Eagle home page
The program and documentation, libraries etc can be downloaded free from there.
I can provide help with the layouts. Just so long as I don't have to solder anything. While you've convinced me that working with SMT is possible, I don't yet feel any inclination to try it myself.
/R
The program and documentation, libraries etc can be downloaded free from there.
I can provide help with the layouts. Just so long as I don't have to solder anything. While you've convinced me that working with SMT is possible, I don't yet feel any inclination to try it myself.
/R
9.7 ohms is perfectly workable, I suggest starting with a feedback resistor of 680 ohms, giving 36 dB in the first stage.
A reminder that you can always convert a phonoclone back into a traditional input by adding a resistor in series with the cartridge equal to the recommended cartridge load. For cartridges with recommended loads below 100 ohms and an OP27 doing this will not add significantly to the output noise.
Richard
A reminder that you can always convert a phonoclone back into a traditional input by adding a resistor in series with the cartridge equal to the recommended cartridge load. For cartridges with recommended loads below 100 ohms and an OP27 doing this will not add significantly to the output noise.
Richard
Re: How similar to the PHONOCUBE is the PHONOCLONE?
As I recall it rjm did not actually open up a phonocube and copy the circuit, he just figured out how an active RIAA circuit would have to be if it was to have 9 components, and a zero impedance.
I have yet to see someone document an opening of the original PC or publishing a schematic of the circuit.
It is somewhat odd, because opening and examening the Phonocube is a breeze, compared to the gaincard where I believe you have to desolder the input cables to do it.
rickmcinnis said:
As I recall it rjm did not actually open up a phonocube and copy the circuit, he just figured out how an active RIAA circuit would have to be if it was to have 9 components, and a zero impedance.
I have yet to see someone document an opening of the original PC or publishing a schematic of the circuit.
It is somewhat odd, because opening and examening the Phonocube is a breeze, compared to the gaincard where I believe you have to desolder the input cables to do it.
Phonoclone & the Wright constant
Is there no need to incorporate Allen Wrights 75uS constant within the PHONOCLONE?
Or do you figure the moving coils natural (typical?) rise in the highest frequencies compensates for the unlimited 318 uS RIAA rolloff?
Also, are the feedback resistance values THAT high to make for small (in size) capacitors? Empirically, it would seem that smaller resistances might have some advantages.
Obviously, noise does not seem to be a problem with the PHONOCLONE! So, my curiousity is simply that. I guess I would rather use something other than the usual silver mica, I know there are some really good ones out there but they are not easily found. My first inclination is to use the RELCAP polystyrenes. Would you have any reservations about that?
Of course, I should build it and see for myself!
Is it settled that the OP-27 is the way to go? I promise I have read through the vast majority of posts and I think that is what I read but I am not sure.
THANKS VERY MUCH,
Is there no need to incorporate Allen Wrights 75uS constant within the PHONOCLONE?
Or do you figure the moving coils natural (typical?) rise in the highest frequencies compensates for the unlimited 318 uS RIAA rolloff?
Also, are the feedback resistance values THAT high to make for small (in size) capacitors? Empirically, it would seem that smaller resistances might have some advantages.
Obviously, noise does not seem to be a problem with the PHONOCLONE! So, my curiousity is simply that. I guess I would rather use something other than the usual silver mica, I know there are some really good ones out there but they are not easily found. My first inclination is to use the RELCAP polystyrenes. Would you have any reservations about that?
Of course, I should build it and see for myself!
Is it settled that the OP-27 is the way to go? I promise I have read through the vast majority of posts and I think that is what I read but I am not sure.
THANKS VERY MUCH,
Hi Rick,
concerning op-amps, here I made some comparisons. It's a highly subjective area, though.
I tried the 'allen wright' time constant with the clone, and it sounded weird, as if I got oscillations (tired and stressed sound). But the chip was cool and I did not check with a scope back then. I did not find it so helpful with other circuits, so i did not check further.
And if you have some half-speed mastered LP's, it's worse than without...
Rüdiger
concerning op-amps, here I made some comparisons. It's a highly subjective area, though.
I tried the 'allen wright' time constant with the clone, and it sounded weird, as if I got oscillations (tired and stressed sound). But the chip was cool and I did not check with a scope back then. I did not find it so helpful with other circuits, so i did not check further.
And if you have some half-speed mastered LP's, it's worse than without...
Rüdiger
Onvinyls' phonoclone
Thanks for directing me to the thread.
I admire your ambitiousness!
When you tried batteries: were they "large" capacity? What did you find lacking (if they were "large")?
Have you tried shunt regulators? I want to try the TENTLABS devices. Found his valve heater regulators to be excellent.
I guess I am skeptical of series pass element regulators. I know what they do to valve circuits and cannot see why they would not be as harmful to a transistor circuit.
I found many answers to my questions within the thread.
Has your circuit evolved from then? Are you still listening to it? Still using the DENON?
Out of curiosity, what turntable and arm are you using?
Thanks, again, for your help,
Thanks for directing me to the thread.
I admire your ambitiousness!
When you tried batteries: were they "large" capacity? What did you find lacking (if they were "large")?
Have you tried shunt regulators? I want to try the TENTLABS devices. Found his valve heater regulators to be excellent.
I guess I am skeptical of series pass element regulators. I know what they do to valve circuits and cannot see why they would not be as harmful to a transistor circuit.
I found many answers to my questions within the thread.
Has your circuit evolved from then? Are you still listening to it? Still using the DENON?
Out of curiosity, what turntable and arm are you using?
Thanks, again, for your help,
Re: Onvinyls' phonoclone
I also tried batteries, initially with Ono. I didn't want to go into building proper PS so I took a simple way out and connected Ono to 4 x 12V, 7.2 Ah Panasonic cells. The circuit sounded OK, but nothing spectacular and after a while I did not care listening to vinyl at all.
After that, I built phonocube clone, this time with IC regulators and the circuit sounded much better than Ono, so I was drawn into vinyl again. Just out of curiosity, I tried phonoclone with the same batteries I was using previosly with Ono (but still regulators and main filter caps in place) and again, I noticed similar difficiencies: rather harsh sound, lacking smoothness, a bit mechanical with no musical energy present.
I then run Ono with simple regulators and AC power supply, and the circuit sounded much better, to the point that I actually started to enjoy it a lot.
So no batteries for me with phonostages.
rickmcinnis said:
I also tried batteries, initially with Ono. I didn't want to go into building proper PS so I took a simple way out and connected Ono to 4 x 12V, 7.2 Ah Panasonic cells. The circuit sounded OK, but nothing spectacular and after a while I did not care listening to vinyl at all.
After that, I built phonocube clone, this time with IC regulators and the circuit sounded much better than Ono, so I was drawn into vinyl again. Just out of curiosity, I tried phonoclone with the same batteries I was using previosly with Ono (but still regulators and main filter caps in place) and again, I noticed similar difficiencies: rather harsh sound, lacking smoothness, a bit mechanical with no musical energy present.
I then run Ono with simple regulators and AC power supply, and the circuit sounded much better, to the point that I actually started to enjoy it a lot.
So no batteries for me with phonostages.
Attachments
Re: Phonoclone & the Wright constant
Like in the case of the Gaincard, there's not all that much you can do if you are to stick with the minimum number of components. The important characteristic of the Phonocube is that it's a current-source device.
Need? If you believe you can hear frequencies up to 50kHz, yes.
The fact that it's a current-source device might mean the 75uS constant is less relevant. MC carts have a frequency response up to 50k because of the low impedance. But since we are dealing with current, impedance is taken out of the equation. If there's a rise, the rise should be more prominent with the Phonoclone.
rickmcinnis said:
Like in the case of the Gaincard, there's not all that much you can do if you are to stick with the minimum number of components. The important characteristic of the Phonocube is that it's a current-source device.
rickmcinnis said:
Need? If you believe you can hear frequencies up to 50kHz, yes.
The fact that it's a current-source device might mean the 75uS constant is less relevant. MC carts have a frequency response up to 50k because of the low impedance. But since we are dealing with current, impedance is taken out of the equation. If there's a rise, the rise should be more prominent with the Phonoclone.
The AW time constant was a "feature" of the VSPS since the gain non-inverting topology cant go below unity. The HF cut, in other words, cant go on forever(tm) so I figured might was well configure the eq. such that the HF time constant more-or-less sits at 50 kHz.
The eq. stage of the phonoclone is inverting, and I prefer to see the response follow -6dB/octave at high frequencies forever(tm) so that the opamp has no traction up there to start any unpleasantness.
The input stage topology of the phonoclone doesn't come play a role, as I see it.
/rjm
PS. The RIAA values can be replaced with any set of the same ratio. However, if you drop the resistances to increase the capacitance, you'll see that the R3 and R4 quickly become large enough that input current noise starts to be a concern. Move to far the other war, and they are too small for the first stage opamp to drive cleanly. There is surprisingly little wiggle room, actually, maybe a factor of 2x each way.
The eq. stage of the phonoclone is inverting, and I prefer to see the response follow -6dB/octave at high frequencies forever(tm) so that the opamp has no traction up there to start any unpleasantness.
The input stage topology of the phonoclone doesn't come play a role, as I see it.
/rjm
PS. The RIAA values can be replaced with any set of the same ratio. However, if you drop the resistances to increase the capacitance, you'll see that the R3 and R4 quickly become large enough that input current noise starts to be a concern. Move to far the other war, and they are too small for the first stage opamp to drive cleanly. There is surprisingly little wiggle room, actually, maybe a factor of 2x each way.
I'm no tech head. Impedance is still a black hole to me. But I think the zero input impedance topology makes a difference. How much I don't know. It's probably cart dependent, as the stage itself.
http://www.6moons.com/audioreviews/firstwatt/firstwatt2.html
http://www.6moons.com/audioreviews/firstwatt/firstwatt2.html
Time constants & raii resistance values
First off,
I made a big mistake on the Alen Wright time contant - it is more like 3.6 uS (I still am going from memory) 75 uS is part of the regular "curve". When I read my post I could feel blood rushing to my face.
No, I certainly do not think I can hear up there but it does seem to make sense to me. One can "sense" that something is going wrong, though. I realize that hearing is a sense but I am trying to make sense (yikes!) with a semi-poetic ... I better stop now.
Luckily, I found much to answer my concerns within ONVINYLS "my take on the gainclone" thread including illuminations from RJM concerning RIAA component values.
After reading Gary Galo's high prasie of the AD825's sound quality one wonders if it would be useful here?
THANKS
First off,
I made a big mistake on the Alen Wright time contant - it is more like 3.6 uS (I still am going from memory) 75 uS is part of the regular "curve". When I read my post I could feel blood rushing to my face.
No, I certainly do not think I can hear up there but it does seem to make sense to me. One can "sense" that something is going wrong, though. I realize that hearing is a sense but I am trying to make sense (yikes!) with a semi-poetic ... I better stop now.
Luckily, I found much to answer my concerns within ONVINYLS "my take on the gainclone" thread including illuminations from RJM concerning RIAA component values.
After reading Gary Galo's high prasie of the AD825's sound quality one wonders if it would be useful here?
THANKS
Re: Time constants & raii resistance values
Hi Rick,
It would be great if you try and report then...
I am not sure, if rjm's boards will run with more demanding chips like AD797, so you
might need to build your own.
If I ever get behind the secrets of eagle, i will make a board with smd-parts (at least the op-amps).
Rüdiger
rickmcinnis said:
Hi Rick,
It would be great if you try and report then...
I am not sure, if rjm's boards will run with more demanding chips like AD797, so you
might need to build your own.
If I ever get behind the secrets of eagle, i will make a board with smd-parts (at least the op-amps).
Rüdiger
Hi there!~
I have started building the Phonoclone, but have some questions....
I am unable to locate OP27 op amps locally... I was wondering if a high performance op amp like LM4558 or low noise like NE5534, or an LM627would suffice? Which would be better?
Also, the caps that I got are MKT - are they OK? They look like:
What type of transformer should I use? I have two choices at Jaycar that have 12v center tap outs.
One that has 12v at 5amps
or
12v at 500mA
I can probably source others if these are no good.
I notice that on the built board example of the phonoclone, caps C8-C13 are omitted, can you tell me why?
Thanks!!
I have started building the Phonoclone, but have some questions....
I am unable to locate OP27 op amps locally... I was wondering if a high performance op amp like LM4558 or low noise like NE5534, or an LM627would suffice? Which would be better?
Also, the caps that I got are MKT - are they OK? They look like:
An externally hosted image should be here but it was not working when we last tested it.
What type of transformer should I use? I have two choices at Jaycar that have 12v center tap outs.
One that has 12v at 5amps
or
12v at 500mA
I can probably source others if these are no good.
I notice that on the built board example of the phonoclone, caps C8-C13 are omitted, can you tell me why?
Thanks!!
You'll need to go with reliable and stable if your phonoclone is to get off the ground. Use the NE5534 if you can't source an OP27.
MKT caps are ok at this point.
I suggest going with the large 60VA transformer unless you really need a small case.
Capacitors C8-13 have two optional placement points on the PCB. I'm using the smaller "B" position for C8-11. I did choose to omit C12-C13 completely though. C8,10,12,8B,10B,12B are all equuivalent, you can populate as few or as many as you want depending on what bypassing scheme you feel is best. Same goes for C9,11 etc.
Dont take this the wrong way, but its happened often enough in the past that I feel I have to ask: Are you sure the Phonoclone is for you? The VSPS is the one you want for moving magnet cartridges...
/r
MKT caps are ok at this point.
I suggest going with the large 60VA transformer unless you really need a small case.
Capacitors C8-13 have two optional placement points on the PCB. I'm using the smaller "B" position for C8-11. I did choose to omit C12-C13 completely though. C8,10,12,8B,10B,12B are all equuivalent, you can populate as few or as many as you want depending on what bypassing scheme you feel is best. Same goes for C9,11 etc.
Dont take this the wrong way, but its happened often enough in the past that I feel I have to ask: Are you sure the Phonoclone is for you? The VSPS is the one you want for moving magnet cartridges...
/r