Sorry, doesn't work that way, the larger the horn, the lower in frequency/'stronger' the reflections back to the throat 🙁, so a higher and/or steeper XO is required to weaken them. That, or add a foam 'plate' gasket similar in concept to the one used on the Altec M19 or horn extension like me and a few others have done to create a diffuse terminated mouth. In retrospect, this option is probably should only be used where the horn is set back from the front of the cab.
The problem here of course is figuring out what the density needs to be and lacking time/patience back when I was experimenting I went with open cell 'trail pad' I found in the local K-Mart's Sporting Goods section for what I figured was overkill for stacked 511s/500 Hz, but it didn't sound muted to me and the women folk liked its smoothed over HF, so maybe not.
GM
Kolbrek finds that LeCleach cut short (at 90 degrees)(also with tractrix being similar) affects more than just the low end. Here is the link. Lots of sim results to sift through.
Yep, guess I should have added that the lower in frequency, the wider an eigenmode's [reflection's] bandwidth [BW].
GM
GM
OK, thanks Greg and Allen.
I'll run the mic over the horns when finished...then see where we get to. I can go LR3 xover design if needed (likely).
I'll run the mic over the horns when finished...then see where we get to. I can go LR3 xover design if needed (likely).
Darned if i know!
Picked up a 25lb or was it 50lb bag almost 10 years back for a project...
... I'd check with the pottery supply shops, the ones that supply the shops that sell retail, they have a wide variety of compounds with different characteristics. They have different consistencies when mixed up. The one I got is pretty much like thin pancake batter. Same sort of color. But they have stuff that is thick and globby too... best look around and see what is what. The key is strength when cured. Some of the stuff is kiln fire only. That would mess up all that careful work on the horns! </joke>
This stuff is more hard than concrete - so that's a criteria.
Also they make stuff for patching roadways, bridges in particular that is very similar, it probably has other additives, but if you can find that, that would work too...
This stuff was for poured molds... but you'd have to choose amongst the things you can find. (working with poured stuff is tricky, btw)
Picked up a 25lb or was it 50lb bag almost 10 years back for a project...
... I'd check with the pottery supply shops, the ones that supply the shops that sell retail, they have a wide variety of compounds with different characteristics. They have different consistencies when mixed up. The one I got is pretty much like thin pancake batter. Same sort of color. But they have stuff that is thick and globby too... best look around and see what is what. The key is strength when cured. Some of the stuff is kiln fire only. That would mess up all that careful work on the horns! </joke>
This stuff is more hard than concrete - so that's a criteria.
Also they make stuff for patching roadways, bridges in particular that is very similar, it probably has other additives, but if you can find that, that would work too...
This stuff was for poured molds... but you'd have to choose amongst the things you can find. (working with poured stuff is tricky, btw)
FWIW, I bonded cement backer board to the big 1803 size WG's I made to replace the stacked 511s. Don't know if they were as heavy as a tar filled one, but were sure plenty heavy and sounded super dull when struck with a ball peen hammer, so resonated well below its passband. Not pretty of course, but the system was always behind a room height screen, so cometics be d@#$%&! 😀
If it had been a requirement, then a thin 'skin' of marine grade flexy ply could be added.
GM
If it had been a requirement, then a thin 'skin' of marine grade flexy ply could be added.
GM
Thanks GM. How would you describe the use of a large horn like the 1803 in a domestic setting, vs 8 or 12 multicell or other smaller Altec? In other words, why did you choose this horn for your room? Kindly
More gluing today. All 4 'halves' now prepared. Tomorrow I will start painting insides. Next weekend I collect the 290's.
More gluing today. All 4 'halves' now prepared. Tomorrow I will start painting insides. Next weekend I collect the 290's.
Attachments
Cool project! Thanks for sharing.
Looking forward to reading what you get out of them. I've had a hard time getting 290 drivers all they way down to 300Hz. Maybe your big mouth horns will do it.
Looking forward to reading what you get out of them. I've had a hard time getting 290 drivers all they way down to 300Hz. Maybe your big mouth horns will do it.
As WE proved, even a 1" throat driver can do mid-bass at high SPL if the horn's big enough. If memory serves [debatable nowadays], it takes a ~192 Hz flare frequency to do 300 Hz with authority, though for a HIFI app/4th order it can be up around ~243 Hz with these phenolic loaded 'bad boys'.
GM
GM
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You're welcome!
What can I say? 'BIB' rules in acoustics and the more of the human vocals BW a horn can control without reflecting off any boundaries between it and the audience, the better.
Since I knew basically nothing about conical horn design at the time other than megaphones sounded horrible and conical tapered motor induction 'horns' didn't perform as well as flared ones and noting that the tar filled's physical dimensions looked very close to some of Harry Olson's conical horn drawings, I used it as a guide to 'prove' his assertions that it would have a smoother, more tonally balanced, uniform polar response with the trade-off of lower efficiency compared to the rising on axis horns required for max efficiency.
Once exposed to these wave-guides [WG] there was no going back for me except for when coupling to period correct matching impedance electronics or when peak SPL was the goal, though knowing what I do now WRT horn/WG design, I'd use them instead [Synergy concept] for peak SPL too.
Note that these simple WGs needed the foam 'horn' treatment too since this was many years before I experimented with the large end corrections required to further improve its overall performance without sacrificing any efficiency and/or compensate by increasing the XO point.
GM
I call it the "mad dog horn" because of the foam at the mouth. 😀 Works like a charm.
I used the 290s on an Altec 803 horn and felt that 300Hz was a stretch. 500 Hz was more comfortable. With some EQ and a 4th order high pass, sure, 300Hz could work.
Here is my advice. Forget where you want to cross over, cross it where it works the best. That is not easy advice to follow, but I've found the results to be best.
I used the 290s on an Altec 803 horn and felt that 300Hz was a stretch. 500 Hz was more comfortable. With some EQ and a 4th order high pass, sure, 300Hz could work.
Here is my advice. Forget where you want to cross over, cross it where it works the best. That is not easy advice to follow, but I've found the results to be best.
Oh yeah, for sure, the 803 as big as it is too small for high efficiency and why dual drivers is required to use them at 300 Hz, though selve it down to a woofer's efficiency on a wide baffled cab and a single works fine.
Agreed, unless properly designed for a specific XO point/slope, etc., from the get-go then it's what works best overall in the intended app and it is what it is.
GM
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Thanks GM, Pano
I agree SQ is the ultimate authority, not theoretical targets.
The reason I chose 300, is because of goal to get CD performance in that range. Most/all other systems have cd from 500, unless using WE SATO style horns. I've had Azura, Yuichi Altec and other horns, all 500 hz min, hence this special project.
I agree SQ is the ultimate authority, not theoretical targets.
The reason I chose 300, is because of goal to get CD performance in that range. Most/all other systems have cd from 500, unless using WE SATO style horns. I've had Azura, Yuichi Altec and other horns, all 500 hz min, hence this special project.
Fingers crossed that it works out. A solid 300Hz needs a big horn. Measure and listen to sweep in that area. You'll hear the distortion on sine waves if it's there.
I run the 350hz round tractrix with the JBL 2441 and it does not work well below 700hz....to my ear.
You're welcome!
Djn just reminded me how much [lack of] attention I've paid to the thread as a whole, just 'knee jerking' some responses to specific issues.
Tractrix don't start loading until a 1/2 octave away and one octave to 'get up on the pipe' [properly load a driver], so 400 Hz is probably the best it will do, though once shelved to HIFI SPLs maybe 350 Hz. 'Hope springs eternal' 😉
WRT low end distortion, one 'trick' is that these normally came with a loading cap, so removing it and damping the rear cover real good will help same as with the 1" format drivers and if you want to experiment; then based solely on hearing tests I got some pretty impressive improvements by swapping the rear covers for stuffed TLs on a pair of 802Ds way back when.
Reduces power handling of course, but gives a much lower Qt roll off slope Vs the normal peak, then 'falls off a cliff' response [1.2 or 1.4 Qt?] that demands an XO point somewhat above its sealed cab Fb, though no clue if it will get you to 300 Hz.
FWIW though, it did help smooth out the low end of the big ~conical WGs, so recommend using a familiar female or two's 'sotto voce' recording [young daughter and naturally soft spoken Southern Belle wife in my case] to determine if it was 'live or Memorex' 😉 to 'ape' a popular ad at the time.
GM
Ok...
the problem with multicells WRT in home use is that they were and are intended to be used in auditoriums, for wide horizontal dispersion. An 1803 using in anything less than a barn sized room is NG if used with the width being horizontal. Won't image worth a darn, and too much stuff banging off the walls.
I have used a 1003 sucessfully, it sounds better than an 803, mostly due to the greater mouth area. BOTH of them work far better if the horns are A) aimed to "toe in" such that the focus is a point before at or just behind the center listening position, and B) they are run with the width of the horn vertical!!
Depending on the nature of the floor and the nature and height of the ceiling, you will need to do something to "taper" the HF. One does not want to beam much of anything above 5kHz to a ceiling that is maybe 7-10ft high, nor does one want to beam that same energy onto a hard floor. The solution is to stuff the throat area of the cells that aim in those directions with something that sufficiently attenuates that >5kHz energy so as to not cause a false up/down image... that is usually a fluffed out single cotton ball (once a standard cotton ball, now known as a "jumbo" in the USA) stuffed into the throat area of the cells in question, to the point where it can just sit there... works like a charm. 😀
Now, I have measured the 803, 1003 and 203. Both the 1003 and the 203 will go flat below 300Hz, usually around 275Hz... the 803 a slight bit higher. This is HIGHLY dependent upon the driver used. The Altec offerings, frankly, are designed to NOT go down that low. While it is highly flawed in other ways I think that oft mentioned Atlas driver, the one that Klipsh originally used on their larger mid horns for the K-Horn system have a good shot at going low, as they are essentially a WE555 geometry with a phenolic diaphragm. The limiting factor on all of these drivers is the suspension of the diaphragm, notwithstanding any Xmax limits that may form a practical SPL limit at LFs.
So, for home use, horizontal in a "normal room" - awful.
For home use, vertical & frequency "tapered" - amazingly great with the appropriate driver. (usually not an Altec, imo).
(PS, used this way they resemble a tapered short vertical array, with a curved face) </heresy>
the problem with multicells WRT in home use is that they were and are intended to be used in auditoriums, for wide horizontal dispersion. An 1803 using in anything less than a barn sized room is NG if used with the width being horizontal. Won't image worth a darn, and too much stuff banging off the walls.
I have used a 1003 sucessfully, it sounds better than an 803, mostly due to the greater mouth area. BOTH of them work far better if the horns are A) aimed to "toe in" such that the focus is a point before at or just behind the center listening position, and B) they are run with the width of the horn vertical!!
Depending on the nature of the floor and the nature and height of the ceiling, you will need to do something to "taper" the HF. One does not want to beam much of anything above 5kHz to a ceiling that is maybe 7-10ft high, nor does one want to beam that same energy onto a hard floor. The solution is to stuff the throat area of the cells that aim in those directions with something that sufficiently attenuates that >5kHz energy so as to not cause a false up/down image... that is usually a fluffed out single cotton ball (once a standard cotton ball, now known as a "jumbo" in the USA) stuffed into the throat area of the cells in question, to the point where it can just sit there... works like a charm. 😀
Now, I have measured the 803, 1003 and 203. Both the 1003 and the 203 will go flat below 300Hz, usually around 275Hz... the 803 a slight bit higher. This is HIGHLY dependent upon the driver used. The Altec offerings, frankly, are designed to NOT go down that low. While it is highly flawed in other ways I think that oft mentioned Atlas driver, the one that Klipsh originally used on their larger mid horns for the K-Horn system have a good shot at going low, as they are essentially a WE555 geometry with a phenolic diaphragm. The limiting factor on all of these drivers is the suspension of the diaphragm, notwithstanding any Xmax limits that may form a practical SPL limit at LFs.
So, for home use, horizontal in a "normal room" - awful.
For home use, vertical & frequency "tapered" - amazingly great with the appropriate driver. (usually not an Altec, imo).
(PS, used this way they resemble a tapered short vertical array, with a curved face) </heresy>
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OK, thanks again guys, GM, Bear.
For starters, I'll use MiniDSP, so I can add eq anywhere to see if it sounds good with 300hz.
I understand the horn's Fs has a part to play...and the tractrix profile that Bear talks about.
At the end of the day, I'll get near 300, maybe 350....which will be a great outcome.
I want to beat Avant Garde (Trio) at their onw game, but not having to use a paper driver in the large horn.
If this 200Hz DIY model doesn't work, I'll buy an Azura 160Hz model, with 1.0meter diameter mouth, and 90cm deep....all the way to 1.4 inch throat. That should do the trick.
For starters, I'll use MiniDSP, so I can add eq anywhere to see if it sounds good with 300hz.
I understand the horn's Fs has a part to play...and the tractrix profile that Bear talks about.
At the end of the day, I'll get near 300, maybe 350....which will be a great outcome.
I want to beat Avant Garde (Trio) at their onw game, but not having to use a paper driver in the large horn.
If this 200Hz DIY model doesn't work, I'll buy an Azura 160Hz model, with 1.0meter diameter mouth, and 90cm deep....all the way to 1.4 inch throat. That should do the trick.
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