DSP controlled 3 way

[SashaV]

Hello guys,

I would like to ask for some suggestions and help to start a project for 3-way DSP controlled speakers using DEQX.
A few words on what I am after. About the only commercial speakers that I liked to some extent were active ATCs and most recently the new DSP controlled PMC IB2.
Both had some issues though.
Would I be better off with an attempt activate an existing commercial passive speaker, let’s say passive PMC IB2, or start from scratch?
I do not posses lots of experience and knowledge, so if a new design has significantly higher potential for great sound that would surpass those commercial offerings, I would probably commission someone with proven record and lots of experience to design enclosure, possibly build it as well.
Considering my preferences, can you make suggestion on a set of drivers that I should consider? Size wise I am thinking 70 liters box. I guess I could start with ATC sm75-150s as mid, what would complement them well? Or is there something else that I should consider for midrange? As far as ATC mid dome goes, it sounds almost perfect in ATC implementations, but there is a kind of hardness to the sound, I do not know if it is due to the resonance that some mentioned here around 4.5kHz that is still audible because of too high crossover point chosen by ATC (3.5kHz) or it is simply its trait? What else is there that can measure up? Is Audio Technology good, would their polypropylene cones be too dark and not so lively?

[whgeiger]

.... is a military term, that applies here as well.

Incorporating a DSP Crossover into your design strategy provides wide latitude in driver selection and the flexibility required to arrive at an optimal design given the drivers you eventually select. Give consideration to the following when proceeding with driver selection and the rest of system design:

1) Are subwoofers to be used?
This will affect the LF driver selection for the satellites.

2) Will ATC sell you the drivers you want?
Here I would suggest you expand your horizons to include other manufacturers’ products.

3) Set a project budget and proportion it by frequency channel.
You have three decades to cover, make sure adequate funds are available for each.

4) Maintain control of the design. You can do it. Just let others and your ears critique what you come up with. Do a lot of reading and auditing when selecting drivers. Gain an understanding of driver parameters, so you can boil-down the candidate list to just a few to listen to.

5) Design is an iterative process, so traversing circles should be anticipated.

The issues addressed here, do not represent a comprehensive list of those you will encounter during the course of your project, but they should serve as a determinant for what will certainly follow.

Regards and Good Luck,

WHG

[ShinOBIWAN]

Originally Posted by SashaV

As far as ATC mid dome goes, it sounds almost perfect in ATC implementations, but there is a kind of hardness to the sound, I do not know if it is due to the resonance that some mentioned here around 4.5kHz that is still audible because of too high crossover point chosen by ATC (3.5kHz) or it is simply its trait? What else is there that can measure up? Is Audio Technology good, would their polypropylene cones be too dark and not so lively?

The ATC SM75-150S is a very expensive proposition now, its a whisker over £300 each here in the UK.

A comparable Audio Technology driver would be the excellent C-Quenze 15 H 52 12 06 SDKM which is a dedicated midrange or alternatively if you don't require a 91dB sensitivity then the C-Quenze 15 H 52 06 13 SDKAM is 89dB and has a flatter response. Price wise the AT drivers are cheaper than the ATC but not by a huge amount(£220each UK).

In terms of comparisons they're both strong drivers when used correctly but I prefer the AT's for their more refined character and very bandwidth performance. My main issues with the ATC are its limited bandwidth and pretty ragged response which pigeon holes it into pretty much one crossover configuration - approx 500hz to 3Khz with fairly steep filters such as 24dB/oct or greater. The AT on the other hand is nicely flat across its usable range and can extend happily down to 150hz and all the way up to 5Khz and beyond. This flat and extended pass band is great for low order filters and general crossover design flexibility. As for the dark quality sometimes associated with poly cones, the AT's have none of that I've heard. I do think the debate over the contribution to colouration from cone material is often overstated. I've used many including magnesium, poly, paper, ceramic, cloth, aluminium and so on. My observation is that good drivers have more in common than not regardless of cone material.

What the ATC is capable of is hard to ignore and the AT aren't quite as dynamic sounding but as you've already pointed out this dynamic ability comes about as a certain forward nature that can be tiring on long listening sessions.

[Digi]

WHG has some good suggestions, I would like to add my DSP experience.

The DEQX is overpriced and limited compared to what you can accomplish with a dedicated PC. The DEQX is basically a botique version of a pro audio active XO. Using Audiolense or Accourate you can get a very good sounding system in 15 minutes, maybe 90% of it's ability. Audio Lense, which is what I use, does not look at DSP XO the same way that the DEQX does. The DEQX is a 1 through 8 pole DSP, max 48 db/oct, Audiolense has an almost infinite amount of slopes, and is not limited to classic filter design.

Subjectively, using a PCXO with Audiolense, the sound is like a good pair of headphones. Imaging is unreal! Flat frequency and phase response, without any pre-ringing, pretty much the holy grail of XO and frequency correction.

I have not used the newest version of Accourate, but it similar except the fact that it uses traditional crossover slopes, LR, butterworth, etc.

As far as the ATC drivers go, I think that Solen still sells them. I would build a system from scratch, and the ATC mid would be a good place to start. I wouldn't bother with the Audio Technology drivers, all of the measurements that I've seen of them are good, but not great, and certainly far below the price tag. I would look at the Acoustic Elegance drivers, they seem to be the best of the best. I have AE 15s and 10s and they are beasts...

I could give you details of a fool proof PC setup. I've been running my PC system for about 6 years now, and it's dialed in. I know for many Hi-Fi nuts making a PC your source/XO might seem subpar as far as audio quality, but it is the cutting edge. Pro Audio sound cards are top notch and I would stack them up against anything the so called "Hi-Fi industry" has to offer.

Rob

[whgeiger]

Originally Posted by Digi

I could give you details of a fool proof PC setup. I've been running my PC system for about 6 years now, and it's dialed in. I know for many Hi-Fi nuts making a PC your source/XO might seem subpar as far as audio quality, but it is the cutting edge. Pro Audio sound cards are top notch and I would stack them up against anything the so called "Hi-Fi industry" has to offer.
Rob

Digi Rob,
I am interested in what you done here as I need to build several new PCs for PA work. I want to add a Karaoke front end to them as well.
I build all my PCs from scratch using motherboards, power supplies and cases from SuperMicro. What sound cards are you using? Software?
Regards,
WHG

[SashaV]

Shin,

If I could not get ATC SM75-150S, would there be any performance penalties with non S version?
At this time only standard version is available from Solen.

[Digi]

Originally Posted by whgeiger

Digi Rob,
I am interested in what you done here as I need to build several new PCs for PA work. I want to add a Karaoke front end to them as well.
I build all my PCs from scratch using motherboards, power supplies and cases from SuperMicro. What sound cards are you using? Software?
Regards,
WHG

Supermicro is a good choice, I've used many Supermicro and Tyan MBs in the past. My HTPC that does all of my audio processing uses a Gigabyte GA-MA790XT, with an AMD X4 @ 2.8 GHz and 8 GB of RAM. I use an Echo Audiofire8 as my soundcard. It's a firewire based soundcard with a solid all aluminum chassis. I have a few other sound cards that I've tried over the years and the Echo is my favorite and most reliable.

I use Plogue Bidule as my VST host, I started with Console but it wasn't very stable, plus Bidule has more useful features than Console. Within the VST host I use Voxengo Pristine Space. I use Voxengo products for pro audio applications and gave it a try, it's perfect for XO applications. There are some other VST convolution plugins out there that are free but I really like the interface of Pristine Space. And Foobar seals the deal, by far the best audio player made, and it's free.

Here's the audio chain: Foobar>Bidule>Pristine Space>Echo Audiofire>Preamp>Amps I also run my Cable DVR into my stereo for watching TV. The cool thing about feeding the DVR into the PC is I can throw a compressor in the VST host and it will stop the obnoxiously loud commercials from driving me up a wall.

Rob

[ShinOBIWAN]

Originally Posted by SashaV

Shin,

If I could not get ATC SM75-150S, would there be any performance penalties with non S version?
At this time only standard version is available from Solen.

I can't really recommend the standard version. I tried both in the same design and whilst they share the same traits it is audibly inferior to the super version.

Here's a couple of shots to shot just how much larger the motor is on the super.

[ShinOBIWAN]

Originally Posted by Digi

WHG has some good suggestions, I would like to add my DSP experience.

The DEQX is overpriced and limited compared to what you can accomplish with a dedicated PC. The DEQX is basically a botique version of a pro audio active XO. Using Audiolense or Accourate you can get a very good sounding system in 15 minutes, maybe 90% of it's ability. Audio Lense, which is what I use, does not look at DSP XO the same way that the DEQX does. The DEQX is a 1 through 8 pole DSP, max 48 db/oct, Audiolense has an almost infinite amount of slopes, and is not limited to classic filter design.

I'm not sure where your getting you information on the DEQX from.

The DEQX filters are based on taps (approx 4096 correction points per channel) just like the filters generated by Acourate and Audiolense. The filter slopes are variable from 12dB upto 300dB/oct linear phase.

I'm also not sure how the DEQX can be branded a boutique version of anything whether it be from the pro audio arena or the home one. It stands on its own because no other single standalone box handles the same set of problems like the DEQX does. You can get boxes that do portions of what the DEQX does but the feature sets aren't as complete.

As far as the DEQX vs. PC comparison goes. The PC has the edge in sound quality but only with reasonably high end partnering equipment and its not without complications that the DEQX simply doesn't suffer from. When I used Acourate for my filters it took considerable effort to get a useful processing platform for both audio and video application and even then it wasn't perfect and required a set of IIR filters for AV and FIR filters for audio only. In comparison I have no issues with the DEQX, the FIR filters have low delay so I can use it with AV applications and its pretty much set and forget.
So its for me the switch from PC to DEQX has been a trade of a small amount of sound quality for ease of use.
If your comparing costs the PC setup I had at the peak cost a good amount more than the DEQX too but I do concede that the PC route can be very economical yet still sound fantastic.

BTW I still think if your after the ultimate quality the PC route can offer that but its neither cheap nor is it a set and forget solution when it comes to processing audio and video.

[whgeiger]

Originally Posted by ShinOBIWAN

I can't really recommend the standard version. I tried both in the same design and whilst they share the same traits it is audibly inferior to the super version.

Here's a couple of shots to shot just how much larger the motor is on the super.

Have a look at this.
ORCA Design & Manufacturing
Regards,
WHG