Preamplifier's universal input board building info/support

Help Support GroupDIY:

Igor

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Jul 17, 2006
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Israel
22uf 16v will be fine. 1uf input capacitor can be 63-100V, poly, Wima etc.

Yes, DI booster will work on +18 as well, with less output swing. Not sure every 24V relay will work on 18v btw...
Possible to check how many volts do you have on rectifier capacitors on power supply,
if + is more than +29V, it is possible to add +24V separate regulator, LM317 and some parts will do the job.
The board dimensions are 81x54mm.
 

Igor

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Jul 17, 2006
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Farnell seems doesn't have switches with nut, but these will fit:

http://il.farnell.com/multicomp/1ad1t2b4m7re/switch-pcb-dpdt-on-on/dp/1550173
http://il.farnell.com/c-k/e201md1av2be/switch-dpdt-r-a-pcb-on-on/dp/1437795
http://il.farnell.com/multicomp/1md1t2b4m7re/switch-pcb-dpdt-horiz/dp/9473319
 

noulou

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Sep 10, 2004
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Athens, Greece
I wanted Igor and anyone who wants to build this board know that the relay-driving transistor for the DI is marked upside down on the boards silkscreen.

So if you're planning on putting a pn2222 or 2n3904 NPN in there, put it upside down.

Thanks,
Nikos
 

radiance

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Jun 4, 2004
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the Netherlands
I'm going to use these for my api 312 build but I realize that the 312 has plenty of gain, so no need for boosting the line signal right?

I might just route the signal coming from the line input jack straight to the input transformer of the 312.

Or am I missing something?


EDIT: Duh...just realize it's a High Z input...

Never mind...
 

letterbeacon

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Jul 12, 2009
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London, UK
Does this DI add any colour to the signal at all?  I want to put it in front of a DIY 1290 but would like to keep the colouration of the Neve without adding to it.
 

dmp

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Oct 28, 2009
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Madison, WI
Does this DI add any colour to the signal at all?  I want to put it in front of a DIY 1290 but would like to keep the colouration of the Neve without adding to it.
How would one answer this question? I used this for my ez1290 project and it sounds great with a Precision Bass, which is all I've used it for, but i haven't done any 'colouration' tests...
 

mrcase

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Jan 19, 2009
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233
Location
vienna
Hi!

does anybody have a mouser / farnell link to which relay and which input jack fits the pcb?
and which is thte best substitute for the  BC214C??

cheers
 

okgb

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Oct 18, 2004
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Location
Winnipeg Mb Canada
Use a socket to try different transistors and use the old method of putting
a regular d.i. into the mic input to experiment with different combo's
[ it would be like using a countryman d.i.  - fet  - into the mic in ]
 

madreza

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Mar 8, 2005
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355
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Paris, France
Hi Igor,

I've gotta be missing something !!!!

I bought 10 DI's from you and have the same probleme on all 10 :
No Signal
tried feeding them with a 1Khz Sin , checked with Oscillo
I have a signal till the G pin of the J111 .... nothing further than that !
any idea ?
Thx
 

dmp

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Oct 28, 2009
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Madison, WI
No Signal
tried feeding them with a 1Khz Sin , checked with Oscillo
I have a signal till the G pin of the J111 .... nothing further than that !
any idea ?
Thx
I'd suggest you check that the bias on the G of the JFET is correct - should be about 12v. If not, you have a resistor wrong or a diode backwards.
If that is correct check that your pinout of the J111is correct for the pcb.
I've built these and they work - so you have a problem somewhere.
 

dmp

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Oct 28, 2009
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Madison, WI
Then pull the JFET and see if the voltage becomes correct. Problem may lie with your J111. Maybe the pinout is wrong or it is a bad part?
Look up the datasheet for the J111 you bought, verify that the pinout is correct for the PCB.
 

madreza

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Mar 8, 2005
Messages
355
Location
Paris, France
Thanks DMP for your help

In fact Igor Sent me a K170 instead of a J111
the pinout isn't the same and I didn't check that :D
now it works great !!!!
 
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