Aikido pre, Glassware PS-1, let's hope this works . . .

mike_p

Downhome Upstate
I just sold my current linestage; its going out the door to the purchaser tomorrow. It's replacement will probably get here in about a month (an Audio by Van Alstine FET Valve CF, in the process of being assembled).

I finally got around to building this, because at this point I have no choice if I want to listen to some tunes. I'm glad I had Front Panel Express fabricate the faceplate. Has anyone else sat on a project like this for a year besides me?

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It's a linestage, a preamp sans phono stage. John Broskie designed both the linestage and PSU circuits (separately) and writes about tube audio electronics over on the Tube CAD Journal: http://www.tubecad.com/

To support his writing, John offers some really well-made PCBs (with or without components) implementing some of the ideas he writes about, including the Aikido circuit. The Aikido, named for the principle in that art of using the opponents force against him, is a cascaded self-regulating triode circuit topology. Here's a link: http://glass-ware.stores.yahoo.net/ailiam.html

When you build one of John's circuits, even with supplied components, you have to make some important choices of components to leave in, or leave out, values, etc. Those choices can have significant consequences for the end result. So in that way, its different from kit building, at least in my experience.

For example, in the linestage shown above, the Aikido circuit topology will work with any triodes, so long as the top and bottom tubes in the input stage are the same, and ditto for the top and bottom tubes in the output stage. So, you have to determine what are you aiming for in terms of input stage gain and output stage impedance. The choice of tubes includes a choice of operating point, the B+ the plates will see, and the choice of cathode resistor.

The Aikido linestage board has a B+ smoothing filter, but no PSU. So you have power supply choices to make to match your tube choices: solid state, or tube? Regulated or unregulated? If solid state, full-wave bridge rectifier or full-wave voltage doubler? 12.6 v or 12 v or 6.3 v or 6v heater supply? Reference the heater supply to a fraction of the B+ supply, or let it float in reference to ground? Transformer choices for the above?

Due to the choices you make when implementing one of these circuit designs, there is an opportunity to learn more than when building a kit (although that's a lot of fun, too).
 
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As to choices, ditto for the controls. This one uses a hybrid ladder/series attenuator with 36 1.5dB steps. The center control establishes the main volume setting for both left and right channels, and the flanking fine adjustment controls act both to implement the 36-step routine and as a balance control. I used Vishay Dale 1% precision metal film resistors for this one. Next time I think I'll try PRP resistors instead. The linestage has a mono/stereo control, something I find very helpful. And you can choose one of 2 coupling capacitors, both to affect tone and set the bass corner frequency.
 
Nice work!

I have a friend on AC who has built several of the Aikido's and he raves over them. I need to visit him for a listen.
 
I built an Aikido line stage with a regulated SS dual PS. And added a phono stage as well. Very quiet and clear sounding. I settled on RCA 12au7 clear tops. The phono uses two 12ay7's. I really like the Aikido. I stuffed mine into a reproduction PAS chassis and had a custom face plate made. No tone controls needed. I hope you like yours as much as I do mine. Nice work. :thumbsup:
 
Very nice! Its fun building with all new parts and chassis. Makes for nice clean wiring. Even though I could run my amp without a line stage, I like what the aikido brings to the party.
 

Mike,
Great looking unit!
Would you mind sharing BOM parts list you used to build this preamp?
I've been looking to build all tube system to replace my current SS Pioneer SX-1280 to use with my stacked OLA speakers.
I don't have the electronic knowledge most of you guys have but have fairly good soldering and assembly skills as well as a great desire to listen to something different. I feel that my Advents are handcuffed with solid state sound.
 
Mike,
Great looking unit!
Would you mind sharing BOM parts list you used to build this preamp?
I've been looking to build all tube system to replace my current SS Pioneer SX-1280 to use with my stacked OLA speakers.
I don't have the electronic knowledge most of you guys have but have fairly good soldering and assembly skills as well as a great desire to listen to something different. I feel that my Advents are handcuffed with solid state sound.

Will send PM
 
Necrothread.

Mike, I'd be interested in your BOM and your FPE file (if your willing to share because I suck at FPE designing) for this as well if you still have it? I've had my noval pcb with PS-1 sitting in a box for nearly 5 years now. Really need to get it done.
 
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