Well that is the difference between an 'amateur' design and a commercial design, I guess.
I had to make a pretty good phono stage without using low noise jfets for Parasound.
I am stuck with what is available in IC's.
Now, what do I optimize for?
MM cartridges, that are not optimized unless you know and dial in the load capacitance?
MC cartridges that don't care quite as much about loading, except for 'committed' audiophiles?
Also, typical music listeners who might buy this product are usually not tech. savy and they really would prefer a plug-and-play unit.
What is the best trade-off without adding too much complexity?
I compromised with both MM and MC, and barely got away with either. That is the JC-3.
I had to make a pretty good phono stage without using low noise jfets for Parasound.
I am stuck with what is available in IC's.
Now, what do I optimize for?
MM cartridges, that are not optimized unless you know and dial in the load capacitance?
MC cartridges that don't care quite as much about loading, except for 'committed' audiophiles?
Also, typical music listeners who might buy this product are usually not tech. savy and they really would prefer a plug-and-play unit.
What is the best trade-off without adding too much complexity?
I compromised with both MM and MC, and barely got away with either. That is the JC-3.
What I have said on this so far is based on memories retained when interpreting these scans years ago. I have to find and retrieve these files.
The moving/non moving has to do with the vinyl properties.
One of the long thought of/to be implemented projects, is to study the mechanical impedance vs frequency of vinyl records, using a driven cartridge as a point exciter/measurer.
George
Chris
Try to measure the inductance of a speaker driver. It will drive you crazy. You have to immobilize the moving coil by gluing with a hard glue in order to stabilize the measurant.
George
For a REAL PHONO PREAMP wait for the Constellation Perseus to come to your audio convention soon! '-)
The blocked measurement of the driver will only provide the blocked values.
The inductance measured while it is free is consistent with what the terminals will present to an amp or a crossover.
The free inductance will also have the adders of inductance drop and resistive increase as a result of the coil moving in the gap and creating additional lenz effect as well as motional derived eddies.
To be able to truly model a driver, it has to be in it's final enclosure. Once you get above frequencies where the cone mass prevents movement, you see easily the blocked values, but they aren't of much use.
jn
ps..besides, what's wrong with negative inductance???
These complexities are among the reasons that motional feedback using a real-time measurement of the voice coil inductance is difficult.
That was a very nice article and I had a chance to see the one you built and measure it at BA last year. Nicely done.
Yes, I did. I'd love to have it back to use as a reference while I'm finishing up my new MM preamp design.
This reminds me of a series of cartoons once in a popular automobile magazine back in the '50's and '60's, with a couple of guys who had 'Flatheads Forever' on their T-shirts.
These guys were DETERMINED to keep flathead engines viable by any means possible, including supercharging. Of course, even in the USA, overhead valves were becoming the standard, and overhead valves for race cars, but these guys persisted.
These guys were DETERMINED to keep flathead engines viable by any means possible, including supercharging. Of course, even in the USA, overhead valves were becoming the standard, and overhead valves for race cars, but these guys persisted.
Indeed, despite the huge shortcomings of vinyl, some of us are committed to extracting the most we can out of it. Optimized preamps for MMs are an interesting design problem which the fashion audio designers apparently can't cope with. Fortunately, guys like Bob Cordell have shown that smart guys who aren't stuck in a narrow groove, so to speak, can be up to the challenge.
Go, Bob, Go! Keep those IC's in the path of discrete's ! Why bother with discrete's all the way?
I sometimes wish that those, who know better, take up the challenge and enter the 'fashion audio' race to prove their claims.
If truth be known, there are no shortcomings in any media capable of recording sound, that have been exploited over the years, that are not capable of delivering captivating, convincing, long term pleasurable sound. Now, if we could only convince a few more people of that ... 😉
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