Hi-End and Hi-Efficency loudspeakers (horn + onken)

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audiodesign

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Joined 2005
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This project born to create a good loudspeaker with very high efficiency and low cost.
To reduce the cost has been decided to use only 2 drivers with the lower crossover frequency possible.
A valid design of this type could be the BassZilla (here the complete project) but it is not cheap because F208ES need a tweeter and Lowther DX3 or DX55 are very expensive.
So I have decided to start with a 2 way using a compression driver loaded by a good horn and a 15" woofer to get high efficiency and good low frequency band.
To limit the cost I have decided to use 1" driver with an 800Hz crossover.
As horn has been used a good Tractrix model of the www.stereo-lab.de series.
The Beyma CP380M compression driver has been the first choice because it have a low distortion and a very linear frequency band.
Many DIY prefer this driver to other components because the sound of CP380M is very natural if compared to other compression driver (see http://www.speakerplans.com/FORUM/forum_posts.asp?TID=13807&PN=3 or http://nullspace.us/tt12.html or http://www.speakerplans.com/Forum/forum_posts.asp?TID=10871).
About the woofer we need a 15" with:
- a linear frequency band until 3-4KHz to prevent problem after the crossover frequency
- a moving mass no more than 90 gr to be fast
- a sensitivity near to 100dB
- a low resonant Frequency to have a good bass frequency band

See my starting search and give me suggestion about these.
http://www.audiodesignguide.com/HiEff/WooferCompare.html
 
#10
audiodesign said:
This project born to create a good loudspeaker with very high efficiency and low cost.
To reduce the cost has been decided to use only 2 drivers with the lower crossover frequency possible.
A valid design of this type could be the BassZilla (here the complete project) but it is not cheap because F208ES need a tweeter and Lowther DX3 or DX55 are very expensive.
So I have decided to start with a 2 way using a compression driver loaded by a good horn and a 15" woofer to get high efficiency and good low frequency band.
To limit the cost I have decided to use 1" driver with an 800Hz crossover.
As horn has been used a good Tractrix model of the www.stereo-lab.de series.
The Beyma CP380M compression driver has been the first choice because it have a low distortion and a very linear frequency band.
Many DIY prefer this driver to other components because the sound of CP380M is very natural if compared to other compression driver (see http://www.speakerplans.com/FORUM/forum_posts.asp?TID=13807&PN=3 or http://nullspace.us/tt12.html or http://www.speakerplans.com/Forum/forum_posts.asp?TID=10871).
About the woofer we need a 15" with:
- a linear frequency band until 3-4KHz to prevent problem after the crossover frequency
- a moving mass no more than 90 gr to be fast
- a sensitivity near to 100dB
- a low resonant Frequency to have a good bass frequency band

See my starting search and give me suggestion about these.
http://www.audiodesignguide.com/HiEff/WooferCompare.html
Click to expand...
A few things cross my mind when I read this, so I'll start at the bottom.

You seem to be focussed on low mass as a design priority, so maybe you should read these.
Dan Wiggins on Woofer Speed
Nick McKinney's take

I would concentrate on how the driver responds at the top of it's band.
High efficiency drivers often do not have very good LF as that is the tradeoff that happens in the Pro world where most of them are used. I have no experience with Onkens, but I have a hunch they will be a big box.

The AE's are excellent drivers, better made than any pro units that I've seen, and I've used a very large number of them.
Here is the only FR curve I can find, but email John and he may be able to send you more.
TD15M

Modelling the drivers of interest will let you know how they're going to work at LF, but you need to consider other fsctors as I mentioned at the top of the passband.

The CP380M is an excellent driver and one of my favourites. I have never used it as low as 800Hz, so I cannot say whether it will perform there or not. They may need to be crossed steeply or not given much power.

From your link to the Tractix horns, I presume you mean the 400Hz versions? trax horns do not really load the driver until about 1.4x the flare frequency in my experience and a 400Hz flare is going to beam very badly at HF.
 
#18
inertial said:
Hi Andrea,

A 15" + 1" ..... Why not take example from Summa loudspeaker( Dr. Geddes)? 😉

Cheers,
Paolo
Click to expand...

I thought that sounded familiar!


audiodesign said:
Summa loudspeaker use a 15TBX100.

not bad on low freq but with a strange peak on high freq. very difficul to compensate with low order filter
Click to expand...

Then don't use a low order filter.

audiodesign said:
Summa loudspeaker use a 15TBX100 with only 95db
Click to expand...

B&C says 96 dB, and you can believe that. With a lot of companies you can't trust the data sheets. With B&C you can. Living in Italy I can't understand why you wouldn't use their products as they are exceptional.
 
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