My Pearl Phono Section

[Algar_emi]

Following Promitheus Pearl Group Buy, see http://www.diyaudio.com/forums/showthread.php?s=&threadid=52278&pagenumber=1
I started my Pearl phono stage. It will have a separate power supply using a Plitron transformer. Here the complete Power supply:

 

[Algar_emi]

Here the inside of the Power Supply, really compact.

 

[Algar_emi]

I'm using an EMI filter and a AC inlet with built-in fuse socket. The power supplies grounds will be connected inside the preamp directly at the ground lug. The power cable is also shielded using two complete separate pairs, one per supply. A screw terminal is used to connect all of the transformer wires, the AC input lines and the EMI filter.

 

[Algar_emi]

I modified one of the PCB to supply a front panel Power-On red light. I'm using a small header 2 pins connector for the led.

 

[jonclancy]

Nice work there!! Very tidy indeed!!

Jon

 

[Manu]

Beau travail. Bravo!
Manuel

 

[Stevox]

Looks very very good... nice solution for the power led.
By the way, what value are you using for the resitor for the led.

peter.

 

[Algar_emi]

Thanks for your nice comments. The led resistor is 10K. I also added a resistor of 33K, 1/2W under the big 10000uF cap to drain the supply after power down. I already burn my nice side-cutter blade because I discharged by accident the big cap with it...

To install the led header and resistor, I made sure that one pin of the header was solder to the V+ trace and that one led of the resistor was connected to the GND pcb trace. Then the other resistor leg hold the header other pin. It is working well. The PCB seems to be original...See the image for details.

For the one that want to know the enclusure is from Hammond. It is tough, rather nice looking, easy to work with and shield the transformer stray field because it is made of steel. You can get it easily from Digikey, Part No: HM336-ND.

 

[Algar_emi]

Here the led, burning bright

 

[Algar_emi]

I completed the assembly of both PCB, normal Pearl and MC Option. The kit supplied by Prometheus was perfect, no part was missing or incorrect. Here the maain Pearl PCB (MM section)

 

[Algar_emi]

Parts quality were also very high. Here the MC section (option)

 

[vinylkid58]

Nice work with the power supply. May I ask where the case came from?

Jeff

 

[Algar_emi]

It is in the post, but I don't mind to repeat it

"For the one that want to know the enclusure is from Hammond. It is tough, rather nice looking, easy to work with and shield the transformer stray field because it is made of steel. You can get it easily from Digikey, Part No: HM336-ND"

Bye...

 

[Pathmark]

Hi Algar,

Can you let me know part # or name of emi filter? Also do you have some recommendation for connectors used to connect to phono chassis?

Pathmark

 

[Algar_emi]

I got the EMI filter from a surplus store. It is a DELTA, part number 03DBAW5. I'm using Cardas RCA panel mount connector.

 

[Algar_emi]

I'm almost done with the Pearl casing, more on that later. For now, here my PCB under testing. They are working perfectly, as per the original Pearl schematic voltage values.

 

[Algar_emi]

Both PCB's will be mounted in there separate enclosure, fully shielded. The power will come from between each channel. The common gnd point and gnd lug will also be located there. To ease the pcb installation and servicing, I installed some nice gold plated pins from AMP. here a look.

 

[Stevox]

Hi Algar,

Looks very nice...

I'm curious how you managed the grounding, and if you connected it to chassis.

Peter.

 

[Algar_emi]

I built an ONO preamp for my main system prior to this one. In the ONO, the separate dual mono supplies are connected together inside the power supply, then to the chassis through a CL-60. Then the ONO chassis is is connected to the supply chassis using the power cable shield. The GND lug on the ONO is connected to the chassis. So, the power gnd is floating and is referenced to the AC outlet power ground only through the CL-60 normally high-impedance. But all the chassis are grounded.

I can send you a schematic of the complet interconnect if you want.

For the Pearl, I would like to try something different. The external supply has the two independant rectifier/cap PCB, then the two +45V ar sent separately to each Pearl preamp PCBs (the supply casing is grounded to the power gnd). Then, I will connect each PCB star gnd point (marked "Connect Ground Here" in the middle of the PCB) to the insulated GND lug. I will also connect the preamp enclosures to this gnd. So the GND lug will be the connection point for all the GND. I'll see what is the result.

 

[Stevox]

Hi Algar,

I'm very interesting in your schematic, If you want you can mail it to me.

I think that the ground connection you would do for the pearl, is the same as I did.

first the gnd lug was insulated from chassis, but after a while I connected both, because there was a little hum.


thanks.
Peter.