I'm in the processes to design a RIAA amp with both MM and MC capability but I can't figure out (using Google) which ranges of capacitance and resistance I should have. The plan is to have a 8 position DIP switch for each channel. My Ortofon FF15 needs 47 kohm and 400 pF load but how about the MC cartridges?
(I will show my work later on 🙂 )
(I will show my work later on 🙂 )
Hi PerAnders....
If you wanna do it right, make it as versatile as possible.
Use 16 pos. dip´s pr. channel. I know, I sometimes miss the possibility between 2 settings.
Also some MM´s prefer different to 47K, to be as flat as possible. Sometimes cap. loading isn´t enough.
And by the way..... MC´s are NOT immune. You just need to be in the nF area.
My suggestions would be for MC: 30, 60, 100, 200, 470, 750 & 1000 ohm with the possibility of a 1nF cap.
For MM: 33K, 47K, 75K & 100K + 47pF, 100pF, 220pF, 330pF & 470pF.
That would meet the need of most cartridges on the market today.
btw..... Didn´t your homepage have a well constructed discreet riia with a lot of components in the past??
If you wanna do it right, make it as versatile as possible.
Use 16 pos. dip´s pr. channel. I know, I sometimes miss the possibility between 2 settings.
Also some MM´s prefer different to 47K, to be as flat as possible. Sometimes cap. loading isn´t enough.
And by the way..... MC´s are NOT immune. You just need to be in the nF area.
My suggestions would be for MC: 30, 60, 100, 200, 470, 750 & 1000 ohm with the possibility of a 1nF cap.
For MM: 33K, 47K, 75K & 100K + 47pF, 100pF, 220pF, 330pF & 470pF.
That would meet the need of most cartridges on the market today.
btw..... Didn´t your homepage have a well constructed discreet riia with a lot of components in the past??
make 0pF and option as cables often have 150-200pF already, which is enough for a lot of MMs. IMO anyway.
That was long time ago, besides I didn't have any feature for tuning the load. This time it will be with SMD parts.
Conclusion right now for MM:
47, 100 and 220 pF which gives me up to 367 pF
100 kohm and 91 kohm => 100 and 47,6 kohm
The thought was using four DIP switch positions.
47, 100 and 220 pF which gives me up to 367 pF
100 kohm and 91 kohm => 100 and 47,6 kohm
The thought was using four DIP switch positions.
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In most cases this is right, but not in all - check out
http://www.extremephono.com/Loading.htm
also
http://www.hagtech.com/loading.html
https://forums.stevehoffman.tv/threads/proper-cartridge-loading-can-make-a-big-difference.729477/
https://sound-au.com/articles/cartridge-loading.html
Not mentioned in most cases concerning very low level MC cartridges with very low DC resistance of the coils is the fact, that the input impedance of first gain stage must be low (common base circuit) like on this examples:
https://www.diyaudio.com/community/threads/jean-hiraga-mc-circuit.4191/
https://www.diyaudio.com/community/threads/mark-levinson-jc-1dc.372134/
https://www.diyaudio.com/community/...etween-mark-levinsons-jc-1-and-jc-1dc.243267/
If input impedance is high without load resistor, and only load resistor (10-22R in most cases) makes the input impedance low, sound character provide muddy character and with resistors above 39R more and more crispy - this I have observed in the same kind by use of Audio Technica's ART-ONE and ART-7 (not at the ART-9) so as on an old Ortofon MC cartridge (one with lowest output voltage - I don't know the model).
According this observations I recommend the use two MC-inputs, one with low input impedance (common base input) and one with high input impedance (common emitter). If you want to work with op-amps, this can be realized in the most to find non inverted mode (high impedance) and inverted mode (low impedance) for very low voltage/low DC impedance MC cartridges - go to
https://phonoclone.com/diy-pho4.html
https://web.archive.org/web/20060215195055/https://www.sakurasystems.com/products/47phono.html
https://forum.audiogon.com/discussions/cartridge-options-for-current-gain-phonostages-47-labs
if it is ensured that no such MC cartridges are used, i.e. only medium/high output MC cartridges, you can of course work without them and simply provide a MC output transformer for these special cases.
Neither have I. I was told aa cap didn't make a difference with MC cartridges.
I just might empty my damping trough.
I just might empty my damping trough.
I measured a few DIN-5 to dual RCA tonearm cables for capacitance.
The highest is 250pF for a longer cable than most.
The lowest is 85pF for a shorty I had made for me by Blue Jean Cable.
What is the input capacitance of your preamp?
The highest is 250pF for a longer cable than most.
The lowest is 85pF for a shorty I had made for me by Blue Jean Cable.
What is the input capacitance of your preamp?