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Old 9th September 2012, 09:33 PM   #1
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Default Some BLH questions

Recently i have been reading several threads on full range drivers, especially horns. I like the idea of one speaker hooked directly to the amp. Ultimate KISS. I am a complete neophyte when it comes to speakers, but a few things don't make sense to me and i have a few questions.
On a back loaded horn, such as the Dallas, Sachiko, Vulcan, etc, how can the bass go through all those chambers and still get to the listener in phase with the rest of the music??
Does a large cabinet like a dual mouth horn increase the spl of any given driver??
Do back loaded horns require a BSC?? I read somewhere where the baffles in them act like notch filters. To me a bsc may not be exactly a xo, but it sure is made out of the same parts. They may in fact be wonderful, i just don't think they fit in with the single driver concept.
I read one thread on a Kirishima(SP) and someone said not to put them against a wall. Why not if the mouths are in the front?? Would a Vulcan type with the mouths in the rear be okay against a wall??
I like the looks of the horns, single and double mouth and have listened to a few of them on youtube( I know) and some sounded very nice. Most likely i will end up building a set with some larger full rangers. Probably 8" as i can't hear much above 12k, but can hear below 30. Just would like to get a few answers before i do. Thanks for any help. Regards, Jeff
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Old 9th September 2012, 11:11 PM   #2
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Just one BLH fan's opinion:

Quote:
On a back loaded horn... how can the bass go through all those chambers and still get to the listener in phase with the rest of the music??
It is delayed. Right off the bat, it's 180 degrees out of phase (let's say) because the horn output is coming off the back of the driver. So the trick is to live with or minimize the delay, but if possible, try to get it back in phase (e.g., delayed 360 degrees would put it back in phase, though still delayed).

Quote:
Does a large cabinet like a dual mouth horn increase the spl of any given driver??
Nope. It just brings the lower midrange and bass up to a matching SPL. So the otherwise "quiet" bass is now at roughly the right level (we hope).

Quote:
Do back loaded horns require a BSC??
The goal of the BLH is usually to eliminate the BSC but it depends how cleverly designed it is. You can optimize for very smooth midrange, or very deep bass, but (generally speaking) not both simultaneously.

Quote:
I read somewhere where the baffles in them act like notch filters.
If there is a spike in the driver's response at 2k, 5k, whatever frequency, it's not going away just because the back of the driver is fed through a horn. So a notch may still be beneficial, though not necessarily required (just listen 5 or 10 degrees off axis).

There are some truly amazing BLH's out there. Everthing involves trade-offs, though. For me, no one speaker ever does everything (no matter what), so you may need to adjust your musical tastes to what SET and single driver BLH's do well, at least for a few years. Enjoy!
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Old 9th September 2012, 11:27 PM   #3
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Don't think a full range is "simple". It can be just as challenging and require just as much complexity in networks as a multi-way. Add a horn and it can be quite a project. I may pick up a DEQ before I take on another full range.
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Old 9th September 2012, 11:58 PM   #4
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A BLH is a mechanical crossover and EQ, built in wood. So it has all the inherent problems of all other designs, just a different set of trade-offs. Some BLH's are excellent, and some are terrible. There is the -potential- for beautiful midrange purity, usually sacrificing some aspect of bass response.

But whether a notch is required is a function of the driver's midrange / treble response. Such a driver needing a notch would also need a notch in -any- cabinet, if the driver is radiating forward.
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Old 10th September 2012, 12:09 AM   #5
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Quote:
Originally Posted by rjbond3rd View Post
It is delayed. Right off the bat, it's 180 degrees out of phase (let's say) because the horn output is coming off the back of the driver.
To get a smooth transition between the direct radiation & that coming out of the mouth, the length of the horn and the low pass built into the horn need to coincide at an odd number of half wavelengths at the mechanical cross-over frequency.

The gain of the LF part of the output swamps the LF direct radiation.

Most people are fine with this, some small number of people are driven nuts by the time delayed bass.

dave
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Old 10th September 2012, 02:16 PM   #6
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Thanks fellas. Appreciate the knowledge. I think I'll go for it, probably doing one of the Fostex designs or maybe a Dallas first. Less material to ruin than a big dual mouth cabinet.

Dave?? Did you not design the Kirishima?? Would you have a frequency response for this box?? Would be interested to see it if you have one.

Again, thanks for all the help. I have built a few electronic projects but never a speaker and it seems the more i read the more confused I get. Regards, Jeff
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Old 10th September 2012, 04:58 PM   #7
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Dave?? Did you not design the Kirishima??
No. I just drew the plans (and put the website in place). As it says on the drawing, Designed by Scott Lindgren (aka Scottmoose)

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Old 10th September 2012, 08:13 PM   #8
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Okay, thanks Dave. I may have to rethink the size of the driver. There is a guy on youtube that played three different setups. Two fe103en and an fe126en. One of the 103s was in the fostex blh, the other in a zigmahornet, the 126 was in a blh designed for the 103. Playing the same female vocal in all three.

The 103 in the blh was very nice. Vocals were smooth and excellent. I was really surprised. Bass was a little weak, but what the hell, It's a 4" driver. Could always add a woofer.

Zigmahornet I didn't care for. Weak in every respect except the vocal. Vocal was nice but no dynamics and very little bass. Not near as good as the blh, to my ears.

The 126 was very good also and was the most dynamic of the three, which I suppose is to be expected as it was the largest driver. The bass was a but boomy, the vocals were very nice. I think in a different cabinet it would be the best of the bunch. The box was designed for the 103 and he just switched the driver.

Anyway, I think i could be happy with a much smaller driver than the 8". I was impressed by the 103 and the 126. If need be i think I would rather have a separate woofer to get the sweet vocals out of the smaller drivers. I listen to female blues and jazz singers a lot.

Thanks again for the input. Might have to hit up Scottmoose and have a chat with him. Regards, Jeff
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Old 10th September 2012, 08:28 PM   #9
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Quote:
Originally Posted by jdsackett View Post
youtube that played three different setups.
Jeff,

Any attempt to evaluate something by listening off youTube is useless. Heavy compression and what you hear is filtered thru the system you are listening thru

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Old 10th September 2012, 08:48 PM   #10
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Agreed, but it does give some idea if you have never heard them before. I listened to them through the speakers on my laptop, so I know exactly what you mean. Not Exactly hifi, lol. Regards, Jeff
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