Holman, Dynamic Range Phono Preamplifiers, Audio July 1977.

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mediatechnology
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Holman, Dynamic Range Phono Preamplifiers, Audio July 1977.

Post by mediatechnology »

"Dynamic Range Requirements of Phonographic Preamplifiers," Tomlinson Holman, Audio, July 1977, page 72-79.
The curve in figure 1 then gives the sine-wave low-distortion power response of the cutterhead and cutting stylus, cartridge, preamplifier combination. That is, no single-frequency component of program material may exceed the limits for low reproduced distortion. But, because overload is a peak phenomenon for which all frequency components instantaneously add, the actual spectral output of the preamplifier must run substantially below the sine-wave limit line.
"Dynamic Range Requirements of Phonographic Preamplifiers," Tomlinson Holman, Audio, July 1977, page 72-79 article pdf: https://proaudiodesignforum.com/images/ ... y_1977.pdf

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Holman, Dynamic Range Requirements of Phonographic Preamplifiers Fig 1.
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Re: Holman, Dynamic Range Phono Preamplifiers, Audio July 19

Post by ricardo »

Thanks for this Wayne. It was my Bible for the performance requirements of Phono Preamps. I don't agree with everything he said but IMHO, the info there is nearly complete.

A couple of points from my small experience as a wannabe cartridge designer. Fig 1 shows 3 regions.

AMPLITUDE LIMITED
High compliance required but NEVER a problem for good cartridges from about Shure M44-7. In fact most High Trackability cartridges have too much compliance (see later)

VELOCITY LIMITED
Resistance in da little rubber bung that the cantilever sits in decides this. The numbers suggest this should be the main limitation in cartridges but actually my listening tests say otherwise. ie usually not audible or objectionable. Possibly cos the actual spl on eg the 105cm/s Woody Herman track, is so high that speaker & other distortions (including the human ear) dominate.

ACCELERATION/GEOMETRY LIMITED
Stylus shape & tip mass sets this. The 'ss' becoming 'tush' is an accurate description of lesser cartridges and easy to pick up in listening tests. A non-intuitive point is that the compliance resonates with the tip mass, usually within the audio band so a lower compliance often helps trackability.

So too high a compliance can lead to worst results.

The article also shows the need for substantial subsonic filtering.

Finally, what the article doesn't look at is the effects of ticks & pops which often give transients well above Fig 1. One of Otala's students looked at this in an excellent AES paper at Hamburg 1981 (??) trying to find his zillion V/us slews. Instead the young man proved that Otala's zillion V/us didn't exist.

The overload behaviour of the 'OPA' is important here. TL07x is poor while 553x is good. But even better is a Moving Coil pre-preamp that cleanly limits a bit above the Fig 1 limits and has instantaneous overload recovery.

Sheeesh! Am I trying to outgeek Wayne? :mrgreen: :geek: :ugeek:
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Re: Holman, Dynamic Range Phono Preamplifiers, Audio July 19

Post by JR. »

ricardo wrote:
One of Otala's students looked at this in an excellent AES paper at Hamburg 1981 (??) trying to find his zillion V/us slews. Instead the young man proved that Otala's zillion V/us didn't exist.
:oops: :oops: :oops:

Yup nature is funny that way, things with mass don't accelerate instantaneously.

I never signed on to the TIM, SID, party back in those days.

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Re: Holman, Dynamic Range Phono Preamplifiers, Audio July 19

Post by mediatechnology »

The article also shows the need for substantial subsonic filtering.
I agree with that.
The FM effect he describes made me think about warp being mostly mechanically vertical and electrically L-R or Side.
This goes back to an observation I made earlier...

On 'phones it seemed that simply steering warp to mono improved clarity because it was eliminating the "out-of-head" pressure differences.
The warp energy was there - it was just moved to a different place.
Maybe there was some FM, but on phones the FM component shouldn't be that audible because the displacements are small.

Holman's example however was with speakers having larger cone displacement.

On speakers, steering warp to mono improved clarity but I wasn't hearing out-of-head pressure differences either way.
Something about it just sounded better despite the warp still being there.

L-R warp reproduced on speakers would seem to have double the cone displacement - or double the FM deviation - than mono warp because the cones are moving in opposite directions.
I'm going to listen to this again to understand why moving the subsonic to mono sounds clearer than having it in Side.

For whatever reason simply steering warp to mono makes a big difference.
Is not the best solution though.
Substantial sub-sonic filtering of L/R seems better.

Even better than that IMHO is aggressively HP filtering Side since the warp energy seems to be concentrated in L-R and the musical energy - due to elliptic EQ and vertical crossover - isn't concentrated there.
By HP filtering Side (vertical) and leaving Mid (lateral) untouched the effects of the filter would seem to be less.
This is what our member Eric proposed some time ago.
The more I look at it the more it makes even more sense.
Finally, what the article doesn't look at is the effects of ticks & pops which often give transients well above Fig 1
Yeah, they sure do.
10 to 15 dB or more.
The amount of headroom required when recording flat is already a lot.
Add a click on top of that and it's easily capable of hitting the guardrails.
How clipped clicks affect de-clicking is something I haven't tried but on my flat test transfers I was conservative to not to clip them.

I was glad I found this article.
I didn't save all my old back issues of Audio but I must have kept it for this one article.
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Re: Holman, Dynamic Range Phono Preamplifiers, Audio July 19

Post by emrr »

Great reference, I've never seen anything in depth on the subject.
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Re: Holman, Dynamic Range Phono Preamplifiers, Audio July 19

Post by Gold »

ricardo wrote: In fact most High Trackability cartridges have too much compliance (see later)

A non-intuitive point is that the compliance resonates with the tip mass, usually within the audio band so a lower compliance often helps trackability.
I'm glad to see this in print. I have come to the same conclusion. I am eternally on the quest for the perfect QC cartridge for cuts. I need a cartridge that is "typical" but also sounds good. It can't track too well or badly and it can't trace too well or badly either. Currently I'm using a Denon 103. For some reason I always like a conical stylus better than an elliptical even though they are higher distortion. I haven't been able to figure that one out yet.
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Re: Holman, Dynamic Range Phono Preamplifiers, Audio July 19

Post by ricardo »

Gold wrote:Currently I'm using a Denon 103. For some reason I always like a conical stylus better than an elliptical even though they are higher distortion. I haven't been able to figure that one out yet.
John (later Jean) Walton did a lot of work on this and concluded that tip mass was at least as important as stylus shape for HF distortion.

Vinyl reacts with tip mass & stylus shape in a very complex manner

He designed the Decca Deram, an inexpensive ceramic cartridge with, at the time, the lowest tip mass on a commercial cartridge. Also that tip mass was the biggest factor in record wear and a playing weight of 2.5gm was good for indefinite record life with conical 0.5 if tip mass was small.

It was only until Shure V15 (type I) that the fancy elliptical tips had comparable tip mass to Deram and could show their true advantage.

Denon 103 is in some ways, a slightly more expensive Decca Deram :D
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