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Old 9th January 2013, 09:43 AM   #51
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Thanks for sharing the pics, your headphone amp seems shine like a gem.
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Old 24th February 2013, 06:20 PM   #52
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Can I use 100R for R4, I'm using ECC88 in place of 6DJ8? I only have 120R of 1/4W can be enough?
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Old 25th February 2013, 10:48 AM   #53
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C3 can be 2000uF in place of 2200uF?
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Old 25th February 2013, 11:31 AM   #54
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Could I use LEDs in place of cathode RC?
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Old 25th February 2013, 03:11 PM   #55
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Quote:
Can I use 100R for R4, I'm using ECC88 in place of 6DJ8? I only have 120R of 1/4W can be enough?
Should be okay, but better parallel two 220R 1/4W...
Quote:
C3 can be 2000uF in place of 2200uF?
Yes, it can be as small as 470uF. 2200uF is calculated for a low frequency of under 1Hz or so (from the top of my head), so 470uF is good. Tip: use 2x220uF Oscon... a worthwhile improvement.
Quote:
Could I use LEDs in place of cathode RC?
Yes, in the first stage. Don't know about using LED's in Cathode Followers...
Didn't I send you my schematic of the Morgan Jones with LED bias...?
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Old 25th February 2013, 03:15 PM   #56
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Quote:
Originally Posted by Stixx View Post
Should be okay, but better parallel two 220R 1/4W...

OK

Yes, it can be as small as 470uF. 2200uF is calculated for a low frequency of under 1Hz or so (from the top of my head), so 470uF is good. Tip: use 2x220uF Oscon... a worthwhile improvement.

Perfect I have BG 220uF 16V

Yes, in the first stage. Don't know about using LED's in Cathode Followers...
Didn't I send you my schematic of the Morgan Jones with LED bias...?
Yes I see that you are using LEDs in the input tube but I have the same doubt like you to use it in the white cathode follower?

What about R7, somw people said 10K in place of 22K?

Last edited by merlin el mago; 25th February 2013 at 03:29 PM.
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Old 25th February 2013, 05:39 PM   #57
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What about R7, some people said 10K in place of 22K?
I guess this one only serves when no headphones are connected... in my build I was using 47K. Sonically not relevant for sure.
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Old 25th February 2013, 05:42 PM   #58
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Thanks
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Old 25th February 2013, 06:31 PM   #59
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Click the image to open in full size.

Here, download a copy of LTspice and have a play with these. Put the file 'dmtriode.inc' in the same directory (C:\Program Files\LTC\LTspiceIV) you put the 'MJ_6DJ8_optimized.asc' file in. Open the .asc file, right click on the schematic and select run. The simulation will run. Click on Vout to see the sinewave. Rightclick on the sinewave and select 'View\FFT' to see the FFT. You can substitute values or put in an LED and see the effect. Go 'View/Spice Error Log' (after running the Transient simulation) to see the THD. If you right click and select 'Edit Simulation Cmd.' you can simulate the AC (frequency) response or find the DC operating point.

Morgan_Jones_headamp_optimized.zip
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Old 25th February 2013, 06:44 PM   #60
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Amazing, thank you.
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