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Orsefon C22 (McIntosh C-22 circuit copy)

CohibaJoe

CohibaJoe

AK Subscriber
Subscriber
So here we are again:naughty: now with a Clone/Copy Mac C22 circuit...Orsefon C22. This will be used with
the Orsefon MC275 Amp that's been sounding really good. Will burn in (200hrs) with Luxman M-4000 and a Tube swap at 100hrs. Still deciding on a Tube set and will be using the included (Orsefon 12AU7, 12AX7). Frist off this Pre-Amp is Dead quiet and the Orsefon tubes are sounding good.

4 12AT7 for MM/MC Phono Amp
2 12AX7 Pre-Amp

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MM/MC Phono Boards
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Just curious - do you have any local audio people with either Mcintosh MC275 or C22’s to be able to do a side by side comparison?

Longshot, but it would be very interesting esp if the tubes were the same.
 
Hello! I have one of these as well. The MM and MC inputs were an added cost on mine and it looks identical to the one you have posted. Mine has a problem of very noisy MM and especially MC inputs. The MC input is dead quiet with nothing plugged in, and dead quiet with a turntable connected with no cartridge installed. Pop the cartridge in and radio noise and heavy dark sounds make for a very grim background to any music. The other inputs are dead quiet and the unit sounds very good to me. The seller has not been terribly helpful but I think the issue is mainly language. Any thoughts would be appreciated!
 
Steve Hynes said:
Hello! I have one of these as well. The MM and MC inputs were an added cost on mine and it looks identical to the one you have posted. Mine has a problem of very noisy MM and especially MC inputs. The MC input is dead quiet with nothing plugged in, and dead quiet with a turntable connected with no cartridge installed. Pop the cartridge in and radio noise and heavy dark sounds make for a very grim background to any music. The other inputs are dead quiet and the unit sounds very good to me. The seller has not been terribly helpful but I think the issue is mainly language. Any thoughts would be appreciated!
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I have not used the Built-In Phono inputs and will hookup a TT later today. I have picked up Upgraded parts (replace WIMA and MM/MC Opamps) that I will be posting later next week.
 
Steve Hynes said:
Hello! I have one of these as well. The MM and MC inputs were an added cost on mine and it looks identical to the one you have posted. Mine has a problem of very noisy MM and especially MC inputs. The MC input is dead quiet with nothing plugged in, and dead quiet with a turntable connected with no cartridge installed. Pop the cartridge in and radio noise and heavy dark sounds make for a very grim background to any music. The other inputs are dead quiet and the unit sounds very good to me. The seller has not been terribly helpful but I think the issue is mainly language. Any thoughts would be appreciated!
Click to expand...

gadget73 said:
honestly kind of sounds like a configuration problem with the turntable. If the preamp were the issue I'd expect it to be noisy with nothing plugged in. Maybe its got a ground loop going on for some reason.
Click to expand...

I would definitely look at the turntable's grounding...sounds like you describe are coming from the turntable/cartridge...

What kind of table/arm?

Or, do you live in a high RF area?
.
 
Thank you for your replies!

I have tried two turntables as well as a bare tonearm. All produce very loud buzzing and radio interference, except when the contacts are open (as in no cartridge connected). The buzz and interference also happens when the leads are shorted. The tables both work fine on other equipment. I have done everything to isolate a grounding problem. Nothing helps. I have pulled and shuffled the opamps, things change a bit but nothing much improved. My seller on Aliexpress is unhelpful, despite my sending a clear video showing the problem, an infinite loop of ask for help/contact “engineer”/please check your turntable. I have asked for schematics but the request has been ignored. This is really too bad as otherwise this seems like a good unit.

Any ideas would be appreciated!
 
What arm, cartridge,and table?

I've had issues with specific all-metal cartridges on my Thorens. Thorens uses one of the signal leads to ground the chassis rather than the flying lead that many use. All-metal cartridges that are not mounted with any bushings or insulation washers (like the Stanton 681 and the Shure M93E that I run) have a ground strap from one of the cartridge pins to the body. If I don't pull that strap it creates a ground loop and it hums. Carts with plastic mounting ears are no issue. No clue if thats the same type of situation you are dealing with but it might be worth an ohm check from the arm or headshell to turntable chassis to see if it is grounded, and from headshell to leads to verify no connection if you have a ground lead. Basically the arm can't be grounded in 2 places or its going to act dumb.
 
The 8 pin chips are op amps. I am using a Linn LP12, Ekos, Troika, as well as an Oracle Premiere, SME V, Koetsu - also a Grade Signature tonearm with a Denon MC, not mounted to anything to check. Same behaviour with all of it. All works perfectly with a Krell KRS preamp, Audio Research preamp, and Luxman C-05 and some others. The reason I did not mention any of this is that the same thing happens when you short circuit the tonearm leads (or any cable) plugged into the MC input, so it seems like its really a fault in the preamp. The MC input is dead quiet with nothing plugged in. Too quiet in my opinion.

CohibaJoe - have you used the mm/mc inputs on your unit yet?
 
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Sounds like something is FUBARed in the phono boards, maybe a bad grounding scheme or something unconnected...so they do amplify what is fed them...there's just got to be something wrong in the grounding/shielding of the preamp to my way of thinking.
 
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