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Old 2nd March 2006, 06:52 PM   #2151
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Wow UnixMan, now that would be something to see.... Not exactly my cup of tea (tubes hold no real appeal for me personally) , but it would be unique and delightfully esoteric . Maybe someone will try that. I would love to see the result.

Cheers!
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Old 2nd March 2006, 07:32 PM   #2152
Nordic is offline Nordic  South Africa
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As I said Russ, it changes the Rev C into a beast... And I used the simplest Valve buffer ECC88 circuit I could find.

It is kind of freaky how much resolution it adds to sounds, with vocals haveing much less fricative and explosive sounds, its kind of like upping the resolution on a monitor the edges becomes smoother... I think the word people sling around casualy is RELAXED.

I gotta call Willward again to go listen to his Valve hybrid system for comparison, but I think the REV C is now much closer to his leage than before... and EXTREMELY impressive for the pricepoint combined with the buffer.
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Old 2nd March 2006, 10:09 PM   #2153
phofman is online now phofman  Czech Republic
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Nordic, could you please describe your solution with ECC88 a little bit in detail? I have built MyRevC, I like the sound a lot, but the tube sound attracts me too. I even have some E88CC, and perhaps the +/-35V supply could suffice for these tubes. I am really excited about this.
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Old 2nd March 2006, 10:20 PM   #2154
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Default Buffer

Nordic,
You might want to try the ad815 as a buffer. I have a couple tube buffers, 6DJ8, 12BH7, and 6080. The AD815 bests all three.
It transformed the sound in my system. More extended, tight bass. It also revealed unheard flaws in the sources. Used to think my disc player sounded fine after 10 minutes. Now there is a little sharpness, and it rounds out after about an hour.


George
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Old 2nd March 2006, 11:06 PM   #2155
Nordic is offline Nordic  South Africa
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Yep, I'm kinda waiting on Rudi to say he is done with his preamp circuit, then I'll build it

Phofman, I'll post some details tommorrow, its past 1 in the morning here now, need some sleep.
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Old 2nd March 2006, 11:38 PM   #2156
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Quote:
Originally posted by phofman
Nordic, could you please describe your solution with ECC88 a little bit in detail? I have built MyRevC, I like the sound a lot, but the tube sound attracts me too. I even have some E88CC, and perhaps the +/-35V supply could suffice for these tubes. I am really excited about this.

Nordic is actually talkin about a completely different amp. This one here:

http://www.diyaudio.com/forums/showt...618#post762618
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Old 3rd March 2006, 01:03 AM   #2157
troystg is online now troystg  United States
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"REV C with Fran'z valve buffer"

Franz's amp is a tube buffered LM3875. I have that one also. I "believe" Nordic took the tube board section and just made a buffer for his Rev_C. It would be VERY difficult to integrate the tube into the circuit instead of the LM318 UNLESS you are very skillful. I belive it was just mentioned in a recent post, but it's not something I would attempt without a thorough inventory of test equipment.

Edit: It was UnixMan who explained how to swap opamp for tube. It was a good write up .


But I personally will stick to what the designer had intended as thanks to Mauro for his time and gift. It has really brought me many hours of joy... Thanks to Brian and Russ for the kits too.
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Old 3rd March 2006, 01:37 PM   #2158
Nordic is offline Nordic  South Africa
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Sorry I haven't posted yet, still feeling dead after 3 nights of late music listening... Like someone said before, I used a small alps pot, the Buffer from Franz's amp and the full Rev C
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Old 10th March 2006, 03:18 PM   #2159
Asen is offline Asen  Bulgaria
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Sorry for mentioning that question one more time but I have read the Mauro's paper, and Russ's post #2134 and it is still not clear to me what makes the input impedance 100k, and not 3k3, as far as the (-) input of the OPAmp is a low-Ohm one.
Can somebody please explain that to me? Thanks!
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Old 10th March 2006, 03:43 PM   #2160
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Quote:
Originally posted by Asen
Sorry for mentioning that question one more time but I have read the Mauro's paper, and Russ's post #2134 and it is still not clear to me what makes the input impedance 100k, and not 3k3, as far as the (-) input of the OPAmp is a low-Ohm one.
Can somebody please explain that to me? Thanks!

Read this post and the next several to answer your question:

http://www.diyaudio.com/forums/showt...230#post697230

especially this post:

http://www.diyaudio.com/forums/showt...036#post698036
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