My experience (opinion):
The damn thing isn’t such bad at all in case of replacing most of it:
1. There is a big improvement by replacing the 6 analog output drivers. That’s because the stock outputs are based on 3 low quality op amps and an electrolytic cap in a row. A, I’m using differential passive outputs with high quality polyprop caps and a relay attenuator for volume control. B, With low impedance power amps (<50kohm) or long cabling (>0.5m) I would prefer a single stage op amp solution (e.g. OPA1632) avoiding AC coupling caps at all. I think Jan’s output board is the only one which is realized this way and it supports additional volume control.
2. There is a big improvement by replacing the 24 MHz clock on the DSP board. That’s because the stock unit is a high jitter solution built with a simple crystal and a HC004. There exist several mods (based on standard oscillators without low PSRR supply) which claim low jitter but aren’t. The only real low jitter solutions are the Tent board and this one http://www.pilghamaudio.com/index.asp?pgid=55
3. It’s hard to find a difference comparing analog and digital inputs of the stock unit. Comparing moded inputs the digital one is clearly better (That’s because you add not only an AD but also a DA converter at the data source.).
A, If you have to use analog inputs it’s best to mod them because the stock unit is build with 3 low quality op amps and an electrolytic cap in a row. Best replacement would be something like an OPA1632 avoiding AC coupling caps. I think Jan’s mod is based on this kind of op amp. http://www.pilghamaudio.com/index.asp?pgid=51
B, Using digital input it’s a big improvement replacing the low quality and erroneous CS8420 of the stock unit. I’m aware of two mods. I’m using this one http://www.pilghamaudio.com/index.asp?pgid=55 because of high PSRR supplies and short cabling.
3. It’s hard to find better DACs than the used AK4393s. I replaced them by AK4396s and believe there is a small improvement although I couldn’t measure.
4. I also replaced the transformer of the digital input but couldn’t hear any improvement. This might be different with 96kHz inputs and using CS8420 although I don’t believe.
5. Based on my experience and opinion PSU modding is the most overestimated although it’s very popular. The DCX supply is a switched type which causes a lot of out of band HF noise (approx 100 kHz). Although you can’t hear this noise it’s not such good for the power amps. The DCX supply provides 5 voltages. 3 of them are used by analog components and therefore sonically relevant. When using digital input and passive outputs only the +9V rail is used for analog components (DACs). Then it’s sufficient to replace the 7805 on the DSP board by something like this http://www.pilghamaudio.com/index.asp?pgid=55 . There exist similar solutions but not with this high PSRR which are more ore less a replacement but not an improvement.
I hope my experience will help you a little bit on ‘your’ way to sonical heaven. But be carefully in believing other people opinions. Trust your own ears and measuring equipment only!
The damn thing isn’t such bad at all in case of replacing most of it:
1. There is a big improvement by replacing the 6 analog output drivers. That’s because the stock outputs are based on 3 low quality op amps and an electrolytic cap in a row. A, I’m using differential passive outputs with high quality polyprop caps and a relay attenuator for volume control. B, With low impedance power amps (<50kohm) or long cabling (>0.5m) I would prefer a single stage op amp solution (e.g. OPA1632) avoiding AC coupling caps at all. I think Jan’s output board is the only one which is realized this way and it supports additional volume control.
2. There is a big improvement by replacing the 24 MHz clock on the DSP board. That’s because the stock unit is a high jitter solution built with a simple crystal and a HC004. There exist several mods (based on standard oscillators without low PSRR supply) which claim low jitter but aren’t. The only real low jitter solutions are the Tent board and this one http://www.pilghamaudio.com/index.asp?pgid=55
3. It’s hard to find a difference comparing analog and digital inputs of the stock unit. Comparing moded inputs the digital one is clearly better (That’s because you add not only an AD but also a DA converter at the data source.).
A, If you have to use analog inputs it’s best to mod them because the stock unit is build with 3 low quality op amps and an electrolytic cap in a row. Best replacement would be something like an OPA1632 avoiding AC coupling caps. I think Jan’s mod is based on this kind of op amp. http://www.pilghamaudio.com/index.asp?pgid=51
B, Using digital input it’s a big improvement replacing the low quality and erroneous CS8420 of the stock unit. I’m aware of two mods. I’m using this one http://www.pilghamaudio.com/index.asp?pgid=55 because of high PSRR supplies and short cabling.
3. It’s hard to find better DACs than the used AK4393s. I replaced them by AK4396s and believe there is a small improvement although I couldn’t measure.
4. I also replaced the transformer of the digital input but couldn’t hear any improvement. This might be different with 96kHz inputs and using CS8420 although I don’t believe.
5. Based on my experience and opinion PSU modding is the most overestimated although it’s very popular. The DCX supply is a switched type which causes a lot of out of band HF noise (approx 100 kHz). Although you can’t hear this noise it’s not such good for the power amps. The DCX supply provides 5 voltages. 3 of them are used by analog components and therefore sonically relevant. When using digital input and passive outputs only the +9V rail is used for analog components (DACs). Then it’s sufficient to replace the 7805 on the DSP board by something like this http://www.pilghamaudio.com/index.asp?pgid=55 . There exist similar solutions but not with this high PSRR which are more ore less a replacement but not an improvement.
I hope my experience will help you a little bit on ‘your’ way to sonical heaven. But be carefully in believing other people opinions. Trust your own ears and measuring equipment only!
Thanks Oetle for you input. It help clarifying a few things.
I was thinking of
1) replacing out put circuit with a single differential op (no electrolytic) configured as a filter /single ended driver.
2) replace the input with a single ended input to differential driver (with 2.5 V Vcom) , gain set so that as much as possible of the ADC range is used (to maximise SNR) given the existing circuit.
all based on OP2134 or suitable high quality OP.
If anybody can point out where to get OPA1632 in EU as a private person, that would be a great help. These makes the input design soo much easier and would replace the standard OP.
Not a electrolytic in the signal path anywhere.
I would design a PCB to put everything on where a volume control can be added later after the output filter but before the output connectors , modular based. New connectors to replace the existing ones.
Later I would attack the digital sections.
I plan to use it mainly with analog inputs.
I was thinking of
1) replacing out put circuit with a single differential op (no electrolytic) configured as a filter /single ended driver.
2) replace the input with a single ended input to differential driver (with 2.5 V Vcom) , gain set so that as much as possible of the ADC range is used (to maximise SNR) given the existing circuit.
all based on OP2134 or suitable high quality OP.
If anybody can point out where to get OPA1632 in EU as a private person, that would be a great help. These makes the input design soo much easier and would replace the standard OP.
Not a electrolytic in the signal path anywhere.
I would design a PCB to put everything on where a volume control can be added later after the output filter but before the output connectors , modular based. New connectors to replace the existing ones.
Later I would attack the digital sections.
I plan to use it mainly with analog inputs.
One of my two units I bought used and that's the one with C/R2. Right now I can't see "Rev" because it's working in my studio, but second one I bought recently (and it's still unmodified) don't have R/C'sjanneman said:
😎 If somebody needs info I can check later for "R/C" version
oettle said:
It will be fair play to say that some of the "recommended" mods are done by you and that you have sales relation with pilghamaudio.com as they resale your mods...
Stef...
You are right, the SRC/clock mod and the Vreg mods are designed by me. But I can promise you that I myself have absolutely NO commercial advantage from any sale but I managed that a small fee is transferred to a school in Ghana. I designed these mods for myself and was asked to share them with others. So I transferred them to Ward because I do not have enough time. I can promise you that my experience report is not based on any commercial issues honestly!
To be a bit more precise about 5% of the selling price of my two mods (SRC/clock and Vreg) is transferred to Gomyoko School in Ghana. I add another 5% to this transfer by sending Ward the PCBs for free. So if you want to see me spending money for charity buy tons of them.
Steff, if you read my experience report carefully you have to admit that I do not prefer any of the existing PSU replacements. I hope you remember that I offered you selling my mods first. I prefer to be fair to the readers of this thread and therefore only recommend valuable mods. But also readers or buyers should be fair to sellers of these mods. It’s a very low quantity business and I assume nobody of the sellers is able to earn a living from this business. So if you think that prices for the mods are too high buy tons of them to bring prices down. You will do a good job not only for other buyers but also for your ears.
Steff, if you read my experience report carefully you have to admit that I do not prefer any of the existing PSU replacements. I hope you remember that I offered you selling my mods first. I prefer to be fair to the readers of this thread and therefore only recommend valuable mods. But also readers or buyers should be fair to sellers of these mods. It’s a very low quantity business and I assume nobody of the sellers is able to earn a living from this business. So if you think that prices for the mods are too high buy tons of them to bring prices down. You will do a good job not only for other buyers but also for your ears.
On http://www.pilghamaudio.com/index.asp?pgid=55 I saw a while ago (and it's still here):
B]Frank has generously decided to donate his payment to the Gumyoko montessori school in Ghana.[/B]
Good boy! I thought - sharing his knowledge and helping others. Great & Thanks!
Ulli
PS: Frank's mods are ordered since I now enjoy DCX2496 even with analog sources thanks to Jan's remote control (superb even with standard PSU etc.). Looking forward...
B]Frank has generously decided to donate his payment to the Gumyoko montessori school in Ghana.[/B]
Good boy! I thought - sharing his knowledge and helping others. Great & Thanks!
Ulli
PS: Frank's mods are ordered since I now enjoy DCX2496 even with analog sources thanks to Jan's remote control (superb even with standard PSU etc.). Looking forward...
I found out about the missing components about a year ago, when Selectronic informed me that their I/O board kit had included the parts, but the original DCX Rev/E did not, so they recommend to exclude the parts.
All good.
All good.
dunno if anyone can help me:
I'm getting quite a bit of noise out of channel #1 (Left Low...LLMMHH) on an unbalanced XLR to RCA. It's kindof a 'white noise' sound but the volume varries on its own with no real uniformity. Sometimes it gets real loud, othertimes soft, and other times it seems not even there. I do not believe it makes a difference whether the DCX is 'warm' or 'cold.'
The amp driving the Mid-bass sends the signal over to another amp driving a single subwoofer. The noise comes through the subwoofer, also.
When I tap or play around with the XLR connector it pops the speaker a bit and then increases or decreases the noise.
I opened up the top to see if it was a bad solder but everything seemed ok (but I really have no clue).
I have checked, rechecked, and resoldered my RCA/XLR cables and the noise remains. I have tested other amps and other speakers.
Channel 2 makes a bit of noise but it isnt nearly as prominent as that out of channel 1.
To provide detail about my setup: It's in my car. I have it plugged into a power inverter. (ground loop nightmare, I know)The input is analog, unbalanced from an ipod. Channels 1 and 2 go to one amp driving the mid-bass', 3,4,5,6 go to another amp to drive the Mids and Highs.
Any help would be appreciated.
I'm getting quite a bit of noise out of channel #1 (Left Low...LLMMHH) on an unbalanced XLR to RCA. It's kindof a 'white noise' sound but the volume varries on its own with no real uniformity. Sometimes it gets real loud, othertimes soft, and other times it seems not even there. I do not believe it makes a difference whether the DCX is 'warm' or 'cold.'
The amp driving the Mid-bass sends the signal over to another amp driving a single subwoofer. The noise comes through the subwoofer, also.
When I tap or play around with the XLR connector it pops the speaker a bit and then increases or decreases the noise.
I opened up the top to see if it was a bad solder but everything seemed ok (but I really have no clue).
I have checked, rechecked, and resoldered my RCA/XLR cables and the noise remains. I have tested other amps and other speakers.
Channel 2 makes a bit of noise but it isnt nearly as prominent as that out of channel 1.
To provide detail about my setup: It's in my car. I have it plugged into a power inverter. (ground loop nightmare, I know)The input is analog, unbalanced from an ipod. Channels 1 and 2 go to one amp driving the mid-bass', 3,4,5,6 go to another amp to drive the Mids and Highs.
Any help would be appreciated.
oettle said:
I haven't read how the conversation came to this point, but for the new readers that didn't go back to read the whole thread here is my opinion:
Frank's SRC/clock mod is THE mod. I would say it is ether single most important and rewarding mod or at least equally important as analog section replacement in DCX2496. There are few of us that did all of the mods that could be done on DCX and interestingly we all share the same opinion regarding Frank's mod.
If you are following this thread from the very start you would see how all this has evolved. I am sure that it is hard for new readers to justify what to do and where to start. Several people here contributed greatly to the quality of what we could do right now, and Frank's contribution stands highly with them.
Yes it is hard to recommend your own product but I would completely agree with Frank's recommendations. Not because of any relationship with Frank, but because of my experience with my unit and mods I have performed. .
On the top of that Frank generously donated proceeds of the sales for the noble purpose. But more importantly he made this outstanding mod available to all of us. Hopefully this gives credit where it is due and well deserved. I hope this also helps new builders in justifying what to do.
AR2
Thanks for the info AR2. I already had chosen the SP series for the upgrade, but just to make sure I had to ask.
Regards
Regards
Two questions ....
Has anyone done an A/B comparison of a well modded DCX vs a DEQX unit? (I own a heavily modded DEQX and have been pretty satisfied with it.)
Is there any place that sells "completely modded" DCX units? My diy skills are abysmal (I wrote code in college, but never touched a soldering iron) ... if so I might convert my other system from passive to active crossovers.
Has anyone done an A/B comparison of a well modded DCX vs a DEQX unit? (I own a heavily modded DEQX and have been pretty satisfied with it.)
Is there any place that sells "completely modded" DCX units? My diy skills are abysmal (I wrote code in college, but never touched a soldering iron) ... if so I might convert my other system from passive to active crossovers.
this link was recently posted on the DCX yahoo group:
http://cgi.audiogon.com/cgi-bin/clt.pl?misceqal&1209507389&clout&3&4&
http://cgi.audiogon.com/cgi-bin/clt.pl?misceqal&1209507389&clout&3&4&
cheaper modding alternative to the DCX2496
Reading this forum, It seems like the DCX2496 is DIY cutting edge once all the mods are done but the cost soon adds up. I'm looking into cheaper easier alternatives at the moment. For instance is there an easier-to-mod off the shelf crossover, where one can just change a set of non-SMD op-amps and still get a good 3-way Linkwitz-Riley active without any noise?
Finding it very difficult to find info on crossovers, which I consider an integral part of setting up an audio system, one that warrants just as much attention as amplifiers or speakers in these forums. Information regarding crossovers seems to be peppered all over the forums and it would be advantageous for it to be more centralized into one forum/category. I have put in a request just need votes.
http://www.diyaudio.com/request/index.php
Reading this forum, It seems like the DCX2496 is DIY cutting edge once all the mods are done but the cost soon adds up. I'm looking into cheaper easier alternatives at the moment. For instance is there an easier-to-mod off the shelf crossover, where one can just change a set of non-SMD op-amps and still get a good 3-way Linkwitz-Riley active without any noise?
Finding it very difficult to find info on crossovers, which I consider an integral part of setting up an audio system, one that warrants just as much attention as amplifiers or speakers in these forums. Information regarding crossovers seems to be peppered all over the forums and it would be advantageous for it to be more centralized into one forum/category. I have put in a request just need votes.
http://www.diyaudio.com/request/index.php
You have a point! The mods often cost more than the DCX.
But I've never had a noise issue when the unit is used as intended. That means heavy attenuation at the power amp. That's how it's done in the pro world where the DCX comes from.
If you're runnng your power amps wide open - well, yeah - it will be noisy. 😉
How much are they down your way? They're about 175 pounds in the UK.
But I've never had a noise issue when the unit is used as intended. That means heavy attenuation at the power amp. That's how it's done in the pro world where the DCX comes from.
If you're runnng your power amps wide open - well, yeah - it will be noisy. 😉
How much are they down your way? They're about 175 pounds in the UK.
I do not know what you are talking about.
With preamp input turned fully up - or digital input, no signal present, connected, I can crank a bryston 4BST fully up on my kef 104/2 and hear ABSOLUTELY no noise whatsoever coming either from the deq or the dcx. I have complete silence.
opps... I wasn't saying that the DCX has noise. What I was saying is "is there any other alternative, that doesn't have noise". I don't have a DCX at the moment. I do have a DEQ2496 though which I use with the optical in/out and that is a superb unit and totally quite. I wouldn't use the analogue in/outs though, well not without heavy and expensive modding 🙁
The cost of a DCX around these parts is between AUD$350-500 depending on where you buy them. There is no one (commercially) doing the mods here though and getting the DIY parts from overseas is costly, especially when you add the shipping costs to Australia.
The cost of a DCX around these parts is between AUD$350-500 depending on where you buy them. There is no one (commercially) doing the mods here though and getting the DIY parts from overseas is costly, especially when you add the shipping costs to Australia.