GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Audio Discussions
In the Thread: Constructing LF modules to the limits

Post Subject: My direction is 2x4" + 12" + 2x15" + 4x23"Posted by haralanov on: 9/22/2011

Romy, I do agree with all your comments.
It is true that the magnitude of the rubber taste very much depends on the crossover frequency. I used them below 64Hz, but with first order filter, implemented before the amp that drives them. With that kind of setting there is very slight rubber taste, and it is absolutely not annoying, but it is there and I’m able to hear it. I intentionally do not use steeper filters. I very much like the way how bass arrays portray the low frequency scale and size. A pair of woofers listened at 90dB are far below the level of sonic 3D effect (sorry for the stupid phrase, but I cannot describe it accurately in English) which one gets by listening to an array of 4 woofer pairs, listened again at 90dB. With arrays, bass has size and physicality – not only SPL level, as is the case with only one pair of woofers. But you know all that much better than me, because you are listening at bass arrays for years. The point is to have as much radiating surface through the vertical plane as possible.
I will move to live in my house in the province and I have quite a big room there, which I will use only for listening (it has solid floor and quite a good acoustics) so I can afford to put as much woofers as I want, and may be I will end up with 8 x 23” woofers in order to have very even bass response at my listening chair.

oxric wrote:
I wish you good luck with the wide-range effort

Thanks, I will need it :-)
I had 12” wideranger that sounded almost the way I like, but unfortunately I blew it up. It was 102dB sensitive, but the feeling was it is 122+dB sensitive. A couple of months ago I was in very good mood and I had desire to listen very enjoyable big band music at very loud levels. After 10 minutes of listening at these levels, my mood got even higher and I turned up the volume until the sound became so loud, that my brain refused to believe it is possible. Generally speaking, most of the drivers distort before they burn, but it was not the case. The sound was ultra loud, with absolutely no stress or distortion and with absolutely no sign it will burn. But there was a fragment, where there were playing simultaneously several sub trombones, several trumpets, tuba, double bass and suddenly the voice coil literally flied out of the magnetic gap disentagled in the air and the former went in fire. I was listening at more than 120dB…
Then I made second attempt to make such a driver, with the intention to improve it further:

I made several mistakes, but unfortunately I realized them after I finished the driver. It does not have that sense of unlimited effortlessness and freedom of sound and even more important – it doesn’t have the fresh breeze effect that I’m looking for. Now I prepare third version of that driver. I hope it will be the last one……….

oxric wrote:
My own personal exposure to widerange drivers has never been very positive but the theoretical benefits of such a design cannot be denied.

That’s because there are no good widerange drivers out there, for any amount of money. And I wish I was kidding…

oxric wrote:
an 18" driver is equivalent to roughly 3x10" and a 23" driver to 5x10" drivers in terms of cone area, so I can see the benefit of going for 4 such drivers equivalent to 21 10" drivers no less.

Rakesh, what you said is accurate, but I’m switching to 23” drivers, not because they have big radiating area, but because of the more accurate behavior of that big radiating area. It may sound childish, but I really want my bass drivers to do strictly what my bass amplifiers tell them to do. I simply prefer speakers which do not have their own “intelligence” at/around their Fs.

oxric wrote:
I hope that your driver, if you mean for it to be commercialised can be used to good effect in a smaller enclosure!

It will never be commercialized. What I’m doing in audio is with only one purpose – to make the sound in my room closer to the sound in my imagination. I will not sell anything.
Second of all, I will intentionally make its T/S parameters to be optimized for a very big enclosure. I know someone is going to tell me I am stupid to do so, when I have a chance to make it to work with much smaller enclosures. Well, as you might have guesses – there is a reason behind that decision. The reason is that the loading in front of the cone will be symmetrical to the air loading behind the cone. This technique lowers the distortion a lot and prevents impedance and phase anomalies. This is important.
The size of the enclosures is not a real problem for me and when I find the place in my room where these woofers sound at their best, I will construct the enclosures from double brick walls with 4-5” sand filling between the walls. And of course they will be fixed with absolutely no option to be moved because of the several ton of weight. But I truly hate to speak in “future time”, so when everything is done and ready for listening, I can eventually post my impressions here.

Best regards,
Haralanov

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