Replacing 100KAX2 with 100KBX2

[svkr2k]

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 !

 

[DF96]

It won't actually break anything but you will get a strange law of variation when you turn the knob.

 

[JMFahey]

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.

 

[ingo50]

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.....

 

[svkr2k]

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.

 

[Ian Finch]

......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.

 

[DF96]

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.

 

[Ian Finch]

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

 

[Ian Finch]

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.

 

[wahab]

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.

 

[svkr2k]

Hi all, Thanks for the advice. I'm glad that I'm a member of this forum !

Here is the one I have bought recently as a replacement:
1pc Potentiometer 100K Log Alps Audio Amp Volume Control Pot Stereo w Loudness | eBay

(fyi : The original pot in the amplifier also had center taps)

 

[svkr2k]

Hi all, Thanks for the advice. I'm glad that I'm a member of this forum !

Here is the one I have bought recently as a replacement:
1pc Potentiometer 100K Log Alps Audio Amp Volume Control Pot Stereo w Loudness | eBay

(fyi : The original pot in the amplifier also had center taps)

Hope it is okay to use the new pot in the amp?

 

[svkr2k]

Hi all,
Is this pot fine?
1pc Potentiometer 100K Log Alps Audio Amp Volume Control Pot Stereo w Loudness | eBay
Thank you.

 

[Silversteel]

I have a stereo amplifier which had the same problem with the volume potentiometer. It has also the same reference 100KBX2, also four connections and has even another feature that I like very much: in the back of the double potentiometer and also connected to the spindle, it has a gear which has its teeth engaged in a sphere pressed against them making the "clic-clic-clic" feeling when one turns the potentiometer. The potentiometer was not working properly as in most off the travel there was no sound; sometimes the sound came but was in positions where the volume was too loud. Therefore, was impossible to select a proper volume.


Following the suggestion in the beginning of this thread, I applied on the inside of it (from two openings that it have in its case) a little of contact cleaner (Philips contact cleaner 390CCS), turned several times the spindle to the left and then to the right and allow some time to dry. After that, I tried the amplifier and the potentiometer was now working properly!!!

 

[east electronics]

No matter what the schematic or the type of pot is stated in a volume application there has to be a log pot

Checked with the schematic of your amp and there is NO linear pot together with resistors to make it log .So the original pot was LOG one way or another

Proceed !!