Dcx2496 v minidsp for dipole xover/eq

[sfdoddsy]

I've just moved house which has meant dismantling and reassembling my rather complex Orion/Phoenix/Bob system.

As I do this I am pondering alernatives.

I'm still not tempted to change its essential nature, or the drivers. And whilst unlike some I don't have any major issues with the sonic quality of the dcx, I hate its general flakiness. I have two now (and have gone through others) because of intermittent failures related to its poor design.

So I'm intrigued by the Minidsp.

It appears to do everything in terms of xover and EQ that the dcx does, but without the reliability issues.

And it is cheaper.

Davey has tried it in a similar setup to mine, as has Gainphile, but I'm wondering how others have found the stability (most importantly) and the noise.

It'll be fed from the variable out of a prepro. i used to listen loud to (on occasion) big orchestral, organ and reggae in a very big room (650sf with 15ft ceilings) but the new one is much smaller. At the moment I have balanced amps, but their Euroblock connections annoy me so much they may also be looking at a new owner.

PS, did I mention how much I hate Euroblock connectors? They are fiddly, fragile and pick up the noise balanced operation is supposed to remove. They suck.

[fjhuerta]

I'm very curious about this device, too. It seems to do many very cool things... a dipole may be awesome with it.

[sfdoddsy]

I'm very curious about this device, too. It seems to do many very cool things... a dipole may be awesome with it.

i don't think it does anything the dcx can't do, at least with the plug in I'd use. But unlike altenatives such as the Driverack it does have dipole friendly shelving filters available.

I'd just like to avoid the infrequent but intensely annoying freezes, channel drop outs and fatal power supply issues that even the service guys say are endemic with the dcx.

That said, the potential for a cheapish all digital path right up to the speaker terminals has a certain intellectual appeal.

[Saurav]

Is it really cheaper? I figure you'll need 2 DSP boards and maybe one digital input board, add in plugins and powersupply / chassis, and you're pretty much at the cost of a DCX, aren't you?

I've been curious about miniDSP too. I suspect the overall gain structure / noise levels would be better than with a DCX. But I have an Emotiva pre-pro for a 6-channel volume control, so I'm not sure if that matters any more for me.

In short, I'm intrigued, but it seems like a somewhat sideways move, so I'm not sure I can justify it. I read some comment somewhere saying the downstream VC wasn't needed any more. No details on how you should implement volume control, especially with a digital input. If I could sell off the DCX and the LMC, that would make the miniDSP an overall less expensive solution.

miniDSP also has the potential to implement more complex transfer functions with the custom biquad programming, but I didn't find any plug-and-play recipes out there that I could use for anything.

[Rudolf]

I read some comment somewhere saying the downstream VC wasn't needed any more. No details on how you should implement volume control, especially with a digital input. If I could sell off the DCX and the LMC, that would make the miniDSP an overall less expensive solution.

They say in the miniDSP kit data sheet, that it's got connections for a 10 kOhm pot to control volume. The same pot can control as many DSPs as you want. AFAIK this volume control is digital and placed in the output stage.

[Saurav]

Thanks for that info. It would be hypocritical of me to turn my nose up at digital volume control, since I have various gain levels set in my DCX to match the driver sensitivities

For me, there's one more reason why the miniDSP is interesting. I really have 7 channels - a summed subwoofer. I send the woofer outputs of the DCX to a CX2310 analog XO, which does the woofer-subwoofer XO, and the summed subwoofer output. So that's a 3rd box that I could potentially get rid of. The miniDSP 4-way plugin won't work for me, but I could use a combination of 2-way and 2.1 plugins:

Board 1 (2-way or 2.1 plugin):
Tweeter - left
Tweeter - right
Midrange - left
Midrange - right

Board 2 (2.1 plugin):
Woofer - left
Woofer - right
Subwoofer

Definitely something to think about. Hmm, I'd also need a remote control kit for that 10kOhm pot. I used to have a DIY volume control, but then I got used to remote control with the LMC-1

[gainphile]

In terms of functionality, MiniDSP wins outright. Just think about Linkwitz transform or cascaded filter

Recently we in Melbourne compared MiniDSP vs. DCX vs. DCX Modded (the mod itself is $1000!) and I could hear no difference. This is instant switching.

Other participants prefer the MiniDSP sound.

A 4-way MiniDSP cost half of DCX (which is only 3-way).

So I'd say get the MiniDSP.

[Saurav]

A 4-way MiniDSP cost half of DCX (which is only 3-way).

Stereo? With digital and analog inputs? The last time I checked, I thought the prices were pretty comparable. But I might have misunderstood what I'd need to buy to make my setup work.

[gainphile]

Stereo? With digital and analog inputs? The last time I checked, I thought the prices were pretty comparable. But I might have misunderstood what I'd need to buy to make my setup work.

Stereo, 4-way, analog input. Basically:

2x MiniDSP kit: $200
1x advanced 4-way plugin: $10

Total $210. Perhaps add $15 for regulated power supplies.

Ok.. but the case could cost $500

[Davey]

You'd need at least one (easier to implement connection-wise with two) miniDIGI board to provide digital input capability. So, another $140.00 on top of $210.00 gets you to $350. (Getting in the neighborhood of the DCX.)

The miniDSP has some possible pitfalls the DCX doesn't' have.......but also vice-versa. They're kind of aimed at different user bases, so a value comparison gets a little tricky.

Cheers,

Dave.

[Rick Craig]

If you don't mind having amplification included I would consider the Digmoda units.

[Saurav]

That's the math I ended up with, it's about the same cost-wise.

The miniDSP has some possible pitfalls the DCX doesn't' have.......but also vice-versa

Could you elaborate on this?

[sfdoddsy]

You'd need at least one (easier to implement connection-wise with two) miniDIGI board to provide digital input capability. So, another $140.00 on top of $210.00 gets you to $350. (Getting in the neighborhood of the DCX.)

The miniDSP has some possible pitfalls the DCX doesn't' have.......but also vice-versa. They're kind of aimed at different user bases, so a value comparison gets a little tricky.

Cheers,

Dave.

Digital input is tempting, but I'm pretty sure my prepro won't output DD and DTS via the digital out and I use my system for video as well.

[gainphile]

This was the comparo that we did down under:

http://redspade-audio.blogspot.com/2010/12/active-crossover-listening-tests.html

We did it twice at two different venues & system.

We also tested using instant-switching direct wire vs. DSP (Signal => ADC => DAC) and it was transparent. Hence I really don't think digital input is a great requirements.


And this is my summary when investigating the functionalities:

Slopes (obviously) ... ok
Phase alignment/allpass filters ... ok (using delay)
Notch filters ... ok
Channel level ... ok
Linkwitz Transform ... ok (thanks to the netherlands DIYers!)
Shelving Lowpass filter ... ok
Master volume control ... ok
Cascaded filter stage topology ... ok

btw. In Australia, the DCX cost $450-$500, so a bit different story.

[Saurav]

Hence I really don't think digital input is a great requirements.

Well, my source is a ROKU player, so either I use its crappy internal analog section, or add a DAC (which I have, currently lent out to a friend) just to have the XO ADC it again, or just go digital in, which seems the most efficient. For the phono stage I'd use the analog inputs, of course.

[Davey]

That's the math I ended up with, it's about the same cost-wise.

Could you elaborate on this?

Well, how much time do you have? I guess I can hit upon a few of the high points.

Volume control and signal levels:

DCX: It's pretty well known the DCX should be utilized with a downstream volume control to minimize noise from the output stages and to better position signal levels in the upper part of the dynamic range of the unit. This requires a complicated six-channel volume control of some sort. (Possibly costly if not DIY-inclined.)
Also, if this volume control is not used with both sides of the DCX balanced outputs then component tolerances in the analog output stages yield poorly matched levels between the six output channels.

miniDSP: The miniDSP has much lower output noise levels and direct connection to power amplifiers is the preferred configuration. The miniDSP has a system volume control capability by wiring a potentiometer into the architecture. However, I've found it to be essentially useless because it's near maximum most of the time.....in my usage.
The signal levels of the miniDSP are limited to 0.9 volts RMS input AND output. They provide a jumper switchable -7.3db pad at the input of the board for those users who plan to apply their source directly. Unfortunately, many CD's or other sources are recorded at signal levels low enough so this 7.3db of attenuation is too much. Thus you can't get enough volume from the unit.
Switching the input jumper to 0db removes the 7.3db attenuation but means the unit will voltage clip with CD's or other sources outputting typical 2.0-2.5 maximum RMS levels.
I settled on using the jumpers in the 0db position and providing my own volume control upstream of the miniDSP. (That works pretty good.)
Utilizing a digital input can partially alleviate this issue, but possible clipping still needs to be fully understood.

The DCX notifies you of clipping with bright red indicators on the output channels. The miniDSP has no indicators unless you're laptop is connected and monitoring realtime.

More? (I can type some more tomorrow if interested.)

Cheers,

Dave.

[Saurav]

Definitely interested. The points you raise about gain matching / clipping are interesting. I use an Emotiva pre-pro as my downstream volume control, so that's a sunk cost for me. I also regularly use about 20dB of volume range on that, so I don't think I could use an XO without any volume adjustment capability

[Deward Hastings]

I don't think I could use an XO without any volume adjustment capability

I don't understand that . . . once the crossover is properly matched to the amp/driver combination (so that output clipping occurs at the same point as either amplifier clipping or driver overexcursion, whichever comes first) what is there to adjust? That's a one-time setting that gives maximum SNR from the DAC (and everything following). Set the gain structure after the crossover once, and then forget it . . .

[Saurav]

That wasn't too clear. I was responding to this:

The miniDSP has a system volume control capability by wiring a potentiometer into the architecture. However, I've found it to be essentially useless because it's near maximum most of the time.....in my usage.

I took that to mean that Davey runs his system with no volume control at all. That's what I was saying I couldn't do. But I missed the part later where he says he has volume control upstream of the XO.

[gainphile]

The gain structure is important. I made the mistake of buying the RevB (or A??) which had the lower input sensitivity. Hence not enough juice . But nothing that an op-amp can't fix :P

Buy the 0db (the higher sensitivity) one and use Pot to control. Much more elegant.

I tried the MiniDSP digital volume control and did not like it that time. Need to try again.

[Paul Spencer]

Looks like you guys are getting invaded by the Aussies now! ....

I was one of the ones that thought MiniDSP was just slightly better, but they were so close that it could have been "setup related." The sound isn't really a big issue, although it was noted that MiniDSP had a lower noise floor.

I bought a 2nd hand DCX for $250, about the cost of two boards shipped, then add on $60 for a case and perhaps $20 for other bits.

DCX will do much longer delays required to time align with subs and allows easy realtime adjustments without a PC. It also comes with balanced inputs and dynamic EQ filters and a few other features that aren't really needed. The auto align is also very nifty.

However, DCX mostly only adds things you don't need and it has that Vegas flashing lights look that doesn't quite feel right in a high end system. You can easily buy a nice box for MiniDSP and even put it in the same box as some amp modules - less cables and clutter and a much cleaner look.

Digital inputs also favour MiniDSP because they are intended for consumer equipment. DCX doesn't as it will clip with digital SPDIF inputs even though it can be set to accept them.

I actually have both units, but I find DCX a bit more convenient to use (no laptop). I plan to use MiniDSP for active surrounds put in the same box as 4 amp channels. Very simple. I'll have 4 pole speakon connectors to keep it fool proof. That's a very simple solution.

I've written about all the more popular active options here:

http://redspade-audio.blogspot.com/2010/06/active-options.html

One thing I would miss about DCX is being able to quickly tweak up the bass level on the fly if a movie is bass heavy or some music is bass shy.

I think the choices comes down to what you find more appealing in your system. I think most guys would be happier with MiniDSP. It's cheaper for what it offers that people will really use. It will usually mean a more attractive package and the biquads make it generally more powerful. There's really just two things I'd like to see - one is longer delays (more like 30ms) and some more advanced phase correction. But for that you need to spend quite a bit more on systems like DEQX or PC based setups with pricey sound cards.

[Deward Hastings]

There's really just two things I'd like to see - one is longer delays (more like 30ms) and some more advanced phase correction.

Check out the (relatively) new rear/center plug-in

http://www.minidsp.com/images/documents/Product%20Brief-Rear-Center%20channel%20plug-in.pdf

It's got the delay . . . I'm wanting PEQ instead of the GEQ, though, to better do active room-mode cancellation. I'd also like to be able to put the two-channel portion of the delay on the inputs rather than the outputs . . .

[Rudolf]

Digital inputs also favour MiniDSP because they are intended for consumer equipment. DCX doesn't as it will clip with digital SPDIF inputs even though it can be set to accept them.

I believe that this is a misunderstanding. The DCX input is 24 bit wide and it can't "clip" input signals which are no wider than 24 bit by definition.

With SPDIF inputs the red "CLIP" lights in the input section don't signal clipping AFAIK, but usage of the last bit. You can drive the DCX into digital distortion if you apply positive gain or EQ in the digital input section. This is a big no/no of course.

[Paul Spencer]

Rudolf,

On my Bluray player it went into clipping unless I had the level attenuated to around 3%! The sound was poor. It seems the level was just too high. I have heard others have had the same problem, but I haven't looked into it.

[sfdoddsy]

Well, I'm going to grab a couple. Aside from the general DCX flakiness mentioned above, I'd prefer to adjust the gain via my prepro rather than using the attenuators on my amps.

Thanks to the DCX's input and output requirements I have been using balanced gear for the past few years to try and simplify hookup, but it really isn't worth the hassle.

Not to mention that I am now pretty much all Mac and the Behringer software isn't Mac friendly.

And I hate the lack of support for the DCX from Behringer etc etc.

Assuming all is fine with the Minidsp, I'll keep one of my DCX's as a backup.

[Rudolf]

Paul,

I have a hard time to understand what happened in your case. Digital formats are standardised - in bit processing as well as in electrical connection values. If you exit the Blue ray player with a non-encoded PCM audio signal at a digital-stereo-out socket (probably cinch or Toslink), you would either get the full quality signal or none at all. I don't see any means where a digital signal could be attenuated at the exit of a BR player or the input of the DCX while INcreasing its quality at the same time.

[Davey]

Paul,

Are you referring to the clipping indicators on the DCX input channels? Those are not 100% reliable to indicate actual waveform clipping within the DCX digital architecture or analog output portions.

The indicators on the six output channels are your guides. If those are flashing red you are indeed waveform clipping. If they're not you're not. Guaranteed.

(The DCX has been around for years now, but I still sense that many people are misusing it or misunderstanding aspects of its operation.)

Cheers,

Dave.

[gainphile]

but I'm wondering how others have found the stability (most importantly) and the noise.

Seems like this had not been answered?

Stability: Perfect. Never "hangs" or whatever. Just set and go...

Noise: None that I can attribute it to.

[penngray]

Definitely interested. The points you raise about gain matching / clipping are interesting. I use an Emotiva pre-pro as my downstream volume control, so that's a sunk cost for me. I also regularly use about 20dB of volume range on that, so I don't think I could use an XO without any volume adjustment capability

FWIW, I have 3 MiniDSPs and Im ordering a 4th (balanced unit). Im getting rid of my DCXs.

I love to finally get rid of the DCX with all its pro audio nightmares (XLR to RCA, hum issues, high gain outputs increasing ribbon and horn hiss levels, gain structure nightmares). Prototyping and tweaking is still in the DCX favor but I can not think of anything else the DCX does other then 6 channels vs 4 channels. Remember the DCX takes Biquad filters, you can create a 96dB Slope if you want, you can cascade filters. Subwoofer LT circuits, HPF at 10Hz.....Its what we have wanted for years....BEST product of 2010.

The MiniDSP can be completely hidden too...no ugly DCX looks and lights.

If we could get someone to attach a linear phase correction device to the MiniDSP then we can have a tool that rivals the DEQX in terms of XO functionality.

My main system will be MiniDSP until the DEQX express is sold used on audiogon for under $1200.

[penngray]

Seems like this had not been answered?

Stability: Perfect. Never "hangs" or whatever. Just set and go...

Noise: None that I can attribute it to.

I agree, it just works once its setup. Heck no need to turn it on or off. Its just plugged in 24/7 (phone charger).

The noise was definitely better for my ribbon and horn setup. The hiss was reduced compared to the DCX. Yeah, gain structure discussion but I do not like using pro amps with gain controls all the time. With my setup and consumer amps that look cool, the MiniDSP is a better solution.

[Paul Spencer]

Rudolf/Dave,

Have you guys used digital input to DCX with no problems?

[Saurav]

FWIW, I have 3 MiniDSPs and Im ordering a 4th (balanced unit). Im getting rid of my DCXs.

Heh. That's good to know. And it's good to hear 1st hand experience from someone who has high-sensitivity tweeters, and has tried both products.

So what products and plugins are you using? Digital input, or only analog? Volume control? Case / enclosure?

[Paul Spencer]

FWIW, I have no noise problem with DCX and my tweeters are 108.5 db 1w1m

[Davey]

Rudolf/Dave,

Have you guys used digital input to DCX with no problems?

I've used mine for nearly seven years and have never used anything BUT the digital input.

Dave.

[Paul Spencer]

Dave,

AES or SPDIF?

I think digital input is the ideal, but more difficult to realise, especially in an all active HT system. I don't know of a way to get 5.1 digital inputs, but then doing the volume control and sorting out preamps gets interesting. It's probably not something I'll consider for some time because in our little test we found the DACs on both DCX and MiniDSP were pretty good. We had a hard time picking a difference between that and a loop cable. Therefore, I focus my attention elsewhere for now. If I could have my ideal though, and perhaps one day I will, I'd have only one digital conversion in the whole system.

[Davey]

Paul,

S/PDIF 90% of the time.

BTW, you didn't answer my question above about the clipping indicator behavior you noticed. Maybe we can zero in on your misunderstanding of the DCX digital input indications if you give me a hint on that?

Cheers,

Dave.

[Paul Spencer]

Dave,

I only tried it briefly, the input clip lights were running hot, I don't recall what the outputs were doing. I didn't wait long enough to notice.

Where is this info about the inputs coming from? By that I mean how have you determined that the clip lights can get it wrong with a digital input? I don't plan on running digital inputs right now because I would need to make other changes in the system to make it work. However, I'm curious to see if you are right and also if it can work with my Blu-ray.

One of the other guys at our active crossover comparison also had the same problem when running SPDIF inputs.

Steve, I hope you'll excuse our little diversion. We are stretching the topic a bit.

[Rudolf]

Rudolf/Dave,
Have you guys used digital input to DCX with no problems?

Unbalanced SPDIF only, from a Yamaha S550 DVD player and the soundcard of my Dell notebook. No problems ever.
I tried the analog input with low (hifi) voltage and did not find it any fun.

I have a test CD with calibration sinus tones of 0, -10, -20, -30 and -40 dB levels. At -40 dB one green input LED is on, at -30 dB still one, at -20 dB two, at -10 dB three and at 0 dB all seven LEDs. It is technically impossible to have more than 0 dB at the input IMO.

[Davey]

Paul,

The info is coming right from my test bench and oscilloscope. I investigated this clipping "behavior" many years ago when I first started using the DCX.

This subject has been discussed extensively in the Yahoo DCX forum and also in the very long DCX2496 thread on DIYaudio.com. If you search that thread you'll notice I (and others) have made multiple postings regarding this.

Cheers,

Dave.

[Paul Spencer]

Thanks Dave, I'll have a look at it.

[Davey]

Check post #107 in 2003 from the DIYaudio.com thread.

Dave.