Why do you need a speaker crossover - discuss

[Dr Bunsen Honeydew]

I must admit even I might baulk at how big Paul speakers must be to achieve this
Richard I for one would be interested in what you done if people want to see an agenda so be it.

OK be it on your head, I predict the vultures will fly.

Three versions, a small one (on the floor) with 6inch bass/mid, a middle one with 8inch bass / mid and a larger one with two 8 inch bass / mid in an isobaric configuration.

As I say unless the price of acrylic fabrication comes down I doubt there will be more of them built and the cabinet is an intrinsic part of the design, so wood will not substitute without substantial rework. Three customers have early prototype pairs of the middle ones one in the UK one in Luxembourg and one in Belgium. I have the smaller and middle ones listed at ebay because I have one spare pair of cabinets for each.

The latest work I have done has taken them forward from when the prototypes were shown as Scalford two years ago and at Whittlebury last year.

[Dr Bunsen Honeydew]

Interesting Paul, The B200 is a good driver is it not? They are used in my OB's, along with a pair of 15" Eminence Alpha bass helpers per side.

The B200 is what Guy (Pure Sound) referred to earlier as the plastic horror. I will leave it at that and not tell you what I think.

[pure sound]

No. the Visaton B200 looks to be quite a nice driver & with a relatively high Qts should work well in OB.

http://www.visaton.de/en/chassis_zub...nd/b200_6.html

But I'm also interested to know why its higher o/p in the mid wouldn't sum just as the bass end does and why it wouldn't start beaming quite alot higher up.

[Dr Bunsen Honeydew]

No. the Visaton B200 looks to be quite a nice driver & with a relatively high Qts should work well in OB.

http://www.visaton.de/en/chassis_zub...nd/b200_6.html

But I'm also interested to know why its higher o/p in the mid wouldn't sum just as the bass end does and why it wouldn't start beaming quite alot higher up.

Whoops! sorry I presumed the B200 was the Kef B200.

[John]

I yet to hear those Richard so no idea how welll it works
For me I am very happy with my non WAV open baffles but admit I think my passive xover gets in the way a bit. The Crystals offer more resolution (no xover) but need careful partnering whilst mine are a bit more forgiving
I am still very interested in what Paul has done but think those speakers must be huge and I saying that being very happy with 2 x 15" drivers per speaker

[anthonyTD]

You could argue that my open baffle line source arrays use mechanical solutions for tricky issues. I use Visaton B200 drivers and their individual response curve is anything but flat through the audio band, although I suspect these curves were produced from drive units that were fresh off the production line and not run in. After a month or so of run in the ragged top end smoothes out considerably and the drive unit sounds more coherent through the audio band. The bass end of an individual drive unit is lightweight due to the falling response, but happily, when mounting eight drive units in a vertical array, the parallel operation of the drive units gives a large boost in efficiency in the lower mid and bass end, which reinforces the bass very nicely in a way that evens out the bass/mid response to the point where I do not feel the need for subwoofers. The bass goes very deep when there is deep bass in the program and there is no cabinet honk or restriction as the arrays are open baffle. A well recorded kick drum sounds like a kick drum and I should know what this sounds like as I usually stood near to the drummer in the group I used to play in as a youngster.

Line arrays have benefits regarding reduced room interaction due to the way they propagate energy into the room. This is another mechanical solution to reduce an age-old problem of room interaction.

I have to admit that the top end rolls off a little earlier than many would require, however this can be a blessing with some program especially from digital sources, and the treble is nicely coherent.

The near field amplitude response of the line array falls off at only 3 dB for every doubling of distance whereas a point source propagating a spherical wave front falls off at 6 dB per doubling of distance. This adds further to the overall efficiency in a beneficial way. The very high efficiency of the lines means I only need a few watts to achieve concert levels, which is a nice side effect of the parallel drive units and the effects of the way the wave front is propagated into the room, which is once again a result of a mechanical solution.

Using eight drivers per channel means the lines can move enough air for concert levels without extreme cone excursions so the distortion levels of the drive units are very low.

So effectively I have moved away from complexity by implementing mechanical solutions in the loudspeaker design to minimise components in the signal path. There are no crossover components in the arrays. This has benefited the electronics too and my power amp has one mosfet and one resistor in the direct signal path and my line preamp is an LDR L-pad with one LDR directly in series with the signal. There is just no need for any voltage gain in these sections.

This works for me and I have not felt the need to work on the speakers or amplification for over four years. Prior to that I was always fiddling around spending vast amounts of R&D time looking for improvements.

Out of interest the system is great for home cinema duty too and some of the sound effects in the blockbuster films can be awesome.

Paul

hi Paul,
A very intersting aproach.
i have experience of some linear arrays and their potential.
however, not on the scale of what you describe.
So,,,picks please [when you get chance] you have my full attention now!
Anthony,TD...

[Ali Tait]

Open baffle is the ultimate solution if you are completely nerdy, have got a separate play room, don't have a wife, etc. I can't cater for that nor can anyone else even in a mildly commercial situation. Even horns are limited choice due to these factors.

Now I know I have railed against WAF speakers but there has to be compromise of sorts aesthetically. I am avoiding showing pics as I know I will be accused of something if I do.

Well I wouldn't call myself a nerd, and my partner is quite happy having a pair of large OB's in the lounge, as she loves the way they sound. In fact, not only are the OB's in the lounge, behind them are a pair of 2m tall electrostatics. She's a good lady.

[aquapiranha]

Richard, can you give us more details about the drivers? If you would like to keep that info confidential I would understand.

[technobear]

No. the Visaton B200 looks to be quite a nice driver & with a relatively high Qts should work well in OB.

http://www.visaton.de/en/chassis_zub...nd/b200_6.html

But I'm also interested to know why its higher o/p in the mid wouldn't sum just as the bass end does and why it wouldn't start beaming quite alot higher up.

Quite a few on DIYaudio have removed the dust cap and replaced it with a phase plug. It is said this reduces the beaming and improves them no end.

[Dr Bunsen Honeydew]

Well I wouldn't call myself a nerd, and my partner is quite happy having a pair of large OB's in the lounge, as she loves the way they sound. In fact, not only are the OB's in the lounge, behind them are a pair of 2m tall electrostatics. She's a good lady.

Then count your blessing, with most it would lead to divorce if it was in the living room.