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PostPosted: 12 Jan 2009, 16:36 
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Joined: 14 Oct 2008, 17:35
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Location: Dartmouth, Nova Scotia
This preamp is a stereo unit, and yes I did try it with headphones but it did not drive them very well (obviously!). This entire unit can be put into a single chassis with no problems what so ever, and actually I recommend going this route for those wishing to build this preamp because you will have lower noise in doing so.

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PostPosted: 01 Feb 2009, 21:55 
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Joined: 14 Nov 2008, 09:09
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Hi Alan - would these 12V transformers work for the preamp power supply:
http://www.minute-man.com/acatalog/12V_ ... rmers.html

I'm not understanding which 2 should be used for wiring them back to back for the power supply --

Or, if you think it would be easier, which 120V power transformer would work? I'm not understanding all of the variables/options on the Hammond web site --

Thanks for your help--
Reed


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PostPosted: 02 Feb 2009, 13:27 
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I would recommend using a 500mA and an 300mA for the HV supply, but I would still recommend a single 262D12 Hammond transformer, it has a 120V 53mA winding for the HV and a 12.6V 450mA winding for the tube filaments, and they cost $25-$30.

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PostPosted: 05 Apr 2009, 14:51 
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I was just wondering, Is the variable resistor and LED a required component or is it just an indicator that I can leave out?


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PostPosted: 05 Apr 2009, 17:38 
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I would like to make this very clear.... It has nothing to do with the audio circuit itself!! it is an indicator!!!!!! :mad: The pot is there to vary the brightness, and the resistor is there so I don't blow up the LED. ;)

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PostPosted: 06 May 2009, 21:55 
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Is the 262D12 Hammond transformer discontinued? cant seem to find it anywhere?


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PostPosted: 08 May 2009, 10:26 
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It shouldn't be, I looked on the Hammond website and it is still listed. I would call them or email them to find out, you might be able to order straight from them if you cant find it any where.

Actually, Parts Connection has it for $28.93 : http://www.partsconnexion.com/t/catalog ... rmers.html

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PostPosted: 15 May 2009, 13:16 
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OK, so I'm a doofus. I want to build this but I'm somewhat new with tubes. I see a schematic for a mono pre-amp or half a stereo pre-amp. Looks pretty easy, but I'd like to do a tube rectifier. Maybe a 6x4? Would this work with a 120V PS? Or does a 6x4 need more voltage to work?

what I'd like to have is a tube pre-amp with exposed tubes and an ipod dock.

EDIT: I want it to have RCA inputs and an ipod dock. It'll be in a bigger box because I want to use a remote control attenuator. I see these are now commonly available. So, the attenuator would be on the RCA input, but I'm not sure how to wire in the ipod dock. would there have to be switch in the input ckt to keep the two inputs from interfering with each other or feeding current into the output ckts of each other? So both sources would be wired to the switch which would feed into the attenuator?


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PostPosted: 16 May 2009, 13:04 
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Little slow around here on the weekends?

Anyway, why not use this gizmo for the ipod dock? mount it in the top, plug in the mini-jack, cut off the cable wherever I need to.

see: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0309734471


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PostPosted: 16 May 2009, 20:39 
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Sorry about the slow response, indeed the weekends can be a bit busy, ither working on a project or because it is spring there are gardening tools that need sharpening and lawns that need mowing.... anyways, if you want to use a rectifier tube on this preamp, you will also need two 4007 diodes to make a full wave bridge to get 120-150V.

use my 25EH5 amplifier schematic as a reference: viewtopic.php?f=9&t=216

As for the ipod dock, I have never actually tried wiring one up to a preamp permanently, I have used the output jack on the one that I have, but that is all. I do how ever have plans to make a Moebius 6AQ5 preamp with a docking bay built in, but until I finnish other projects It is on hold.

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