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Yes, that’s the best.
I did a ‘passive’ version using chimneys to create vertical airflow up through the centre.
https://www.diyaudio.com/forums/sol...ion-jlh-69-class-amplifier-2.html#post4264974
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Fans arrived - 92mm holes cut in the base, this morning (done by my friendly metal man).
Attached is a pic of one fan installed on its rubber mounts, with Dell CPU cooler above ... also showing the second cut hole.
I'm not going to use the PWM controller - instead I'll:
1. use a 10 or 12w res to drop the voltage from the 20v SLB +ve rail to 12v, and
2. make use of the 'Low Noise Adaptor' cable, which lowers fan speed from 2200rpm to 1700rpm.
Andy
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Thank you, Hugh.
Yes, with Vunce's input it should solve the Class A thermal problem. 🙂
Andy
Your setup looks real good Andy! Your AN should run cool as a cucumber now 😀
Just double check if the fans will operate without a PWM controller.
Just double check if the fans will operate without a PWM controller.
AN SMPS
I thought I would innovate using SMPS for my AN build. So I did.
Great sound, especially bass. No hum, no hiss between tracks. Positive WAF.
But after some listening time, the MeanWell SMPS fans kicked in: a different story. Loud!
My preliminary bench tests were not long enough to start the fans and I thought they would never turn on….
Well, it’s time to start building a proper linear PSU!
Jacques
I thought I would innovate using SMPS for my AN build. So I did.
Great sound, especially bass. No hum, no hiss between tracks. Positive WAF.
But after some listening time, the MeanWell SMPS fans kicked in: a different story. Loud!
My preliminary bench tests were not long enough to start the fans and I thought they would never turn on….
Well, it’s time to start building a proper linear PSU!
Jacques
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Nice work Jacques, before you give up try this: give the MW’s some more heatsink to mount to such as a large slab of aluminum and see if that prevents fans from coming on. You can also remove their case and aim a Noctua fan at them. Silent fans.
Thanks Jacques,
I have been thinking about the SMPS route as well. I have yet to build my AKSA, waiting for some semblance of normalcy to return.
Many years ago I built a Charlize from Diyparadise which is a TA2020 amp and used a 12Vdc SMPS out of a Kyocera Fax machine just to try and it worked really well and still does, it is "as quiet as a church mouse" and could I not find a fault which challenged my undeserved bias against the SMPS in audio.
I have been slowing putting together a list of the "support parts" like the wires, connectors and tools as suggested for the AKSA.
Andrew
I have been thinking about the SMPS route as well. I have yet to build my AKSA, waiting for some semblance of normalcy to return.
Many years ago I built a Charlize from Diyparadise which is a TA2020 amp and used a 12Vdc SMPS out of a Kyocera Fax machine just to try and it worked really well and still does, it is "as quiet as a church mouse" and could I not find a fault which challenged my undeserved bias against the SMPS in audio.
I have been slowing putting together a list of the "support parts" like the wires, connectors and tools as suggested for the AKSA.
Andrew
I think a 120mm Noctua PWM fan like this one should do:
Noctua NF-F12 PWM, Premium Quiet Fan, 4-Pin (120mm, Brown) https://www.amazon.com/dp/B00650P2ZC/ref=cm_sw_r_cp_api_i_UGfQEbV8VQTGC
You can drive both with an inexpensive PWM motor controller like this:
https://www.amazon.com/dp/B0752GMMPJ/ref=cm_sw_r_cp_api_i_WLfQEb449YKGN
These are available from China for about $4 if you want to wait 2 weeks.
Here is my idea of where to mount the fans after your remove the cases that the MW’s are in, in order to expose them to more airflow. Use the in-line speed reducer that the Noctuas came with. Play around with dip switches to get low velocity silent fan. There is a temp sensor even that set to say, 85C (whatever the internal fixed threshold points are) or so to make inside never gets too hot.
Noctua NF-F12 PWM, Premium Quiet Fan, 4-Pin (120mm, Brown) https://www.amazon.com/dp/B00650P2ZC/ref=cm_sw_r_cp_api_i_UGfQEbV8VQTGC
You can drive both with an inexpensive PWM motor controller like this:
https://www.amazon.com/dp/B0752GMMPJ/ref=cm_sw_r_cp_api_i_WLfQEb449YKGN
These are available from China for about $4 if you want to wait 2 weeks.
Here is my idea of where to mount the fans after your remove the cases that the MW’s are in, in order to expose them to more airflow. Use the in-line speed reducer that the Noctuas came with. Play around with dip switches to get low velocity silent fan. There is a temp sensor even that set to say, 85C (whatever the internal fixed threshold points are) or so to make inside never gets too hot.
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Or maybe you could create a duct ( cardboard is great) along the centre of the case encapsulating the power supplies with the fan at the rear exiting the case. Leave a few inches between the duct and the front panel. The air intake would be at the front of the duct and the bottom / top of the chassis has small louvers to allow air. You could just move the IEC connector / change the layout on the rear of the case. a "little" bit more work than X's suggestion though. I second the Noctua fan, they are very quiet and with the PWM set its in auto mode.
Andrew
Andrew
Hi X,
I'm afraid the built-in SMPS fans might still kick in, they seem to turn on at a relatively low temperature, even with the amp lid open. Apparently cutting the fan wires disables power output.
I was thinking instead of removing the original 60mm 12V fans and mount Noctua 92mm Flex on the outside of the SMPS case (with additional ventilation holes drilled) using the original two-pin connector & circuitry logic.
Power consumption is very comparable and ultra-low noise option is available with Noctua's this size.
Jacques
I'm afraid the built-in SMPS fans might still kick in, they seem to turn on at a relatively low temperature, even with the amp lid open. Apparently cutting the fan wires disables power output.
I was thinking instead of removing the original 60mm 12V fans and mount Noctua 92mm Flex on the outside of the SMPS case (with additional ventilation holes drilled) using the original two-pin connector & circuitry logic.
Power consumption is very comparable and ultra-low noise option is available with Noctua's this size.
Jacques
Replace the built in SMPS fans with Noctua NF-A6x25 FLX, 3-Pin Premium Cooling Fans (verify fit before).
If you still have issues after using Noctua or other quiet fan then try with the X cooling design or the duct.
If you still have issues after using Noctua or other quiet fan then try with the X cooling design or the duct.
Hi Andrew,
I checked that option also but the original fan is only 15mm deep. The case cannot accomodate 25mm thick internal fans.
Jacques
If you could move the relay board out from between the supplies you could then attach heatsinks with the fins running vertically and the area between the 2 supplies would act like a chimney, encouraging convective cooling of the heatsinks/chassis of the SMPS’s. I have used Noctua fans before, in an Aleph J build that has a chimney with 4 8” tall heatsinks mounted with the fins vertically. The fans are the 80mm size and the quietest that Noctua has in that size. I can still here them however, in my quiet listening room, although the noise is mostly that of the air flowing up through the heatsinks and out the top of the chassis. In that case I am trying o move about 200w out of the case. With your SMPS the heat load will be much lower, perhaps 20w would be a reasonable estimate. That is why I suggest that you could try a passive approach, first because no matter how quiet fans are they still create dust issues and a PWM fan controller is another source of potential noise near the audio circuitry. I have attached a couple of photos of the J with the heatsinks just visible under the chrome fan guards.
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Perhaps replace the fan with a resistive dummy load like 100ohm to prevent it from shutting down. I know, defeating built in thermal safety features. You need to make sure you have a good handle on the thermal systems and auto shutdowns.
I have completely disabled the fan on my cheap LED PSU (800w 48v) that seems to kick in even with the slightest use. It’s not even warm without a fan when used at average listening levels.