This was circuit that oscillated when the bias go into class-AB.
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Attachments
Work in progress
Working on the chassis for Wiederhold77 Quasi Hexfet.
Solid Aluminum chassis (1 inch thick, approx 1.8kg), heatsink (0.7kg),
copper spreaders isolated from the chassis - each of them will handle
1 pair of Fets.
Lots of drilling, tapping, milling, sanding and polishing 🙂
For isolation of the spreaders from the heatsink, this thermal pad has been used:
https://www.amazon.com/gp/product/B075JCQPD2/
Working on the chassis for Wiederhold77 Quasi Hexfet.
Solid Aluminum chassis (1 inch thick, approx 1.8kg), heatsink (0.7kg),
copper spreaders isolated from the chassis - each of them will handle
1 pair of Fets.
Lots of drilling, tapping, milling, sanding and polishing 🙂
For isolation of the spreaders from the heatsink, this thermal pad has been used:
https://www.amazon.com/gp/product/B075JCQPD2/
Attachments
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Solid Aluminum chassis (1 inch thick, approx 1.8kg), heatsink (0.7kg)
- Why do you need such a small radiator? Place transistors on the stove.
- Why do you need such a small radiator? Place transistors on the stove.
Ready for wiring
Ready for wiring. I guess tomorrow is another day..
All TO-126 transistors did not line up perfectly on the same level..
Each hole is up/down by 1-2mm
Apparently MJEs and 2SC/2SA and BD139 are not exactly the same...
Hope this small heatsink will be enough for drivers..
Now time for turkey 🙂
Ready for wiring. I guess tomorrow is another day..
All TO-126 transistors did not line up perfectly on the same level..
Each hole is up/down by 1-2mm
Apparently MJEs and 2SC/2SA and BD139 are not exactly the same...
Hope this small heatsink will be enough for drivers..
Now time for turkey 🙂
Attachments
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use google search for this text:
"nested oos" site:www.diyaudio.com
or whatever other term you looking for
Copy the whole line from above into google, and search
Well, not much comes up 🙂
"nested oos" site:www.diyaudio.com
or whatever other term you looking for
Copy the whole line from above into google, and search
Well, not much comes up 🙂
Wiederhold77 HexFet Quasi
Amp is done. Plays music, sounds great. Very deep bass.
Heatsinking is I guess little bit over the top, the whole thing doesn't even get warm at high power levels.
Small heatsink for TO126s id also fine. Running at 30-40 C.
Sounds just like LMK amp previously built, but I guess with slightly deeper bass (subjective opinion).
One thing - this amp doesn't like my DAC (Schiit Modi 3) - there was hum in the speakers.
I have 2 (or 3) different DACs and some of my amps don't like some of them.
Also depending if I feed the DAC from USB or via SPDIF - it affects ground hum in some amps.
So for this test I had to use another DAC, and it worked perfectly....
I tried many times to track this problem down, but it is what it is: some amps work fine with DAC #1,
other amps with DAC #2..
Without input plugged in, the amp is dead silent, regardless of which DAC is used.
Amp is done. Plays music, sounds great. Very deep bass.
Heatsinking is I guess little bit over the top, the whole thing doesn't even get warm at high power levels.
Small heatsink for TO126s id also fine. Running at 30-40 C.
Sounds just like LMK amp previously built, but I guess with slightly deeper bass (subjective opinion).
One thing - this amp doesn't like my DAC (Schiit Modi 3) - there was hum in the speakers.
I have 2 (or 3) different DACs and some of my amps don't like some of them.
Also depending if I feed the DAC from USB or via SPDIF - it affects ground hum in some amps.
So for this test I had to use another DAC, and it worked perfectly....
I tried many times to track this problem down, but it is what it is: some amps work fine with DAC #1,
other amps with DAC #2..
Without input plugged in, the amp is dead silent, regardless of which DAC is used.
Attachments
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With this loop gain and linearity of the path, the amplifier must sound .Distortions would be good to measure
Maybe you need an input buffer or preamp.
Maybe you need an input buffer or preamp.
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With the same PSU, same speakers, and same input, this amp feels
more powerful than previously built LMK and Wiederhold LatFet.
"Stronger" sound, louder, more bass, even though it's a quasi, built with cheap vertical fets.
Overall I like it better. Really good amp! 😀😀😀
With another DAC used as a source, amp is dead silent, no hum of any kind.
So I guess one conclusion is clear - expensive LatFets do not guarantee good (subjective) sound.
Next step - measurements with audio analyzer.
Perhaps we will discover that quasi sounds better (to me), because it has higher Thd ?? 🙂
more powerful than previously built LMK and Wiederhold LatFet.
"Stronger" sound, louder, more bass, even though it's a quasi, built with cheap vertical fets.
Overall I like it better. Really good amp! 😀😀😀
With another DAC used as a source, amp is dead silent, no hum of any kind.
So I guess one conclusion is clear - expensive LatFets do not guarantee good (subjective) sound.
Next step - measurements with audio analyzer.
Perhaps we will discover that quasi sounds better (to me), because it has higher Thd ?? 🙂
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Add (L) -R-C filter at the DAC output with background. Possible frequency component above the audio range.
№326. Collector Q10 can be powered from -15V
№326. Collector Q10 can be powered from -15V
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