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#1
Posted to rec.audio.tech
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Phono loading and MM vs MC
Recently there has been some discussion on usenet of the relative
sensitivity to loading of MM and MC cartridges. I learned this from early issues of the IAR published back in the late '70's early '80s and have used the knowledge ever since. The following is a link to audioasylum, to a post that shows the effects of loading and phase on a late model Shure V15 and an Audio Technica OC-9. It is very illustrative of the advantages of a properly loaded MC, and why it is possible to get them to sound (and be) perfectly flat. Since 1990 my test has been...can I get the cartridge to sound as flat as a CD of the same material. Once this is achieved, then some other benefits of cartridges can come to the fore. Thought many would find this interesting who don't vist Audio Asylum very much. http://www.audioasylum.com/audio/vin...es/597184.html |
#2
Posted to rec.audio.tech
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Phono loading and MM vs MC
"Harry Lavo" wrote in message . .. Since 1990 my test has been...can I get the cartridge to sound as flat as a CD of the same material. Let us know if you ever succeed :-) MrT. |
#3
Posted to rec.audio.tech
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Phono loading and MM vs MC
"Mr.T" MrT@home wrote in message u... "Harry Lavo" wrote in message . .. Since 1990 my test has been...can I get the cartridge to sound as flat as a CD of the same material. Let us know if you ever succeed :-) MrT. Have, since 1990. :-) |
#4
Posted to rec.audio.tech
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Phono loading and MM vs MC
Harry Lavo wrote:
Recently there has been some discussion on usenet of the relative sensitivity to loading of MM and MC cartridges. I learned this from early issues of the IAR published back in the late '70's early '80s and have used the knowledge ever since. The following is a link to audioasylum, to a post that shows the effects of loading and phase on a late model Shure V15 and an Audio Technica OC-9. It is very illustrative of the advantages of a properly loaded MC, and why it is possible to get them to sound (and be) perfectly flat. Since 1990 my test has been...can I get the cartridge to sound as flat as a CD of the same material. Once this is achieved, then some other benefits of cartridges can come to the fore. Thought many would find this interesting who don't vist Audio Asylum very much. http://www.audioasylum.com/audio/vin...es/597184.html Very interesting, and thanks for the post. However, if I have understood the graphs correctly, the MC graph shows no effect on frequency response until well into rf. At af, it would seem that the response is identical whatever the load. As it happens, I have now changed my two MM cartridges for low output MCs, but run them both into 47k inputs perfectly happily. As there is low coupling between the mechanical and electrical parts of the cartridge, it seems to me that running into a low impedance, (say 100 ohms or less) won't make any significant difference to damping the tip/vinyl resonance. That being so, what other benefit is there from a low impedance? I would expect the distortion to be lower if the cartridge isn't being asked to drive any current, although even here I would not expect a noticeable improvement. S. |
#5
Posted to rec.audio.tech
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Phono loading and MM vs MC
"Serge Auckland" wrote in message ... Harry Lavo wrote: Recently there has been some discussion on usenet of the relative sensitivity to loading of MM and MC cartridges. I learned this from early issues of the IAR published back in the late '70's early '80s and have used the knowledge ever since. The following is a link to audioasylum, to a post that shows the effects of loading and phase on a late model Shure V15 and an Audio Technica OC-9. It is very illustrative of the advantages of a properly loaded MC, and why it is possible to get them to sound (and be) perfectly flat. Since 1990 my test has been...can I get the cartridge to sound as flat as a CD of the same material. Once this is achieved, then some other benefits of cartridges can come to the fore. Thought many would find this interesting who don't vist Audio Asylum very much. http://www.audioasylum.com/audio/vin...es/597184.html Very interesting, and thanks for the post. However, if I have understood the graphs correctly, the MC graph shows no effect on frequency response until well into rf. At af, it would seem that the response is identical whatever the load. As it happens, I have now changed my two MM cartridges for low output MCs, but run them both into 47k inputs perfectly happily. As there is low coupling between the mechanical and electrical parts of the cartridge, it seems to me that running into a low impedance, (say 100 ohms or less) won't make any significant difference to damping the tip/vinyl resonance. That being so, what other benefit is there from a low impedance? I would expect the distortion to be lower if the cartridge isn't being asked to drive any current, although even here I would not expect a noticeable improvement. The resistance does affect whether or not the extended frequency response slopes upward, downward, or remains flat. And the capacitance acts as a "trim". At least over a broad range of mc's, that's what appeared to be the case in IAR's work. In my own case, I once owned a Counterpoint SA-2 that was completely adjustable in loading. I followed the dealer/manufactures recommended load of 57ohms on my Accuphase AC-2. Believe it or not, a change to 85ohms in that machine made a fairly substantial difference. With this loading, the AC-2 in a Syrinx arm on a Linn sounded identical to my Phillips 880 top-of-the-line CD player....except their was more air behind and dimensionality in the imaging of individual voices and instruments. I've also experimented with an adjustable AA Vac-in-the-box, and several mcs (dynavector, accuphase, alchemist, etc.) and found loading combinations made a sizeable difference, particularly as you get down to 100 ohms and below. I still own and use an Accuphase AC-2 (one of several) which was TAS's prize MC for a year or so early '80's. HP ran it into 47,000 ohms. When I do that, I can't listen. Sounds thin and "etched" to me. I believe the ultrasonic peak screws up the transient response, and I seem particularly sensitive to this aspect of audio reproduction. With transformers, you have to match the output impedance of the cartridge. With headamps or phono preamps, the design of the preamp as well as the loading values seem to come into play...I currently use that same cartridge through a modified Marcof PPA-2 battery-powered headamp, and it is as flat as the Counterpoint was at 57 ohms. With most mc's, loading at or below 100 ohms seems to flesh out the midrange and smooth out high-frequency transients to the point of sounding "natural". But once you get in the ballpark, some experimentation is in order. |
#6
Posted to rec.audio.tech
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Phono loading and MM vs MC
"Harry Lavo" wrote in message
"Mr.T" MrT@home wrote in message u... "Harry Lavo" wrote in message . .. Since 1990 my test has been...can I get the cartridge to sound as flat as a CD of the same material. Let us know if you ever succeed :-) MrT. Have, since 1990. :-) Show us the FR curves. ;-) |
#7
Posted to rec.audio.tech
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Phono loading and MM vs MC
Serge Auckland wrote: Very interesting, and thanks for the post. However, if I have understood the graphs correctly, the MC graph shows no effect on frequency response until well into rf. At af, it would seem that the response is identical whatever the load. I'm not sure why anyone would find this at all surprising. Fact is, the effective source impedance of most moving coil cartridges is several orders of magnitude lower than most moving magnet cartridges, Thus, for the same reactive loading (effectively a parallel combination of a shunt capacitance but an appropriate load resistance), the effects should be correspondingly higher in frequency. |
#8
Posted to rec.audio.tech
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Phono loading and MM vs MC
"Harry Lavo" wrote in message . .. Since 1990 my test has been...can I get the cartridge to sound as flat as a CDof the same material. Let us know if you ever succeed :-) Have, since 1990. :-) But unfortunately cannot prove it with actual measurement right? :-) MrT. |
#9
Posted to rec.audio.tech
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Phono loading and MM vs MC
"Mr.T" MrT@home wrote in message
u "Harry Lavo" wrote in message . .. Since 1990 my test has been...can I get the cartridge to sound as flat as a CDof the same material. Let us know if you ever succeed :-) Have, since 1990. :-) But unfortunately cannot prove it with actual measurement right? :-) Nor with a reliable, bias-controlled listening tests. Harry just asserts based on so-called evidence that is known to be highly unreliable. |
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