setup and feeling on my very good Hifi chain and KEF R11;
Rail 23,25V and 1,55A (limit 36W/ch); 4U/400; OPA604AP; local Feedback
These are my personally feelings and not more!
compared to my F5 (also Fairchilds):
cons:
womens voices could be a little bit warmer, slightly more
slightly more texture in the very high end freq.
a lack of lower end "meat", -not punch and pressure
pros:
M2OPs is faster without any fog, any
very thrilling and a touch more decay==> so it is touch more air all around the actors
F5 is playing in a large triangle -M2OPs sounds in a bit smaller but very deep trapezoid
stage and positioning is very clear and no mixing in positioning of actors in sound
feels like: F5 is more Class A "layback"- M2OPS is more like Class AB-"lets do this"
very good punch and pressure
Thanks Patrick for this project.
next: OP-amp rolling; got OPA627BP!! OPA551 and AD828
Rail 23,25V and 1,55A (limit 36W/ch); 4U/400; OPA604AP; local Feedback
These are my personally feelings and not more!
compared to my F5 (also Fairchilds):
cons:
womens voices could be a little bit warmer, slightly more
slightly more texture in the very high end freq.
a lack of lower end "meat", -not punch and pressure
pros:
M2OPs is faster without any fog, any
very thrilling and a touch more decay==> so it is touch more air all around the actors
F5 is playing in a large triangle -M2OPs sounds in a bit smaller but very deep trapezoid
stage and positioning is very clear and no mixing in positioning of actors in sound
feels like: F5 is more Class A "layback"- M2OPS is more like Class AB-"lets do this"
very good punch and pressure
Thanks Patrick for this project.
next: OP-amp rolling
; got OPA627BP!! OPA551 and AD828
Last edited:
You should try mixed feedback first.
Will give you much more control, tighter bass.
Toshiba also slightly more than Fairchild.
627 and 828 are not specified for+/-24V.
604 is probably a better choice than 551.
But have a comparison by all means.
If you want the absolutely best device, I would say 2SK1530/2SJ201.
But my taste only.
Patrick
Will give you much more control, tighter bass.
Toshiba also slightly more than Fairchild.
627 and 828 are not specified for+/-24V.
604 is probably a better choice than 551.
But have a comparison by all means.
If you want the absolutely best device, I would say 2SK1530/2SJ201.
But my taste only.
Patrick
Last edited:
Thanks @Vunce , what's the little fan and the control board? Looks like you also used their extra capacitor boards..Did you go CRC? (I can't see the 'R', value?)Thanks
The power supply is a Micro-Audio SMPS500-CLA.
When was the decision made to put a pair of physically large lytic caps on the OPS boards? IME this is a great way to inject radiated noise from the mains transformer. Why are they needed?
That SMPSU has a secondary 12V output - could power the front end OpAmp
.. And what are the small blue/red wires for, showing at the corners of the cap boards?
Thanks all
Last edited:
Hi. I was looking to try different amounts of mixed feedback and would appreciate some guidance on how the resistor values are chosen/calculated. In the example of applying 20db global to local, the values were 47K and 470K. Is there some in-between calculation steps that might help me understand how those amounts were arrived at?
- Noctua NF-A4X10 PWM fan
- PWM control board with temp sensor to adjust fan speed
- RCC (0R22, 10000uF, 10000uF) configuration for each cap board
- Small gauge red/blue wire harnesses are power for future speaker DC protection boards
The M2OPS is definitely worth building von Ah. If you are planning to use the same SMPS keep the bias current close to 1.3A, the fan is more an option instead of strongly recommended. I'm liking the mixed feedback setup with Toshiba mosfets. Very engaging, hard to turn the system off even when its past my bedtime 
.
.
I agree, highly engaging. Mine has not left my system since being completed and the only reason I am driven to build more amps is that I have this incurable disorder that is highly contagious and has inflicted more delight on Greedy Boyz than any other illness known to date.
to clarify:setup and feeling on my very good Hifi chain and KEF R11;
Rail 23,25V and 1,55A (limit 36W/ch); 4U/400; OPA604AP; local Feedback
These are my personally feelings and not more!
compared to my F5 (also Fairchilds):
cons:
womens voices could be a little bit warmer, slightly more
slightly more texture in the very high end freq.
a lack of lower end "meat", -not punch and pressure
pros:
M2OPs is faster without any fog, any
very thrilling and a touch more decay==> so it is touch more air all around the actors
F5 is playing in a large triangle -M2OPs sounds in a bit smaller but very deep trapezoid
stage and positioning is very clear and no mixing in positioning of actors in sound
feels like: F5 is more Class A "layback"- M2OPS is more like Class AB-"lets do this"
very good punch and pressure
Thanks Patrick for this project.
next: OP-amp rolling
this was an impression after 15 hours burn in, it could be doing better after 50 h running............report will we follow up
You will need a 4 wire fan for this https://a.aliexpress.com/_Ex2XVft
There are other models that support 2-3 wire fans like this one https://a.aliexpress.com/_EwTG54x
Thank you Patrick. If I wanted to reduce the negative feedback would it be better to adjust frontend gain resistor (470K) lower or Closed loop gain resistor (47K) higher, or a bit of both?