Something not completely on-topic but of interest to you record guys:
I have just placed on 'on-line article' at the linearaudio.net website listing many record manufacturers along with the pre-emphasis they used. If you thought RIAA is a standard, check out the list!
The list has been compiled by Katsuyoshi Miguchi, the owner of SoundBox, an Antique Audio shop in Tokyo. It was originally published in Radio Technology magazine in Japan in October 2011. Reproduced here by kind permission of the Author and the Editor of RT magazine. I am indebted to Mr. Nakamura for arranging the permissions and for providing the English language translation.
If you have any additions and/or corrections to this table I would very much like to receive these, and I will update the list as needed. The last update will be noted at the end of the list.
Comments welcome,
jan didden
I have just placed on 'on-line article' at the linearaudio.net website listing many record manufacturers along with the pre-emphasis they used. If you thought RIAA is a standard, check out the list!
The list has been compiled by Katsuyoshi Miguchi, the owner of SoundBox, an Antique Audio shop in Tokyo. It was originally published in Radio Technology magazine in Japan in October 2011. Reproduced here by kind permission of the Author and the Editor of RT magazine. I am indebted to Mr. Nakamura for arranging the permissions and for providing the English language translation.
If you have any additions and/or corrections to this table I would very much like to receive these, and I will update the list as needed. The last update will be noted at the end of the list.
Comments welcome,
jan didden
Sorry for the misleading wording I used - of course no "wires" are used to connect stuff. All the ground planes are brought together at the star ground with PCB traces. This is also needed to make construction simpler and foolproof. I just wrote "wires" to indicate that separate traces were used to bring all the potentials together in one place.
I fully agree to your comments, antennae are no good in such a circuit that shall deal with nV signals! From my experience, for ground planes, it is important to think in currents. Here, we have DC(+noise) and signal currents, and the target is to not have signal currents and noise currents create voltage drops across the input voltage loop, to worsen S/N.
So in this design, signal current in the output stage --> small loop with the voltage regulators (well, not super-small but good enough I think, and very good GND coupling, far away from the input stage). That will work perfectly if the output (RCA) connectors) are isolated, and the grounds separated on the backplate of the case. What would happen if the grounds on the RCAs were connected? I think it would work no more perfect but just nice, as the GND connection between the regulator and output stage is much lower impedance than the "other" path. Would be interesting to measure that....
Further to this design, input voltage (and current) loop has the electrolytics in there, so this loop needs to run separate. Same thing for the structures that filter the cascode voltages - very little currents here once they are charged, so to not contaminate these a extra ground connection is put in place. And the RIAA ground is separate too, as there is signal-dependent ground current which should not be contaminated with other currents.
Could the star ground be at the output, e.g. between amplifier and regulators? Probably yes, as long as the input loop is connected "differentially" to the input RCA, that is, with separate ground. That way no (supply or output signal dependent) current will flow in that loop and create noise.
Just my two cents..... comments welcome
(And if the board doesnt work and makes lots of noise, I will have to eat my words ;-))))
I fully agree to your comments, antennae are no good in such a circuit that shall deal with nV signals! From my experience, for ground planes, it is important to think in currents. Here, we have DC(+noise) and signal currents, and the target is to not have signal currents and noise currents create voltage drops across the input voltage loop, to worsen S/N.
So in this design, signal current in the output stage --> small loop with the voltage regulators (well, not super-small but good enough I think, and very good GND coupling, far away from the input stage). That will work perfectly if the output (RCA) connectors) are isolated, and the grounds separated on the backplate of the case. What would happen if the grounds on the RCAs were connected? I think it would work no more perfect but just nice, as the GND connection between the regulator and output stage is much lower impedance than the "other" path. Would be interesting to measure that....
Further to this design, input voltage (and current) loop has the electrolytics in there, so this loop needs to run separate. Same thing for the structures that filter the cascode voltages - very little currents here once they are charged, so to not contaminate these a extra ground connection is put in place. And the RIAA ground is separate too, as there is signal-dependent ground current which should not be contaminated with other currents.
Could the star ground be at the output, e.g. between amplifier and regulators? Probably yes, as long as the input loop is connected "differentially" to the input RCA, that is, with separate ground. That way no (supply or output signal dependent) current will flow in that loop and create noise.
Just my two cents..... comments welcome
(And if the board doesnt work and makes lots of noise, I will have to eat my words ;-))))
Hello Jan and happy new year! Yes that is quite interesting. There is a phono preamp for the purpose:
http://www.emt-studiotechnik.de/JPA66 E.htm
For the paradise phono preamp, I have taken the freedom to
- include a connector where external compensation networks can be connected (please no external ground connection though, and proper shielding!!)
- put a placeholder for a additional resistor so that people who want to implement the "Neumann" time constant (3.18us) can do so - others just put a wire in place
best regards
Wow that EMT lookes great! Do you own one?
I know of one other similar preamp, the "KAB Souvenir EQS MK12 Disc Remastering Preamplifier".
jan
wish i did... read a test report and they say it sounds great, very clear and lots of details.... has tubes though and a input transformer ;-)
it would fit perfectly to my EMT 928 and the 929 tonearm i had for christmas, from the person who knows best what i want - myself ;-))