The Phonoclone and VSPS PCB Help Desk

I'm using the Phonoclone BE with much joy and am happy with it. No particular problems. I know the saying "Don't fix if ...".

Having said that, I'm always looking for areas to improve. Noise could be a little lower, just as sensitivity to RF pickup. This is my current setup, built by the book with a 50VA trafo. Could I improve on the wiring, parts, the case of somewhere else based on experiences of newer iterations?

Ralph

An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
 
woodturner-fran said:
I'm sure RJM will step in here, but IIRC, I asked this and was told not to use any smoothing at the Tx, just bring the raw rectified DC to the phonoclone.
Not having build a phonoclone I cannot say if your interpretation will sound nicer, but this philosophy of bringing the rectified half waves (and the very short charging pulses) to remote smoothing caps brings all the pulse currents into the very sensitive areas of the circuitry.

I would at least try the compact TINY loop area method to prove it one way or the other.

I consider it very important to keep the transformer secondary and rectifier and first stage smoothing in a very tight loop area configuration and if possible to keep all the interconnections between these three PSU components short.
 

rjm

Member
Joined 2004
Paid Member
but this philosophy of bringing the rectified half waves (and the very short charging pulses) to remote smoothing caps brings all the pulse currents into the very sensitive areas of the circuitry.

This is true, but it also put all the resistance (and inductance) of the lead wire between the cap and the diode, which if it does anything improves the filtering and dampens the diode spike. It avoids having, from the point of view of the op-amp, a capacitor sitting a long way from the power pins behind a significant inductance. Anyway trust me it sounds much better without capacitors in the power supply box itself. But you are welcome to do the test yourself.

Richard
 
Filtering

Hello.
A few months ago I build my last version of Phonoclone I use till now. This is total dual mono. Each opamp on the pre pcb has each own regulators (lm317/337). Second opamp is biased to class A by adding a 2k resistor (supply is 2x15V). Filtering: 70 000uF/25V & 8 inductors 10mH/1A for each channel. I bypassed also schottky (1N5819 1A/40V) in rect by a small cap.

http://img170.imageshack.us/my.php?image=phonoclonee002fs8.jpg

Chassis .... I called it The Tower :)...why .... see the pictures:
1. http://img502.imageshack.us/my.php?image=thetower002xp4.jpg
2. http://img517.imageshack.us/my.php?image=thetower003zu9.jpg

Sound for me and friends who listened that version is wonderfull. Bigger, deeper bas, incredible soundstage. High freq are also beatiful. This isn't cheap improovement but I can recommend it for everyone.

Krzysztof
 
Re: Filtering

ahaja said:
Hello.
A few months ago I build my last version of Phonoclone I use till now. This is total dual mono. Each opamp on the pre pcb has each own regulators (lm317/337). Second opamp is biased to class A by adding a 2k resistor (supply is 2x15V). Filtering: 70 000uF/25V & 8 inductors 10mH/1A for each channel. I bypassed also schottky (1N5819 1A/40V) in rect by a small cap.

http://img170.imageshack.us/my.php?image=phonoclonee002fs8.jpg

Chassis .... I called it The Tower :)...why .... see the pictures:
1. http://img502.imageshack.us/my.php?image=thetower002xp4.jpg
2. http://img517.imageshack.us/my.php?image=thetower003zu9.jpg

Sound for me and friends who listened that version is wonderfull. Bigger, deeper bas, incredible soundstage. High freq are also beatiful. This isn't cheap improovement but I can recommend it for everyone.

Krzysztof


Wow that's pretty impressive. I just started building mine today and it will be dual mono as well. I got one channel finished and it worked the first time, I can't wait to finish the other channel.
:)
 

rjm

Member
Joined 2004
Paid Member
No, there is no penalty for this since the Phonoclone can drive the pot directly even if it has a relatively low impedance, like 5k or less. The purpose of original gain/buffer stage before the pot would have been to present a very high impedance to the input source device, so as to be compatible with tube tuners and so forth incapable of driving low impedance loads.