Konnichiwa,
The 8024 has a very different (and IMHO mushc superior) circuit design. The digital side is notably worse than the DEQ2496 though (sadly).
No idea, never managed to get one myself....
Sayonara
seppstefano said:
The 8024 has a very different (and IMHO mushc superior) circuit design. The digital side is notably worse than the DEQ2496 though (sadly).
seppstefano said:
No idea, never managed to get one myself....
Sayonara
...beg your pardon.
I've just found T. recall to output stages of DEQ similar to DCX... Good news, it seems I have to try the cutter way on its traces (thanks Thierry).
Stefano
I've just found T. recall to output stages of DEQ similar to DCX... Good news, it seems I have to try the cutter way on its traces (thanks Thierry).
Stefano
Kuei Yang Wang said:
..oooopsss, thanks T. After >50 pages, my brain started swapping
Anyway, do you think that it's possible to try a poor man mod (no transformer output stage) and try a simple LPF as suggested by Thierry (If I'm not completely wrong)?
Thanks!
Stefano
Konnichiwa,
ANYTHING is possible.
I doubt it will work unreasonably well though, the Cirrus Logic DAC Chip in the old Behringer DEQ does not like to drive low loads. You are much better off replaching the Op-Amp's with sensible stuff. Ther eis only one Op-Amp per phase anyway (Inputs and outputs) in servo-balanced configuration. Stick a set of OPA627's in the input and something meaty (AD8065/66 or LM6172) into the output stage and you have an excellent item.
Sayonara
seppstefano said:
ANYTHING is possible.
I doubt it will work unreasonably well though, the Cirrus Logic DAC Chip in the old Behringer DEQ does not like to drive low loads. You are much better off replaching the Op-Amp's with sensible stuff. Ther eis only one Op-Amp per phase anyway (Inputs and outputs) in servo-balanced configuration. Stick a set of OPA627's in the input and something meaty (AD8065/66 or LM6172) into the output stage and you have an excellent item.
Sayonara
Great!
Thank you , as always. I guess a new separate PSU for analogue would be a nice addiction. I already opened the boy a did some minor tweak (such as screen some IC's, add some damping to caps and xtal), but still have to understand where to do the surgery to add a separate, perhaps external, PSU.
Ciao, and sorry for my usual flooding of dumb questions.
Stefano
Thank you , as always. I guess a new separate PSU for analogue would be a nice addiction. I already opened the boy a did some minor tweak (such as screen some IC's, add some damping to caps and xtal), but still have to understand where to do the surgery to add a separate, perhaps external, PSU.
Ciao, and sorry for my usual flooding of dumb questions.
Stefano
Hi Stefano,
Unfortunately I haven't the schematics of the DSP8024, although I owned one in the past (replaced with a DEQ2496 now).
I reckon it should be a lot different from the DCX as is doesn't share the same DACs at all.
Now, back to the DCX2496 : I am working on a separate power supply for the analog stage of the DACs (5v analog) because I really do not like what Behringer has implemented there
Have a look at this : Power supply
(sorry about the french, when I have time I'll translate the whole site) :
Good luck,
Thierry
.
Unfortunately I haven't the schematics of the DSP8024, although I owned one in the past (replaced with a DEQ2496 now).
I reckon it should be a lot different from the DCX as is doesn't share the same DACs at all.
Now, back to the DCX2496 : I am working on a separate power supply for the analog stage of the DACs (5v analog) because I really do not like what Behringer has implemented there
Have a look at this : Power supply
(sorry about the french, when I have time I'll translate the whole site) :
Good luck,
Thierry
.
Thierry,
I've been planning the same.
Are you sure this schematic will be sufficient. I like the simplicity and no NFB about it but I'm not sure if you will achieve enough line regulation. Also the output impedance is not very low.
I used shunt reg on my opamps and liked the result a lot. I think I will go either to series regulator + shunt reg route or then even as extreme as ALW regulator at later time.
Ergo
I've been planning the same.
Are you sure this schematic will be sufficient. I like the simplicity and no NFB about it but I'm not sure if you will achieve enough line regulation. Also the output impedance is not very low.
I used shunt reg on my opamps and liked the result a lot. I think I will go either to series regulator + shunt reg route or then even as extreme as ALW regulator at later time.
Ergo
Hi Ergo,
my ear is the ultimate judge. At this stage, I may be wrong, I may be right , honest .
I'll be back here to comment about the results, whatever they are.
Thanks for you attention and help anyway.
Cheers,
Thierry
my ear is the ultimate judge. At this stage, I may be wrong, I may be right , honest .
I'll be back here to comment about the results, whatever they are.
Thanks for you attention and help anyway.
Cheers,
Thierry
What opamp configuration are you using? Can you say if you prefer the passive or active output stage beter?
Many Thanks
Hans
Many Thanks
Hans
Konnichiwa,
The PSU for the 8024 is on the main PCB.
When I had the 8024 I did a number of upgrades, as listed out below:
1) Change all small electrolytic capacitors in the analog stages (they are around the XLR Connectors) for in the end Black Gate N and all others to Sanyo Os-Con, including some of much increased value (330uF/6.3V) around the DAC & ADC.
2) Change All Op-Amp's for LM6172, but in the input section OPA627 or related (AD8610/20, AD8065/66) would have been a better choice. As Behringer used SIL (Single In Line) Op-Amp's I improvised adaters, nowadays you can get readymade SMD to SIL ones from Browndog I believe, if not browndog I saw them somewhere else.
3) The Powersupplies are standard linear on the 8024, so the usual tweaks apply, schottky rectifiers, upgraded regulators ( I used to use LT1033/1085, other options now exist) and upgraded reservoir capacitors (I used Panasonic HFQ).
4) I fitted a pair of Stevens & Billington TX 410LO Line Output TRansformers, I would probably also have fitted input transformer had I not aquired the 2496 instead.... The analog Input of both 8024 and 2496 can be made completely silicon free, using only 1pcs transformer, schematic in my in my technical yahoo group.
Sayonara
seppstefano said:
The PSU for the 8024 is on the main PCB.
When I had the 8024 I did a number of upgrades, as listed out below:
1) Change all small electrolytic capacitors in the analog stages (they are around the XLR Connectors) for in the end Black Gate N and all others to Sanyo Os-Con, including some of much increased value (330uF/6.3V) around the DAC & ADC.
2) Change All Op-Amp's for LM6172, but in the input section OPA627 or related (AD8610/20, AD8065/66) would have been a better choice. As Behringer used SIL (Single In Line) Op-Amp's I improvised adaters, nowadays you can get readymade SMD to SIL ones from Browndog I believe, if not browndog I saw them somewhere else.
3) The Powersupplies are standard linear on the 8024, so the usual tweaks apply, schottky rectifiers, upgraded regulators ( I used to use LT1033/1085, other options now exist) and upgraded reservoir capacitors (I used Panasonic HFQ).
4) I fitted a pair of Stevens & Billington TX 410LO Line Output TRansformers, I would probably also have fitted input transformer had I not aquired the 2496 instead.... The analog Input of both 8024 and 2496 can be made completely silicon free, using only 1pcs transformer, schematic in my in my technical yahoo group.
Sayonara
Hi Ergo.
does that 680r filter with flattish distortion vs frequency slope compare to the rising distortion plot shown earlier when using the 33r filter?
does that 680r filter with flattish distortion vs frequency slope compare to the rising distortion plot shown earlier when using the 33r filter?
AndrewT,
I chose the 680 ohm as the data sheet specifies the lowest acceptable AC load to be 600 ohm. I have not tried 33 ohm but I do suspect that that is what caused the rising distortion figure on that graph.
mbcouple,
I have included the principal schematic I use for opamp outputs. As you can see I have avoided using the opamp as filter. I use it only as a gain device and all the filtering is done before and after the opamp with RC filters.
I have now listened to the opamp version for two weeks (I listened the passive RC for half a year) and I do like it better than the passive version.
On technical side I have now fully working volume control right at DCX output, I have more gain (passive version did not have enough in my case), I have better load driving capability.
As for sound - the most I was bothered by the highs with passive mod. All metallic hi hats and other instruments were too sharp and tiering if listening session was long. This has improved a lot. I can now even turn the level up 1dB on my Millennium tweeter without getting the same disturbing feeling.
Overall I really believe I have achieved to keep all the good that came with the passive mod.
I chose the 680 ohm as the data sheet specifies the lowest acceptable AC load to be 600 ohm. I have not tried 33 ohm but I do suspect that that is what caused the rising distortion figure on that graph.
mbcouple,
I have included the principal schematic I use for opamp outputs. As you can see I have avoided using the opamp as filter. I use it only as a gain device and all the filtering is done before and after the opamp with RC filters.
I have now listened to the opamp version for two weeks (I listened the passive RC for half a year) and I do like it better than the passive version.
On technical side I have now fully working volume control right at DCX output, I have more gain (passive version did not have enough in my case), I have better load driving capability.
As for sound - the most I was bothered by the highs with passive mod. All metallic hi hats and other instruments were too sharp and tiering if listening session was long. This has improved a lot. I can now even turn the level up 1dB on my Millennium tweeter without getting the same disturbing feeling.
Overall I really believe I have achieved to keep all the good that came with the passive mod.
Attachments
Ergo,
Does the second resistor in the "T" on the op-amp output represent your load resistance?
Cheers,
Davey.
Does the second resistor in the "T" on the op-amp output represent your load resistance?
Cheers,
Davey.
Davey,
Yes. I have 100 ohm in series with output and cap to ground and the other resistor is a 10k load.
I will evaluate and listen to the DCX for a few more weeks and if all works stable and I'm still happy with the sound I will post the schematic with values and all.
Ergo
Yes. I have 100 ohm in series with output and cap to ground and the other resistor is a 10k load.
I will evaluate and listen to the DCX for a few more weeks and if all works stable and I'm still happy with the sound I will post the schematic with values and all.
Ergo
DCX2496 availability
Sorry for diverting the subject a bit here...but. What the heck is going on with the DCX and availability. I'm in the States and no major distributor I've found yet has any of these things to sell. A quick look at musiciansfriend.com made mention of units being available in MAY 2006!!!
I've recently committed to using a couple of these things in a sound install.
Does anyone have any idea what's going on here and if there is a secret stash in some far flung location....🙂
Thanks
MEB
Sorry for diverting the subject a bit here...but. What the heck is going on with the DCX and availability. I'm in the States and no major distributor I've found yet has any of these things to sell. A quick look at musiciansfriend.com made mention of units being available in MAY 2006!!!
I've recently committed to using a couple of these things in a sound install.
Does anyone have any idea what's going on here and if there is a secret stash in some far flung location....🙂
Thanks
MEB