Hi folks
I'm having no end of trouble trying to get my new active crossover setup working.
I have a NAD 1000 Preamp feeding into a DOD 834 Series II active crossover which splits the signal into Hi, Med and Low, which I am then feeding to a Sonance Sonamp 1230 power amp working in bridge mode to give 6 channels.
The problem is that when connected as below, with cables I made that have a mono 6.35mm jack on one end and a male phono on the other, I am only getting sound through one channel.
I've verified with a multimeter that all the cables are working properly.
If I press the stereo-mono switch on the front of the DOD 834, it changes the behaviour, it appears that now, the highs are on one channel and the lows on another.
I'm most confused, I can't for the life of me figure out what is wrong.
I'm having no end of trouble trying to get my new active crossover setup working.
I have a NAD 1000 Preamp feeding into a DOD 834 Series II active crossover which splits the signal into Hi, Med and Low, which I am then feeding to a Sonance Sonamp 1230 power amp working in bridge mode to give 6 channels.
The problem is that when connected as below, with cables I made that have a mono 6.35mm jack on one end and a male phono on the other, I am only getting sound through one channel.
I've verified with a multimeter that all the cables are working properly.
If I press the stereo-mono switch on the front of the DOD 834, it changes the behaviour, it appears that now, the highs are on one channel and the lows on another.
I'm most confused, I can't for the life of me figure out what is wrong.
Attachments
Hmm, it looks like the crossover is faulty as I just went to play with it again and now I get no sound at all. I plugged some headphones into the preamp and verified that is working, so I think the crossover has died and the strange behaviour I was experiencing was it's death throws.
Not sure if I have a clue how or where to start trying to fix the thing...
Not sure if I have a clue how or where to start trying to fix the thing...
For balanced output from the crossover you are supposed to use TRS 1/4" plugs per user manual:
"All inputs and outputs are balanced. Use XLR type male plugs for inputs and female plugs for outputs. For balanced operation using 1/4" phone plug connectors, use only tip-ring-sleeve (stereo) jacks. For unbalanced operation using 1/4" phone plug connectors, use only tip-sleeve (mono) jacks. FOR BALANCED CONNECTION: Wire XLR connections as follows: Pin 2:high Pin 3:low Pin 1: ground or common. FOR UNBALANCED AMPLIFIER CONNECTION: To make an unbalanced connection to the unit's XLR connectors, wire the line connectors as follows: Pin 2:high Pin 3:NO CONNECTION Pin 1:ground. Use tip-sleeve 1/4" phone plug connectors for connection to the amplifiers, wired as follows: tip: high, sleeve: ground"
Mike
"All inputs and outputs are balanced. Use XLR type male plugs for inputs and female plugs for outputs. For balanced operation using 1/4" phone plug connectors, use only tip-ring-sleeve (stereo) jacks. For unbalanced operation using 1/4" phone plug connectors, use only tip-sleeve (mono) jacks. FOR BALANCED CONNECTION: Wire XLR connections as follows: Pin 2:high Pin 3:low Pin 1: ground or common. FOR UNBALANCED AMPLIFIER CONNECTION: To make an unbalanced connection to the unit's XLR connectors, wire the line connectors as follows: Pin 2:high Pin 3:NO CONNECTION Pin 1:ground. Use tip-sleeve 1/4" phone plug connectors for connection to the amplifiers, wired as follows: tip: high, sleeve: ground"
Mike
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Its billed as "3-way stereo, 4-way mono", so if its setup for one it won't be setup for the other I suspect. I wouldn't worry about this.
I'd try cleaning all the switches and pots in the thing, just pushing the mono control might have triggered issues if the contacts are oxidized over time.
Checking the +/-15V rails (I presume its a standard opamp arrangement) too is worth a shot in case the PSU has died.
Hi Michael. I have it wired up with tip-sleeve jacks, the tip of the jack plug is live, the sleeve is ground and it did work fine previously using these cables.
Hi Mark. I'll have to pull it out of the rack and take the lid off and start probing it I think, it's not totally dead as the various LEDs still illuminate when the various buttons are pressed.
Hi Mark. I'll have to pull it out of the rack and take the lid off and start probing it I think, it's not totally dead as the various LEDs still illuminate when the various buttons are pressed.
After leaving it switched off for a couple of hours, I just tried it again and it's started working again, but is still only working through one channel.
When in stereo mode, it is producing all three frequencies on one channel and only some low frequencies at a low level of volume on the other channel (I determined this using the balance knob on the preamp).
Pressing in the stereo-mono button on the crossover to put it into mono mode just removes the low frequencies so that there is music from one channel that has no bass and silence on the other channel.
So it seems to me there is definitely something wrong with the crossover and it may well be the power supply as it stopped working then started working again after being left turned off for a couple of hours.
When in stereo mode, it is producing all three frequencies on one channel and only some low frequencies at a low level of volume on the other channel (I determined this using the balance knob on the preamp).
Pressing in the stereo-mono button on the crossover to put it into mono mode just removes the low frequencies so that there is music from one channel that has no bass and silence on the other channel.
So it seems to me there is definitely something wrong with the crossover and it may well be the power supply as it stopped working then started working again after being left turned off for a couple of hours.
Attachments
The plot thickens
I hooked the preamp upto just the two channels of the amp that are powering the mids without the crossover in the loop and it played music fine for a few minutes then cut out and now I can't get any music at all out of it.
So it looks like the amp is faulty and the crossover may be fine...
I'll have to investigate further by hooking up a different power amp.
I hooked the preamp upto just the two channels of the amp that are powering the mids without the crossover in the loop and it played music fine for a few minutes then cut out and now I can't get any music at all out of it.
So it looks like the amp is faulty and the crossover may be fine...
I'll have to investigate further by hooking up a different power amp.
Well, the crossover is definitely not working as it should - I have hooked up a different power amp, a 2-channel one, and the issue of only getting music through one channel is exactly the same.
So it looks like both the crossover and the Sonance 6-channel amp are faulty.
So it looks like both the crossover and the Sonance 6-channel amp are faulty.
Well, the NAD preamp was faulty, but I've managed to fix that. So now on to the crossover.
I've opened it up and replaced the four caps in the PSU, I also replaced two 1uF electrolytics elsewhere in the circuit with 1uF polyester.
There are fourteen 15uF electrolytics next to the inputs & outputs, they appear to be bipolar as I see no polarity markings on them or on the PCB, so I haven't replaced them as the only suitable caps I have are polarised.
I can't find a service manual for this crossover, so all I can think of to test is the voltage on the two rails supplying the opamps.
I've opened it up and replaced the four caps in the PSU, I also replaced two 1uF electrolytics elsewhere in the circuit with 1uF polyester.
There are fourteen 15uF electrolytics next to the inputs & outputs, they appear to be bipolar as I see no polarity markings on them or on the PCB, so I haven't replaced them as the only suitable caps I have are polarised.
I can't find a service manual for this crossover, so all I can think of to test is the voltage on the two rails supplying the opamps.
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being an older x-over it's quite likely developed cracked solder joints to the 1/4 inch jacks i would remove the pcb and reflow the solders to the jacks.
the behavior described makes me think it's intermittent, i've been lead astray by intermittent faults...
look for simple causes before leaping to cap substitutions.
also if your running unbalanced the phase inversion switches could be a source of trouble creating a short in the inverted position, those are meant for polarity inversion with balanced lines to resolve overall system phase between adjacent bands.
and do clean those i've seen those cause signal drop out.
the behavior described makes me think it's intermittent, i've been lead astray by intermittent faults...
look for simple causes before leaping to cap substitutions.
also if your running unbalanced the phase inversion switches could be a source of trouble creating a short in the inverted position, those are meant for polarity inversion with balanced lines to resolve overall system phase between adjacent bands.
and do clean those i've seen those cause signal drop out.
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Cheers, I already have it apart and the pcb out, so I'll reflow the joints.
I just thought I'd replace the caps while I had it apart as it's about 30 years old and probably would benefit from new caps.
I am indeed running unbalanced, is it sufficient to spray some servisol or similar into the inversion switches and press them on-off a few times?
I just thought I'd replace the caps while I had it apart as it's about 30 years old and probably would benefit from new caps.
I am indeed running unbalanced, is it sufficient to spray some servisol or similar into the inversion switches and press them on-off a few times?
Well, it's working again and sounds great, so it was either the joints on the sockets or the power supply caps or both.
Fixed my preamp yesterday, fixed my crossover today, I'm on a roll....
Something is bound to go wrong now....
Fixed my preamp yesterday, fixed my crossover today, I'm on a roll....
Something is bound to go wrong now....
pessimism is tedious....far better to be an optimist ....while things are good...??
and yep a good quality contact cleaner and some exercise should do the trick, and just to satisfy my curiosity does the state of the phase switches affect operation ?
if nothing else it will affect what happens around the x-over regions with respect to overall phase and can make a difference to imaging and perception just don't do what i do and imbibe scotch in the process....
and yep a good quality contact cleaner and some exercise should do the trick, and just to satisfy my curiosity does the state of the phase switches affect operation ?
if nothing else it will affect what happens around the x-over regions with respect to overall phase and can make a difference to imaging and perception just don't do what i do and imbibe scotch in the process....
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I did clean the switches, but I haven't been able to discern any difference to the sound when they are switched on or off, I think they only affect balanced operation?
I'm currently listening to Creedence Clearwater and sipping some Erdringer weiss bier - it's hot here
A weird thing happened today, some person unknown snuck into my yard and left a half drunk bottle or rum on my kitchen table. We are totally mystified as to who might have done this and why....
Thanks for your advice though, much appreciated.
I'm currently listening to Creedence Clearwater and sipping some Erdringer weiss bier - it's hot here
A weird thing happened today, some person unknown snuck into my yard and left a half drunk bottle or rum on my kitchen table. We are totally mystified as to who might have done this and why....
Thanks for your advice though, much appreciated.
beer... yuck...well so long as it's cold.... well give yourself some time to listen to it and try to keep your source material consistent before passing judgement there's a difference, it's subtle but i've used these and many of there ilk and have found that fliping the mid with respect to the low and high bands makes for an easily noticed difference in imaging (providing no inversions due to overall stage polarity)...P.S.don't drink the rum, after all it's rum...