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Noble AP25 pin help

post #1 of 15
11/7/05 at 5:28pm
Thread Starter 
Been looking for a while for a data sheet without success. Just need to know which pins are what. Any help would be much appreciated.

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post #2 of 15
11/7/05 at 5:37pm
ABC/EFG are the same as an Alps Blue. D and H are used for connecting to a balance control or something like that. You can clip them.

A side note about the Noble: the plastic element is very meltable. It is a good idea to sink the leads when you solder, and only use as much time/heat as absolutely necessary.
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post #3 of 15
11/7/05 at 5:43pm
Just to be double sure check this link.

HTH,

Nate
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post #4 of 15
11/7/05 at 5:43pm
Thread Starter 
Gotcha, So
A,E= Ground
B,F= Out
C,G= In
D,H= Balance

Thanks for the help!!
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post #5 of 15
11/7/05 at 6:14pm
It's a "loudness tap" actually. We don't generally play that game in headphone amps, so you can clip it.
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post #6 of 15
11/7/05 at 7:33pm
Quote:
Originally Posted by HiGHFLYiN9
Gotcha, So
A,E= Ground
B,F= Out
C,G= In
Yup
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post #7 of 15
12/26/09 at 8:24am
resurrecting this old thread..

I am having problems with my EHHA in which I am using the Noble AP25 10k pot.


One of the channels is sounding like it is being grounded. Specifically the right channel. The vocals instead of being centered is heavily focused on the left channel with the mids having an echo signature to it in the right channel albeit faint, the bass sounds sucked out as well.

So if I disconnect the right channel RCA cable, I am hearing from both channels of the amp board but it sounds like it is in mono with everything being centered.

If I disconnect the left channel, I only hear the right channel which is how it should be and it is sounding just fine.

I have tried replacing the Noble pot with another AP25 and the results are the same.

Appreciate any input.
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post #8 of 15
12/26/09 at 8:45am
Check the wires, sounds like have the signal input and ground crosswired on the left channel
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post #9 of 15
12/26/09 at 9:17am
Quote:
Originally Posted by MisterX View Post
Check the wires, sounds like have the signal input and ground crosswired on the left channel
Hey Marshall, Thanks for the reply..

Double checked this...will post a pic shortly for reference.
I tried shunt modding the NOBLE and also in regular configuration and both give me the same result.
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post #10 of 15
12/26/09 at 12:29pm
Quote:
Originally Posted by sachu View Post
Hey Marshall, Thanks for the reply..

Double checked this...will post a pic shortly for reference.
I tried shunt modding the NOBLE and also in regular configuration and both give me the same result.
Any chance you got it too hot as mentioned above? Does the pot ohm out OK?
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post #11 of 15
12/26/09 at 6:41pm
Quote:
Originally Posted by les_garten View Post
Any chance you got it too hot as mentioned above? Does the pot ohm out OK?
Hey Les,
Yes it all checks out fine..
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post #12 of 15
12/26/09 at 9:17pm


Okay..here is how I have wired my pot at the moment.

Two riken 9k resistors for shunting.

The signal chain is input -> riken->A/E-> out
B,F,C and G are all grounded together.


Shunting the pot has been done as per this post here
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post #13 of 15
12/27/09 at 4:31am
a quick confirmation..the NOBLE AP25 is the same as the NOBLE 204Y?
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post #14 of 15
12/27/09 at 1:27pm
Just FYI, I had an issue on the 204y where I did overheat, and the I -> G on one channel was open, so I had to add a dollop of solder to reconnect the G pin side. The '10k' actually measures 8.67k on one deck and 8.52k on the other.

At this juncture, not a fan.

Oh, and file photo:

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post #15 of 15
12/31/09 at 8:06pm
OK, so I am even slower on the uptake on this than usual, but so tired of futzing with it.

This is the amp completely built and biased, all except for getting my freaking pot connected correctly for the shunt.

Coming out of the ll1544a, there are 2 10k shunt resistors going into the pot as a variable resistor, not a voltage divider. But, how do I wire this stinking pot to serve this function?

Yes, I looked here, but it doesn't match my prior guidance (and, I can't see the variation on the meter, so I am losing the fox). Again.

If I understand, all I need to do is wire the two leads coming off the 10k shunt resistors to pin A on one deck, and E on the other for the two channels? Then ground pins B, C, F & G? How do I see this to understand (for even the briefest of fleeting moments) on the meter?

Now, if I read further, the shunt resistor should be LESS than the pot, but, in my case, the 10k resistor is greater than the 8.67k pot. Kevin (K&K) tells me for extra gain, it is also ok to use a 50k pot here, which is the lesser evil than changing the shunt resistors to 5k.

The struggle continues.
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