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Hissing from DCX2496
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JRJ View Drop Down
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    Posted: 06 December 2023 at 2:18pm
My DCX2496 (from 2005) has a quite loud hissing on some channels.
Input A - not so much
Input B - pretty much
Input C - too much

Doesn't seem to matter that much how I route the inputs/outputs, it's the inputs that's making the majority of the hissing.

Is it the common problem with the flat cables perhaps? Visually they look OK, and when bending them a bit back and forth the sound popped/sparkled a bit at first, but the hissing was still there.
Also read some stuff about changing the caps on the power supply board?

Seems to be a ton of problems with "frying egg" sound, but I'm not really sure what that is supposed to sound like...? Smile
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Points: 7752 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 06 December 2023 at 6:23pm
I think that the "frying egg" noise is a general crackling and hissing on the unit.

One of my DCX first lost Input A, which wasn't too big a problem, as I just swapped to B & C, but then O/P 6 started crackling, so I replaced the main flat cable and that seemed to cure all the problems, although it's been a while since I've used that unit. At the moment, it's just an emergency spare.

So the bottom line is the main flat cable causing these issues. Best to replace - and solder in rather than use the multipin connectors.
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Conanski View Drop Down
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Points: 2757 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 06 December 2023 at 11:20pm
Originally posted by JRJ JRJ wrote:

My DCX2496 (from 2005) has a quite loud hissing on some channels.
How are you using or planing to use this processor?  It does have a bit more self noise than some other processors but in use for PA applications it not a big deal once everything is setup.

Also note that whatever channel is setup to pass high frequency content and has HF drivers attached will exibit more hiss, that could be some or all of the outputs depending how the processing is setup.

Originally posted by JRJ JRJ wrote:

Doesn't seem to matter that much how I route the inputs/outputs, it's the inputs that's making the majority of the hissing.
Exactly how are you coming to that conclusion? It's not possible to isolate the inputs and listen to them alone.
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certainly I would check the power supply for the usual bulging or leaking capacitors especially if the unit has been used in an installation where it's spent most of its time powered up: capacitors lifespans are rated by a product of temperature and time.

Also the obvious thing that creates spurious noise is liquid damage or corrosion.

Replacing both ribbons and their IDC pluggable and pcb transition connectors is the next thing, if you're confident you can do it without damaging the pcb. Proper, branded cable and connectors eg fujitsu, 3M, harting. TE etc are the way, not generic rubbish from amazon, aliexpress or other outlet. The frying egg noise is due to imperfect contact between the IDC forks and the ribbon cores. Great for digital connections on IDE hard drives but for audio the contact must be consistently intimate.
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Remove and re-seat the ribbon cables on the inside of the unit. Often hissing/frying egg sound from these is due to corrosion on the contacts of the internal ribbon cables and taking them out and putting them back in will fix it. This is a known issue with these units.
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JRJ View Drop Down
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Points: 37 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JRJ Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2023 at 7:54am
Originally posted by Earplug Earplug wrote:

I think that the "frying egg" noise is a general crackling and hissing on the unit.

One of my DCX first lost Input A, which wasn't too big a problem, as I just swapped to B & C, but then O/P 6 started crackling, so I replaced the main flat cable and that seemed to cure all the problems, although it's been a while since I've used that unit. At the moment, it's just an emergency spare.

So the bottom line is the main flat cable causing these issues. Best to replace - and solder in rather than use the multipin connectors.

Ok, so both input C and output 6 came back to life after that?
Seems to be a ton of info about the flat-cable-issues with the DCX2496, so that can surely be my problem as well.
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JRJ View Drop Down
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Points: 37 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JRJ Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2023 at 8:02am
Originally posted by Conanski Conanski wrote:

How are you using or planing to use this processor?  It does have a bit more self noise than some other processors but in use for PA applications it not a big deal once everything is setup.

Also note that whatever channel is setup to pass high frequency content and has HF drivers attached will exibit more hiss, that could be some or all of the outputs depending how the processing is setup.

Originally posted by JRJ JRJ wrote:

Doesn't seem to matter that much how I route the inputs/outputs, it's the inputs that's making the majority of the hissing.
Exactly how are you coming to that conclusion? It's not possible to isolate the inputs and listen to them alone.

I'm just using it in my hobby-rig for garden parties, school-discos, and similar.
15" sub and 12"/2" tops so no hifi-rig but still annoying with the hissing.

No I haven't isolated the inputs from the outputs, but when changing the routing between the inputs/outputs in the way it's possible in the setup menu, I got the impression it was more related to the inputs but I haven't done any more testing then that.
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JRJ View Drop Down
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Points: 37 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JRJ Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2023 at 8:04am
Originally posted by kedwardsleisure kedwardsleisure wrote:

certainly I would check the power supply for the usual bulging or leaking capacitors especially if the unit has been used in an installation where it's spent most of its time powered up: capacitors lifespans are rated by a product of temperature and time.

Also the obvious thing that creates spurious noise is liquid damage or corrosion.

Replacing both ribbons and their IDC pluggable and pcb transition connectors is the next thing, if you're confident you can do it without damaging the pcb. Proper, branded cable and connectors eg fujitsu, 3M, harting. TE etc are the way, not generic rubbish from amazon, aliexpress or other outlet. The frying egg noise is due to imperfect contact between the IDC forks and the ribbon cores. Great for digital connections on IDE hard drives but for audio the contact must be consistently intimate.

OK, I'll check the caps as well then.
I bought it used so I have no idea how it has been used in the past.
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JRJ View Drop Down
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Points: 37 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JRJ Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2023 at 8:08am
Originally posted by fat_brstd fat_brstd wrote:

Remove and re-seat the ribbon cables on the inside of the unit. Often hissing/frying egg sound from these is due to corrosion on the contacts of the internal ribbon cables and taking them out and putting them back in will fix it. This is a known issue with these units.

I did remove the flat cable contacts and fiddled a bit with the cables, and it got a bit better but it's still hissing quite a bit.
Stupid thing that you can't unplug both ends of it, I'll remove the PCB and see if I dare bring out the soldering iron...
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Originally posted by JRJ JRJ wrote:

Originally posted by Earplug Earplug wrote:

I think that the "frying egg" noise is a general crackling and hissing on the unit.

One of my DCX first lost Input A, which wasn't too big a problem, as I just swapped to B & C, but then O/P 6 started crackling, so I replaced the main flat cable and that seemed to cure all the problems, although it's been a while since I've used that unit. At the moment, it's just an emergency spare.

So the bottom line is the main flat cable causing these issues. Best to replace - and solder in rather than use the multipin connectors.

Ok, so both input C and output 6 came back to life after that?
Seems to be a ton of info about the flat-cable-issues with the DCX2496, so that can surely be my problem as well.


Input A, but yes - changing the cable sorted out all the problems.

Saying that, as Mr. Edwards mentioned, also take a look at the caps on the PSU. You never know...
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Xoc1 View Drop Down
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Points: 485 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Xoc1 Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2023 at 1:07pm
Take care inside the DCX - as the Switch mode PSU has some exposed capacitor tops that are at high voltage. 
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Points: 8 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Stigbergets_Sweden Quote  Post ReplyReply Direct Link To This Post Posted: 02 January 2024 at 12:19pm
Has anyone bricked a eeprom with the Ultradrive Pro DCX2496? Mine seems to have stopped responding and won't boot, I have another unit and can swap out the memory chip then the unit starts without problem.
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