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Old 20th July 2008, 12:34 PM   #1
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Default Building a Aikido preamplifier

Hi!

I have built some tube amplifiers, so now I want to build a preamplifier!
Preamplifier and linestage is the same thing, right?

This is what I am looking for:
*Low Distortion
*Low output impedance

Then I read about the Aikido

http://www.tubecad.com/2004/blog0011.htm
http://www.tubecad.com/2005/January/blog0030.htm

So I started with the enclosure:
It's a modified printerswitch in aluminium

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

The tubes are 6N1P:s and 5687:s!
But a friend told me, he had bought pcb:s and in the documentation there was another shematic, not the one I found. He is using the same tubes...
His schematic was called "Revision A Line Amplifier" It was a bit different, so I wonder:

Which schematic shall I use?
I want to use the best one!


ps. I don't want to use pcb:s. That's uncool
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Old 20th July 2008, 01:16 PM   #2
SY is offline SY  United States
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The nice thing about point to point is the ease of moving things around and changing values. So, in a sense, you can find out for yourself. The one modification I'd make is to put a trimpot in the nulling resistor string to adjust out the noise more perfectly- the ratio of the resistors is very sensitive to tube gain.
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Old 20th July 2008, 01:38 PM   #3
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Yeah, point to point is fun!

Does anyone know anything about the different revisions of the Aikido preamplifier?
Any recommendations?
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Old 20th July 2008, 08:34 PM   #4
pchw is offline pchw  United States
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It is different revisions of the pcb, not the circuitry itself.
New pcb provides more flexibilities and hence more "choices" of tubes to be used, for example, but it is still no match to point-to-point :-)
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Old 20th July 2008, 08:50 PM   #5
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Thank you Fred!

So point to point-builders like me simply use the schematic in my previous link
Great!
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Old 21st July 2008, 08:26 AM   #6
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I´ve got the Aikido 9-pin mono boards. They arrived together with the rev. B circuit description (last year). Last time I looked at the Tubecad.com the rev. A description + circuit was still shown. I can´t say exactly which changes were made between rev. A and B.

However, both rev. A and rev. B unfortunately have (small) typos. I have mailed John Broskie about these bot I haven´t heard from him and I think that they have still not been corrected.

If you want a copy of the rev. B then please drop me an email with your private email address and I will send it to you. WARNING! The file is huge (several MB´s - if I remember correctly) beacuse I haven´t found out to use my scanner correctly :-)

I have decided to do the same as SY is suggesting - using a good quality trimpot for optimizing the circuit. I got the inspiration from another thread from this site.

Kind regards

Karsten
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Old 21st July 2008, 08:41 AM   #7
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Thank you! It would be fun to read!

But I cannot email you, because you have disabled that feature!
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Old 21st July 2008, 09:12 AM   #8
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Sorry about that. It should be OK now. Don´t know why this option was disabled - it has been working OK before.

Kind regards

Karsten
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Old 22nd July 2008, 09:39 AM   #9
Brit01 is offline Brit01  United Kingdom
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Hi Olle,

I am in the process of ordering an Aikido too. I'm a total newbie so I'm choosing the Octal PCB. It's going to be

I was going to use a SS SKP Mosfet power amp (100+100W) but now I'm thinking of having a go at a tube power amp at the same time.

What do you think of partnering a dnyakit ST-35 or ST-70 with the Aikido line stage amp?

Cheers,

Chris
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Old 22nd July 2008, 09:45 AM   #10
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In the picture all four tubes seems to very close to each other.
does the distance between tubes (near or far from each other)
matters?
What is the ideal distance between tubes?
regards
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