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Mc225 to c27 stereo wiring help

Alfmonster

Alfmonster

Active Member
Hello AK!

I’ve recently changed my speaker wiring setup to go from the mc225 amp to the c27 preamp so I could use the headphone output.

I’m reaching out to the AK community to see if maybe someone has experience with biwiring to the speakers directly from the preamp — and perhaps would be kind enough to share some advice to help.

Also, when wiring directly from the amp to the preamp - do you use the ohm that your speaker needs or do you go higher? (My speakers require 8ohms).

Thanks so much I’m advance!!


Edit: gear — thanks @Pio1980
 
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Electrically there's no difference between bi-wiring and single wiring. In effect all that's being done is moving the jumpers from the speakers to an extra wire from the amplifier. In any case, connections to the amplifier should be made at the same taps as the speaker is rated since the effective load would be no different using bi-wiring.

Keep in mind that since the MC225 is a tube unit, it should not be run without a load connected - either from the headphone jack or the speakers. The C24 & C26 were equipped with circuitry to maintain a load on the amplifier in the event the speakers be shut off from the front panel switch without headphones connected but it doesn't appear the C27 is designed with this provision.
 
62caddy said:
Electrically there's no difference between bi-wiring and single wiring. In effect all that's being done is moving the jumpers from the speakers to an extra wire from the amplifier. In any case, connections to the amplifier should be made at the same taps as the speaker is rated since the effective load would be no different using bi-wiring.

Keep in mind that since the MC225 is a tube unit, it should not be run without a load connected - either from the headphone jack or the speakers. The C24 & C26 were equipped with circuitry to maintain a load on the amplifier in the event the speakers be shut off from the front panel switch without headphones connected but it doesn't appear the C27 is designed with this provision.
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Thank you for replying! Can you further explain about connecting a load to the mc225? I have the speaker wire going from the 8ohm post to the back of the preamp. And also an rca from the preamp to the amp. Is there something else I should wire? Also curious, what would happen to the amp if a load is not connected to it?

I’m a bit confused (and concerned that I may have already ruined the amp) by this part - thanks again for your reply -this is very helpful information! @62caddy
 
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Alfmonster said:
Thank you for replying! Can you further explain about connecting a load to the mc225? I have the speaker wire going from the 8ohm post to the back of the preamp. And also an rca from the preamp to the amp. Is there something else I should wire? Also curious, what would happen to the amp if a load is not connected to it?

I’m a bit confused (and concerned that I may have already ruined the amp) by this part - thanks again for your reply -this is very helpful information! @62caddy
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The connections you describe are correct if the speakers are 8 ohm. Just make sure the headphones are connected to the front panel before disconnecting the speakers, ie: shutting off by the front panel speaker switch(es).

I doubt any damage was caused to the amplifier if it's performing normally but running a tube amplifier without a load connected should be avoided. IF you are worried about this occurring, it might be advisable to connect a 100 ohm 1 watt resistor across the output terminals (COM and 8) of the amplifier. The output loss will be minimal and will protect the amplifier from oscillating.
 
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62caddy said:
The connections you describe are correct if the speakers are 8 ohm. Just make sure the headphones are connected to the front panel before disconnecting the speakers, ie: shutting off by the front panel speaker switch(es).

I doubt any damage was caused to the amplifier if it's performing normally but running a tube amplifier without a load connected should be avoided. IF you are worried about this occurring, it might be advisable to connect a 100 ohm 1 watt resistor across the output terminals (COM and 8) of the amplifier. The output loss will be minimal and will protect the from oscillating.
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Your explanation helps so much!

How do I connect the 100ohm 1 watt resister to the tap? Do I just screw the wire ends of the resister into both 8ohm/com post on both Right/Left with the speaker wires going to the preamp?

again thanks for taking the time to reply to me
 
with high powered sand gear (solid state - 300+ watt/chnl), you can sometimes hear a difference with bi-wiring and biamping. but with tubes have never heard much of a difference, even with high powered tube monoblocks.

I have several MC225s. and have tried running them in monoblock config, but much of the MAC MC225 magic is lost.

If it were me, would focus on spending the money on other areas, rather than a biwire speaker cable.

and don't run your MC225 without a load connected to it.
 
mcgjohn said:
with high powered sand gear (solid state - 300+ watt/chnl), you can sometimes hear a difference with bi-wiring and biamping. but with tubes have never heard much of a difference, even with high powered tube monoblocks.

I have several MC225s. and have tried running them in monoblock config, but much of the MAC MC225 magic is lost.

If it were me, would focus on spending the money on other areas, rather than a biwire speaker cable.

and don't run your MC225 without a load connected to it.
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Your advice along with @62caddy’s advice made me dig up the binding posts and change the speakers to single wiring to find you were both right about the biwiring not making any difference in my setup.

I’m really glad I found out about not running the amp without a load - bc in the past, I may have turned the amp on first to have it warm up before turning on my preamp. However, this was before I ran the speaker wires through my preamp...so perhaps I’m safe?

Thanks for taking the time to reply!
 
The speaker switching is passive therefore the speaker switches work the same whether the C27 is powered up or not.

I would simply plug the MC225 into one of the C27's switched outlets so that it will be powered up whenever the C27 is turned on.
 
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