joethearachnid
Been here a while!
Old head on young shoulders.
Posts: 380
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Post by joethearachnid on Dec 6, 2011 1:06:59 GMT
You could try an Oatley K272A ( secure.oatleyelectronics.com//product_info.php?products_id=885&osCsid=f4e5c000e0590d5bef37513e592a8de1) It's not a perfect amp for a variety of reasons, but it's a dead cheap kit and gives you a taste of tubes (you will need to ship it from Australia, but as I recall their international rates are very reasonable). You'll need a box, a volume control, some wiring and various fittings, but it shouldn't come to more than about £30. I managed to build mine for about £25, though I used an old metal cigarette box for a case and had my brother bring the kit back with him from Australia so no shipping. It is battery powered, and given the sensitivity of the tubes a PSU isn't really usable unless you have a silent linear PSU to hand. Changing out the batteries can be a pain, so don't go for it if that's a dealbreaker. The tubes are also incredibly microphonic and need plenty of damping. But hey, it's cheap and has tubes! On your BT928, I'm nowhere near an expert like some of the fellows on here, but I might think about shortening those wires to the large capacitor, since they'll be quite prone to interference. Possibly. -JoetheArachnid
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joethearachnid
Been here a while!
Old head on young shoulders.
Posts: 380
|
Post by joethearachnid on Dec 6, 2011 20:50:45 GMT
I don't think that generally there's not a lot of difference between a headphone amp and a preamp circuit-wise, so often amps are used for both. I think that some headphone amps have more output power than preamps. In terms of the K272A, the IC it uses is a specific headphone driver chip and the circuit is optimised for (low impedance) headphones.
-JoetheArachnid
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Deleted
Deleted Member
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Post by Deleted on Dec 8, 2011 4:54:20 GMT
How about the 2 x 9volt battery operated headphone amplifier from Elektor Jan.2011 ? The PCB is available from Elektor. Alex Attachments:
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