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  #1  
Old 18th April 2019, 12:53 PM
Matthew Snell Matthew Snell is offline
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Default A new member of the family!

Dear All

Following on from the rave review for Pre4 in Hi-Fi World, we are proud to announce another product launch.

Pre3 CF is a cathode follower preamp with a gain of approx 0.95 and it is powered by PSU3. Many members here have successfully converted their PreIIs to a very similar circuit. Here we have a very nicely designed and manufactured PCB (with lots of room for upgrading components) incorporated into the existing Pre3 chassis and, of course, utilising our RelayBoard source switching. There is also an optional CCS circuit allowing for long leads to the power amp which, for those averse to all things solid state, can be switched “out” by means of internal PCB links. We think Pre3 CF will be of particular interest to people who already run Phono3 but haven’t yet invested in a preamplifier, as well as to new customers.

For further details have a look on the website or be in touch. You can - as always with World Designs kits - confidently recommend it to your friends or family!

Regards,

Matthew
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  #2  
Old 18th April 2019, 09:39 PM
bikerhifinut bikerhifinut is offline
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Location: Penrith, Cumbria
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Default Re: A new member of the family!

Don't let it be said you don't take note of what has been posted here and other places matthew!
I'm intrigued by the idea of a CCS on the cathode, I imagine its a similar idea to what Bob Orbell and I have done with WD preamps, except we used a triode active load on the cathode.
I have to say I don't think theres any significant difference between a standard "Bootstrapped" Cathode follower design and the active load CF design I currently have in terms of what comes out of the output sockets. Nice to have the choice though.
Can you clarify a point Matthew? would I be correct in thinking the same CF board could be used in pre4 in place of the transformer output circuit? I have to say that the WD transformer pre I have recently built after having the bits lying around for ages sounds gobsmackingly good albeit I had to tweak the gain down a tad using JC's advice.

Good luck and may you have good sales.

Andy.
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  #3  
Old 19th April 2019, 01:59 PM
bob orbell bob orbell is offline
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Default Re: A new member of the family!

Is there any possibility of a picture Matthew. Bob
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  #4  
Old 19th April 2019, 02:45 PM
Richard Richard is offline
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Default Re: A new member of the family!

Pic and a bit more about Pre4 and Pre3CF here, http://www.world-designs.co.uk/pre%20amps.htm
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Old 19th April 2019, 07:51 PM
bob orbell bob orbell is offline
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Default Re: A new member of the family!

Thanks Richard, I looked at that, but was interested in the internals and the lay out. Maybe Matthew can post something. Bob
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  #6  
Old 20th April 2019, 11:12 AM
Matthew Snell Matthew Snell is offline
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Default Re: A new member of the family!

Hi All

Both Pre3 CF and Pre4 PCBs have been designed to mount on standoffs fitted to the slots in the base of our chassis - there's a bit of latitude for positioning fore-and-aft. PCB dimensions are 110x159 with mounting points centred on 96 and 147. So either board can go into Pre3 and Pre4 cases (it was deliberate!) We tried to think of everything. Lots of double landings and room for upgrade components. Ground planes. Double sided plated through and manufactured to spec, rather than price.

I have attached photos of both preamps in "standard" format and hope this goes some way to showing how things are laid out. I am happy to do some more pics if people want them - let me know! And feel free to be in touch directly.

Thank you for the encouragement.

Matthew
Attached Images
File Type: jpg Pre4.jpg (69.9 KB, 75 views)
File Type: jpg Pre3 CF.jpg (55.1 KB, 65 views)
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  #7  
Old 20th April 2019, 01:26 PM
bob orbell bob orbell is offline
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Default Re: A new member of the family!

Thanks Matthew, they both look very promising. Bob
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