller.4.7528f9hHf9hHOQ&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.40000.326746.0&scm_id=1007.40000.326746.0&scm-url=1007.40000.326746.0&pvid=068de916-fe19-44d7-8a70-65422a88a73f&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.40000.326746.0,pvid:068de916-fe19-44d7-8a70-65422a88a73f,tpp_buckets:668%232846%238113%23607&pdp_npi=4%40dis%21CAD%2121.25%2114.87%21%21%2115.33%2110.73%21%402101e7a317108437488215078ee331%2112000036600217322%21rec%21CA%21%21AB&utparam-url=scene%3ApcDetailBottomMoreOtherSeller%7Cquery_from%3A

https://www.aliexpress.com/item/1005005918781186.html?spm=a2g0o.detail.pcDetailBottomMoreOtherSeller.9.7528f9hHf9hHOQ&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.40000.326746.0&scm_id=1007.40000.326746.0&scm-url=1007.40000.326746.0&pvid=068de916-fe19-44d7-8a70-65422a88a73f&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.40000.326746.0,pvid:068de916-fe19-44d7-8a70-65422a88a73f,tpp_buckets:668%232846%238113%23607&pdp_npi=4%40dis%21CAD%2132.64%2115.22%21%21%2123.55%2110.98%21%402101e7a317108437488215078ee331%2112000034850073846%21rec%21CA%21%21AB&utparam-url=scene%3ApcDetailBottomMoreOtherSeller%7Cquery_from%3A

 

[wwenze]

I have seen power supplies use very thick thermal pads to cross an air gap. Think of tofu or youkan.

Heatpipe kits should come with a block with groove to slide your heatpipe into.

And then there's flat heatpipes which are everywhere in laptops but usually those are soldered... Flat heatpipes are much harder for the consumer to bend, unlike round ones.

 

[MCH]

I have seen power supplies use very thick thermal pads to cross an air gap. Think of tofu or youkan.

Heatpipe kits should come with a block with groove to slide your heatpipe into.

And then there's flat heatpipes which are everywhere in laptops but usually those are soldered... Flat heatpipes are much harder for the consumer to bend, unlike round ones.

Yes, I want to avoid any bending, it seems to be very difficult + I don't have the tools. But with the design I have in mind, straight pipes are fine

 

[Doodski]

With this vertically oriented cooler it could be thermal epoxy secured to the power devices that are being cooled. No screws required through the PCB. Multiples may be used for more thermal energy dissipation.

https://www.amazon.ca/Thermalright-heatsink-Double-Sided-Silicone-Computer/dp/B0BPGMRTSW/ref=asc_df_B0BPGMRTSW/?tag=googleshopc0c-20&linkCode=df0&hvadid=579070369590&hvpos=&hvnetw=g&hvrand=8423726005307786867&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9001365&hvtargid=pla-2070606256468&mcid=b4953a6d58293174b276bdd0f37338fa&th=1

 

[wwenze]

Guys, i believe it is very feasible.
Here is a simulation of how the modules would look like with the BOM of TPA3255 eval board. This contains all the parts needed for balanced input and stereo and bridged operation and also the PFFB net and a radiator with a 4cm fan. I left out the 12V voltage regulators (I would use a USB power delivery chip) and microcontroller (for fan control, amp restart and master/slave board controls etc) that would go in a different board. Each module is 11x7 cm. The idea would be to put other two boards on top (all bulky components pointing outwards) for a total of 4 heat pipes (represented by the yellow lines. Each amp would have one heat pipe for the amp chips and another one to the ground plane somewhere around the inductors/output stage.
I think the whole 8 channels amp could fit a ca. 22x13x8 cm enclosure. Ok, a bit more than half a cigar box, but still a smallish cigar box

I might be even go ahead and do it, but it won't be a cheap project, i calculate roughly 150-200 eur + PSU...

View attachment 357350

Ahh... I see...

Heatpipes are quite the straightforward choice.

But... do you really have to do it this way? Heatpipes only shift heat from one place or another, you still need the same amount of radiator. Heck, maybe even a little bit more, due to the thermal resistance of the heatpipes. (Although smart heatpiping usually use the heatpipe to also reduce the thermal resistance of the radiator)

Your plan is to have a thick radiator block on the right side and the amp on the left, why not have the amps on the bottom side and the heatsinks on the top?

 

[MCH]

Ahh... I see...

Heatpipes are quite the straightforward choice.

But... do you really have to do it this way? Heatpipes only shift heat from one place or another, you still need the same amount of radiator. Heck, maybe even a little bit more, due to the thermal resistance of the heatpipes. (Although smart heatpiping usually use the heatpipe to also reduce the thermal resistance of the radiator)

Your plan is to have a thick radiator block on the right side and the amp on the left, why not have the amps on the bottom side and the heatsinks on the top?

I don't, I don't even need a 8 channel amp I don't even have 8 speakers . I just want to experiment with the concept and find it a cool project, that I believe would find a better use when the parts to cool difficult to cool by other means.
(+I need to find something to do with the 3D printer or I will run out of excuses to keep it home)

 

[somebodyelse]

Streacom sell spare heatpipe mounting blocks for their PC cases, with models for round and flattened heatpipes. https://shop.streacom.com/collections/accessory-kits-cooling

 

[MCH]

Streacom sell spare heatpipe mounting blocks for their PC cases, with models for round and flattened heatpipes. https://shop.streacom.com/collections/accessory-kits-cooling

 

[Rick Sykora]

Might want to look at the Vera amp review as it appears to be a (more) contemporary use of heat pipes.

…or whatever this is… https://www.audiosciencereview.com/...p400-1000-review-amplifier.30192/post-1060796

 

[somebodyelse]

Might want to look at the Vera amp review as it appears to be a contemporary use of heat pipes.

…or whatever this is… https://www.audiosciencereview.com/...p400-1000-review-amplifier.30192/post-1060796

Seems to be an aluminium heat spreader or sink to help cool the coils, plus ducts for the Noctua fans if it gets hot enough to need them. The coils don't normally have any heatsinking on the Hypex amps, but others have also shown they get quite hot so require a case with good ventilation. I don't see a heatpipe here.

 

[Rick Sykora]

Seems to be an aluminium heat spreader or sink to help cool the coils, plus ducts for the Noctua fans if it gets hot enough to need them. The coils don't normally have any heatsinking on the Hypex amps, but others have also shown they get quite hot so require a case with good ventilation. I don't see a heatpipe here.

Yes, I did not include the full amp picture. That one appears to utilize some piping. Perhaps @Armand can explain the differences between the pics.

 

[sarieri]

I measure around 65 celcius on the hottest spot of NCx500. Hypex manual said 2cm minimum Heatsink. I have no idea how that's gonna help with the temp.

 

[somebodyelse]

Yes, I did not include the full amp picture. That one appears to utilize some piping. Perhaps @Armand can explain the differences between the pics.

Do you mean posts #9 and #69? Reflection of lighting on the milling toolmarks on the aluminium block make it look a bit like tubes. You can see the copper tone in some of the other reflections on the caps, mounting and casework on the far side.

 

[Rick Sykora]

Do you mean posts #9 and #69? Reflection of lighting on the milling toolmarks on the aluminium block make it look a bit like tubes. You can see the copper tone in some of the other reflections on the caps, mounting and casework on the far side.

Yes, #9, but more to the point for the OP, the Vera is a Class D amp with a bend towards better heat dissipation.

One big diff is the Vera already has the NC500 heat spreader. A heat pipe is one potential solution, it may not be the best one. I would suggest the better approach is to ensure whatever TI recommends for their chips is achieved and then might get fancy with heat pipes or other techniques.