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Aikido Line Stage Utilizing the 5687 tube?

A

anthony101

Member
Hi everyone,

I came across several 5687 tubes in my stash from years back. So i goggled info about them and found this nifty line stage that people are commenting positive marks. So, was wondering if anyone has had the opportunity to use them in a line stage application as below? If so what are your opinions or thought about this Aikido line stage? or have you used this tube with another schematic? Perhaps you can share your project build tips or thoughts?

What do you think?

Thank you so much.

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However, I do read that they are becoming harder to find and more $$$. I think like everything, I'll build it and find out...
 
I've never used a 5687 in a line stage, although I have used them as a voltage amp and as a driver for an output tube. I have actually used them for all sorts of applications since I was introduced to them in the 1980s in a magazine article on improving the Williamson amp.

Image 1 and 2 are examples of a 5687 preamp and a 5687 transformer driver for an output tube. Notice the designers took advantage of the 5687's Gm to drive the transformers. The 5687 makes a great driver for a transformer coupled single ended triode. To use the 5687 as a transformer coupled driver, the transformer would be 10k : 10k.

The second image is a comparison of triode tubes. Notice that the 5687 has considerably more transconductance (Gm) than the 6FQ7 (6J5, 6SN7) and that makes it excellent as a driver tube, particularly direct coupled or transformer coupled. I have tried both the 7044 and 7119 as substitutes and still like the early TungSol 5687 in the end.

5687pre.gif
5687-46-Amp_-_Mar_-_05.jpg
5687 tube family specs.JPG
 
Palustris said:
I've never used a 5687 in a line stage, although I have used them as a voltage amp and as a driver for an output tube. I have actually used them for all sorts of applications since I was introduced to them in the 1980s in a magazine article on improving the Williamson amp.

Image 1 and 2 are examples of a 5687 preamp and a 5687 transformer driver for an output tube. Notice the designers took advantage of the 5687's Gm to drive the transformers. The 5687 makes a great driver for a transformer coupled single ended triode. To use the 5687 as a transformer coupled driver, the transformer would be 10k : 10k.

The second image is a comparison of triode tubes. Notice that the 5687 has considerably more transconductance (Gm) than the 6FQ7 (6J5, 6SN7) and that makes it excellent as a driver tube, particularly direct coupled or transformer coupled. I have tried both the 7044 and 7119 as substitutes and still like the early TungSol 5687 in the end.
Click to expand...
Audio Note uses 5687 in their preamplifiers using an output transformer after the tube, I think.
I designed that pcb six months ago and it sounds really good. I must say that I have a lot of NOS 5687 and 6AU6 in stock. The circuit comes from the Aikido official site.
Have a look.
6AU6.JPG
PA200006.JPGPA200007.JPGPA200008.JPGP5300015.JPG
What do you think ? No distortion or any other kind of noise.
 
FWIW. A friend of mine built a 5687 Aikido heaphone amp/preamp. He likes it a lot but I find it a little "fierce" and tight-sounding, not relaxed like my own 6SN7 Aikido. A couple of years ago I breadboarded Kiebert's "improved" Williamson mentioned by Palustris, and again found it a bit fierce, with an uncomfortable amount of gain despite the extra feedback.


(See p. 166)

The Audio Note Kit One uses the 5687 in SRPP configuration to drive the 300B, but if the schematic I'm looking at is correct, they run it at about 190 plate volts and 10-12mA current, which doesn't look very nice on the curves but sounds a lot better. IIRC, this is typical of how Japanese designers employ this tube. It sounds much nicer but still exhibits more "punch" than a 12AU7. I played with this tube and its variants (7119, 7044, 6900) years ago and found this to be the case, to my ears. I acquired a bunch of them back then and still have them, but everytime I go back to it I just find I like the 6SN7 so much better. Just my .02.
 
anthony101 said:
Hi everyone,

I came across several 5687 tubes in my stash from years back. So i goggled info about them and found this nifty line stage that people are commenting positive marks. So, was wondering if anyone has had the opportunity to use them in a line stage application as below? If so what are your opinions or thought about this Aikido line stage? or have you used this tube with another schematic? Perhaps you can share your project build tips or thoughts?

What do you think?

Thank you so much.

attachment.php


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Click to expand...
Hello, where did you find that schematic. R12 is not indicated in the part list. It is on the dc power rail. If you have any info I would be grateful.
 
Getting the info from post #1, I designed a PCB with two 5687 tubes per channel. The only thing that is missing is the value of R12. If someone has any important info about that, it will be great. What do you think about that project? Every opinion is valuable!
There it is:
5687.JPG
 
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