So I don't really want to have a separate power supply cabinet. Is it possible to put the power supply in the same cabinet as the pearl circuit without causing any problems?
Yes, it is however possible. But be prepared to be more exposed to hum problems, because your circuit will likely get more parasitic magnetical flux losses from the transformer. You can cure this by moving / orienting the transformer in a way noise is minimized. Is distance is good enough, your circuit wil have more chances to produce quiet operation.
Best,
nAr
Questions for Tea-Bag's post #599
Hi Tea-Bag,
Thanks for posting your shunt regulator picture. With off-board voltage regulation, what parts on the Pearl II PCB did you omit? Also, where on the Pearl II PCB did you connect input voltages? Thanks for the information.
Gary
Hi Tea-Bag,
Thanks for posting your shunt regulator picture. With off-board voltage regulation, what parts on the Pearl II PCB did you omit? Also, where on the Pearl II PCB did you connect input voltages? Thanks for the information.
Gary
Gary,
This is what it looks like, and how to add in V+ and V-
There are several ground points to choose from.🙂
If I can get this running, bout anyone can!
NOTE FOR OTHERS: The Regulator has been removed, for replacement of an off board one. This is NOT the default PEARL 2 schematic.
Attachments
Last edited:
it's always possible. And done all the time. As nAr said, it's just a little riskier. making a separate compartment with some shielding can help. Also, the field strength follows inverse square law (dropping off proportional to distance squared), so any extra distance you can provide inside the chassis goes a long way. If you have a big chassis this is good 😉
If you take a bit of care in dressing/twisting wires, and chassis layout, you should not have any problems.
That said, for my current phono, and for the Pearl2 (when I get to it) I put the transformer and fuse in a small external enclosure, and just ran the low voltage AC to the preamp.
-Chris
This is always a preferred solution, even if it raises cost and complexity for supplementary I/Os. At least the phono stage can be in a closed aluminum box that is directly linked to Earth, audio ground is separated from chassis. The PSU box can be conveniently put 2 meters away the turntable and Pearl II. I push the ridiculous side to put the rectifiers and 1st pair of reservoirs near the transformer, in the PSU box, to carry only unregulated DC to the Pearl II box. As the PSU ground is also a signal ground, at this place I link audio ground to Earth via a thermistor CL60. For now it doesn't fail, ground connection but no loop. And no noise, it is totally silent ! 🙂 Except for Music 😉
Today I made some internal subjective wiring tests.
For the inputs I now use 30 AWG copper silver-plated, with Kynar insulation, unshielded. It seems to suit the cartridge prolongation very nicely 🙂 No noise, it is still dead silent.
For the output section, what gives best subjective result is a twist of 2 x 30 AWG Kynar insulated wires. I recall the difference between gauges :
20 AWG 0,812 mm dia. / cross section 0,5190 mm2 (standard hookup wire)
30 AWG 0,255 mm dia. / cross section 0,0503 mm2
So output section is only 0,1006 mm2.
Multistranded wire of thicker dia. proved to gave poorer results, revealing a simplified / muddied / rounded sonic result.
Best upgrade would be to use the silver ribbons. I will make them later as part of an upgrade kit 🙂 So, it leaves room for progression, still 🙂
Best regards,
nAr
Completed my two Pearl 2 PCB. They worked perfectly the first time 😉
I checked the RIAA curve accuracy, and it is almost perfect, textbook results. Great work Wayne!
And I took DC voltage measurements all around the circuit. These readings are great when you service a board. It may be usefull for some of you guys 😀
I checked the RIAA curve accuracy, and it is almost perfect, textbook results. Great work Wayne!
And I took DC voltage measurements all around the circuit. These readings are great when you service a board. It may be usefull for some of you guys 😀
Attachments
Great to hear that so many have completed P2 and it seems good. I did the XONO about 6 months ago, so, still listening to that. Haven't even order the parts to go on the P2 boards yet...so, I'll be reading up and asking for parts list etc...soon!
So, any finished pictures, etc?
T
So, any finished pictures, etc?
T
Mine is still working nicely and almost finished, except PSU box (grrr I hate to say it) and service led not mounted on faceplate
Actual PSU
I think the 300VA Rcore is more than enough 😀
a Back View
From right to left : inputs, outputs, (white) ground point for turntable, and just behind is hidden the power con ( 4 pin mike robust plug with lock, carrying V+, GND, V-, Earth )
Pearl II
Enclosure is HiFi2000 Galaxy GX383 10mm silver faceplate, all aluminum, perfect dims for Pearl II boards 😎 those chassis really are about the best value money can buy
Best,
nAr
I'll try to measure them and report here when I get home, by the evening here ( GMT+1 ) 🙂
Best,
nAr
Hey guys,
I ordered the 0.1 uF caps with 10mm lead spacing instead of 5mm. If anyone here has about 22 extra, I could use them. I just want to put this here before I ask in Swap Meet.
I can pay or trade with the 10mm ones.
I ordered the 0.1 uF caps with 10mm lead spacing instead of 5mm. If anyone here has about 22 extra, I could use them. I just want to put this here before I ask in Swap Meet.
I can pay or trade with the 10mm ones.
Sorry, now the pre is boxed and I can't measure @ that point for now, but I think about 9V is a correct value, I think I measured it and you're about fine, this reading is different than in the AlephOno where voltage seems to be a little higher.
Sorry not to have measured again 😎
I ended using a signal white led 3 mm plugged on the unregulated 36V or so, with a 100k series resistor, yes you read right, 100k series, and it is still bright 🙂
At night
Best,
nAr
Last edited:
FWIW
Just picked up a pair of R or D core trannies at .8 amp 115v 2X 24+24vac and the dang things measure 28+28vac at exactly 115v or 40.80 vdc at the caps unloaded
The label is in english for crying out loud!
Looks like a rewind is in my future alas...
Just picked up a pair of R or D core trannies at .8 amp 115v 2X 24+24vac and the dang things measure 28+28vac at exactly 115v or 40.80 vdc at the caps unloaded
The label is in english for crying out loud!
Looks like a rewind is in my future alas...
Slyvain
Before I do anything,send me a PM on your thoughts of your Xono vs the Pearl 2 and what you think sounds better. The raw 40v would work OK there, but would mean buying all new pts. for it.
I might need the gain for my Winlabs Jewel MC and a MC10 carts.(not FET)
Regards
David
Before I do anything,send me a PM on your thoughts of your Xono vs the Pearl 2 and what you think sounds better. The raw 40v would work OK there, but would mean buying all new pts. for it.
I might need the gain for my Winlabs Jewel MC and a MC10 carts.(not FET)
Regards
David
FWIW, i'd think twice about how these things are wound first, then forget about it.
Couple of years ago i rewound two 500VA R-cores for Bruno Putzeys ExtremA power amp design : Sheer Hell.
Rewinding smaller D/R-core transformers is less work, but just as difficult, not worth it in my book.