DSP Xover project (part 2)

Compare with DEQX

Hiya,

Congratulations on this DSP crossover, I just found this thread and as long time user of DEQX I am excited by the prospect of matching DEQX functionality and sound quality but at an affordable price.
I was just about to upgrade my DEQX digital in / digital out board to the latest spec so this thread is great find!

Subject to questions below, I would like one board with the analogue volume chip, the extra $40 is worth it to allow A/B comparisons against digital volume done externally in seperate DAC's Vs your on board DAC.
I use 3 external stereo DAC's ( TP Buffalo 2) at the moment.

Functionality:
(1) DEQX Vs your board? ie Does your board do individual driver measurement / correction as well as individual speaker measurement.
(2) Linear Phase crossover up to 300dB / octave slopes?
(3) Also a big point here, the DEQX runs out of processor power (even with it's twin Shark DSP's on board) when asked to do 96KHz measurement and steep linear phase crossover slopes below 400Hz, can your board cope with this?
I need 60dB / octave linear phase slopes at 70Hz and 250Hz to allow a three way crossover with BMR's above 250Hz, cones down to 70Hz and then subs ( 3 subs) below 70Hz.
(4) Room measure / correction with real time correction ie adjust while listening to music.

Last minor questions, dimensions of your board, power & heatsink requirements? Everything ( including power amps) in my system is run from LiPo batteries.

Sorry if I have asked questions that have been asked before but I think a direct " Like for Like " comparison against DEQX as the long term market leader is something that will interest lots of DIY dudes & divas!

Thanks in advance and all the very best with your project.
Derek.
 
Filters

PS
DSP cloned analogue filters such as Linkwitz / Butterworth etc are of zero interest to me.
Only Linear Phase filters, between "48dB / octave and 96dB / octave is the best zone to my ears.

Lastly, if you have time(!) I would be interested to hear your views on IIR Vs FIR?

Thanks
Derek.
 
Hi Nick,

I'm interested in the board with the analogue level control.

Best regards,
Indemini

Hi Nick,

I'm also interested in the board with analogue volume control.

Cheers
Sven

Thanks Indemini and Sven for your input, that's good for my statistics. So far it seems that there would be about 80% interest for the board + analogue volume chip.

Hiya,

Congratulations on this DSP crossover, I just found this thread and as long time user of DEQX I am excited by the prospect of matching DEQX functionality and sound quality but at an affordable price.
I was just about to upgrade my DEQX digital in / digital out board to the latest spec so this thread is great find!

Subject to questions below, I would like one board with the analogue volume chip, the extra $40 is worth it to allow A/B comparisons against digital volume done externally in seperate DAC's Vs your on board DAC.
I use 3 external stereo DAC's ( TP Buffalo 2) at the moment.

Functionality:
(1) DEQX Vs your board? ie Does your board do individual driver measurement / correction as well as individual speaker measurement.
(2) Linear Phase crossover up to 300dB / octave slopes?
(3) Also a big point here, the DEQX runs out of processor power (even with it's twin Shark DSP's on board) when asked to do 96KHz measurement and steep linear phase crossover slopes below 400Hz, can your board cope with this?
I need 60dB / octave linear phase slopes at 70Hz and 250Hz to allow a three way crossover with BMR's above 250Hz, cones down to 70Hz and then subs ( 3 subs) below 70Hz.
(4) Room measure / correction with real time correction ie adjust while listening to music.

Last minor questions, dimensions of your board, power & heatsink requirements? Everything ( including power amps) in my system is run from LiPo batteries.

Sorry if I have asked questions that have been asked before but I think a direct " Like for Like " comparison against DEQX as the long term market leader is something that will interest lots of DIY dudes & divas!

Thanks in advance and all the very best with your project.
Derek.

Hi Derek, thanks for your interest.

I would like first to stress out that the DEQX and my project are based on completely different philosophies.

Correct me if I'm wrong: the DEQX is a boxed finished product. My board is just the start of the customer's own sound system project, and the final product is going to be what the user makes out of it.

What this means is that I want to give as much freedom as possible to the user so that he can build the final product that he has in mind. As a result there's space for various hardware expansions and tuning - and similarly the software itself will offer a lot of freedom, looking like a toolbox where the user picks what he thinks suits best to his system.

One thing that my board doesn't do at all, that's measurement. The board I'm preparing is a processor, i.e. a board performing the processing. You can measure your system with one of the many applications available then, if you wish, import the graphs in my software in order to visualize the changes operated by the processing.

Another thing that my board doesn't do, that's automatic tuning. The type and amount of processing is selected by the user. Again, there are many strategies available from various projects here and there (among them PORC presented in this forum), so you can run one of these and import the results into the processor. The idea is that one strategy might not fit all systems - and my board wants to allow you trying various approaches to processing.

Finally, I made my best to keep the cost of the board low without making irreversible compromises on sound. The result is a product that's expected to be DIY friendly in terms of fun, functionality and ... money-wise.

Given the differences highlighted above, in terms of approach, use and cost, I'm afraid it's not possible to compare my project with the DEQX.

PS
DSP cloned analogue filters such as Linkwitz / Butterworth etc are of zero interest to me.
Only Linear Phase filters, between "48dB / octave and 96dB / octave is the best zone to my ears.

Lastly, if you have time(!) I would be interested to hear your views on IIR Vs FIR?

Again, I don't want to make a statement on the 'best' filter for audio applications. I actually stopped believing in a 'one-fits-all' strategy, especially for the technically enclined DIY aficionado as opposed to the customer of a ready-to-use product.

The simple filters that you mention - Linkwitz and Butterworth - are certainly not optimal. However, they are well known (including their limits), they've been used for a long time in systems that sound great, and also they are relatively easy to understand and manipulate. I'd say there's nothing wrong with using such a filter in your system - so these filters are going to be available, along with more stuff! Stay tuned! :)
 
Different goals from DEQX

Hi ChaparK,
Thanks for your fast response and I now understand your goals now and I can see the differences between DEQX and your board.

I will follow with interest the way your project develops it has a lot of great features and I wish you all the very best
Cheers
Derek.
 
And the programming is almost done ? :worship:

:)

Actually yes we can say so. ;)
Micro-controller code is completed. That includes all SPI peripherals management, LCD, IR sensor, USB communication etc.
DSP code is nearly done.
Most of the remaining work is on the control application. It's of course already communicating with the board and I have big chunks in place under Windows and Linux.
 
I must say. Isn't this a vast programming task? A couple of platforms and a gui as I understand. Are You doing all by Yourself? (I'm in the programming business myself, database oriented applications.) I'm impressed even if You wouldn't succeed.
Best wishes.

Yes that's a lot of work. There are other things coming on top such as schematics, PCB design and filters design. It's going to be fine :)

:D Looking forward the presentation ;)

maybe a sneak preview of the board design:)

So I'm right now looking at quotes from the PCBA manufacturer. Lead time is 40 days and I'm requesting first 1 board to make sure there's no issue with assembly (there's over 400 components on each board). I'll post pictures of the first board.

would it possible to order a board without the rca connectors? i don't need them and desoldering is alway a risk to damage the board. i only need the digital inputs and the usb connector.

That should be doable, to be confirmed.

Do the digital inputs and outputs have transformer isolation?

All outputs are isolated (5 transformers). Input is not isolated - I made here the assumption that the line is isolated on the source side, which is usually the case in my experience.