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PostPosted: 14 Sep 2016, 20:27 
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Joined: 01 Sep 2016, 17:19
Posts: 7
Location: Hertford, NC 27944
Hey guys..

Was curious if anyone here has used or has an opinion of this kit...

http://www.ebay.com/itm/Douk-Audio-KONDO-AUDIONOTE-KSL-M77-Line-and-Phono-AMP-Tube-Preamplifier-DIY-KIT-/281839237569?hash=item419eed79c1:g:dvIAAOSwT5tWLc5D

I've searched all over the web and all I can find is the actual amp that this is cloning, which is WAY beyond my budget.. Just wondered what the experts here think of this, and if it's worth looking into..

thanks in advance..

Mack


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PostPosted: 15 Sep 2016, 12:10 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, It is hard to tell how good it is. The photos and schematic seem OK. I would figure that it will cost over $200 more to finish the build as there are no tubes, large capacitors, power trannie, jacks, and case. Second no performance specs are given. It might be good, then maybe not.

Good listening
Bruce

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PostPosted: 15 Sep 2016, 14:27 
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Joined: 07 Dec 2015, 14:21
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I personally wouldn't use a 12AY7 for a line stage amplifier because it has way too much gain and it also makes a poor cathode follower. Much better tube choices. Since the linestage put me off I didn't bother to even check to see how accurate the RIAA equalisation is.

If you have heard one of these preamps and like it then go for it but really the design isn't anything that impressive.

On a side note I like to have my phono amp separate form everything else, I use the RCA circuit with a twist. I find I don't need a line stage amp because all my power amps are driven to full power by my digital sources the turntable is the only thing that has and needs a "preamp". I have a nice stash of 12AX7 variants that I like to roll in my phono amp :)


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PostPosted: 16 Sep 2016, 00:45 
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Joined: 01 Sep 2016, 17:19
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Location: Hertford, NC 27944
Thanks for the input guys! Just the type of feedback I was hoping for!


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PostPosted: 16 Sep 2016, 00:53 
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Joined: 08 Aug 2009, 03:11
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Location: Chilliwack, BC
Hrm, looks like a possible Jadis clone. Without reverse engineering it, hard to tell.

Cheers!

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PostPosted: 16 Sep 2016, 08:09 
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Joined: 05 Aug 2016, 14:35
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jdmcquerry wrote:
Thanks for the input guys! Just the type of feedback I was hoping for!


A few more things:

Gold is not a good contact material for things to be soldered.
Fully agreed on the 12AY7.
Things from China make me wary.
It is cheap enough, but as a circuit board, not easily modified if necessary.

On the positive side, you may experiment with many tube configurations.


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PostPosted: 16 Sep 2016, 10:37 
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Joined: 07 Dec 2015, 14:21
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Peter W. wrote:
On the positive side, you may experiment with many tube configurations.



You could just ditch the last 12AY7 Linestage section before the output and pop in a 12BH7A with different component values, should be a piece of cake. If you want to do this I can help with adjusting the power supply for the added current the 12BH7A runs at.

boo to gold contacts and boo to China, I have seen plenty of tube amps come from China with many errors, you would think they are good at maths but it's not the case, I think it's 12yo kids putting this stuff together sometimes.


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PostPosted: 16 Sep 2016, 16:14 
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Joined: 01 Sep 2016, 17:19
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Location: Hertford, NC 27944
I think I'll stay away from this one for now.. I don't wanna dump 300+ bucks into something that no one has messed around with already.. if someone here was familiar with the layout and gave the thumbs up, I was considering it.. in the interim, I already have a tubelab SSE board stashed away while I gather parts for that..

I'm going to try to find the RCA circuit and build a phone pre.. hopefully its quiet.. and hopefully you've shown some of your "twists" here, famousmockingbird!

Mack


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PostPosted: 17 Sep 2016, 21:00 
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Joined: 07 Dec 2015, 14:21
Posts: 135
Hello Mack, the schematic is pretty straight forward.

For the power supply I recommend getting something like this: http://pmillett.com/HV_reg.html

DC for the heaters.

A lot of folks use a Mosfet source follower for the output but I like to stick with tubes and so I use a plain Jane cathode follower.

Altogether you should have a pretty killer tube phono preamp for not much monies :)


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PostPosted: 18 Sep 2016, 17:56 
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Location: Arizona, USA
Hi, One thing I would change for sure if you are going to build this preamp is to not use a ceramic output cap. Back then it was probably a cost effective thing to do as large polys were costly. Not any longer. BTW it does work OK but not up to current standards. S/N is not great and it is sensitive to loading. I would not want to use anything below about 50K on it. I would probably use a ECC803S instead of the 7025. Just a personal preference. Still a fair device for a 50 year old design.

Good listening
Bruce

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