Nice table!
ra7- I rarely get far with these discussions but I'll suggest that if the op-amp phono sounds that much different than the discrete, there's some reasonable and measurable explanation beyond the type of device used. Equalization differences, noise level differences or something. IMO, because of the gain differences between discrete and op-amp circuitry, equalization is never exactly the same in terms of break points and corner response shapes. Now, if most (older) records were quality checked on discrete circuits, and my guess is they were, you might well be hearing something closer to what the engineer intended using a lower gain discrete circuit!
ra7- I rarely get far with these discussions but I'll suggest that if the op-amp phono sounds that much different than the discrete, there's some reasonable and measurable explanation beyond the type of device used. Equalization differences, noise level differences or something. IMO, because of the gain differences between discrete and op-amp circuitry, equalization is never exactly the same in terms of break points and corner response shapes. Now, if most (older) records were quality checked on discrete circuits, and my guess is they were, you might well be hearing something closer to what the engineer intended using a lower gain discrete circuit!
Thanks Conrad,
What I first noted when building my first amplifier (1986). That the wiring of my power supply influenced the brightens of my signal.
To be precise I had mounted the power supply in a separate aluminum enclosure. And the amplifiers in a separate enclosure. after moving the voltage stabilizers to the amplifier enclosure the sound improved audible.
That was my first lesson in diy amp technology.
Now I have more overview and have to second conrad because wiring and different grounds make a active behavior that influences the sound. and that is sure the case for such a low input circuit as a phono stage. And I certainly believe that Salas his shunt power supply takes part in the sound experience. As with the amplifier circuit the power-supply plays it roll also.
Regards,Helmuth
What I first noted when building my first amplifier (1986). That the wiring of my power supply influenced the brightens of my signal.
To be precise I had mounted the power supply in a separate aluminum enclosure. And the amplifiers in a separate enclosure. after moving the voltage stabilizers to the amplifier enclosure the sound improved audible.
That was my first lesson in diy amp technology.
Now I have more overview and have to second conrad because wiring and different grounds make a active behavior that influences the sound. and that is sure the case for such a low input circuit as a phono stage. And I certainly believe that Salas his shunt power supply takes part in the sound experience. As with the amplifier circuit the power-supply plays it roll also.
Regards,Helmuth
Yes, that may be the case Conrad. I have nothing against opamps. And in fact Joachim Gerrard published an article in Linear audio that used opamps. I trust him to know good sound, so perhaps it can be done. But probably needs much more care in how it is implemented. Much easier to get great sound from tubes and JFET circuits. I built the Salas circuit also and it sounds superb.
If you mean you moved the voltage regulators closer.... well, thats how they are supposed to be used, almost like capacitors, as close to where they are to do their job, as possible.
I have the vsps with DC coupled outputs, and I can't realy fault it, appart from beig too cheap to brag about.
Hi,
Im for usual no friend of OPamps since I think its somehow weird to generate extremely high gains with extremely low bandwidth just to knock the gain down to less than 10 times and to get sufficient bandwidth. Things get different though when the needed gain is high and maybe even of a similar amplitude-repsonse, like it is the case with DC-servos and phono-stages. As such I tink, that those two are the only audio applications where OPamps might not sound inferior to discrete designs but actually might even be preferrable.
A circuit that offers a great deal of flexibility with regard to the choice of pickup, the pickup matching (R, C and gain), playback EQing and which offers excellent results regarding noise immunity, resolution, dynamics, linearity and distortion values is this one: INA103, Balanced Reference
That is basically the same schematics the Clearaudio Balanced Reference features. A nearly identical circuit (though with an improved PCB layout and an optional symmetrical output) is the PlatINA which can be found at the german forum of the AnalogAudioAssociation under DIY Phonopre INA 103. A description (in german) of the PlatINA and the PCB can be found at USUL´s PlatINA
After the owner the PlatINA gave much better results than the VSPS.
I myself run such a circuit for more than 20 years and it just delivers exactly whats on the vinyl. I hardly ever heard a circuit that was so ´transparent´ in a sense that it virtually vanishes. It lets every pickup shine and let it show You its distinctive character.
Parts are quite ease to source (mostly Digikey) and building should not generate major probs. No screening or tuning is necessary. Its great value for money.
jauu
Calvin
Im for usual no friend of OPamps since I think its somehow weird to generate extremely high gains with extremely low bandwidth just to knock the gain down to less than 10 times and to get sufficient bandwidth. Things get different though when the needed gain is high and maybe even of a similar amplitude-repsonse, like it is the case with DC-servos and phono-stages. As such I tink, that those two are the only audio applications where OPamps might not sound inferior to discrete designs but actually might even be preferrable.
A circuit that offers a great deal of flexibility with regard to the choice of pickup, the pickup matching (R, C and gain), playback EQing and which offers excellent results regarding noise immunity, resolution, dynamics, linearity and distortion values is this one: INA103, Balanced Reference
That is basically the same schematics the Clearaudio Balanced Reference features. A nearly identical circuit (though with an improved PCB layout and an optional symmetrical output) is the PlatINA which can be found at the german forum of the AnalogAudioAssociation under DIY Phonopre INA 103. A description (in german) of the PlatINA and the PCB can be found at USUL´s PlatINA
After the owner the PlatINA gave much better results than the VSPS.
I myself run such a circuit for more than 20 years and it just delivers exactly whats on the vinyl. I hardly ever heard a circuit that was so ´transparent´ in a sense that it virtually vanishes. It lets every pickup shine and let it show You its distinctive character.
Parts are quite ease to source (mostly Digikey) and building should not generate major probs. No screening or tuning is necessary. Its great value for money.
jauu
Calvin
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Another alternative you may want to (re)consider is an op-amp based design. If you take a look on my web page below in the phono-amp section there is a discussion on op-amp based designs. For something really simple but still with adequate performance you could try the classic Baxandall circuit which is also discussed. Whatever route you rake, good luck!
The INA103 has some obvious attractions and at some stage i used it with a very low output MC. Certainly seemed to perform well. More recently i compared it in a first stage of a split riaa and sound-wise modern opamps ate it for breakfast. Disjointed highs, weak bass, very disappointing.
If you are going to use an op-amp gain block in an RIAA, then a single stage is best on paper. Split RIAA designs always involve greater tradeoff's.
Necessary for what? For every person who enjoys the great galvanic isolation transformers offer in this application i'll find you ten who have problems with hum pick up.
That's exactly what the transformer eliminates. Even touching a pin of the phono cartridge with a finger causes no hum.
Rod's TL072 basedv design is nice and simple, but I think a 5532 with lower value feedback impeadances will give you lower noise and ower distortion.
the Audio Sector Phono Stage blew my mind away - I do believe boards are still available for it. It's basically an op-amp unit with "zero" impedance - suitable for low MCs only. Lots of suggested tweak parts, I built mine using lower-grade stuff - still the most transparent I've ever heard, besting my old Threshold FET-10/HL and Graham Slee V.
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