http://theturntableshop.com/wp-content/uploads/2014/05/009-e1400142301974.jpg
Oh my. that is erm, interesting.
Oh my. that is erm, interesting.
Perhaps you are referring to the Transcriptor Vestigial tonearm. A friend of mine had one... a long time ago. Very cool looking arm and table.
With that lego cartridge head it reminds me of the 744 set with its incredibly fiddly string driven crane.
Transcriptors Vestigal tonearm | Stereophile.com
Then go to Manufacturer’s comments
Kirchhoff, brilliant !
George
Then go to Manufacturer’s comments
Kirchhoff, brilliant !
George
That arm sets out to do mechanically what we are discussing to do electronically. Below c 180Hz cartridge response to out-of-phase content will roll off in a classic 40dB/decade 2nd order filter response.
Just don't ask what happens near the resonant frequency for any vertical content. With enough damping though it might just work, sort of, IMO.....?!
OK, swift retraction after a common sense attack! I can't obtain anything like the 180 Hz resonant f mooted by the article/response. Just the mass of the cartridge alone must be too much inertia in any plane, vertical or not, to obtain anything like as high resonant f as that. The spring is the cartridge suspension compliance, of course. Retract, retract !
I can blame the huge ego of the designer for that typical case of lack of communication btn G. Holt and D. Gammon but we shouldn’t be confused by that (it happens at this site as well).
IMO, important achievement with this design are
a) the efficient decoupling btn lateral & vertical resonances of the arm/cart combo.
b) The lowering of the moment of inertia at the vertical direction (I would say at the expense of increasing it at the horizontal direction).
If D. Gammon would have kept a cool head, most probably we would have been in position to read of some further detailed measurements and better explanations about the origin of 2Hz, 5Hz, 180Hz resonances (if the 180 Hz resonance is due to “feedback” along the arm, this will not cause 2nd order LP roll off below this frequency).
George
IMO, important achievement with this design are
a) the efficient decoupling btn lateral & vertical resonances of the arm/cart combo.
b) The lowering of the moment of inertia at the vertical direction (I would say at the expense of increasing it at the horizontal direction).
If D. Gammon would have kept a cool head, most probably we would have been in position to read of some further detailed measurements and better explanations about the origin of 2Hz, 5Hz, 180Hz resonances (if the 180 Hz resonance is due to “feedback” along the arm, this will not cause 2nd order LP roll off below this frequency).
George
A very popular arm here in the 70's. Locally nick-named the vegetable. That with a Shure V15 plus an AR10 turntable was the cheap way to get a top line system.
What I think did it in was the increase in popularity of moving coil cartridges. The combination did not work well with the first ones easily available.
For a bit of interest I haven't seen a used one pop up locally. Hundreds were sold here.
My two cents. I don't own analog. However, the finest system I have ever experience was vinyl. The entire system was of a pedigree I will never own, from a $5K hand-made French cartridge to finessed room treatment in a nearly perfect room, and everything in between considered and optimized. It was the only system I have ever experienced that went way beyond absolutely reproducing the three dimensional space, into a profound reproduction of emotion. There was such a huge transfer of emotion from the performer to us the listeners, that we walked away astounded that that level of information could be captured (not to mention reproduced). It was not a distortion, it was extreme high end sound reproduction. The surface noise of the disc was removed from the music by its existing in a space that was not in the recreated space the performers occupied. Some people may prefer vinyl because at its finest, it can approach magic. Thanks.I firmly believe that this right here is the crux of the biscuit, as Frank used to say. I think that people are affected just as much by the various imperfections in audio reproduction as by the "good" sounds (and sights, and smells).
I grew up listening to vinyl, and was always so frustrated by pops & ticks, cartridge mistracking, inner groove distortions, etc, etc, that I eventually gave up even trying to enjoy some of the more challenging recordings (piano, organ orchestral, etc.) Digital audio (yes, even redbook CD) has allowed me to enjoy these recordings again.
And yet there are plenty of intelligent, open-minded people who absolutely prefer the sound of vinyl, and complain of digital's harshness or sterility or any number of things. The only plausible explanation for this I've been able to come up with is that each group is hearing something(s) objectionable in one medium or the other, that the other group either doesn't notice or isn't bothered by (as much).
For whatever reasons, be they physiological, psychological, political or spiritual, people just hear stuff differently. And that includes the stuff we don't like.
-- Jim
Marsupialx
Here are some results from behind the scenes.
Firstly: the problem that whatever the slope of the filter, the slope of the anti-phase rolloff is always 6dB/oct with an unwanted 2dB peak as rolloff starts. This is a well-known effect exhibited by subtractive crossovers, and is due to the phase-shift in the filter preventing proper cancellation. See
http://www.douglas-self.com/ampins/books/crossover%20book.htm Chapter 6
This problem was addressed by Lipshitz & Vanderkooy who showed that if you put a suitable time-delay in the unfiltered path, you get the same slope as the filter.
3] Lipshitz & Vanderkooy "A Family of Linear-Phase Crossover Networks of High Slope Derived by Time Delay" JAES Vol 31 Jan/Feb 1983, p2
The circuit I used for these tests is a development of the Langvad configuration, with a 2nd-order lowpass filter and time correction by allpass filters.
This is the antiphase response with no time correction. Note 6dB/oct slope and +2dB peak. The dotted line is at -3 dB.
This has optimal time correction for maximum rolloff slope. the response is -41dB at 10Hz, which ought to do the job.
This shows the intriguing result of increasing the time correction by a mere 1%. There is a nice little dip pretty much where we would like it. Further increases in time correction move the dip up in frequency and spoil the slope so this does not look like a good way to go.
I'm still working on the circuit design, but as mentioned well upthread, I have made it work with a 24 dB/oct rolloff slope. The filter was a 4th-order Linkwitz-Riley, ie two 2nd-order Butterworths cascaded.
Firstly: the problem that whatever the slope of the filter, the slope of the anti-phase rolloff is always 6dB/oct with an unwanted 2dB peak as rolloff starts. This is a well-known effect exhibited by subtractive crossovers, and is due to the phase-shift in the filter preventing proper cancellation. See
http://www.douglas-self.com/ampins/books/crossover%20book.htm Chapter 6
This problem was addressed by Lipshitz & Vanderkooy who showed that if you put a suitable time-delay in the unfiltered path, you get the same slope as the filter.
3] Lipshitz & Vanderkooy "A Family of Linear-Phase Crossover Networks of High Slope Derived by Time Delay" JAES Vol 31 Jan/Feb 1983, p2
The circuit I used for these tests is a development of the Langvad configuration, with a 2nd-order lowpass filter and time correction by allpass filters.
This is the antiphase response with no time correction. Note 6dB/oct slope and +2dB peak. The dotted line is at -3 dB.
An externally hosted image should be here but it was not working when we last tested it.
This has optimal time correction for maximum rolloff slope. the response is -41dB at 10Hz, which ought to do the job.
An externally hosted image should be here but it was not working when we last tested it.
This shows the intriguing result of increasing the time correction by a mere 1%. There is a nice little dip pretty much where we would like it. Further increases in time correction move the dip up in frequency and spoil the slope so this does not look like a good way to go.
An externally hosted image should be here but it was not working when we last tested it.
I'm still working on the circuit design, but as mentioned well upthread, I have made it work with a 24 dB/oct rolloff slope. The filter was a 4th-order Linkwitz-Riley, ie two 2nd-order Butterworths cascaded.
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Ah, I remember that one now. Presumably its effective mass was lower than the Dynavector.
Sigh.... I did both of these a few days back and talked about it here. No one seemed to notice.
Funny that even tho this forum is a digital format, a lot of info gets lost in the noise.
I'll being doing some more of this today, now that I'm home from the road. Will post further results.
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