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#1
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MA6900 Phono Stage - what is the gain?
Hey All
Hoping someone might have the definite answer to this. I recently bought a new t/t with an MC cart. (Rega P8 w/ Apheta 3 cart, too good of a deal to say no to!). Of course the MA6900 has an MM phono stage. I'm looking at getting a step up transformer. Problem is, I'm having trouble matching specs since I can't find the gain of the MM phono stage. I did email McIntosh but it might take a while for them to get back to me and remembered there's a lot of knowledgeable members here who might know the answer as well. Eddie |
#2
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Eddie,
from the 6900 manual: Sensitivity Phono, 2.5mV for 2.5V rated output (0.5mV IHF) Power Amplifier Input, 2.5V for rated output Apheta 3: 0.350 mV 100 Ohm load. Gain needed: 2.5/.350= 7.14 OR (20 log10(2.5/.350)) = 17 dB Use a normal 10:1 ratio (20 dB) MC step up transformer unless you want to have a custom one built, which I think is unnecessary. The Apheta wants to see 100 ohms, so you'll want to load the transformer secondary with 100 * 10^2 = 10,000 ohms. The 6900 has an input impedance of 47 kOhms, so you'll need a 12.7 k 1% or 12 k 5% resistor so that in parallel with the 6900's input impedance you'll get 10k Ohm.
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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 |
#3
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Thank you for the fast response.
Having done a bit of research (googling + speaking with others) I decided a SUT isn't the best option for me so I'll be looking at an external phono stage to deal with MC cart situation. Still not heard back from McIntosh, which is fair enough, they likely have more important work to do, but it's a reminder that posting on here, will usually get you the details you need, faster! Eddie |
#4
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Quote:
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#5
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Good advice Stephen.
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