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Speaker terminal polarity

I just unpacked my Cary 300B-SE mono blocks after being in storage for over 15 years.  Both speaker outputs (on each amp) look identical (not color coded) and neither is labeled + or -. I tried a continuity test against the amp chassis and both terminals read the same. How do I determine + from -?  Does it matter as long as I have each amp wired to its corresponding speaker the same way?

I must have asked this question when I got the amps 17 years ago, but can't locate the thread.  Standing by with red and black sharpie pens if necessary.

jamesddurkin
12 responses Add your response
p05129
501 posts
 
MC to the rescue again with wrong info. If you don’t know which terminals are plus and minus on the amp and you are using 2 speakers, you have a chance of reversed polarity of 1 of the speakers and this will cause a significant effect. 
You can’t assume by looking at your amp that the positive terminal is going to be at the same place on the opposite side of the amp. Call Cary or look for your amp online to see which terminals are positive and negative.
barryaudiophile
57 posts
 
Your question about absolute polarity is important.  In an ideal world a recorded kick drum when hit will cause the air to move toward the listener.  This will happen if phase integrity is maintained throughout the audio chain.  The audible effect is call the Wood Effect. Look it up on google.
jimofmaine's avatar
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jimofmaine
41 posts
 
I'd suggest to judge correct polarity by ear. Do a simple listening test: 1) connect your speakers up to your amp. Play a track with vocals. 2) Then ON ONE SPEAKER only, switch the positive and negative wires and listen again. The wire orientation that sounds the most focused, voice in between your two speakers, is the correct polarity, regardless of what colors or what you think is +, -.

ecscott482's avatar
ecscott482
44 posts
 
Place a 1.5 volt battery across the speaker inputs. 
If the speaker cone moves out, label the positive battery side connected to the speaker +   

If it move in, then label it - 

Do the same for the other speaker.


speakermaster
738 posts
 
On an old cary amp the base of the post is colored red or black it is not marked in the usual fashion look closely you will see it.
oldhvymec
5,101 posts
 
ALL of his stuff is the same way that I have. Smart actually. Yea warm those up and give them a good listen... 15 years is a long time, ay..
Keep a close eye for a FEW days ay.. Sniff and look for oil leaks, not kidding, Carys are like old Harleys, they will leak oil, LOL twice for me.
They use that same 560uf  X ??? VAC for the filter caps..

I got mad at the dog at first.. Got a quick pat on the head.. oil, no dog piss, heart attack time.. 

Enjoy..
jamesddurkin OP
4 posts
 
Thank you all for the input.  Negative toward outside edge of chassis, positive toward middle.  Just leaving this hear for the next 15 years!

twoleftears's avatar
twoleftears
5,318 posts
 
Didn't Dennis H. use a subtly colored piece of perspex under (behind) the output connectors?  Try looking at the back of the unit from slightly different angles and see if you can see a hint of red.
millercarbon's avatar
millercarbon
12,531 posts
 
Does it matter as long as I have each amp wired to its corresponding speaker the same way?
No.
imhififan's avatar
imhififan
2,183 posts
 
In storage for over 15 years, power it up in series with a 100watts incandescent light bulb just in case...

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQNxTsL4-umotgX_8DKUzPmho7DSPJzqsQ_fg&usqp=...
erik_squires
16,058 posts
 
Use a 9V battery.  When + is to +, the woofer will move towards the listener.
ditusa's avatar
ditusa
1,883 posts
 
Standing, in back of the amp the right speaker terminal is +red.            https://www.usaudiomart.com/details/649055254-cary_audio_cad300se_signature_monoblock_amplifiers/ima...
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