If I were to continue to do a full blown pre-amp design, then I have already incorporated both a MM & MC. presently the 7.1 pre-amp. Presently uses a PLR MC gain cell & a Denis Colin's MM RIAA/MM gain stage.
I do however like and heard some good reviews of the HPS5.1, since it does both, just need to adjust the gain cell for both types(relays?). I did read that the author of HPS5.1, Ovidiu Popa did or was to do an article in Linear Audio of an improved model. Recall about change or cost reduction of the NS/TI LMH6321power buffer. Can't find it on Jan's web site however.
Lots of options!! Also have designed a Si4735 tuner, working on an improved version using a Si4770.
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I have all of the LA issues and I've not seen any Popa preamp update following his No. 1 issue article (which provoked LTEs from me and Vogel, which should still be accessible on the LA site). Recently Cordell did a piece on a couple of phono preamps, including a controversial approach to realizing part of the high frequency time constant by a low-value input termination. This certainly works but requires detailed knowledge of the cartridge impedance, and of course all are different, and presumably as well vary within a model from sample to sample. Very DIY-oriented to say the least, unless one undertakes to design a preamp that includes cartridge characterization as one of its features.
I'll probably have to confine my activities for publication to just the source switching, since I've got a bunch of preamp things, including phono ones, in the works (a labor, on and off, of a good many years now), and I'm waiting for possible funding to pursue manufacture. If this were only a hobby things would be different, but to give things all away right now would possibly be counterproductive --- although I've been doing a lot of that lately
If I can't get funding I may write a little book about one aspect of things, a certain path to poverty for any but the independently wealthy I did simulate the switching transients with the source selector after concocting the timing generators for switch drive, and things look pretty tolerable even though there is a net capacitive kick that takes about 5us to settle completely (which is not too bad, especially with discrete FETs). I may for fun do a design in which the single-ended input is converted to differential ahead of the switching, a reversal of the usual situations dealing with already-balanced inputs, so that to the extent the transients are matched, the output, balanced or converted back to single-ended, has transient cancellation. This entails another noise penalty though, and as remarked with uC control and something following with a mute function, such pop/thump suppression in the selector itself is of little interest.
Hi Brad, if you wish, we can exchange ideas off line, I'd like to hear about your business plan, to see about the extent of your "I'm waiting for possible funding to pursue manufacture." I do not have a job these days, so kinda retired, might be interested depending on your plans.
I also put the original D. Self variable tone control ckt in the pre-amp design. My first pspice sim Contemplated repl. mech pots with DAC's, digipots or PGA2320 etc. I ask, who needs tone controls to add this big cost/complexity?
Sounds like you are plugging along with fet switching, exciting.
Wonder if "maxw", is still following along or we lost him?
Just a thought, instead of a switch, to select sources, use the CS3318 as a the switch element and sum the outputs, saves a lot of HW.
I also put the original D. Self variable tone control ckt in the pre-amp design. My first pspice sim
Contemplated repl. mech pots with DAC's, digipots or PGA2320 etc. I ask, who needs tone controls to add this big cost/complexity?Sounds like you are plugging along with fet switching, exciting.
Wonder if "maxw", is still following along or we lost him?
Just a thought, instead of a switch, to select sources, use the CS3318 as a the switch element and sum the outputs, saves a lot of HW.
The funny thing is, I decided to post this switching approach as a general purpose example, and found this thread while looking for a somewhat related application of electronic switching, which in turn was prompted by the desire for an electronically adjustable cartridge loading capacitor. I haven't published on that latter circuit yet, but reading this one decided I'd get the line level source selector out there. Again, I'm pretty confident that the source selector must exist somewhere, but it hasn't turned up via online searching as yet. I did recheck Self and it is definitely not in his recent book. I have a vast technical library and it may be in one of the books, but most of them are in storage and with much of that in boxes. My database is about half-finished, which will make it easier to locate things.
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