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Old 6th September 2012, 07:40 PM   #71
Jadran is offline Jadran  Croatia
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Cool The final mod of Yaqo

Here were no more feedbacks since my last post, well let me continue with my finished mod of this preamp.
After the long run I finally came to the end of this project. Iím so pleased with all what I've done here and acomplished with this modification that it will take some time before I even get used to the marvelous sound that is coming out of this unit now.
The changes include replacement of all main caps, exluding those of power, phono resistors, etc., hereís the list of all parts;

6x 1uF 5% 400V PETP K73-16 Capacitors
2x 0.1uF K75-10 hybrid
8x 0.01uF PIO Caps K40Y-9
4X Takman REX25 carbon film resistor 1/4W 2%
Alps 50KAX2 LOG type Volume Pot
3X ELNA SILMIC II Caps 25V 220uF
1X ELNA SILMIC II Capacitor 50V 2.2uF
1X Panasonic FC Electrolytic Capacitors 2700uF/25V
6X 0.01uF 200V PIO Capacitors K40Y-9
22 ohm 10W High Power Resistor
Heavy Duty 30A ON OFF Toggle SWITCH
CMC RCA Sockets Silver Plated 805-2.5AG
wooden front plate and metal spikes
+ some new wiring inside to connect new RCAs

and some pictures:
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

I have removed all Koreans Pilkor blue caps and put all NOS Russians (Soviet era) instead.
Phono RCAs are on the left side of the housing now, that way it makes front mask free. For a fun and new outlook placed this little metal dragon emblem on it. 2012 is the dragon year in China I thought it would be nice to mark my work that way. Although itís more international unit now that has mixture of parts from China, Russia, USA and UK that makes it totally different device from what it was before.
Different look that is also much more practical, so no more obstacles of the aluminum handle. But whatís most important Ė the sound! There is so much more transparency, beefier sound, details,... No more boomy bass and totally get rid of the muddy treble or harsh highs that was issue before. Sound is now very clear and crisp as it should be. With all these new capacitors this preamp simply shines. There is no annoying noise on high levels anymore, in fact Ė no noise at all, even with the volume pot turned to the end (on empty of course). AMAZING!
What I thought before that tubes makes the only difference and spent a lot of money buying and trying various lamps was totally wrong. Some, especially RCA clear tops do ring louder but none does make noise out on speakers - they are all death quiet. So now no matter what production i put in they all sound better, much much better then before, however of all I have these are my favorites; Sylvania CHS-5751 W1 and Philips JAN 6189W.

I think itís time to enjoy some old music with a new sound now!

cheers
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Old 7th September 2012, 11:13 AM   #72
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Hi Jadran, glad you're happy with yours. I have followed a slightly route, and mine also sounds better now. I will probably add Silmic or Blackgate caps at some point, and change the LED to purple, but I have other things to mod first.
List of my changes-
Replaced all the resistors in the RIAA loop with Takman metal film.
Replaced all the caps in the RIAA loop with Russian teflons.
Replaced 1uF caps with Wima MKP-10s , but the last 2 with Valab 2uF polyprops.
Replaced the 47k input cap with 1M Takman, and added a socket so I can bypass with smaller values to get the loading I want.
Replaced the 15R heater resistor with 20R - my amp is the 240v version.
Replaced the front RCAs with top mounted WBTs, in the holes where the switches were.
Replaced the valves with Mullard M8137s and RCA 5814As, for the moment.
Removed the switches, relay, volume control, output board.
Fitted connectors to transformer leads so I can easily remove board.
Used a now spare pair of rear sockets for output from the RIAA section - like the MS-22B.
Used original pair of rear sockets for output from 12AU7s.
Moved earth socket to the back.
Applied damping to transformer cover and chassis.
Made a cover, held on with neodymium magnets.
Put silly silicone rings round cans and caps!
Put silicone rubber feet on base.
Replaced the bridge rectifier and cap I blew when I rewired the transformer the wrong way!
Replaced the mains lead.
Click the image to open in full size.
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Old 6th October 2012, 09:31 PM   #73
dady is online now dady  Balearic Islands
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Hi to everybody, I have a Yaqin like the yours, but when I bought many years ago I disassembled, I got the electrolytic cap, the diodes and the transformer and putt them into the can of the transformer. The switch and the AC connector also. I keep out the pot connecting directly the valves only for use with magnetic cartridge.
Now i just find the topic and next i will show the changes.
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Old 10th November 2012, 05:25 AM   #74
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Quote:
Originally Posted by awkwardbydesign View Post
Hi Jadran, glad you're happy with yours. I have followed a slightly route, and mine also sounds better now. I will probably add Silmic or Blackgate caps at some point, and change the LED to purple, but I have other things to mod first.
List of my changes-
Replaced all the resistors in the RIAA loop with Takman metal film.
Replaced all the caps in the RIAA loop with Russian teflons.
Replaced 1uF caps with Wima MKP-10s , but the last 2 with Valab 2uF polyprops.
Replaced the 47k input cap with 1M Takman, and added a socket so I can bypass with smaller values to get the loading I want.
Replaced the 15R heater resistor with 20R - my amp is the 240v version.
Replaced the front RCAs with top mounted WBTs, in the holes where the switches were.
Replaced the valves with Mullard M8137s and RCA 5814As, for the moment.
Removed the switches, relay, volume control, output board.
Fitted connectors to transformer leads so I can easily remove board.
Used a now spare pair of rear sockets for output from the RIAA section - like the MS-22B.
Used original pair of rear sockets for output from 12AU7s.
Moved earth socket to the back.
Applied damping to transformer cover and chassis.
Made a cover, held on with neodymium magnets.
Put silly silicone rings round cans and caps!
Put silicone rubber feet on base.
Replaced the bridge rectifier and cap I blew when I rewired the transformer the wrong way!
Replaced the mains lead.
Click the image to open in full size.
You used the metal shields to cover the tubes? F*** That! I lost some Mullards and Telefunken tubes in both slots because it overheated.
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Old 10th November 2012, 12:01 PM   #75
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Quote:
Originally Posted by migkiller1971 View Post
You used the metal shields to cover the tubes? F*** That! I lost some Mullards and Telefunken tubes in both slots because it overheated.
I've had no problems with mine, even when I left it turned on for 2 days with the dust cover over it! The cans can provide some screening and damping, depending on need; as I have had no problems, I think I'll leave them on.
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Old 10th November 2012, 05:10 PM   #76
Jadran is offline Jadran  Croatia
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Quote:
Originally Posted by awkwardbydesign View Post
I've had no problems with mine, even when I left it turned on for 2 days with the dust cover over it! The cans can provide some screening and damping, depending on need; as I have had no problems, I think I'll leave them on.
You're cover is interesting, huge though, and I don't really believe it could keep the heat from tubes.
I friend of mine made the cage for my Yaq. (without even asking me, it was a surprise) but I don't use it mostly because it covers all - the switchers and volume pot. It's good as the cover when pre is not in use, though.

Click the image to open in full size.

Last edited by Jadran; 10th November 2012 at 05:17 PM.
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Old 11th November 2012, 10:05 AM   #77
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Location: Plymouth, England
Ah, but that isn't the dust cover! I use a fabric cover as my room seems to collect dust, and that WOULD keep the heat in.
Your cage looks like it should stop ANYTHING escaping! Mine was made from a spare piece of the sheet I use as speaker grills, it was just the right width. And there are no controls left on mine, anyway.
Click the image to open in full size.

Last edited by awkwardbydesign; 11th November 2012 at 10:19 AM.
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Old 11th November 2012, 01:11 PM   #78
Jadran is offline Jadran  Croatia
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Dust, always a problem yeah. These protectors are cool.
But how did you replace controls on an output board, how does it look?
Interesting idea anyway!
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Old 11th November 2012, 07:26 PM   #79
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What output board? It's gone, I connected the 1uF cap after the 12AU7 straight to one output RCA socket, and the 1uF cap after the 12AX7 to the other output RCA. That is how the MS-22B is made anyway.
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Old 12th November 2012, 11:26 AM   #80
Jadran is offline Jadran  Croatia
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Quote:
Originally Posted by awkwardbydesign View Post
What output board? It's gone, I connected the 1uF cap after the 12AU7 straight to one output RCA socket, and the 1uF cap after the 12AX7 to the other output RCA. That is how the MS-22B is made anyway.
I swear I don't drink
I didn't read well all your mods, and somehow thought that there are switches outside, silly me. Pictures help in that case, don't you have some of interior?
Also, what did you do with the front RCA if phono's are on top, they are just out of order or..?
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