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Joshua Tree Attenuator, suitable input impedance for the 3-channel B22? - Page 5

post #61 of 71
8/18/10 at 9:08am
Thread Starter 

This is gonna make me confused...

http://www.twistedpearaudio.com/forum/default.aspx?g=posts&t=1216

 

Quote:
If you are using SE (RCAs), you need to either:

1) Connect ground to both sides of the JT, or

2) Install the jumper J! to share the ground to both sides.

As you have it, there is no ground to shunt to, so no attenuation.
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post #62 of 71
8/18/10 at 9:26am

Huh, I thought it was like that from the top of my head. Looks like I was wrong. You didn't swap the signal and the gnd at the input by any chance, did you? That might explain why you're getting no sound. 

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post #63 of 71
8/18/10 at 9:53am
Thread Starter 

Ok, here's the wiring diagram that I'm using:

 

4905053326_f6cb3664a9_b.jpg

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post #64 of 71
8/18/10 at 10:08am

Try switching the input and output on EITHER (ONLY 1!) the e22 or JT. 

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post #65 of 71
8/18/10 at 10:11am

Okay, I don't think that is right. lol Got a picture of the acutal wiring?

 

a) Whats the red lines on the top right?

b) Wiring should be (RCA) -> (in JTA out) -> (in B22 out) -> headphone...

 

Edit: ah E22... looking at the wiring diagram for J6 and J7:

pin 3 is the output from E22 to the input of JTA

pin 2 is the input that takes the output from JTA

and pin3 is ground.

 

Is this what you're trying to express in the diagram? Check if its correctly wired...


Edited by ujamerstand - 8/18/10 at 10:36am
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post #66 of 71
8/18/10 at 10:37am

Lil' Knight, look at the ε22 schematic.  If the diagram you posted represents what you think is the pin-order of the volume pot connections to the ε22 board, then it's wrong.

 

Also, you don't need those ground wires on the right (in blue).  The ε22 board's ground connection to the JT is sufficient.


Edited by amb - 8/18/10 at 10:39am
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post #67 of 71
8/18/10 at 6:14pm
Thread Starter 
Quote:
Originally Posted by amb View Post

 

Also, you don't need those ground wires on the right (in blue).  The ε22 board's ground connection to the JT is sufficient.

I'll take a look at the wiring again later today. Must be something wrong between the input and output.

 

I wired the JT basing on what I did with the RK27 but it's the ground wire that confused me.
 

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post #68 of 71
8/18/10 at 8:16pm
Thread Starter 


amb saved my life again :P can't believe I made such a noob mistake. I was too careless not rechecking the pins. The JTA now works correctly as it should. It does pop a little when the relays begin to click.

And yes, day and night difference from my RK27. Just like I'm listening to the Beta23 now :P


Currently using the Pico DAC as source and I don't it stress the JTA a lot. Going to modify the JTA to have fixed Zin for my tube source soon but I'm a happy camper now.

Quote:
Originally Posted by amb View Post

Lil' Knight, look at the ε22 schematic.  If the diagram you posted represents what you think is the pin-order of the volume pot connections to the ε22 board, then it's wrong.


Edited by Lil' Knight - 8/18/10 at 8:22pm
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post #69 of 71
8/18/10 at 8:40pm

Congratulations man, glad you have everything worked out.

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post #70 of 71
8/18/10 at 10:53pm
Thread Starter 

Thanks. The JTA is acting strange though, the volume is sometimes high, sometimes low when I rotated the pot. The wiring might be loose somewhere, I think.

 

I'll report back when I receive the resistor set to mod the JTA.

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post #71 of 71
8/25/10 at 7:45am
Thread Starter 

Hmm.. Just wondering if it's normal when the relays still click even when I don't adjust the pot? Aren't they supposed to be 'silent' when nothing is done? I'm using a 9v 15VA traffo.


Edited by Lil' Knight - 8/25/10 at 7:48am
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