Solved!!
A 10nF cap from chassis to the ground of the SPDIF kills the noise.
Not bad for a result after about 4 years!!! Hey talking about SPDIF on the phonoclone thread - I know its OT, but there have been a couple of cases where people couldn't kill residual hum - this might be helpful to them.
A 10nF cap from chassis to the ground of the SPDIF kills the noise.
Not bad for a result after about 4 years!!! Hey talking about SPDIF on the phonoclone thread - I know its OT, but there have been a couple of cases where people couldn't kill residual hum - this might be helpful to them.
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Hi Fran, glad to hear it worked out. Weird that what is essentially an RF stopper (10 nF) affected what I would have thought was a ground loop (<200 Hz).
If it was your DAC though, I suppose there was the brute force solution available of simply unplugging it when you wanted to listen to a record.
In these cases, I wonder if the "standard" solution of putting 47ohms||100pF between COM and the chassis (earth) would solve things?
I can't try it myself, unfortunately, because I don't have any hum/noise in my system to prevent.
If it was your DAC though, I suppose there was the brute force solution available of simply unplugging it when you wanted to listen to a record.
In these cases, I wonder if the "standard" solution of putting 47ohms||100pF between COM and the chassis (earth) would solve things?
I can't try it myself, unfortunately, because I don't have any hum/noise in my system to prevent.
ahaja: correct - I normally use this to ground the shields of internal and external wires - and inerestingly enough, I did try this at the inputs of the phonoclone. It never made a damn bit of difference!!! But doing at the SPDIF output of the shiga... works a treat!! My phonoclone is a dual mono, with the Tx in a separate box which is earthed. But there is no connection from circuit gnd/COM to earth, my wiring is exactly as per the construction guide (the separate box with the 2 Tx is not shown).
I quickly drew the layout of the system in paint...on a laptop, with a shake!!
Fran
I quickly drew the layout of the system in paint...on a laptop, with a shake!!
Fran
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~60 hours of playing and things are getting better.
Highs and mid-highs have cleared a lot. Bass is still without body, a bit dry and not very dynamic. So are mid-lows making instruments sound thin.
The new mouser package arrived today.
The new toys are a new bigger case to fit the big toroids, an 182Q12 transformer (160VA), MUR860 diodes for the bridges and some nice neutrik XLR sockets.
So far I have modified the case to fit one of my 182P12 and the 182Q12. For now I only use the P, so that I can make direct evaluation of the changes step by step.
The first component change I tried was replacing the Vishay bridges with MUR860 diodes. The difference towards better sound was more than obvious.
Microsounds have filled the music which now feels multilayered rather than a sequence of sounds. Highs have more sustain. Room sounds and reflections have appeared again. And there is a very pleasant feeling on the music like it is blooming out of the speakers without effort.
The only issue now is the thin bass. Could this be because of the low Voltage on the op-amps? They are still running on 8.9V.
Highs and mid-highs have cleared a lot. Bass is still without body, a bit dry and not very dynamic. So are mid-lows making instruments sound thin.
The new mouser package arrived today.
The new toys are a new bigger case to fit the big toroids, an 182Q12 transformer (160VA), MUR860 diodes for the bridges and some nice neutrik XLR sockets.
So far I have modified the case to fit one of my 182P12 and the 182Q12. For now I only use the P, so that I can make direct evaluation of the changes step by step.
The first component change I tried was replacing the Vishay bridges with MUR860 diodes. The difference towards better sound was more than obvious.
Microsounds have filled the music which now feels multilayered rather than a sequence of sounds. Highs have more sustain. Room sounds and reflections have appeared again. And there is a very pleasant feeling on the music like it is blooming out of the speakers without effort.
The only issue now is the thin bass. Could this be because of the low Voltage on the op-amps? They are still running on 8.9V.
I wanted to experiment with alternative power supplies - something I've never done with the phonoclone before. I have one of the earlier phonoclone boards, without the bypass. Where is a good place to hook in the alternative supply? I would prefer to not have to cut traces etc if it could be avoided....
Fran
Fran
How i would do it.....
Remove the op amps of the X-reg part. Remove R9, R10, R19, R20 also remove both transistors. Connect your new + (positive voltage) to the 'E' pad of Q1 and your new - (negative voltage) to the 'E' pad of Q2 and the new '0' to COM.
Ronald.
Ronald's answer is absolutely correct. The problem though is this is essentially a one-way mod, since pulling out transistors and other X-reg components isn't something you can do repeatedly.
What I suggest instead is a second set of boards. Swapping boards in and out is relatively easy, and an X-reg-less phonoclone BOM cost is low.
I think R11-R14 but if you download this file you can calculate wich resistors you need to change to wich value. X-reg worksheet
Ronald.
Hmmm... the X-Reg excel sheet requires a headroom of 3V, while the one in the BOM requires 3.3V.
How critical is this?
I am asking because it can make a difference on how easily a proper resistor can be found.
For 3V headroom I can use a 25K for example coming to exactly 10V as per the calculator. While on the 3.3V, I have to go up at about 25K8 which will give 9.7V and is quite more difficult to find.
How critical is this?
I am asking because it can make a difference on how easily a proper resistor can be found.
For 3V headroom I can use a 25K for example coming to exactly 10V as per the calculator. While on the 3.3V, I have to go up at about 25K8 which will give 9.7V and is quite more difficult to find.
I went back and replaced the no-name generic bridges in my dual mono phonoclone3 with some fairchild stealth diodes. The ones I used were the R460PF2 type, 4A, 600V. These offer even higher specs than the oft recommended MUR860 (I thought I had some of these, but they were actually MSR860, and it was just a toss of a coin at that point).
Sound is a little more resolved, bass is a little deeper and tighter, but not that huge a difference. Glad I did it, not taking them back out - but the output cap would have a much bigger influence on the sound I think.
I might go back and fit some panasonic FC in the x-reg now. Its a pity that its hard to swap out the PS... truth be told, I'm probably not going to go do that.
RJM - I still have your BE boards here - would it be easier to do some power supply experiments on that?
Fran
Sound is a little more resolved, bass is a little deeper and tighter, but not that huge a difference. Glad I did it, not taking them back out - but the output cap would have a much bigger influence on the sound I think.
I might go back and fit some panasonic FC in the x-reg now. Its a pity that its hard to swap out the PS... truth be told, I'm probably not going to go do that.
RJM - I still have your BE boards here - would it be easier to do some power supply experiments on that?
Fran
MUR860s are 600V 8A.
The panasonics are in my to-try list as well. Probably the new FRs though. Maybe the Nichicon HEs too or Silmic II. Re-capping the board for testing is a problem though... We ll see...
But I am going to let the BOM Nichicons in for at least a month more before making any final conclusions about them.
My big problem is the hauntingly deep and sweet sound I got from the Lelons (yes those with the problematic electrolyte)...
I m also receiving the Mundorf Supremes tomorrow, so more play time is coming
The panasonics are in my to-try list as well. Probably the new FRs though. Maybe the Nichicon HEs too or Silmic II. Re-capping the board for testing is a problem though... We ll see...
But I am going to let the BOM Nichicons in for at least a month more before making any final conclusions about them.
My big problem is the hauntingly deep and sweet sound I got from the Lelons (yes those with the problematic electrolyte)...
I m also receiving the Mundorf Supremes tomorrow, so more play time is coming