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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Jean Hiraga SE KT88

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Nikon1975

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Joined 2009
#1
Did anyone assemble this amplifier ?

I got interested as the schematic contains a level of details that is unusual. From what i understand it should be very dynamic, maybe with not so low distortion.

do you think it is worth the effort ?

Thanks,

D.
 
#4
http://www.diyaudio.com/forums/tube...8-build-abdellah-diyaudioprojects-design.html

I would suggest reading this thread to see what people think of a similar design. You may wish to use a different feedback method, use triode mode, or pentode mode. If you really want to build this design I would suggest using a 6SL7 in the first stage. However, Hiraga is well respected and why mess with success.
Many people like the sound of SET amps after hearing them and have made them a permanent part of the system.
 
#5
I used this schematic as well as a few other kt88/el34 designs floating around, as the basis for my most recent project. I used 2 sections of a 6sl7 as the driver, and it's wired as a power amp so I can use various line stages in front of it (with volume control). I love the sound of this amp. I concentrated on its versatility so with a change of rectifier tubes and/or cathode resistors you can use so many different output tubes. Also switchable from triode to ultra-linear. I haven't attempted any nfb yet but as I said, it sounds terrific already.
 
#7
In my opinion you have much flexibility with the abdellah amp. I don't think you would get better sound with the Hiraga, just different. With the abdellah amp you can use different tubes and change to various types of operation. The 12AX7 is not my favorite tube, bu you could use a 6SL7 in an SRPP first stage like Hiraga, in your abdellah amp. Or use the 6N1P or 5751 in SRPP. You can try using higher quality components in the abdellah. The output transformer could be upgraded. I would not suggest building the Hiraga, just trying different things in your abdellah. Just my opinion.
 
#8
I totally agree with dshortt9. It is such a versatile design, you can make a few simple changes to the amp you built and get the Hiraga sound.
I like making changes to my amp one thing at a time so I know exactly how it changes the sound. Playing around with caps, resistors, even changing the value of Rk and changes to th power supply make noticable changes in sound. Maybe better OPT's, adding ultra-linear switch, get rid of electrolytic caps etc...etc....
Good luck with it! I hope you have as much fun with yours as I do with mine!
 
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