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  #1  
Old 29th March 2019, 01:51 PM
david.rogers david.rogers is offline
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Default WD Pre 4

Apologies, I'm sure this has been covered mant times, but I've not been on this site for a while. What are the differences between the 3 and 4?

Thanks

David
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  #2  
Old 29th March 2019, 02:02 PM
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pre65 pre65 is offline
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Default Re: WD Pre 4

I was not sure either, so I looked it up.

http://www.world-designs.co.uk/pre%20amps.htm
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  #3  
Old 29th March 2019, 07:01 PM
John Caswell John Caswell is offline
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Default Re: WD Pre 4

Hi all,
Although the pre 4 now has again of +5 unbalanced and +10 Balanced we have incorporated an interstage gain control so you can wind the gain down to suit your system. Obviously if you want to fix the gain you can use fixed Rs as there are PCB pads for them.
There is now available a small PCB to add to the ALPS pot to change it to a shunt volume control if required.
The box is now the same size as the HD83, so more space to use boutique components.
The remote control has a mute position and obviously input select is now electronically controlled as opposed to the original selector switch.
I think general improvements all around.

John
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  #4  
Old 18th July 2019, 07:30 AM
DejanM DejanM is offline
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Default Re: WD Pre 4

Hi,

What is the output impedance of Pre4 ?
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  #5  
Old 18th July 2019, 07:44 AM
bob orbell bob orbell is offline
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Default Re: WD Pre 4

The same as the Pre III. Bob
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  #6  
Old 18th July 2019, 09:48 AM
John Caswell John Caswell is offline
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Default Re: WD Pre 4

About 10R, so will drive most things effortlessly.

John
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  #7  
Old 18th July 2019, 11:53 PM
MrKettle MrKettle is offline
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Default Re: WD Pre 4

So presumably quite a big trafo ratio to step down two gain stages to 5dB?
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  #8  
Old 19th July 2019, 12:50 AM
bikerhifinut bikerhifinut is offline
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Default Re: WD Pre 4

Quote:
Originally Posted by MrKettle View Post
So presumably quite a big trafo ratio to step down two gain stages to 5dB?
er its x 5 gain which is close enough to 15 dB to make no difference, although I think its nearer to x6 in the raw.

yes it has a huge step down ratio which ives it the very low impedance and massive drive for long cables, basically immune to capacitance loading.

A.
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