2-way with active biamping ideas

[breez]

Hello

I'm looking for advice and ideas on building and designing a pair of small 2 way speakers. Originally I thought about buying another pair of commercial speakers, but this time I'm looking for something different. Namely, biamping and digital crossovers.

I already have a room correction system in place with possibilities to expand. It consists of a standalone Linux PC with brutefir running filters generated with DRC. I have been reading about the benefits of active biamping and it would be only natural to move to digital crossovers easily implemented with the system.

Since I have little room to spare I need small speakers. Listening will be nearfield. This limits me to normal box speakers 2 way or full range.

At first full range seemed like a good candidate, no crossover of any kind at all! But apparently full range drivers don't usually fare too well with 'busy' music (metal, orchestra etc.) so I discarded that option. This leaves me with the basic small 2-way box design.

Most 2-way designs involve a bass woofer crossed over with a tweeter somewhere in the midrange. The crossover point is a compromise to satisfy the limits of the drivers. Is a crossover at 2-3KHz 'optimal' for sound quality? I've read about 'intelligence band' around 300-3000Hz and placing a crossover there would be detrimental to sound quality. Is there any truth to this? Based on science and research?

Now having the above in mind and while considering full range design I stumbled upon Jordan drivers, particularily the JXR6. It is supposed to have usable frequency range from 100Hz to well above 20KHz. Now this could crossed over very low compared to conventional 2 way design. Benefits would include not having to place it in the 'intelligence band' and not having to worry about woofer directivity. Any disadvantages?

For a suitable woofer I've been looking at www.zaphaudio.com and found Seas L16RN-SL from the 5-5.5" woofer comparison page. Low distortion, good extension and recommendation to use with a low crossover caught my eye. I plugged the T/S paramters in WinISD and got a nice looking extension in a small ~8L closed box (-3dB ~60Hz).

Any other suggestions for drivers? Or the design in general? The drivers seem a bit expensive, but at first I was seriously considering commercial speakers in the range of 500-700€ anyway

[terry j]

Originally posted by breez
[B

Most 2-way designs involve a bass woofer crossed over with a tweeter somewhere in the midrange. The crossover point is a compromise to satisfy the limits of the drivers. Is a crossover at 2-3KHz 'optimal' for sound quality? I've read about 'intelligence band' around 300-3000Hz and placing a crossover there would be detrimental to sound quality. Is there any truth to this? Based on science and research?

Now having the above in mind and while considering full range design I stumbled upon Jordan drivers, particularily the JXR6. It is supposed to have usable frequency range from 100Hz to well above 20KHz. Now this could crossed over very low compared to conventional 2 way design. Benefits would include not having to place it in the 'intelligence band' and not having to worry about woofer directivity. Any disadvantages?

I run a three way, and use the deqx so we have similar capabilities.

For quite a long while, I too applied the 300-3000 hz critical range theory and I was quite happy with it. I crossed the mid in at 300 and the tweeter at 3000. ( the lower limits on my mid won't allow me to go much lower anyway, doubtless you will be using a 'mid' that can go much lower so what I say only applies to the mid/tweeter x-over point)

Very recently, I had the good fortune to have the deqx tech guy come out to my place (he demoed the new version of the deqx) and so during the course of the day we remeasured my speakers and applied new x-over points.

It gets a bit tricky to isolate which change did what (the new measurements and measurement technique greatly improved the filters applied to the drivers), but we also changed the x-over frequency on the mids to 200 hz and 1650...and the change was dramatically better!! Much more open, much cleaner and less strained (esp at higher levels) and a much much larger spacial presentation (which was always pretty good). Sure, with the deqx we can use rather steeper slopes than most, but I assume you can too?

Maybe the 300-3000 rule applies to the old way of doing things with passive networks?? Dunno. I guess all I'm saying is that at times we can get caught if we follow 'accepted and standard thinking'.

So, don't be scared to try something different, the improvements in that case were for me dramatic.


Don't know what the response of the Jordan looks like, but any full ranger I've ever seen has a very very rough FR. If you are committed to lessening the compromises that passive crossovers bring then I can well understand people using them, but when you can go active (while not introducing phase and summing errors like the deqx does, and I assume your setup as well??) then the 'need' for a full ranger with all their associated compromises is greatly decreased...all in my opinion of course.

[breez]

Originally posted by terry j
Sure, with the deqx we can use rather steeper slopes than most, but I assume you can too?

Maybe the 300-3000 rule applies to the old way of doing things with passive networks?? Dunno. I guess all I'm saying is that at times we can get caught if we follow 'accepted and standard thinking'.

So, don't be scared to try something different, the improvements in that case were for me dramatic.

Yes, any filter topology should be possible with FIR, including steep linear phase filters. With such brickwall filters there should be essentially no overlap between the drivers.

The disadvantage is preringing in the time domain and I wonder about its audibility and where in the frequency range ear is most sensitive to it. Of course one can trade in steepness for less ringing to get the best compromise.

Don't know what the response of the Jordan looks like, but any full ranger I've ever seen has a very very rough FR. If you are committed to lessening the compromises that passive crossovers bring then I can well understand people using them, but when you can go active (while not introducing phase and summing errors like the deqx does, and I assume your setup as well??) then the 'need' for a full ranger with all their associated compromises is greatly decreased...all in my opinion of course.

Indeed there is some FR roughness in the highs (6+ kHz).

http://www.ejjordan.co.uk/drivers/jxr6-graphs.html
http://www.diyhifisupply.com/docs/JX...0Para%2006.pdf

A wide range driver for mids and highs would give more freedom to experiment with crossovers than a tweeter could (in a 2-way).

Anyway, thanks for the input terry j!

[terry j]

Originally posted by breez

The disadvantage is preringing in the time domain and I wonder about its audibility and where in the frequency range ear is most sensitive to it. Of course one can trade in steepness for less ringing to get the best compromise.

Re the pre ringing, that WAS one of the things the deqx guy changed as well, lowered the crossover slopes I was using, the reason cited was that for the types of drivers I had the slopes were too steep and that raised the potential problem of pre-ringing. Something about (for example ribbons) using steeper slopes on really fast drivers. Way over my head but looks like you're on top of it.

With all the other simultaneous changes I can't tell you the magnitude of that exact change, but it's interesting that you have mentioned it.

No, those graphs were no where near as rough as I suspected.

Good luck with it, I can see you're way ahead of me from now on and so I have no more to offer but good wishes!!

[D OB G]

Hi Terry,

I'm waiting (and waiting!) to take delivery of the DEQX PDC3, which is what I presume was demoed?

What crossover slopes did you end up using for the
-tweeter
-midrange?

David

[Zarathu]

You can't do 300-3000 cross with any normal speaker system. There is no midrange that will handle that range without distorting, and without severe loss of clarity.

I have a set of 17-speaker 3.5 inch 3.5mm Xmax wide range middies in my line array(34 total with both speakers), and they do beautifully at 165-2500, but only because the whole system from each one only carrying 5.8% of the total load to the specially designed individual cabinets for each to the electronic crossovers with 24 db slopes to the separate amp just for the midrange--- can it work with any reality.

In any other system if you want clarity in the midrange, you cannot cross much higher than 1600hz. And if the mids are much bigger than 4 inchers, anything above 1600hz is too much for them.

My opinion, of course.

Zarathu

[terry j]

Originally posted by D OB G
Hi Terry,

I'm waiting (and waiting!) to take delivery of the DEQX PDC3, which is what I presume was demoed?

What crossover slopes did you end up using for the
-tweeter
-midrange?

David

yeah the deqx guy demo'd the pdc 3.0 Let's just say it was an improvement shall we? A very nice improvement.

W/out pulling it up to see, they're only about 60 db or so in the end, both of them. I'm trialling some Raal ribbons this weekend, we may steepen the slope on the tweeter, we'll see.

Originally posted by Zarathu
You can't do 300-3000 cross with any normal speaker system. There is no midrange that will handle that range without distorting, and without severe loss of clarity.

My opinion, of course.

Zarathu

I've come to agree with you. Not sure about distorting, in my case I feel the improvement may have come not so much from running the tweeter lower, but the flipside of not running the mid so high.

That's only a guess though.

[cabbagerat]

Originally posted by breez


Yes, any filter topology should be possible with FIR, including steep linear phase filters. With such brickwall filters there should be essentially no overlap between the drivers.

The disadvantage is preringing in the time domain and I wonder about its audibility and where in the frequency range ear is most sensitive to it. Of course one can trade in steepness for less ringing to get the best compromise.

The most obvious disadvantage with steep FIR filters is group delay (this applies to IIR to, but in a different way). Steep linear phase filters require large filter order, and the group delay of a linear phase filter is half the filter order (for realtime applications).

If you match group delays it doesn't matter for music at all, but for movies you can visibly lose lip sync even with fairly short filters.

[sreten]

found Seas L16RN-SL from the 5-5.5" woofer comparison page.

Hi,

Have you considered the design that driver has been built for ?

http://www.linkwitzlab.com/Pluto/intro.htm

(SL = siegfried linkwitz)

/sreten.

[breez]

Originally posted by Zarathu
You can't do 300-3000 cross with any normal speaker system. There is no midrange that will handle that range without distorting, and without severe loss of clarity.

I have a set of 17-speaker 3.5 inch 3.5mm Xmax wide range middies in my line array(34 total with both speakers), and they do beautifully at 165-2500, but only because the whole system from each one only carrying 5.8% of the total load to the specially designed individual cabinets for each to the electronic crossovers with 24 db slopes to the separate amp just for the midrange--- can it work with any reality.

In any other system if you want clarity in the midrange, you cannot cross much higher than 1600hz. And if the mids are much bigger than 4 inchers, anything above 1600hz is too much for them.

My opinion, of course.

Zarathu

Interesting insight about the midrange. What are your thoughts on running the woofer in a 2-way a little higher than the proposed 300Hz and letting a wide ranger take the rest? I also run a subwoofer (BK Electronics XLS200, 10" XLS in small closed box). 100dB peaks and 85dB average level is what I'm aiming for.

Originally posted by cabbagerat
The most obvious disadvantage with steep FIR filters is group delay (this applies to IIR to, but in a different way). Steep linear phase filters require large filter order, and the group delay of a linear phase filter is half the filter order (for realtime applications).

If you match group delays it doesn't matter for music at all, but for movies you can visibly lose lip sync even with fairly short filters.

Yes, I have considered the constant delay from the filters. It won't be a problem though, I can delay the video. Video is not much of a priority anyway.

Originally posted by sreten


Hi,

Have you considered the design that driver has been built for ?

http://www.linkwitzlab.com/Pluto/intro.htm

(SL = siegfried linkwitz)

/sreten.

I noticed that design and while it is interesting it's not really suitable for me. I need to mount speakers slightly elevated on a desk.