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 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

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PostPosted: 30 Sep 2009, 01:22 
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Joined: 02 Sep 2008, 23:22
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Location: Australia
Hi all,

Here is my second Jean Hiraga - Le Monstre 8W Class-A Amplifier build....
Attachment:
Jean-Hiraga-Le- Monstre-PCB2.jpg

If you want to see some pics of the performance and the amp have a look at:

http://s300.photobucket.com/albums/nn26/danw1million/

there is some ringing at higher frequency square wave but I will work out a cure for this. however i think it is just the measurement setup leads ps. etc.

-Dan


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PostPosted: 30 Sep 2009, 16:06 
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Joined: 14 Oct 2008, 17:35
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Location: Dartmouth, Nova Scotia
These pictures could actually be helpful to me for when I decide to construct this amplifier. I have a large U shaped peice of aluminum that I can attach to the chassis as a heatsink, I have a 15-15V 225VA Hammond turoid (plan on purchasing a second one so I can make dual mono setup), I have two fully regulated 12V dual rail power supplies 2Amps per rail, and two massive sprague 41000uF 50V screw terminal caps.

I see Audio Note gold!!!!! :)

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PostPosted: 30 Sep 2009, 18:13 
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Hi Dan, the square waves are showing overshoot that your original build did not show. Are you using different devices for this build?

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PostPosted: 30 Sep 2009, 19:21 
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Hi Gio Hi "CrazyabtTubes"

I have changed the lead config slightly and there is a slight change but not alot.

I think the "overshoot" is due to the new output stage i have used (possibly) which is 2SA1186/2SC2837

since the transistors are so fast (60 MHz) i think perhaps even too fast !!!

I may actually change them to say 2SC5200/2SA1942 or similar (30MHz)

the original has 15MHz output stage so perhaps this is why...

PS I am not sure if the speed on the square wave even matters for this because the sine response is quote good.....
and neither are music :)

-Dan

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PostPosted: 22 Oct 2009, 21:58 
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just so you guys know second set of wave forms are up :

http://s300.photobucket.com/albums/nn26 ... nt=012.jpg

The overshoot was actually due to a test lead, the test wiring and the test load.... and bias was a little high too (1A) rather than 0.5-0.6A not that this will hurt.

Compare the 100kHz square waves and let me know what you think.

-Dan

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PostPosted: 23 Oct 2009, 17:31 
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Wow Dan, those high frequency waves look fantastic! Have you had a chance to do some listening?

Are you planning on replacing the previous modules or will they get a new home?
Cheers

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PostPosted: 23 Oct 2009, 19:35 
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Thanks Gio,

I was pretty happy with the results on the MSO, have not had a chance to listen yet... soon though - will keep you guys posted

-Dan

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PostPosted: 24 Oct 2009, 10:56 
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That is looking good Dan, soon I will have my first class "A" amp up and running. :)

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PostPosted: 24 Oct 2009, 15:58 
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Thats great the le class A 20W i assume you mean ?

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PostPosted: 26 Oct 2009, 17:11 
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That is the other option as the future, the le class A I have more parts for as it uses BJT's rather than FET's but I also have the F5 well in mind, it all depends on what I can gather up. :)

The one I am working on now is like the DIY class A 2SK1058 amplifier, but uses an 2SK643 and will have a tube pre/driver stage using EL34 and 6AS7, that oughtta keep my room warm. :hot:

I would really like to know how the le class A would compare to the F5 since there are major differences between the two, one being a FET output and the other being BJT output, which amplifier would be more suited for the sinks I have? :hot: :cold: :hot: :tombstone:

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