Hi Richard, i am pleased to report that using the new grounding scheme has worked a treat the hum is fixed.
I have learned a few things- it must be use with shielded interconnect, keep the PC3 away from any nearby transformer otherwise it will hum like crazy.
Once again thank you for your help Richard.
I have learned a few things- it must be use with shielded interconnect, keep the PC3 away from any nearby transformer otherwise it will hum like crazy.
Once again thank you for your help Richard.
Finally, after spending its teenage years in storage, my PhonoClone RC Limited has been installed in a temporary chassis. This being my first venture into MC, I thought that I would test the RIAA with the already mounted MM Ortofon OM 10 Cartridge, just to see if anything would object. The result is as espected, low fidelity, but what has me concerned is the very low audio level. The phonoclone is hooked up to a GainClone and then a pair of Jordan JX92s. Not a powerful system, but still the output from this RIAA and with the high (4mV) output MM cartridge is very low.
I would have expected the opposite, a very distorted and loud output. Are my expectations plain wrong, or should I hold out with the purchase of a Denon DL-103 until after my inevitable mistakes have been rectified?
Hope you can help!
I would have expected the opposite, a very distorted and loud output. Are my expectations plain wrong, or should I hold out with the purchase of a Denon DL-103 until after my inevitable mistakes have been rectified?
Hope you can help!
Your phonoclone is working just fine, the problem is your testing method. The phonoclone circuit does not work with MM cartridges. Not at all. The gain will be too low even for the higher output signal, and the frequency response will not be correct. Remember the impedance of the cartridge is a vital parameter in the operating point of the phonoclone circuit, setting the gain of the first stage as R2/Zcart.
Last edited:
Another DL-103 + PhonoClone is born, in this case spun by a Pro-Ject Xpression MkII. After initial problems, with a loud hum resulting from improper isolation of the input RCA from the chassis, the analog voice of Tom Waits is now more haunting than ever. This being my first MC adventure I have nothing relevant to hold either component up against, perhaps only a temporary ignorance, but sofar a blissful of the kind so I am very satisfied. Thank you for putting this kit together RJM!
@Jezza56
Click the "ratsnest" button to fill the polygon shapes used to define the ground plane. In Eagle you can draw traces as lines and as shapes. The shapes are shown as dotted outlines when you first load the .brd file.
@dezzz
Thanks for posting. It's nice to hear from people who don't have problems once in a while! Posting photos to the Phonoclone thread is also encouraged.
Click the "ratsnest" button to fill the polygon shapes used to define the ground plane. In Eagle you can draw traces as lines and as shapes. The shapes are shown as dotted outlines when you first load the .brd file.
@dezzz
Thanks for posting. It's nice to hear from people who don't have problems once in a while! Posting photos to the Phonoclone thread is also encouraged.
I've just finished building this design and using +9V -9V from batteries.
I have had initial problems achieving the correct gain setting on the input stage, but this is almost resolved, barring a little bit of tweaking perhaps. I have a Linn Troika working nicely withb it, which in itself is quite an achievement due to the low output voltage of 0.2mV and low cartridge impedance of about 3.5 ohms.
The typical solution for a Troika is to use a 10:1 step-up transformer before a "normal" MC phono stage.
R2 is currently set at 100 ohms and is quite stable. I am very surprised about the sound. Detailed, but very assured.
The reason I had initial problems, because I read that most users would be Ok using 1.5K. I realise now that this value is critical, also experimented succesfully by increasing R6 marginally to add a tad more weight to the bass.
MY kEF 107s sounded a little bright when using 670 + 47k values. Closer to 750k appears to be a better balance. I know this is not true RIAA, but Kef 107s extend the bass response using the Kef Kube. I am finding that I have a nice balance now without using the Kube ( always been sceptical of the benefits of the Kube )
I initially used a 1.5K value for R2, because I was mistakingly looking at a specification for a Troika and approximating based on the recommended output impedance, duh ! I immediately realised my calculations were considerably out, when hearing huge amounts of volume with my valve amplifier at a low level.
The opamps are dual type BB OPA2134. I bought them for 1.85 + VAT from CPC. All the other parts I had were found from parts bins where I work. I am using an old hard disk caddy for a Seagate disk which was used for our old Sun servers, it has the IEC power connector and switch, just had to remove the insides, a very short mains cable attaches the 9V supplies, so they're external to make for easy charging. A little crude, but for me it is mainly about the music, and this phono stage has saved me a fortune, and the Troika is singing much to my amazement.
So , would like to say a big thank you to RJM and how much your effort is appreciated.
With the Troika being such a low output , I may need to increase the gain a little until I'm getting a more normal sensitivity for my amplifier ( volume control needs to be beyond 12 o'clock )
I think 150 ohm for R2 may be ample. Will definately have to think about a gain switch if using my Dynavetor DV-20X.
I have had initial problems achieving the correct gain setting on the input stage, but this is almost resolved, barring a little bit of tweaking perhaps. I have a Linn Troika working nicely withb it, which in itself is quite an achievement due to the low output voltage of 0.2mV and low cartridge impedance of about 3.5 ohms.
The typical solution for a Troika is to use a 10:1 step-up transformer before a "normal" MC phono stage.
R2 is currently set at 100 ohms and is quite stable. I am very surprised about the sound. Detailed, but very assured.
The reason I had initial problems, because I read that most users would be Ok using 1.5K. I realise now that this value is critical, also experimented succesfully by increasing R6 marginally to add a tad more weight to the bass.
MY kEF 107s sounded a little bright when using 670 + 47k values. Closer to 750k appears to be a better balance. I know this is not true RIAA, but Kef 107s extend the bass response using the Kef Kube. I am finding that I have a nice balance now without using the Kube ( always been sceptical of the benefits of the Kube )
I initially used a 1.5K value for R2, because I was mistakingly looking at a specification for a Troika and approximating based on the recommended output impedance, duh ! I immediately realised my calculations were considerably out, when hearing huge amounts of volume with my valve amplifier at a low level.
The opamps are dual type BB OPA2134. I bought them for 1.85 + VAT from CPC. All the other parts I had were found from parts bins where I work. I am using an old hard disk caddy for a Seagate disk which was used for our old Sun servers, it has the IEC power connector and switch, just had to remove the insides, a very short mains cable attaches the 9V supplies, so they're external to make for easy charging. A little crude, but for me it is mainly about the music, and this phono stage has saved me a fortune, and the Troika is singing much to my amazement.
So , would like to say a big thank you to RJM and how much your effort is appreciated.
With the Troika being such a low output , I may need to increase the gain a little until I'm getting a more normal sensitivity for my amplifier ( volume control needs to be beyond 12 o'clock )
I think 150 ohm for R2 may be ample. Will definately have to think about a gain switch if using my Dynavetor DV-20X.
Did you build a phonoclone or a VSPS? I honestly can't figure out which circuit it is you are talking about.
Phonoclone: R2 should be 150 ohms as per the Phonoclone Gain Calculator for 3.5 ohms and 0.2 mV. R6 is 168k ohms as per the BOM. OPA2134 are not ideal but will work.
VSPS: R2 should (coincidentally) also be about 100-150 ohms, but you are
pushing the op amp and performance will suffer as the feedback ratio decreases. The output signal will still be still rather low. R6 is ideally 732k or 750k, though in either circuit the value can be increased slightly to boost the bass response.
/R
Phonoclone: R2 should be 150 ohms as per the Phonoclone Gain Calculator for 3.5 ohms and 0.2 mV. R6 is 168k ohms as per the BOM. OPA2134 are not ideal but will work.
VSPS: R2 should (coincidentally) also be about 100-150 ohms, but you are
pushing the op amp and performance will suffer as the feedback ratio decreases. The output signal will still be still rather low. R6 is ideally 732k or 750k, though in either circuit the value can be increased slightly to boost the bass response.
/R
Actually, I'll go back to the OP27 and give it some listening time. I can't say there was such a major difference that it could ever be proven or not attributable to factors related to the mood I was in. I feel a blind test coming on ...
I often do this if ever I get the urge to start tweaking. It's happened to me on a number of occasions in the past, I convince myself when listening and trusting to my ears, that one component is better than another, but blind testing has a tendency to bring me back to down to earth.
I am of the opinion that the design can be more important than the component choice.
I know it's a little sad, but I tried a simple little experiment to see if I could hear the audible characteristic of the decoupling capacitor C3.
I installed a DIP switch that switched between a paper in oil cap and an electrolytic, I also did a similar test between the electrolytic and completely bypassed altogether ( shorted )
I did the test alone initially , and trusted my subjective opinion. Every time without question, I preferred the component bypassed, next the paper in oil, then the electrolytic.
Then I repeated the test blind, but got my wife to control which capacitors were in circuit. The results were inconclusive for me, when blind testing. In other words, I couldn't hear any degradation between the electrolytic and a shorting link.
I often do this if ever I get the urge to start tweaking. It's happened to me on a number of occasions in the past, I convince myself when listening and trusting to my ears, that one component is better than another, but blind testing has a tendency to bring me back to down to earth.
I am of the opinion that the design can be more important than the component choice.
I know it's a little sad, but I tried a simple little experiment to see if I could hear the audible characteristic of the decoupling capacitor C3.
I installed a DIP switch that switched between a paper in oil cap and an electrolytic, I also did a similar test between the electrolytic and completely bypassed altogether ( shorted )
I did the test alone initially , and trusted my subjective opinion. Every time without question, I preferred the component bypassed, next the paper in oil, then the electrolytic.
Then I repeated the test blind, but got my wife to control which capacitors were in circuit. The results were inconclusive for me, when blind testing. In other words, I couldn't hear any degradation between the electrolytic and a shorting link.
Phonoclone. Okay - in that case R6 should be about 768k. R2 should be about 150 ohms.
The 9V batteries will colour the sound. And of course the op amps and coupling capacitors.
I am in agreement with you on the tweaking aspect: Apart from the battery vs. active power supply, I doubt I could pick out component changes in a blind test even though I might hear the difference otherwise. No shame in preferring the OPA(2)134 - the noise floor is 6 dB higher than the OPA27, but it's a nice sounding op amp nonetheless. I would have used the single package OPA134 though. How did you configure the dual op amps : one per channel or one shared for the input stage, one shared for the output?
The 9V batteries will colour the sound. And of course the op amps and coupling capacitors.
I am in agreement with you on the tweaking aspect: Apart from the battery vs. active power supply, I doubt I could pick out component changes in a blind test even though I might hear the difference otherwise. No shame in preferring the OPA(2)134 - the noise floor is 6 dB higher than the OPA27, but it's a nice sounding op amp nonetheless. I would have used the single package OPA134 though. How did you configure the dual op amps : one per channel or one shared for the input stage, one shared for the output?
Last edited:
Thanks a lot for that RJM.
I had settled on more or less those values as they sounded about right.
I used one opamp for left channel and one for right channel. The 9V supplies are temporary, but to improve noise performance I'm using Elna 2000uf electrolytics for smoothing, bypassed with 2uF polypropylene cap and ceramic 10nF close to the opamp pins. I was influenced by the battery driven phono stage here:
http://www.fortunecity.com/rivendell/xentar/1179/projects/aaphono/aaphono.html
I wanted to make sure the design worked for me before splashing some cash on power supplies ( Troika is very low output and I had heard that I would need output transformer ), but I understand exactly what you're saying about the importance of the power supply.
However I will give a couple of 12V Yuasa batteries a try next ( I can get a couple of these for free) as I have had good experience with these on a few other projects.
I live in an area where the mains voltage is noisy, so batteries can prove a good alternative to noisy mains.
I use an isolation transformer for my 805 valve amp, and it improves things a lot.
My amp is Mingda Meixing, MC-805-AA. It only has 2 inputs, CD and Aux
I'm thinking to eliminate the Alps blue potentiometer in the amp ( which is a little noisy anyway ) by installing Alps Black Beauty potentiometers for the L and R channel directly in the Phono stage.
I bought a batch of these as I think they are one of the best potentiometers around, I have 10 of them sitting on my shelf doing nothing.
My thinking is that wiring the Alps Black beauty pot in the phono stage will effectively eliminate R7 and R8, and I can solder the interconnect cable directly to the input decoupling cap in the valve input stage , so C3 can be eliminated too.
I'm really pleased with the sound of this phono stage, my brother who is also a Linn owner, could not believe that the piece of matrix board with a few hard wired components connected next to my Linn was producing such a good sound. Less can often mean more in audio reproduction.
A little unrelated, but have a look at this design for this CD output stage , basically consists of 1 J-FET transistor and it works superb. I've used it in my Sony SCD-1.
Fet-ishizator
For me this phono stage is kind of in the same mould as this simple J-FET, simple but effective. My Linn K9 sounds good with it, the Dynavector DV-20X sounds very good, the Linn Troika sounds great, the better the cartridge the more you appreciate.
Thanks again.
I had settled on more or less those values as they sounded about right.
I used one opamp for left channel and one for right channel. The 9V supplies are temporary, but to improve noise performance I'm using Elna 2000uf electrolytics for smoothing, bypassed with 2uF polypropylene cap and ceramic 10nF close to the opamp pins. I was influenced by the battery driven phono stage here:
http://www.fortunecity.com/rivendell/xentar/1179/projects/aaphono/aaphono.html
I wanted to make sure the design worked for me before splashing some cash on power supplies ( Troika is very low output and I had heard that I would need output transformer ), but I understand exactly what you're saying about the importance of the power supply.
However I will give a couple of 12V Yuasa batteries a try next ( I can get a couple of these for free) as I have had good experience with these on a few other projects.
I live in an area where the mains voltage is noisy, so batteries can prove a good alternative to noisy mains.
I use an isolation transformer for my 805 valve amp, and it improves things a lot.
My amp is Mingda Meixing, MC-805-AA. It only has 2 inputs, CD and Aux
I'm thinking to eliminate the Alps blue potentiometer in the amp ( which is a little noisy anyway ) by installing Alps Black Beauty potentiometers for the L and R channel directly in the Phono stage.
I bought a batch of these as I think they are one of the best potentiometers around, I have 10 of them sitting on my shelf doing nothing.
My thinking is that wiring the Alps Black beauty pot in the phono stage will effectively eliminate R7 and R8, and I can solder the interconnect cable directly to the input decoupling cap in the valve input stage , so C3 can be eliminated too.
I'm really pleased with the sound of this phono stage, my brother who is also a Linn owner, could not believe that the piece of matrix board with a few hard wired components connected next to my Linn was producing such a good sound. Less can often mean more in audio reproduction.
A little unrelated, but have a look at this design for this CD output stage , basically consists of 1 J-FET transistor and it works superb. I've used it in my Sony SCD-1.
Fet-ishizator
For me this phono stage is kind of in the same mould as this simple J-FET, simple but effective. My Linn K9 sounds good with it, the Dynavector DV-20X sounds very good, the Linn Troika sounds great, the better the cartridge the more you appreciate.
Thanks again.
Would it not be better to keep the phonoclone running from 12v lead-acid on a permanent basis?
I can only think that if it is given pure 12V DC (Clean Power and as much as it needs) that it won't get any better than this.
Please correct me if my thinking is wrong, I am not terribly experienced in the land of bodging.
Ray
Different battery-based power supplies sound different. Different linear regulated supplies sound different. Overall, though, as a general rule, well-designed linear regulated supplies sound better than batteries.
Myself and many others have made the comparison and come to the this conclusion.
Myself and many others have made the comparison and come to the this conclusion.
