Dual Class-A Line and Headphone Output Board Documents

Construction information for DIY projects, including the MS Mid Side Matrix, Elliptic Equalizer, Mastering Console, Phono Transfer System, Insert Switcher and the Dual Class-A Amplifier. You can post your baby pictures here.
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JR.
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by JR. » Thu Mar 24, 2016 9:56 am

Gold wrote:
ricardo wrote:I've done experiments with heatpipes
I had never heard of a heat pipe. A quick search turns up a tube filled with liquid. I think a home brew heat pipe is asking for trouble. I see leaks. This is only going to sit on my bench and be dragged around for troubleshooting if needed. Close enough for me.
You can buy sealed heat pipes, but over kill for your project. (I never used one).

JR
[edit] not as expensive as I remember. here's one for < $4 in onseys.
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http://www.digikey.com/product-detail/e ... ND/5049709 [/edit]

ricardo
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by ricardo » Fri Mar 25, 2016 4:44 am

JR. wrote:You can buy sealed heat pipes, but over kill for your project. (I never used one).

[edit] not as expensive as I remember. here's one for < $4 in onseys.
Image
http://www.digikey.com/product-detail/e ... ND/5049709 [/edit]
:o :D

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mediatechnology
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by mediatechnology » Fri Mar 25, 2016 9:28 am

A quick search turns up a tube filled with liquid.
Or a tube emptying liquid...

Image

Their image not mine. :lol:
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JR.
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by JR. » Fri Mar 25, 2016 10:04 am

mediatechnology wrote:
A quick search turns up a tube filled with liquid.
Or a tube emptying liquid...

Image

Their image not mine. :lol:
I actually considered water cooling big power amps, but only momentarily.

Mixing water and power amps is never a good idea for reliability.

JR

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Re: Dual Class-A Line and Headphone Output Board Documents

Post by emrr » Fri Mar 25, 2016 11:54 pm

Yeah, they stopped building water cooled transmitters a long time ago, I think. Those water cooled Western Electric pre-war 5kW jobs come to mind, big as a small house.
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by brianroth » Sat Mar 26, 2016 8:37 am

Years ago I saw a Cray computer which was on display at the Smithsonian Air and Space museum. Various access panels were open, and the multiple PSU units in the base of the monster were all interconnected with copper water lines!

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Gold
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by Gold » Tue Mar 29, 2016 9:05 pm

I got the replacement TKD pots in. They didn't have good 10K pots so I went with 50k. Seems okay. It will be a whole new world with headphones in the studio.

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mediatechnology
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by mediatechnology » Wed Mar 30, 2016 7:33 am

That's beautiful work!
Where did you get those pots?

FWIW I noticed that Parts Express are stocking the Alps RK271(?) series: http://www.parts-express.com/alps-10kax ... t--023-204
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Re: Dual Class-A Line and Headphone Output Board Documents

Post by Gold » Wed Mar 30, 2016 11:12 am

I got them from Parts Connection. They were the only place I could find that had the TKD. They are very nice. The channel matching is excellent and they feel expensive. If I had known the new Alps were 27mm square and would fit in a 1RU case I would have used those. The TKD are a good alternative to a P&G RF15. Compared to those they are cheap.

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Re: Dual Class-A Line and Headphone Output Board Documents

Post by Gold » Wed Mar 30, 2016 2:41 pm

I'm having a bit of an issue. With the 50k audio taper pot at the top of the throw (all the way up) I get distortion during the first 30º or so of rotation. It sounds like a scratchy pot but sounds the same on both channels of one pot and the same on both channels of the other pot. The buildout resistor is 22Ω

I thought I'd try to look at it on the scope. With a clip lead from the probe I attached scope ground to audio common at the TRS connector. The tip of the probe went to signal. With no headphones attached everything looks clean. With headphone attached the signal looks like a distorted mess no matter the position of the pot. I haven't measured distortion with the phones attached but that seems like the next logical step.

I have a feeling I'm dealing with more than one issue. Any ideas?

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