Peter, figure 17 (current regulator) of the ST datasheet of LM337 provides a hint about C3 in Phono Stage
http://www.st.com/stonline/books/pdf/docs/2167.pdf
regards,
Jan
http://www.st.com/stonline/books/pdf/docs/2167.pdf
regards,
Jan
Finally....
I finally installed the V-caps in the board for “The Phono Stage”. I substituted a CuTF for the C2 cap (0.01uF), the C1 is a TFTF V-cap. I had to open up the volume control on the preamp almost all the way when listening. Preamp is a (Foreplay II with a Magnequest B7-15K output-transformer). Turntable is a home brew concoction (Rek-o-Kut string drive), with a Jelco 750-D tonearm and DL-103R cart. First listening impressions are very satisfying. The sound so far is a bit aggressive on occasion and full of energy in the highs. Bass is much better defined so far and not bloated. I’m going to let it burn in for a while with a CD player connected to a reverse RIAA filter and hopefully it will settle down a little. I’m actually quite impressed. I can hear the recording quality differences of LP’s quite easily at this early stage. This is my first solid state phono stage and I like it a lot. This phono will allow me to investigate more pricey carts, although I will most likely have to upgrade the rest of the system to match “The Phono Stage”. Hopefully I can figure out how to load a picture in the near future.
Cheers
Frank M
I finally installed the V-caps in the board for “The Phono Stage”. I substituted a CuTF for the C2 cap (0.01uF), the C1 is a TFTF V-cap. I had to open up the volume control on the preamp almost all the way when listening. Preamp is a (Foreplay II with a Magnequest B7-15K output-transformer). Turntable is a home brew concoction (Rek-o-Kut string drive), with a Jelco 750-D tonearm and DL-103R cart. First listening impressions are very satisfying. The sound so far is a bit aggressive on occasion and full of energy in the highs. Bass is much better defined so far and not bloated. I’m going to let it burn in for a while with a CD player connected to a reverse RIAA filter and hopefully it will settle down a little. I’m actually quite impressed. I can hear the recording quality differences of LP’s quite easily at this early stage. This is my first solid state phono stage and I like it a lot. This phono will allow me to investigate more pricey carts, although I will most likely have to upgrade the rest of the system to match “The Phono Stage”. Hopefully I can figure out how to load a picture in the near future.
Cheers
Frank M
I am hoping to complete mine tomorrow -- it is a dual mono version, and will be stuck into a 2x3 enclosure.
It will be playing a Denon 103D, and replacing a Denon HA-500 (Fully recapped) and the phono section of a Paragon system-e (via tape out) combination. The paragon has had some PS caps replaced, including the heater -- all mundorf.
Tomorrow is a big day. Hopefully, it all comes together.
It will be playing a Denon 103D, and replacing a Denon HA-500 (Fully recapped) and the phono section of a Paragon system-e (via tape out) combination. The paragon has had some PS caps replaced, including the heater -- all mundorf.
Tomorrow is a big day. Hopefully, it all comes together.
One of the power supplies got powered up today.
The initial voltages were +3.45 and -14.75.
Adding C3 brought the positive voltage up to +15.
Adding C4 brought the negative voltage down to -15.
Both of the regulators are ON semi. There is NO load at this time.
Will adding a load change the need for C3/C4? I will make the other channel without C3/C4, and see if there is need.
The initial voltages were +3.45 and -14.75.
Adding C3 brought the positive voltage up to +15.
Adding C4 brought the negative voltage down to -15.
Both of the regulators are ON semi. There is NO load at this time.
Will adding a load change the need for C3/C4? I will make the other channel without C3/C4, and see if there is need.
Attachments
I built the other channel, and added load. The positive voltage goes to 15.12, and the negative around -3 or -4 volts. Adding C4 and both voltages are the same. Removing C3 from the original channel and adding load has positive at 15.3 negative at -15.12. Is that ok?
One of the dual monos is now working. DC leakage is below about 0.5 mv.
It's gain is significantly less than the existing phono section - the HA-500 gives 24 db. I'm not sure about the paragon, but it's a standard MM phono section using 12ax7a.
I forgot about grounding the table to the ground post, but do I really need to use this? The ground post is connected to the chassis, which is connected to safety ground via the PCB board.
There is a minor hum in that channel, but more than the original Denon HA-500 and Paragon System-E as phono.
It is supposed to be dead quiet, I must have done something wrong. Either that, or the linestage has noise -- the hum goes up as I turn the volume control.
I connected both input and output shields together, with solid wire (Vcap cutoff) and connected the center of that to the SG pin. Otherwise, I would have run out of wire -- I'm using 18 awg solid core OPOCC Legenburg hookup wire everywhere.
Also, the TT ground goes to safety ground via it's own 3 prong cord.
I use DIY balanced power, and there was a bit less hum on balanced as opposed to wall power.
From what I've heard, it will take some time to break in. It sounds ok, but will need more time to open up.
I shall complete the other channel tomorrow and start on the break-in period. Will report back as progress is made.
One of the dual monos is now working. DC leakage is below about 0.5 mv.
It's gain is significantly less than the existing phono section - the HA-500 gives 24 db. I'm not sure about the paragon, but it's a standard MM phono section using 12ax7a.
I forgot about grounding the table to the ground post, but do I really need to use this? The ground post is connected to the chassis, which is connected to safety ground via the PCB board.
There is a minor hum in that channel, but more than the original Denon HA-500 and Paragon System-E as phono.
It is supposed to be dead quiet, I must have done something wrong. Either that, or the linestage has noise -- the hum goes up as I turn the volume control.
I connected both input and output shields together, with solid wire (Vcap cutoff) and connected the center of that to the SG pin. Otherwise, I would have run out of wire -- I'm using 18 awg solid core OPOCC Legenburg hookup wire everywhere.
Also, the TT ground goes to safety ground via it's own 3 prong cord.
I use DIY balanced power, and there was a bit less hum on balanced as opposed to wall power.
From what I've heard, it will take some time to break in. It sounds ok, but will need more time to open up.
I shall complete the other channel tomorrow and start on the break-in period. Will report back as progress is made.
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Correction. The hum is only from one channel. The other channel is dead quiet.
Faulty transformer perhaps? I broke a wire and repaired it by soldering a strand of copper from a power cable to bridge the gap, and think it is this transformer that is humming.
I guess replacement of the transformer would be the best option. Dammit!
Faulty transformer perhaps? I broke a wire and repaired it by soldering a strand of copper from a power cable to bridge the gap, and think it is this transformer that is humming.
I guess replacement of the transformer would be the best option. Dammit!
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Did not need to replace. I replaced the signal wiring and did that grounding correctly. Twisting the 24 awg worked great! The unit is dead quiet.
I used 24 awg mundorf silver/gold. It's ok, smooth, has good tone, but the legenburg 18 gauge was more immediate sounding.
I'll try next week with legenburg 22 awg and twist hard!!!
Thanks for all the help Peter!
I used 24 awg mundorf silver/gold. It's ok, smooth, has good tone, but the legenburg 18 gauge was more immediate sounding.
I'll try next week with legenburg 22 awg and twist hard!!!
Thanks for all the help Peter!
When I first started using my Phono Stage, the sound was also really aggressive but extremely detailed. I didn't use V-Caps, but a mix of Rel-Cap teflons and polysterene.
As time went on, the aggressiveness disappeared and the sound has become very (at least to my ears) neutral. This is my favorite phono stage of all time - at least with the Denon DL-103R. I've been looking to upgrade my vinyl front end - better arm and cart, but I fully expect the Phono Stage to continue to be my reference.
As time went on, the aggressiveness disappeared and the sound has become very (at least to my ears) neutral. This is my favorite phono stage of all time - at least with the Denon DL-103R. I've been looking to upgrade my vinyl front end - better arm and cart, but I fully expect the Phono Stage to continue to be my reference.
I find a Denon 160 unlistenable with this phono stage.
With the Denon HA-500 and the Paragon System E, my old 103D sounds MUCH better, and the 160 becomes listenable.
But let's face it, the 103D is really nothing special, probably worn out, and the 160 is simply outclassed.
With a borrowed Benz ACE (pre S) it sounds *far* better, and not so special via HA-500 and Paragon.
There is one change I must do, as I have been informed that using the case ground for the TT ground wire is incorrect -- I should be using PS common for the TT ground wire.
A second change is warranted -- the signal wires used were 24 awg Mundorf Gold/Silver. 24 awg legenburg UPOCCC have just arrived.
In an earlier iteration, I had used 18 gauge UPOCCC copper, but did not twist as I did not have enough, and was having hum issues. However, the sound with the copper was superior than with the silver/gold signal wires -- I regretted the change since I made it.
There are MANY hours on that wire, as I was hoping beyond hope that it would begin to sound better, but alas, no mystical forces materialzed, and it sounds the same as it did once the wires were swapped. As they were twisted, the phono section got quieter, but it's still not up to it's potential.
I'll report back once the silver/gold wire is removed. Yes, I dislike that wire so much. It totally killed the life in the music -- or perhaps it revealed the horrorshow of a cartridge that is hooked up to it, as the Benz ACE sounded good.
This phono section is extremely revealing, which is why I like it. Too bad, I only have the 103D on hand to voice it.
With the Denon HA-500 and the Paragon System E, my old 103D sounds MUCH better, and the 160 becomes listenable.
But let's face it, the 103D is really nothing special, probably worn out, and the 160 is simply outclassed.
With a borrowed Benz ACE (pre S) it sounds *far* better, and not so special via HA-500 and Paragon.
There is one change I must do, as I have been informed that using the case ground for the TT ground wire is incorrect -- I should be using PS common for the TT ground wire.
A second change is warranted -- the signal wires used were 24 awg Mundorf Gold/Silver. 24 awg legenburg UPOCCC have just arrived.
In an earlier iteration, I had used 18 gauge UPOCCC copper, but did not twist as I did not have enough, and was having hum issues. However, the sound with the copper was superior than with the silver/gold signal wires -- I regretted the change since I made it.
There are MANY hours on that wire, as I was hoping beyond hope that it would begin to sound better, but alas, no mystical forces materialzed, and it sounds the same as it did once the wires were swapped. As they were twisted, the phono section got quieter, but it's still not up to it's potential.
I'll report back once the silver/gold wire is removed. Yes, I dislike that wire so much. It totally killed the life in the music -- or perhaps it revealed the horrorshow of a cartridge that is hooked up to it, as the Benz ACE sounded good.
This phono section is extremely revealing, which is why I like it. Too bad, I only have the 103D on hand to voice it.
BTW, all the critical voicing of this phono stage circuit was done in this particular system: New Page 2