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DHA - DI


DHA
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I have just received a bluk order of VT1-EQ PCBs and as there is a breakout bit on the board for the valve to sit in I put a spare DI circuit on there. So instead of bunging all the spare bits of PCB in the bin I can now offer a balanced DI pedal.

It will be an XLR balanced DI (same design as the EQ) with a 3 position ground switch - ground, Float and Ploat, instrument in and out on 1/4" jacks (out is just linked to the in), DI level pot with switch for on/off (also switches on via the i/p jack), on led, battery and 9-12VDC centre negative power connector in a 110mm x 60mm x 50mm (with the knob) box.

This is solid state design so there is no valve signal path unlike my other designs, it is not designed to colour the tone in anyway.

£30 + £3.50 P&P to BC forum members.

Dave

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[quote name='DHA' post='445221' date='Mar 25 2009, 06:07 PM']Float disconnects the ground completely and Ploat connects to ground via 10R resistor and 100nF cap in parallel.[/quote]

Thanks for the explanation. Next question: what's the advantage of Ploat and when would you use it?

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[quote name='The Funk' post='445239' date='Mar 25 2009, 06:21 PM']Thanks for the explanation. Next question: what's the advantage of Ploat and when would you use it?[/quote]

Not really sure what the advantage is to be honest! But all high end DI's have this and it's simple to do so I did it. With Ploat you still have a ground connection via the 10R resistor and 99 times out of 100 this will fix ground loop hums but when it does not the ground Float will do the job.

I am sure one of the brighter BC members will know why and will be along soon :)

It's Pin 1 on the XLR that is connected to ground or not via the ground lift switch and not to be confused with the cable screen that is always connected to ground.

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[quote name='DHA' post='445251' date='Mar 25 2009, 06:29 PM']Not really sure what the advantage is to be honest! But all high end DI's have this and it's simple to do so I did it. With Ploat you still have a ground connection via the 10R resistor and 99 times out of 100 this will fix ground loop hums but when it does not the ground Float will do the job.

I am sure one of the brighter BC members will know why and will be along soon :)

It's Pin 1 on the XLR that is connected to ground or not via the ground lift switch and not to be confused with the cable screen that is always connected to ground.[/quote]

Thanks for that! I don't need the science part, just what it does. Sounds like a very useful feature!

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