calrec PQ1549 help thread

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josh said:
I'm not sure if I have the correct component in the 1A Bridge position.
Pic attached. 
The text on it is DB102 V718
Different pinout http://www.datasheetcatalog.org/datasheets/70/193037_DS.pdf

Also, do you think I should heat sink the 78/7915's?
Would it matter if they are attached to the same sink?
Depends on your transformers secondary voltage. Differential between raw DC in and +/-15V DC out times current load is transfered to heat.
Use insulation kits when attaching (especially to same condusting) heatsink. 7815 has 0V reference voltage potential at heat fin that might cause a ground loop, 7915 has input voltage potential at heat fin that could get shorted out to reference voltage, maybe blowing your rectifying diodes.
 
On hand, I have a packet of WL005F's
http://www.datasheetarchive.com/dataframe.php?file=DSAP0031288.pdf&dir=Datasheets-111&part=WL005F#

I think I know why I picked the wrong one...
Can you please tell me how you know which terminal is NEG on the Gyraf schematic?  POS is marked, what does that arrow mean please?

The trans is an Amveco 62054-P2S02, spec sheet says 18V at the secondary.
http://www.amveco.com/Miniature_Low_Profile_Transformers.htm
 
josh said:
On hand, I have a packet of WL005F's
http://www.datasheetarchive.com/dataframe.php?file=DSAP0031288.pdf&dir=Datasheets-111&part=WL005F#

I think I know why I picked the wrong one...
Can you please tell me how you know which terminal is NEG on the Gyraf schematic?  POS is marked, what does that arrow mean please?
There is no schematic, only pcb trace side and component side shown at the minipsu.pdf. Arrow symbolizes bridge rectifier for this 4-pin device, containing 4 diodes in a BR arrangement. Negative side is opposite side of the positive side for the round shaped bridge rectifiers (or just follow the pcb trace to the center 7915 input pin).

The trans is an Amveco 62054-P2S02, spec sheet says 18V at the secondary.
http://www.amveco.com/Miniature_Low_Profile_Transformers.htm
Spec sheet doesn't say 18V at the secondary but dual 18VAC secondaries.
You connect both secondary windings in series, this series junction being the center tap connection that goes to '0V', located next to the AC solder lugs on pcb. With this now center tapped 36V AC transformer in front, each regulator will transfer the 10V differential between regulators raw DC in (about 25V) and 15V output voltage times current load (FI 10 dual opamps per channel, LED, ....) to heat, so better use heatsinks. Using 7818/7918 instead of 7815/7915 voltage regulators will give less wasted heat, but your opamps (whatever yours might be) have to be rated for this higher supply voltage, and the leftmost 22uF cap on calrec pcb has to be rated for at least this then +/-18V differential supply voltage, so better use a 50V or 63V rated part in this spot.
 
There is no schematic, only pcb trace side and component side shown at the minipsu.pdf. Arrow symbolizes bridge rectifier for this 4-pin device, containing 4 diodes in a BR arrangement. Negative side is opposite side of the positive side for the round shaped bridge rectifiers (or just follow the pcb trace to the center 7915 input pin).

sorry, when you know as little as I do, that's as schematic as it gets.
Yes, the (-) lead hits the center of the 7915 with the WL005F in place.  Thansks!

Spec sheet doesn't say 18V at the secondary but dual 18VAC secondaries.
You connect both secondary windings in series, this series junction being the center tap connection that goes to '0V', located next to the AC solder lugs on pcb. With this now center tapped 36V AC transformer in front, each regulator will transfer the 10V differential between regulators raw DC in (about 25V) and 15V output voltage times current load (FI 10 dual opamps per channel, LED, ....) to heat, so better use heatsinks. Using 7818/7918 instead of 7815/7915 voltage regulators will give less wasted heat, but your opamps (whatever yours might be) have to be rated for this higher supply voltage, and the leftmost 22uF cap on calrec pcb has to be rated for at least this then +/-18V differential supply voltage, so better use a 50V or 63V rated part in this spot.

I think I follow what you are saying here.
I have no idea where it came from anymore, someone on this forum, but I connected everything per the attached document.
plugged it in, and.... nothing.  1 channel works only in bypass, the other does not pass audio at all.

Anyone near Toledo Oh interested in helping me?
I'll buy you lunch!
 

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josh said:
..but I connected everything per the attached document.
Transformer primary windings black+violet and red+yellow joined for your local 115VAC mains ?
Your mains IEC socket might come with an internal fuseholder. Got the correct fuse fitted ?
Check if mains voltage arrives at your transformer with unit connected to your wall outlet and switched to power on by measuring voltage between the joined black+violet and red+yellow transformer wires with your multimeter set for reading AC voltage in the greater than expected 115V, so maybe 200V range if your meter is not auto sensing. IE black probe plugged into meters COM terminal, red probe plugged into meters V terminal. Black probe tip pointing at one junction, red probe tip pointing at the other junction. Order doesn't matter for AC voltage. When measuring, only use your probe tips, not your fingers! AC mains can be lethal. Got no multimeter, go buy one. They are cheap.
With confirmed mains voltage arriving at your transformer, check your psu with meter set for reading DC voltage in a greater than expected +/-15V, so maybe +/-20V range, black probe still plugged into meters COM terminal, probe tip at 0V reference voltage (keep it there), red probe still plugged into meters V terminal. With probe tip pointing at +15VDC psu output, meter should give you a steady readout of about (parts have tolerances) +15V. Probe tip pointing at the -15VDC output should give you a steady readout of about -15V.

plugged it in, and.... nothing.  1 channel works only in bypass, the other does not pass audio at all.
No supply voltage needed to operate in bypass. The bypass switch simply connects input with output. Just fix your solder connections for the not working channel, connecting to the correct XLR pins (XLR-in/out have mirrored pinout).

Anyone near Toledo Oh interested in helping me?
Naaa, you've already come so far. You'll take the final step yourself. This is DIY. ;)
 
Harpo,
I do have a multimeter :) and thank you for detailing out where to check, and more importantly.. HOW.
Thanks for taking the time to do that.  I will do what you said and report back my findings.

My SSL has a 2 Amp fuse, my G9 has a 5 Amp fuse, the Calrec I put a 3 Amp in there because I had one laying around, but I must confess that I have no idea what they are supposed to be.  :-[  what tells you this?
 
josh said:
My SSL has a 2 Amp fuse, my G9 has a 5 Amp fuse, the Calrec I put a 3 Amp in there because I had one laying around, but I must confess that I have no idea what they are supposed to be.  :-[  what tells you this?
Scary.
I'd pick a 250mA [15VA transformer/115V AC mains*1.6 = 0.209A] slow blow fuse for your Amveco62054 with slow blow '/t' fusing characteristic.
 
gyraf said:
if you have buzz noise, that will be hum.

This is common when it's not mounted in a metal enclosure.

For testing, throw everything inside a grounded (connected to 0V) metal box and recheck.

If there is still hum, it must come from your power supply (assuming that it's not in your input signal). Then clean up powersupply.

Jakob E.

I understand that Jakob,thanks,I put it in something like a Metal box(a big metal sheet because I have not the box yet) and connecting ground to it and the noise disappear...after my university exams I will start making box and I will put the picture of complete unit here.thank you so much for your helps and your patience in answering our questions.you are a really,really nice guy. :)
 
You could calculate the needed resiasors for specific frequencies for the state-variable filters - or you could use two trimmers, set them to wanted frequency, dismount them and measure them for each wanted frequency.

Or you could just use the logarithmic step calculation "backwards"

But I'm not sure that stepping the frequency is such a good idea - often it's fine adjustments that is needed in eq's like this. 2x100KC pots are not impossible to find at all nowadays.

Jakob E.
 
Nescafe said:
I have observe the filter and need help to make sure, is anybody know if the filter component to calculate are like in the attached pics (only the mid section, but it looks like the same except the value for other band)?
The 22nF across opamp 8B output/inverting input (right side next to your red circled area) is part of the frequency setting network as well. Filters center frequency is 1/(2*PI()*SQRT((1000+1/(1/100000+1/15000))*22E-9*(1000+1/(1/100000+1/15000))*22E-9)), giving range 515Hz up to 7234Hz (when substituting the 1/(1/100000+1/15000) term with zero for the shorted out pots full CW setting) for this stage with perfect parts.
 
Nescafe said:
- low 47.7 to 446.6 but if I put the pot value 0.0001 (near short) the Freq 669.9
center peaking response from 1/(2*PI()*SQRT((1500+1/(1/100000+1/27000))*68E-9*(1500+1/(1/100000+1/27000))*(680+150)E-9))=29.43Hz
up to 1/(2*PI()*SQRT((1500+0)*68E-9*(1500+0)*(680+150)E-9))=446.62Hz.
The Calrec original schematic says 30Hz to 470Hz.

- high 1666.6 to 15603.4 and if I put the pot value 0.0001 (near short) the freq calculation 23405.1
center peaking response from 1/(2*PI()*SQRT((1500+1/(1/100000+1/27000))*6.8E-9*(1500+1/(1/100000+1/27000))*6.8E-9))=1028.35Hz
up to 1/(2*PI()*SQRT((1500+0)*6.8E-9*(1500+0)*6.8E-9))=15603.42Hz.
The Calrec original schematic says 1kHz to 16kHz.

I assume the equation is different for the low and high band, would You like to inform me how to calculate the high and low band freq?
Peaking response is the same, just substitute the different values for caps and resistors. Shelfing response is different.
 
Nescafe said:
1. what is the value of q when low and high of this eq (bell position)? Is there any formula to calculate the q and also which component in the schematic are for q control?

I haven't messed with the Q ever - the choices from Calrec seems very good indeed. The Q is set by the positive feedback over the two integrator stages - look up state-variable filters for calculations.

Nescafe said:
2. if use 5532, can I make the PSU higher, let says 20V? Do this will benefit to get higher headroom?

I don't think you'll gain anything real from this - but you could always try...

Nescafe said:
3. any idea what kind of output transformer is suitable for this circuit?  ;D ;D ;D

Driven from these opamps, I'd say just about anything around 600:600 Ohms or so - maybe LL5402?

Jakob E.
 
Nescafe said:
is that OK to use silver mica cap in the place of all tantalum and ceramic?
Sure ::), but you'd need a LOT of bucks and a GIANT box to fit them for a sub par result. (largest stocked value about 1nF. You'll have to fit 33000 of these caps in parallel to substitute a single 33uF cap, times 12 for a stereo build giving 396000 caps needed to substitute the 12 tantalum caps).
I'd use c0g/np0 for the cer.caps and low ESR electrolytics for the tants. YMMV.
 
Hello Everyone ,
                          After a couple of months of hitting a brick wall on a dual 1176 Rev.D - I decided to clean my work bench and take a breather... well I couldn't stay away from DIY too long, so I went back to this dual Calrec 1549.

  I have to say that this, by far was the most difficult project to physically assemble ( for me anyway ), as I had the pot holes counter bored to recess the pot nuts.  I used the switches and pots from AML.  I actually needed 22k pots for another project and the only ones AML had with 3/8 bushing and 1/4 shaft has center detentes which I didnt need , so I disassembled the pots and swapped the wafers ( voids warranty )  so I have 10k Lin with center detentes for the +/-
  I used the LM833 as suggested by Gyraf , I have W492's and S800's with NE5532's , so I wanted to try the LM833's. I made the front panel graphic in Illustrator and Chae at Prodigy engineering laser engraved it. The knob grapgics are for 3/4" knobs and the the push buttons I got very cheaply from ebay and fit the ALPS push button switches - black anodized aluminum and are 0.310" or 7.88mm in diameter so they are smaller in Diameter than the ALPS button caps which gave a little more room for the knob graphics.

    I have posted the PDF of the final panel graphic , if you want the Illustrator file I will email it to you , but a word of WARNING -  the push button holes are as exact as I can get them , the switches have a little wiggle room and I had to de-solder and then re-solder them after mounting PCBs to the panel to get them centered - very much a PITA .

  It sounds great and I'm sure will be very useful,
                                                                              Thank you to Jakob and Gyraf and all who post and contribute,
                                                                                                                                                                                  Chip

here is a link to more pix -  https://goo.gl/photos/buXRjzi2oV9gWfvQ6
 

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Thanks Nescafe, she sounds great and I have heard these described as  " surgical " and now know why  ;D

  Jacob, that means so much coming from the man who made all this possible. I have now completed all the DIY projects that you have given this comunity ( at least all the projects on your DIY page ). Thank you for years of enjoyment ( and a little fustration  ;D  )  , and gaining of knowladge ( tons more to learn ) , and great sounding DIY equipment.
 

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