Harrison Ford Filter Feeler

[G-Sun]

I believe "Taper: Audio" is rev.log (but I'm not the expert)
Else AML is 47k rev.log aren't they (at least mine are), so I'd go for 50k. Looking good to me.

Somebody else could chime in on the practical difference linear vs. rev.log

 

[straypacket]

Well,  I took the plunge into the pond, and ordered my potentiometers and pushbuttons from AML   I'd rather pay a bit extra and ensure compatibility - as patience and component removal are not my strong suites.

I have an Avel 30vac 18+18 toroidal xformer coming from eBay, and will be ordering the JLM Powerstation kit.

PCBs and case coming from Dan, too.

So, it this all works out - I will have 2 channels of GSSL, and 2 channels of Harrison EQ.  Too bad it's going to be fed by a JoeMeek TwinQ (although I shouldn't slag the preamps - they're not horrid or anything).

Has anyone mounted a toroid and PS inside Dan's cases?

 

[signalflow]

I believe "Taper: Audio" is rev.log (but I'm not the expert)
Else AML is 47k rev.log aren't they (at least mine are), so I'd go for 50k. Looking good to me.

Somebody else could chime in on the practical difference linear vs. rev.log

Audio Taper refers to a standard Log Potentiometer. 
What you are after is a Rev Log or a Rev Audio Taper pot for this.

And before you ask, wiring the pot backwards will not produce the results you're after.

Generally speaking designations for pot taper are:
A=Log
B=Linear
C=Rev. Log

So a 10KA would be a 10K Log and so on.

AML is the only store I've found that has anything remotely close without having to put together a group buy for 50KC Dual Pots.  Except for the SSL online store, but they are more expensive than AML plus they wont fit the boards.

-Casey

 

[dandeurloo]

A number of guys have asked about PSU's for this project.  I ended up using one I purchased from ebay.  I had to put shorter filter caps in and cut down the heat sinks but it has worked great and was really pretty cheap.  I got it from this seller.  I have actually used these in a number of projects.  So it may be worth it to grab a few for future projects.


http://myworld.ebay.com/electronics-salon?_trksid=p2047675.l2559

Here is a link for the PSU I used.
http://www.ebay.com/itm/Power-Supply-Board-Kit-PCB-Based-on-LM317-LM337-IC-/260484989112?pt=US_Amplifier_Parts_Components&hash=item3ca61d80b8

I then used a transformer from Antek.
http://www.antekinc.com/gview.php?d[]=0

I hope that helps.

 

[Harpo]

Generally speaking designations for pot taper are:
A=Log
B=Linear
C=Rev. Log
So a 10KA would be a 10K Log and so on.

...for pots from US based manufacturer.
European taper marking might as well be A=linear; C=log; F=rev.log
Asian taper marking might as well be A=log; B=linear
Vishay also used taper marking A=linear; L=log; F=rev.log
Better read the datasheet or measure the pot at mid travel if an 'A' taper pot marking is an indicator for a lin or log taper.

 

[G-Sun]

Generally speaking designations for pot taper are:
A=Log
B=Linear
C=Rev. Log
So a 10KA would be a 10K Log and so on.

...for pots from US based manufacturer.
European taper marking might as well be A=linear; C=log; F=rev.log
Asian taper marking might as well be A=log; B=linear
Vishay also used taper marking A=linear; L=log; F=rev.log
Better read the datasheet or measure the pot at mid travel if an 'A' taper pot marking is an indicator for a lin or log taper.

LOL
I'll just copy that into my notebook. Thanks!

 

[minor_glitch]

Quick photo of work in progress.  Everything seems to fit nicely.  Now on to the psu, wiring, etc...

 

[straypacket]

A number of guys have asked about PSU's for this project.  I ended up using one I purchased from ebay.  I had to put shorter filter caps in and cut down the heat sinks but it has worked great and was really pretty cheap.  I got it from this seller.  I have actually used these in a number of projects.  So it may be worth it to grab a few for future projects.
...

Thanks Dan!  I wish I knew about Antek before.  I've ordered a transformer and power supply kit from the sources you referenced.

Out of curiosity, how do you wire from the PSU to the eight PCBs - series, parallel, other?  Does it matter?

 

[butlerscheme]

That's something i'd also like to know.  Do you wire the PSU to board 1 of 8 and then daisy chain them on??

 

[dandeurloo]

Yes, daisy chain them. That is how I did it anyway. 

 

[G-Sun]

That's something i'd also like to know.  Do you wire the PSU to board 1 of 8 and then daisy chain them on??

This is something I don't understand.
Wouldn't that mean putting the circuits in series, thus giving each board 1/8 of required voltage?

 

[tmuikku]

That's something i'd also like to know.  Do you wire the PSU to board 1 of 8 and then daisy chain them on??

This is something I don't understand.
Wouldn't that mean putting the circuits in series, thus giving each board 1/8 of required voltage?

Daisy chaining makes them parallel, all get same voltage. Just the way you've got your TV, VCR and DVD player on an extensioncord

 

[straypacket]

My case from Dan arrived yesterday!!  Knobs are on their way, from another forum member.

2 boards completed.  Only 6 more to go, then the daunting task of wiring the db25 connectors...  I'm tempted to just see if I can squeeze 16 TRS jacks in the space between the star ground hole, and the first db25

What did others do for sourcing their knobs?

 

[dmp]

What is the part # for the power switch for Dan's case? Anyone know offhand?

 

[dandeurloo]

I'm 90% sure its Mouser Part #: 611-D102J12S217DQA.

 

[dmp]

Anyone thought about adding a mix out - i.e. summing the 8 channels to a single XLR out? Might need some gain makeup I suppose.

 

[emrr]

What are the dimensions of these boards?  I don't see that info anywhere.  Thanks.

 

[straypacket]

Hi emrr -

I dug out my spare boards and gave one a measure -  they are approx. 91mm x 41mm.


Hi Group -
So, no one has sourced knobs for these yet ?????

 

[dandeurloo]

Hi Group -
So, no one has sourced knobs for these yet ?????

Straypacket post #206 has part # for knobs form Silco.  You have to order them direct but they work great.  I ordered knobs from them as well for my Sontec.

 

[emrr]

Are these boards turning out 25-2K75Hz HPF and 160-20kHz LPF like the current Harrison/Great River product?  I really can't make out the legend on the case in any pictures, and don't find that info anywhere in the thread, only G-Sun's comment that his appear to show:

65-4k Hz, and the highcut goes from 14k-125Hz.

Here's an alt 20Hz-200Hz version of the HPF, possibly of interest to some off-roaders.  This appears the most common circuit found in a google search.  Looks like this variation with lower filter gain lacks the ripple boost above the cut-off frequency.