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PostPosted: Wed Dec 13, 2017 11:37 am 
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Hey all,

I recently bought a Goldring 1006 MM cartridge for my turntable. Its recommended load capacitance is 150-200pf.

On my current phono pre (ART USB phono plus) impedance is fixed at 100pf. I have a rather long run of cable (12') from there to my amp, using BJC low capacitance cable, rated at 12.2 pf/foot. If I total up the values all along, I'm currently running at about 250pf, plus whatever is added by the tonearm cables.

Question is, should this concern me? Is it OK to run the goldring at ~250pf or more, and what kind of difference might it make? Should I try to get down to recommended levels?


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PostPosted: Wed Dec 13, 2017 11:47 am 
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Load capacitance is just an recommendation – it does not have to be followed as shown by the many phono preamps that do not allow this to be adjusted. But just for clarification, is the long run between your turntable and phono pre, or between your phono pre and amplifier? Given the sensitivity of a phono signal (between turntable and phono pre), shorter runs would be preferred. Again, just a recommendation :wink:


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PostPosted: Wed Dec 13, 2017 11:51 am 
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Thanks @sthomas1049, that was my sense. I guess I'm curious what kind of effect the extra load might have?

The long run is between the phono pre-amp and the amp. :)


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PostPosted: Wed Dec 13, 2017 12:06 pm 
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Hi,

My recollection is that variations in the capacitive loading of a MM cartridge primarily influences the shape of a cartridge's response curve at higher frequencies, say those above 10K Hz and out to the upper limits of the cartridge's response. As noted above, cartridge loading level is a recommendation, not an absolute. An extra 50 picofarads, as in your case, is a trivial amount and is unlikely to make any audible difference. A change from say 200 to 400 pf might be detectable, if your hearing is still quite sharp. It is also worth noting that the phono stage performs an inversion of the RIAA curve, since the signal on the record is RIAA enhanced and this inversion process also may or may not add both high and low frequency emphases, and depends on the quality of the phono stage and it's interaction with the cartridge signal.

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David Neice

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PostPosted: Wed Dec 13, 2017 12:10 pm 
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two2the8 wrote:
Thanks @sthomas1049, that was my sense. I guess I'm curious what kind of effect the extra load might have?

The long run is between the phono pre-amp and the amp. :)


In a nut shell - Recommended load capacitance just ensures you are getting the flattest frequency response as per the cartridge manufacture. It is more of a preferred setting should it be available and changes could be subtle if anything at all.
The long run between phono pre and amplifier should not be of concern for the capacitance they speak of is between your cartridge and phono pre which also included the capacitance of your tonearm wire.

Use to have a link that when into detail on cartridge loading but can’t seem to find it. If I come across it I will post it. or you could just read buybye88 post....well said!


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PostPosted: Wed Dec 13, 2017 12:27 pm 
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sthomas1049 wrote:
The long run between phono pre and amplifier should not be of concern for the capacitance they speak of is between your cartridge and phono pre which also included the capacitance of your tonearm wire.


Ah, of course, that makes a lot of sense.

I think I'm more or less in the ballpark, then, maybe even a little under the manufacturer's recommendation. Sounds like it's not a big deal either way. One day I'll get a better phono pre with some adjustments, and I guess I'll try out some different settings and see what happens. Thanks all!


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PostPosted: Wed Dec 13, 2017 1:03 pm 
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AAron, let us know how the new cart works out. I hope you have a great Christmas spinning wax!! :D


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PostPosted: Wed Dec 13, 2017 1:11 pm 
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Thanks Tom! I've got a bit of work to do over the holidays installing a new arm & getting the new cartridge set up, but I'm looking forward to it. I'll letcha know how it all goes :)

Happy holidays all.


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PostPosted: Wed Dec 13, 2017 1:50 pm 
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Your tonearm wiring capacitance is probably on the order of 150uF. Add the 12.2 x6 or 8 which equals ~100 (frankly that's a lot lower than most), plus the 100 for your phono pre and you have about 300 or more, probably 350uF. that's heading into old school Shure requirements. Most dedicated audio people today have very little experience with the characteristics of MM cartridges,preferring the ubiquitous MCs. However, to get the best out of MMs........... follow the recommendations. I'd shorten the cable to your pre down to at most 3.5 or 4 feet............ just because of capacitance only. Almost all of my better vintage gear allows me to adjust loading, and in some cases where the manufacturer didn't, there were instructions how to modify.

I just checked one of my pre calculation manuals and the recommendation was to stay at +- 15% of recommendation.

If you believe the cable difference crowd, you'd be hard pressed to argue that capacitance differences are subtle at best! :D

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PostPosted: Wed Dec 13, 2017 1:59 pm 
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Tonearm cable capacitances on modern decks are generally lower than they used to be so whether what you have is acceptable would really depend on the vintage, and the length of the cable.

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PostPosted: Wed Dec 13, 2017 2:15 pm 
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Thanks all. I think sthomas1049 cleared up the question considerably, noting that the long run I'm talking about happens *after* the phono preamp, not before, so the load I specified earlier is probably way incorrect.

I'm mounting the cartridge in a RB250 tonearm with TFA rewire. I'm not sure the spec of the rewired cables (they're an older version), but the current TFA cables are measured at around 32pf. I'd guess that the older version has a bit higher capacitance, but I don't really know.

Anyway, taking @davinci_redux' estimate of 150 (pf or uf?) for an average cable, I'd guess my cables are in the range of 32-150. Add the 100 from the phono preamp, and that looks to total somewhere between 132-250. Chances seem pretty good that the values will fall within the 150-200 range, or at least close enough (+/- ~25%) to make a negligible difference. Sound right?


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PostPosted: Wed Dec 13, 2017 3:01 pm 
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two2the8 wrote:
Thanks all. I think sthomas1049 cleared up the question considerably, noting that the long run I'm talking about happens *after* the phono preamp, not before, so the load I specified earlier is probably way incorrect.

I'm mounting the cartridge in a RB250 tonearm with TFA rewire. I'm not sure the spec of the rewired cables (they're an older version), but the current TFA cables are measured at around 32pf. I'd guess that the older version has a bit higher capacitance, but I don't really know.

Anyway, taking @davinci_redux' estimate of 150 (pf or uf?) for an average cable, I'd guess my cables are in the range of 32-150. Add the 100 from the phono preamp, and that looks to total somewhere between 132-250. Chances seem pretty good that the values will fall within the 150-200 range, or at least close enough (+/- ~25%) to make a negligible difference. Sound right?


In one word, Yup! :)


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PostPosted: Wed Dec 13, 2017 4:07 pm 
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Hi,

Sounds good. And now over to the caviar. Do you have a detachable phono interconnect cable on your TT or is there a removable phono cable plug nestled into the arm pillar? If yes, then have a look at this thread.

viewtopic.php?f=32&t=48150

Cheers,
David Neice

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PostPosted: Wed Dec 13, 2017 4:45 pm 
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I could be wrong but I don’t think the purpose of CAM is to push a particular product.

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