The chassis is a Bud 17x12x3 from Digi Key. The sides have been cut off to mount the heat sinks.
The output power, when calculated using wuffwaff's AXE 1.2 spreadsheet, at 4amps bias into 8 ohms is 42 watts and into 4 ohms is 26 watts.
Moe29 you are correct this unit does run too hot. After about 1 hour I can still hold my hand on the heatsinks, after another half hour the heatsinks are too hot to touch.
The amplifiers are driving back loaded Fostex 108EZ horns rated at 24 watts. At my listening levels the volume control on my Aleph P1.7 64 step relay attenuator is set about step 25.
My next step will be to rework the unit to 2.5 amps bias, again from the spreadsheet this comes out to 21 watts into 8 ohms. This should cut the power dissipation for each channel from 148 to 92 watts.
The output power, when calculated using wuffwaff's AXE 1.2 spreadsheet, at 4amps bias into 8 ohms is 42 watts and into 4 ohms is 26 watts.
Moe29 you are correct this unit does run too hot. After about 1 hour I can still hold my hand on the heatsinks, after another half hour the heatsinks are too hot to touch.
The amplifiers are driving back loaded Fostex 108EZ horns rated at 24 watts. At my listening levels the volume control on my Aleph P1.7 64 step relay attenuator is set about step 25.
My next step will be to rework the unit to 2.5 amps bias, again from the spreadsheet this comes out to 21 watts into 8 ohms. This should cut the power dissipation for each channel from 148 to 92 watts.
Hi t3447ml,
I built an Aleph30 earlier this year that consumes 100 watts of power per channel. It has one 151x350mm heatsink per channel. After about 2 hours the heatsinks still pass the 5 second touch test. I've run the amp for as long as 6 hours on a warm summer day and the amp still passed the touch test.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70622
You may need larger heatsinks even with the reduced power.
Something to consider.
-David
I built an Aleph30 earlier this year that consumes 100 watts of power per channel. It has one 151x350mm heatsink per channel. After about 2 hours the heatsinks still pass the 5 second touch test. I've run the amp for as long as 6 hours on a warm summer day and the amp still passed the touch test.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70622
You may need larger heatsinks even with the reduced power.
Something to consider.
-David
t3447ml:
the chassis look like too. do you need to purchase the bottom plate also? one more question, since you have external heatsink. and the size of the chassis is 17x12x3, so you have the 2.5" heatsink on each side of the chassis? where did you get the heatsink? digikey again? if yes, again, what is the part number? and did you get the front plate from digikey also? thanks a lot. I guess I have asked too many questions.
the chassis look like too. do you need to purchase the bottom plate also? one more question, since you have external heatsink. and the size of the chassis is 17x12x3, so you have the 2.5" heatsink on each side of the chassis? where did you get the heatsink? digikey again? if yes, again, what is the part number? and did you get the front plate from digikey also? thanks a lot. I guess I have asked too many questions.
hc167, regarding to many questions, to the contrary please ask your questions that is why I posted this project.
The Bud chassis is mounted with the large open end up. The top plate is a piece of perforated metal I was fortunate enough to find at a scrap yard.
The front panel is a piece of 1/8 inch annodized aluminum, also from the scrap yard.
The heatsinks are Conrad MF30-75, they are a beautiful piece of work, however I would take dw8083 suggestion and go larger.
When mounting the heatsinks, the 17" length of the chassis was cut on both ends and the heatsinks attached.
The Bud chassis is mounted with the large open end up. The top plate is a piece of perforated metal I was fortunate enough to find at a scrap yard.
The front panel is a piece of 1/8 inch annodized aluminum, also from the scrap yard.
The heatsinks are Conrad MF30-75, they are a beautiful piece of work, however I would take dw8083 suggestion and go larger.
When mounting the heatsinks, the 17" length of the chassis was cut on both ends and the heatsinks attached.
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