The Phonoclone and VSPS PCB Help Desk

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A

AndrewT

R.I.P.
Joined 2004
Mr Onion said:
................. Does the quality of the caps matter?
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Not directly. They must meet specification.

What is far more important is that the correct TYPE and value MUST be SELECTED to suit the duty, where they are expected to perform.

It is no good putting in a very high cost polar electrolytic where it has to handle significant AC or reverse voltage.

It is no good putting in a high cost silver foil cap where the signal is many tens of amperes.
 
vulejov

vulejov

Member
Joined 2010
dimkasta said:
By the way, how come the VSPS C2 is 3nF and not 2.9nF like in PC3?

I m going to match all the components, so...
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I experimented a lot with the values ​​in the RIAA network.. differences of a few tenths of a dB are inaudible..
But, C1 and C2 earlier was Wima MKP-10, now is Wima FKP-2.. I didn't hear any difference.. two friends who listened both versions said that FKP sounds better..
 
M

Mr Onion

Member
Joined 2012
vulejov said:
AD797 and LME49710 at position of the first chip certainly oscillate.. constructor was imagined that Phonoclone work only with impotent opamp.. AD797 will certainly work better and in the first position, try to put a capacitor in parallel with R2, start with 10pF..
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OK, I have spent all morning on this, and wish I hadn't.

I have put AD797's as IC1 with various bypass caps across R2, and THEY WILL NOT WORK in that position with my cart.

Today I had no output from the PC3 at all with 797's as IC1 no matter what I tried.

... and believe me I tried. You may (will) not agree with me, but my findings are as follows:-

Mr Onion said:
OK, here we go. TT is a LP12 with Ittok LVIII and DV XX2 MKII. Gain and load resistors set correctly as per the calculator.

The LME49710 in IC's 2, 3 and 4 gave a noticeable improvement to all areas of the music. Replacing IC 2 with the AD797 was even better. Clearer, lower noise, easier to follow.

Replacing IC 1 was a different matter. Both the LME49710 and AD797 were useless. The sound became thin, muffled, VERY quiet. Almost like a MM cart put in a line input. There is no way I am keeping them in that position. Putting the OPA27 back in IC 1 restored the music.

My recommendation (for what its worth) OPA27 in IC1, AD797 in IC2 and LME49710 in IC3 & 4.

No, I didn't try AD797's in IC3&4 as I didn't have enough to do both channels
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I repeat, with my cart AD797's WILL NOT WORK
 
A

andykap

Member
Joined 2011
-Mr Onion-
What cart are you using?
If you have a pair of LT1028 try them in IC1. The sound better to me. I am using a Denon 103r, and like you no matter what bypass I used for IC1, the AD797 will not work. I also agree that the LME49710 sound is horrible.

I just got some LT1128 and AD134 that I will try when I get home from work. I will try the LME40710 in IC 3 and 4.
 
vulejov

vulejov

Member
Joined 2010
Mr Onion said:
Richard has confirmed that R1 and R2 are correct for my cartridge in the PC3. I was not sure so I double checked with Richard that 6R and 215R are correct.
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Then you're doomed to use OPA27..
No matter which chip you use, it is not wise to load it with resistance smaller than 1k..
If you have too much gain, increase R3 and R4 to 3k9, R2-1k and R1-47R, and put 220-470p on R2.. you'll hear the difference even with OPA27..

Either way, PC3 is quite bad design.. VSPS is a much better solution, especially that can also be used for the MC..
 
T

Toaster

Member
Joined 2004
In your opinion, in your system, you may prefer a different design approach, but the PC 3 a 'bad design'? My ears tell me otherwise, in the context of an extremely good turntable in a revealing system with a wide range of music. For those reading this thread, don't be put off by this kind of absolutism; the PC in standard form, with no chip rolling, is an excellent sounding bit of kit.
 
M

Mr Onion

Member
Joined 2012
Toaster said:
In your opinion, in your system, you may prefer a different design approach, but the PC 3 a 'bad design'? My ears tell me otherwise, in the context of an extremely good turntable in a revealing system with a wide range of music. For those reading this thread, don't be put off by this kind of absolutism; the PC in standard form, with no chip rolling, is an excellent sounding bit of kit.
Click to expand...

Thanks for confirming that I haven't got cloth ears. The PC3 built with the BoM holds its head high. Its better than my previous Phono Stages, the Dynavector P75 II which was better than the NAIM Stageline. Put some LME49710 in IC 3 & 4, and a AD797 in IC 2 and it's even better although I still have the 'poor sounding' OPA27 as IC 1.

I recon I'll have to spend around £2k5 to get a significantly better sound (Urika in my LP12) but that will be a while coming. As it is I have no plans to change the PC3 in the near future.

This is in the context of a £25k system, with the PC3 being the cheapest component in the Vinyl replay chain.

For the moment I am given up messing with the board, and I'm listening to music instead.
 
dimkasta

dimkasta

Member
Joined 2010
I agree

As for the AD797, I just installed 50pF ceramics between pins 8 and the ouput (before the cap) on my vsps
The difference is not subtle... Imaging, depth and instrument separation are through the roof... And bass is significantly more present. I wonder how this would work if I moved R6 after C3 and moved the 50pF to include C3 in its loop as well...
 
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T

Toaster

Member
Joined 2004
In terms of measurable improvements? Meaningless to talk about technical improvements otherwise. 'Bad design' needs to be quantified, or better yet stated more politely, particularly on the designer's build thread! Only relevant if it translates to better SQ in any event. I'm not arguing against experiment- this is DIY Audio after all- but there is a danger of overstating differences here, not to mention devaluing a really fine, inexpensive, well supported design. Nothing wrong with your ears Mr Onion. The PC here has been run with the Townshend Rock 2 and laterly with the Trans-fi Salvation rim-drive deck and the T3 air-bearing tonearm. Cartridges used include the AT OC-9, an Expert Stylus retipped, metal bodied Denon DL110R and an Ortofon A90. The rest of the system is mostly DIY and includes Pass F5s driving active speakers. If the design was 'bad' the RAAL tweeters would let you know. Cost to performance is off the chart- about the only thing I can think of that is in the same league is a good secondhand Lenco L75 turntable.
 
dimkasta

dimkasta

Member
Joined 2010
vulejov said:
Absolutely there is no logic to improve bass reproduction by adding 50p to pin8..

Impression while listening device is highly subjective, that is why you should not be taken seriously..
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And yet here it is...

I never claimed that my impressions should be considered as subjective... I am just reporting stuff I notice in my system...
It is a very simple trial and I have no benefit from it.... I do not sell the 50pF caps...
Others on the other hand can benefit from it.

On the other hand, you were claiming that pin 8 compensation has no effect in our case, in straight contradiction to the datasheet and my testing, and now you are trying to make me look like a fool to justify your previous statements...

Please relax your tone...
 
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