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Old 17th November 2009, 12:47 PM   #81
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Hi Russ,

Thanks for the reply. I was also thinking in that way.

Best regards,
Bins.
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Old 18th November 2009, 01:00 AM   #82
PJN is offline PJN  United States
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Hi Russ,

It's about time, a phone stage is just what I've been looking for so I can play my LP collection through my RevC. If retro is anything like the rest of your products it should be great. You can count me in for a kit when they're ready.

PJN
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Old 18th November 2009, 03:56 AM   #83
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Exclamation Using RETRO with Ortofon 2M Red.

Hi Russ,

I am planning to use the circuit posted on #21 with my Ortofon 2M Red MM cartridge (2M Red). The recommended load resistance is: 47K and the recommended load capacitance is 150-300 pF. What all components should be modified in the original schematic for making it suitable for that cartridge ? Please advice.

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Old 18th November 2009, 04:07 AM   #84
ichiban is offline ichiban  United States
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Quote:
Originally Posted by binspaul View Post
Hi Russ,

I am planning to use the circuit posted on #21 with my Ortofon 2M Red MM cartridge . The recommended load resistance is: 47K and the recommended load capacitance is 150-300 pF.

Load is already 47k, R7 & R8. Caps C3 & C4 are 22pF, change them to 150-300pF.

Edit: I see the schema in post #21 does not show those resistors, they would be parallel with c3 & c4 which are after the 100R input resistors.
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Old 18th November 2009, 07:00 AM   #85
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Hi,

Thanks for your suggestion. It is shown in the Retro High Z schematic diagram that is available in the subsequent post.

Best regards,
Bins.
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Old 18th November 2009, 05:28 PM   #86
BrianL is offline BrianL  United States
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Remember that the capacitive loading the cartridge sees consists of ALL capacitances: capacitance in the tonearm wires, capacitance in the cable from tonearm to preamp, input capacitance in any preamp wiring between chassis jack and PCB, any specific capacitor across the preamp input.

Something I didn't notice before. The schematic attached to post 55 (Hi-Z MM version) actually loads the cartridge with 94K Ohms (from IN/OUT.1 to IN/OUT.6), not 47K Ohms. More precisely, 94K + 442 Ohms. This should be fixed...

Back to the capacitance. Before picking a loading cap to put on the PCB, you need to know the capacitance of the other portions of the system. If you're lucky, the maker of your tonearm will tell you the values of capacitance in the tonearm and/or interconnect. If not, you need to measure them.

MC cartridges are much lower impedance so the capacitive loading is less of an issue, but MMs are more critical.

Note also that whatever value you decide you need on the PCB, the values for C3 and C4 need to be double that because they are in series.
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Old 1st December 2009, 03:17 AM   #87
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Hi Brian, You are correct about the loading and the series caps. I have corrected that.

Cheers!
Russ
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Old 11th December 2009, 01:53 AM   #88
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Default Retro

Hi Russ,
I would be interested in a Retro to use with my Soundsmith retipped Denon DL-103 LOMC. I think I sent a pm but the site may have logged me out first. LMK Thanks, Jeff
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Old 12th December 2009, 01:19 AM   #89
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Quote:
Soundsmith retipped Denon DL-103 LOMC
The one with the ruby cantilever? We had this one running in our ETF setup (stripped and mounted in a wooden body). Very nice cartridge.
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Old 12th December 2009, 01:27 AM   #90
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Moin Holgi,
nice 2 meet u in the badlands.
Would u like 2 tell more about this
thingie ?
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