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Old 28th May 2013, 02:06 AM   #41
Einric is offline Einric  United States
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The ground could go to the chassis, wherever your "Star Ground" point is.
The biggest benefits are that you could keep the mess of wires to near nothing & you don't have to worry about your inputs needing to stay away from noisy stuff.
I believe that it also gives you 4 inputs instead of the three you asked for.
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Old 28th May 2013, 02:15 AM   #42
Sprags is offline Sprags  United States
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Thank you for the Bottlehead suggestion...I'll look into it. I think I'd really prefer the Akido preamp though. I'm beginning to understand conceptually how everything works. I think I'll be ok with tackling the Akido 12 Vac project though. According to a forum member I already have a preamp based on the Akido design. I bought it completely built. It has a slight hum and to be honest the PCB doesn't look as well made as John Broskie's. I'm really curious about the builders claims that say its better than a lot of the multi-thousand dollar brand name preamps out there. I'd like to see if this kit can produce a preamp that sounds as good or better than the one I already have. If not but it sounds decent, I'll delegate it to my secondary system. If it does sound as good I may still do that and perhaps attempt the 5687 All-In-One kit and hopefully use that with my main system.

As for the selector relay I like the wire management explanation.

Last edited by Sprags; 28th May 2013 at 02:19 AM.
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Old 20th July 2013, 06:51 AM   #43
Sprags is offline Sprags  United States
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I started this thread during a time when I was laid off but still interested in building a kit and the Akido 12Vac kit seems like it is what I want not as a way of learning about electronics but also as a way of adding a nice piece of audio equipment to my system. I think I'm about to start a new job in a few weeks at the latest and if so will be able purchase this kit along with everything else needed to put everything together.

I still have questions and appreciate the feedback.

Yet one more question...
Is there a chance that after assembling this kit that there will be audible hum...either electrical or mechanical? Can someone tell me what are the main causes of electronic hum in electronics? I understand mechanical hum can come from either a poorly fastened transformer to he chassis or from the transformer itself. But I don't understand what can cause electronic hum that is audible through the speakers.

I'm going have review this whole thread but I'm pretty sure in addition to the Akido 12Vac I'm going to use a toroidal transformer as a power supply and a pre wired board for the switches and controls to simplified the construction.

Thank you again for the assistance.
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Old 20th July 2013, 04:34 PM   #44
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Hum can be caused by insufficient power supply filtering, poor physical layout, ground loops (internal and external), AC filament supply, among other things. Use a large case so you can keep the Aikido boards away from the power supply area. Internal shielding can help as well as a star ground.

John
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Old 20th July 2013, 05:24 PM   #45
Sprags is offline Sprags  United States
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Thank you. A larger chassis, in fact, is my choice, just to make assembly easier and less likely to become confused by wires becoming hard to trace. And as you say it may also make it easier to shield components. In my web surfing I found a chassis and ill have to go through my bookmarks to track it down again. If I remember it is extruded aluminum with heat sinks and reasonably priced...around $200. I'll probably used that face plate company to fabricate one to my design. I think I'll have a Bridgeport to use to drill or bore or machine any openings I'll need soon as well.....Thanks..
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Old 20th July 2013, 07:13 PM   #46
Einric is offline Einric  United States
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Keep you small signal wires as far away from AC sources as you can and shield them.
The under side of my aikido is pretty messy with my I/O wiring just hanging around free.
But, all of my I/O wiring is a few inches from the HV AC lines except for at the chassis RCA's where there is 1" space from them.
My Aikido is as quiet as the tubes I put in it.
There is NO hum at all and Broskie runs DC heaters and DC B+ so there is very little chance of noise from there.
So long as you take your "Star" ground directly to your chassis ground and take all other grounds to that star ground point then you should be very well off.
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Old 21st July 2013, 08:51 PM   #47
cjkpkg is offline cjkpkg  United States
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The aikido is dead quiet when wired properly.

Things that will help:
DC heaters
Shunt the ground with a small value resistor and film cap
Star ground...run a discrete wire for each hookup to the star
Shield your transformer...if supplied with a shield wire try different points within the build to tie it to. For whatever reason my last build I had to tie the xformer shield to the heater center tap on the PSU.
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Old 21st July 2013, 10:25 PM   #48
AJT is offline AJT  Philippines
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Default Russian 6H8C and 6H30 aikido

Click the image to open in full size.
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Old 22nd July 2013, 01:01 AM   #49
farhun is offline farhun  United States
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AJT, what kind of capacitors are those in the picture?
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Old 22nd July 2013, 03:22 AM   #50
AJT is offline AJT  Philippines
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Quote:
Originally Posted by farhun View Post
AJT, what kind of capacitors are those in the picture?
Nippon Chemicon, CE series 105*Cm 1100ufd/300volts...
harvested from smps psu's...
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