This is the same I've experienced! I added a couple of fan, each in front of the heatsink with a simple circuit that reads the temp of the heatsink and keeps the temp between about 42 and 48°C.
Without it the temperature is about 30°C over the ambient temp.
The fans are 12V and I connected them in series, just to reduce the speed and then the noise.
I don't really want to fit fans-I don't know how they would fit my chassis. How much current are your amps using?
I'm relatively new to the Pass community, but FWIW - the transition from chip based amps to these was a real eye opener for me also. It's my understand that the comparatively higher temps are simply in the nature of the beast - essential to the basic design. That prompted me to experiment with liquid cooling to reduce the mass of the required heatsinks. It's still a work in progress, but one build has 12 output transistors per side instead of the two on the ACA . With the cooling system off it will boil water within minutes.
I suspect managing the heat is far superior to modding the circuits so carefully designed and graciously shared by Mr. Pass
I suspect managing the heat is far superior to modding the circuits so carefully designed and graciously shared by Mr. Pass
Exactly! It appears it's working just right.
sometimes I get concerned for people in tropical climates, but more for them cooking than the amp
sometimes I get concerned for people in tropical climates, but more for them cooking than the amp
Last edited:
Thanks I have looked at them, but what is the best way to successively built and upgrade the Zen amps--by breadboarding or PC boards?
What version of all the Zen Amps is the Amp Camp?
It is not the best looking amp built here... but sounds wondefully!
The fans are from old pc power supply and are connected to the fins by the metal cut from the same pwr supply. I added them as after the resistor mod the temp was +32°C plus ambient temp.
Now is winter and there is no problem but in summer they could easilly reach 65°C or more...
I haven't measured the current yet, I think to do it next week.
Attachments
I have built ACA # 1.
My speakers are Dynaudio Foccus 4 ohms.
In my board I added 0R47 parallel to R1 and R2, and 0R68 parallel to R3 and R4.
R12 replaced with 150K.
12.5 volt power supply with load.
I then replaced parallel 0R47 with 0R68, and parallel 0R68 with 1R.
Bias stable 6,5 v offset stable 0.0 v. Sound good.
I have now added resistor 2.7k (mod for 6 watt), bias stable 6.5v, but offset unstable betwen 2 and 6 mv. Sound so, so.
Why?
My speakers are Dynaudio Foccus 4 ohms.
In my board I added 0R47 parallel to R1 and R2, and 0R68 parallel to R3 and R4.
R12 replaced with 150K.
12.5 volt power supply with load.
I then replaced parallel 0R47 with 0R68, and parallel 0R68 with 1R.
Bias stable 6,5 v offset stable 0.0 v. Sound good.
I have now added resistor 2.7k (mod for 6 watt), bias stable 6.5v, but offset unstable betwen 2 and 6 mv. Sound so, so.
Why?
I have adjusted P1 so that the Drain pin of Q1 is set at 6.5 volts DC.
Without input signal, DC measured at speaker output is unstable (betwen 0 and 10 mv).
If I change the bias of Drain, the DC in the output increases.
Excuse my English and my poor knowledge of electronics.
Thanks