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I have been having more fun listening to my system in the last week than at any time in recent memory, all due to my new Aikido line amp. Now the Aikido is not a specific piece of equipment. Quite the opposite. It is a novel circuit that can be applied to many tubes for line, phono, power amp input/driver, etc. Go to WWW.tubecad.com/2004/blog0011.htm for a broad outline of the concept.
I was attracted to the circuit because I have this sick habit of collecting interesting tubes with no equipment to use them in. What does a 6BL7 cathode follower sound like compared to a 6BX7? I don't know (but I will). How about a 6N1P compared to a 5687? Depending on how you apply the Aikido concept you can substitute a wide variety of tubes with no change in circuit values for quick comparison.
Now I knew an Aikido line amp was unlikely to match my fully tricked out Ultrapath but it would be fun to play with, simple to build and I had most of the required parts in mt closet. My prejudice is for simple circuits and wildly overbuilt power supplies. I was able to use my Ultrapath outboard raw power supply which made the build even easier. John Broskie talks about the nature of the circuit allowing a less than steller power supply without much of the penalty you might otherwise pay. I'm just not interested in going that direction. I'm using all oil caps, full wave schottkey bridge to criticly tuned choke input (plus plenty additional chokes), etc. Big and heavy.
A casual read of the referenced article gives you the impression that all you are gaining from the Aikido is a reduction in power supply noise. Don't believe it. Something semimagical is happening with this circut to get rid of all kinds of power supply weirdness.
OK, so I fire it up for a smoke test and hooray...no smoke. No loose, phasey in need of breakin oil cap sound as I expected either. (Old GE rather than new ASC?) It sounded nice from minute one. I started out with 4 GE 6SN7GTB in case something did go wrong. Maybe it sounded a LITTLE sharp or brittle? Not much. Couple hours later with NU black glass GT's in the front end and I found myself with this kind of silly grin on my face for no reason. This is a "happy" piece of equipment. Fast with a beautiful sparkle and tone. Absolutely quiet as advertised. The Ultrapath seems just a little too much under control (slightly "grumpy" if you will). One thing I noticed is that the difference in sound between my vinal and CD equipment is much more obvious. I attribute it to extremely low distortion. I listened for two days straight nearly all day!
I built my Aikido with 4 octal and 4 9 pin sockets. Right now I am listening to 6SN7GT into 6BX7GT and I haven't even got around to wireing up for the 9 pins yet. I have enough sockets to even try some of my singles. What does a 12A4 input sound like? By the way. visit the Tubecad main page for some other great reads and ideas. I'm going back to listen to my records which I now like just a little bit better than my CD's....maybe.
Follow Ups:
Bruce, I want to respond to your comment that the circuit gives more than reduced power supply noise, but also seems to rid the output of power supply weirdness. In a somewhat simplified view of PS operation, I see three sources of PS noise/weirdness: 1) mains noise not removed by PS filtering/regulation; 2) PS hum and switching noise; 3) dynamic non-linearity.The 3rd form of PS noise involves all sorts of variables from ringing to noise generated from the dielectric absorption of the inductor winding dielectric and of the supply capacitors. Audiophiles spend many $$ tweaking PS components to reduce the awful sonic contribution of these noise sources. I'm not surprised you hear a magical quality listening to the Aikido amp---if the circuit does reduce PS noise (all three varieities), what's left is that magical thing called the amplified signal.
Hi Bruce, have you a schematic you might send me so I can study the circuit?
Tom
Go to www.tubecad.com. John Broskie has posted lots of Aikido schematic variations. This is not a single schematic, but a method of cancelling power supply nasties. More info to come on this site.
I'm getting the resistors for the Aikido tomorrow...was planning this before I read your post!...really did ;-)I have never tried a lot of schematics...and I should have...but I am very happy with my Raleigh Audio line stage. But...the itch to build and compare is always there.....so I have to try the BDT preamp and the Aikido soon.
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