@devinyl
The Dynavector 10x5 output is 2.5 mV. It would normally pair with a 36-40 dB MM phono stage just fine, that you are finding that 50 dB (1 V nominal sensitivity!) is insufficient suggests a deeper problem that just the preamp.
To be clear: the VSPS300 at 50 dB with the 10x5 should be nearly as loud as a full line-level output, from a CD player for example.
@djnubz
link does not work. Suggest building a power supply according to the recommended BOM, and then experimenting afterwards. Dual mono: if you have $3000+ worth of components up and downstream, you should give it a try. If you don't, you don't need to worry over it.
The Dynavector 10x5 output is 2.5 mV. It would normally pair with a 36-40 dB MM phono stage just fine, that you are finding that 50 dB (1 V nominal sensitivity!) is insufficient suggests a deeper problem that just the preamp.
To be clear: the VSPS300 at 50 dB with the 10x5 should be nearly as loud as a full line-level output, from a CD player for example.
@djnubz
link does not work. Suggest building a power supply according to the recommended BOM, and then experimenting afterwards. Dual mono: if you have $3000+ worth of components up and downstream, you should give it a try. If you don't, you don't need to worry over it.
Cheers RJM. Looks like I've got to get the meter out and start looking for more of my mistakes as the vsps is nowhere near as loud as my CD line. Good / balanced sound from both channels, no distortion or interference, just not enough output. I noticed in one of dimkasta's earlier threads about low output due to low voltage from the x-regulator and looking for 10v to bump performance. I'll double check my R values against the BOM but whatever it is, its common to both boards. At least I'm consistent with my errors!
Here is another link
I just ordered 2 antek torroids and will be building a dual mono but I am curious what you think about using a high quality modern smps with your preamp design. I would think that a modern smps could work quite well due to their very low output impedance and ultrasonic switching frequencies.
I just ordered 2 antek torroids and will be building a dual mono but I am curious what you think about using a high quality modern smps with your preamp design. I would think that a modern smps could work quite well due to their very low output impedance and ultrasonic switching frequencies.
Accidentally switching components, 47 ohms for 47k ohms for example, could cause the loss of output signal. That seems more likely than a problem with the power rails.
I have no comment re. smps since I have never used them, or rather what I have used in various scenarios (not phono stages) invariably sounded awful, with the single exception of my Onkyo sound card.
I have no comment re. smps since I have never used them, or rather what I have used in various scenarios (not phono stages) invariably sounded awful, with the single exception of my Onkyo sound card.
Sorry for the late reply.. its vacation time, here at RJM Audio.
It looks fine from here. A good clue is whether you hear any change in the background noise when you power up the VSPS. If yes, then its probably working but you haven't connected the inputs to the cartridge properly. If no, its most likely a problem with the output connections.
Also, double check the voltage from IC1 pin 4 (-12 V) and pin 8 (+12 V) to GND.
It looks fine from here. A good clue is whether you hear any change in the background noise when you power up the VSPS. If yes, then its probably working but you haven't connected the inputs to the cartridge properly. If no, its most likely a problem with the output connections.
Also, double check the voltage from IC1 pin 4 (-12 V) and pin 8 (+12 V) to GND.
Clearly the voltage regulators are not operating properly. Could be a short from v+ to ground, or could be that the regs are shot. Do they get hot?
I would remove the opp amp from the socket and check the voltages at pin 4 and 8 again.
My best guess is you switched the lm7812 for the lm7912, so you have the negative reg on the positive rail.
I would remove the opp amp from the socket and check the voltages at pin 4 and 8 again.
My best guess is you switched the lm7812 for the lm7912, so you have the negative reg on the positive rail.
A DAC of the Klones!
I read with interest your article about the small DAC because it looks like something I could try to build without investing a whole lot of money in it. I thought this would make a good DAC for computer disc drive conversion to CD player.
At the end of the article you show a PCB for the project intended for through hole components. What are the dimensions of this board?
Also, specific recommendations for components are missing in some cases. Is there more information available some place?
I realize this is old stuff and probably isn't very interesting to most people any more but any help would be appreciated.
Thanks,
Roger
I read with interest your article about the small DAC because it looks like something I could try to build without investing a whole lot of money in it. I thought this would make a good DAC for computer disc drive conversion to CD player.
At the end of the article you show a PCB for the project intended for through hole components. What are the dimensions of this board?
Also, specific recommendations for components are missing in some cases. Is there more information available some place?
I realize this is old stuff and probably isn't very interesting to most people any more but any help would be appreciated.
Thanks,
Roger
Just wanted to ping back that the VSPS300 volume output issue is all resolved with nice listening levels at around 1/4 volume from my Dynavector 10x5 (set with 50db output). The boards have settled down very nicely with an amazingly detailed sound and shockingly deep bass that I've never encountered with any of my previous analogue setups.
Couldn't say a bigger thank you for such a nice build and for sharing it with the DIY community as I'm sure my system has never sounded this good. Now for some more undiscovered treasures amongst my old unplayed records.....
Couldn't say a bigger thank you for such a nice build and for sharing it with the DIY community as I'm sure my system has never sounded this good. Now for some more undiscovered treasures amongst my old unplayed records.....
I suddenly needed a phono stage and had begun some time ago to breadboard a VSPS, so after posting yesterday I decided to resurrect this beast and try it out. Finished it pretty quickly this morning and tested it out. Wow, I'm impressed! Good clarity and tone, fast, tight bass (though may be slightly overdone). That's using about 18v +/- battery supply and OPA2137. Wiring is quite, er, ratty. Didn't have any 2.2uF caps on hand so I'm temporarily using 2x 4.7uF caps in series (I think it measures about 2.3uF). I know the PS puts it at the limit of the PS voltage, but it's a junker opamp, so I'm willing to try it for a while.
I have a few questions, though. One is that there appears to be some distortion somewhere in the midrange or low-to-midrange (sounds somewhat like a rattle but my system has never rattled like that before). I have gain set a little above 40dB (using 500R for R2 instead of 680R) in part b/c I was using it with a Denon DL-110 which only puts out 1.5mV or so, pretty low for HOMC. Any idea what would cause that? The high voltage?
Also, there's a L/R channel imbalance. L side is louder and that's where I notice the distortion. Both R2 read pretty close so I don't think it's that.
Finally, anyone have any experience with OPA2137 and OPA2134 and running them at or above the max rating of 18v +/-? I may want to stick with 4x 9v batteries for now, and when new that'll bring the PS voltage up above +/-18v. I've considered sticking two LEDs in-line to drop the voltage a little and give me an "On" indicator, but I don't know what current draw VSPS has so don't know what that'll do to my battery life. I do have a 12v bi-polar PS that I will probably eventually use (and might bump to closer to 15v if my PS iron is willing).
Thanks for any input.
I have a few questions, though. One is that there appears to be some distortion somewhere in the midrange or low-to-midrange (sounds somewhat like a rattle but my system has never rattled like that before). I have gain set a little above 40dB (using 500R for R2 instead of 680R) in part b/c I was using it with a Denon DL-110 which only puts out 1.5mV or so, pretty low for HOMC. Any idea what would cause that? The high voltage?
Also, there's a L/R channel imbalance. L side is louder and that's where I notice the distortion. Both R2 read pretty close so I don't think it's that.
Finally, anyone have any experience with OPA2137 and OPA2134 and running them at or above the max rating of 18v +/-? I may want to stick with 4x 9v batteries for now, and when new that'll bring the PS voltage up above +/-18v. I've considered sticking two LEDs in-line to drop the voltage a little and give me an "On" indicator, but I don't know what current draw VSPS has so don't know what that'll do to my battery life. I do have a 12v bi-polar PS that I will probably eventually use (and might bump to closer to 15v if my PS iron is willing).
Thanks for any input.