Thanks Patrick. I thought about using the Toshiba parts because I have them. However, I did secure a small stash of the 2SK209GR devices due to you highlighting them.
I will try and play with the sim.
Mogens
Do the upper and lower mosfets need to be matched together?
Or matching is needed only for the upper and lower pairs? Meaning 2 pairs and not a matched quartet?
Question on the OPA 604 opamp: it is still active, but not a single supplier has any stock, so it has basically become unobtainium. I checked the TI website, and they have many other audio opamps, but almost all of them can only have +/- 18 V supply. Would it be OK to feed them from a secondary supply with a L7818 3-point stabilizer connected to the 24 V rail? Would involve making a seperate PCB for the servo..
I bought this one recently https://www.ebay.com/itm/252046879741
From China, it works at 22.5 volts in my case.
Rush
From China, it works at 22.5 volts in my case.
Rush
Thanks Patrick! I will order them from Mouser, together with the other components. Just ordered the pcb's from JLCPCB with your gerber and will assemble it in a week or so.
And I might even give a shot at the 50 W 8 Ohm version, after I got some experience with the V2 first. Your spice model of that gives promising results.
Good amp for very little money.
No unobtaniums.
And all FET.
🙂
Patrick
No unobtaniums.
And all FET.
🙂
Patrick
For the 32 V 8 Ohm version, I may try the OPA445. But not sure if I will insert the servo into that pcb design or not, have some more studying to do..
There is no need to install servo by default.
You should build basic amp first, and loaded it with a dummy load.
Then you see how much drift you have on your case / heatsink.
If the drift is say < +/-100mV, I would not bother with servo.
More useful to install a speaker protection circuit.
For example that from Pavel :
https://www.diyaudio.com/community/threads/output-relays.191449/post-2835407
Patrick
You should build basic amp first, and loaded it with a dummy load.
Then you see how much drift you have on your case / heatsink.
If the drift is say < +/-100mV, I would not bother with servo.
More useful to install a speaker protection circuit.
For example that from Pavel :
https://www.diyaudio.com/community/threads/output-relays.191449/post-2835407
Patrick
Thanks Patrick!
Will do so. )n my F5T I used the speaker protection from the DiYAudioStore. Works nice also.
Will do so. )n my F5T I used the speaker protection from the DiYAudioStore. Works nice also.
just ordered all parts from Farnell (they deliver much faster in NL), including some heatsinks, and will first breadboard the amps using a lab power supply. Will compare the UDNeSS V2 and the 32V/8Ohm. To be continued in a few weeks..
There should be some large power rail caps close to the amp PCB.
Say 10,000µ, even with lab supply.
Patrick
Say 10,000µ, even with lab supply.
Patrick
Still have a pile of those lying around, from my F5T PSU build, so I can line up 40.000 uF per rail. Thanks for the tip!
post 351 "There is no need to install servo by default.
You should build basic amp first, and loaded it with a dummy load.
Then you see how much drift you have on your case / heatsink."
There is no need for an output coupling cap, in our experience.
The 10,000µF above (post #354) is meant for power supply rails.
Patrick
The 10,000µF above (post #354) is meant for power supply rails.
Patrick
That is what I understood: 10.000 uF over the rail voltages. I guess the audio frequency AC current in the rails (amps) needs a charge buffer that lab supplies don't have.