A sand state phono preamp utilizing the LND150, or some other depletion mode device (Infineon and Clare have some interesting candidates) might be an interesting thing to try. There's no filament power to worry about, for one. Mosfets have come a long way in quality, so they may not be all that noisy. There's a high-end commercial RIAA offering using the HV Infineon depletion mode part.
The US version of the amp is at least labled differently than the German schematic I have.
The German cover sheet calls out for a tape input. Instead the US version calls for an "Extra" input.
The back connectors include Magnetic, Crystal, and Extra inputs and Tape output. So the "Extra" is probably exactly the same as the "Tape" input.
RIAA is 12AX7 two stage. Crystal input feeds a 10:1 divider to the Magnetic input.
I can't find the coversheet with the specificatins right now, however I believe it called for the Crystal input to be in the range of 37mV which would imply that some form of amplification would be necessary.
The German cover sheet calls out for a tape input. Instead the US version calls for an "Extra" input.
The back connectors include Magnetic, Crystal, and Extra inputs and Tape output. So the "Extra" is probably exactly the same as the "Tape" input.
RIAA is 12AX7 two stage. Crystal input feeds a 10:1 divider to the Magnetic input.
I can't find the coversheet with the specificatins right now, however I believe it called for the Crystal input to be in the range of 37mV which would imply that some form of amplification would be necessary.
Last edited:
If there is a separate phono preamp, many things are possible. If not, the depletion mode mosfet option may be worth a look, as the extra few mA for a parsimoniously designed RIAA stage should not wreck the power supply, especially if the preamp is designed to drive only the in-box impedance, which should be pretty high.
Does anyone know if this site is reputable or have an account there? I think that they might have a copy of the schematic that came up on a google search but they require an account to view it and probably a fee to download. Looks preeeettttyyyy sketchy to me.
Xin Yi Electron - All service maual
Xin Yi Electron - All service maual
We might be able to solve it this way:
I'm assuming that the STA-400X is basically the same except for the tape input and the separate crystal/magnetic inputs. So if the tape input does not use a preamp of any kind (same as the extra) then if the 400x has some tubes that the 100x doesn't have then that has to be a stage the 100x doesn't have and it can be concluded the 100x has no phono preamp. Maybe.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.