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Multi-Way Conventional loudspeakers with crossovers

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Old 2nd May 2007, 04:56 AM   #621
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Lynn,

How have you gotten derailed from your original plan of a full range hemp cone driver augmented by a true tweeter and woofer? I'm somewhat to blame for the sidetrack, but as much as I like horns I think this is a better idea than crossing to a horn at 1-2khz. Just my opinion, of course!

Jeff
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Old 2nd May 2007, 05:29 AM   #622
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Quote:
Originally posted by jeff mai
Lynn,

How have you gotten derailed from your original plan of a full range hemp cone driver augmented by a true tweeter and woofer? I'm somewhat to blame for the sidetrack, but as much as I like horns I think this is a better idea than crossing to a horn at 1-2khz. Just my opinion, of course!

Jeff
Well, Jeff, you must have been reading my mind. I was just ambling through the web, and came up with this combo: the Tone Tubby 12" Alnico, with the Fountek NeoPro 5i, augmented with the 15" driver of your choice (maybe the Tone Tubby 15" driver) in a short open-ended box filled with recycled cotton. The 12" wideband driver and the ribbon tweeter would be on an asymmetric open baffle, similar to the shapes shown before, with the tweeter 40" high off the floor.

Crossover is simplicity itself: an acoustic 12 dB/octave crossover between 2~2.5 kHz, depending on how the drivers want to be crossed over (you come in a bit early on the TT, probably 1.5~1.8 kHz, to offset the steep rise at 2 kHz). The net result would be an acoustic crossover where the TT curve flattens out again, in the vicinity of 2.2~2.5 kHz.

The ribbon tweeter would be quite happy with a 2.2~2.5 kHz 12 dB/octave electrical crossover. I might steepen the tweeter HP slope (to 18 or 24 dB/octave) to assure an in-phase relationship between the widerange driver and the ribbon tweeter. This can be confirmed by temporarily reversing the phase of the tweeter and looking for a null - I usually try for a 20 dB null at the acoustic crossover frequency. The larger, floor-mounted bass driver comes in around 200 Hz or so, and augments the 12" driver to offset its 1/f dipole loss.

After careful crossover adjustment, the net response should fall in a +/-3 dB window, and be adjusted to taste. I usually aim for a 1~2 dB tilt from 100 Hz to 10 kHz, with a slight bass emphasis. Net response of the system, depending on size and filling in the bass module, would be from 70~80 Hz to 30 kHz, with efficiency set by the 12" TT, around 98 dB/metre.

Nice alternative to the US$20,000 Verity discussed elsewhere, eh?
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Old 2nd May 2007, 07:12 AM   #623
Variac is offline Variac  United States
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This latest seems more in keeping with your original ideas, and a lot easier for others to replicate. Probably a lot cheaper too, and based on a topic that is on the minds of lot's of people.

-I think you have about three good systems in mind and you should probably do them all , but I vote for something similar to this one first!
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Old 2nd May 2007, 07:13 AM   #624
fiacono is offline fiacono  Australia
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Since I have two of those drivers at home I will try it out night (except for the 15"TT).

Currently I have the 12" TT Alnico crossed at approx 1.5K/12db and the Neo Pro 5i coming in about 3.5K at 18db. Another 12"TT (temporarily until i place my order for the 15" TT ) for the bass.
I tried the NeoPro5i at 12db but didn't like it (loss of sparkle) but then I may have done something wrong (interaction with the TT).
On the other channel I'm running the ME2's (separate volume control) to compare.
Don't have any measuring equipment..

Frank.
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Old 2nd May 2007, 07:28 AM   #625
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Lynn,
Im wondering if you feel you have identified to any extent the design aspects of the Bastani Apollo which were responsible for your revelatory experience with them.

Specifically, I'm wondering to what extent the Apollo magic relied on a high crossover frequency to the tweeter (or complete lack of crossover within its natural passband) and whether, by straying into lower crossover frequencies in a non-coaxial configuration this advantage is being threatened.
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Old 2nd May 2007, 08:46 AM   #626
ScottG is offline ScottG  United States
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Quote:
Originally posted by Lynn Olson


Well, Jeff, you must have been reading my mind. I was just ambling through the web, and came up with this combo: the Tone Tubby 12" Alnico, with the Fountek NeoPro 5i, augmented with the 15" driver of your choice (maybe the Tone Tubby 15" driver) in a short open-ended box filled with recycled cotton. The 12" wideband driver and the ribbon tweeter would be on an asymmetric open baffle, similar to the shapes shown before, with the tweeter 40" high off the floor.
The Neo5 is rather like a wide horizontal dispersion narrow vertical dispersion BMS driver.. clean, detailed.. but lacking when compared to other true ribbons (..rather like a planar in fact, but with better vertical dispersion).

The Aurum Cantus G1 (though measuring poorly by comparison), sounds more natural with its non-reinforced ribbon.

Frankly what you R E A L L Y want is not a std. production unit.. This is the Co. you should contact for that perfect custom "fit" and a base technology that surpasses the rest (audibly and measurably):

http://www.raalribbon.com/products.htm

..still, its too bad DDS doesn't seem to be in standard "business" anymore. I could have directed you to a VERY nice horn that would have provided the correct polar patterns.
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Old 2nd May 2007, 08:52 AM   #627
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Quote:
Originally posted by Russell Dawkins
Lynn,
Im wondering if you feel you have identified to any extent the design aspects of the Bastani Apollo which were responsible for your revelatory experience with them.

Specifically, I'm wondering to what extent the Apollo magic relied on a high crossover frequency to the tweeter (or complete lack of crossover within its natural passband) and whether, by straying into lower crossover frequencies in a non-coaxial configuration this advantage is being threatened.
Well, I really liked the Apollo, but the Prometheus isn't for me. The widerange drivers are different: A is apparently a heavily treated European equivalent to the Celestion Blue guitar speaker, while the P is a somewhat-less-treated Eminence. I should also mention that I found both the A and P horn treble to be OK, but not great, and felt the same about the self-powered monopole subwoofer.

Long story short, the Apollo widerange driver has very special qualities - similar in important ways to the TT hempcone. By contrast, the Eminence has a much cruder, more "shouty" sound, and not to my taste.

It is a very good question how much "air" and dimensionality would be lost by crossing over to something as directional as a horn. My instincts tell me the Heil AMT would be the best sonic and dynamic match to the qualities of the big, powerful widerange driver. Unfortunately, the US-made AMT's have astoundingly bad quality control (6 dB sample-to-sample variation), and the Mundorf's are mighty expensive.

The most memorable qualities of the all-up top-of-the-line Linkwitz and Bastani systems are the stunning dynamics, freedom from boxy sound, and electrostat-like air and spatiality. MBL's get close, but the gross inefficiency means you lose the microdetails and vivid tone colors that come so easily in the Linkwitz and Bastani systems.

So part of the secret is efficiency, low IM distortion, and obviously no box coloration. Electrostats have no box coloration, low distortion too, somewhat more muted tone colors, but the dynamics are not even close. I don't like magnetic-planars at all, finding them opaque and lifeless sounding (very dim tone colors). I surmise high IM distortion due to nonuniform driving force over the diaphragm and a very low BL factor.

The reason I part company with the polar-response brigade is that I'm much more tolerant of blurriness in the mid driver working at the top of its range than I am tolerant of tweeter distortion at the bottom of its range. The HF distortion I find very unnatural and unmusical, gritty and harsh sounding, regrardless of the HF technology - horn, direct-radiator, etc.

Can an Azurahorn with the best compression driver sound as airy, open, and 3D as the best electrostat? I'm not sure of this. What about ribbons? They vary a lot, depending on build quality, and require serious thought about the crossover, since they are so intolerant of excess excursion.

This is uncharted territory for me, and I suspect for others as well. I don't think the answer is as simple as choice of crossover frequencies - it has to do with the inherent sonic character of the drivers themselves, and how well the sonic palettes of each technology blend together.

The greatest virtue of the large-area vintage-design guitar and state-of-the-art professional drivers are effortless dynamics and reach-out-and-touch-it realism, qualities that just aren't there in audiophile speakers. The challenge, which will probably take a lot of listening, is to find matching treble elements. I have seriously thought about small-area electrostats driving a large-throat Oris or Azurahorn.
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Old 2nd May 2007, 09:47 AM   #628
SunRa is offline SunRa  Romania
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That TT 12" alnico sure feels nice and measures well but that basket looks quite weird for a 200+ $. I guess the effects (like difractions) are more obvious in OB than in a stuffed and dampend monopole. I wonder if in case of a group buy they would make a custom basket more like in the 18sound style (see 15nd930, as someone here said, I guess a more opened basket than that you can't have.... well maybe the phy-hp ones)...
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Old 2nd May 2007, 10:29 AM   #629
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Lynn,

I think it's wise to stick to a path you know is likely to have a result you like. If you hear a pair of fantastic horns later on and you feel you're missing out you can do something about it later. Tracey and I may even end up back in Ft Collins in the next couple of years - you can come over and hear my horns!

I am curious to hear what music you use to audition speakers for particular problems. If you have a chance to list a few things that I would appreciate it. Although it isn't a lot of value to get second hand evaluations, if I could track down some of the pieces I would report back what I hear.

We do share a taste for BBC speakers. I've had 4 different pairs, including Spendor SP1/2s that are sitting idle on a shelf at the moment. I think it is a good sign that since I got the EQ dialled in on these horns I have not given the Spendors a single thought!

Jeff
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Old 2nd May 2007, 06:23 PM   #630
Variac is offline Variac  United States
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I think Lynnn REALLY wants a pair of TT's and what we have turned up in this discussion only reinforces that they could be a very good choice. Certainly it's essential that he check them out. The stamped steel basket is what guitar players like to see, so I suspect that's why it has them. If Lynn comes up with something great using them, and we order 50-100, I would suspect that we could get a custom DIY Audio version that has a cast basket and maybe a good price besides. It probably only requires them to spec this basket to their driver assembly guys who probabbly have them on hand BUT the unknown is the Alnico magnet- that might only work with the stamped basket, after all probably 99 percent of Alnico ordered is for guitar speakers. Their web site mentions that they are developing a neo magnet version. That might be a good option- Have to wait and see? Here's their Discussion forum:

http://www.online-discussion.com/ToneTubby/

More good stuff. They have a "dipped" version that goes higher.. hmmm

http://www.tonetubby.com/faq.htm

Scott is right I believe about the ribbons. The Founteks are now a aluminum/plastic film laminate, which appears to be much more durable and possibly better damped , but lose some livelyness. It is essential to not cross the ribbons too low, but with the TT that should be no problem..

After my experience with The Aurum Cantus, I would recommend these which are on sale:

http://www.partsexpress.com/pe/showd...number=276-410
They have the G1 also of course.
I have had no problems with reliability.

If they prove to be a good match to the TT tone, and in other ways, then Lynn could create an evolved version with RAAL ribbons, which are no doubt an upgrade.

My experience with a wide range open baffle mid has worked well for me and I recommend it.. There is a lot of appeal in having no crossovers in the critical range. I still think an open baffle might be the first thing to try- you can pick up a pair of solid core doors at a construction supply place with pretty veneer for less than $100 each, or get used ones for almost nothing... slap in the TT's and ribbons, and start experimenting.

To create dipole treble, you could use more of the same tweeter faced to the rear....or use something like the AC 2si at $60? Would it still be crossed over high enough to not be overstressed? Being about 3db less efficient, has about exactly the right output, without any padding.

http://www.partsexpress.com/pe/showd...number=276-400

The TT, Brown Soun headquarters are about 20 min. from my house, I should get on the bike and head that way sometime.
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