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Old 20th February 2011, 02:26 PM   #21
bazouka is offline bazouka  France
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Quote:
Originally Posted by MrCurwen View Post
The 6N1 is not a replacement for 6DJ8/ECC88/6992. It has different plate resistance, and so different curves.

A suitable replacement would be the 6N23. There is no western equivalent to the 6N1.
on this amp, there are 3 choises for tubes on the PCB : 6N1 (came with the amplifier) and 12AU7 and 12AT7
here are photos showing the prints on PCB :
Outer tubes :
Click the image to open in full size.
Inner Tubes :
Click the image to open in full size.

I am not sure the circuit is perfectly tuned for 1 type of tubes, I should measure voltages on mine to see, also there are multiples versions on sale, they differ by some components.
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Old 3rd March 2011, 03:05 AM   #22
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Since the tubes are for the preamp only, havent noticed any difference when rolling them from the stock Shauguan's. I did get rid of the wire holders that must of had 50 foot pound or torque "smashing" them in place. That couldnt be good.

I finally replaced a few of the caps with Nichicon muse. Not a lot of improved difference, and probably shouldnt have done so as the muse are not high temp as the crappy stock caps were...

I wanted to say again that any VK-2100 owner needs to do heat management and venting at a minimum, and check the output bias per another thread from a couple years ago on the same subject. Dont know of a single VK-2100 out there from the factory where the outputs are correct and have been at least close to correct and matched.

Ive got about 500 hours on mine now, and I'm telling you this amp is still a best bang for your buck. I found the knobs to be too slick for daily use and touching, and added some large diameter industrial heat shrink to mine (black). It looks good and now provides some grip and protection.

Still waiting for a woodworker (worldwide) to make a new cover for one out of exotic or mixed high grade wood, with added venting. Not being a woodworker, always wanted to see that and obtain one myself somehow. It would look soo much better!

Steve M- when youre rockin, have you gone past 50% on the volume yet? Mine cranks out huge db's at even 50%!
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Old 3rd March 2011, 08:49 AM   #23
bazouka is offline bazouka  France
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Hi,
Stock Shuguang is really Too smooth and shy, week on highs, and more important, bass is boomy, on complex music everything becomes relatively messy very rapidly.

With the 6N1P-EV, everything is much clearer in the highs but the biggest improvements was the bass, more slam, much less boomy, but everything keeps a lot of sweet, no aggressiveness, it is impossible you didn't notice the difference it is really an upgrade !!!


For the Bias just look to the DOC
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Old 3rd March 2011, 08:39 PM   #24
Salas is offline Salas  Greece
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Quote:
Originally Posted by bazouka View Post
I inserted the photos above as thumbnails from imageshake, this didn't work as expected and the photos are too small, also I am unable to edit the post, so I put them back here, I hope they will work correctly this time, sorry for the inconvenience :
You can resize and upload as attachments each time, as I just corrected.
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Old 5th March 2011, 03:10 AM   #25
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Hey! They finally changed the thread name! Now, if we could only get a forum specifically for Yaqin, or Chinese invasion amps alone. Would really help since so many own and mod/improve them now.
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Old 5th March 2011, 07:03 AM   #26
bazouka is offline bazouka  France
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Great !!
By the way I finally understood the electronic diagram!!
Why did they draw each triode as a separated valve ??
Is this conventional ?
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Old 5th March 2011, 08:12 AM   #27
bazouka is offline bazouka  France
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I did some mods lately :

I replaced all the noname blue capacitors of 0.47uf by some ERO 1840 0.33uf 400v, and added one of those to each of the capacitors between the tubes.

I decoupled the 10000uf caps, by a 10uf MKP each + russian k42y2 0.33uf (because i have them !).

I removed a Connecter under the PCB and soldered the wires directly to the board.

Finally I replaced the IEC socket with a Schaffner 9226-3-02 filter, it needed some work on the case but I was really minimal.

It gained a lot in the bass department, more controle, the highs are "more stable" while hearing some strong voices at loud levels it is less aggressive, smoother, and bizarrely the amp seems to have gained some power, It can sound louder without distortion than before the mods, Great .

here are pics of the old socket (I had some 0.1uf x2 ceramic capacitors for filtering, not bad for cheap amp !!) :

Click the image to open in full size.

and the new one too
Click the image to open in full size.

By the way if an expert can have a look at the diagram in the page 2, and can give us some tweaks or mods, this would be great, do not hesitate !!!

Last edited by bazouka; 5th March 2011 at 08:20 AM.
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Old 8th March 2011, 03:07 AM   #28
Steve M is offline Steve M  Australia
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I lent my Vk2100 to an audio buddy of mine and he didn't quite like the sound of it. He found it a bit bright and forward. I think he does quite like a warm and neutral tone, so not too surprised by his comment.

Playing the VK2100 through my Yamaha NS-1000x speakers (which are very revealing), I just find the amp very detailed and fast sounding, no smearing of bass notes into the important mid-treble region, giving a clear and open presentation - that's why I like it.

Rockmore: I find the amp plays plenty loud at 12 o'clock on the volume dial, no need for any more. I haven't tried it into a difficult spkr load yet though, I'll have to try it with my Spendor BC-3 spkrs which usually require a bit of driving!

Also, does anyone know the stand-by or general power consumption of this amp ??

Regards,

Steve.

Last edited by Steve M; 8th March 2011 at 03:09 AM.
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Old 9th March 2011, 06:56 AM   #29
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Your Yahama and Spendor's need the VK-2100's extra punch if you ask me. Those old school factory made designs really don't bring out the potential of this amp. But glad youre enjoying it! Ive ran mine with three different sets of speakers, all very efficient, and currently running these Tritrix TL's I made. Couldnt be happier so far.
Google Image Result for http://i635.photobucket.com/albums/uu80/dhancoc/PICT3801.jpg

Like I said before, there was a guy who posted a big thread about the output balancing somewhere back a few years ago. Cant remember if it was here or on AK. Really makes a difference. Bet "your friends" speakers are old school factory bought. I also run two full tube amps, and still love my VK-2100 with the heavy duty Japanese transistor outputs. 12 O'Clock is 50%; and that's more than enough like you said. Ive got mine running through a 12" powered sub also for parties, etc. It's just great.

Bazouka- that's a lot of work! Hope it's been worth it, and would be interested to hear about the mid/long term benefits of your mods. Keep sharing step-by-step specifics of your mods, and part numbers/vendors for what you've said you've replaced. I have not found any actual beneficial parts replacement for any of the caps vs whats stock.

I'm telling you- we've got to find a VK-2100 lover who is a woodworker. Cosmetically, this thing would look great with a custom exotic wood case with a semi-gloss coat, WITH plenty of venting.
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Old 10th March 2011, 03:08 AM   #30
Steve M is offline Steve M  Australia
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Rockmore: your speakers look very nice, is that a Dynaudio Esotar (or Morel) tweeter you are using in the d'appolito configuration?

As to the Yamaha NS1000-X's they are quite a different beast to the normal NS1000, they are much more efficient, with better imaging and lots more bass. I don't know about them being old school? The beryllium drivers in the Yammy are unsurpassed (and copied in recent times by Focal JM Lab etc.). I'm not sure the plasticky cones in your DIY effort could really keep up with the Yammy drivers for ultimate detail retrieval ?? Just an opinion though, as I have not heard your speaker ...

Besides, I have access to a large collection of efficient speakers (both my own DIY efforts and commercial spkrs) to try the VK2100 amp on, see my system pics and story here: AudiogoN Forums: Supratek Grange Based System or here http://cgim.audiogon.com/cgi-bin/vs....tem&82&showall

Regards,

Steve M.

Last edited by Steve M; 10th March 2011 at 03:10 AM.
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