JFP Based Summing Box

[daArry]

Hey...

Still unsure of which way to go on a summing/mixer box, but was wondering...

Is this schemo (showing a single chan) on the right track hookup wise? I'm aiming for a 16 chan box.

Cheers!

 

[daArry]

woah, a 'look' and a 'good'! :thumb:

have you built a single channel of the INA134 and JFP yet ?

Not yet* - will do soon as tho as I used the INA for the buffer in that LM3886 amp, so can use that to test with these new fellaz:

Much smaller now (30x35mm), with pins on standard 2.54 grid (so easy to use on ie stripboard) - transistors the right way round this time too!

* Just botched the INA buffer with the JFP - works fine :thumb:

Main issue now is the resistor values for the send and pan ckts...

Nice

 

[daArry]

I see that schemo ye - noticed the pan pot in that one seems to be a single gang type - but theres another NYD panpot circuit (which i was using here) that uses a dual gang pot...

 

[NewYorkDave]

You mean this one? :wink:

http://electronicdave.myhosting.net/miscimages/panpot.gif

 

[daArry]

yup - both those in me NYD folder :thumb: :guinness: just need to work out the resistor/pot values based on the Z factors n such...

I think 8 chans per box would be cool, with the ability to cascade multiples...

Hows about using a +/-24V version of this for the inputs instead of the INA and so go fully discreet: http://www.vintagedesign.se/diy/Balanced%20discret%20input.pdf...then perhaps just have a single JFP (or whatever) module for makeup at the end of the summing bus...

 

[NewYorkDave]

First of all, what's a JFP?

I can't keep track of all these model names/numbers.

 

[daArry]

JFP that jfet gain module in pic...

http://home.comcast.net/~markfuksman/hamptone.jpg

 

[daArry]

all line level ere

 

[jstark]

This might be a stupid question, but why do you have a JFP per channel? Isn't this a line-level summing mixer? Don't you just want one make-up gain stage at the end?

 

[Kev]

[quote author="NewYorkDave"]First of all, what's a JFP? ... I can't keep track of all these model names/numbers.[/quote]

:green:

and it doesn't get any easier

a year or so ago when TT was at it's peak my head was about to ... no ... I think it did explode ... TWICE !!

I posted so many detailed answers to so many questions and emails that I found myself answering my own posts with a different answer.
When had so many Group Orders and projects on the go that I think many of the DIY'ers still have their heads down constructing those projects and experimenting with parts.

Some of the people still missing in action have some really GREAT projects in development and if we are lucky they will join us and share. :thumb:

 

[daArry]

This might be a stupid question, but why do you have a JFP per channel? Isn't this a line-level summing mixer? Don't you just want one make-up gain stage at the end?

Indeed, I'm just using a JFP at the end, INA134 on inputs to act as a balanced rcv/buffer whatever...