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calrec PQ1549 help thread
- Thread starter JayDee
- Start date
Help Support GroupDIY Audio Forum:
rbaker
Well-known member
I have a stereo unit and it has the extra gain problem (Didn't see the post about altering the resistors) I'll do that when I open it up again.
Also I'm having a problem with the high frequencies. On one channel, it absolutely does nothing..
On the the left, it does nothing unless the shelf is engaged and then its basically just a level adjustment (not frequency dependant) if I boost, it boosts the whole signal. If I cut, it cuts the whole signal.
I remember being overly careful about solder bridges, but I'll check again. Any ideas of where to look or what might cause this to happen?
Also I'm having a problem with the high frequencies. On one channel, it absolutely does nothing..
On the the left, it does nothing unless the shelf is engaged and then its basically just a level adjustment (not frequency dependant) if I boost, it boosts the whole signal. If I cut, it cuts the whole signal.
I remember being overly careful about solder bridges, but I'll check again. Any ideas of where to look or what might cause this to happen?
..it could be anywhere in the hi-freq filter or -add/boost section (see schematic)
rbaker
Well-known member
so I finally had a chance to open it up...
On the channel where the high freq was acting like an output fader, it turns out I missed two jumpers.
Now that channel is working great.
On the other channel where the high frequency just doesn't work whatsoever, I looked for solder problems and there wasn't anything I could find--(I cleaned on semi-suspicious solder joint but it didn't help)
I noticed when the unit is not bypassed and I press the high shelf switch it makes a pop sound in the audio (the functioning channel doesn't do that)
Also I changed the resistors (22k) you mentioned for unity gain, and it definitely helped but I still have about 3.5db of extra gain. Is there any problem with increasing this resistance further?
On the channel where the high freq was acting like an output fader, it turns out I missed two jumpers.
Now that channel is working great.
On the other channel where the high frequency just doesn't work whatsoever, I looked for solder problems and there wasn't anything I could find--(I cleaned on semi-suspicious solder joint but it didn't help)
I noticed when the unit is not bypassed and I press the high shelf switch it makes a pop sound in the audio (the functioning channel doesn't do that)
Also I changed the resistors (22k) you mentioned for unity gain, and it definitely helped but I still have about 3.5db of extra gain. Is there any problem with increasing this resistance further?
josh
Well-known member
Couple more questions if everyone doesnt mind. If I might be a pain, the answers to the questions are hardly as important as to how you know the answer please? :thumb:
1. each "high" board has a balanced input and balanced output (according to the Calrec.pdf) and a third section marked (OUT) on the boards. What is this?
2. the "low" board has no markings for the input section, and the place I thought was the input is marked on the Calrec.pdf as the -+0 18V PSU. Does that mean the input is part of the 6 pin connector on the "low" board but not the high? Why?
3. the mini-psu I built specifys +-15V output, but the Calrec.pdf is labling the boards with +-18V? Does that matter?
I read every thread and every link in the Meta last night. Apparantly I am the only one thrown by this, but it really doesn't make any sense.
1. each "high" board has a balanced input and balanced output (according to the Calrec.pdf) and a third section marked (OUT) on the boards. What is this?
2. the "low" board has no markings for the input section, and the place I thought was the input is marked on the Calrec.pdf as the -+0 18V PSU. Does that mean the input is part of the 6 pin connector on the "low" board but not the high? Why?
3. the mini-psu I built specifys +-15V output, but the Calrec.pdf is labling the boards with +-18V? Does that matter?
I read every thread and every link in the Meta last night. Apparantly I am the only one thrown by this, but it really doesn't make any sense.
1."out" is where you place jumpers connecting two boards, those tracks actually carry the "output" signal...
2.Calrec.pdf markings are O.K. just follow them...
3.+/-15v is cool, you'll lose some headroom due to the lower voltage rails,
i think around 1dB ...
1.pink: PSU
2.blue: jumpers that connect two boards together
3.green: audio input and output (to XLRs)
hope this helps...
2.Calrec.pdf markings are O.K. just follow them...
3.+/-15v is cool, you'll lose some headroom due to the lower voltage rails,
i think around 1dB ...
1.pink: PSU
2.blue: jumpers that connect two boards together
3.green: audio input and output (to XLRs)
hope this helps...
josh
Well-known member
I love you man.
I have an 18V toroid, but I bought it for my pico comp. Do you suppose I should just get another one and use the heavier supply? 1db isnt much then again.....
I have an 18V toroid, but I bought it for my pico comp. Do you suppose I should just get another one and use the heavier supply? 1db isnt much then again.....
Josh
Regulators will have plenty to regulate from, if you use 18V dual secondary toroid. From memory 1549 needs around 150mA per a chn.
Using that toroid will give you +/-18 VDC after a decent PSU (like jlm ac/dc or power station) just check its power rating...
Regulators will have plenty to regulate from, if you use 18V dual secondary toroid. From memory 1549 needs around 150mA per a chn.
Using that toroid will give you +/-18 VDC after a decent PSU (like jlm ac/dc or power station) just check its power rating...
josh
Well-known member
I built the mini-psu that gyraf posted. It's p2p on verobaord so I hope it works.
I think that you'll be regulating from ~25V down to 15V if you made the
PSU as on the Gyraf's schematic. 78/79-15 will need to drop ~10V and they might need heatsinks. You could change regulators for 18V version
of them and have less heat dissipation... Triple check as I don't use
78xx series and I’m not very familiar with their "real world" performance...
PSU as on the Gyraf's schematic. 78/79-15 will need to drop ~10V and they might need heatsinks. You could change regulators for 18V version
of them and have less heat dissipation... Triple check as I don't use
78xx series and I’m not very familiar with their "real world" performance...
guitarmaker
Well-known member
I used the mini PSU and regulated to 18vdc no problem.
Steve
Steve
josh
Well-known member
I looked through the help thread but didn't see any explanation as to what this is?
Can I really use it as an insert point with only 2 solder points?
Am I to jumper those points for normal opertaion then?
What about the led. Can I connect a regular led until I find one of those multicolor jobbies? I'm not seeing which is + and which is - from the schemo though. Anyone know?
I am 1 hour away from being done guys!
I would take a photo but some asshole stole our camera out of my wifes purse when she was at work the other day. So that's a no-go.
Regarding the psu, I think I'll put some sinks on there, no biggie.
Can I really use it as an insert point with only 2 solder points?
Am I to jumper those points for normal opertaion then?
What about the led. Can I connect a regular led until I find one of those multicolor jobbies? I'm not seeing which is + and which is - from the schemo though. Anyone know?
I am 1 hour away from being done guys!
I would take a photo but some asshole stole our camera out of my wifes purse when she was at work the other day. So that's a no-go.
Regarding the psu, I think I'll put some sinks on there, no biggie.
Hi Josh
i don`t understand your first question.
as for the leds:
the led has 3 legs.the midlle leg goes to the midlle hole in the board.the other two legs ,one in one hole,and the other to the other hole.
best regards
pedro
i don`t understand your first question.
as for the leds:
the led has 3 legs.the midlle leg goes to the midlle hole in the board.the other two legs ,one in one hole,and the other to the other hole.
best regards
pedro
josh
Well-known member
Hardy Har Har
I'm just going to assume you are drunk and are just checking to see that you can still type? :sam: :thumb:
I'm just going to assume you are drunk and are just checking to see that you can still type? :sam: :thumb:
josh
Well-known member
Ok everyone.
I am all done. It's not working. Now I am going to admit what I don't know so please be nice about it. I don't know how to check voltages. What points and what they are supposed to be.
Can someone help me with this please? I've never had to, so far my GSSL and G9 both worked upon first power up so I never had to try and look.
I really assume that my psu is mucked up because I built it on veroboard p2p and all. It's a bit of a mess under there. So, what voltages should I have coming out of the psu? I did go ahead and use the 2x18V power toroid I had because I didn't want to order anymore parts right now.
As I mentioned above, I dont know what the "link or insert point" is supped to be, I jumpered those 2 points together since there was a line connecting them like all jumper points. Is that correct?
And SYN!!! that diagram was exactly perfect man, thanks alot for that. It was exactly what I needed to know bro. :thumb:
I am all done. It's not working. Now I am going to admit what I don't know so please be nice about it. I don't know how to check voltages. What points and what they are supposed to be.
Can someone help me with this please? I've never had to, so far my GSSL and G9 both worked upon first power up so I never had to try and look.
I really assume that my psu is mucked up because I built it on veroboard p2p and all. It's a bit of a mess under there. So, what voltages should I have coming out of the psu? I did go ahead and use the 2x18V power toroid I had because I didn't want to order anymore parts right now.
As I mentioned above, I dont know what the "link or insert point" is supped to be, I jumpered those 2 points together since there was a line connecting them like all jumper points. Is that correct?
And SYN!!! that diagram was exactly perfect man, thanks alot for that. It was exactly what I needed to know bro. :thumb:
Harpo
Well-known member
[quote author="josh"]I really assume that my psu is mucked up because I built it on veroboard p2p and all. It's a bit of a mess under there. So, what voltages should I have coming out of the psu? I did go ahead and use the +-15V power toroid I had because I didn't want to order anymore parts right now.[/quote]
what is your transformers secondary? (+-15V power toroid doesn't make much sense, as a transformer is AC not DC). You'll need a 2x15V AC secondary or a 30VAC center tapped one (2x12,5VAC is the lower limit, 2x24,5V is the upper limit, producing lots of heat) to get a simple (without voltage doublers, ...) +/-15V DC supply, the calrec is asking for.
Assuming yours is a 30V center tapped transformer, your meter will read ~30V AC across the transformers outer secondaries. With the transformers center tap connected to 0 (or the connected inner windings of your dual secondary connected to 0), the 2 outer secondary wires connect to the AC leads of your bridge rectifier. Across your +/- leads of your rectifier you will measure about 40V DC or ~20V DC between +/0 and 0/- before the voltage regulators. Take care, that 78xx and 79xx have a different pinout and don't mount these regulators unisolated to the same heatsink as the metal sink of these have different potential. These regulators will need a load connected to their output to work properly. This can be eighter a resistor (maybe 1k5 resistor with led in series between +15V/0 and 0/-15V, indicating a current draw of 10mA for each rail) or your calrec or whatever circuit.
what is your transformers secondary? (+-15V power toroid doesn't make much sense, as a transformer is AC not DC). You'll need a 2x15V AC secondary or a 30VAC center tapped one (2x12,5VAC is the lower limit, 2x24,5V is the upper limit, producing lots of heat) to get a simple (without voltage doublers, ...) +/-15V DC supply, the calrec is asking for.
Assuming yours is a 30V center tapped transformer, your meter will read ~30V AC across the transformers outer secondaries. With the transformers center tap connected to 0 (or the connected inner windings of your dual secondary connected to 0), the 2 outer secondary wires connect to the AC leads of your bridge rectifier. Across your +/- leads of your rectifier you will measure about 40V DC or ~20V DC between +/0 and 0/- before the voltage regulators. Take care, that 78xx and 79xx have a different pinout and don't mount these regulators unisolated to the same heatsink as the metal sink of these have different potential. These regulators will need a load connected to their output to work properly. This can be eighter a resistor (maybe 1k5 resistor with led in series between +15V/0 and 0/-15V, indicating a current draw of 10mA for each rail) or your calrec or whatever circuit.
josh
Well-known member
Sorry Harpo, I'll stop casually throwing aroud terms I dont fully understand. The voltages coming out of the PSU board are listed as +/-XX, not the toroid.
I'm using the Amveco 62054-P2S02 http://www.amveco.com/pdf/Amveco_Catalog.pdf#page=25
My mistake, it's a 2x18 power toroid.
I haven't heat sunk the regulators yet. I was going to have one of the guys at work make some custom sinks once I got everything working good. I wont connect them. I think I follow what you are saying about loading them, sort of....
http://www.gyraf.dk/gy_pd/calreq/minipsu.pdf
do I need to make a change to this circuit? I built it exactly as it shows and connected Red/Brown to 0, and Blue to AC and the Green to the other AC (does order mattter there?). Coming out the other side I have Red/Yellow going to N, and Black/Violet going to the unmarked pin on the IEC. Then I have the IEC gound running over to the Input XLR mounting bolt, and both Input XLR pin #1 are going to that bolt as well. That's my star ground.
All this is correct, isn't it?
I would just post a picture, but someone stole our camera when my wife accidentally took it to her work. We were supposed to go out and pick up another one tonight, but she's mad at me and we're not going anywhere.
I'm using the Amveco 62054-P2S02 http://www.amveco.com/pdf/Amveco_Catalog.pdf#page=25
My mistake, it's a 2x18 power toroid.
I haven't heat sunk the regulators yet. I was going to have one of the guys at work make some custom sinks once I got everything working good. I wont connect them. I think I follow what you are saying about loading them, sort of....
http://www.gyraf.dk/gy_pd/calreq/minipsu.pdf
do I need to make a change to this circuit? I built it exactly as it shows and connected Red/Brown to 0, and Blue to AC and the Green to the other AC (does order mattter there?). Coming out the other side I have Red/Yellow going to N, and Black/Violet going to the unmarked pin on the IEC. Then I have the IEC gound running over to the Input XLR mounting bolt, and both Input XLR pin #1 are going to that bolt as well. That's my star ground.
All this is correct, isn't it?
I would just post a picture, but someone stole our camera when my wife accidentally took it to her work. We were supposed to go out and pick up another one tonight, but she's mad at me and we're not going anywhere.
Harpo
Well-known member
from your datasheet reference your transformer wiering is Ok. (you can ohm it out to assure they didn't change their colour scheme) Assuming your transformer is working as shown your meter will read ~36V AC across the outer transformer secondary windings (blue/green). As long as no load is connected, this voltage is probably a little higher and it also will vary with different line voltages. This voltage (this is still AC voltage, so it doesn't matter if you reverse the blue and green secondary wire to your rectifiers AC pins, 50/60Hz later it will be the otherway round anyway) get rectified by a bridge rectifier, resulting in about 50V DC peak across the +/- pins of your rectifier (raw DC-voltage=AC-voltage * 1,414 - 2* 0,7V Diode drop). Between these +/- rectifier pins are your 1000uF reservoir caps, wired in series with your red/brown center tap/0 connection in the middle. (It won't work without this connection) Take care of orientation for these polarized caps. You almost have splitted your feeding raw DC voltage in about 2* 25V, the positive half feeding pin 1 of 7815, the negative feeding pin 2 of 7915. Connect pin 2 of 7815 and pin 1 of 7915 to 0. With connected load (your calrec or prementioned resistors) you will get +15V at pin 3 of 7815 and -15V at pin 3 of 7915 with reference to 0. These regulators will need a heatsink with previous quoted 150mA load per rail and burning 10V differential voltage between reg.in/out. A 100nF cap between close to regulators out and 0 improves stability and transient response, another one between close to reg.in and 0 may be needed if distance between reservoir cap and reg.in exceeds some inches. Although good practice, protection diodes across your reg.in/out and between reg.out and 0 are probably not needed.
Your star ground scheme seems correct. Make shure the IEC ground (safety ground) is always and safe connected to your case.
... now to your camera problem, ... :razz:
Your star ground scheme seems correct. Make shure the IEC ground (safety ground) is always and safe connected to your case.
... now to your camera problem, ... :razz:
