Having checked all the components as per the BOM I had a couple of things to check before I start populating the boards - For R12 & R28 I seem to have 2 x Dale resistors and 2 x generic ones (all 47K), rather than 4 x Dale. Does it matter which ones go where? Also, I seem to have 9 x 2SK209 and no 2SK170 so I assume the T092 ones are an alternative to the surface mount? Thanks....
I'm reasonably certain the "generic" 47k's are high quality industrial metal films sourced from one of the top suppliers like Mouser or Digikey. In other words, flip a coin and put the Dales in R12 OR R28 position, and the other ones in the opposite spot and enjoy the music.
In the meantime,
I'm building the umbilical:
I'm building the umbilical:
- 3x1,6 mm2 Elecadio hookup wire, drilled
- sleeve
- shielding braid
- cotton sleeve
- Viborg 4-pole XLR plug
Likely a short within the female XLR plug pins. On close inspection there were a couple of errant wires from within the braided wire. No clear contact to an adjacent pin that i could see, but cleaning that up and adding a bit of electrical tape between pins solved the problem.
The earlier failed test that generated a little smoke didnt occur with full power as i was powering up with a variac. Perhaps a quick shut down with only partial power saved the PSU board components???
All good now. Waiting for 680 Ohm resistors to make final adjustment on R27.
Still, sounding very good in my room with a Denon 103R loaded at 100 Ohms.
So, the P3 has spent a few days playing music. Seemed to me some break in — for the better — occurred (to my ears at least).
Today i reeled in the R27 values inside spec (about 4.5 mA) and added blue LEDs,…because they make the sound look better.
Also did a quick A/B with the other phono pre in the earlier picture.
All caveats for these comparisons should be kept in mind. System was elekit tu8900 (2A3 tubes), ZM Iron Pre, P3, VPI prime scout, denon 103R, Zu DW6, and the first session from Miles’ 1st great quartet (“Miles”).
Both preamps sounded lovely. The P3 is “stock”, single ended, one PSU.
No complaints at all with either and will give the P3, consistent with other impressions posted, a nod toward strong(er?) low end, spaciousness/air/openness, and in a good way perhaps more etched detail (Eg, symbol strikes). Pretty happy and may think about speaker placement a bit more.
Anyway, that’s my ear on a sunday afternoon in June with my rig and one record.
If fancier op amps can add even more, i will be a happy camper. Only one way to find out.
That provides you the inspiration and excuse to design your own upgraded and vastly improved P3.
Thanks, chedma. I appreciate you taking the time to post your impressions, especially in comparison to a well-known production piece.
nice umbilicals! May I ask how you managed to stretch the shielding braid to get the cable through? I'm trying something similar, but I am having a hard time getting my cable through the shield.
Thanks @Wellerman !
You don't have to stretch the shielding braid. On the contrary, when you start inserting the cable, you have to stop it with your right hand (using two fingers) and push it with your left hand until it "inflates" a little, then stop it with your left hand and pull it to the right, then stop it again with your right and inflate it with your left... etc.
Cable inserted:
Braid "inflated":
Other side fixed:
Braid pulled to the right/flattened:
Again, inflated, etc.:
You don't have to stretch the shielding braid. On the contrary, when you start inserting the cable, you have to stop it with your right hand (using two fingers) and push it with your left hand until it "inflates" a little, then stop it with your left hand and pull it to the right, then stop it again with your right and inflate it with your left... etc.
Cable inserted:
Braid "inflated":
Other side fixed:
Braid pulled to the right/flattened:
Again, inflated, etc.:
well, yes.