Yaqin MS 12B phono amp- reviews - Page 6 - diyAudio
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Old 14th May 2012, 07:28 PM   #51
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Hi!

I have owned the MS-12B pre a couple of years now. A friend with electronic skillz recommended it.

So, purchased it, and he helped me do the mods.

He told me to get JJ ECC82/ECC83(I think).

And he replaced the two caps that looked like this:

Click the image to open in full size.

With a matched pair of this russian NOS paper-in-oil caps:

Click the image to open in full size.

It really changed the sound from average to outstanding! It sounds very expencive, but is not.

About the pot, is it a dual 100kOhm? I got a blue alps like that and if it is a match it will go in there.
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Old 14th May 2012, 07:39 PM   #52
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Default Resistor

Still need to know if I can replace that 15 ohm 7 watt with a 22 ohm 5 watt? Thanks for the other info though.
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Old 14th May 2012, 07:53 PM   #53
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Did you use two matched
POI's for each 1 uf cap
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Old 14th May 2012, 08:30 PM   #54
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Quote:
Originally Posted by Rolli666 View Post
Did you use two matched
POI's for each 1 uf cap
No, sorry. One per channel.
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Old 15th May 2012, 01:17 PM   #55
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Location: Plymouth, England
Quote:
Originally Posted by Rolli666 View Post
Still need to know if I can replace that 15 ohm 7 watt with a 22 ohm 5 watt? Thanks for the other info though.
If no-one else will help, try this; Ohm's Law Calculations With Power
If I have it right, you want to drop 10 volts, as the heater transformer is 16v, x 1.4 rectified and smoothed, =22v. 22-10=12v. Using the calculator, I get 4.5w dissipation, which is pushing it a bit for a 5w resistor. As I use a 20R resistor to get 12v (22R gave me 11v), that dissipates 5w, so I got a 10w resistor here- eBay - The UK's Online Marketplace. He doesn't seem to have any more at the moment, but I have a spare if you need it. Why do you want to use a 5w? 10w WILL fit, only just.
Hopefully someone more expert will help, but that is the best I can offer.
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Old 15th May 2012, 01:33 PM   #56
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By the way, removing or bypassing the volume control, output board, relays improved things. I also removed the 2 push button switches and put in a pair of WBT RCA sockets instead (I already had them), so the phono inputs are on top. Replaced the RIAA resistors with Takman metal films, and the caps with Russian teflons. Changed the input loading resistors to 1megs (for my Decca) and then paralleled them to get what I want. DIL single pin sockets to make them plug and play. Outputs from RIAA section or normal output via different sockets. At the moment it sounds better going through both sections, but I have TVC preamp, so YMMV.
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Old 15th May 2012, 01:54 PM   #57
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Quote:
Originally Posted by awkwardbydesign View Post
By the way, removing or bypassing the volume control, output board, relays improved things. I also removed the 2 push button switches and put in a pair of WBT RCA sockets instead (I already had them), so the phono inputs are on top. Replaced the RIAA resistors with Takman metal films, and the caps with Russian teflons. Changed the input loading resistors to 1megs (for my Decca) and then paralleled them to get what I want. DIL single pin sockets to make them plug and play. Outputs from RIAA section or normal output via different sockets. At the moment it sounds better going through both sections, but I have TVC preamp, so YMMV.

This is a absolutely fantastic Phono/preamp if you are starting to get into tubes. I can't recommend it enough. I've added a better Volume pot, I have 1 UF sonicap gen 1 bypassed with sonicaps gen 2 .01 UF caps. I've added bradley allen gridstoppers. I have caddock's 47K resistors. I've also added some bypass caps in the powersupply. For the price, its unbeatable. This preamp has given me more joy than the $1200 Cornet 2 I have. I have to double check everything and put up the Yaqin for sale. All its doing is collecting dust.
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Old 15th May 2012, 02:01 PM   #58
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Here is the insides: And yes, those are Blackgates capacitors in there.


Click the image to open in full size.


The UnderBelly: you can see the Bypass Caps, 47k resistors, Gridstoppers
Click the image to open in full size.
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Old 15th May 2012, 02:57 PM   #59
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Quote:
Originally Posted by migkiller1971 View Post
. This preamp has given me more joy than the $1200 Cornet 2 I have. I have to double check everything and put up the Yaqin for sale. All its doing is collecting dust.
Have I read that right? Why is the Yaqin for sale if it has " has given me more joy than the $1200 Cornet 2"?
Also, is the 4 pin connector from the tranny original, or did you fit it? And my unit is a 240v model so 20R is better for the 5814 (ECC82) heaters.
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Old 15th May 2012, 03:31 PM   #60
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How much do you want for it?
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