I'm curious as to what voltage would be required to hit 100 dB at 30 Hz at your listening seat, measuring your modified A7/5's fundamental, not harmonics.
This http://www.diyaudio.com/forums/pass-labs/168040-f5-2sk2013-2sj313-13.html#post2418636 is my - very personal - version of Altec VOTT.
I like the fast (very light cone) woofer, the only issue is the limited maximum admitted power. However, with a good (well-damped) class-A (Pass' F4, F5 or alike) the lack of bass is negligible, and the pleasure maximum.
And yes, the horn is all but well damped, (if striked it rings like a bell), but the sound is sweet.
If I would build today a similar system, I'll be curious to try these drivers B&C SPEAKERS (in fact, I had the opportunity to listen to them in a commercial product, and they are really amazing).
Anyway, I'm very happy to listen to my little Altec babies (that are as old as me
)
Guido
I like the fast (very light cone) woofer, the only issue is the limited maximum admitted power. However, with a good (well-damped) class-A (Pass' F4, F5 or alike) the lack of bass is negligible, and the pleasure maximum.
And yes, the horn is all but well damped, (if striked it rings like a bell), but the sound is sweet.
If I would build today a similar system, I'll be curious to try these drivers B&C SPEAKERS (in fact, I had the opportunity to listen to them in a commercial product, and they are really amazing).
Anyway, I'm very happy to listen to my little Altec babies (that are as old as me
)Guido
Originally Posted by weltersys
I'm curious as to what voltage would be required to hit 100 dB at 30 Hz at your listening seat, measuring your modified A7/5's fundamental, not harmonics.
Such a huge cabinet for so little low frequency.
I'm curious as to what voltage would be required to hit 100 dB at 30 Hz at your listening seat, measuring your modified A7/5's fundamental, not harmonics.
Yeah, looking at Tom's before and after graphs, looks like the stock A7 rolls off around 120 Hz, and the "after" rolls off from 60 Hz.
Such a huge cabinet for so little low frequency.
Attachments
Yeah, it's a crazy big box not to go down lower. Tom's graph looks about like what I got with the original ports. After some work there and I'm down to the mid 40s. I "think" there's another ~10Hz to squeeze out if the ports are right. More work to do.
The trade off for me is the naturalness of the sound. It's a box that does not sound like a box - it sounds like real acoustic instruments. And that's what I like.
The trade off for me is the naturalness of the sound. It's a box that does not sound like a box - it sounds like real acoustic instruments. And that's what I like.
i run altec 9864 cabinets in my livingroom. they are biamped. i use a dbx 2 way electronic crossover and drive the cabinets with Mc tube amps. i would call these a coaxial version of the VOTT idea.
i love them. yes, they are not the most accurate. they also dont come alive until played loud. the cool thing is loud comes easily. 20wpc and you are having a party. when i first brought them home i took a bare ended headphone cable and used a single AA battery driven minidisc player to drive the speakers loud enough to hear the music in a room. the size of the cabinets is part of the efficiency.
AFAIC for vocals, brass, and guitar nothing beats horns.
info on these speakers can be found here..
http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/9864-8A Speaker System.pdf
i love them. yes, they are not the most accurate. they also dont come alive until played loud. the cool thing is loud comes easily. 20wpc and you are having a party. when i first brought them home i took a bare ended headphone cable and used a single AA battery driven minidisc player to drive the speakers loud enough to hear the music in a room. the size of the cabinets is part of the efficiency.
AFAIC for vocals, brass, and guitar nothing beats horns.
info on these speakers can be found here..
http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/9864-8A Speaker System.pdf
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I don't have the room for these kinds of systems but I can certainly see the appeal.
I'm involved in professional theater design and install these days. The A7s and such that you guys like are just the cinema systems of a particular era. Pull out the articles by Shearer or Hilliard going back to the 30s and read the history. It is facinating and highlights where real loudspeaker science had its orrigins.
The modern trend has been that big power is cheap so horn loaded LF is just not used any more. A pair of 15s in a large cabinet will give you much wider bandwidth and smoother response. The upper bass efficiency kick and higher directivity of a short horn doesn't buy much in a domestic environment.
Don Keele shows the comparison between folded bass horns of reasonable size (a W bin) and 2 or 4 15" woofers.
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1976-05 AES Preprint) - Efficiency, Horns vs DR.pdf
What I typically install in a mid size theater would be from the JBL 4675 family.
JBL :: Product
http://www.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=634
Drivers are smooth and the directivity is very even so a little bit of EQ gives great response and coverage over the seating area.
My advice: a pair of 15s in a good vented box and then find your favorite horn and driver. Electronic crossover and good EQ and you are set.
David
A horn system does have it impuls behavior and directivity that a isn't the same a BR or Onken.
Here the modern BR-layout idea for passive approach. Acive would be compact closedbox low with enough power to get the same spl and dsp technology to correct low response down to 20Hz.
http://www.diyaudio.com/forums/multi-way/201876-first-diy-project.html#post2807789
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Yep. The A7 was Altec's small speaker for small cinemas. Sure were a lot installed. At an audio show I met a guy who had pulled more than 20 of them out of an old multi-pex in Arizona. He sold them off slowly and paid of his house.
Have you worked with the new 3000 and 4000 series? The ones wit the horn loaded 6" mid? (3730, 3731) I'm curious about those.
I do like twin 15 cabs a lot. Thought about building one, as I have 4x Altec 416-8A.
Keep in mind that one could tune the A-7 to have any desired cutoff (assuming the right driver was also available) BUT the system sensitivity is set by the cabinet volume and low corner F. Just like at the top end, if one wants flat response and has wide dispersion, then the HF corner will be what limits the sensitivity.
Theaters are very cost sensitive and that shows in many theater’s sound quality. That is also why some A-7’s that were installed a lifetime ago are still in use.
We supply some cabinets to some high end theaters, ones where the size or sound requires something more. This is one of the theaters; it is the Museum of Science and Industry in Chicago. It had been an Omni-max theater, a 5 story tall sphere but has now been converted to an IMAX.
The speakers are SH-96’s and four TH-50 subwoofers.
How does it sound relative to the JBL’s normally used? Post #41 here mentions that.
IMAX cinema sound - Page 3
Danley Sound Labs | Portfolio
http://www.danleysoundlabs.com/pdf/SH 96 spec sheet.pdf
The advantage of these over the normal way of separate sources and horns is that there is only one source, no lobes or nulls, the entire front of the cabinet is usually the mouth so the pattern loss F is as low as possible.
On the other hand, having all the drivers loading one horn, makes the package a lot smaller. Consider (relative to the old way) the SH-96 has four 15” woofers, 6, mid horn drivers and one 1.4 inch hf compression driver.
There was a side by side listening event at a trade show recently.
Each mfr supplied a system capable of reaching the desired SPL at 10 meters and the show people played the same rack through each system at the same loudness. We sent an SH-96 (like the ones above) and one TH-118 which was by far the smallest and least costly system.
If you have headphones, you can hear what each of the systems sounded like in the video below. I would have liked to bump up the warmth in the voice range in ours but they were making a point about having NO eq applied
Nov 14, 2011 7:04am | Facebook
Best,
Tom
Theaters are very cost sensitive and that shows in many theater’s sound quality. That is also why some A-7’s that were installed a lifetime ago are still in use.
We supply some cabinets to some high end theaters, ones where the size or sound requires something more. This is one of the theaters; it is the Museum of Science and Industry in Chicago. It had been an Omni-max theater, a 5 story tall sphere but has now been converted to an IMAX.
The speakers are SH-96’s and four TH-50 subwoofers.
How does it sound relative to the JBL’s normally used? Post #41 here mentions that.
IMAX cinema sound - Page 3
Danley Sound Labs | Portfolio
http://www.danleysoundlabs.com/pdf/SH 96 spec sheet.pdf
The advantage of these over the normal way of separate sources and horns is that there is only one source, no lobes or nulls, the entire front of the cabinet is usually the mouth so the pattern loss F is as low as possible.
On the other hand, having all the drivers loading one horn, makes the package a lot smaller. Consider (relative to the old way) the SH-96 has four 15” woofers, 6, mid horn drivers and one 1.4 inch hf compression driver.
There was a side by side listening event at a trade show recently.
Each mfr supplied a system capable of reaching the desired SPL at 10 meters and the show people played the same rack through each system at the same loudness. We sent an SH-96 (like the ones above) and one TH-118 which was by far the smallest and least costly system.
If you have headphones, you can hear what each of the systems sounded like in the video below. I would have liked to bump up the warmth in the voice range in ours but they were making a point about having NO eq applied
Nov 14, 2011 7:04am | Facebook
Best,
Tom
I totally agree, it's the magic of Altecs
Isn't that true? Measurements and graphs be damned I say. There's just something special that happens to a woofer, almost any woofer, when you slide it into and 825/828 cabinet.
tmblack, I didn't like the PartsExpress waveguide combined with the 806A drivers I have, compared to the 811B. That said, I made modified mounting plates for the 2-bolt mounting system that the Altec 1"drivers use, to mate the driver to the waveguide, and I didn't work very hard to make the throat perfectly smooth, etc. So whatever harshness I was hearing from the waveguide system might have been related to that. Also, Geddes' waveguide concept depends upon open-cell foam mounted like a trumpet mute inside the waveguide, to cancel standing waves across the profile of the waveguide - supposedly this makes a big difference in smooth HF response. I did not do that - I just went back to the 811B and said, "Aaaaahhhh . . . . "
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