I built already a few MEH's - single and dual expansion of pretty large dimensions. On the other hand, I built some really nice large horns (like the WN300ALO) and I was thinking about a way of using these together somehow.
And I think it should be actually possible to build a MEH without the HF driver and use the large horn on top of it. What would be the motivation?
1) To make the horn less deep - the woofers would be mounted from the sides, not at the back of the horn - which should save some considerable depth. Maybe the acoustical center could be quite well matched in distance from the listener.
2) More SPL/efficiency in a more compact box - e.g. 4 woofers could be enclosed in a relatively simple back box, the result being more "squarish" than when mounted from the back in a separate chamber - the volume behind the horn would be used as the "free" back chamber.
3) Bandpass filtering could reduce distortion and make the low pass easier, simply by using peak filters at the high end (with a DSP).
There are definitely some cons to this. I can imagine a passive crossover would be difficult, but not impossible.
One of the inspirations was my large test MEH, where a single 8PE21 did a really nice midbass job - which it could also do in a dedicated traditional midbass horn, which would be definitely much deeper. I can imagine 4 x 8-12" or 2x15" could be still relatively compact (compared to the size of the HF horn).
I will try to run some Hornresp simulations using the OD model with the woofers I have at hand. With a bit of effort, a different than conical profile could be used to improve the low end loading. The target for the low end is somewhere around 90 - 120 Hz, where the large bass horns would take over.
Any thoughts about this being a good idea or a bad idea are very welcome!
And I think it should be actually possible to build a MEH without the HF driver and use the large horn on top of it. What would be the motivation?
1) To make the horn less deep - the woofers would be mounted from the sides, not at the back of the horn - which should save some considerable depth. Maybe the acoustical center could be quite well matched in distance from the listener.
2) More SPL/efficiency in a more compact box - e.g. 4 woofers could be enclosed in a relatively simple back box, the result being more "squarish" than when mounted from the back in a separate chamber - the volume behind the horn would be used as the "free" back chamber.
3) Bandpass filtering could reduce distortion and make the low pass easier, simply by using peak filters at the high end (with a DSP).
There are definitely some cons to this. I can imagine a passive crossover would be difficult, but not impossible.
One of the inspirations was my large test MEH, where a single 8PE21 did a really nice midbass job - which it could also do in a dedicated traditional midbass horn, which would be definitely much deeper. I can imagine 4 x 8-12" or 2x15" could be still relatively compact (compared to the size of the HF horn).
I will try to run some Hornresp simulations using the OD model with the woofers I have at hand. With a bit of effort, a different than conical profile could be used to improve the low end loading. The target for the low end is somewhere around 90 - 120 Hz, where the large bass horns would take over.
Any thoughts about this being a good idea or a bad idea are very welcome!
Of course you can! It's what I cobbled together when TD gave me some hints in a PM back before he went public. Note some of the W.E. side throat loaded cinema bass horns. Drat! More pics gone! 
This is one man's version.
This is one man's version.
Great. I am getting some really interesting figures while playing with Hornresp. I will try to come up with a meaningful combination of available drivers and available space. Dual 8PE22 offset horn looks interesting so far.
This is just a first trial, roughly 60 x 60 x 60 cm with two 8PE21s, Hornresp record attached:
Theoretical max SPL in half space:
It is just a quick sim, but it should fit my goal. I forgot to mention that my targeted horizontal dispersion is around 60 degrees.
Theoretical max SPL in half space:
It is just a quick sim, but it should fit my goal. I forgot to mention that my targeted horizontal dispersion is around 60 degrees.
The model in OpenSCAD is getting closer to its final shape:
Raw Hornresp model:
And with a bit of EQ:
I need to have a look if I still have some 16 mm chipboard left🙂
Raw Hornresp model:
And with a bit of EQ:
I need to have a look if I still have some 16 mm chipboard left🙂
GM - what do you figure the spacing was of Cerwin's Dhorm tweeters? - Is there a modern equivalent of those units? (I had a pair of S1 Loud - gas bag/6th order reflex 3 way with large waveguide on the Dhorm back in the 80's and they would play crazy loud in a small room with a DH200. I'd love to have a similar diy effort but am worse than broke - plus too "old" and worn out - lol
I am away from home this week and I also need to finish the "Runt" clones first. I want to measure them also without the CD as an offset midbass hor although with just 2x8".
I will maybe revive this project - using my 90x60 MEH as bass unit surprised me with its performance.
Since it will be placed on the floor, would it make sense to make the horn vertically asymmetrical? Flat bottom and the upper wall at an angle instead of angled top and bottom - it would save some wood - would there be any benefits or drawbacks to this?
Since it will be placed on the floor, would it make sense to make the horn vertically asymmetrical? Flat bottom and the upper wall at an angle instead of angled top and bottom - it would save some wood - would there be any benefits or drawbacks to this?
It's what we did in some prosound apps and I did in a few high end HTs and IIRC seems like I saw a picture of one at one of the USA DIY Meets ages ago now, so if it suits your app......... Ages ago now someone sawed a 511 horn down the middle where it was welded together, made an adapter to mount a cheap, small tweeter horn driver to it and dang if didn't load that little driver down to nearly 500 Hz (at low power of course!), so proved a valuable POC that in a way also works with what I'm currently using; i.e. the Altecs I've posted pics are MIA service wise, needing new HF diaphragms, XO caps installed, so have RS Minimus 7 mounted flush on their sides, making the empty horns acoustic amplifiers down to their ~250 Hz cutoff and increases system efficiency to the point where folks not familiar with the Altec's sound assume its them they're enjoying at (their) high average SPL till they get very close to the 7s to clearly hear the acoustic BSC 'step up' disconnect, so to speak.
You'll have 3 benefits of putting the bass/mid unit on the floor and having a flat bottom. No floor cancellation, all the space below the tweeter horn can be used to create a big enough upper wall to do the job needed, and the source would be further from the ceiling widening the allowable ceiling angle for controlling the ceiling reflection.
If you can implement the proper control with a symmetrical waveguide, then you might prefer to do that however the chances are that you'll run into compromise there as well. It's a matter of which is more workable.
If you can implement the proper control with a symmetrical waveguide, then you might prefer to do that however the chances are that you'll run into compromise there as well. It's a matter of which is more workable.
Thanks for the feedback! The construction of such a horn should be really easy using available right angle triangular bars and some CNC.
This is how I imagine it now - just the panels creating the horn.
Would it be too crazy to add mids to the horn if the 12" could not play high enough?
Would it be too crazy to add mids to the horn if the 12" could not play high enough?
It appears you were going for up to around 400Hz from the 12", which is already high enough in frequency to draw the sound image (sound stage) to the floor location. Going higher will make it even more obvious that the apparent source is on the floor.
Personally, I prefer anything above ~100 Hz from near the same location to prevent the sound stage drifting up and down with frequency.
And I don't want the soprano singer standing on the head of the baritone 😉
A good point to consider. The truth is that now I use the bass part of the horn up to around 260 Hz and I did not observe any bad effects, maybe I do not know what to listen for.
My point in #16 would only apply if the speakers providing the upper frequencies were located around ear level.
If both are located near the floor, the apparent source wouldn't drift with frequency, it would be consistently below.
That said, vertical location sensitivity reduces with frequency, you may just not notice the difference.
If both are located near the floor, the apparent source wouldn't drift with frequency, it would be consistently below.
That said, vertical location sensitivity reduces with frequency, you may just not notice the difference.