Building a Pearl 2

[McQuaide]

I don't want to make this thread about image hosting, I'm happy with what I'm doing having learned a lesson from Dropbox.

What does the board think about removing the caps on the Pearl 2's output? A buddy of mine says that given the BA-3 has no cap on the input, this is a no-no.

 

[6L6]

Why do you want to do that??

 

[McQuaide]

Because someone is this thread said Wayne said it can be done if the DC offset is zero due to the extra cap being added to R14. I'll have to find the post.

 

[codyt]

I asked Wayne about it. He thought it was a fine idea. In fact, didn’t the same change occur in the new 2018 line stage boards?

 

[codyt]

Use a nice electrolytic 25 volts or more and a bypass. Silmic or something similar or for he supply. Bob Cordell had some good advice on this at 2016 BA talk. If you get it all setup and adjusted you may not need output cap.

I think this gave me the initial inspiration

 

[6L6]

The added caps on the BA2018 are power supply decoupling. The R14 cap on the pearl 2 is DC blocking set in the return flow instead of the signal flow.

 

[codyt]

Ah, gotcha

 

[exojam]

Well after having the boards for years now, I was finally able to get everything together. I ended up with two housings, one for power and the other for the boards.

In the power supply box I have the power supply for the Pearl 2 boards, a power supply for the B1 and one for the TT motor drive board.

In the board chassis I have the Pearl 2 boards, the B1 and the TT Drive Controller board.
Plus some very big a$$ caps.

I have already set the test point to zero volts.

Now I will begin on the reassemble of the actual TT.

I just wish I would have done this years ago when I first purchased the Pearl boards but that is life.

Sorry the pics are upside down.

 

[codyt]

Looks great! I like the idea of incorporating b1

 

[exojam]

Thank you.

I have a few friends that have done this and love it.

I had the B1 up and running for years and than purchased the Pearls when they first hit the streets but just never got to them.

I am really glad I picked up that chassis from 6L6 many years ago since it fits everything in it.

 

[exojam]

I am also very excited to get the system together so I can run the new TT motor and the associated controller board so I never have to sit there with a strobe light and disk and make manual adjustments hoping I get the right.

You can read up on the motor, controller etc; at the link below.

Turntable DC Motor System – BillThompson.us

 

[codyt]

Ah, nice! I like the motor idea. Need to read note about that. I’m also pairing my Pearl with a B1, though it’s in a separate chassis. Great, great combo imo

 

[McQuaide]

I asked Wayne about it. He thought it was a fine idea. In fact, didn’t the same change occur in the new 2018 line stage boards?

I've been running my Pearl 2 for a couple of weeks now "naked", meaning no output coupling caps (the DC offset is zero). It sounds distinctly better than with the caps. The top end is incredibly crisp, extended, and clear. I hate to use the cliché "a veil has been lifted", but a veil has been lifted.

 

[codyt]

I've been running my Pearl 2 for a couple of weeks now "naked", meaning no output coupling caps (the DC offset is zero). It sounds distinctly better than with the caps. The top end is incredibly crisp, extended, and clear. I hate to use the cliché "a veil has been lifted", but a veil has been lifted.

Great! That’s been my experience with this mod too.

 

[6L6]

Is the noise hum or popcorn/rush/white noise ?

 

[WBS]

...popcorn/rush/white noise...

Sounds like a flashback to my early 1970s days!

 

[avdesignguru]

So any ideas anyone, I have had other carts in my system & they were much quieter, so it may be something to do with the cart. I actually now have two AC-2's & they are both the same connected to the Pearl.
Cheers

This may be too obvious but have you added the 100 ohm resistor required for MC cartridges to position R20? You may also need more gain by replacing R14 with a lower value per Wayne's build guide.

 

[jackinnj]

This may be too obvious but have you added the 100 ohm resistor required for MC cartridges to position R20? You may also need more gain by replacing R14 with a lower value per Wayne's build guide.

50 Ohms minimum for the Acuphase AC2.

I wonder if genuine 2SK170/LSK170's were used, whether the power supply was built to spec. My Pearl 2 is extremely low noise and it mattered not whether built with the LMxx24, or with a Jung SR.

Copper foil is not as effective as a cookie tin, and two cookie tins like matryoshka dolls probably best. The ground plane of the Pearl is an antenna.

 

[McQuaide]

50 Ohms minimum for the Acuphase AC2.

I wonder if genuine 2SK170/LSK170's were used, whether the power supply was built to spec. My Pearl 2 is extremely low noise and it mattered not whether built with the LMxx24, or with a Jung SR.

Copper foil is not as effective as a cookie tin, and two cookie tins like matryoshka dolls probably best. The ground plane of the Pearl is an antenna.

His Pearl 2 used to be mine, and yes the Fets came from PassDIY. It has the Zobel on the input as well. Not sure what's going on with it and that cartridge, or what PS is connected.

 

[PhopsonNY]

Hi Codyt and McQuaide

I have followed with great interest in your elimination of Pearl2 output caps.
Is this simply a case of eliminating c13 with a wire and bypassing R14 with a lytic to achieve zero DC?

I would like to try this too.

tia

I've been running my Pearl 2 for a couple of weeks now "naked", meaning no output coupling caps (the DC offset is zero). It sounds distinctly better than with the caps. The top end is incredibly crisp, extended, and clear. I hate to use the cliché "a veil has been lifted", but a veil has been lifted.