Simple High Performance Tube MC Phono

the road not taken.
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Naz
Posts: 71
Joined: Wed Aug 06, 2008 4:27 am
Location: Sydney Australia

Simple High Performance Tube MC Phono

Post by Naz »

Following on from my previous post on my Tube LCR MC Phono I am constantly asked for a simpler, cheaper version. Moreover what really prompted this post is that it bugs the hell out of me to constantly hear that no tube is quiet enough for MC amplification without the help of a SUT or Fet Cascode, which is SIMPLY NOT TRUE! An inexpensive 6C45P is well up to the task and for those afraid to try them because they heard that these things will "oscillate in the box" to coin the commonly used phrase, it is a total myth!

SO, here is a simple high gain Tube Phono that will surprise! This configuration uses Enhanced (Passive RC) RIAA but it could easily be modified for standard RIAA.

My original version used more complicated and costly tube CCS and I still slightly prefer this but for the purpose I simplified it with Fet CCS loading as shown here. Gain with only two tubes per channel is around 73db. All three CCS active loads could easily be replaced with simple Plate Resistors of around 18K which will reduce gain by a few db but if using the better performing CCS, please note that the top DN2540 will need a small heatsink.

Obviously, the 6922 could be substituted with many different tubes and there are a few I like such as 6N1, 6N6P, 5687 and even 6H30 or 6SN7 if gain requirement is not high. In the 6922 variety the best I've tried is the Siemens Cca with 7308 Amperex another good performer, and no doubt many more. Up front I haven't found a better tube than the 6C45P which can be bought for nothing. However even here there is a considerable difference in the make and year. I prefer the Rusky tubes out of the Reflector plant, with both 70's and 80's performing well. But my best sounding pair happened to be 90's as best as I can tell.

Feel free to build it if for no other reason but to (try to) prove me wrong! Comments and questions welcome.

Naz
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stillbatt
Posts: 1
Joined: Fri Feb 01, 2013 11:20 am

Post by stillbatt »

Hi Dave

I was thinking 15 K : 8 with as much nickel as you could get in Surprised)

How expensive would this be ?
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