The same professional audio community that builds and sells the infamous 8" woofer + 1" tweeter combo?
What horns did you listen to that gave you this impression, the friend who has the axi2050 on a 250hz JMLC sees things completely different from you and had this to say
Or did we forget that the ribbom tweeters are just as beaming as horns, yet people sure do love the tpl150H in particular, the holy grail of commercially available amt tweeters pretty much.
We are arguing opinions, and I welcome them all, you may bring me to the light, but not without me playing devils advocate.
The half length of 200hz is ~33".....the ka1 for a 15" woofer is 286hz.....xo the horn at 286 I see no problems with those polars, the Ka2.2 for the horn is ~286hz....So having the HF with a 2.2 and woofer crossing at a ka1....is a problem?
Good point GM, with that thought in mind, a 33" horn on top of an enclosure housing a 15" woofer and a 33" front baffle....thats going to be a successful pairing in directivity (ka2.2 at 286hz...even better ka if the xo is dropped to 200hz), given the proper xover which is allowable by such an extended range of the axi2050 or similar driver
If I am wrong I'll be corrected....I'd be more interested in whether or not the horn can support the low side of an axi2050, loading wise, it has been said, that loading is not an issue for home use.....unless trying to extend the functional range of the driver...... but the Axi2050 plays to 300hz within spec so 200hz isn't a crazy stretch but rather lets look at some data from the axi2050 and jbl 250hz....an article presented earlier suggest that a horn will have exaggerated group delay towards its unusable range...but maybe in this situation its the fact that the driver is just capable without horn assistance...just look at the data.
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Well, we're always trading efficiency for BW, so in theory we can trade ~20 dB of peak power handling for a 20 - 20 kHz BW and ~10 dB for 100 - 20kHz given a sufficiently large horn based on its PWT specs and of course CD horn EQ to flatten it; so, is there enough peak power handling left?
GM
GM
About that extended range, for starters the transition from eighth space to full space is going to cost, and expanding horns lose their directivity earlier for a given size.
It has also been mentioned that expanding horns create low frequency limits, rather than the other way around.
I also think you could do better than to view LeCleach horns as a conventional, end to end device. This is a different animal. Bjorn Kolbrek did some simulations which are interesting. Hornresp is helpful.
It has also been mentioned that expanding horns create low frequency limits, rather than the other way around.
I also think you could do better than to view LeCleach horns as a conventional, end to end device. This is a different animal. Bjorn Kolbrek did some simulations which are interesting. Hornresp is helpful.
I wonder how low in frequency the Axi2050 can maintain SPL, even in an ideally matched horn? The Celestion measurement into the SEOS-30 (Minimal frequency from 300 Hz), shows SPL drops under 600Hz.
The drop is due to the SEOS-30, which doesn't provide much loading below 600Hz.
You'd probably get away with using the driver from 400Hz behind the SEOS, but 600Hz is about the minimum loading frequency of this 90x60° waveguide.
I am pretty sure that even with a hypothetical SEOS-100 you won't see a huge difference in the plot.
Only a very narrow OS waveguide, for example 30x30°, would (probably) load the driver at a lower frequency. That horn should also be quite deep.
Something like this:
You'd probably get away with using the driver from 400Hz behind the SEOS, but 600Hz is about the minimum loading frequency of this 90x60° waveguide.
I am pretty sure that even with a hypothetical SEOS-100 you won't see a huge difference in the plot.
Only a very narrow OS waveguide, for example 30x30°, would (probably) load the driver at a lower frequency. That horn should also be quite deep.
Something like this:
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Based on this and GM’s comment about headroom, you can theoretically run 200hz on a ~200hz jmlc...the group delay is right even slightly below 200 and I think there is enough head room, I’ll have to make sure then downside is that decay is up, around 200hz ( I’ll post that later) maybe not to its detriment but still....distortion is under 1%......I’m waiting to get more details from my guy with the actual hardware, the ears are the final say so.
I’ve also read that the throat depth is the spec that limits loading so once again, at a half wave length things should be optimal. It should be noted that even though we see half and quarter wavelength in practice it’s actually the whole wave length size that is considered as best practice.
I plan on making my own horn this winter, so I’m picturing a throat depth at half wave length and a mouth diameter at whatever I can decipher as preferable. Whether it’s 15” to match the woofer polar more closely or larger in order to bring directivity down range....
Yes, but an acoustical 1/2 WL requires a 1WL [or more] long horn depending on both flare and frequency factor, so that 33" ain't going to cut it and all this assumes a full size mouth, which with a low diffraction rollover is going to be around 5.4 ft in diameter or ~ a 210 Hz 1WL horn/woofer ctc spacing, putting you back to a MTM alignment.
When it comes to trying to work around the iron law, 'the more things change, the more they remain the same'.
GM
GM, In this thread and other you said about the 'gold standard' Vas/1.44 = net V. I did some searching but I can find the root of the idea/theory/book behind it.
Any links or terms I could use to search regarding sizing of bass cabs.
thanks
EDIT: you never called it 'gold standard' but I couldnt think of something appropriate
Can you use more words?
My research says that the horn length should be 1wl in length, The wavelength being the lowest intended note to produce. Which 200 is 67". Thats where my knowledge stops
lets look at some real world application, as we are discussing best practice, lets see what can work, even though the horn is not of "best practice" for the extension intended, what does the data show. I see super tight group delay down to ~120hz, THD is 0.717% at 200hz, and the decay can be seen in the graph but I'm not able to translate this into real world expectations, looks ok to me though.....and the drop off is likely due an active crossover, so if that turns out to be true (haven't heard from the guy yet) that is a factor to consider.
The horn is a 250hz JMLC with a 65cm diameter mouth and ~15" length depth....so with a bigger horn the extension should improve in performance, but this may already be in the passing range or am I crazy?
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One of the posts: Full Range Build, 12" driver...
I was told it during my Altec Plant visit in '68 and AFAIK is only mentioned on pg. 76 of this book by two Altec engineers and even then a bit 'cryptic' to the casual DIYer, especially before T/S: How To Build Speaker Enclosures By Alexix Badmaieff & Don Davis : Free Download, Borrow, and Streaming : Internet Archive
As for other 'golden'
reflex alignments, there's a few, but nobody uses them since T/S designer programs became widely available. A couple of exceptions I never see mentioned around here anymore is WP's Pi Align, a great prosound, corner loaded or just all around high SQ alignment that AFAIK he still uses for his kits/builds and Keele's? extended bass shelf [EBS] alignment [AKA Altec's X-Bass]. Note that the 'PiAlign' link auto downloads a zip file with some old driver specs, some stuff I don't remember and an .exe program to calculate it: Pi Speaker Forum - Various alignments - Wayne Parham, August 22, 2002 at 23:03:47
EBS/X-bass design routine: Calculating an EBS alignment
All that said, regardless of the alignment or how much damping used in the cab, it's always a good plan to critically damp the vent using an impulse test to get that last [little] bit of any cab/vent resonances for best overall SQ/lowest practical group delay.
GM
Is the "very large volume alignment" (oversized cab) another take on the EBS?
The notion of "very large volume" depends on the THIELE and SMALL parameters.
The volume setting is VAS * Qts² . It is expressed in liters if VAS is also in liters.
The volume of the speaker is expressed in the form VB = N * VAS * Qts² .
A typical bass-reflex speaker uses a volume calculated with N between 2 and 16, and most often below 8.
A very large volume bass-reflex speaker uses a volume calculated with N greater than 16, and up to 45.
If we take an average N of 5.6 for a typical bass-reflex speaker, and an average N of 32 for a very large volume bass-reflex speaker,
a very large bass-reflex speaker is 6 times larger than the usual bass-reflex speaker.
This is an example:
The notion of "very large volume" depends on the THIELE and SMALL parameters.
The volume setting is VAS * Qts² . It is expressed in liters if VAS is also in liters.
The volume of the speaker is expressed in the form VB = N * VAS * Qts² .
A typical bass-reflex speaker uses a volume calculated with N between 2 and 16, and most often below 8.
A very large volume bass-reflex speaker uses a volume calculated with N greater than 16, and up to 45.
If we take an average N of 5.6 for a typical bass-reflex speaker, and an average N of 32 for a very large volume bass-reflex speaker,
a very large bass-reflex speaker is 6 times larger than the usual bass-reflex speaker.
This is an example:
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Don't recall ever seeing this one, but it has the 'shelf', so works for me.
GM
You're welcome!
I wanted to learn horn, TL speaker design theory so I could design high performance [HP] intake/exhaust systems and owe all my early education from another Don Davis that I thought was him in this NACA study, but no relation:
https://digital.library.unt.edu/ark:/67531/metadc60567/m2/1/high_res_d/19930092208.pdf
GM
The Don Davis, former vice president of Altec, was also the founder of SynAudCon.
I came across this article, in which (I suppose) you were mentioned in relation to the TL design.
I came across this article, in which (I suppose) you were mentioned in relation to the TL design.
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