Ah, interesting device, esp for 1/f. However I note the dreaded input bias cancellation circuitry (the input bias current sign is undefined), so the current noise figure probably assumes identical input impedances - its not clear. And the current noise is the same as the NE5534A anyway, and its more expensive - so not clear its any better for MM.
Also the NE5534A has _guaranteed_ noise performance, which the 2210 apparently lacks - another reason not to be too hasty.
I don't think the high rails in a phono stage would get you anything. Keep in mind that the output of the phono pre is going to a line stage and then out to a power amplifier. So if the phono pre were putting out 2Vrms, that could drive most power amps to clipping without an intervening line stage. That's 2.8V peak swing above & below 0V. A pair of 6V Vregs would get you enough rail voltage. Going higher won't hurt; it's just that you won't be able to use it all. My phono pre uses +/-5V regulators, and it sounds fine on the loudest passages.
I finally finished building and testing the LT1115 preamp. Indeed a pleasant surprise!
"No" noise, no hum, sounds nice with my old Rega and Ortofon MC30.
Now this ugly duckling PCB will live in a suitable case, formerly occupied by a Hiraga MC preamp.
Finished board:
Testing:
RIP - soon:
(Hiraga MC at the bottom)
If I were to make this amp again, I would probably drop the FET and use a resistor. Using the original FETs seemed like a cool thing to do, but they have to be fine tuned to give the desired 2mA. With components according to the app note, the difference between the two channels was BIG. 2.1mA vs 1.2mA. No difference in sound was detected, though. And I would make a new, 2-layer PCB with a more compact layout.
Will it happen? Guess not...
"No" noise, no hum, sounds nice with my old Rega and Ortofon MC30.
Now this ugly duckling PCB will live in a suitable case, formerly occupied by a Hiraga MC preamp.
Finished board:
Testing:
RIP - soon:
(Hiraga MC at the bottom)
If I were to make this amp again, I would probably drop the FET and use a resistor. Using the original FETs seemed like a cool thing to do, but they have to be fine tuned to give the desired 2mA. With components according to the app note, the difference between the two channels was BIG. 2.1mA vs 1.2mA. No difference in sound was detected, though. And I would make a new, 2-layer PCB with a more compact layout.
Will it happen? Guess not...
No problems at all with the Hiraga MC...
But this little card was housed it the shown box together with 2 big accumulators and a charger.
Thought it was a good thing. But it was too much hassle.
Now I want to put the Hiraga in an ordinary preamp box togehter with a suitable PSU, some RIAA amp + AUX inputs + volume + output buffer.
At least, that is the plan.
Now I must first get used to this new toy!
🙂 morten
But this little card was housed it the shown box together with 2 big accumulators and a charger.
Thought it was a good thing. But it was too much hassle.
Now I want to put the Hiraga in an ordinary preamp box togehter with a suitable PSU, some RIAA amp + AUX inputs + volume + output buffer.
At least, that is the plan.
Now I must first get used to this new toy!
🙂 morten
Threads about phono preamplifiers are usually put in the "Analogue source" forum. "Solid state" is mostly used for solid-state power amplifiers.
I did not realize until now that Ananlogue Source was a separate segent of the Forums. Thanks for enlightening me, Bonsai.
Agreed.
Agreed.
For that reason, I measured the noise current of an OPA2210 with unequal impedances some time ago and the result was quite close to 0.4 pA/√Hz.
The jfet as mounted on the diagram in the datasheet sends -15V to output pin 6 of the lt1115 and consequently to the input of the lt1010! Is this normal?
Yes. The FET is incapable of pulling the op-amp output to -15 V, all it does is pull some current so the op-amp output stage works as a single-ended class A stage.
Hello morten,
Would it be possible to share the design (typon) of your pcb?
I made a provisional assembly of the circuit and the jfet as mounted on the diagram in the datasheet sending -15V to the output of the lt1115 and therefore to the input of the lt1010!
Is this normal?
I am not sure what you ask for... in #34 is the schematic and the PCB. I would like to help if I can!
The JFET only draws 2 mA or so from the OPAMP to keep it working in class A, always. No -15V is involved.
