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  #1  
Old 28th August 2006, 12:32 PM
Claes
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Default HD83, how to use low and high impedance cans?

Hi, I have built a hd83 some years ago.
I have been using it with a hd600,so it is wired to the
above 250 ohm config.
Now I have bought a pair of sony mdr cd 3000 and
they are 32 ohms.

I want to use both phones with the amp, not at the same time though.

How do I add that function to the amp in the easiest way?
I can think of two ways:

1. Have two headphone sockets on the front, then amp is constantly
wired for two outputs, not sure that is possible, do
not have the schemas here, they are in Ireland, I am in sweden.
Can I wire the output transformers so they are contstanly set up to accept
both 32 ohm and 300 ohm cans, through two outputs at the front?

2. I add a switch, so I can switch the config of the transformers, so I can
switch between 32 and 300 ohm.

since I do not have the schemas here, can someone advise me?
Or point me to schemas?

Cheers,

Claes.
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  #2  
Old 28th August 2006, 12:45 PM
Mike G Mike G is offline
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Default Re: HD83, how to use low and high impedance cans?

Hi,

I'm not sure if this will be of use, but if you take a look at the World Designs amplifier kits, and check out the technical information for the HD83 II, you can see a circuit diagram.

I know this is for the mark two version, but I think it was the same circuit for both (just the layout and casework were revised in the later model).

http://www.world-designs.co.uk/acatalog/AmpKits.html

Regards

Mike.
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  #3  
Old 28th August 2006, 01:17 PM
Claes
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Default Re: HD83, how to use low and high impedance cans?

Thanks for the link but that does not solve the problem.
I need the page that has the "wiring" info for the output transformers, they show how to wire the transformer for different impedance cans.

Thanks anyway.
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  #4  
Old 28th August 2006, 02:31 PM
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Little Mick Little Mick is offline
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Default Re: HD83, how to use low and high impedance cans?

Hi

For 16-50 ohms looks like all the secondary are connected in parallel i.e.

0 ohms to blue 1, blue 2, blue 3, blue 4.

16-50 ohms to purple 1, purple 2, purple 3, purple4.


Regards
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  #5  
Old 28th August 2006, 03:14 PM
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John T John T is offline
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Location: Cardiff. UK.
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Default Re: HD83, how to use low and high impedance cans?

Is this what you're looking for?

P10.jpg

P11.jpg

Regards,

John.
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  #6  
Old 28th August 2006, 04:57 PM
Claes
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Default Re: HD83, how to use low and high impedance cans?

Hey, you da man
Now I just need to figure out how to solve my little problem,
anyone have any ideas if you understand my original description?

Cheers,

Oh btw, can one navigate to these from the world design site as it is now?
I could not find those pics from the HD83 amp II page.
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  #7  
Old 28th August 2006, 05:04 PM
Claes
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Default Re: HD83, how to use low and high impedance cans?

Those pics are a little hard to read, you would not happen to have higher resolution images that are easier to read?

Thanks.
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  #8  
Old 28th August 2006, 06:00 PM
Claes
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Default Re: HD83, how to use low and high impedance cans?

Hmm, when looking at it it looks a bit messy to acchieve.
250 ohm setting, every thing is in parallell.
16-50 ohm setting, everything is in series.

Not very easy to acchieve.

Hmm, what am I supposed to do if I have more than one can that I wanna use with a HD 83?
I guess that I could rewire the whole thing for the 16-50 ohm setting, then
just add a series resistor when using the hd600, of about 220 ohms.
Is that the best way to do it perhaps?

Any ideas?
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  #9  
Old 28th August 2006, 06:14 PM
colin.hepburn colin.hepburn is offline
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Default Re: HD83, how to use low and high impedance cans?

This May help you its for different Amp but maybe of uses

http://www.world-designs.co.uk/forum...1&d=1156781561
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Last edited by colin.hepburn; 13th April 2007 at 10:02 PM.
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  #10  
Old 28th August 2006, 07:17 PM
Claes
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Default Re: HD83, how to use low and high impedance cans?

I got it backwords, what I meant is of course, keep wiring as it is, just use a series resistor of 220 ohm for my 32 ohm cans then.

Is that a good solution according to you guys here?

Cheers,
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