I started this Aleph 5 amp project about 6 years ago.
I got it to the point that I had one channel running and playing in my garage and then it sat on my bench and started collecting dust.
I've changed my mind so much concerning the heatsinks I planned on using and how I was going to complete the chassis that I just never got anything done. It has just been sitting on my bench taunting me for the last 4 years.
About a month ago I finally got motivated and decided it was time to finish this project.
I performed all of the machining so far on my benchtop mill. I still have to make the faceplate. I'm undecided on how I want that to look!
I set the transformers and caps in on this picture to show how I'm planning the layout. The caps are Nichicon KG Gold tune 8200uF/50V. The transformers are new old stock from a Denon Integrated amp, I picked them up on Ebay. I will have to build an LC filter in the PS to drop the rails down to the necessary +/-35 vdc due to the 39-0-39 output of the transformer.
I hope to have this thing up and running in the next month!
I got it to the point that I had one channel running and playing in my garage and then it sat on my bench and started collecting dust.
I've changed my mind so much concerning the heatsinks I planned on using and how I was going to complete the chassis that I just never got anything done. It has just been sitting on my bench taunting me for the last 4 years.
About a month ago I finally got motivated and decided it was time to finish this project.
I performed all of the machining so far on my benchtop mill. I still have to make the faceplate. I'm undecided on how I want that to look!
I set the transformers and caps in on this picture to show how I'm planning the layout. The caps are Nichicon KG Gold tune 8200uF/50V. The transformers are new old stock from a Denon Integrated amp, I picked them up on Ebay. I will have to build an LC filter in the PS to drop the rails down to the necessary +/-35 vdc due to the 39-0-39 output of the transformer.
I hope to have this thing up and running in the next month!
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@Carpenter
No, I have not fired it up on these heatsinks yet. I was worried about the heat as well, thats why I used 3 sinks and broke up the outputs into groups of 4. That should put me at or slightly below 100W per sink. The sinks measure 15.75"W X 7"H. The fins are approx. 1.25" tall and heavily ribbed for increased surface area. The base plate of the sink is .360" at the thinnest location. I plan on doing and extended heat test on the bench this week. If they are not up to the task then I have some ideas to enhance their cooling capacity.
I'm most worried about the rear plate due to the fact I had to machine a bunch of the fins away to make room for the connections.
Here is a closeup of the sinks...
@JC
My friend at work was trying to talk me into wood. I'm actually considering it. It just seems like a waste to not make a nice metal plate due to me having a milling machine.
No, I have not fired it up on these heatsinks yet. I was worried about the heat as well, thats why I used 3 sinks and broke up the outputs into groups of 4. That should put me at or slightly below 100W per sink. The sinks measure 15.75"W X 7"H. The fins are approx. 1.25" tall and heavily ribbed for increased surface area. The base plate of the sink is .360" at the thinnest location. I plan on doing and extended heat test on the bench this week. If they are not up to the task then I have some ideas to enhance their cooling capacity.
I'm most worried about the rear plate due to the fact I had to machine a bunch of the fins away to make room for the connections.
Here is a closeup of the sinks...
@JC
My friend at work was trying to talk me into wood. I'm actually considering it. It just seems like a waste to not make a nice metal plate due to me having a milling machine.
Attachments
I have a chassis with heatsinks that are two inches deep. The chassis is about the same size as yours. The ribs are 1/4" wide with 1/4" spacing.
Every Zen amp pair, including a 12 volt Aleph-X pair, that resided in that chassis could take it to 50 degrees C +.
If yours is a monoblock, you're probably in good shape. I'd try that before attempting a stereo pair in the same chassis. Nelson says something to the effect: "When it comes to class A, you can never have too much heatsink."
Every Zen amp pair, including a 12 volt Aleph-X pair, that resided in that chassis could take it to 50 degrees C +.
If yours is a monoblock, you're probably in good shape. I'd try that before attempting a stereo pair in the same chassis. Nelson says something to the effect: "When it comes to class A, you can never have too much heatsink."
The inductors I am using are a 1mh 14 guage air core that I had left over from a speaker project from many years ago. On the capacitors, I have 16 of the 8200uf/50v Nichicon KG caps so 131,200 uF total... I also have some 47Kuf/50V computer grade electrolytics that I may add into the mix if I think I need them.
Well its looking pretty good so far.
I have had it running for about 4 hrs on the bench. The Right/left side sinks are running at about +31C over ambient temp after 4 hrs. The rear sink is running about +35C over ambient temp. This is with the bias at about 3.7A per side if I'm calculating it properly that is. I'm seeing .610V-.630V across the 1 ohm source resistors. I'm guessing that part of the reason for this is my higher than original rail voltages of 35.5 volts. This should come down once the inductors go in. I also still have the original values in for R19-R21 and have not played with the bias/AC gain settings yet.
DC offset looks good at 20mv/30mv. I originally had 300mv+ on both sides. Then I went back and looked at the boards I have and realized that I put one of my matched 9610'S into the Q3 location. On the PCB's I have Q1/Q3 are next to each other so its easy to put your matched pair in the wrong location if you don't pay attention. Once I swapped those around the DC offset came right down.
So far it sounds very good, of course its in the garage!
I'm running it with my Hafler DH-110 pre-amp and using my little Klipsch KG .5 speakers for now.
It is very quiet with approx 75K uf of capacitance per rail there is very little audible hum. I have not installed the inductors yet so I expect it to get a bit quieter after that. Ther is no turn on/off thump that I have been able to discern either. Overall I'm very happy with the results so far...
I have had it running for about 4 hrs on the bench. The Right/left side sinks are running at about +31C over ambient temp after 4 hrs. The rear sink is running about +35C over ambient temp. This is with the bias at about 3.7A per side if I'm calculating it properly that is. I'm seeing .610V-.630V across the 1 ohm source resistors. I'm guessing that part of the reason for this is my higher than original rail voltages of 35.5 volts. This should come down once the inductors go in. I also still have the original values in for R19-R21 and have not played with the bias/AC gain settings yet.
DC offset looks good at 20mv/30mv. I originally had 300mv+ on both sides. Then I went back and looked at the boards I have and realized that I put one of my matched 9610'S into the Q3 location. On the PCB's I have Q1/Q3 are next to each other so its easy to put your matched pair in the wrong location if you don't pay attention. Once I swapped those around the DC offset came right down.
So far it sounds very good, of course its in the garage!
I'm running it with my Hafler DH-110 pre-amp and using my little Klipsch KG .5 speakers for now.
It is very quiet with approx 75K uf of capacitance per rail there is very little audible hum. I have not installed the inductors yet so I expect it to get a bit quieter after that. Ther is no turn on/off thump that I have been able to discern either. Overall I'm very happy with the results so far...
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