Building a Pearl 2

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#401
Chryses -

The SL-1200, with just a bit of hot-rodding, will completely smoke any (and I mean any) VPI.

Rewire the arm, change the feet, get a good mat (not the stock, not a slipmat, not felt, basically any other, cork is great, and the Funk Firm Acromat is amazing), and make the PSU external. You will have a turntable that can hold it's own against any at any price, and completely dominate in the sub- $3000 category.

Yes, really. 🙂

Anyway, with your cartridge list I would wholeheartedly endorse the AT440mla. The 2M blue is also quite nice. If you can stretch to an AT150mlx you will likely never need, nor want to try, any other cartridge.

Lastly, I agree with Russell, skip the B1 and look into the BA-3 as pre, or something else.
 
#403
I'm starting my journey down this path as well. Just ordered all of the parts for a Pearl II as well as for modding my SL-1200. Immediate mods to include an external DC PSU, individual internal tracking pre-regulators for motor, motor control, a new 5v regulator for IC302, a new 9.4v regulator for IC301, strobe switch, single unbroken run of cardas litz wire from cartridge pins to RCAs into the Pearl, into a DCB1, then Aleph-J, to my new Tang Band 1772 speakers. I'll pick up feet and a new mat for the TT at some point in the near future. Also waiting for delivery on an AT150 cartridge.

Now all that I need is the time to build everything... Pearl II first, that way I can have an opportunity to listen to each of the mods!
 
#404
Russellc said:
Mine is in a DIY store chassis. I think some parts are steel, some aluminum. They were so close they may have been touching. This morning I played with it a little, and it is working quietly beside, but about 8-10 inches from the BA-3...it is also in a DIYstore chassis. This thing is dead quiet. No hiss, no hum, dead quiet. I have not tried it with my more efficient speakers, but I heard nothing even with ear right to speaker.

This thing is WAY sensitive (in terms of offset) to any air currents, breath, even through vents. My regulators (at least when I tried them after a few mins. of play were just warm, so I blocked off the vents...I will recheck today after extended play for temp. If it stays like it was, I may seek a non-vented "lid".

Note: dont try to adjust it under a ceiling fan like I did, you will get nowhere except freaked out.

When it was too close, there was a very pronounced HUM. You could hear music underneath, but buried by hum. I figured just a ground problem I would solve later today. I moved it on a lark before bed, and dead silence...which lead to me staying up way later than I should have!🙂

Russellc
Click to expand...

6L6 is right about transformers in proximity and absolute silence. When I first moved the BA-3 pre away from the Pearl2, it was by about 3 1/2 feet, and there was silence. Playing around yesterday, at the new 10 inches away position, I hear nothing at the listening position even at moderately loud levels, unless I get real close. Then I came hear a little bit of hum...again not at the listening position unless I turn volume way up, which is beyond where it would ever be.

I'm going to have to think about how things are arranged for a bit. At the 3 1/2 feet, BA-3 pre was sitting on top of F-5...kind of a warm position. Don't know if I want it there. Thinking of building another shelf underneath the wall mounted turntable shelf, which would allow plenty of room away from Pearl. Its not bad as is, but thing is capable of complete silence.

Even after 2 days play, Pearl is sounding better. More smooth with less of the "wiriness" I hear (or imagine I hear) with newly built components.


Russellc
 
#405
The Pearl 2, as designed, is problematic with Moving Magnet cartridges. In simulation, I derive an overload margin of only 15dB. (Defining overload margin as ratio of the input level at 1kHz which distorts the output to 1%, relative to 5mV). In the soldered up world of reality it is much worse.

I don't know how Wayne came up with the THD% chart in his article, I am seeing much worse results. The gain of the second section should be a lot lower for MM cartridges.
 
#406
jackinnj said:
The Pearl 2, as designed, is problematic with Moving Magnet cartridges. In simulation, I derive an overload margin of only 15dB. (Defining overload margin as ratio of the input level at 1kHz which distorts the output to 1%, relative to 5mV). In the soldered up world of reality it is much worse.

I don't know how Wayne came up with the THD% chart in his article, I am seeing much worse results. The gain of the second section should be a lot lower for MM cartridges.
Click to expand...

Very interested in hearing from Wayne and others on this issue. Just finished mine...sounds great, havent heard any complaints on sound. I know Jack knows his stuff, but so does Wayne...is it possible the simulation is flawed? That would be over my head. Someone with the know how and has one could measure maybe? Would like to hear the other shoe drop on this!

Russellc
 
#407
I have a power supply question

If I look at this correctly the Pearl 2 has an external unregulated power supply that feeds a regulated supply on the board for +/- 24V rails

Why not just have an external regulated supply at +/- 24V and bypass the on board regulation. Something like the AMB sigma22 or the Shunty from the Pumkin/Shunty?

Am I missing something or would this work just as well?

Debra
 
#408
The regulators will always work best when close to the load.

Most of the noise will be from the transformer itself and the switching noise of the diodes. Having that in the external box keeps the noise away, having the regulators close to the load helps with precision.

If you wanted to use the Sigma22, Shunty, or Salas LV shunt, by all means go for it - I've wanted to try a shunt regulator with the Pearl, but I have too many other projects to do...

Just make sure the transformer, bridge, and first filter caps (at a minimum) are in a separate enclosure.
 
#409
Russellc said:
6L6 is right about transformers in proximity and absolute silence.
Click to expand...

I think that the grounds and ground planes are behaving like radiators in this case.

Would like to see other's results -- my Pearl 2 is on Wayne's boards with a couple of minor tweaks to the RIAA network which I had mentioned previously. Instead of 7824/7924 I use LM317/337 because they are quieter (although the pinout is different). I also used the SuperRegulator hopped up to +/-24V with no appreciable difference.

I would sincerely like to see other's results. If no THD/distortion analyzer , an FFT with a soundcard would suffice.
 
#410
jackinnj said:
I think that the grounds and ground planes are behaving like radiators in this case.

Would like to see other's results -- my Pearl 2 is on Wayne's boards with a couple of minor tweaks to the RIAA network which I had mentioned previously. Instead of 7824/7924 I use LM317/337 because they are quieter (although the pinout is different). I also used the SuperRegulator hopped up to +/-24V with no appreciable difference.

I would sincerely like to see other's results. If no THD/distortion analyzer , an FFT with a soundcard would suffice.
Click to expand...

I dont have equipment of that nature unfortunately. I am also afraid that for me, you would have to "dumb down" the FFT with Soundcard part as well....likely I am not qualified but several here are I'm sure.

I would like to try the Shunty kit I got from Zen Mod, but I am waiting for a little more experience before I dive into that one...I'd have so many questions getting it right now, Zen Mod may fly over here and whip me with a stick!😀 Frankly, I dont know if it would be appropriate for Pearl, but once I get that supply running, I wont be so gun shy to finish Pumpkin part.

Russellc
 
#412
I had few (German ) guys buying Shunty(s) for (X)ono , where I calculated/edited both Shunty and (X)ono schmtcs to complement them

I believe these are files ......

I believe these guys aren't exactly Audiophools , saying that difference was , well , quite dramatic :rofl:

just to repeat my self ( for oomphteenth time ) :

-I prefer proper shunt reg to CRC (or , better , extensive CRCRCRCRblahblah);

- I prefer said CRC to any kind of series reg

disclaimer - in all cases where dissipation can stay in sane brackets
 

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#413
kamis said:
Super regulator made no difference in Pearl Two ? But they won your regulator sound quality test.
Click to expand...

The sound quality test was with Erno's "All JFET" line driver -- notably poor PSRR of only 40dB with a high end SACD player, not vinyl.


If y'all want to come over to NJ we can do a bake-off of various phono stages. I am afraid that the Linn LP12 that I use may not be up to the standards of the vinyl zealots (but it sounds great to me!).

As ZM makes clear, the Pearl 2 isn't an Aleph Ono, for MM they use a different input configuration.
 
#414
kamis said:
Snubber capacitor 0.22uf is very important part. I insert it in the same position in my Xono Diy phono , and difference in sound is huge. Manufactured Xono had ordinary diode bridges in PS without any snubber. Perhaps a part of Xp-15 and XP-25 sonic superiority over Xono is snubbers over diode bridges.
In my case, sound is now more focused, dynamic with more lowest level details. I am using cheap integrated bridges . Capacitors should be MKP X2 rated type for lowest ESR.
Click to expand...

What cap did you use for this position? All I am finding are "PC type" mount.
Little square boxes with very short legs, designed to mount to PC boards. If this is the type you used how did you mount these things? I found MKP caps, but dont say X2 rated...just axial film caps...should I not use them, they seemed to provide an improvement in focus, but I dont want to use something unsafe or improper.

I did mount them off the secondaries, not after the diodes as we discussed.

Thanks,

Russellc
 
#418
I use Arcoelectric R46 X2 rated capacitor for snubber. Leads are short, and should be prolonged with solid core wire. It is always desirable to use X2 rated capacitors before the bridge since they are better made than ordinary MKP caps.Take look at the snubber capacitor inside Pass XP-25 phono stage. It is a Panasonic 0.22 micro X2 rated capacitor.
 

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#420
Given all of the discussion about interference from power supplies lately, is it worth the additional cost ($140) for an RFI/EMI shielded chassis like this one: Par-Metal ?

Or should I just go with a more "standard" series ($70) that has holes in the lid and the same alodine finish: Par-Metal

Do the sinks in the regulator stage produce much heat that needs to be vented?
 
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