Classic monitor designs?

And they both sound wonderful.
Even with my own speakers that are controlled with modern DSP I can't help but put in a bit of character in the mid range. Something I loved of the big old JBL and Altec speakers. A hint of it is enough. Too much and it kills the details. A touch of warmth. I don't care if its wrong. It is to please me as the end user.
No flimsy thin sound for me... big balls :).
 
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You want accurate response, with as little coloration as possible in the studio.
But years ago, I came to the conclusion this is not what I want at home for long listening sessions to a variety of source material that may suffer from all sorts of imperfections.
That touch of warmth makes a big difference.
 
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Obviously, I am not talking about major deviations from "the ideal", but something along the lines of Troels' tiny XO tweaks by playing around with different resistor values.

I'd rather do that in the drive electronics, somehow that seems a more appropriate place as you can control things at smaller power levels than in the XO.
 
This is one of my backburner projects, which I have been playing around with.

This old Monitor Audio MA7 12L reflex box:

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It seems to have improved with a bit of run-in. I'm not surprised, because electrolytic capacitors that get no voltage lose their insulating layer over a few months. It's a chemical thing IIRC.

The simulation is not exact, but close enough to tell us what goes on. It, like the classic BBC LS3/5A is a BW3 design. You really ought to know about BW3 in a World that seems obsessed with LR2 and LR4. See, 90 degree BW3 phase is a constant power filter. You can get impedance exactly flat with a bit of effort.

And it sounds good all round the room. No deep nulls above and below axis.

I'm growing to enjoy this paper bass 5" speaker in the near field of a small room. The bass is really very good. And my modelling suggests it (third Order) might work well with the notoriously difficult 6" bass. I have very little time for soft domes, but those old 3/4" mylar tweeters work well. They just don't seem to make 'em any more. :mad:

Couple of good driver selections by Troels, not that I'd use his filter ideas. This idea is better, IMO. http://www.diyaudio.com/forums/multi-way/147632-classic-monitor-designs-45.html#post5139615

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Peerless HDS PPB 830860
Vifa PL14WJ-
 

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Since 80-90% of the World's speakers have soft domes, I'd possibly offend a lot of people by suggesting there is a better way of doing things. Nobody wants to hear this sort of thing. :eek:

But here's a history lesson. 50 years ago or so, most speakers used 2-3" cone tweeters. And very fine they sounded if implemented well. But they fell off badly off-axis. Very directional, you see. Enter the 1" soft-dome, mainly by Philips. Great dispersion off-axis. But not so musical. Not so engaging into the audio-illusion of the live performance.

I read Robin Marshall years back on rigid metal domes versus soft-domes: Robin Marshall: A Modicum of Genius | Stereophile.com

The problem with soft-domes, IMO, is the centre of the VERY floppy soft-dome plays different tunes from the edge. Sometimes it is moving in the opposite direction from the edge. This, IMO, ADDS distortion, whereas some other types simply dip into silence due to more damping applied.

Back in Robin Marshall's day, ring-radiators were unheard of, but pinning the uncontrolled soft-dome centre seems like a plan if you avoid the more rigid metal types. We now have Vifa XT25 and SB Acoustics soft material ring-radiators, below.

I am forming some theories these days. I think flat impedance is a good thing, especially for cheap amplifiers. And I have built a lot of exotic amplifiers, so I'm no fool about how difficult they can be to keep stable with certain electrical loads. I think BW3 is a good thing that musical types like, who know how live music sounds.

Classic monitors is about the tested ideas that work well. Here's the waterfall plot of a very high-end Morel soft-dome. A lot of nasties there, IMO. I've never had much luck with my similar soft-dome Morel CAT298 tweeters. Everything else worked better. Monacor HT-22/8 Cones and Visaton DT94 Mylar and aluminium SEAS 19 TAF/G included.
 

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Surely the problem with soft domes is much the same as with midrange drivers, which are mostly used well outside their pistonic range too, and dealing with cone breakup modes is accepted as being critical to clean performance.

That Morel is obviously poorly designed! Here is a waterfall plot (not my measurement) for the SEAS 27TFFC soft dome I used in Troels' 3-Way Classics:

An externally hosted image should be here but it was not working when we last tested it.


MUCH cleaner than the Morel.

Alex