The Phonoclone and VSPS PCB Help Desk

[richandy]

-Richard,

In an earlier post you had a wave file that has how the noise level of the PC3 sound like. Unfortunately the link is dead. Do you still have it? If so, can you upload it again? I want to compare my noise with yours as reference.

~Richard

 

[fap]

G'day all, another RIAA related question that someone might venture an opinion on. As the VSPS is essentially a 'full feedback' op amp design, this particular circuit approach seems to be prone to an issue that I've conclusively proved that happens, that is exaggerated audibility of record scratch etc.

Other phono stages I possess that utilise passive treble equalisation seem to be quite free of this issue. From what I've read this issue seems to be a consequence of transient intermodulation effects in the feedback loop of the op amp voltage amplifier stage.

Other builders of the VSPS have apparently also noted the same issue from what I've read. That's a real pity actually as I rather like the sound of the VSPS, but the exaggerated click audibility is a real turn off in my opinion. Regards, Felix.

 

[vulejov]

Since a couple LT1028 is unused, I plan to make and try a simple MC phono..

Does anyone here saved older mono version Eagle files of VSPS PCB.. one layer with 78/79 or LM 317/337 stabilizers..

 

[vulejov]

Final version.. idea is to see how single chip works.. 60-65 dB should not be the problem..

 

[vulejov]

Find it, something like this would be good enough.. remodeled scheme, I completely forgot that now using positive input ..

 

[richandy]

Find it, something like this would be good enough.. remodeled scheme, I completely forgot that now using positive input ..

How does it compare to the two op-amp version?

 

[vulejov]

This is two opamp phono that I use..

I want to try single chip version, with the idea that will be less distorsion.. or that with more gain opamp work better.. I think that 60-65 dB gain should not be a problem..

 

[bucurb]

May be most of you did read this paper:
Op amps in small-signal audio design - Part 1: Op amp history, properties | EE Times

 

[Carlp]

Vulejoy,

I'm interested but confused. You say one chip op-amp, yet your last schematic shows 2 chips. Is that the one you're currently using, and you want to try a single op-amp version with LT1028 alone?

 

[vulejov]

Vulejoy,

I'm interested but confused. You say one chip op-amp, yet your last schematic shows 2 chips. Is that the one you're currently using, and you want to try a single op-amp version with LT1028 alone?

That's right..
I will try single opamp version with LT1028.. I would also try AD797, it should work even better..

 

[bucurb]

@Vulejov,
What about LME49710HA compared to AD797, please.

 

[vulejov]

@Vulejov,
What about LME49710HA compared to AD797, please.

Low noise..

 

[bucurb]

AD 797

Thank you very much, I did order several AD797. I'll try this opamp on my VSPS300 (DIP8, it's very simple) and will compare it against a manufactured one (not mine).

 

[vulejov]

Thank you very much, I did order several AD797..

My phono is designed for the MC cartridge, so I choose opamp according with that..

I just borrowed VSPS board, because the structure is same and uses a single chip..

PCB have lot of space for RIAA network capacitors.. thinking to use Wima FKP-1, for that purpose small correction of value..

 

[tralalalala]

Will Use Two Separate Power Supplies: Two separate chassis or just one?

Hello,

Maybe a silly question...

I just ordered a Phonoclone kit! This will be the most challenging project for me so far I´ve just done kits and upgrade kits before with everything included..

I a really looking forward to this job...

I just ordered two chassis from this site in Italy: modushop.biz

I ordered
one chassis 230x230mm ( for the phono clone boards )
and
one chassis : 230x330mm ( for two separate power supplies )

So maybe I messed up, is it possible to install two separate power supplies in one chassis - or will I need two separate boxes?

 

[Mr Onion]

Is it worth changing PhonoClone's IC 3&4 as they are in the Power Supply side?

My PC is built to the BoM with the addition of caps on the input sockets and IC PS pins.

Anyone?

 

[vulejov]

Presumption that opamp works better whith more gain proved to be true..

Single-opamp version sounds better than two stage.. LT1028 easily deals with 65 dB gain..

These days I'll try AD797, I expect to be even better..

 

[dimkasta]

Hey Richard

It s been a while I got my turntable rig back up and I started working on my phonocline and vsps again.

Quick question.
C3 value follows the normal coupling rules right? Calculating its value according to the input impedance of your preamp and the time constant / filter you want to use?
Oh and if my preamp is AC coupled, is it ok to omit C3 and R7?

 

[Mr Onion]

I have (literally) just replaced IC 2, 3 & 4 in my PC3 with LME49710's

Lower noise and clearer music are the first things to hit me.

... and thats 3 seconds into the first track. No brainer at the cost (~£8.00 )

 

[andykap]

I have (literally) just replaced IC 2, 3 & 4 in my PC3 with LME49710's

Lower noise and clearer music are the first things to hit me.

... and thats 3 seconds into the first track. No brainer at the cost (~£8.00 )

Why didn't you change IC1? I believe IC1 have more impact on the sound.
I use LT1028 in 1 and AD797 in 2. Very nice. I must try the LME49710 in 3 & 4 when I get home.