Ste,
the low pass filters are correctly set up to achieve LR4.
The high pass have an error in that the 47k is not equal to 100k/2 This will change the Q of the filters
100k in many of the filters will give rise to avoidable noise.
You have 3 cascaded +6dB gain stages on all the outputs. This is an extra +18dB of gain. Do you need any of that extra gain? This will create avoidable noise.
You have no RF filtering on the input.
the low pass filters are correctly set up to achieve LR4.
The high pass have an error in that the 47k is not equal to 100k/2 This will change the Q of the filters
100k in many of the filters will give rise to avoidable noise.
You have 3 cascaded +6dB gain stages on all the outputs. This is an extra +18dB of gain. Do you need any of that extra gain? This will create avoidable noise.
You have no RF filtering on the input.
You have 100k & 47k in the high pass filters.
For a Q=sqrt(2) to give a Butterworth roll-off you should have 100k & 50k.
Cascading two Butterworth 2nd order filters is what gives you the LR4.
Compare to your low pass filters. You have single and double capacitors for that exact 1:2 ratio that is needed for the correct Q.
For a Q=sqrt(2) to give a Butterworth roll-off you should have 100k & 50k.
Cascading two Butterworth 2nd order filters is what gives you the LR4.
Compare to your low pass filters. You have single and double capacitors for that exact 1:2 ratio that is needed for the correct Q.
My dcx has started to do the digital input cs8420 notch filter bug every time I use it lately. The ribbon cable doesn't seem to be the cause, even though that was faulty and causing dropouts before i reseated it. As far as I can tell there isn't an easy fix for this bug, is there? It's about to go out the window and be replaced with a minidsp.
well 2 ways,1 get a dac board off ebay and patch it in or 2 replace the chip,
I stood the board vertical and brushed the legs(pins) with a small torch ,the chip will fall off when it gets legs hot enough ,or cut the legs and pull them off one at a time ,A used motherboard is a good practice before the real deal,
works as it should now ,might also replace the caps around that area with oscons,Good luck!
NS
Cheers NS. I have an old Ebay DAC here that uses a CS8416. What's involved in patching that in to the dcx? Thanks heaps for the help
Edit: similar to this? http://freerider.dyndns.org/anlage/images-Behringer-Input-Stage/k_IMGP2541.html
Edit: similar to this? http://freerider.dyndns.org/anlage/images-Behringer-Input-Stage/k_IMGP2541.html
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Cheers NS. I have an old Ebay DAC here that uses a CS8416. What's involved in patching that in to the dcx? Thanks heaps for the help
Edit: similar to this? Neue Eingagsstufe für DCX2496
I replaced the chip,but here's what I have for the add on CS board,
I did some serches and also yahoo groups got alot of info,Look up Linuxworks on this site.
here's a pic to wire it!
NS
Attachments
Thanks NS. I think smd work is probably beyond me right now as I don't have my gear set up. So, first I will try a new usb-spdif board and if that doesn't fix the issue I will have to go down the minidsp route. The usb spdif board I currently have is causing all sorts of interference so there is a chance it is faulty or poorly built. It completely wipes out some tv stations.
Hi,
I haven't had that happen ,Guessing,bad eprom,I have a few extra's, or a bad connection ,I would remove the eprom and reinsert it and that gray flat interconnect cable is known to give problems,oopps one more maybe a button sticking(page buttons),just push all the buttons a few times and see if any of them feel different,If the keypad has been hit hard that can damage the membrane ,calculators,Remote controls, do the same thing sometimes usually the most used key,I have found coke and coffee inside them ,lol go figure right?
Good luck!
NS
I'm trying to fit a usb/spdif adapter (search ebay for "usb spdif 96khz", the small square one) and it kind of works but I have several issues:
1. The audio stream drops out every couple of minutes, especially if some electric device is being switched on nearby. I've tried all sorts of shielding schemes with no success. Sometimes these dropouts result in digital input lockout (the dull sound), but it may randomly recover with another dropout, which also indicates the DCX itself is getting contaminated with EMI.
2. DCX has trouble syncing at max volume, even more so at higher sampling frequencies. It works OK at 44kHz/half volume. If I dial anything above ~70% in software, I sudenly get raunchy and distorted sound. With 96kHz it's hard to even get it in sync, highly dependant on the cable, USB port and the music content (again, mainly level).
What I have noticed:
1. I suspect my PC PSU is far from ideal (polluted USB bus is driving the adapter crazy and possibly injecting HF noise into the DCX itself) as these problems seem to be absent when hooked up to a laptop.
2. The Tenor chip itself is not to be blamed as I have an ODAC plugged in the same system and it works flawlessly.
List of mods so far:
1. Changed the DCX digital input resistor to ~75 ohms. I have not tried to bypass the ribbon cable/relays yet.
2. Tweaked the adapter board a little by replacing caps for bigger ones and placing an RC filter on the VCC line.
3. TODO: rewire CS8420 for slave/slave operation and plug the adapter straight in through I2s. It should definitely help with the sync issue as the SPDIF stream looks somewhat "soft" on a scope, I suspect the driver circuit is not implemented very well. Not sure if it will help with the random dropouts as these may be caused by any element in the chain.
4. TODO: before doing any serious replacements or investments in UPS I decided to try the ADUMxxxx USB isolator thingy, it should arrive in a week or so.
Until then, could you guys suggest any tweaks or hacks I could try?
1. The audio stream drops out every couple of minutes, especially if some electric device is being switched on nearby. I've tried all sorts of shielding schemes with no success. Sometimes these dropouts result in digital input lockout (the dull sound), but it may randomly recover with another dropout, which also indicates the DCX itself is getting contaminated with EMI.
2. DCX has trouble syncing at max volume, even more so at higher sampling frequencies. It works OK at 44kHz/half volume. If I dial anything above ~70% in software, I sudenly get raunchy and distorted sound. With 96kHz it's hard to even get it in sync, highly dependant on the cable, USB port and the music content (again, mainly level).
What I have noticed:
1. I suspect my PC PSU is far from ideal (polluted USB bus is driving the adapter crazy and possibly injecting HF noise into the DCX itself) as these problems seem to be absent when hooked up to a laptop.
2. The Tenor chip itself is not to be blamed as I have an ODAC plugged in the same system and it works flawlessly.
List of mods so far:
1. Changed the DCX digital input resistor to ~75 ohms. I have not tried to bypass the ribbon cable/relays yet.
2. Tweaked the adapter board a little by replacing caps for bigger ones and placing an RC filter on the VCC line.
3. TODO: rewire CS8420 for slave/slave operation and plug the adapter straight in through I2s. It should definitely help with the sync issue as the SPDIF stream looks somewhat "soft" on a scope, I suspect the driver circuit is not implemented very well. Not sure if it will help with the random dropouts as these may be caused by any element in the chain.
4. TODO: before doing any serious replacements or investments in UPS I decided to try the ADUMxxxx USB isolator thingy, it should arrive in a week or so.
Until then, could you guys suggest any tweaks or hacks I could try?
Hi WXN,
Sounds like you have a bunch of noise EMI or similar on your signal,Got a scope?
The laptop runs on batteries not a switching power supply that's why it sounds better with it,
I would think,the isolator you got coming should fix it,
Their is alot on this site about cleaning up signals and computer sound sources,
sorry I can't be of better help.
Sounds like you have a bunch of noise EMI or similar on your signal,Got a scope?
The laptop runs on batteries not a switching power supply that's why it sounds better with it,
I would think,the isolator you got coming should fix it,
Their is alot on this site about cleaning up signals and computer sound sources,
sorry I can't be of better help.
