WD Pre 4 - World-Designs-Forum

david.rogers · #1 29th March 2019, 01:51 PM

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

pre65 · #2 29th March 2019, 02:02 PM

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

http://www.world-designs.co.uk/pre%20amps.htm

John Caswell · #3 29th March 2019, 07:01 PM

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

DejanM · #4 18th July 2019, 06:30 AM

Hi,

What is the output impedance of Pre4 ?

bob orbell · #5 18th July 2019, 06:44 AM

The same as the Pre III. Bob

John Caswell · #6 18th July 2019, 08:48 AM

About 10R, so will drive most things effortlessly.

John

MrKettle · #7 18th July 2019, 10:53 PM

So presumably quite a big trafo ratio to step down two gain stages to 5dB?

bikerhifinut · #8 18th July 2019, 11:50 PM

Quote:

Originally Posted by MrKettle

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.