Bass Management System Development

**brucek** · **03-02-07, 12:01 PM**

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Anyone else still interested?

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I am! I think it's on the right track for everyone

Well, maybe not everyone.

I don't like to be negative about this, because I appreciate the effort that's been put into the proposal. I wonder how popular a device would be that required the addition of another companies hardware to operate?

The specs don't appear to be very good on the FCA202. Here's a few observations.

1. The analog output is consumer level of +2dBV. This voltage is unsuitable for driving many PRO amps.

2. The analog input has no balanced capabilities. Not acceptable to those using processors with balanced connections.

3. They've weighted the S/N ratio and defined it at 1KHz. Typical trick to hide a poor noise figure.

4. The harmonic distortion is defined at nominal levels and not max input. And why not total harmonic distortion so we know that more than the first order harmonics are considered.

5. It has no gain control.

6. What are the possibilities of Behringer discontinuing this device , rendering the proposed equalizer unusable.

Anyway, I've just read through this whole thread and wonder if I'm the only one who feels the original intent of this project has left the tracks somewhat?

The basic premise was that we liked the BFD and all its features, but wanted to add on RCA connectors, provide better specs (like a 2496), extend the filter control down to 10Hz, maybe add a shelf filter, and clean up a few problems such as turn on thump and ground loop hum. Not a big deal for Behringer that already had devices that possessed these added goodies, and since the parametric feature was basically a cursory function in a feedback destroyer, we simply wanted everything removed except the parametrics with the addition of a few extras. Well within the purview of Behringer.

Again, for myself, the features that the BFD already offered weren't on the negotiating table. These were a given. That includes analog unbalanced and balanced XLR connections on both input and output, selectable input/output control between pro and consumer levels, a fully functional front panel with VU meters and filter indicators, etc, etc.... well, you get the idea, it's all in the list. I'm personally not interested in adding extra boxes on to get these basic features that I already enjoy, nor do I want to be adding firewire interface cards to my old REW computer. I have to be honest, and with respect, I never really warmed up to firewire, and when Apple dropped their support of firewire to ipods etc, well I thought the handwriting was on the wall. The device would have to support USB. I suspect that's somewhat of a global sentiment at this site, although I may be wrong.

Anyway, I know I'm only representing one opinion, but I'm not really interested in convincing anyone about the basic features I require in a parametric equalizer. I already enjoy about 95% of everything I need in a cheap BFD. The project appears to have moved away from the basic needs to more of an attempt to showcase firewire than in providing what the market wants. That's fine, and I understand the business requirement, but I don't think the proposals so far would be a seller. That may well be evidenced in the lack of enthusiasm shown so far in this thread, with very few participants in relation to the numbers who voted in the BFD poll.

I'm no doubt wrong in my assessment of this device, and it would be the greatest thing since sliced bread. So feel free to ignore my thoughts....

brucek

**Otto** · **03-02-07, 12:18 PM**

Good points, brucek. I guess I could say I'm torn about it. On the one hand, I'm eager to have a better solution (10Hz, remote control, whatever turns you on...). On the other hand, we may be headed down a more complicated path.

And I agree that the current basics of the BFD should remain -- why take a step back? I also agree that we get 95% of what we need for well under $100 on eBay.

Thanks for the comments.

**Sonnie** · **03-02-07, 01:06 PM**

I just needed someone to wake me up... thanks brucek!

We need to get back to finding someone who can build what we really need.

**Ayreonaut** · **03-02-07, 01:30 PM**

Most of our current bass management signal chains include:

1. Digital Signal Processing (DBM) in the Reciever
2. D/A conversion in the Reciever
3. A/D conversion in the BFD
4. Digital Signal Processing (EQ) in the BFD
5. D/A conversion in the BFD

My receiver (and many others) has a digital optical output. It simply reproduces whatever digital in is selected. If you build a system that includes DBM and digital optical input (and coax, etc.) you eliminate 3/5 of the processing and souces of noise. The chain is then:

1. Digital Signal Processing (DBM and EQ) in the "Unit"
2. D/A conversion in the "Unit"

Shouldn't we insist on digital in?

**brucek** · **03-02-07, 03:28 PM**

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My receiver (and many others) has a digital optical output

The only function of a digital output on a receiver or processor is for digital dubbing using a CD or MD recorder. It's analogous to an analog tape loop, only in digital.

Conventionally, the receiver or processor do all the bass management and processing of the various digital formats (that require licensing) and then output analog to an external amplifier or speakers.

brucek

**Ayreonaut** · **03-02-07, 05:04 PM**

Ah. I guess you would have to have a full-fledged surround processor in the "unit" to construct the sub signal. Too much.

**bvwj** · **03-02-07, 05:11 PM**

Quote:

The specs don't appear to be very good on the FCA202. Here's a few observations.

1. The analog output is consumer level of +2dBV. This voltage is unsuitable for driving many PRO amps.

2. The analog input has no balanced capabilities. Not acceptable to those using processors with balanced connections.

3. They've weighted the S/N ratio and defined it at 1KHz. Typical trick to hide a poor noise figure.

4. The harmonic distortion is defined at nominal levels and not max input. And why not total harmonic distortion so we know that more than the first order harmonics are considered.

This is the input I wanted on the FCA202.

Quote:

6. What are the possibilities of Behringer discontinuing this device , rendering the proposed equalizer unusable.

The intent isn't to build a system around the FCA202. It's just a proposed starting place. The price point of the FCA202 almost enables a system at your price goals. There are several other higher quality (more expensive) FireWire ADC/DAC units. On the FireWire side they interface the same, so it would not be much effort to enable a number of different interface devices.

I envision smaller, much less expensive, single purpose devices (instead of 2x2, 4x4, and 6x6 units). I was just hoping the FCA202 might be a starting point to enable the system without investing immediately in analog I/O development.

Quote:

Anyway, I've just read through this whole thread and wonder if I'm the only one who feels the original intent of this project has left the tracks somewhat?

The basic premise was that we liked the BFD and all its features, but wanted to add on RCA connectors, provide better specs (like a 2496), extend the filter control down to 10Hz, maybe add a shelf filter, and clean up a few problems such as turn on thump and ground loop hum. Not a big deal for Behringer that already had devices that possessed these added goodies, and since the parametric feature was basically a cursory function in a feedback destroyer, we simply wanted everything removed except the parametrics with the addition of a few extras. Well within the purview of Behringer.

Again, for myself, the features that the BFD already offered weren't on the negotiating table. These were a given. That includes analog unbalanced and balanced XLR connections on both input and output, selectable input/output control between pro and consumer levels, a fully functional front panel with VU meters and filter indicators, etc, etc.... well, you get the idea, it's all in the list.

I'm personally not interested in adding extra boxes on to get these basic features that I already enjoy, nor do I want to be adding firewire interface cards to my old REW computer.

I certainly can't demand that you negotiate features with me. I just thought I spotted an opportunity that might fit me better than it fits Beheringer. I'm really not trying to negotiate as much as I'm trying to understand what the critical features are. Clearly some features of existing systems are required and others are not. I have my opinions, but I appreciate yours.

Quote:

I have to be honest, and with respect, I never really warmed up to firewire, and when Apple dropped their support of firewire to ipods etc, well I thought the handwriting was on the wall. The device would have to support USB. I suspect that's somewhat of a global sentiment at this site, although I may be wrong.

Apple dropped FireWire support on iPods, there really isn't any etc. All the new Macs have firewire. It would be much more difficult and expensive to develop this sort of device with USB.

Quote:

Anyway, I know I'm only representing one opinion, but I'm not really interested in convincing anyone about the basic features I require in a parametric equalizer. I already enjoy about 95% of everything I need in a cheap BFD. The project appears to have moved away from the basic needs to more of an attempt to showcase firewire than in providing what the market wants. That's fine, and I understand the business requirement, but I don't think the proposals so far would be a seller. That may well be evidenced in the lack of enthusiasm shown so far in this thread, with very few participants in relation to the numbers who voted in the BFD poll.

I'm no doubt wrong in my assessment of this device, and it would be the greatest thing since sliced bread. So feel free to ignore my thoughts....

There is no way you can be wrong on this. Obviously you understand exactly what you want. I just keep poking you with sticks looking for sore spots any you've been kind enough to tell me how bad it hurts.

I appreciate that you don't dismiss my business requirements. My goal is to showcase FireWire AND provide what the market wants. You're accurate that I understand FireWire better than the market. I'm participating here to learn about the market.

I will continue to appreciate any effort you choose to spend convincing me of the basic features you require in a parametric equalizer. I can't promise a device that delivers your exact feature set, but I am listening.

**ACGREEN** · **03-02-07, 09:56 PM**

I agree that in a perfect world, that audio signals would be fed to the speaker in a digital format with the speaker being amplified with its own DAC. With most receivers converting every signal to digital the signals would only have to be converted once and remain in the noise-free digital domain.

The problem. Speakers would require power. This would be a difficult transition in a set market.

With you device, I think to mush analog-to-digital-to-analog processing is going on. I think that more noise would be introduced then would be saved my the digital runs.

While I would love a subwoofer calibrator for under $200, I don't think Firewire is the answer.

I am trying to think of some applications for firewire...

**Danny** · **03-03-07, 04:01 AM**

I like the idea of digital to the speakers however the supply of power to the device presents a problem that needs to be solved (perhaps a IEC in and also an output IEC connector, that is power going into the device powering it and then going to the sub). I would like the idea of having PC control of the device (maybe like Sabine have done with their GraphiQ range)

**Danny** · **03-03-07, 04:14 AM**

And also maybe you could investigate the idea of making the unit full range compatible and include a graphic EQ. This would increase the viability for pro audio to use it. Currently in many installations there are long 100ft plus analog cable runs from the desk to amps rack. There has been an increased occurrence of digital products as well eg Roland Digital snake.

**Fader** · **03-03-07, 08:44 AM**

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bvwj wrote:

Sonnie,

I appreciate fewer boxes. My concept for the D/A is a mouse sized box that could literally hang of the RCA or XLR connector to the sub amp, not another rack sized piece of equipment.

Can you expand on your concerns about firewire to the sub?

I assume that in this concept, you would need one of these mouse sized D/A at each sub? What would be the add on cost for each additional D/A?

**bvwj** · **03-03-07, 11:44 AM**

My target for a single channel, unbalanced, sub D/A is $40-50, so $50 for each additional sub. Blanced might be a little more. Full range might be a little more. Two channels might be a little more. If I could convice a sub manufacturer to integrate it, a digital-in sub could be less expensive than a similar analog-in sub.

Under 15' (4.5m) power is easy. Standard FireWire cables can carry plenty of power to power all the DACs. No external power supply is needed. In addition, the speakers can be chained from one to the next, so each speaker does not need its own cable run to the equipment rack. For $20 you could extend the run to 30' with a cable powered hub (repeater/splitter). Additional repeaters would be functional, but seem like a poor solution.

For longer distances (up to 100m) you would want FireWire over cat5 or coax. It's more expensive to send power over these cables, but it is possible. Currently I'm thinking it would be most economical to use a wall wart at the end of cat5 and coax runs. Then other DACs within 15' of the long run could again be cable powered.

There is nothing in the DSP archetecture that limits this system to low frequencies. The current concept is sub woofer based because that's where the largest audible gains can be made and because currently that's where the powered speakers are.

The market is beginning to understand digital interconnect. I like this digital snake from I/One. Of course it's FireWire. The entire system can cost less than some multi-channel analog snakes.

Historically audio manufacturers saw FireWire as an interconnect to get audio data into and out of PC's. New extensions to the FireWire standards make it ideal for distributing audio data as well.

**Hank** · **03-04-07, 10:59 AM**

If you can satisfy the basic requirements of this group (current BFD features plus wanted improvements), and have this feature: "included filtering and SPL meter capabilities", I'd be interested and would cancel my plans to buy the Galaxy 150 and accessory software.

**bvwj** · **03-04-07, 08:10 PM**

Don't wait on me if you're ready to do something now. I'm only in the concept / prototype stage. I haven't made any commitments for features or dates.

**ACGREEN** · **03-04-07, 09:32 PM**

Have you thought about audio/video distribution for new homes. This might be better suited for using the application you desire. I am building a new home and the most economical system I can find is Audio Authorities system which runs over Cat5. Maybe your technology would be better suited?

**Hank** · **03-05-07, 12:05 AM**

Barry, thanks for your forthright post. I'm in no hurry and there's a Tuesday deadline for the Galaxy buy, so given that I've got an old RS meter and a recently purchased Behringer ECM8000 microphone and a friend with lots of gear and software and my newTrueRTA and the software on this forum that I plan to learn and use, the ultimate hardware solution, whether your company's or another's can wait.

Also consider ACGREEN's comments. My good friend is having a house built and I am very concerned at what he's paying for wiring his new home for phone, TV, computer, audio, etc. Not that the subcontractor is ripping him off, because I know the number of wires, CAT5, COAX, etc and the associated labor hours involved. Is the alternative a daisy chain single (or almost single) run of firewire??

**mojave** · **03-05-07, 03:01 PM**

Quote:

brucek wrote:

The only function of a digital output on a receiver or processor is for digital dubbing using a CD or MD recorder. It's analogous to an analog tape loop, only in digital.

Conventionally, the receiver or processor do all the bass management and processing of the various digital formats (that require licensing) and then output analog to an external amplifier or speakers.

Quote:

Ayreonaut wrote:

Ah. I guess you would have to have a full-fledged surround processor in the "unit" to construct the sub signal. Too much.

I plan to us a simultaneous analog and digital output with my X-Fi Elite soundcard. It will decode the surround modes and send it out via analog. It will also combine the decoded signal into a stereo pcm digital s/pdif signal. I connect the analog outs directly to my 7 channel amplifier. I will connect the stereo digital coaxial out to a Behringer DCX2496. I will then split the signal to three outputs for my subwoofer, mid-bass module, and Buttkickers. The DCX2496 will handle the crossovers, parametric equalization, phase adjustment, and delay before performing the D/A conversion. I can also control all settings from my computer using Behringer's software.

I received the DCX2496 last week, but I am still waiting on all the cables to arrive before I set everything up. If this works as planned, I will have eliminated a D/A and A/D conversion step.

**ToSi** · **03-07-07, 12:46 PM**

Barry,

I think that to really convince users here to switch to your new system, you'll need to offer features that aren't available in the current commercial products or market to a user base who's needs aren't being met w/ the current offerings..

ACGREEN's suggestion has merit, although I wonder if the cost penalty of using Firewire vs. CAT5 is going to make it possible.

Another option would be to look at the DIY speaker community. Dipoles & active speakers are growing in popularity in the DIY community & there is a lack of affordable digital solutions that can apply the signal corrections necessary to implement these.

Take a look at the active filters page on the Linkwitz Lab site (http://linkwitzlab.com/filters.htm) - I'd be particularly interested in an affordable solution that could apply various combinations of these filters to a signal & output to respective amplifier channels. You could offer modules that handle 2 / 4 / or 6 channels, then rely on the IEE1394 backbone to link additional units together. A/D or D/A can be separate modules. Combined w/ a parametric EQ, these would provide the original features you were hoping to implement (room / bass management) + offer something new that would provide product differentiation.

A separate issue would be to increase the usage of IEE1394 in consumer a/v gear but that's something you'd want to push the equipment manufacturers to do. As an interim solution, you'd want to offer a D/D module that makes it possible to maintain a digital connection to downstream components that don't use firewire. A similar device should be provided to convert SPDIF / Toslink / AES to IEE1394 upstream of your modules.

**bvwj** · **03-08-07, 02:13 PM**

Wiring:

Audio/Video distribution for new (and old) homes is the point.

I believe FireWire has the most compelling advantages for the home AV network. It's not just me, it's also HANA. You'll see many of the major consumer electronics companies are participating in HANA.

I won't explain all the advantages here. TI just authored an article on why 1394 was the best choice for the future home AV and data network.

I think this is coming. My idea is to come to the market ahead of the curve and carve out my piece.

One of the major recent developments in FireWire that enables home AV backbones are the new long haul physical interfaces. FireWire devices can now be implemented to run over standard Cat5 cable up to 100m. The ability to run FireWire over coax is in work and should be available shortly.

The focus of this development has been to enable FireWire AV networks over existing in home Cat5 and coax wiring. The FireWire chips enable both star and daisy chain topologies. Loops are even allowed 1394b enabling redundancy if one segment of the loop breaks.

One wire from any AV component to the next has always been a major feature of FireWire.

**Hank** · **03-08-07, 04:43 PM**

Note ToSi's input - another product possibility for the DIY and CEDIA installation market. If powered speakers are in the future, then doing a product for DIY'ers to enable dipole and active speakers now will get your name in the market and get you ready for the bigger market segment. The new small, effecient class D amps could be deployed at the speakers.

Okay, so what is the most likely product?

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