Hi Jack,
As far as I know, the LSK489 was not available at the time. The LSK489 is a lower-noise device that is fully compatible with the LS844. It derives from an improved process that has much less generation-recombination (GR) noise. See my LSK489 app note on the Linear Systems web site.
BTW, the new LSJ74 p-channel complement to the LSK170 looks quite good.
Cheers,
Bob
If you're going to revive this thread I will say the LSK489 is very successful in Bob's circuit. LS has rethought the LSJ74 since Bob's comment, you should check the current web site.
Dear Scott Wurcer
Any info about replacing original LSK389 (MC stage) with other JFET`s or `389 best device for MC input stage?
Also I`m interesting for replacing OPAMP`s with modern parts.
Do you have a VinylTrak? Any comments\listening tests available?
Are VinylTrak actual at this moment (after 5 years from original article publishing)?
Any info about replacing original LSK389 (MC stage) with other JFET`s or `389 best device for MC input stage?
Also I`m interesting for replacing OPAMP`s with modern parts.
Do you have a VinylTrak? Any comments\listening tests available?
Are VinylTrak actual at this moment (after 5 years from original article publishing)?
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Not really, but many folks here have used the BF862 (SMT only) in MC stages with lots of happy results. I built a highly simplified all FET RIAA roughly based on Bob's input stage as an experiment in seeing how little one can get away with. There's a thread on it here. I'm very happy with the results and hope to do a shoot out with some good valve pre-amps soon.
http://www.diyaudio.com/forums/anal...erential-single-phono-preamp.html#post5042118
Hi Victor,
Thanks for the heads-up. I don't have the schematic in front of me, but I'll assume you are correct.
Cheers,
Bob
Thank you Scott!
I think I`ll continue with VinylTrak.
At this moment I perform some modelling with LTSpice and capacitors recalculating for time constants (using well-known Stanley Lipschitz paper as reference) .
I have several tens 20 nF and 34.8 nF KS-Series from Siemens-Halske.
There are some interesting moments with DC-Servo behavior and MC Stage (at least with LTSpice).
Need perform some checks.
-- Regards,
Victor Levandovsky
I think I`ll continue with VinylTrak.
At this moment I perform some modelling with LTSpice and capacitors recalculating for time constants (using well-known Stanley Lipschitz paper as reference) .
I have several tens 20 nF and 34.8 nF KS-Series from Siemens-Halske.
There are some interesting moments with DC-Servo behavior and MC Stage (at least with LTSpice).
Need perform some checks.
-- Regards,
Victor Levandovsky
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I have not used the OPA1611, so I can't recommend one way or the other. Always bear in mind stability issues, especially if the op amp has more bandwidth or if it is not unity-gain stable. The 2134 is a good op amp, and I'm not sure changing it out would make much difference.
The preamp was done a long time ago, and I haven't given any thought to what I would change. The LS844 would definitely be changed to the lower-noise LSK489.
Cheers,
Bob
I have built the MM version of the Vinyl Trak pre-amplifier. I've been enjoying it for a few years now and am constantly reminded how good it sounds. Yes, the servo connections are incorrect in the schematic so you'll need to modify for proper behavior. I used the LSK489 at the input. No issues there.
For what it's worth, I replaced the 2134 op-amps with Analog Devices ADA4627 JFET input op-amps. I had some samples in-hand, so what the heck - put them to use. They work just fine in this circuit (no oscillations or other bad behavior that I could detect) and the datasheet applications section even says for "high end, professional audio." So I've got that going for me.
I have not built or used the MC circuit but my PCB has hooks for it. Some day I will get around to it. I'd be interested in your take on it if you ever get it built and installed in your rig.
For what it's worth, I replaced the 2134 op-amps with Analog Devices ADA4627 JFET input op-amps. I had some samples in-hand, so what the heck - put them to use. They work just fine in this circuit (no oscillations or other bad behavior that I could detect) and the datasheet applications section even says for "high end, professional audio." So I've got that going for me.
I have not built or used the MC circuit but my PCB has hooks for it. Some day I will get around to it. I'd be interested in your take on it if you ever get it built and installed in your rig.
I test MC stage with LTSpice and have a very encouraging result using standard components value.
I recalculate LF equalization for other capacitance (I have 34.8nF and 20 nF).
I decide to increase capacitance (and decrease resistance) for lowering noise.
Correction error inside 0.02 dB (60.7-60.68 dB) range...
Gain
Noise (Output and Input)
But something wrong with my MM calculation....
((((
I will be grateful for the help with MM simulation and recalculating MM HF stage in dumped mode.
BTW - any differences between "Damped" and "Conventional" Equalization during listening tests?
I recalculate LF equalization for other capacitance (I have 34.8nF and 20 nF).
I decide to increase capacitance (and decrease resistance) for lowering noise.
Correction error inside 0.02 dB (60.7-60.68 dB) range...
Gain
An externally hosted image should be here but it was not working when we last tested it.
Noise (Output and Input)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
But something wrong with my MM calculation....
((((I will be grateful for the help with MM simulation and recalculating MM HF stage in dumped mode.
BTW - any differences between "Damped" and "Conventional" Equalization during listening tests?
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