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Old 6th December 2009, 05:49 AM   #1
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Default Help with Morgan Jones headphone amp

I usually post at HeadWize, but the forum is down so I am here for some help, if you'll have me! I just finished my Morgan Jones Earmax copy with feedback

HeadWize - Project: The Morgan Jones Mini Tube Headphone Amplifier by Chu Moy

What I want to do is put bypass caps on the headphone jack so that when I plug in/unplug the headphones there is no POP. Just wondering what a good value/rating would be for these caps. Thanks in advance for any help! Oh and the amp sounds fantastic, great detail and warmth, much MUCH better than listening plugged into my computer or iPod directly.
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Old 6th December 2009, 09:00 AM   #2
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1. Switch-on the PS, without headphones.
2. Inplug headphones after 30 sec. /U R7 will be aprox. 0 v/
3. Unplug Headphones.
4. Switch-off PS.
/You can put R7=10 kohm, instead 22 kohm/

Last edited by azazello; 6th December 2009 at 09:05 AM.
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Old 6th December 2009, 10:47 AM   #3
Stixx is offline Stixx  Germany
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It makes me wonder why there is a POP in the first place...
I've built the same amplifier (and a few others also), and none of them exibits any noise when plugging/unplugging headphones...
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Old 6th December 2009, 05:12 PM   #4
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azazello, I'm not sure I undestand. In what case would I want to change the value of R7? What is the benefit?

Stixx- It's not that there is an immense pop or anything, just the normal crackle of unplugging headphones, my thinking was that I could minimize this with a cap from R and L to ground.
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Old 6th December 2009, 05:29 PM   #5
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Trevorjn,
Non obligatory to change R7, but You can try....
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Old 6th December 2009, 09:35 PM   #6
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Anyone? I'm am changing out R7 as I type this (I did put my iron down for a second but what about the caps? If I do put them in will it negatively effect the sound?
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Old 6th December 2009, 10:47 PM   #7
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So with R7 at 10K when I switch on the amp with no load I see the VDC across the output go up to 50v over the coarse of about 3 seconds, then back down to zero after about 4 seconds. WTF? The output caps were totally discharged when I turned it on, could this have something to do with it?
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Old 6th December 2009, 11:52 PM   #8
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If You put small cap, You will loss the bass !
The cap must be Black Gate, ELNA, Nichicon for good quality of music.
If there isn't R7, on output there is U = Ua output tube.
When You plug the headphones You will hear big PUP, and maybe You will loss Your
headphones. Thank to R7 after 30-40 sec, Uoutput will be aprox 0 !
With 10 kohm U out will go faster to 0 .

Last edited by azazello; 7th December 2009 at 12:02 AM.
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