Why not use External EQ for Speakers and Room Correction

[Hattrick]

There is so many speakers from budget bookshelf to outlandish flamboyant and insanely expensive. So...., why not just build a system which one eliminates crossovers and use external EQ? How about utilizing this for room correction, versus room correction software and or external wall, ceiling, and floor treatments?

 

[Philbo King]

Define "system bypass crossover".

 

[No. 5]

No reason not to, in my opinion. I'm using a professional loudspeaker management system for bass management and room/speaker EQ rather than using what my AVR has. It obviously requires more work and know-how than hitting "go" on Audyssey, Dirac, or whatever auto set-up is available to you, but if you're into that sort of thing, it can be worthwhile. Mind you, EQ is a tool that only effects certain aspects of a soundfield, there are things that it can't do that passive treatments can, and vice versa.

 

[Hattrick]

Define "system bypass crossover".

Bad grammar. I fixed it. I meant for one to eliminate the cross over for the tweeter and lower frequency drivers utilizing EQ.

 

[Hattrick]

No reason not to, in my opinion. I'm using a professional loudspeaker management system for bass management and room/speaker EQ rather than using what my AVR has. It obviously requires more work and know-how than hitting "go" on Audyssey, Dirac, or whatever auto set-up is available to you, but if you're into that sort of thing, it can be worthwhile. Mind you, EQ is a tool that only effects certain aspects of a soundfield, there are things that it can't do that passive treatments can, and vice versa.

Good points. I watched a good video utilizing EQ in a home audio system. Most use it for cut versus boost. if there is boost utilized it is typically just a db or two above zero.

 

[restorer-john]

I meant for one to eliminate the cross over for the tweeter and lower frequency drivers utilizing EQ

It's been done for ~50 years in the analog domain.

Sony Esprit TA-D900

Accuphase F-25

 

[chelgrian]

There is so many speakers from budget bookshelf to outlandish flamboyant and insanely expensive. So...., why not just build a system which one eliminates crossovers and use external EQ? How about utilizing this for room correction, versus room correction software and or external wall, ceiling, and floor treatments?

It's called a digital loudspeaker management system and has been standard in the pro audio world for two decades until everything went active in the pro world and the smarts went inside the box.

It simply wouldn't sell in the 'HiFi' world.

 

[tmtomh]

There is so many speakers from budget bookshelf to outlandish flamboyant and insanely expensive. So...., why not just build a system which one eliminates crossovers and use external EQ? How about utilizing this for room correction, versus room correction software and or external wall, ceiling, and floor treatments?

As noted above, there's no particular reason not to do what you're talking about, except expense and complexity.

But conceptually, you're absolutely right: DSP for room correction includes digital EQ and filtering, which is essentially the same thing one would use to electronically manage the crossover between different speaker drivers. Even more so, bass management when using a subwoofer already is what you're talking about, except what you're talking about is extended to the crossover between all the drivers.

There already are active crossovers available, both digital and as @restorer-john says, analogue.

What we don't yet have is a series of more mainstream, mass-market (or at least audiophile/DIY mass market) single-box devices or software packages that can do room correction, bass management and also total active crossover duty. That last bit is the tough one, simply because every speaker requires a different crossover network, and no software or one-box device could properly manage a speaker unless the manufacturer published detailed technical specs on the crossover (and the crossover inside the speaker could easily be bypassed).

Also keep in mind that lots of speakers have dual connectors on the back, but often this is for bi-wiring rather than true bi-amping. In other words, even if you disconnect the straps that connect the two sets of speaker binding posts to each other, this does not disable the internal passive crossover circuitry in most speakers.

 

[RayDunzl]

So...., why not just build a system which one eliminates crossovers and use external EQ?

If starting with a stereo system you'll have to add and manage more hardware.

First step might be to add external EQ/DSP/Correction into the existing chain.

That got me far enough to keep me happy.

 

[wwenze]

Your room correction mic is not as good as a spinorama, so let the manufacturer handle the EQ. You still can do the room correction.

 

[fpitas]

Another active crossover system here. See my signature for details.

 

[Hattrick]

As noted above, there's no particular reason not to do what you're talking about, except expense and complexity.

But conceptually, you're absolutely right: DSP for room correction includes digital EQ and filtering, which is essentially the same thing one would use to electronically manage the crossover between different speaker drivers. Even more so, bass management when using a subwoofer already is what you're talking about, except what you're talking about is extended to the crossover between all the drivers.

There already are active crossovers available, both digital and as @restorer-john says, analogue.

What we don't yet have is a series of more mainstream, mass-market (or at least audiophile/DIY mass market) single-box devices or software packages that can do room correction, bass management and also total active crossover duty. That last bit is the tough one, simply because every speaker requires a different crossover network, and no software or one-box device could properly manage a speaker unless the manufacturer published detailed technical specs on the crossover (and the crossover inside the speaker could easily be bypassed).

Also keep in mind that lots of speakers have dual connectors on the back, but often this is for bi-wiring rather than true bi-amping. In other words, even if you disconnect the straps that connect the two sets of speaker binding posts to each other, this does not disable the internal passive crossover circuitry in most speakers.

Thank you great points.

 

[restorer-john]

What we don't yet have is a series of more mainstream, mass-market (or at least audiophile/DIY mass market) single-box devices or software packages that can do room correction, bass management and also total active crossover duty. That last bit is the tough one, simply because every speaker requires a different crossover network, and no software or one-box device could properly manage a speaker unless the manufacturer published detailed technical specs on the crossover (and the crossover inside the speaker could easily be bypassed).

I've often considered this concept and come to the conclusion the product could easily exist now, but due to commercial considerations, it just wouldn't be viable or practical.

Imagine you have a system where you have complete in room analysis, loading of driver/speaker parameters, filter and even perhaps cabinet design and several channels of amplification all in one 'magic' box.

The speakers you buy come with a set of parameters you load into the 'magic' box. Just like plugging in a game cartridge into a console. Then you run the in-room analysis and the device makes adjustments for both the placement and the entire room.

It's been touched on in the analog domain in the early 90s by Yamaha with their Active Servo Technology amplifiers and dedicated AST loudspeakers. They created a range of speakers with very simple 1st order Xovers for the tweeters and each came with a unique customised AST cartridge, which plugged into the rear (or front on some models) of the AST integrated amplifiers. It used a combination of negative impedance drive and customised EQ for the attached speaker to give an amazing performance from very small and interesting speakers.

At the time, there was talk it would go digital, incorporate DSP and have in-room analysis. That never happened until years later with their YPAO in HT receivers.

Unfortunately, the AST range wasn't introduced at the right time (post Japanese crash) and pretty much all the inventory was dumped here and sold very cheaply. They kept AST in their subwoofers for many years IIRC.

 

[Doodski]

I've often considered this concept and come to the conclusion the product could easily exist now, but due to commercial considerations, it just wouldn't be viable or practical.

Imagine you have a system where you have complete in room analysis, loading of driver/speaker parameters, filter and even perhaps cabinet design and several channels of amplification all in one 'magic' box.

The speakers you buy come with a set of parameters you load into the 'magic' box. Just like plugging in a game cartridge into a console. Then you run the in-room analysis and the device makes adjustments for both the placement and the entire room.

It's been touched on in the analog domain in the early 90s by Yamaha with their Active Servo Technology amplifiers and dedicated AST loudspeakers. They created a range of speakers with very simple 1st order Xovers for the tweeters and each came with a unique customised AST cartridge, which plugged into the rear (or front on some models) of the AST integrated amplifiers. It used a combination of negative impedance drive and customised EQ for the attached speaker to give an amazing performance from very small and interesting speakers.

At the time, there was talk it would go digital, incorporate DSP and have in-room analysis. That never happened until years later with their YPAO in HT receivers.

Unfortunately, the AST range wasn't introduced at the right time (post Japanese crash) and pretty much all the inventory was dumped here and sold very cheaply. They kept AST in their subwoofers for many years IIRC.

We had very good coverage on the Yamaha AST stuff. We had AST mini-systems, AST ghetto blaster, AST clock radio (I think we did.) and home system speakers with AST and subwoofer. The mini systems cost about $800 to $1200 but many customers where comparing them to a home stereo and good for condos and such. I had the larger AST mini system and never even took it from the box because I won it in a sales contest and I sold it in the Vancouver Sun newspaper within 3 days of listing it. The guy that bought it was very very stoked up about the deal and was unbelieving that he had hooked up with a stereo gear salesperson selling the model he was interested in buying. LoL.

 

[tmuikku]

EQ is in electric domain, one dimensional, while sound in room and listening position is in 3D acoustic domain. A speaker radiates sound to all directions and due to wavelength varying from great to tiny, which affects how physical objects with static physical dimensions interact with it. Result is frequency response varies with observation angle. EQ affects all directions equal amount.

Add x reflections in room before sound that left to a particular direction hits listener ear with some delay, attenuation and frequency response.

For this reason you are always going to benefit from good physical/acoustic design of the speaker and room treatment, as EQ cannot fix them. Still, there is many things EQ can help with, like reduce bass boom, apply delays and what not, of course handle the whole crossover. DSP seems always a good thing and could ease out some acoustic issues, but it just can't fix acoustic problems, they need to be fixed acoustically.

 

[dualazmak]

There is so many speakers from budget bookshelf to outlandish flamboyant and insanely expensive. So...., why not just build a system which one eliminates crossovers and use external EQ? How about utilizing this for room correction, versus room correction software and or external wall, ceiling, and floor treatments?

Actually, I have been doing exactly what you are suggesting in my PC-DSP-based multichannel multi-SP-Driver multi-amplifier stereo audio project.

You would please find my latest system setup here and here.

And, please find here (on my project thread) and here (remote independent thread post) the Hyperlink Index of the project as well as some of my related posts on remote threads.

 

[tinnitus]

Voila here is the "black box" (in the middle) that provides DSP and streamig. I have been doing room measurements and speaker measurements for over 10 years.
Since I also build loudspeakers myself I also create the crossovers. In the blackbox works a RPI 3b+ with the convlution software camilladsp fed with the FIR filters (65K Taps) from the ((acourate)) software. This software is the "german audio knife". Filter generating is the more difficult and individual part of the whole system, which in principle has to be done only once with measurements of the room. And I believe that this is the hurdle that will prevent the further spread of digital crossovers.
Maybe one day it will be possible to buy this measurement service and then you will have your individual filters without having to measure them yourself. Otherwise, the acquisition of measurement software/audio interface/microphone+stand/and cabling and training still comes on top of it.

 

[ocinn]

It's called a digital loudspeaker management system and has been standard in the pro audio world for two decades until everything went active in the pro world and the smarts went inside the box.

Side note, outside of Meyer, almost every festival-grade active PA box has the processing and crossover done in networked amplified controllers (LA12X, D80, etc..), not on a plate amp.

Outboard processing is still widely used for smaller deployments. Even huge names like L'Acoustics still sell the P1, Harman with the Lake LM44, etc...

 

[Hattrick]

Side note, outside of Meyer, almost every festival-grade active PA box has the processing and crossover done in networked amplified controllers (LA12X, D80, etc..), not on a plate amp.

Outboard processing is still widely used for smaller deployments. Even huge names like L'Acoustics still sell the P1, Harman with the Lake LM44, etc...

Thank you. It sounds like for a stereo system with Pre outs a stereo Graphic or Parametric EQ can be used to sweeten the sound of ones speakers to the listeners preference. But in a HT environment best to just use processing of the AVR.

 

[ocinn]

Thank you. It sounds like for a stereo system with Pre outs a stereo Graphic or Parametric EQ can be used to sweeten the sound of ones speakers to the listeners preference. But in a HT environment best to just use processing of the AVR.

Yeah, but I'd do it with DSP, not an analog graphic EQ. MiniDsp 2x4HD/DDRC-24 is the starting point and allows you to do correct subwoofer integration/crossover.