is it possible to cleanly cover 100 - 600 hz with an FLH that has approx a 26"w x 24"h mouth and less than 30" depth?
I'm running this in conjunction with Yuichi A290 clones and B&C DCX50 coax drivers, so its being designed for higher end home audio use.
Midbass driver is the B&C12MH32, which should be a good choice for this purpose based on TS data and specs. I already have this driver on hand.
Looking on the web, I see some designs by Edgar with his System 100 horn using a 15" JBL. Also some other designs which are far too big to fit where I need this to go, specifically being able to physically time align the whole thing. The Inlow designs are nice, but again too deep. I understand there will be tradeoffs with truncated flares. Hopefully there is an existing design out there which is close to what I'm looking for.
I'm not that experienced with midbass horn design from scratch. Other than repurposing existing designs by modifying the throat or rear chamber, its not something I'd tackle. I've used Hornresp to explore some other bass horn designs, but currently don't have access to it due to ongoing PC issues. If someone experienced in this area could maybe plug in a few numbers and point me in the right direction, I'd greatly appreciate it.
I'm running this in conjunction with Yuichi A290 clones and B&C DCX50 coax drivers, so its being designed for higher end home audio use.
Midbass driver is the B&C12MH32, which should be a good choice for this purpose based on TS data and specs. I already have this driver on hand.
Looking on the web, I see some designs by Edgar with his System 100 horn using a 15" JBL. Also some other designs which are far too big to fit where I need this to go, specifically being able to physically time align the whole thing. The Inlow designs are nice, but again too deep. I understand there will be tradeoffs with truncated flares. Hopefully there is an existing design out there which is close to what I'm looking for.
I'm not that experienced with midbass horn design from scratch. Other than repurposing existing designs by modifying the throat or rear chamber, its not something I'd tackle. I've used Hornresp to explore some other bass horn designs, but currently don't have access to it due to ongoing PC issues. If someone experienced in this area could maybe plug in a few numbers and point me in the right direction, I'd greatly appreciate it.
Attachments
That design is too deep with that small throat. The 8PE21 is a good driver, but it likey won't go as low or loud as the 12MH32 - it has to keep up with 2 x 18s down low.
hmm the length seems a bit short for 100Hz especialy if it has to include the driver chamber, my 100Hz midbass is 1.2m long. 600Hz may also be a challenge without a phase plug. Here is my horn: https://www.diyaudio.com/community/threads/mega-midbass-straight-horn-139db.349105/
I agree about the length. Thats the big challenge. I know the horn profile can be folded, but that isn't as easy to do with a higher upper cutoff point. 600 hz is pretty high for a 12" driver in a horn and I'm right at the limit with my driver choice. I could use a pair of 8PE21s instead, but their may be phase cancelation issues with more drivers in one horn higher up off axis, so the power response will suffer. I want the controlled directivity of a midbass horn, which is why im trying to implement a horn instead of a direct radiating bass mid. The efficiency is also lower and there are some other drawbacks ie physical time alignment.
In that case you can work out your profile in reverse based on the directivity you set. The size and the loading will come from this.
You can also increase the horn length through an exponential throat section before the conic-conic directivity controlling portion of the horn, it will mean that the horn will start to beam at a lower frequency but this is unlikely to be of concen at 600Hz with your given dimensions. Fabricating a dual driver exponential horn throat is what I am doing at the moment, the hard part is actualy generating the 3D shapes for me as I have had to work through lots of issues. Check out this video for a novel idea on reducing the depth and combining two drivers:
Using the rear chambers inverted ie megaphone style, is a efficient way of using space and creating phase plugs in a sense. I would try to avoid asymmetry and sharp bends to maintain uniform wave front.
I also believe the horn can be effectively shortened with multiple drivers due to the increase of throat area shortening the effective profile. This also changes the alpha ratio and depending on using 1/4 or 1/2 pi mouth, which also should theoretically shorten the total length. Using two 12s located in the side cavities of the horn may be a more practical way of increasing the flare and avoiding sharp bends. Efficiency on the bottom will also go up with 2 drivers. Any more extension below 100hz will be a bonus and allow for better integration.
I also believe the horn can be effectively shortened with multiple drivers due to the increase of throat area shortening the effective profile. This also changes the alpha ratio and depending on using 1/4 or 1/2 pi mouth, which also should theoretically shorten the total length. Using two 12s located in the side cavities of the horn may be a more practical way of increasing the flare and avoiding sharp bends. Efficiency on the bottom will also go up with 2 drivers. Any more extension below 100hz will be a bonus and allow for better integration.
What worries me is the relatively small throat area I come up with on these 12MH32s, roughly 22 sq.in. Thats going to provoke issues with the front chamber and make it sensitive to throat geometry, which also complicates the overall flare design, especially if I fold the flare up with 2 drivers.
How do you know the throat chambee volume isn't going to do things undesirable? IOW how critical is it to get that volume right to achieve desired response? i thought that was an interactive thing with the throat area in defining top end rolloff? Is it not that critical?
Depends on the model you are using, if using a t/s parameter lumped element model it forms a low pass pole but also it has acoustic size so you also have additional acoustic cancelation due to path length differences not modeled unless you do a FEM sim. If you look at my thread you will see the rolloff starts earlier than the lumped element sims predict due to this effect. Both can be mitigated with a correctly designed phase plug but you have additional poles caused by the things like the mass break frequency (check the keele paper).
@freddi - thats the design I was referring to. Its obviously a truncated flare, but my understanding is the hypex flare is a good choice for midbass horn, mainly becuase it loads the driver better at lower frequencies for its size compared to a LeCleich or tractrix flare. Why do you think the HD is higher with the 2220? That would look like the more appropriate driver for this horn vs the other. The larger throat probably makes the effective length shorter for that given mouth surface.
@kipman725 - I could make a phase plug for this horn, but it sounds like I'm likely to screw it up more if I do vs just bolting the driver on and see what happens. Having 2 drivers instead of a single one should decrease the flare length a bit, getting me closer to my goals. Is that a legitimate assumption regarding doubling the throat area with another driver, reducing the flare length?
@kipman725 - I could make a phase plug for this horn, but it sounds like I'm likely to screw it up more if I do vs just bolting the driver on and see what happens. Having 2 drivers instead of a single one should decrease the flare length a bit, getting me closer to my goals. Is that a legitimate assumption regarding doubling the throat area with another driver, reducing the flare length?
That's a question I always wondered, but each time from the perspective of the passive filter constraints.
because :
Btw the Altec A5/A7 with a 15" in a WG because of that made ssense to me and always a wanted piece of choice.
To stay more on topic, what about a 80 hz to 600 hz front horn with 10" to 15" driver ? Or here 800 hz for the Yushi bi-radial 800 hz transition ?
there is also something else question, what about the directivity of such mid-bass and the bi-radial Yushi around the cut-off ?
because :
- 80 hz seems more easy as a cut off not to localise the bass origin; although 100 hz can sometimes work as well (room modes, listening room size ?)
- for classical concerts reccordings and live events : most of the acoustical energy stands under circa 800 hz whatever you needs upper ranges for the rest of the instruments, fundamental and harmonics. 80 hz to 800 hz always seemed something logical as a very dynamic full range with air impedance adaptation made by horn with low cone mvt. (certainly a myth too?) . But some expect a full range is better used if working for the human voice so above 150/200 hz male voice, not talking of course about : bass, baryton and tenor singer. Others say, always in the passive crossover context, than 500 hz is the midrange upper limit for cut off to avoid problems in the said ears sensivity windows of 1k to 3K hz !
Btw the Altec A5/A7 with a 15" in a WG because of that made ssense to me and always a wanted piece of choice.
To stay more on topic, what about a 80 hz to 600 hz front horn with 10" to 15" driver ? Or here 800 hz for the Yushi bi-radial 800 hz transition ?
there is also something else question, what about the directivity of such mid-bass and the bi-radial Yushi around the cut-off ?
The Yuichi is more of a 'single' radial than a bi-radial (and there's nothing wrong with that). The compromised height and well rounded vertical profile tends to flip the directivity higher than the 'cut-off'. This means crossing it at the low end would almost always be some kind of compromise.
The 100 hz target was chosen due to size constraints. I dont think that turnover frequency is a problem in stereo configuration with a sub on each side. I'd be concerned with a single sub, but I'm not a fan of mono bass anyways, and it doesn't allow for smooth LF response either having just one sub.
My question is whether I can use a shortened flare with 2 x 12" drivers per horn and whether that will complicate things from a directivity standpoint closer to the upper limit of the horn. Another reason for choosing a midbass horn over a direct radiator setup is the impact of lower mids. I've never been able to fall in love with the average smaller speaker missing that tactile sense of realism in the lower mids. Thats something you only get with a larger speaker, especially a FLH. After all, we hear with our bodies as well as ears and there is a distinct disconnect in listening experience without that physical sense of realism ie. listening with headphones.
I have a choice of the 12MH32 or the 8PE21 and have 4 of each. The 8PE21 isn't going to have enough xmax to keep up with the rest of the system. Its a great mid driver, but not as midbass for a large system playing down that low, at least not at the levels I sometimes play music at. I see no reason why the 12MH32 won't work for this purpose having specs beneficial to horn loading.
The room this system will be in measures roughly 18 ft wide by 29 ft deep with a 20 ft vaulted ceiling. Not a huge room, but not small either and needs more LF and lower mid capability to fill. Listening location is about halfway down the room. LF response is very even with just one significant peak at 50 hz. I can comfortably use 100 w/ch with 90 dB/w floor standing speakers, which will give me about 100 dB at the listening position. That is more than enough in most cases but not for live recordings or some classical, big band jazz, rock with big dynamics. I want to be able to hear a full drum kit at realistic level without compression. Insane you say? Not from my perspective.
My question is whether I can use a shortened flare with 2 x 12" drivers per horn and whether that will complicate things from a directivity standpoint closer to the upper limit of the horn. Another reason for choosing a midbass horn over a direct radiator setup is the impact of lower mids. I've never been able to fall in love with the average smaller speaker missing that tactile sense of realism in the lower mids. Thats something you only get with a larger speaker, especially a FLH. After all, we hear with our bodies as well as ears and there is a distinct disconnect in listening experience without that physical sense of realism ie. listening with headphones.
I have a choice of the 12MH32 or the 8PE21 and have 4 of each. The 8PE21 isn't going to have enough xmax to keep up with the rest of the system. Its a great mid driver, but not as midbass for a large system playing down that low, at least not at the levels I sometimes play music at. I see no reason why the 12MH32 won't work for this purpose having specs beneficial to horn loading.
The room this system will be in measures roughly 18 ft wide by 29 ft deep with a 20 ft vaulted ceiling. Not a huge room, but not small either and needs more LF and lower mid capability to fill. Listening location is about halfway down the room. LF response is very even with just one significant peak at 50 hz. I can comfortably use 100 w/ch with 90 dB/w floor standing speakers, which will give me about 100 dB at the listening position. That is more than enough in most cases but not for live recordings or some classical, big band jazz, rock with big dynamics. I want to be able to hear a full drum kit at realistic level without compression. Insane you say? Not from my perspective.
Last edited:
I've been forewarned regarding the vertical Yuichi pattern flip at 1000. I've heard systems with A290s crossed at 600 which sounded just fine and very even while either sitting or standing, but the HF definitely rolls off faster in the vertical axis. I chose this horn because of its minimal coloration characteristics and better than average horizontal dispersion. I didn't want to cross at 1k as some (or most) larger 2 way systems do with compression drivers. Its been brought to my attention the 600 hz crossover may be overly optimistic, but the driver is more than able to run down well past 600 hz. The horn is the limiting factor. The DCX50 driver is a weird animal but sounds very real and believable. Even on a lesser expo horn, this driver is well behaved and smooth while capable of very high dynamics.