Harrison Ford Filter Feeler

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dogfaceaudio said:
Does anyone have info on dimensions for drilling a front panel? Thanks.
Hello,
I only have the pitch between the pots which is 0,8 inches or 20,32mm.
No data for the e-switch position,I don´t use it,sorry.


Best regards,


Udo.
 
I thought I should share some results.
Have built them a couple of days ago.
Thanks to everybody here for this nice project,I did the first with some ic-sockets to experiment with caps and ended with the values Jens recommended here (thanks for that Jens,very useful especially on the ccw end of the hpf).
I went for THAT 1246 and 1646 for i/o,LT1058 as 074 replacement.
Did not use the bypass because with hpf to ccw and lpf to cw you already have a (pleasant sounding) little curve,so I will do a hard bypass later.
I did some rough measurements,no housing/shielding yet,running from a lab psu.
It shows the bumps nicely or better said why people like the sound.


Best regards,


Udo.


Here´s the curves for hpf (lpf is set fully cw):
 

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dmp said:
Nice work, Doug. 
So a  INA137 or THAT1246 on the input gives unity gain (instead of INA134, which is +6dB).

Those 134 chips are expensive - maybe the BOM on the first page could be updated?
Excactly,and +1 on updating the bom!
And thanks to Doug for pointing this out of course!


Best regards,


Udo.
 
dogfaceaudio said:
Anyone have a source for the 47K Rev. Log pots? Audiomaintenance is out.
Hello,I found this some minutes ago:


http://www.audiomaintenance.com/acatalog/om%2d01%2d028%5fextended%5finfo%2ehtml


Also I received a bunch of them yesterday,doesn't look like they're all gone.


Best regards,


Udo.
 
Hi, could I please buy some of these? I've asked a few times but nobody has answered me.

Thanks!

Marcocet said:
It looks like 12afael, Jens and I finally have a production version of this PCB ready and we're about to place an order for ourselves. Essentially it's a clone of the classic Harrison sweepable filters. The board runs on +/- 15v, has extremely few parts, and is tiny enough to fit a bunch in a rack case. It could also easily be built into a 500 series module. The hardest parts to source are the 47k Rev Log pots, which are available at Audio Maintenance (thanks Colin!).

I'm not trying to run a shop or anything, but if anybody would like a few boards I can figure out a price and add them in to our order. Please feel free to PM me or email me at strangeweathersound @t gmail.



EDIT:

Boards are sold out. Here's the BOM. I've attached an excel copy too for those who are that way inclined.

5 10k         R1, 2, 6, 7, 9
4 390         R3, 4, 5, 8

9 0.1u         C1, 2, 6, 7, 11, 12, 13, 15, 16
1 100p         C3
1 0.012u C4
1 0.047u C5
2 100u C8, 9 electrolytic
1 10u         C10 electrolytic

2 50k Dual Lin LOPASS, HIPASS Audiomaintenance.com
1 ESWITCH 2 pole switch Audiomaintenance.com

1 INA134P IC2
1 TL074P IC1
1 DRV134PA U$1

http://strangeweatherbrooklyn.com/sales/HarrisonFilterBOM.xls


schematic here
 
dandeurloo said:
skizotom, Just the input pads have the wrong silk screen on them.  If you look at the bottom of the PCB or use your DMM you can see the ground pads are tied together. 

Correct wiring is:
INPUT        OUTPUT
+  -    G        G  +    -
o  o  o        o  o  o



I hope that helps.


Hello,


just for info:


The output pins seem to be wrong too, + and - are swapped.
On a 1646 output positive is on pin 8(and 7),negative goes to pin 1(and 2).
Found it today having two filters on a stereo signal and bypassing one if them (hard bypass,insert on one channel temporarily switched off in ProTools).
I then looked at the ic pinouts and measured to the board connectors,found it.
So input is correct as stated in Dan's post above,the output isn't.

Best regards,


Udo.
 
I thought I'd share my 2-channel version of the filter:  8)
 

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I though I should share my first non-breadboard Harrison Ford Filter with you. It´s mounted on a 500 bracket with a frontpanel made by our member nrgrecording (frontpanels.de) and a 51x edge connector from (silent:arts). Like mentioned in this thread before I changed the filter caps because I wanted  the filters to be completely inaudible in their end positions.


 
I don’t see it in his white market thread but you could ask Volker aka [silent:arts] to find out for sure

CAPI has 51X and 500 series card edge adapters available in the US
 
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