Can I use a 01A in a headphone amp? - diyAudio
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Old 25th April 2006, 02:55 PM   #1
sbelyo is offline sbelyo  United States
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Default Can I use a 01A in a headphone amp?

I love those old globe type tubes. I was wondering if there was a schematic out there using a 01A and other tubes that could power headphones. I'm still learning how tubes should be used, so I'm guessing I'll need an output transformer?
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Old 25th April 2006, 03:52 PM   #2
Rocky is offline Rocky  Norway
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01A has a high Rp, about 10K IIRC, and very low current handling, in the area of 3mA... I don't think you easily can power headphones with it. 12A has same gain, half the Rp, and double current handling (7.6mA).. It looks like the 01A does and sounds like an angel.. you might be able to power headphones with that tube, loaded with something like a 20K:600R preamp OPT..

EDIT: high impedance headphones...
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Old 25th April 2006, 05:02 PM   #3
sbelyo is offline sbelyo  United States
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I see.... I'm still at the point of need someone's schematic of a proven design to get anything to work.
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Old 25th April 2006, 06:19 PM   #4
Rocky is offline Rocky  Norway
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For inspiration, take a look at "The Journey" preamp by Bjørn Aaholm at http://vinyl.and.triodes.net/. It is similar to what you are trying to do exept you want lower output impedance.

A problem with only one stage DHT is getting enough gain, as you will have to trade it to get low enough output impedance to drive your headphones. "DHTRob" has an unusual twist on an headphone amp combining a DHT and a IDHT without output transformers, at http://www.dhtrob.com/projecten/hfdt...tage_1_en.htm. Could be worth a look.

Another good source for headphone amplifiers using tubes is www.headwize.com, but I don't think there are any DHT projects at that site.

Have a look around. Possebilities are many when power requirements are modest. I built a 700mW DHT amp very recently, 12A driving 71A, my first DHT amp www.vt52.com was perhaps the biggest source of inspiration for me.
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Old 25th April 2006, 08:06 PM   #5
sbelyo is offline sbelyo  United States
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Quote:
Originally posted by Rocky
For inspiration, take a look at "The Journey" preamp by Bjørn Aaholm at http://vinyl.and.triodes.net/. It is similar to what you are trying to do exept you want lower output impedance.

Thanks for finding this

Quote:
Originally posted by Rocky A problem with only one stage DHT is getting enough gain, as you will have to trade it to get low enough output impedance to drive your headphones. "DHTRob" has an unusual twist on an headphone amp combining a DHT and a IDHT without output transformers, at http://www.dhtrob.com/projecten/hfdt...tage_1_en.htm. Could be worth a look.
I'm not to worried about gain as my sources are pretty good. I'll look into this one

Quote:
Originally posted by Rocky Another good source for headphone amplifiers using tubes is www.headwize.com, but I don't think there are any DHT projects at that site.
I'm on that site, as well as headfi. You're right, I don't think there are any DHT projects. I'm building this one http://headwize.com/projects/showfil...aarde1_prj.htm
Followed by this one
http://headwize.com/projects/showfil...train1_prj.htm

They're both OTL and low cost. I figure once I get them working I can move up to bigger and better things

Quote:
Originally posted by Rocky Have a look around. Possebilities are many when power requirements are modest. I built a 700mW DHT amp very recently, 12A driving 71A, my first DHT amp www.vt52.com was perhaps the biggest source of inspiration for me.
I saw that amp... I liked the look of it. It's actually what I want to try in the next few projects
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Old 26th April 2006, 12:19 AM   #6
arnoldc is offline arnoldc  Philippines
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I have a NOS pair of 01A myself and have not built any circuit using it.

I wanted to use the pair as a preamp then, with Altec 15095 mic-step up (for more gain) -> 01A -> 12B4A CF for low Zout.

It never materialized, as I used the 12B4 on its own in a preamp, and loved it.
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Old 26th April 2006, 03:10 AM   #7
sbelyo is offline sbelyo  United States
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I have a 12B4A that I'm not using. Maybe I could do something with that. What do people use the 01A for usually?
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Old 26th April 2006, 04:12 AM   #8
arnoldc is offline arnoldc  Philippines
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I am as confused as you as to where to use my 01A
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Old 26th April 2006, 04:14 AM   #9
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Quote:
Originally posted by sbelyo
I have a 12B4A that I'm not using. Maybe I could do something with that. What do people use the 01A for usually?
It's a small signal, voltage amplifier type. It was also used as a detector in AM receivers.
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Old 26th April 2006, 04:35 AM   #10
arnoldc is offline arnoldc  Philippines
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I've seen on the net a couple of implementations using 01A to drive a 71A.

I planned on running the 01A at 100V/3.5mA/4V bias through a 6922 CF as well for a preamp.

I wanted to use this as a preamp, but I believe it will be as difficult as the 26 as far noise is concerned.

Joel Tunnah has an amp that uses 01A as drivers at 135V/3mA/9V bias via batteries.
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