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#1
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Why no 47k ohm setting on c500?
Any reason for nat having a “wide open” or 47k ohm as a selection for MM capacitance setting on the c500 preamp?
I ask because I want to run a low output MC cart (0.25 mV) through a Bob’s Devices step-up transformer into the MM stage. I believe these step-ups are designed to be run into a 47k ohm cap setting, but the c500 has an upper limit of 750 ohms. The cart is a Denon 103R. Yes, I know I can run it through the MC, and I have—but the gain was not enough...and I run a second MC cart (Lyra Titan i) through the MC stage as a primary. The step-up transformer does give the necessary gain (even on the “low” setting) needed for the MM stage, but it doesn’t have some of the low end snap I feel it should have, and the high end sounds restrained. Any suggestions? Any insight as to why Mac doesn’t offer a 47k ohm setting for MM? |
#2
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I believe that you are confusing capacitance for input impedance, which, according to the C500 owner's manual, is 47K ohms. Input impedance is expressed in ohms, while capacitance is expressed in pF.
As to why you're not getting what you are looking for, out of your step up transformer, your guess is as good as mine. I'm sure that somebody, a lot more knowledgeable than myself, will come along shortly to offer some insight. Good luck getting it sorted out. |
#3
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Spec's from the manual:
Input Impedance High Level: 22K ohms Phono: MM, 47K ohms; 50 to 750pF, in 50pF steps MC: 25, 50, 100, 200, 500 or 1,000 ohms; 100pF Setting the MC to 100 ohms is recommended by some reviewers for the Denon 103R The C500 MC phono stage has 60db of gain which should be enough. Check your input trim settings which can be adjusted +-6dB. Ron
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Ron Processor: McIntosh MX170, Amp: Legacy Audio i-V7, Digital: Benchmark DAC3B, Roon Music Player, Oppo UDP-205, Apple TV 4K, Fire TV Stick 4K Max, Analog: Gold Note Pianosa Turntable, Gold Note PH-10 Phono Preamplifier, Donatello MC Cartridge, Speakers: Legacy Audio Signature SE Natural Sapele Pommele, Silverscreen HD Center, JL Audio e112-Gloss Sub |
#4
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I run a Denon DL103 mc Cartridge which has .25mv output into my C2500 preamp at 100 ohms and I have plenty of volume. Putting the volume control at 45 is as loud as I would want it and it sounds really excellent. I had a Bobs Devices SUT with the red Cinemag transformers and tried it into the MM input, but liked the MC input without transformer better. It sounded more pure with more body and weight.
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#5
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It is in a second system where I am using Maggies, which are taking every last watt out of the amps—and I listen at high levels, so as I said before, the output is not high enough...and as stated above, I am using the MC stage for a Lyra cart.
The output is a good bit lower than any of the other 5 carts I use. I would like to use a 47k ohm load setting for the MM stage, but 750 ohm is the max. I have a few stand alone MM/MC phono stages that have a MM load setting option of 47k ohms, but the Mac doesn’t offer one...why not? |
#6
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Quote:
Phono: MM, 47K ohms; 50 to 750pF, in 50pF steps MC: 25, 50, 100, 200, 500 or 1,000 ohms; 100pF Ron
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Ron Processor: McIntosh MX170, Amp: Legacy Audio i-V7, Digital: Benchmark DAC3B, Roon Music Player, Oppo UDP-205, Apple TV 4K, Fire TV Stick 4K Max, Analog: Gold Note Pianosa Turntable, Gold Note PH-10 Phono Preamplifier, Donatello MC Cartridge, Speakers: Legacy Audio Signature SE Natural Sapele Pommele, Silverscreen HD Center, JL Audio e112-Gloss Sub |
#7
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Quote:
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#8
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I also found the Denon 103R to be best at 1000 ohms when using the MC stage...it just needs a bit of a bump in output.
Thanks for the replies. |
#9
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OK...I got it now.
So the MM stage is set to 47k with variable capacitance settings. That being the case, would changing capacitance setting among the 50pF to 750pF range alter the sound using a step-up with a MC cart? Is there a better setting (mathematically speaking)? The carts internal impedance is 14ohm, and I am using a 20:1 ratio for the step-up. Thanks again for the replies—appreciate the help and explanations. |
#10
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Quote:
Likewise the cartridge will 'see' the capacitance of the preamp and cable combination reflected by the transformer. The resistance of the cartridge is so low that all the effects of the cable and preamp capacitance will be well above the audio frequency range. Mathematically use the lowest capacitance possible. But, hey, why not experiment to see which setting you like the best? Tom
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Main System: Amati Futura Mains Amati Homage VOX Center, Proac Response 1sc Rears, Three MC2301's for L,C,R MC 602 for the rears C 1100, MX 151, MCD 1100, MR 80 Nottingham Dais with Wave Mechanic Sumiko Palo Santos Presentation SurfacePro 3, RPi 4, ROON, WW Starlight Platinum USB, Schiit Yggdrasil, Benchmark DAC3 HGC MX 151, OppO BDP-95, JVC RS-500 DILA projector, 106" diagonal Stewart Luxus Screenwall Deluxe with Studiotek 130 G3 material. Lake House: Ohm F, MC 275V, C2300, MR 77, Rega P3 OnDeck: McIntosh MAC 4300v |
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