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How to calculate resistance for a sub woofer

My 55 year old McIntosh MC-225 has speaker connections for 4, 8, or 16 Ohms. I use the standard speaker connections to connect to a Acoustech PL-200 subwoofer, which has in impedance of 8 Ohm. The PL-200 is connected to Focal 807v’s which are also 8 Ohm.
So what output should I use on the MC-225? I don’t know if the PL-200 connects to speakers in series or parallel (and the Acoustech support page doesn’t seem to work). Is there a standard way sub woofers work that I should assume?
I was using the 8 Ohm, but the amp died! Don’t know if this is related.
tommaster
noromance's avatar
noromance
9,771 posts
 
I was using the 8 Ohm, but the amp died! Don’t know if this is related.
Is this sorted?
Connect this way:
Amplifier speaker out (- / + 8 ohm) > sub high-level inputs. (In parallel with your standard speaker connections.)
fuzztone's avatar
fuzztone
5,604 posts
 
What millercarbon said.
Don' worry 'bout it.
tommaster OP
10 posts
 
Thank you all!
edgewound
259 posts
 
Are you using 2 subs or just one?

My preference would be to drive the subs with line level from the preamp. That way, the sub is electrically isolated from the MC-225. If the PL-200 develops any issues, it can send a dead short to the amp. Not good.
oldhvymec
5,101 posts
 
First things first. Did you rebuild the power supply or not. IF you didn't STOP. Rebuild the power supply before you wipe out a transformer..

IF it's a fuse good if not... Hmmmm!! That ain't good on a 225.. Just to let you know. You HAVE TOO repair the power supply, if you don't BINGO! 200.00 at the most for all the caps and rebuild parts for the PS...Complete all new BB Cap replacement another 125 or so.

I have a 225 that is as PERFECT as any I've EVER seen...Truly museum quality.. Even the original RCA BP Mcintosh driver tubes, YUP..

Regards
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