(Another) Pearl 2 Buiild

[jls001]

Update:
1) Did extensive reworking on the RCA sockets on the cabinet to insulate the shell of the RCA sockets from the chassis/cabinet. This was advised by Om. I would never have given a thought to such things.

2) Powered up the Pearl 2. Adjusted the DC offsets on both boards. It is tough to get near-zero values as the pot is ultra sensitive. Both channels are within 10 mV.

3) Played a few familiar tracks. Initially, it sounded like rubbish. Highs were recessed and details were missing and everything seemed like it was playing from below a thickish blanket. Now I'm on the fifth track and it has really started opening up and beginning to sound rather good.

4) Current cartridge is the Decca London Super Gold (MI) with a high-ish 5 mV of output. 'Table is TD 124 with SME 3009 Series II Unimproved arm. I was quite apprehensive that with such a high default gain of about 55 dB from the Pearl 2, whether the phono stage's output would saturate the rest of the chain. I'm glad a comfortable listening level with this cartridge is just about 6 dB below my regular listening level.

5) Will leave the Pearl 2 powered on and check and adjust the DC offset after 24 hours. Also the arm needs fine tuning as I can clearly hear IGD.

Red glow of the Pearl 2

 

[jls001]

Update:

1) Isolator circuit added to the PSU. This consists of a bridge rectifier 3510, one NTC 10 Ohm/10 Amps thermistor as per the "as built" diagram given below.

2) overall view with the isolator circuitry in place:

3) "as built" diagram for the PSU

PS: I guess that completes the physical part of the build. Top covers are now screwed down. I had checked the DC offset voltages last night and I found they have drifted off to +20 mV on one channel and and about +40 mV on the other channel. Same adjusted to within +20 mV. I'm leaving it at these numbers as the adjustment is very jumpy.

Now it is time to sit back and let it burn in for at least 25-30 hours before pronouncing judgement on performance.

 

[bhaskarcan]

Joshua, Great work.

Very nicely and neatly done and documented. Very good choice of accessories(cabinet, connectors, wire etc.).

Dc offset takes time to settle. Let it run for around 50/60 hours and then adjust again, should settle by then. Mine one took almost a month to settle down.

Also using the vertical multiple-turn trim-pot instead of the used horizontal type for offset adjustment would have given you more turns for same value. It makes it little easier to adjust the dc offset.

Pearl2 really holds up to the SQ of the Pass stable. Overall very warm sound with great detail. And as a bonus we found that coupled with Pass F5T it greatly reduces surface noise without disturbing the music at all. So hope you enjoy your built.

Regards,

Bhaskar

 

[keith_correa]

Joshua, what wire did you use for small signals?

 

[sachu888]

Nice build Joshua.I also need to add Bridge rectifier,pending since long.

Regards,
Sachin

 

[jls001]

Joshua, what wire did you use for small signals?

Toyo make RG-174 coaxial cable, 50 Ohms IF/RF cable. It is well shielded and flexible enough.

 

[jls001]

Joshua, Great work.

Very nicely and neatly done and documented. Very good choice of accessories(cabinet, connectors, wire etc.).

Thanks, Bhaskar.

I will change the power supply cabinet to something better when I have some time to go meet a cabinet wala. The one I am using now is made of a thin gauge of MS. It is not strong enough and flexes easily. It is cheap (Rs 100) and it shows

Dc offset takes time to settle. Let it run for around 50/60 hours and then adjust again, should settle by then. Mine one took almost a month to settle down.

I will check it up after a few days of keeping the unit continuously on.

Pearl2 really holds up to the SQ of the Pass stable. Overall very warm sound with great detail. And as a bonus we found that coupled with Pass F5T it greatly reduces surface noise without disturbing the music at all. So hope you enjoy your

My initial impressions of the Pearl 2 are positive.

The F5 Turbo ver 2 is next project. I will have to find source for good capacitors and heatsink. I will also need to buy 1 - 1.2 kVA toroidal. Rest already received from Sachin.

 

[sachu888]

The F5 Turbo ver 2 is next project. I will have to find source for good capacitors and heatsink. I will also need to buy 1 - 1.2 kVA toroidal. Rest already received from Sachin.

Contact Om for heatsinks.I think he is planning to build another F5 with bigger heatsinks.Take time for caps as they affect the SQ.Tortrans Pune offers better price for transformers.

Regards,
Sachin

 

[jls001]

Minor update:
1) I have been running the Decca London Super Gold cartridge on the new Pearl 2. However, there is some distortion in the mids which I thought could be due to poor alignment. I re-did alignment of nulls and overhang, but that didn't change the sound.

2) I swapped it out with another cartridge (Denon DL 160) and it is singing sweetly. So I may have a problem with my Decca London.

3) I have not heard the Pearl 2 with any MC cartridge. So I changed the impedancxe loading to 330 Ohms and played the ZYX RS 30-02 cartridge through the L75 'table. I have not changed the resistor for the gain (R14) so it is running at the default gain of 55 dB. For the 0.24 mV output of the cartridge, 55 dB is insufficient. So I end up jacking up the gain in the line stage. It needs about 15 dB of extra gain in the line stage to get the same level of loudness. At this high gain, without the needle dropping on the record, it is complete silence even when pressing one's ear to the woofer. Very commendable.

4) I think this phonostage deserves a means to dial in the impedance loading, gain and capacitive loading. All from the front panel, using knobs.

5) This phonostage will eventually have to face off with the Hypnotoad AD 797 phonostage using an MC cartridge, as that is the other available phonostage.

 

[sann]

4) I think this phonostage deserves a means to dial in the impedance loading, gain and capacitive loading. All from the front panel, using knobs.

+1 , badly needed.

 

[bhaskarcan]

Minor update:
1) I have been running the Decca London Super Gold cartridge on the new Pearl 2. However, there is some distortion in the mids which I thought could be due to poor alignment. I re-did alignment of nulls and overhang, but that didn't change the sound.
....................................

IMHO Decca London is an excellent cart but equally difficult to setup properly. Even tonearm matching is also one of the most difficult one. So it's better to setup a new equipment with relatively straight for'd cartridge. So at least you know where the problem is. Once you are satisfied with your pearl2 then you can re-introduce the Decca London in the chain.

My 2 cents.

Bhaskar

 

[jls001]

Same switches of MM/MC could be used by single selection of SPDT switch. If you need to implement please let me know. I have some thoughts on it.

@Omishra: can we give this a serious thought? I have been trying to get both MM and MC flavours and luckily I had put a terminal block with screw across R20 (=R*) so that I can insert an appropriate resistor for MC cartridges. But to make it flexible, we probably need a front panel (stereo) selector for various impedance loads (like 50, 100, 200, 400, 1000, 2000, 33k, 47k, 67 or 70k).

Another possible area of improvement is the gain setting. I didn't put screw type terminal blocks across R14 so I am left with no choice but to use default gain. I cleverly put terminal blocks across R15 (=Rx) where it is not really required as it needs just shorting. I think I will correct this mistake and put a terminal block across R14 to be able to swap out different values of resistors for higher gain. I will have to first remove the terminal block across R15 as there isn't sufficient space for both.

We probably need 4-way switch for gain selector.

Yet another area of improvement could be for capacitive loading. Here too, may be we need 4-5 values.

 

[jls001]

1) Bridge rectifier 3510 (like this)

2) NTC 10 Ohms, 10 Amps (like this)

Since I cannibalised the above parts from another yet-to-be-started project, I had to replenish them.

The 3510 is fairly easily available and costs just Rs 24 per piece. If you want to buy for a huge, huge markup, try element14.in

The NTC is 10 rupees per piece.

Both are worth stocking for future projects, so I bought more than just replenishment quantity.

 

[jls001]

2) I swapped it out with another cartridge (Denon DL 160) and it is singing sweetly. So I may have a problem with my Decca London.

I am very happy to report that the trouble with what I thought was due to the Decca cartridge is not due to the cartridge. It was due to a loose bearing in my tonearm. It had an audible adverse effect on the Decca, probably because the Decca has no form of in-built damping. The Denon DL 160 wasn't affected by the problem in the arm. I have repaired the arm and the Decca is back on duty.

Initial impressions of the cart with the Pearl 2 is that it has wonderful tonality, but somehow the highs seemed slightly recessed from what I am used to hearing from this cartridge. Let me see if I can improve the sound by fine tuning the alignment. I adjusted the overhang but not the nulls. Also, the tracking weight is a wee bit more than the recommended 1.8 grams. On an arm without calibrated counterweight, the final fine adjustment can sometimes be quite dreadful and repetitive.

 

[jls001]

but somehow the highs seemed slightly recessed from what I am used to hearing from this cartridge.

I thought I licked the problem with the tonearm, but it has re-surfaced. The symptom is a slight distortion in the mid range. Highs and lows are clean.

So the Decca got transplanted to the second deck and it is reassuring to hear once more the pristine and fluid highs of the Decca London Super Gold. I guess the arm needs more than band-aid repair.

Immediately after removing the Decca from the affected arm, I mounted the ZYX RS30-02 and it plays without any audible distortion. This very minor fault is enough to distort the Decca but the ZYX can handle it as it has damped suspension. So this is a negative mark for the Decca despite its other strengths.

I think I have put in enough hours on the Pearl 2. So it is time to listen critically and swap out other cartridges for comparison. So far I have heard the Pearl 2 mainly with the Denon DL 160 and to a lesser extent with the Decca. So far I like what I'm hearing. I will swap out a resistor in Pearl 2 to increase the gain to start listening to LOMCs.

 

[jls001]

A formal review as threatened/promised :

First off, the timbre and the tonality from Pearl 2 is just beautiful. It is a pleasure to listen to piano and violin concertos or small jazz ensembles with sax leads, or massed trumpets suddenly crescendo-ing in anger (as in Michael Buble's All of Me from the album Crazy). The woody resonance of the acoustic piano, or the bites in the violin solo, or in the tenor sax or in the brass section - sends tingly feelings down the spine. Nothing is glossed over or smoothed out. It also has the jump factor when called for (like the palpable and "in-the-room" Max Roach drum solo on the track "St Thomas" from Sonny Rollins' Saxaphone Collossus album; or the spooky presence of William Gomez's "Juex Interdits" from his "A Guitar Recital" album). Sure fools the brain into almost believing that it is being played in the room.


Frequency response across the audio band is quite balanced. The mids can probably be termed as being on the warmer side of neutral. Highs are crystal clear and liquid (with the Decca London Super Gold cartridge). Lows are covered well, too. The leading edge of notes are swift and trailing edges decay nicely, and is especially audible on the sound of hi-hats.


The whole analog chain is responsible for how well details are dug out from record grooves. Unexpected aspects of the setup seem to influence unexpected aspects of the sound (like the slight play in the tonearm bearing that has been bothering me by introducing a light distortion in the mid range and rolling off the highs). This balance is rather delicate and an imbalance can lead to much head scratching and sniffing around. But when harmony prevails, the Pearl 2, by virtue of being a very low noise phono stage, with a low noise floor, can dig out the low level details in recordings. In the past few days, I have heard a lot of the proverbial new details in familiar music. But there is downside here - what I thought were listenable records are suddenly sounding less than good. It surely doesn't gloss over poor recordings.

It is quite capable of dynamic peaks without sounding compressed.

Spatially, the soundstage is fairly laid back than I would have expected from reading descriptions by other builders. The sound "plane" is well behind the front baffle of the speakers. May be 3 to 4 foot, if I am allowed to guess. It sounds as laid back as any other phono stage I have heard in my room. There is good left-right spread which is nearly out-of-speaker. Voices are stable and locked to a position. Layering is good and one can hear multiple layers of voices in the front to back space. Following individual voices is also easy (like the frantic strike of the cymbal in Dire Straits' Sultans of Swing (from their debut, self-titled album).


A standout character is the low surface noise, though ticks can still be heard on bad records. Low surface hiss is truly welcome. I totally concur with Omishra's observation on this aspect.

It is also musically involving. I was listening to a David Sanborn album, hoping to glean some nuggets of information. I came away totally blank as I got immersed in the music. I forgot what I'd set out to do.


Those are the general impressions. I hope to pen some more impressions on how different cartridges sound with the Pearl 2, and also do a brief comparo with the incumbent phonostage - the Hypnotoad AD 797. Thanks for reading.


I built the Pearl 2 with the hope that it will be a better phono stage than my current best MM phono stage. That has surely been fulfilled.

 

[captrajesh]

Thank you for the superb review; it looks as professional as a review can get.

 

[murali_n]

I built the Pearl 2 with the hope that it will be a better phono stage than my current best MM phono stage. That has surely been fulfilled.

Hi,

Can you elaborate on this?

Thanks,

N.Murali

 

[jls001]

Hi,

Can you elaborate on this?

Thanks,

N.Murali

I needed a phono stage that will make the Decca cartridge sound at least as good as the best MC cartridge I have at hand when running the best MC pre I have at hand (AD 797 phono preamp).

To elaborate a bit further, my original phono stage (Musical Surroundings' Phonomena), though a very good all-round phono preamp with adjustible gain, resistive and capacitive loading and can handle both MMs and MCs, doesn't give me as good a sound as the MC phonos that I have.

I built the CNC MM phono pre hoping to better the Phonomena. It didn't.

In the meantime, the first version of Hypnotoad came along. It bettered the MC performance of the Phonomena. Then ver 2 (AD 797) came and bettered the ver 1 in every meaningful way. So the bar for MM-capable phono pre was raised substantially. With the reputation the Pearl 2 has built up, I thought it could be the ticket for me to MM heaven.

 

[jls001]

To begin with cartridge comparisons....

I have swapped out to an MC cartridge (ZYX RS 30-02) to understand how the Pearl 2 sounds with an MC. Only cartridge is changed, everything else is constant (except for changed resistive loading in Pearl 2). Prior to this, the bulk of my listening was using the Decca London Super Gold cartridge

The ZYX has lots of similarities with the Decca.

First of all, it is also a very dynamic and pacy cartridge, so their overall sound is similar.

Where they differ is in the refinement of the highs - the Decca is a few classes above the ZYX in this department. The Decca sparkles and shimmers. The ZYX does that too, but to a much lower degree. In fact it sounds kinda veiled compared to the Decca. This is a relative statement - on its own, you won't find the treble performance of the ZYX lacking much. It is only when compared to a better cartridge that weaknesses show up.

The Decca is also a class above in the midrange performance. In fact it sounds warmer than the ZYX, which may seem counterintuitive, given the fact that the Decca produces a lot more treble energy.

The ZYX, however, covers the bottom octave much better than the Decca. It has more weight, though not necessarily better definition.

The Decca is overall the better cartridge. It has larger and better lateral imaging, better defined image depth, and a greater sense of liveliness and involvement. The usual caveat about using it on a well damped tonearm applies, though I do not have such an arm to try it on.