Morel drivers...

How complicated the cross-over has to be is dependant on the way in which the drive unit behaves near/at/past the chosen cross over point. This is one area in which cone material becomes significant. The advantage of doped paper cones is that they have relatively high self damping properties and so tend to roll off quite smoothly at the top end of their usable frequency range. Generally this makes for easier integration with simpler cross-overs. The disadvantage is that you generally have to put up with higher THD/intermodulation components, (relatively speaking - as good ones are still pretty good in this area). Alternatively you can use metal cones as they are more linear and have lower distortion figures in general. However, they ring like ba(*&%(ds and have very poor cone break up characteristics leading to a very jagged and spikey response at the top end of the band. To prevent this part of the output to be audiable much higher order cross overs need to be used with all the potential phase problems which they incur. Hence the arrival of carbon/kevlar/composite (including paper composites) material use, which tread the middle ground between paper and most widely used metals.

With respect to the amount of drive units, well using more makes for a more complicated speaker with more potential to mess up the sound. Integration of the drive units is harder electrically as well as the physical constraints and acoustic implications of using multiple drive units has on the way the final speaker behaves. For example there is the issue of acoustic centre positioning for each drive unit and the potential smearing in the time domain due to physical distance between individual units and seating position etc. On the flip side, using less has the drawback of finding wide enough bandwidth units to conver the whole frequency range. Most drive units start to loose phase coherence at the extremes of their bandwidth, particularly off axis. Of axis response is more important than just the actual level involved, there are phase issues to contend with. All of these factors affect the way the speaker sounds when you move around. I'm sure we've all heard speakers that sound great in one spot only to start sounding "off" as you stand up, move from side to side, and im not talking about their ability to image here I mean from a basic frequency response/phase standpoint.

GTM

 

I was driving through a little village in leicestershire on Friday visiting a client, and BAM! there was wilmslow.

I didnt go in, but might next time.

Julian, its about 1 - 1.5 hours drive from yours.

Chris

 

chris,
unfortunately the money i'd earmarked for this bit of experimentation has been sucked up by the allure of a blue led. so i'm skint again and the b&w's will have to do for the time being. probably for the best as i'm a bit of a klutz when it comes to diy! still maybe in a few months time...
cheers


julian

 

Absolutely fabulous when I heard their Octwins on some Leonard Cohen and Yasser's take on the classic "Time Out"

 

In my DIY days I looked at Morel drivers and was distinctly unimpressed.

 

Well you need to have a design in mind to use any driver. Some of their tweeters work pretty low with good power handling. All of the famous names mentioned make high spec tweeters if you pay high prices. I can't see anything special about their LF-MF stuff.

2-ways are always going to be the favourite ,for the manuf. You get a good pricedeal if you can make a bass mid work in a few different boxes. Witness the fashion for lots of small bass/mid drivers in a box. Look at the peerless website - you need to buy 2000[!!] drivers per year to be a direct customer. Theres no point using a 10" or 12" 3 way unless its a top banana driver. This means you spend 15 times as much on the bottom 2 octaves as anywhere else. And the box construction need to be very heavy to make it worthwile.
Julian, you can make a DIY 3 way with a great 10" driver for about £400 - 450 pair, but it's a lot of hassle, and I haven't had time to finish my xover. I might take it to Isaacs anyway.

 

hmmm not sure about 3 ways, I think its like said b4 to do with

1/ fashion, small rooms, look nice, wives
2/ cost, 90% of homes simply have mini systems, no market for big ones, ie what you get back for what you put in.

For all the derision that goes around ,2 ways can't do bass, 3 ways are too complex,and can't integrate correctly.

you can't beat a good 2 way, they can be superb

yes 3 ways are more complex, but again, they can be good, its like everything, you get all this engineers theory, but it doesn't translate, you can get good and bad in anything even if the theory expresses reservations.

Jsut use common sense and your ears.

 

The fabulous sounding Vulcain Aida bookshelves use Morel midrange/bass drivers and Seas Excel tweets:
http://www.noir-et-blanc.be/pages_fr/produits/marques/vulcain/pr_vulcain.html# (Click on Aïda + Filtre)