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Old 14th July 2006, 12:20 AM   #1
jarthel is offline jarthel  Australia
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Default aikido and output transformer

I am thinking of building one of this: http://www.tubecad.com/2006/04/27/ai..._amplifier.png

I am wondering if the output caps can be omitted if I use an output transformer.

Thanks for the help.
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Old 14th July 2006, 02:00 AM   #2
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Default Re: aikido and output transformer

Quote:
Originally posted by jarthel
I am wondering if the output caps can be omitted if I use an output transformer.
Yes. Proponents of iron for DC blocking claim fine iron beats the sound of fine caps. Can't verify that position yet but I plan to try it out with my Aikido boards.
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Old 14th July 2006, 02:03 AM   #3
jarthel is offline jarthel  Australia
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Default Re: Re: aikido and output transformer

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Originally posted by leadbelly


Yes. Proponents of iron for DC blocking claim fine iron beats the sound of fine caps. Can't verify that position yet but I plan to try it out with my Aikido boards.

can you suggest an output transformer from the hammond range that is suitable for the aikido headphone amp? thank you
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Old 15th July 2006, 05:43 PM   #4
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Can't see how you could use an output transformer with the aikido circuit other than in a parafeed (capacitor coupled) arrangement which would be a bit pointless in this case since you would still need the output caps
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Old 15th July 2006, 06:42 PM   #5
Tweeker is offline Tweeker  United States
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Requires an airgapped OPT, so Im not sure low end iron will beat capacitor coupling of similar cost. Consider using oil motor run capacitors for budget coupling caps as another alternative. From correspondence:
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File Type: jpg transformer akido.jpg (21.1 KB, 773 views)
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Old 16th July 2006, 03:17 AM   #6
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Thanks for correcting me. I was thinking of the attached schematic and thought that the capacitor was only needed for DC blocking for the High-Z output. I also thought non-airgapped transformers were suitable for this service if the DC current was low enough, but it sounds like that's not the case.
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Old 16th July 2006, 06:07 AM   #7
Tweeker is offline Tweeker  United States
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Fine iron may well beat fine caps, but, there are many fine iron proponents who dont feel Hammond quite qualifies. Also, finding an OPT whos DCR will set the bias for an optimal operating point may be tricky.
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Old 16th July 2006, 07:09 AM   #8
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This one looks useful.
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Old 16th July 2006, 06:03 PM   #9
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Quote:
Originally posted by Geek
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You guys are confusing the bleep out of me. Why would you put in a 1:1 transformer if you still need the cap to block DC? I could see using the 10K/150 or 10K/600 to drive low-Z headphones.
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Old 18th July 2006, 10:42 AM   #10
zix is offline zix  Sweden
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I canīt do the math, but to my eye the circuit first published would seem to work nicely with a Lundahl 1660SE/18mA. Is there something that would make this a bad choice in the Aikido output stage?
Edit: and the second one would do witout a coupling cap, if you don't need the high z output.
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