DEQX

charbug

Member
2014-07-28 2:24 am
First off I want to thank everyone ahead of time for their time. I'm no audio or electrical engineer. I'm just a guy that wants to sit down after working the day job and then working on the farm and relax and enjoy some music.

I have dappled over the years and played around with various gear. Recently I liquidated alot of items to just settle on something that I feel I will like. I do enjoy the Dynamics of horns and just bought new two way Jubilee speakers and ordered radian PB950 drivers with beryllium diaphragms.

I'm older so I do have a nice turntable and enjoy vinyl. I also have a DAC2 from benchmark and have about 1tb of music on a hardrive. My other components are a tavish design phono preamp, the dude tube preamp, and I plan to use a citation II on the horns and a classe DR-8 on the bass bins.

So to be honest the active crossover and EQ of all of this will be new to me. I wanted to stay all analogue but looks like if I want everything dialed in right I have to go digital on the front end. This will allow me to crossover around 500hz, EQ, and get the time alignment of everything right. I want to learn more about all of this but between 60 hrs a week and also having cattle, I do not have time to research and learn more. So after some brief reading the DEQX HDP-4 looks like it is the best product on the markets for what I need to do. It does hurt my feeling knowing I will take my vinyl concert it to digital and then back to analogue but I see no way around this.

So is the DEQX the best product for what I'm trying to do? Also is the hardware in this unit some of the best on the market? Obviously I want quality A/D and D/A converters... I can find very little info on what hardware is in their units...
 
Benchmark DAC-2 would not be of much use if using DSP crossovers with your system. You would need 4 DAC channels, one for each driver.

You would also need an equally good ADC to digitize your analog phono preamp output.

If you want top quality, it can't be done for the price of the DEQX, IMHO.

However, it may be best thing on the market for what you have in mind to do.
 
I have a DEQX and while I like some of its features like a nice implemented linear phase crossover it is not a very flexible unit.

DEQX software relies on good measurements. You can not manually set delay times of individual channels, well actually you can but only is completely useless 1.3mS steps. You also can't eq different outputs independently, there is only an overall eq.

In order to get a good loudspeaker freq response correction and timing correction, you are completely dependant on the software automation process. While this can lead to very good results it also can lead to disappointment. There is a pretty steep learning curve in learning to predict the outcome of the automated calculation. That can be a real challenge. The guys at DEQX are aware of this but instead of making it more user-friendly they started to offer pretty expensive online help for it. This is o.k. if you have a system that you only build once and then forget about it. It is not very flexible if you like to experiment with different or different configurations. I have been looking at this one Analog-Precision – Home of the Ultimate-Preamplifier !. It offers more flexibility, and probably better hardware as well. The only problem with this solution is that it is a one man firm that is only in it's startup phase so you won't know if there is any support for it in the future.
 
I both worked with Minidsp, groundsound, hypex, behringer and deqx.
Deqx is definitely the most annoying one, since you cant really do what you want - when you finaly want to adjust freely.
Deqx also sounded kinda dull to me when it started doing it's auto-thing. When we the turned all of tha auto off, then it sounded fine again, but then I see no reason to pay tons of money to get all it's features to begin with. Looked through the opening at the side of the case..... it's exactly the same DSP as older behringer use.
I belive the all Deqx have the same limitations - only worked with the biggest one - cant remember the model.
After that we played around with the minidsp - believe it was the C-DSP 8-12 car audio version. But I think it has to be the version 2.0 to have fixed the noise issue.
It's rather cheap, but we found no real issues even paired with SS berrylium tweeters and top notch drivers from SB, Eton, Flexunit... you name it. Lots of clarity and control.
I personaly own a Groundsound DCN28 - which I'm very happy with, since noise and control is really at an awesome level with this one. But it's sadly discontinued.
My advice would be to use a straight up unit like the minidsp and squeeze in a little practice with a microphone , so that you get familiarized with how simple it actually can be to measure your speakers and make the best adjustments in the DSP to get really good sound. This will really pay of in comparison with using auto-products that simply try to do all the work - but less effective.
Please list what you currently have in your inventory - drivers, amplifiers soundcards.... Then we'll help with the rest :)
 
Thanks digitalthor.

I own a DDRC-88D. It is a great idea/concept as it has SPDIF in and out so all processing are done in the digital domain and no need to do any A/D conversion and I can use my higher quality DAC for D/A conversion. The sound quality will be least compromised that way.

However, I have issues with the unit not consistently syncing with my SPDIF sources. I believe it is issue with the unit as I tried different sources and they all have issue with signal dropout or not syncing with the source at all. I sent back my unit to minidsp and hopefully they can fix it.

meanwhile when I am waiting for minidsp repair, I borrowed a minidsp 2x4HD. the unit is more robust than the much more expensive DDRC-88D. No issue with syncing or signal dropout. in fact, functionally it works very seamlessly. However, the issue is that the sound quality takes a bit hit and would be wasting the rest of the system to put in such a SQ bottleneck.

I am hoping the DDRC-88D can be fixed and not a design issue.

I was considering the DEQX but with the comments here, I am going to drop that idea.
 

billshurv

Member
Paid Member
2014-03-01 11:53 pm
I've not noticed huge SQ issues with my 4x10HD, but the thing I like about it as that all the channels are available as i2s on header pins inside, so as and when I get the urge I can upgrade the DACs.


I would be interested to know the areas in which you think the quality is lacking with the 2x4HD
 
Sjef,

regarding the inflexibility of EQ and delay setting, is that the case for all the DEQX models?

Yes, this is for all DEQX models since they all run on the same software.

What strikes me is that after all those years there are not many available options out there when you want a high quality dsp crossover with good volume control so it can function as a preamp. Minidsp is a mixed bag in their offerings. Most are cheapie and cheesy sounding. The ones that do sound a little bit better have only two-way crossover options. I have tried a 2x10HD but it does not sound as good as my DEQX unit, it does offer more flexibilty though. I have been on the lookout for years to find a good replacement for my DEQX but have not found it yet. The Analog Precision comes closest to what I have seen so far but like I said, it is still a one man startup which scares me a little to be honoust. It's a lot of money when you have no decent guarantee. I have been very close to ordering one. (still in doubt a little)
 
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Hi Sjef,

I have the same thoughts. That's the reason I went with the DDRC-88D, it has SPDIF in/out and no AD/DA involved in the process. Now, we are still under the assumption that the DSP algorithm is properly implemented. Looking at the support from Analog Devices, the chip used by minidsp. Analog Devices already have library support for all the LP/HP/EQ functions. My guess is that minidsp is just using the AD provided routines and provide a better user friendly interface to it.

Anyway, I don't think it is a large enough market for many company to spend a lot of R&D on it.

The Analog Precision does look quite good but as you said, it is a lot of money for a not widely reviewed product.

My main use case is for active DSP crossover. and it is hard to find a very good sound quality and functionality solution. It would be nice to have the following:

- processing in digital domain - ie. SPDIF/AES/I2S input / output
- easy to use UI for per driver adjustment
- multi channel good quality DAC as an option
- analog volume control. level control per channel but also have a global volume control.

I thought I had most of the above solved with the minidsp 88D. It only have digital volume control, and I use high quality DAC units to drive the output goes straight to power amps.

Unfortunately, I had issues with it, input sync is flakey and I get random sound cutoff. minidsp claims that they have never seen it and hopefully they have fix it in mine.

Given all that, it does sound very good.
 

billshurv

Member
Paid Member
2014-03-01 11:53 pm
Interesting to learn that the 4x10HD has I2S. Browsing it further there are also boards available in kit form. Will be handy for future DIY projects!


The miniShark is another DIY option. I believe that is the same core processor in your DDRC and a jump up from the 4x10 or nanodigi. I was time/funds limited when I made my choice so the 4x10HD was right for me. Whilst nothing is perfect it fitted my use cases at the time. If you run a media PC then Ultimate Equaliser is also worth a look. No good for me as a key requirement is I can listen to music without needing a PC running.
 
The miniShark is another DIY option. I believe that is the same core processor in your DDRC and a jump up from the 4x10 or nanodigi. I was time/funds limited when I made my choice so the 4x10HD was right for me. Whilst nothing is perfect it fitted my use cases at the time. If you run a media PC then Ultimate Equaliser is also worth a look. No good for me as a key requirement is I can listen to music without needing a PC running.

I will have to look into the miniSHARC if my 88D doesn't work out. Regardless it can be a fun project. With I2S in/out I can hookup a good DDC source as well as have custom multichannel DAC stage. I don't really have the chops for the software but that part is already solved.
 
I have received my 88D back and it is working better than before.

minidsp says they have replaced all internal boards. which mean it is essentially a new unit.

Previously, it will have flakey sync with the source, any source. sometimes it takes a few seconds before sound comes out, and intermitently it will stop syncing and i get sound dropout at random times.

now the repaired unit doesn't do that.

however, it is still not syncing with one of my source, a Auralic Aries Femto streamer. it works with all other DACs, except the 88D. I wonder if it is a software issue.
 
Sounds like a driver issue. Driverless devices are in reality not driverless but rely on the drivers already present in the operating system. I have had a same kind of issue with a Motu Ultralite AVB soundcard. It works with it's own drivers but can also work driverless with limited functionality. That works stable under windows and OSX but gets out of sync after a couple of minutes under linux on a raspberry pi. The aries also runs on a linux distro as far as I know. That could be the problem
 
I don't know how the 88D decode SPDIF. normal DAC will use a receiver/decoder chip to convert SPIDF to I2S to feed a DAC chip. but the 88D is feeding a Analog Device DSP so it may well be doing SPDIF decoding via software.

If I have time I will try to look at the SPDIF stream from the Aries to see if there are any difference in the data sent. In the mean time, I am just gonna use my other source to feed the 88D. In this case, I don't really see if there are any benefit with different source as long as the bits are decoded correctly. It will be reprocessed in a DSP anyway so things like jitter should be irrelevant.
 
Thanks digitalthor.

I own a DDRC-88D. It is a great idea/concept as it has SPDIF in and out so all processing are done in the digital domain and no need to do any A/D conversion and I can use my higher quality DAC for D/A conversion. The sound quality will be least compromised that way.

However, I have issues with the unit not consistently syncing with my SPDIF sources. I believe it is issue with the unit as I tried different sources and they all have issue with signal dropout or not syncing with the source at all. I sent back my unit to minidsp and hopefully they can fix it.

meanwhile when I am waiting for minidsp repair, I borrowed a minidsp 2x4HD. the unit is more robust than the much more expensive DDRC-88D. No issue with syncing or signal dropout. in fact, functionally it works very seamlessly. However, the issue is that the sound quality takes a bit hit and would be wasting the rest of the system to put in such a SQ bottleneck.

I am hoping the DDRC-88D can be fixed and not a design issue.

I was considering the DEQX but with the comments here, I am going to drop that idea.

I have not tried the DDRC-88D. But I hope they fix it. Or else I can recomend the mobile version for cars - with the higher signal output, it helps a bit with keeping the SN in check.
All the fiddleling with DAC's, I2s and worrying about AD/DA conversions.... crossed my mind but did not keep me up at night.
I would use far more energy on good measurements and properly build speakers with well thought out choices, when it comes to drivers :xmasman:
 
Just wanted to throw my experience in the hat with an DEQX HDP Express II..

So far I'm very happy with my purchase. Believe the hype, this thing really took my system to a new level and
I don't think I'll ever go back to passive crossovers unless I have to.

Alot of the interface IS automated, as in you just set the parameters and it does the calculations. I am a forever tweaker and adjuster, but I actually like the interface.

To me its quite intuitive once you get the hang of it. But like many good interfaces its
simple (as in automated) yet the possibilities go extremely deep if you understand what you're doing. I dont think it would be possible to do on a passive knob adjusting passive crossover what you can do on the DEQX.

A couple of things that the DEQX does

1) Group delay alignment
2) Step Response
3) Perfectly matched crossovers
4) Phase/Impulse correction

A case study is what I've done with my Earl Geddes Nathans. Just even as a 2 way, with the DEQX they sound wayyyyy better than the passive crossover they came with. Suddenly the 10" woofer is giving me more than enough bass and I was able to set the crossover 500hz LOWER with a shallow 48db slope. This gives an exeptionally natural sounding transition between bass and the treble waveguide.

I'm also powering the 4 speakers with a 6 channel Edge GAV-6 amp I bought used which just has 6 Icepower 500asp's inside. And wow... You really do need alot of power because the shaping is so extreme that the cut goes as low as 30db. Now at the levels I'm listening to Im not worried about damaging the speakers but it remains to be seen long term if it'll be ok.

What I can say is that using sensitive speakers with the DEQX like the B&C DE250 1" CD works amazing with the DEQX because they have alot room for shaping due to high sensitivity. I'll post below the crosssover I'm using, and honestly even I was surprised how good they sound now, like different speakers. Im building a mid horn using a DE750tn to go active 3way so I'll report how it sounds once that materializes.

But if you were wondering if its worth it, so far I'd say yes! But I can only speak for the setup I have now which is quite sensitive speakers and aof lot power to amp them with. Another note is once I took away the noise filter with the passive crossover in the speakers now I'm dealing with alot of hiss from the CD's so I'm trying to figure out how to deal with that. Just use a resistor in series??

So anyways without hyping too much..in my journey as an audiophile I've come to realize
that at least in my own case alot of what I've been chasing with high quality exotic amps
and DACs can really be solved in the digital domain with speaker correction with frequency response, crossover and phase/time alignment.
 

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