Bass enclosuer for horn system

[nzlowie]

Hi guys

 

I’m thinking about trying a different approach for the bass on my horn system.

At the moment I have a bass horn that doesn’t go really low enough or hi enough to blend nicely with my mid horn. So I’d really need to add a sub-woofer for the lower bass and maybe a mid-bass horn to give the mid bass some more kick. The response is all there and sound very nice on vocals and acoustic music but lacks some real kick when playing rock music.

 

The bass horn does provide nice smooth bass for the range it covers and I may lose some of this with a box enclosure bass setup. Compromises again…

 

My plan is to build a tall - narrow enclosure to house a 12-15” bass and 8” mid bass drivers. The mid horn will go through the middle of the box, bass driver below and mid bass driver above. I’ll use my minidsp to do the crossovers for the bass and mid bass, the latency of the minidsp should help with time alignment of the drivers.

 

For this bass box should I just take someone else’s volume / drivers recommendation and change the box ratio’s (to keep volume) to suit my plan or start from scratch? Don’t really know how to use the box simulation programs……  I’ve build one of Troel Grevensens designs before thought I might just use the bass section from one of these.

http://www.troelsgravesen.dk/Illuminator-4.htm

 

What do you think guys?

[davewantsmoore]

6 minutes ago, nzlowie said:

For this bass box should I just take someone else’s volume / drivers recommendation and change the box ratio’s (to keep volume)

 

Yes, you can do that .... and I guess you'll need to if you don't know how to start from scratch.

 

7 minutes ago, nzlowie said:

What do you think guys?

 

Another, perhaps obvious option would be to get a horn which reaches from your subwoofers to your midhorn....  so like from 100 to 800 or something.

[nzlowie]

Yea, also been thinking about that..... One of Martin's 160hz horns but then still have the 200 odd down. The quater pie horn doesn't go really low so would want to do something there as well.....

That's why I thought just build a box that covers the 30-600 range.
Be a smaller footprint as well.

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[acg]

30 minutes ago, nzlowie said:

That's why I thought just build a box that covers the 30-600 range.
 

 

That is 3-4 octaves of bass...you will get sound but I personally think that region needs at least two to three channels to properly portray, plus you could be met with some rather large attenuation for your horn channels if you use a single 8" driver.  Martin does a 120Hz horn doesn't he?  I would go that with a 4" throat and a decent 8" driver from 100Hz-600Hz and then decide if you want to break up the sub 100Hz into two channels.  If the quarter-pie horn works for you then perhaps just a sub for the lowest octave.

 

I would be thinking horns as low as you can go and then sealed subs below that...

[Paul Spencer]

The first question I'd ask is have you done any in-room testing in the bass and low mid range? This can have a profound impact on what actually makes sense as a plan going forward, unless you change houses more often than speakers! You might find that giant coffin speakers actually have poor bass response. It can happen and it's quite disappointing when you get poor bass from speakers that look like they should really know how to rock. Sometimes this is make or break.

 

The next question is what range do you need to cover? This also relates to the first question.

 

Final question. Are you building separate subs or are you classing your larger woofers as subs?

 

Without knowing your answers yet my initial inclination would be to start with subs that are optimised in number and location to cover the range up to 80 Hz. Mostly one or two are ideal for a single chair with perhaps a spot either side as well. (In some cases the left and right positions are close to ideal, then the situation is different). If using subs, then for the midbass, the choice is easier and you can choose a woofer with extended midrange response. It might mean simplifying the plan where a 12 - 18" woofer covers 80 Hz up to your woofer to horn crossover. If covering say 80 - 500 Hz then you could be looking at a fairly compact sealed enclosure with a 15" driver.

 

With a project like this, there is a network of decisions that work together. What we seek here is a synergy in which the final outcome is better than a series of good parts and apparently sensible choices would deliver. In reality what often can happen with projects like this, is that certain goals are pursued at the expense of things that matter more to the final sound.

 

Let's consider what might happen with different choices. Let's suppose you want to avoid separate subs. We already know this could mean a poor in-room bass response, which might not be fixable with EQ. Moving beyond this what are the other implications? With high sensitivity and greater bass extension being the goal, we move to a ported box with a 15" woofer. The resulting enclosure size is now multiplied and we work on the trade off between size, sensitivity and extension. Even with 40 Hz extension, the box is large for a moderate 94 db sensitivity. The larger box requires more bracing and unlike the sealed box (which we could fill), we're now limited to lining the enclosure. Although the woofer might have potential to meet the horn, care is needed to ensure that enclosure resonances don't limit the useful top end extension of the bass driver. We may at this point be adding in further complexity, with a sealed woofer covering the midrange to meet the horn. In other words, a decision to extend the bass response with a ported design can also limit the upper bandwidth limit. A prototype is a good idea for testing. If you are headed towards a 3 way design as shown in your sketch, then the choice of woofer is likely to be quite different.

 

Yet another consideration is SBIR. When a midrange driver is elevated, you may experience a significant floor bounce dip in its passband. It's something to consider with the type of configuration in your sketch.

[davewantsmoore]

Paul.  My understanding is Dave currently has a horn which covers from 60 to .... not high enough to meet his mid horn (about 600hz).

 

I think it's a good suggestion ....   to use a subwoofer(s) .... and then a driver (or a horn) to cover the range from the subwoofer to his mid horn  (eg.  80 to 600)

[nzlowie]

Thanks guys, great replies.

 

What I'm trying to work around is that I think my quarter pie horn is a bit in no man's land, doesn't go very low or hi so I really need a sub plus mid horn. That's? why I thought of a box with a mid bass driver and good bass driver to cover the lower octaves.

 

My mid horn, 340 Azura with the BMS coaxial driver sounds very good but the bass area needs work. The mid horn doesn't have much kick down low hence me thinking about a mid bass driver or horn.

 

Paul, I'll reply to your post once I'm in front of a real computer, too hard on my phone!

 

Thanks again guys

 

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[davewantsmoore]

1 hour ago, nzlowie said:

What I'm trying to work around is that I think my quarter pie horn is a bit in no man's land, doesn't go very low or hi

 

This is typical of a normal folded (doesn't go high) horn that isn't enormous (doesn't go low).

 

As you know, I have also built a very similar horn.     You could use a different woofer in it to get it to reach higher in frequency ..... but I don't think the dimensions of the horn make it suitable to operate much above bout ~350Hz anyways.

 

 

If you're going to keep your existing 340 horn, and use direct radiators.    I would recommend a "mid bass" driver mounted below your mid horn which covers ~80 to ~600 .... and then true subwoofer(s).

 

You could also cover this range with a horn, but it will be very big ..... think 3/4-ish the mouth size of your "QP horn" .... 3/4 as long, but not folded.

 

[henry218]

If you can build that big, i would suggest top and bottom bass drivers (xo point less than 300hz)

As you will be using minidsp, you can choose drivers with Fs 40-50 with good motor strength and reasonably low cone mass to get that extra dry kick. With sealed its much easier to design the box, as long as it has enough vol for the given driver and sensible bracing.

 

Plus subwoofers of course.

 

 

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[davewantsmoore]

More bass drivers is always good advice  

 

Autocorrect should make subwoofer => subwoofers  

 

[nzlowie]

5 hours ago, Paul Spencer said:

The first question I'd ask is have you done any in-room testing in the bass and low mid range?

Yes due to the size of these horns measurements and eq were done in my listening room. Average of about 5 locations.

 

5 hours ago, Paul Spencer said:

The next question is what range do you need to cover?

Low as possible to around 600hz

 

5 hours ago, Paul Spencer said:

Final question. Are you building separate subs or are you classing your larger woofers as subs?

Wasn't planning on it, the corner horns are big enough and I'm starting to run out of room! As this is only a 2 channel system and not AV i don't really need 20hz

 

5 hours ago, Paul Spencer said:

With a project like this, there is a network of decisions that work together. What we seek here is a synergy in which the final outcome is better than a series of good parts and apparently sensible choices would deliver. In reality what often can happen with projects like this, is that certain goals are pursued at the expense of things that matter more to the final sound.

Yes, understand this and have been finding out about this during my diy horn project!

 

2 hours ago, davewantsmoore said:

If you're going to keep your existing 340 horn, and use direct radiators.    I would recommend a "mid bass" driver mounted below your mid horn which covers ~80 to ~600 .... and then true subwoofer(s)

Was also looking at John Inlow's 135hz mid bass horn.

 

I just thought that a "box" with bass and mid bass drivers would satisfy the range from 30 odd hz to the 600hz range which would then hand off nicely to my mid horn.  

 

As mentioned earlier the response doesn't really have any real holes in the range from 40 to 6khz but I just feel the mid bass needs some kick.....

Edited May 25, 2017 by nzlowie

[davewantsmoore]

1 minute ago, nzlowie said:

Was also looking at John Inlow's 135hz mid bass horn.

 

 

Yes, just the sort of thing I was thinking of.     I think he has one which might go a little lower too, if you have space.

 

Get rid of the QPs

Build Inlow ~100Hz horn, or similar

Build subwoofers to cover below the new midbass horn

... build more subwoofers.

 

: party :

 

 

[nzlowie]

3 minutes ago, davewantsmoore said:

Get rid of the QPs

My thoughts as well.....

 

4 minutes ago, davewantsmoore said:

Build Inlow ~100Hz horn, or similar

 

Do you think Martins 160hz would go low enough to hand over to a sub or 2? I thought of getting the 160hz horn and swap the 340 horn for the 425 or 550 which might give better loading for the tweeter of the coaxial.

Would also help build a nicer looking system....But then someone made a comment that horn systems aren't any good in smaller rooms, I'll be moving in a year or so and yes my listening room will be smaller.....

 

So part of me is also saying go back to a simple box more suitable for smaller rooms.

http://www.troelsgravesen.dk/AT-3WC.htm

[henry218]

As speakers get bigger and taller, you will need to sit further to get better holistic image of the speakers.


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[nzlowie]

Had a thought about 4 o'clock this morning..... Why don't I just try sitting the horn on top of my DTWQT'S and see how they sound. Just use the minidsp and amp that's now running the bass horn!

 

At least this might give me an idea if it's worth progressing.

 

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[davewantsmoore]

20 hours ago, nzlowie said:

Do you think Martins 160hz would go low enough to hand over to a sub or 2?

 

Sure ... but this will mean the crossover to the subwoofer will be quite high in Hz .... and so the subwoofer placement becomes restricted to being close to the main speakers.

 

20 hours ago, nzlowie said:

But then someone made a comment that horn systems aren't any good in smaller rooms

 

It's quite a generalisation ....  this would depend on the coverage pattern of the horn system.     Horns can achieve some of the most well controlled coverage patterns (one of the major reasons to use them) .... but many horn systems have really problematic coverage patterns.

 

 

 

[Guest atilsley]

I've enjoyed the 340 Azura....

 

Consider OB config....I'm building an OB using dual 18 inch AE Dipole woofers. This will partner with a 300Hz Iwata horn....with xover point around 550/600Hz.

 

The dipole woofers will give the best of both worlds...deep bass, plus fast/clean.

 

You could play around with the design to sit vertically or horizontally...allowing good adjustment for horn placement.

 

Anyway, just a thought....all the best with your project...sounds good.

 

Andrew 

[nzlowie]

Cheers Andrew, could also be an option. I noticed on Troels site he said a wide baffle was the way to go for low bass on an open baffle.
Let me know how yours ends up.....
With your experience I'm sure it's going to sound great!

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[Sebastian Schlager]

Hi nzlowie, nice project you have going on. I have an idea for a solution for 80-600 hz, with around 105 dB/w. It's a design a friend of mine came up with and is basically a 1/4 wave back loaded horn + waveguide to support higher frequencies. This box has only been simmed in Hornresponse and not build yet, but I am about to before long. It uses 2 x 10" Eminence Delta-10A drivers, which has the right T/S for this thing (we call it Super Planar Kick Bin) Lower driver should be low passed at 100 hz 1. order. 

[nzlowie]

Hi nzlowie, nice project you have going on. I have an idea for a solution for 80-600 hz, with around 105 dB/w. It's a design a friend of mine came up with and is basically a 1/4 wave back loaded horn + waveguide to support higher frequencies. This box has only been simmed in Hornresponse and not build yet, but I am about to before long. It uses 2 x 10" Eminence Delta-10A drivers, which has the right T/S for this thing (we call it Super Planar Kick Bin[emoji4]) Lower driver should be low passed at 100 hz 1. order. 

Thanks, would love to find out more about this project. So the drivers operate in full parallel or do they cover different frequencies?

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[Sebastian Schlager]

Yes, they operate in parallel, but only under 100 hz. You put a coil on the woofer below for a 1. order filter, so it "helps" in the bass and only contributes little above 200 hz (-6db). The top woofer runs fullrange, with a highpass at 60-65 hz for protection.