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I've just received the SE JTA kit and have a couple of questions: + Is there any way to fix the input impedance to 10K or it will 'automatically' vary? My source output impedance is ~1k. Also, is there any way to bring the input impedance up to 25K? If yes, which resistors should I change? + I'm going to feed the JTA by DC power. Just wondering if any of these would work fine? If yes, which one would be better? http://cgi.ebay.com/DC-5...&hash=item255af69738http://cgi.ebay.com/DC-1...&hash=item255af69784Edited by user Monday, July 26, 2010 8:38:38 AM(UTC)
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The input impedance will vary. There is no way to change that.
Either would work ok, but with one you would not need the regulator on the controller.
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Russ,
Thanks for the reply.
Could you do me a favor to post the new resistor values if I want to set the input impedance to 25K? I'm using a source that has ~1k output impedance so I guess 25k would be less work for my source.
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JT would not be a good choice for a source with an output impedance that high.
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 Is there any feasible solution for this?
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Could you point me to a simple buffer that would do the job?
Thanks
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Russ,
I remember you said there's a resistance calculator for the JTA but I couldn't find it. Could you show me where to try it?
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So I just finished the JTA, wiring it up to my Beta22. However, right after I turned on the music, the volume is already very loud, even when I turned the pot to minimum. Any hint for this?
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It sounds like you may have the audio wired incorrectly. Can you post a picture?
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Here you go:     The volumite doesn't seem to work, even when I rotated it, the sound is not louder but the relay still clicks. Somehow I broke the connectors so I just soldered the cable onto the pins directly. I suppose they are pin-to-pin matching.
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If the relays are clicking, then you don;t have a problem with the Volumite or Relay Controller.
The good news is that I think the answer is simple...
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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I just jumpered J1 and now there's no sound coming out! The input and output are shorted together.  Edited by user Wednesday, August 18, 2010 8:25:04 AM(UTC)
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Could you post a better picture of how you have the signals attached to the relay board and connectors?
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The connectors on both boards are in the same direction and I just soldered pin-to-pin.  
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Wrong signals :). I meant the audio signals.
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My bad :)I guess those connectors are wired correctly, right? Basically, it's from the RCA jacks to IN terminal block and the 4 output wires to the amp. When I jumpered J1, all the 4 terminal blocks are shorted. The relays still clicks but there's no sound coming out. When I set the knob at minimum, I hear a very quiet, distant sound but when the relays began to click, the sound disappeared Edited by user Wednesday, August 18, 2010 8:52:54 AM(UTC)
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JKay wrote:My bad :)I guess those connectors are wired correctly, right? Basically, it's from the RCA jacks to IN terminal block and the 4 output wires to the amp. When I jumpered J1, all the 4 terminal blocks are shorted. The relays still clicks but there's no sound coming out. When I set the knob at minimum, I hear a very quiet, distant sound but when the relays began to click, the sound disappeared From this it sounds like your ribbon cable is not correct. Also, you have no signal ground connection between the tube stage and amp?
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I just rewired everything and the JTA is working perfectly now :facepalm:
Thanks for your help, Brian!
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Just curious, is it normal that even when I stopped the music, the relays still click? I do here some distortions and up-and-down volume while the music is playing.
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