60 Degree DIY Mid Hi - AKA PM60

Re: 60 Degree DIY Mid Hi

Mark Wilkinson said:
Yes, I understood you were talking about freq of control, sorry if i didn't convey that in my last post....

In the rule of thumb formula, 10^6 / (degrees x inches )..... what is inches? cone diameter? horn width/ height? box width / height? array width / height? (assuming they array well)
Just trying to get a sense of how to intuitively apply the rule...

BTW, thx for the encouragement a few months back to attend smaart class. Just finished a 3 day that was well worth it. Learned alot, and learned a whole lot more questions !!! :o~:-o~:eek:
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The "inches" is the outside sides of the horn (NOT counting the mounting flange).

However (as most things in audio) it is not as simple as measuring it. If the horn has a "flare break" (like on constant directivity horns), then the actual-effective size of the horn is somewhere between the edge of the flare break and the outside of the final flare.

Some horns have flare breaks, others don't Some are nice and sharp, and others are rounded.

The purpose of the flare break is to "ease" the transition of the horn. You generally don't want the horn to "stop" quickly, or else some "odd" things start to happen (reflections back into the horn-oddities in the actual pattern and so forth.)
 
Re: 60 Degree DIY Mid Hi

Mark Wilkinson said:
Thanks for those two explaining posts. They are slowly beginning to make some sense....especially as I read back over previous posts where you describe modeling and design decisions...

In thinking about building some more 60 DIY boxes.... I'd love to get the XT1464 all the way inside the walls. Does that necessary extra width matter as far the way the slot under the 12" expands into the beginning of the MF horn?
I'm thinking not much really,..... partly because I see it's ok to lop the corners off the box, the way you're doing.
I mean, doesn't the corner "lop off" make for a slight restriction?....which evidently doesn't matter...? So maybe things about the MF horn aren't so critical....
Maybe the right question is what dimensions or flare particulars are critical?

And I know you left your 60 degrees the full depth you had available without cutting any off. That would appear to give some help to directivity per your above post.
Did you keep the depth for that? , or to keep your box looking as good as it does !
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Probably the most critical part of the horn in this case is its length.

The bottom two SIM’s show what happens if we change the throat area of the horn from 300 sq-cm to 400 sq-cm and what happens if we increase its length by 100mm or 4 inches (top)

To get the DIY to work in this case I have pushed things to the practical limit. The horn is as small and short as you can get away. To extend the bass response from about 150Hz to 100Hz I added some ports.

The cost is some ripples in the frequency response; because the horn/speakers are all behaving in a linear manner you can fix it with some DSP correction and everything will behave perfectly. It’s only when you try to correct those things that are non-linear that sounds wrong or processed if try too hard.

This is the bit that many people don’t understand. You can describe mathematically a speaker’s behaviour in an electrical type of model. This is what Thiele and Small did. Similarly you can describe the electrical correction the DSP does in the same way. The net result is the sum of both. The proviso is the speaker / horn is behaving in a linear manner – i.e. in its piston range where is response is fundamentally determined by the cone area, the strength of the motor, the weight of the cone, and the spring and dampening force of the suspension.

In the case of the DIY all the drivers are in their piston range. There are a few minor issues within the compression driver where the HF and VHF have to combine, but these are much less than having separated drivers trying to cover the required frequency range. It also results in much less size and weight.

You asked about putting the HF horn within the walls of the box. One possible issue is the edge of the box causing HF reflections or diffraction issues. At some point the discontinuity between width of the throat entrance and the width of the start of the horn may be an issue … not exactly sure where this will become significant. The obvious other issue is size and weight.
 

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Re: 60 Degree DIY Mid Hi

Peter Morris said:
The cost is some ripples in the frequency response; because the horn/speakers are all behaving in a linear manner you can fix it with some DSP correction and everything will behave perfectly. It’s only when you try to correct those things that are non-linear that sounds wrong or processed if try too hard.
This is the bit that many people don’t understand. You can describe mathematically a speaker’s behaviour in an electrical type of model. This is what Thiele and Small did. Similarly you can describe the electrical correction the DSP does in the same way. The net result is the sum of both. The proviso is the speaker / horn is behaving in a linear manner – i.e. in its piston range where is response is fundamentally determined by the cone area, the strength of the motor, the weight of the cone, and the spring and dampening force of the suspension.
Click to expand...

This right here is one of the keys to modern loudspeaker design - knowing what can and cannot be fixed with DSP, and designing accordingly.
 
Re: 60 Degree DIY Mid Hi

Here is a quick report on my first gig with two 60 deg boxes.
We set up in a parking lot for a concert/movie premier. There were about 500-600 people spread out pretty wide. The 60 deg were not ideal for this coverage so we added some front fills on the downstage lip.
We powered the DIYs with 2 iTech4000s per box, DSP via the Driverack.
They easily kept up with 8 single 18 SRX subs. One thing that stands out is distance that they stay clear and defined. We were visited by the police with a sound complaint from 3 blocks away, which was amazing considering we were not driving them very hard or loud.
During the movie, the DIYs combined with the subs sounded like the best home theater I've ever heard. Very precise reproduction of voices, very real sounding.
I can't wait until the 90 deg horns come in. This box meets or exceeds my expectations.
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Don J Davis said:
Here is a quick report on my first gig with two 60 deg boxes.
We set up in a parking lot for a concert/movie premier. There were about 500-600 people spread out pretty wide. The 60 deg were not ideal for this coverage so we added some front fills on the downstage lip.
We powered the DIYs with 2 iTech4000s per box, DSP via the Driverack.
They easily kept up with 8 single 18 SRX subs. One thing that stands out is distance that they stay clear and defined. We were visited by the police with a sound complaint from 3 blocks away, which was amazing considering we were not driving them very hard or loud.
During the movie, the DIYs combined with the subs sounded like the best home theater I've ever heard. Very precise reproduction of voices, very real sounding.
I can't wait until the 90 deg horns come in. This box meets or exceeds my expectations.
Click to expand...



That’s fantastic, I am glad they’re working so well and that you able to replicate some of the great results I have been getting. For its size and weight I’m not aware of any commercial product that goes as loud or sounds as good … at any price :)~:-)~:smile:

FWIW the 90 degree version sounds very similar, but in practice it’s MUCH wider than the 60 degree horn which rolls off rapidly outside of its nominal pattern.

Now we just have to give them a better name than DIY Mid-Hi … any suggestions :?:
 

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Re: 60 Degree DIY Mid Hi - They need a name ?

Peter Morris said:
That’s fantastic, I am glad they’re working so well and that you able to replicate some of the great results I have been getting. For its size and weight I’m not aware of any commercial product that goes as loud or sounds as good … at any price :)~:-)~:smile:

FWIW the 90 degree version sounds very similar, but in practice it’s MUCH wider than the 60 degree horn which rolls off rapidly outside of its nominal pattern.

Now we just have to give them a better name than DIY Mid-Hi … any suggestions :?:
Click to expand...

I suggest the Morris Major for the 90 degree and the Morris Minor for the 60 degree:)
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Ivan, thanks for the good pieces of continuing education.

Peter, thanks for the further info on the design trade offs. I'm seeing why your boxes have ended up where they are.
I am definitely in the process of building another round of 60 deg DIYs, and at this point am inclined to copy yours, corner lopping included, if I decide I can't go with mostly 12mm for weight reduction.
Also been thinking about this idea for trying to measure box resonances, to be able to just try things and see how fill or bracing might work with a lighter cab........http://www.mh-audio.nl/tips\ach-01.htm

Have to build new 60 degrees because I shredded one of the 12" RCFs,...... and it looks like the cone hit one of the BMS HF terminals.
I knew I was playing it close, but still am a little surprised it hit. Maybe I forgot to high pass, dunno.....been trying so many things I get confused :)
At any rate, this pushes me over the edge for building another round, if only to gain some more XT1464 clearance.
I'll use the existing boxes as 90 degrees only.

Don, great to hear your gig went well. I bet the DIYs are perfect for an outdoor HT setup with their clarity, other than the wider dispersion you needed.
As Peter said, the difference in pattern between the 60 degree and the 90 degree is waaay more than the numbers would indicate. I guess because how abruptly the 60 degree rolls off outside its pattern.

I too am amazed by their throw for their size.
Probably the real reason I shredded a cone is that I just had to push one for grins a few times this weekend.
I put one 60 deg on top of 3 labhorns, which was almost a good match but the labhorns were on a deck and not fully half space loaded. Needed one more lab i think...but three would probably be good if they were fully on the ground.
Didn't meter anything but I'm guessing it had to be at least 105 db C slow at a measured 150 feet....which implies 138 at one meter.
And sooo very clean !! Till it broke haha.....glad I only run one at a time !

edit... I should add that the boxes I built have alot less clearance between the coax and the 12" drivers because of the way I did the 12" baffles and spacers; not because the posted plans lack clearance.
I used a 12mm spacer on top of a non-routed 18mm baffle board.
I don't want others to have any clearance concerns here.....
 
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Re: 60 Degree DIY Mid Hi - They need a name ?

Hi Mark ...very sad news :(~:-(~:sad: Do you have any pictures of the cone failure etc.

You need a HP at about 100hz - 24 dB oct, if you don't things will get ugly very quickly if you drive them hard.

Other than that minor hiccup how are they going?

3 Lab subs is quite a lot ... here is 6 of mine a side some time a go https://www.youtube.com/watch?v=A-XPTioNoZA
 
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Re: 60 Degree DIY Mid Hi - They need a name ?

Peter Morris said:
Hi Mark ...very sad news :(~:-(~:sad: Do you have any pictures of the cone failure etc.

You need a HP at about 100hz - 24 dB oct, if you don't things will get ugly very quickly if you drive them hard.

Other than that minor hiccup how are they going?

3 Lab subs is quite a lot ... here is 6 of mine a side some time a go https://www.youtube.com/watch?v=A-XPTioNoZA
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Hi Peter, yep, just a minor hiccup....besides, as an old 2 stroke engine builder I know damn well you have to break things to find the edge :)
And really, the edge here wasn't about over driving the DIY; I either inadvertently left out high pass, or simply cut the design clearance too much. Either way, it seems to look like the cone hit a terminal.
shred.jpg
My guess is the high pass, because I have been going back and forth controlling x-over for the MiD section with either an X-32 matrix out, or with the PLD processing amp.
I've been using 24 db no lower than 90hz.

Yes, other than this hiccup, they are going very well, thx. I enjoy them inside as home gear, almost as much as cranking outside.
Their clarity reminds me of cleaning my windshield, if that analogy makes any sense....

Do you still have 12 labsubs? Video looked waay cool !!
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Mark Wilkinson said:
Hi Peter, yep, just a minor hiccup....besides, as an old 2 stroke engine builder I know damn well you have to break things to find the edge :)
And really, the edge here wasn't about over driving the DIY; I either inadvertently left out high pass, or simply cut the design clearance too much. Either way, it seems to look like the cone hit a terminal.
View attachment 12820
My guess is the high pass, because I have been going back and forth controlling x-over for the MiD section with either an X-32 matrix out, or with the PLD processing amp.
I've been using 24 db no lower than 90hz.

Yes, other than this hiccup, they are going very well, thx. I enjoy them inside as home gear, almost as much as cranking outside.
Their clarity reminds me of cleaning my windshield, if that analogy makes any sense....

Do you still have 12 labsubs? Video looked waay cool !!
Click to expand...

Yes I still have 12 Lab subs ... I did some big gigs with them when I first built them.

Here is a plot of the Xmax - Its 8.6 mm at 1300 watts / 100Hz. Hence the 10mm spacer. Typically with a 100Hz 24dB LR crossover and some appropriate limiters I would expect more like the grey line i.e. 6 dB down at 100Hz which is about 4.5mm. The rated Xmax is 5.5mm. The compression ratio is 2.8 :1, so I would not expect that to cause any problems with the cone.

I think you are correct, that you may have forgotten the HP filter and the compression driver terminal hit the cone.

...and yes cleaning your windshield absolutely makes sense. I suspect from now on, most PA speakers will sound like they have dirty windshields to you, and polishing the front grill won't help :-)
 

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Re: 60 Degree DIY Mid Hi

Klaus Zimmermann said:
peter, not that i wanna push you, in which timeframe can we expect to read/see some :D~:-D~:grin:
TX for all you do for this forum :thumbup::thumbup::thumbup:
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The double 21 is nothing fancy. It’s basically just two B&C designs joined together.

The trick is to keep the weight down. The B&C 152’s weight 40 lbs each!

To do that I am going to use 19mm ply and corner ports because they brace the walls without adding weight, plus some additional bracing on the back panel & walls.

For me, weight is more important than port turbulence, so the port design is not fancy. The box also has to be the appropriate size so it can be combined with our existing double subs and can it be used as a base for ourTurbosound Flex Array as well as the DIY.

I considered building a design like this http://www.dasaudio.com/en/p/ux-221-2/. It gives you a bit more efficiency, but the box weighs 130 Kgs.

I have the drivers in stock and hopefully I can start building soon :-)
 

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Re: 60 Degree DIY Mid Hi - They need a name ?

Peter Morris said:
Yes I still have 12 Lab subs ... I did some big gigs with them when I first built them.

Here is a plot of the Xmax - Its 8.6 mm at 1300 watts / 100Hz. Hence the 10mm spacer. Typically with a 100Hz 24dB LR crossover and some appropriate limiters I would expect more like the grey line i.e. 6 dB down at 100Hz which is about 4.5mm. The rated Xmax is 5.5mm. The compression ratio is 2.8 :1, so I would not expect that to cause any problems with the cone.

I think you are correct, that you may have forgotten the HP filter and the compression driver terminal hit the cone.

...and yes cleaning your windshield absolutely makes sense. I suspect from now on, most PA speakers will sound like they have dirty windshields to you, and polishing the front grill won't help :-)
Click to expand...

The more I think back, the more certain I am that high pass was missing. Because I never heard any sign of stress from the DIY when pushing it.
But all of a sudden, I heard a breakup that I first thought was coming from the BMS coax....and it wasn't at pushing levels...
I'm now leary of using the X-32 matrix outs as x-over...they work well enough...but it's just too damn easy to turn off the EQ which drops the x-over too ....especially out in the sun running the x-32 from a tablet....

Oh, do you still use the labsubs? Where did you find you like to low pass them? I like to keep them no higher than 80hz...but that may just be because I haven't yet learned how to phase align them with the tops....
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Mark Wilkinson said:
The more I think back, the more certain I am that high pass was missing. Because I never heard any sign of stress from the DIY when pushing it.
But all of a sudden, I heard a breakup that I first thought was coming from the BMS coax....and it wasn't at pushing levels...
I'm now leary of using the X-32 matrix outs as x-over...they work well enough...but it's just too damn easy to turn off the EQ which drops the x-over too ....especially out in the sun running the x-32 from a tablet....

Oh, do you still use the labsubs? Where did you find you like to low pass them? I like to keep them no higher than 80hz...but that may just be because I haven't yet learned how to phase align them with the tops....
Click to expand...

Something I should add - because the horn is ported, once you go below the port tuning frequency the Xmax will increase dramatically. If the enclosure was sealed like a normal horn, the volume of the air / pressure inside the box caused by the cone movement will limit the cone's travel.
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Peter Morris said:
Something I should add - because the horn is ported, once you go below the port tuning frequency the Xmax will increase dramatically. If the enclosure was sealed like a normal horn, the volume of the air / pressure inside the box caused by the cone movement will limit the cone's travel.
Click to expand...

Yes, thx, this I'm familiar with. I guess knowing my proclivity to push things, I should probably hold x-over to no lower than 100hz...
 
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