Polishing a Pearl?

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Buhl

Buhl

Member
Joined 2002
#1
Hi Everyone
Years ago, I built 3 of Waynes wonderfull Pearl phonostages - the original one. One for myself, and two for good buddies of mine. Alle are enjoyed greatly to this day. But I came to think if there was anything that could be done to improve them? I remember years ago there were a "Top 10 ways to better an Aleph" kind of thread, just for the Pearl?

I don't really need the Pearl 2 as I have an excellent SUT for my MC cartridge, and they look to fairly similar in parts? Anyone built both and compared thoroughly?

But the PSU in Pearl 2 is more "advanced" and also incorporates more info on grounding - would this be a benefit? Also, the BA2018 linestage PSU is an example of more RC-joints in the PSU, would this be worth exploring? Are there better parts for the JFETS than the ones originally used (probably not as they were the "right" Toshiba parts)?

Best regards
Hans
 
#2
I would have a look at the Mini (Minnie?) Pearl thread. Jack made an SMD version of the Pearl II without onboard PSU and some extra attention paid to ground and routing. If nothing else, there’s quite a bit of good discussion about parts and circuit in that thread.
 
#3
Buhl said:
Anyone built both and compared thoroughly?

But the PSU in Pearl 2 is more "advanced" and also incorporates more info on grounding - would this be a benefit? Also, the BA2018 linestage PSU is an example of more RC-joints in the PSU, would this be worth exploring? Are there better parts for the JFETS than the ones originally used (probably not as they were the "right" Toshiba parts)?
Click to expand...
Pretty sure @6L6 has both the original Pearl and the II.

PSU for the Pearl II has both V+/V- rails, so not compatible with the Pearl 1.

jeff
 
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#4
I actually have neither anymore, and for the life of me I can’t remember why I sold either of them. Fantastic phonostages both.

Very similar in sound, as the 2 is not all that different from the 1. Is the 2 “more advanced”? I suppose you could argue that it is, but you could also say the opposite. Most importantly, the input stage is identical between the two, (if it ain’t broke, don’t fix it!) and they are single-stage RIAA. The major differences are the 2 has a +/- (bipolar) supply instead of a single rail, which in turn changes the on-board regulators, and the output stage is a little more complex to allow for more gain, which was the biggest design goal of the 2. This complexity is a couple of constant current sources that leverage the bipolar PSU, but the output stage is also very, very similar to the original’s…


BA2018 is a linestage, it’s wonderful, and if you are interest in building one I can highly recommend it, you’ll be quite pleased. It uses current-production Toshiba Jfets, so they are the ‘right’ ones.

As for phono, Jack’s mini Pearl is absolutely worth looking at, and there is also something currently in the works, uses in-production Toshiba transistors (both Jfet and bipolar), and has some outstanding and interesting topological differences and options to make it a very flexible and high-quality phonostage.

😎
 
#9
6L6 said:
I actually have neither anymore, and for the life of me I can’t remember why I sold either of them. Fantastic phonostages both.

Very similar in sound, as the 2 is not all that different from the 1. Is the 2 “more advanced”? I suppose you could argue that it is, but you could also say the opposite. Most importantly, the input stage is identical between the two, (if it ain’t broke, don’t fix it!) and they are single-stage RIAA. The major differences are the 2 has a +/- (bipolar) supply instead of a single rail, which in turn changes the on-board regulators, and the output stage is a little more complex to allow for more gain, which was the biggest design goal of the 2. This complexity is a couple of constant current sources that leverage the bipolar PSU, but the output stage is also very, very similar to the original’s…


BA2018 is a linestage, it’s wonderful, and if you are interest in building one I can highly recommend it, you’ll be quite pleased. It uses current-production Toshiba Jfets, so they are the ‘right’ ones.

As for phono, Jack’s mini Pearl is absolutely worth looking at, and there is also something currently in the works, uses in-production Toshiba transistors (both Jfet and bipolar), and has some outstanding and interesting topological differences and options to make it a very flexible and high-quality phonostage.

😎
Click to expand...
Something in the works? Now you've got me really curious! The Pass Pearl 3? I need another project 😀
 
#10
If you are aching for a new phono pre to try, build the ultra folded phono creation of X's. Something to hold you over until Pass Pearl3. As to the original Pearl improvement, I think I have seen a few folks using his Ubib shunt power supplies on a Pearl. I do not own a Pearl, do have Pearl 2.

Russellc
 
#11
Thanks for your comments everyone - I will look into both the grounding around the PCB's as to the Pearl2 article, but also see if I can find a Ubib shunt PCB for sale and mock up one of those.

My Pearl have been sitting on a shelf for the past couple of years while my Mark Levinson 28 pre have done the RIAA work, but after getting an Auditorium23 step-up for my DL103 and hearing them together with the Pearl it's really a "step-up" (pardon the pun) to the ML28 MC stage, especially in the high range/ambience department - so it makes one curious to if I could improve the old Pearl further as I can hear some hiss 🙂
 
#13
I tip my hat to Wayne, and offered the Mini Pearl boards at cost in respect of his and NP's IP. I used a 4-layer board to minimize the ground-pickup effect.

The name refers to the Memphis "Grand Ol Oprey" comedian-star "Minnie Pearl".

Work with the Texas Instruments JFE2140 JFET's is not going well to be frank. While I can confirm TXN noise specs, the Idss is more akin to a high Idss 2SK170C.

NacSemi and now DK and others carry the LinearSystems LSK389A which is a dual low Idss which works with minimal modifications.

I would encourage all to try the Pearl II in its original version. A wonderful phono-pre for MC carts. Me, I have way too many phono pre-pre's.
 
#14
I’m considering building the Pearl II phono stage and going through the BOM from Pass DIY and putting together a parts order. I’m having an issue sourcing or finding a cross reference for U2 which is the NJR7924FA regulator. Does anyone have any suggestions what I can use instead? Digikey actually has the U1 NJR7824FA regulators in stock. Thank you in advance.
 
#18
I have the Sigma 78 and 79 regulators from amb.org in my Pearl II. Pin compatible with the 7x24 regulators. Lower noise, but more expensive and requires you to solder a few SMD parts. Not always easy, especially the tiny resistors (order a few spares). Since the output capacitor is max 25V I calculated them for a little under 24V (23.5 or something like that).
 
#19
Usually you add an SUT to a standard phono preamp. Using the SUT with a MC pre is adding more gain than you usually need. You might look at the gain structure of you system and how much you really need. Unnecessary gain will increase noise levels.
 
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