Dr nEon
Well-known member
Hi everyone!
Newbie here with a calrec eq problem!
Firstly, a big thanks to Gyraf and all the regulars here...u guys are so inspiring!!
Ok , so I've built two channels of PQ1549 eq , from the rev4 pcb layout on jakob's site . The unit works first time :grin: ,has no noise or gain problems, and is nicely matched between the two channels.
However,on closer inspection.....
When I sweep tones , or check pink noise , I find that the frequency knobs are not corresponding exactly to what the original calrec scales suggest.
They are correct at the beginning and end of the pots travel ,but the 'curve' seems to differ..
For instance ;
hi mid 530 peaks at "530" mark
640 at 27deg above "640"mark
1K at 12 oclock position
2K at "3k6" mark
3k6 at about 10deg below "7k5"mark
7k5 at "7k5" mark
The lower side of the pot's range is expanded,while the upper side is compressed . All of the freq knobs are behaving exactly in this manner.
I started with omeg p20's , and then tried 16mm alpha , which also deviated from the panel dial markings.So now I have put in one of the lovely green eco range 16mm pots , ....but the curve of that is similar to the omeg p20. Back to square one! :roll:
Has anyone else experienced this ? ?
I am suspecting the pots , but could my problem actually be elsewhere in the circuit?
My psu is gyraf's mini-psu , using a 15 volt tx and 7815/7915.
Any help greatly appreciated!
nEon xx
Newbie here with a calrec eq problem!
Firstly, a big thanks to Gyraf and all the regulars here...u guys are so inspiring!!
Ok , so I've built two channels of PQ1549 eq , from the rev4 pcb layout on jakob's site . The unit works first time :grin: ,has no noise or gain problems, and is nicely matched between the two channels.
However,on closer inspection.....
When I sweep tones , or check pink noise , I find that the frequency knobs are not corresponding exactly to what the original calrec scales suggest.
They are correct at the beginning and end of the pots travel ,but the 'curve' seems to differ..
For instance ;
hi mid 530 peaks at "530" mark
640 at 27deg above "640"mark
1K at 12 oclock position
2K at "3k6" mark
3k6 at about 10deg below "7k5"mark
7k5 at "7k5" mark
The lower side of the pot's range is expanded,while the upper side is compressed . All of the freq knobs are behaving exactly in this manner.
I started with omeg p20's , and then tried 16mm alpha , which also deviated from the panel dial markings.So now I have put in one of the lovely green eco range 16mm pots , ....but the curve of that is similar to the omeg p20. Back to square one! :roll:
Has anyone else experienced this ? ?
I am suspecting the pots , but could my problem actually be elsewhere in the circuit?
My psu is gyraf's mini-psu , using a 15 volt tx and 7815/7915.
Any help greatly appreciated!
nEon xx