That is an obsolete part now. Some replacements were listed 2 pages back.
For some reason, I can get total BOM price. It is about 65 GPB + VAT. Add PCBs and some misc. parts ant total cost is about 100 GPB.
I purchased the SQP120N10-09_GE3 at Digikey (today 229 in stock). The -3M8_GE3 is obsolete (as @tombo56 mentions above, too). From the data of both FETs I consider the -9_GE3 almost equivalent to the 3M8 except that the input capacity is with 8645pF higher than the 7230pF (GE3). Maximum power, however, is 375W instead of 250W.
Edit: Just saw that @tombo56 suggested 09_GE3 officially (see page 7).
Last edited:
Hi Tombo,
I build 4 boards base on your positive.sch, but only one board works correctly. The output voltage of other 3 pieces always equal the input when I turning the potentiometer. The green led alway truns on, the red led turns off or on or flash when I turning the potentiometer.
Any ideas where I have to look for my errors?
A list of replacement parts is attached
I build 4 boards base on your positive.sch, but only one board works correctly. The output voltage of other 3 pieces always equal the input when I turning the potentiometer. The green led alway truns on, the red led turns off or on or flash when I turning the potentiometer.
Any ideas where I have to look for my errors?
A list of replacement parts is attached
- ZTX958 and BC327-25 ware replaced with BC556B transistors
- Q5 - SUP60061EL-GE
- R7 - 4K7
- C5 - 47pF
WTF - Design by MX studio – All rights reserved.
Really?
What rights?
This design was meant for diyaudio only, not to be sold by third party.
Time to bring this thread back to the right track, my experience with the R21 modules.
To start with, the setup:
Six fully separate power supplies, where 300VA transformers charge capacitors with 0.1F each via 0R1 resistors. The diodes have snubbers. The DC of +- 30V feed six P3A amplifiers (Rod Elliott) in its original versions except for the high frequency branch, where the VAS stage got a five-transistor current mirror and emitter degeneration for the differential pair. The drivers were selected for high efficiency, low mechanical loss, and low distortion (coming from 18Sound: 15" in a closed box, Accuton 173Nd and a large Mundorf AMT). The digital data from a PC go via a Dante network into a HD2, which provides FIR filtering with a linear phase down to 20Hz.
Up to now, the sound of this setup was pleasant to listen to, but at larger volumes many recordings, especially from the progressive rock genre, produce fatigue after a while. Vocals (e.g., the marvelous Dorothea Mields, whom we heard live in concert) had some kind of unnatural sharpness, therefore, room for improvements,
For fitting the four modules into the casing, one of the transformers and its capacitor bank had to leave and where replaced by four R21 modules. The output voltages were set to 26V (30V is the input from the remaining capacitor bank). For getting an AB comparison, one channel was changed and could be compared to the unmodified one:
The unmodified channel had a noticeable brightness in the mids and highs relative to the R21-channel. My wife confirmed this impression without knowing, what I have changed. Furthermore, the sound stage seemed to be a bit more flat with less separation into the stage. So a good incentive to modify the other channel as well.
Wow! The brightness at louder volumes has reduced significantly. Three, four dB louder than before, no problem! Since my wife and me are quite sensitive to distortion, this mod was not the cheapest one (this was removing the screen of the XLR cables from pin 1), but definitely worth it!
Fazit: A simple amplifier such as the P3A (which suffers obviously from a low PSRR) benefits a lot from a ripple-free DC, so go for it.
@tombo56: My sincere thanks for elaborating these modules and providing the Gerber files! I really appreciate this
To start with, the setup:
Six fully separate power supplies, where 300VA transformers charge capacitors with 0.1F each via 0R1 resistors. The diodes have snubbers. The DC of +- 30V feed six P3A amplifiers (Rod Elliott) in its original versions except for the high frequency branch, where the VAS stage got a five-transistor current mirror and emitter degeneration for the differential pair. The drivers were selected for high efficiency, low mechanical loss, and low distortion (coming from 18Sound: 15" in a closed box, Accuton 173Nd and a large Mundorf AMT). The digital data from a PC go via a Dante network into a HD2, which provides FIR filtering with a linear phase down to 20Hz.
Up to now, the sound of this setup was pleasant to listen to, but at larger volumes many recordings, especially from the progressive rock genre, produce fatigue after a while. Vocals (e.g., the marvelous Dorothea Mields, whom we heard live in concert) had some kind of unnatural sharpness, therefore, room for improvements,
For fitting the four modules into the casing, one of the transformers and its capacitor bank had to leave and where replaced by four R21 modules. The output voltages were set to 26V (30V is the input from the remaining capacitor bank). For getting an AB comparison, one channel was changed and could be compared to the unmodified one:
The unmodified channel had a noticeable brightness in the mids and highs relative to the R21-channel. My wife confirmed this impression without knowing, what I have changed. Furthermore, the sound stage seemed to be a bit more flat with less separation into the stage. So a good incentive to modify the other channel as well.
Wow! The brightness at louder volumes has reduced significantly. Three, four dB louder than before, no problem! Since my wife and me are quite sensitive to distortion, this mod was not the cheapest one (this was removing the screen of the XLR cables from pin 1), but definitely worth it!
Fazit: A simple amplifier such as the P3A (which suffers obviously from a low PSRR) benefits a lot from a ripple-free DC, so go for it.
@tombo56: My sincere thanks for elaborating these modules and providing the Gerber files! I really appreciate this
Last edited:
I admit that I haven't really caught on to the LED's function. Green seems to indicate that the voltage is "in range" for input and that we're regulating. Red seems to indicate that the voltage is out of range (on the input) and no bueno. I have yet to see the red flash. I bumped up the input voltage to ~20V and set the output to 17V5 and varied the input voltage.
I got all of them adjusted with no load, and then one with a small load (couple of 220R 3W for ~0A2) just to check that I hadn't majorly goofed anything. I had to take a break for non-DIY activities before I finished doing all the proper checks with a load and getting them set. - DRAT!
More to come. Tips / Tricks / Noticing Screwups is always appreciated.
I got all of them adjusted with no load, and then one with a small load (couple of 220R 3W for ~0A2) just to check that I hadn't majorly goofed anything. I had to take a break for non-DIY activities before I finished doing all the proper checks with a load and getting them set. - DRAT!
More to come. Tips / Tricks / Noticing Screwups is always appreciated.