First off, the frequency response of the VSPS doesn't rise at high frequency. It just stops falling. Normalized to the RIAA response however, it actual HF response exceeds the RIAA standard, so the response plot ticks upwards.
Several years back I revised the VSPS circuit to remove the "Allen Wright" 50 kHz time constant responsible for this leveling out of the HF response. The response is now flat to 20 kHz.
If you want to quick-and-dirty mod your VSPS, just short over (or replace with a wire) the resistor which is in series with C1. I think it was labelled R3 in the original version, and was nominally 2.2 kohms. If you want to go all the way to revise your VSPS to the current version, change the 105kohm resistor to 110k, and the 732kohm resistor to 768k.
Attachments
Update Jun 18th re. postal delivery
Finally, most major countries in Europe are back to normal service.
Parcels to United States is still suspended.
https://www.post.japanpost.jp/int/information/2020/0618_01_01_en.pdf
Finally, most major countries in Europe are back to normal service.
Parcels to United States is still suspended.
https://www.post.japanpost.jp/int/information/2020/0618_01_01_en.pdf
SERVICE ADVISORY
June 21th 2020
VSPS KIT
The last four VSPS Kits to be shipped out were sent with 100 ohms for R6/R6L instead of 100 kohms.
I'm pretty sure they are still in transit or just arrived. Andy got his and kindly notified me of the mistake. Thure, Jaap, and Michel are probably still in the post. I will be in email contact shortly.
Apologies for the screw-up
Richard
June 21th 2020
VSPS KIT
The last four VSPS Kits to be shipped out were sent with 100 ohms for R6/R6L instead of 100 kohms.
I'm pretty sure they are still in transit or just arrived. Andy got his and kindly notified me of the mistake. Thure, Jaap, and Michel are probably still in the post. I will be in email contact shortly.
Apologies for the screw-up
Richard
Richard,
I have now added a DIY EAR834P clone to my arsenal.
I am glad to notify that your circuit fares very well against it.
The VSPS is so similar to the sound I get from the tube phono corrector that it is hard to tell it's a solid state design.
And if I replace the LME49720HA I use right now with the original OPA2134 that you recommend plus those two Kamaya carbon composition output resistors the sound is even more tube-like. However, I still slightly prefer the metal can opamp for its clarity and dynamic character.
The only major change is a separate regulator supply board (LM317/337) to power the VSPS.
Also, I used Kiwame resistors in some positions and replaced the two ceramic capacitors near the opamp with Xicon polysterene ones.
Great little kit!
Thank you!
I have now added a DIY EAR834P clone to my arsenal.
I am glad to notify that your circuit fares very well against it.
The VSPS is so similar to the sound I get from the tube phono corrector that it is hard to tell it's a solid state design.
And if I replace the LME49720HA I use right now with the original OPA2134 that you recommend plus those two Kamaya carbon composition output resistors the sound is even more tube-like. However, I still slightly prefer the metal can opamp for its clarity and dynamic character.
The only major change is a separate regulator supply board (LM317/337) to power the VSPS.
Also, I used Kiwame resistors in some positions and replaced the two ceramic capacitors near the opamp with Xicon polysterene ones.
Great little kit!
Thank you!
Last edited:
Hi Richard and others.
You may remember my posts a few months back, I made a stereo VSPS in a single enclosure and had slight hum/buzzing issues. Well back then I eventually changed my in/out wiring to shielded cables. At first I thought it did the trick but when I plugged it into my main system (NAD amp with Planar 3 and Nag MP-110 cart) I noticed that while the left channel got considerably quieter, I still had hum in the right channel.
A bit frustrated with that and the fact that my small enclosure made my life difficult I ordered a new enclosure to separate the PS from the VSPS.
Last night I finished my 2 box build, everything looked as it should, but I still get hum in the right channel
I tried putting the boxes at different distances, moved them away from my amp, away from each other, etc, still get that noise on that one channel only.
Im a bit lost now, if I somehow made a ground loop, it would hum in both channels right? Maybe one of my RCAs ended up touching the case ?
I mostly needed to rant, if someone has ideas, im very open to them.
Cheers
You may remember my posts a few months back, I made a stereo VSPS in a single enclosure and had slight hum/buzzing issues. Well back then I eventually changed my in/out wiring to shielded cables. At first I thought it did the trick but when I plugged it into my main system (NAD amp with Planar 3 and Nag MP-110 cart) I noticed that while the left channel got considerably quieter, I still had hum in the right channel.
A bit frustrated with that and the fact that my small enclosure made my life difficult I ordered a new enclosure to separate the PS from the VSPS.
Last night I finished my 2 box build, everything looked as it should, but I still get hum in the right channel
I tried putting the boxes at different distances, moved them away from my amp, away from each other, etc, still get that noise on that one channel only. Im a bit lost now, if I somehow made a ground loop, it would hum in both channels right? Maybe one of my RCAs ended up touching the case ?
I mostly needed to rant, if someone has ideas, im very open to them.
Cheers
Oh after writing that I realized I didn't test this without my turntable. Well turns out the noise is gone when no turntable is connected. And then I figured I'd try reversing the turntable wires, the noise moved from right to left.
I could swear I made that test before the rebuild and the noise was constantly on the right channel back then, now Im doubting myself.
The Regas suposedly have their ground wire in one channel only, left I think, could this be causing me issues?
Thanks,
I could swear I made that test before the rebuild and the noise was constantly on the right channel back then, now Im doubting myself.
The Regas suposedly have their ground wire in one channel only, left I think, could this be causing me issues?
Thanks,
Who knows?
I suppose you will have to open it up and look inside.
But there is something else you could look into.
If your turntable has a metal headshell, try isolating the metal body of your cartridge from making any electrical contact with it.
It is worth trying it, because there are some cartridges that form a kind of ground loop when not isolated.
I suppose you will have to open it up and look inside.
But there is something else you could look into.
If your turntable has a metal headshell, try isolating the metal body of your cartridge from making any electrical contact with it.
It is worth trying it, because there are some cartridges that form a kind of ground loop when not isolated.
@cok666n
Sorry to hear you are having noise issues. From your description it is an issue with the grounding layout of the turntable and VSPS not being compatible.
The VSPS is not designed to carry the ground/com over the input signal return (IN-). Though I can't tell you exactly why, I can tell you the solution. What you need to do is take the IN- R and L from the RCA jacks and wire them back to GND on the VSPS, rather than the IN- L and IN- R pads. That should alleviate the problem, though I have no guarantee.
Sorry to hear you are having noise issues. From your description it is an issue with the grounding layout of the turntable and VSPS not being compatible.
The VSPS is not designed to carry the ground/com over the input signal return (IN-). Though I can't tell you exactly why, I can tell you the solution. What you need to do is take the IN- R and L from the RCA jacks and wire them back to GND on the VSPS, rather than the IN- L and IN- R pads. That should alleviate the problem, though I have no guarantee.
Hi Richard,
Thanks for the advice. I moved the IN- to GND. I didnt notice any improvement. Note that I didnt unplug the tt ground terminal thinking it could be handy and still have the GND linked to the case.
.
I felt a little silly doing that modification since the GND pad is millimeters away from the IN- pads I assumed they are quite the same connection point?
Did you mean the COM pad by any chance?
Evonimous brings good points, my tonearm is conductive and my cart seems to be in contact. I did change carts along this journey so it is possible that is now my issue and has nothing to do with the VSPS.
I'm going to give it a try on my second table very soon.
Thanks for the help, really appreciate it.
Thanks for the advice. I moved the IN- to GND. I didnt notice any improvement. Note that I didnt unplug the tt ground terminal thinking it could be handy and still have the GND linked to the case.
.
I felt a little silly doing that modification since the GND pad is millimeters away from the IN- pads I assumed they are quite the same connection point?
Did you mean the COM pad by any chance?
Evonimous brings good points, my tonearm is conductive and my cart seems to be in contact. I did change carts along this journey so it is possible that is now my issue and has nothing to do with the VSPS.
I'm going to give it a try on my second table very soon.
Thanks for the help, really appreciate it.
Hi cok666n
I’m not sure what tonearm you have on your Rega Planar, but I have a modified Rega rb250 as one of the arms on my table that I use with MM carts.
It developed a similar problem a few years back which I discovered after research was related to the grounding design of the arm which relied on the arm bearings conveying ground from the arm to the base. This grounding scheme was not working any more.
I ended up removing the counter weight and end stub from the arm and feeding a very fine single loosely coiled strand of silver tinned wire from the grounding lug in the base up through the wiring hole by the bearings.
I pulled the wire out the back of the stub mounting hole where I flattened its end with smooth jaw pliers and then jammed it in the threads while reinstalling the end stub.
Afterwards I tested for continuity between the base and arm and the problem was solved and has never returned.
It’s important to use very fine wire and to leave it loosely coiled inside so as to not interfere with the motion of the arm at all.
Perhaps you should test for continuity from the base through the arm if yours is of similar design.
I’m not sure what tonearm you have on your Rega Planar, but I have a modified Rega rb250 as one of the arms on my table that I use with MM carts.
It developed a similar problem a few years back which I discovered after research was related to the grounding design of the arm which relied on the arm bearings conveying ground from the arm to the base. This grounding scheme was not working any more.
I ended up removing the counter weight and end stub from the arm and feeding a very fine single loosely coiled strand of silver tinned wire from the grounding lug in the base up through the wiring hole by the bearings.
I pulled the wire out the back of the stub mounting hole where I flattened its end with smooth jaw pliers and then jammed it in the threads while reinstalling the end stub.
Afterwards I tested for continuity between the base and arm and the problem was solved and has never returned.
It’s important to use very fine wire and to leave it loosely coiled inside so as to not interfere with the motion of the arm at all.
Perhaps you should test for continuity from the base through the arm if yours is of similar design.
Intense IM distortion
Hello,
I just finally completed my RJM VSPS preamp, using a MUSES01 opamp, mostly AB resistors, V-cap ODAM blocking caps and Corning glass capacitors in the RIAA feedback. Unfortunately, there is intense “farty” distortion that I believe is IM distortion, since it is not apparent with simple test tones. I hear the same distortion both with vinyl and CD sources (the latter through an inverse RIAA filter/attenuators).
I should add that I am powering with +/-12V from a regulated Lambda power supply.
Any suggestions?
Thanks, Dint
Hello,
I just finally completed my RJM VSPS preamp, using a MUSES01 opamp, mostly AB resistors, V-cap ODAM blocking caps and Corning glass capacitors in the RIAA feedback. Unfortunately, there is intense “farty” distortion that I believe is IM distortion, since it is not apparent with simple test tones. I hear the same distortion both with vinyl and CD sources (the latter through an inverse RIAA filter/attenuators).
I should add that I am powering with +/-12V from a regulated Lambda power supply.
Any suggestions?
Thanks, Dint
Possible cause?
I forgot that I disregarded the construction guide by strapping the LR grounds at both the input and output. At the output I don’t have a choice, since my preamp (an exceptionally transparent Stereo Coffee LDR unit) combines LR grounds. However, I can and will split the input grounds as recommended. Is this likely to matter?
Thanks, Dint
I forgot that I disregarded the construction guide by strapping the LR grounds at both the input and output. At the output I don’t have a choice, since my preamp (an exceptionally transparent Stereo Coffee LDR unit) combines LR grounds. However, I can and will split the input grounds as recommended. Is this likely to matter?
Thanks, Dint
Whoops, Undervoltage!
I realized that I was feeding the VSPS too low a voltage. Embarrassing mistake! At 15V the gross distortion is gone. Still a little “Blatty” at low frequencies, particularly at low volumes, but working and listenable. Now I will optimize my new tonearm alignment and report back.
What is the maximum safe voltage? (16V sounds better than 15 but afraid to go higher).
Thanks, and sorry for my stupidity.
Dint
I realized that I was feeding the VSPS too low a voltage. Embarrassing mistake! At 15V the gross distortion is gone. Still a little “Blatty” at low frequencies, particularly at low volumes, but working and listenable. Now I will optimize my new tonearm alignment and report back.
What is the maximum safe voltage? (16V sounds better than 15 but afraid to go higher).
Thanks, and sorry for my stupidity.
Dint
Hi Dint!
If you have a 12 V regulated power supply, you can remove the LM7812/7912 regulators from the board and bypass them by putting a shorting wire to connect the pads marked with the little "U" symbols on the board. If you leave the regulators in, you need about 14-15 V on the V++ to power them properly.
Don't worry that your preamp combined grounds, all stereo components must at some point. Wire the VSPS as shown, with the chassis/TT connecting GND and IN- and out- going to the isolated rings of the RGA jacks.
If you have a 12 V regulated power supply, you can remove the LM7812/7912 regulators from the board and bypass them by putting a shorting wire to connect the pads marked with the little "U" symbols on the board. If you leave the regulators in, you need about 14-15 V on the V++ to power them properly.
Don't worry that your preamp combined grounds, all stereo components must at some point. Wire the VSPS as shown, with the chassis/TT connecting GND and IN- and out- going to the isolated rings of the RGA jacks.