calrec PQ1549 help thread

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Hey Mylithra, that looks great!

I'm finishing off something very similar right now. Are those Omeg ECO pots you've used? If so, could you possibly tell me the Canford order numbers for the switches? The reason being that the Alps switches I have don't sit central in the holes on Purusha's case.

Cheers!

Matthew
 
Heh.. Thanks..
Yes.. Those are Omeg Eco Pots, but the switches are the ALPs SPUN switches. And Yeah.. they dont line up 100% when the switches are soldered flush to the board. I ended up de-soldering them (Hakko 808 is a godsend), lining them up, then soldering them back in. The only thing I ordered from Canford for this was the push button caps. Those are the round ones made by Re'an.


MatthewF said:
Hey Mylithra, that looks great!

I'm finishing off something very similar right now. Are those Omeg ECO pots you've used? If so, could you possibly tell me the Canford order numbers for the switches? The reason being that the Alps switches I have don't sit central in the holes on Purusha's case.

Cheers!

Matthew
 
Hi there,
I've been working on my non-working board problem and I've discovered a strange behavior that might help finding the solution:

On the non-working board, when I power it up, I get signal for about 1 second, and then nothing. So I've tried to play around with the EQ controls and repower it: it's definitly wet well processed signal that show up for 1 second at each reboot ! So I guess the EQ works but for a short time and then nothing...

If it was a short-circuit or a bad solder issue, I would have no signal at all, even at the boot. Am I right ?

It can not be a PSU problem as the first board works perfectly.

Thanks for your time.
 
I finally got my CALREC eq to work (thanks to some hands-on help from a good friend) and I also noticed a jump in gain with all the band's level controls flat. as I quite like to have a gain control on an eq to compare with the untreated signal, I was thinking of inserting a dual gang pot instead of just changing the 10k resistors to 22k. so I tried the following mod:
calreclevelctrl.gif

This allows me to have resistances from 10k-32k and to make up for moderate cuts and/or boosts. Is this kosher or am I comitting untold crimes on input impedances etc? if - due to pot tolerances - I have a different resistance on the plus and minus rails, what would the effect be?

ETA: I ended up using dual rev log 100k pots (instead of 22k) for the gain (same as the ones spec'd for frequency) to get the required range.
 
Is this kosher or am I comitting untold crimes

You mess a bit with the input CMRR because of the inherent tracking error of the pot, but if you don't need to feed it from long lines through noisy environments, I'd say it'll be fine...

You could make the series input resistors 4K7 in stead of 10K to get a larger gain range.

Let us know if it turns out right..

Jakob E.
 
...or use a 2deck MBB rotary switch. to keep CMRR happy, select the values of the resistors to match as close as possible...
 
SIXTYNINER said:
sorry for question

is this a full parametric eq with variable "bell" /q
or a semiparametric eq?

thanks in advance
???

somewhere in between.... :p
the q is switchable between two alternative values for each of the four bands.
the narrower setting (higher q) is very 'notch-like' and IMO more suitable for cutting frequencies.
additionally the top and bottom bands can be switched to shelf, in which case the corresponding q button is inactive.

it's also a great sounding box  :)
 
briomusic thanks for post

by a first look this eq seem similar to standard eq ,
as default on soundcraft ts12-600-1600-2400....,DDA QMR,DMR.... ,  mackie 8 bus, allen & heat,soundtracs ,d & r......
"mid level" mixing consoles.....
i think if a "discrete opamp" as in api can replace the 5532 ic of this project
this eq can be very interesting....

Please: MR. jacob do you think it can be a good idea (and possible)try to developing this
good project with discrete opamp?

someone have just trYed to design a discrete opamp replacement for 5532?
thanks in advance
6T9R
 
Hi! I've finished my calrec eq now and done some quick testing and everything seems to work. The only thing left now is the knobs!! Do anyone have any suggestions on some knobs for this baby?? It would be nice with some knobs that gives it an expensive look and feeling :). Have not found the buttons for the alps switches, where can i buy these?

At last i have a question about the power transformer. I've used a torroid from hairball audio, and mnats power supply board. Everything works fine and i get the right voltages and everything(+/- 18V DC) but when i measure from the center tap to ground i get 25v AC. I feel like i miss some basic knowledge about transformers?!?! Since the PCB "0" goes to the output will this bring any trouble in the next unit in the chain whit some current that might destroy something in other units. Im a little lost here and i think its important to fully understand theese things.

Cheers!
 
Hi All,
I have i question about the input connector of the calrec pq 1549 ,
I have see on the board labeled balanced input are use a two pin connector why ??
Can i take the zero volt from the output connector ???
Please let me know
Thank you all
Fabio
 
Hi All,
I have an electronic problem wit my Calrec eq on the hi frequency section
The problem is :
when i gain the max db on the pots hi frequency with the switch shelvin not pushing and the switch Q pushed the sound seems to be autooscillation and when you push the shelvin switch the problem disappear !!
i have no idea of  where is the problem but i have change all the tantalium and all the electrolitycs and all the ic's NE5532
I have ceck also all the soldering point and it was all ok no short
Please let me know if you have any idea
 
No test guide with voltages available - wouldn't make sense.

Check and recheck resistor values.

For input ground, re-use output ground.

I don't think much will be gained by using a discrete opamp here - better reserve that for the Sontec-type circuits.

Jakob E.
 
After some audio test in my studio the only problem on my calrec is :
only on the high frequency section when i gain max db at the highest frequency possible if i push the switcj Q the autooscillation appear and if turn down the frequency pot at 8k the autooscillation disappear !!!
Any idea ?????
let me know
thank you all !!
Fabio
 
So I finished stuffing the boards and built the PSU. My fear now is regarding the capacitor voltage ratings and would really appreciate some advice there. The PSU is the recommended 18v and I assembled the eq using the recommend 16v caps on the calrec. I've also read about the cap that would see 36V.

My questions are:
- Do I really need to replace every cap with a higher rating?
- or are there just a few caps that I need to replace (such as the one seeing the 36V)?
- or do I need to build a 15v power supply (even though a cap sitting across + and - would still see 30v)?

Any help would really be greatly appreciated as I didn't expect this problem with the BOM and silkscreening being incorrect.

Marc
 
Option #1
Replace all 6 of the 22 uf caps to a voltage rating of 63V
Option #2 Replace the one near the shelve switch and power everything with 15V or less.

Good thing you reminded me, I need to replace some caps myself because of this on mine that I'm going to be finishing here real soon. I'll just order some 63V caps all around and call it good.
 
Thanks Kazper!

Glad my message was of some use too you too. Really good to have confirmation that it's only those 6 caps that need replacing and none of the other 16v caps. I was worried there were going to be more. Now I should have the build finally completed this week!

Thanks again and hope the build goes well for you,

Marc
 
For the dual 100k reverse log pots can you use dual 100k linear pots. What effect would this have?

Michael
 

Latest posts

Back
Top