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Old 15th October 2011, 01:28 PM   #71
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Location: Dallas (but I am not a Texan!)
Quote:
Originally Posted by Calku View Post
220uf 450V cap Panasonic EET-UQ2W221DA under Mfg PN will not fit FPE Case. It's 30mm.
You are correct, it should end in "KF" not "DA", like the Mouser part number (which is correct). Sorry about that...

Pete
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Old 9th October 2012, 02:46 AM   #72
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Default finished my build

I decided i wanted to build an amp and after reading lots of threads here i settled on the jonokuchi to cut my teeth on. I liked the large PCB and the option that it could drive headphones or small speakers. Mr. Millett's design is very straightforward to build and other than me not paying close enough attention to the drilling pattern (i got the back panel swapped left/right) the build was quite simple. I added the 'hum' modification as shown on his web site but there is still a small amount of hum. Even with that the overall sound is quite good (currently driving with an hand me down classic ipod and using Sennheiser HD650's). Thanks Mr. Millett for answering the few questions I had. The only real modifications I made were to add Walnut panels on the ends and spray the Hammond chassis with Rustoleum Hammered Metal finish paint.
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Old 9th October 2012, 03:15 AM   #73
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Pete and others,
Just read thru' the thread and looked at the schematics etc.
It seems that some have had minor hum problems, so I ask, "Why no cap across R3?" (the bottom resistor [47K] of the heater DC elevation divider). A 10uF 63V electrolytic would help I would think, by holding the heater centre tap at AC ground.
Cheers,
Ian
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Old 10th October 2012, 01:21 AM   #74
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Default cap across R3

tried 10u 100V actually made it worse.
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Old 20th March 2013, 03:29 PM   #75
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Hi,

I was tempted to try my first tube amp, following a couple of gainclones and an O2 headphone amp. But I am a bit "terrified" by the possible dangerous high voltage of tube amps (I understood more than 300V in case of Jonokuchi).

Is this a simple and reasonable safe project?

Thank you

northernsky
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Old 22nd March 2013, 12:25 AM   #76
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Default safety

as long as you follow standard practices this is a very straightforward amp to build. if you use the design mr millet lays out (the case...) there is no high voltage exposed when operating. I have really enjoyed the amp.
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Old 22nd March 2013, 12:00 PM   #77
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not bad , I love that tube. But I think making a point to point kit would be more educational as I've seen that people struggle with tube construction techniques and I have used "the spud design" before (about 30 years ago) as a lab exercise. The low parts count makes it an excellent choice for beginner point to point.

Jonokuchi is a sutible name for something that has Edcor transformers and built on a pc board.
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Old 22nd March 2013, 02:55 PM   #78
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Hi,

thank you for your answers. I think I'll try. I'll need a lot of time: unlikely not to much free time for diy.

northernsky
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Old 25th March 2013, 02:03 AM   #79
n_maher is offline n_maher  United States
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I enjoy the heck out of mine. It's mostly used in a nearfield setup in my office but does occasional duty as a headphone amp as well. I did some slight tweaks to Pete's design in that I changed one of the front panel switches to switch two inputs on the back instead of a mini jack on the front. I also customized the front panel a bit and eliminated the 1/8" headphone output among other things. Since these images were taken I've replaced the stock power trafo with a shielded unit from SumR. I think it helped a little with the hum but I haven't added the resistors (yet?) and probably won't. It does what I need it to do well enough.

Click the image to open in full size.

Click the image to open in full size.
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Old 7th July 2013, 11:12 PM   #80
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Default First Tube Amplifier Build

I've been reading all the feedback about the JONOKUCHI - 13EM7 desktop amp and I'm thinking about taking the plunge - Hopefully I won't experience much "Hum" or someone will find a fix for the problem by the time I have completed this project.

Has anyone replaced any of the parts from the BOM with better quality ones ?(if possible)

for instance replacements for the first two parts C5, C6
0.1uF 630V coupling cap Wima MKP4-0.1/630/5PCM15
(Metallized Polypropylene)

would Mojotone Dijon Coupling Capacitors (polypropylene film and foil), rated 0.1µF to a maximum of 630 volts be a better upgrade ?
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