Preamplifier's universal input board building info/support

« **Reply #20 on:** August 21, 2009, 10:53:50 AM »

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.

« **Reply #21 on:** October 12, 2009, 11:58:53 AM »

anyone have a type-number of the switches to use? preferably from Farnell or RS..
thanks

« **Reply #22 on:** October 12, 2009, 01:37:53 PM »

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

« **Reply #23 on:** November 12, 2009, 08:17:13 AM »

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

« **Reply #24 on:** November 12, 2009, 08:30:08 AM »

OOPS... Anyway, refer to CBE printed on PCB, it is right.

« **Reply #25 on:** January 17, 2011, 07:03:09 AM »

Hi Igor,

I'd like to order four of these fantastic boards, with two of the 24 / 48 v PSU Boards please,
Kindest regards,
Steve

« **Reply #26 on:** April 06, 2011, 10:34:05 AM »

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...

« **Reply #27 on:** April 06, 2011, 01:06:16 PM »

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.

« **Reply #28 on:** April 06, 2011, 01:24:09 PM »

Quote

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...

« **Reply #29 on:** August 23, 2011, 09:32:39 AM »

Igor.
Can i use both fets here?
schematics says J109 and pcb says J111??
Thanks.

« **Reply #30 on:** October 07, 2011, 04:49:09 AM »

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

« **Reply #31 on:** October 07, 2011, 08:31:28 AM »

Igor is too bussy !
I asked a question a few weeks ago!

« **Reply #32 on:** October 07, 2011, 09:28:41 AM »

Maybe I`ll try via his shop....

« **Reply #33 on:** October 07, 2011, 12:10:46 PM »

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 ]

« **Reply #34 on:** January 30, 2012, 07:06:33 AM »

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

« **Reply #35 on:** January 30, 2012, 09:58:21 AM »

Quote

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.

« **Reply #36 on:** January 30, 2012, 04:03:26 PM »

thanks dmp
in fact I get 4.8V !
gonna check the resistors value and the diodes

« **Reply #37 on:** January 30, 2012, 06:52:08 PM »

Diodes are fine, resistors have the right values !!!!!

« **Reply #38 on:** January 31, 2012, 10:02:46 AM »

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.

« **Reply #39 on:** February 07, 2012, 08:15:08 AM »

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

now it works great !!!!

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