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Old 13th February 2013, 09:43 AM   #1
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Default Replacing 100KAX2 with 100KBX2

Hi all,

I have a Kenwood Amplifier KA-32. The volume potentiometer in the amplifier is not working as expected even after lot of cleaning. So, I have decided to replace it with a new one.

The old potentiometer is : 100KBX2 - linear, stereo
The new potentiometer that I have is : 100KAX2 - logarithmic, stereo.

Is it okay to replace the linear pot with a log pot?

Please advice.
Thanks !
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Old 13th February 2013, 11:29 AM   #2
DF96 is offline DF96  England
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It won't actually break anything but you will get a strange law of variation when you turn the knob.
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Old 13th February 2013, 11:37 AM   #3
JMFahey is online now JMFahey  Argentina
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Agree.
On "1" it will be like the old one on "5"
"Too loud" in the first 3 or 4 scale points, "do nothing" (or very little) from 5 to 10.
It's worth searching a little more and get the Log/Audio one.
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Old 13th February 2013, 12:25 PM   #4
ingo50 is offline ingo50  Germany
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hi svkr2k
You have already the LOG -version, which will fit. But, as I remember, the old pot has a kontact
at about 50% to do a loudnes. Kenwood did this to make a lin-pot to log-pot and for loudnes.
The log-pot You already got has mybe a poor bal. at low volume and - with the loudnes-kontakt
the input-impedance of the vol-pot is about 50k ohm. Go on solder.....
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Old 13th February 2013, 04:06 PM   #5
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Default Replacing 100KBX2 with 100KAX2 (updated title)

Hi all,
i noticed an error in the title of this thread.

Carification: The pot originally in the amplifier is 100KBX2, which is linear (i hope).

The new pot that I've purchased is 100KAX2, which is log I think.

hope this clarifies.


So ... if i have the log pot instead of linear pot, what would happen?
Hi ingo50, could you please clarify your comment about the pot... sorry, I'm not an expert ...

Thanks,
Raj.
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Old 13th February 2013, 04:29 PM   #6
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Quote:
Originally Posted by svkr2k View Post
......Carification: The pot originally in the amplifier is 100KBX2, which is linear (i hope)......
No, read the replies - volume controls should be Log.
Linear pots are for tone controls, if fitted.

There can be a few types of logarithmic taper pots and this may be be just choosing between two of them. - as with a loudness tap.
However, if you can't see "log" or "audio taper" specified in the catalogue, don't buy it.
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Last edited by Ian Finch; 13th February 2013 at 04:32 PM.
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Old 13th February 2013, 04:34 PM   #7
DF96 is offline DF96  England
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Am I correct in thinking that A and B for log and lin (or vice versa) swapped over at some point in the past? I'm sure I saw that somewhere.
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Old 13th February 2013, 06:25 PM   #8
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Your 100KBX2 pot is tapped as suggested by ingo50. Check the number of terminals. If there are 4, you will be getting the wrong pot, since Ebay stuff is mostly simple "A" format - just 3 terminals. It would solve a lot of problems if you downloaded the schematic and checked this first.
KENWOOD KA-32 Service Manual free download, schematics, eeprom, repair info for electronics
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Old 13th February 2013, 07:23 PM   #9
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Quote:
Originally Posted by DF96 View Post
Am I correct in thinking that A and B for log and lin (or vice versa) swapped over at some point in the past?
I think the Japanese took the "law" into their own hands as far back as the 1960s when it was cussed about a lot in repair shops. Today, every Asian manufacturer has their own version of Japanese convention with only general adherance to those practices. Industrial part manufacturers still seem to keep faith, but then they don't really play in our league with suitable audio replacement parts.

Just for the fun of it, both A & B suffix codes are log. law here but the letters seem only to refer to the connection variations.
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Old 13th February 2013, 09:17 PM   #10
wahab is offline wahab  Algeria
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Depending on the output impedance of the circuit that precede the pot
you can add 10K to 20K resistors from center taps to ground to somewhat
"logarithmize" the whole thing.
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