Phonoclone 3

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rjm

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Forum member peranders has decided to mediate between Rhys and the hordes of angry people who were in on the many different group buys Rhys was running.

I was trying to keep a record of the phonoclone 3 subset, but once it became clear that only about 10-20% of the orders were actually fulfilled there wasn't much else I could do ... I have no more influence over Rhys than you guys do. Hopefully peranders does.

I suggest emailing peranders with the details of your order: what you ordered, how much you paid and when you paid, and what if anything you received. Then cross your fingers and hope...

The wiki is here:

http://www.diyaudio.com/wiki/index.php?page=BPA300+Group+Buy+Round+2

/rjm
 
I have finally finished my P3 after a few stuff ups with one board. The good news is that nothing seems to have been damaged in spite of it.

The power supply is 80VA toroid with dual rectifiers. I have hardwired the phono leads out with DH Audio silver interconnect.

I’m using a ATF9 II (20 ohm, 0.4V) with a R1/R2 of 20/520 ohm metal film. I plan on changing to better quality carbon film when I can. After a few hours it’s quite a bit better than my Musical Fidelity V3.
I also have a DL103R which I haven't tried as yet. Since getting the AT, I much prefer it to the 103R but will try later. Plan is to make another soon.
Hope Rhys gets his kits out.

Kffern
 
I have gone through a few LP's today and compared the MF V3 and realised that the background noise is higher on the P3.

I have 2 arms on my Lenco L75 and one connected to each phono preamp which are both connected to the preamp. I'm listening on headphones and switching between the 2 at listening level (9 o'clock) the P3 is just audible and the MF is silent. The MF is only audible at 12 o'clock position.

Am I doing a fair comparison? Can I expect better from the P3? Where do I start?

Either way once the needle hits the vinyl the MF falls way behind. I have even tried played both arms at once and switching between the 2. I had a 103R on the Micro Seiki M505 and a AT F5 on the Technoarm. I will put a AT F9 on the Technoarm later for a better comparison.

Any advice welcome.
Kffern
 
maybe you can test the following: comparing the noise from connecting preferrably the same cartridge through the different phono stages at a level (these levels may be different for both phonestages) that normally is the loudest you use, but then without lowering the cartridge to the vinyl.

A logaritmic volume control is progressing slower near the max setting, and your ears are pretty sensitive for recogizing this max level so this test may be more accurate.

Of course a real measurement would be better ...
 
maybe you can test the following: comparing the noise from connecting preferrably the same cartridge through the different phono stages at a level (these levels may be different for both phonestages) that normally is the loudest you use, but then without lowering the cartridge to the vinyl.

I thought this is what I have done already before I tried messing about with the 2 arms on different phono stages.
 
Musical Fidelity X-LPS V3 MM/MC Phonostage (This is yours ???)

SPECS:

MC input
Sensitivity:> 350µV for 350mV output at 1kHz
Input impedance: 100 Ohms
THD: < 0.01% at 1kHz, 350mV out
Input overload margin: 30dB
Signal / Noise ratio: > 65dB unweighted > 74dB 'A' weighted


So gain is 1000 not sure what the gain of your PC3 is.

Noise level is not spectacularly low, so PC3 should be able to beat that.
 
You don't describe the type of 'noise'. Is it just an awareness that something is turned on, or is it a specific type of noise? Is the earthing identical on both arm/cartridge combinations? Are you using the same phono cable between pre amp and P3? And the same preamp input?


I ask the above to narrow down the possibilities - however it seems to me that the comparisons which you have made do not allow for the many variables between the two arm/cartridge/wiring combinations.

I think that you should stick to one arm, one cartridge and one set of leads. I know too well that eg to change even between exact same type items at this end of the chain can have an enormous subjective difference. The best example of close match I had was when delighted with a Fidelity Research FR 64S arm, I bought the slightly lower mass 64FX(?) for use on a second TT. Using the same Ortofon SPU the subjective difference in tonality and noise was greatly in favour of the 64S type - which had different wiring and slightly different mass. I then put that arm in the same arm collar on the second deck and the magic was restored! THe design and dimensions of both arms are I believe identical.

If you then think that the P3 is noisy, try and get it as close as you can to the PU arm, with the shortest possible leadouts from the arm. Then orientate it for the lowest noise - if there is any. THen do exactly the same with the MF unit in place of the P3.

What the P£ may in fact have done is highlight a previously unsuspected problem elsewhere in your system/setup.
 
however it seems to me that the comparisons which you have made do not allow for the many variables between the two arm/cartridge/wiring combinations.

I think my mention of later using both arms has confused the issue.

My initial observation with the P3 was made with the same arm/cartridge combination as the MF. The only variable was the phono lead which in the case of the P3 is DH labs BL-1 hardwired to the board and shield connected to earth at the preamp end. The MF was connected with a home made VDH D102-III with shield to ground one end.
I guess that will be my first line of attack - connect the shield at source / disconnect shield or just fit phono plugs ?

I did use both arms with both phono stages with the same observations.

You don't describe the type of 'noise'.
The kind of noise you get when you turn up the volume to max with any MC phono stage - a kind of electronic hash is the only way I can describe it.
I will hook it up to another system (Bryston) first and check tomorrow.

Thanks,
Kffern
 

rjm

Member
Joined 2004
Paid Member
On noise:

Some while ago I posted the noise output of my phonoclone 3.

phonoclone_noise_2496_new_54.wav

Download it and give it a listen. Your noise should sound like this, more or less. The absolute volume will depend on a number of things, so don't worry about that so much as the character of the sound.

Without getting technical, just consider the phonoclone 3 noise on its own, in the following way:

Is it completely silent at normal listening levels?
Is the noise at high volume settings free from hum on buzz?

A correctly working phonoclone 3 should return affirmative to both queries.

Getting (a little) technical, looking at the v8 X-LPS specs, the gain is 60 dB, the S/N is given as >100dB A-weighted. If you've set the phonoclone gain to 60 dB as suggested in the worksheet, the noise levels should be very comparable unless the X-LPS uses a discrete transistor input stage ... which it very well might ... or you've messed up the phonoclone in some way... which is unlikely if it sounds fine and is quiet at normal listening levels.

Got all that? :)

/R

P.S. the phonoclone 3 output noise is the datasheet value for the OP27, i.e. the only way to do significantly better is to use a lower noise device for the input stage. Changing the power supply / regulation / filtering / bypass / circuit values cannot lower the noise further. You can't do much better than the OP27 when it comes to op-amps, the obvious road is instead to move to discrete transistors, low noise JFETs typically.
 
I rechecked my noise level again and when I disconnect the headshell the noise is very very low: I can cannot hear any noise from the speakers at 3.5 meter normal distance at a very high volume level that I rarely use at all.(really very loud!!)

However when I reconnect the headshell I just can hear a little noise under the same conditions.

I am using a DL304. Anybody able to explain why connecting the cartridge increases the noise level?

By the way I am also looking for a nice binding post on the PC3 for the earth connection of the cartridge.
Any suggestions?
 

rjm

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Joined 2004
Paid Member
JBdV said:
Anybody able to explain why connecting the cartridge increases the noise level?

The cartridge sets the gain, remember.

Noise is proportional to circuit gain, and the phonoclone circuit gain is the sum of the output stage (30dB) and the input stage, 20log(R2/cartridge Z), normally also 30 dB..

Removing the cartridge makes the first stage gain nominally zero (-inf dB), and the circuit noise falls by 30 dB to be defined by the output stage op-amp only.

/rjm

P.S. Heading off a question that would naturally arise from my previous post on noise: If a transistor input stage would have lower noise, why don't we add a transistor input stage to the phonoclone?

While the input transistor would have a device noise lower than the input transistors of the OP27 or similar, the trick is designing the transistor input stage to have comparable stability, PSRR, CMRR, and distortion characteristics to the op amp. I'm always open to ideas, but I seems to me this would be relatively difficult. I'm not familiar enough with transistor amplifiers to be able to design such a thing, at any rate.
 
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