The Phono Stage

Peter Daniel · 2012-01-17 10:35 pm

Send me an email for current price list.

freebee · 2012-01-18 6:27 am

The Phono Stage kit

Thanks Peter. I've just sent you an email via your Audio Sector website.

Peter Daniel · 2012-01-28 1:55 am

tms0425 said:
No change.

Here is what I did tonight:
- Removed both black phono board ground wires from black ground terminal and also separated them from each other (floated)
- Removed TT ground from isolated black ground terminal (floated)
- Removed AC power to the TT
- Removed AC filter board and input circuitry from the back right of chassis
- Hardwired AC directly to the 2 power supplies in front of the chassis. IEC is fed there to the front instead of the back right.
- Re-dressed all cables to ensure they are separated away from AC sources

There was no change at all from these steps. One channel slightly more hum than the other, but not much. Basically gain is fairly high, to the point where hiss is starting to be evident when the hum starts.

When I remove the input cables from the preamp or remove the headshell all is quiet, which I suppose makes sense. This old Empire tonearm cable and arm wiring does not have any shielding or a separate ground on it. The ground wire from the TT is tied to the plinth/chassis itself, a few inches from the arm base. I have a new TT and tonearm on the way so will replace that very soon.

I guess it's time to separate the power supplies from the phono boards, recheck soldering, and see what happens. It's just a pain because they're both hardwired.

The strange thing is I actually built up a PhonoClone3 without a case and I have a stock Jolida JD9 and neither of them hums with the same TT/arm.

I don't really have any particular advice here, as it seems like the problem is system dependent, however, this is what I observed today in my setup:

I've just built a preamp for a customer and was testing it before shipment. The unit was built exactly as pictured ion a first page of this thread. Chassis is grounded through the earth pin on a power entry module, RCA jacks are isolated from a chassis. I'm using Shelter 901 mounted on SME V tonearm.

There was initially low level hum at maximum volume level on a TVC based preamp. After ground wire from TT was connected to the chassis or one of the RCAs, the hum disappears.

tms0425 · 2012-01-28 2:46 am

Peter Daniel said:
I don't really have any particular advice here, as it seems like the problem is system dependent, however, this is what I observed today in my setup:

I've just built a preamp for a customer and was testing it before shipment. The unit was built exactly as pictured ion a first page of this thread. Chassis is grounded through the earth pin on a power entry module, RCA jacks are isolated from a chassis. I'm using Shelter 901 mounted on SME V tonearm.

There was initially low level hum at maximum volume level on a TVC based preamp. After ground wire from TT was connected to the chassis or one of the RCAs, the hum disappears.

Thanks Peter. I hope to get back to this problem this weekend. I tried to follow my usual common sense grounding rituals but there still seems to be a little special magic to get it all worked out sometimes. I have a whole new TT/tonearm setup now. It has a slate plinth so there isn't even a metal chassis to ground to other than the tonearm base and the bearing. I'll experiment a bit and see what happens. Hopefully it follows some logic this time ;-)

Tom

BigE · 2012-01-28 3:25 am

When I brought my phono stage to a frieds place, they hummed a bit. Making a better groung connection than an alligator clip solved the problem.

tms0425 · 2012-01-31 8:29 pm

I switched to the new TT and arm, and to a Zu Denon 103 instead of the 103R which has a lower resistance. Hum is significantly less now, even just using a nest of clipleads to experiment with. Hopefully I can get past it now. Thanks for help.

Tom

eelind · 2012-02-21 5:41 am

Hi Peter. Nice job. When thé LM3875 Will be finished, I think I Will Troy your phono stage. One question: did you think about using an RLC RIAA corrector instead of the R and C network?

Eric

Peter Daniel · 2012-02-23 5:25 pm

eelind said:
did you think about using an RLC RIAA corrector instead of the R and C network?

If something works good, I prefer not to touch it

eelind · 2012-02-25 7:18 am

I can imagine you don't want to change something that works really fine. But just for fun, if you had thé opportunity to try a LCR RIAA corrector, would you just put it in place of your RC network?

Peter Daniel · 2012-02-25 3:25 pm

I don't think its possible as the circuit uses pretty clever RC network that does work differently than the standard RC filtering and can't be replaced directly by LCR type.

MartinC700 · 2012-02-28 4:14 am

Peter, sent a couple of emails regarding availability of the PhonoStage, one via the email portal on this sitet, and one via the Audiosector website, but have recieved no reply. My email is a gmail account, perhaps it is being filtered at your end?

Regards

Martin

dimkasta · 2012-03-05 10:09 pm

Peter have you noticed any vibration on the 229D24?
I have mounted it without a pcb straight on an aluminum case and it vibrates like crazy...

Tarasque · 2012-03-06 11:21 am

Hi Peter

My phono is not working well. As soon as I inset teh opamps in the phono part the voltage on the supply drops and becomes asymitrical

How could I test the power section for correct operation?

Peter Daniel · 2012-03-06 9:44 pm

Your op amp is most likely damaged. Disconnect PS from the phono board and measure voltage on pads marked V+/V-/ GND

dimkasta said:
Peter have you noticed any vibration on the 229D24?
I have mounted it without a pcb straight on an aluminum case and it vibrates like crazy...

Yes, those transformers tend to vibrate a bit, especially on European voltage. Sometimes DC offset from the mains make them vibrate even more.

Szabcsi · 2012-03-27 11:06 pm

Hi,

About 2 months ago I bought a phono kit from Peter. He put together the phono section for me with Reference V-Caps and nude Vishays. Here is what I got: