I asked before, is there a disagreement with other published work or not? Chapter 3 below (a reference is not needed). BTW distortion from a first order voltage coefficient is 1/4 with two devices in series, simple Taylor series expansion.
http://www.nanovolt.ch/resources/low_distortion_oscillators/pdf/low_distortion_oscillator_design.pdf
And again we, TI, and others make audio demo boards with off the shelf SMT parts that do -110dB at full scale THD (DUT limited for the most part). We once sat down and did the series parallel thing on a differential receiver (PITA with SMT) to no avail.
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Scott,
Are you really not following? I am comparing capacitor types and manufacturers for use in general purpose audio. What results I get will be shown.
As to the weighting of the distortion components, I haven't show that yet to see if others get up to speed on the first bit. Or do I need to mention the folks who miss the importance of reciprocity in the measurement technique again?
Are you really not following? I am comparing capacitor types and manufacturers for use in general purpose audio. What results I get will be shown.
As to the weighting of the distortion components, I haven't show that yet to see if others get up to speed on the first bit. Or do I need to mention the folks who miss the importance of reciprocity in the measurement technique again?
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And if there is no price difference would you buy the higher distortion capacitor? With resistors some of the lower cost ones are the best. But it is trendy to spend ridiculous money on strange parts.
Under what is becoming a standard test, now used by several resistor manufacturers, adding the capacitor guys can't hurt.
Can we talk about folks in production who have sudden changes in supply and want a decent simple QC test?
I still aim for 160 dB! Actually getting closer.
I've attached a plot from that thread, which is an SL-1200 Mk4. Possibly the lowliest in JP's collection. The plot is speed stability over two rotations overlaid. In this case there is possibly a worn bearing, but the result is still very good compared to other TT measurements. And people worry about DAC jitter
Sadly I don't have anything worthy for exchange
. But thank you.Attachments
Standard DAC jitter using a crystal oscillator is not going to be audible. Not unless there are other misbehaving issues in the silicon. It's amazing what keeps some people up at night. I'm amazed at how steady my current tables are. It wasn't that long ago when speed stability was a real problem.
-Chris
-Chris
I've attached a plot from that thread, which is an SL-1200 Mk4. Possibly the lowliest in JP's collection. The plot is speed stability over two rotations overlaid. In this case there is possibly a worn bearing, but the result is still very good compared to other TT measurements. And people worry about DAC jitter
Doesn't look super impressive, but how bad are other ones?
IIRC, The McIntosh C-26. Stone conventional (for the day) three transistor topology.
Hi Bill,
I have my hopes pinned on the test LP we are hopefully having made. I haven't anything else since they went with my company when I sold it. Accessing the signal to record on a computer should be fun. I wonder if a laptop built in sound would be okay? It's just a steady tone and we aren't worried about fidelity. Otherwise I can't see myself moving the turntables to the test bench downstairs.
-Chris
I have my hopes pinned on the test LP we are hopefully having made. I haven't anything else since they went with my company when I sold it. Accessing the signal to record on a computer should be fun. I wonder if a laptop built in sound would be okay? It's just a steady tone and we aren't worried about fidelity. Otherwise I can't see myself moving the turntables to the test bench downstairs.
-Chris
Hum ... my Technics use a PLL: high power when need high acceleration, low on "steady state". And the motor (direct drive) has a great number of poles.
Anyway, it is enough to measure the wow and flutter: 0.025%.
And the speed accuracy: +-0.002%.
I wonder if any heavy plate powered by belt with an AC " motor can be better ?
Anyway, Turntables are just good enough for the museum, nowadays ;-).
Some are really awful, but usually becuase they were in need of a good tuneup. It's all in here Turntable speed stabilty
Chris: Laptop sound card should be fine. As soon as I get a few £ spare I'm going to pick up a focus scarlett 2i2 for ADC to PC duties as that seems to hit a sweetspot. Oddly SPDIF to USB adaptors are few and far between and the one I found was the same price as the Scarlett! So on the principle that something that works is better than a pile of boards that need soldering and boxing...
I don't recall the post, but in the Part II , someone piped in that they can't tell the difference between the RTR and and vinyl in listening trial at the studio, but everyone can hear the digital compared to the RTR/vinyl. We're talking about people that do this as a business. My experience as well, digital is simply not as appealing as vinyl... The only museum I'm recommending is my house.
Bill, I think I'm going to get all my TT advice from you first. You're avid in all the topics about them, it seems. And you were not pulling my leg, the one you showed is far from the worst!
Well bear in mind I've gone from thinking I knew something to realising I actually knew nothing! However using John's signature as a mantra I am going back to first principles in a lot of areas to try and sift legend from reality. A long way to go.
And I fully accept that I am spending time on an old and superceded technology, but that pretty much defines most hobbies
And I fully accept that I am spending time on an old and superceded technology, but that pretty much defines most hobbies
Are-they kidding ?
It is always a moment of mourning, when we listen in studios to the first samples of a Vinyl, right out of the press. Even when we had travelled across the planet in the hope to find a "Magic room" for mastering ;-)
Even between US imports and the same vinyls produced in France or Germany, the difference was Obvious. (In favor of US).
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Thanks. That's interesting as ISTR Doug Self analysed that topology in one of his books and came up with a number of improvements. I wonder if the post Self version now passes the Holman tests.
The discrete transistor topologies of both Dyna and McIntosh in the 1960's were very primitive compared to later phono preamp designs. In fact, we rejected these designs and stayed with their tube versions from the same companies. It must be understood that individual transistors at the time, were not necessarily cheap, and probably cost as much as the tubes they replaced, yet were MUCH more nonlinear. It is no wonder that the C26 failed the Holman test. Also, the audio designers of the day were forced to attempt to design with bipolar devices, just because of marketing pressures, without any necessary background, but a handbook as to do it.
Later, we learned from the IC designers, and with lower individual prices, how to make successful phono stages. For example, I stuck with the Dyna PAS-3X or the McIntosh C22, (the Marantz 7c tube preamp would have been OK as well), until I replaced it with the Levinson JC-2 in 1974.
Later, we learned from the IC designers, and with lower individual prices, how to make successful phono stages. For example, I stuck with the Dyna PAS-3X or the McIntosh C22, (the Marantz 7c tube preamp would have been OK as well), until I replaced it with the Levinson JC-2 in 1974.
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