Building a Pearl 2

[6L6]

The store chassis would be great!

The Universal PSU board will work perfectly, if a little big.

 

[bnorrish]

The store chassis would be great!.

I used the chassis from Parmetal but the store chassis look like a better deal. A pair of the Galaxy 288s would be real nice!

 

[KevinHeem]

I'm in the process of ordering all my parts. I have questions on a couple parts.

According to both DigiKey and Mouser the LM7924CT is an obsolete part. Can I use the KA7924TU. If so should I then use the KA7824ETU as the +24 regulator.

I'm ordering all RN60D resistors but the 499R (R9, R28) are out of stock. Could I use 500R in it's place.

 

[6L6]

The KA7924TU is fine. This one has a little higher max input voltage - MC7924BTG ON Semiconductor | Mouser

RN60 resistors are fantastic. As are RN55.

One ohm difference is negligible.

 

[bnorrish]

Yes. I used 512-KA7924TU (Fairchild) with 513-NJM7824FA (NJR). Not critical to use same manufacturer.

500R would work. With 1% +/- tolerance, 499R vs 500R is a wash.

 

[KevinHeem]

I just noticed today that the regulators have heat sinks. Does anyone have a Mouser part number for them?

 

[6L6]

PM me your address and I will send you the heatsinks.

 

[KevinHeem]

The build is on!

I got all my parts in from Mouser today. (Merry Christmas to me).

I received my power supply kit from ChipAmp.com and transformer from Antek (AS0522). I assembled them and am getting a little over +-30V.

Today I assembled the power/regulation area on the P2 board. Tomorrow I'll connect it to the ChipAmp supply board and see what I get.

I ordered 2 Galaxy 388 Chassis from the diyAudio store and they have shipped.

Time for bed

 

[bnorrish]

Looking good. Smart to test the Reg section first - I wish I did. Had the polarity of the power incorrect and burned some resistors R1, R2 and R30, R32 if I remember correctly.

Pearl 2 sounds great!

 

[KevinHeem]

Looking good. Smart to test the Reg section first - I wish I did. Had the polarity of the power incorrect and burned some resistors R1, R2 and R30, R32 if I remember correctly.

Pearl 2 sounds great!

That was 6L6's idea

 

[KevinHeem]

testing power

Tested the regulation section of the board this morning.

First picture shows unregulated supply hook up.

Second picture shows regulated voltage.

Third picture just shows board and meters.

Fourth picture is unregulated voltage.

 

[JOHNNYCR100]

Hi bit of a random pearl question!!- Could I mount both pearl PCB boards on top of each other with brass standoffs (allowing for the regulator heat sink highs of course)
With out it getting to noisy?

cheers
Johnny

 

[6L6]

Johnny,

Yes, that will be no problem with noise.

Remember that the 10,000uF capacitors and regulator heatsinks are the tallest things on the PCB, followed by the 3,300uF capacitors.

 

[JOHNNYCR100]

got that thanks

Hi 6L6--Thank you once more sir, that will save some room then!, but- I wont push my luck and put it in a modu 5u case for the "ultimate F5 Integrated"-- (unless you know better?- I like the idea but to much transformer hum abounds--any one tried that??)

cheers

Johnny

 

[6L6]

Putting a Pearl in the same case as a power amp would hum.

 

[bnorrish]

Finally swapped out the Rega Bias 2 cartridge with a Denon DL-110 I had picked up awhile back. Big upgrade on my system with the Pearl 2! Like taking cotton out of my ears. Dramatic decrease in surface noise as well. Very happy camper!

 

[6L6]

No surprise. Rega cartridges ****.

 

[bnorrish]

I tried to keep an open mind with the Rega. I was suprised that there was such a big difference.

 

[Zen Mod]

if not Boeing , I'm not goeing

 

[KevinHeem]

Getting Close

My Galaxy 388 chassis came in (very nice).

The boards are populated:
I left R20, C7, C15, and C22 out.
I jumped R15

I have all the parts needed to finish: AC entry/fuse module, RCAs, umbilical cord, and TT grounding post.

I've mounted the PCBs in the main chassis.

I just need to find someone to machine the back panel.

And then wire it up.