60 Degree DIY Mid Hi - AKA PM60

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

Peter Morris said:
BTW, Don & Mark ... how are your boxes going. I have made one small change to my settings for the 60 degree box raising the crossover point from 600Hz to 630Hz.
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Hi Peter, I had the 90 degree set up outdoors this weekend. Lot's of neighbors and friends enjoying a homemade block party.
The DIY simply sounded wonderful.
I had the JTR 3TX in a side by side because a friend is considering them for purchase. Everybody was very impressed by the huge output and great sound from the 3TX, but you could see the wow on their faces when I switched to the DIY....it was this way for 100% of those who heard level matched A/B comparisons.
A while back you said there would probably be about a 10 db capability difference between the two....I think that's about right...
So in a nutshell, I remain a very happy camper ! And will be building 2 more 60 deg boxes, using the B&C 12".
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Don J Davis said:
How well do you guys think boxes with the RCFs and B&Cs would play together side by side? Is it even a good idea?
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I'm hoping to just put two rcf boxes together on one side, and same for the b&c's on the other side......figuring that the splayed pairs need to match as closely as possible, but the difference between L/R sides probably doesn't matter too much...
Peter?
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Mark Wilkinson said:
I'm hoping to just put two rcf boxes together on one side, and same for the b&c's on the other side......figuring that the splayed pairs need to match as closely as possible, but the difference between L/R sides probably doesn't matter too much...
Peter?
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The reason I used the B&C in the 60 degree version was that I already had 4 drivers ... and they work very well. The problem with mixing the two is that the B&C needs a different EQ. They have a slightly different cone weight and BL product and as such the lumps and dumps in the frequency response occur at slightly different frequencies and levels ... it may be OK ????

Here is the power response Sim -- The RCF is the dark plot.
 

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

Hey Peter,

Have you measured them in the real world? I am pretty skeptical of these kinds of fine-grained comparisons in simulation. Assuming the simulator is accurate (big assumption, especially for horns - sealed and ported boxes are much easier to simulate but even then you can usually only get close) you are then also assuming that RCF and B&C measure their loudspeakers in a similar way and publish similar results. There are lots of incredible loudspeakers out there on paper, but a lot fewer once you actually put power to them.

Since you have these on hand I would just measure in the physical and see whether the results are acceptable.
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Bennett Prescott said:
Hey Peter,

Have you measured them in the real world? I am pretty skeptical of these kinds of fine-grained comparisons in simulation. Assuming the simulator is accurate (big assumption, especially for horns - sealed and ported boxes are much easier to simulate but even then you can usually only get close) you are then also assuming that RCF and B&C measure their loudspeakers in a similar way and publish similar results. There are lots of incredible loudspeakers out there on paper, but a lot fewer once you actually put power to them.

Since you have these on hand I would just measure in the physical and see whether the results are acceptable.
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Hi Bennett,

I have measured them both and they line up quite well with SIM, but that SIM is the power response and is not corrected for directivity, so the SPL response is different.

Horn Response will not do an SPL SIM with a ported horn so you have to take you best guess. You can however model the horn without the port which I have done. It is of course missing the LF boost you get from the port.

Below are two of the B&C drivers at 1 watt and 1600 watts (800 each). You can see what happens when you start to include directivity … 110 dB 1w @1m.

The reason for the difference between the RCF & B&C has nothing to do with quality of the speakers. The response with respect to the driver choice is fundamentally determined by the cone mass and the motor strength and it’s just a matter of finding the best balance to suit this horn.

Because I have pushed the design limits and the horn is a little small, the response is not flat. Hence the box was always intended to be used with DSP. When you do this the results are stunning.

The measured response with the B&C driver is also shown below.My best guess for the LF horn is nominally 105 dB w/m ... peaking at about 110 dB between 400Hz and 600Hz

When I have some spare time I will try and measure the RCF and B&C in the same enclosure and post the results as you suggested.
 

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

Hey Peter,

I didn't mean to imply that I though the RCF transducers were of poor quality - not at all. Simply that in my experience comparing transducers based on their paper specifications between manufacturers is not reliable. We are internally consistent, and I'm sure RCF is as well, but I would be surprised if the method they use to determine Mms (for instance) is the same as ours. In the end a quality manufacturer like RCF is likely to be closer to our reporting methods than some others, they have sophisticated customers who expect to be able to achieve real world results from their paper specifications and their designs likely hold up consistently under pressure as well.
 
Re: 60 Degree DIY Mid Hi - They need a name ?

I am confused by the statement that HR wont sim a ported horn?

I have simulated quite a few designs that are FLH with ported rear chambers. is this not the same thing as your talking about Peter?
 
Re: 60 Degree DIY Mid Hi - They need a name ?

David Chrapla said:
I am confused by the statement that HR wont sim a ported horn?

I have simulated quite a few designs that are FLH with ported rear chambers. is this not the same thing as your talking about Peter?
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Not quite the same thing - HR will SIM a FLH with a port and produce a power response but that does not include directivity. Directivity is need to predict the SPL, and that can add quite a bit more level.
 

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

Can someone point me to the finalized plans and sketch up files, I wanna shoot this to my builder to see how much it would cost me to put together..

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

Jason Joseph said:
Can someone point me to the finalized plans and sketch up files, I wanna shoot this to my builder to see how much it would cost me to put together..

Many thanks..
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Hi Jason,
Since this is a DIY project there are few different versions being made. Peter's, Mark's and mine are slightly different. Mine is a little wider and deeper and I chose to go with a wrap around grill. Also, mine has angled corners that are built piece by piece where Peter wisely just made the box square and cut off the corners with a saw.
All that to say I'm glad to give what ever drawings I have but I'm not sure which version you want.

Peter, Mark, should we come up with a "final" universal version that can be posted? I'd be happy to make the changes to the drawings. Your thoughts?
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Don J Davis said:
Hi Jason,
Since this is a DIY project there are few different versions being made. Peter's, Mark's and mine are slightly different. Mine is a little wider and deeper and I chose to go with a wrap around grill. Also, mine has angled corners that are built piece by piece where Peter wisely just made the box square and cut off the corners with a saw.
All that to say I'm glad to give what ever drawings I have but I'm not sure which version you want.

Peter, Mark, should we come up with a "final" universal version that can be posted? I'd be happy to make the changes to the drawings. Your thoughts?
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Hi Don, I think this is a great idea....and thanks for your continuing drafting support.

It can't but help folks, and I know we have both said we want to build a couple or more boxes too...

Tomorrow, I'll float what my personal design choices have been, along with a few questions for you and Peter re your boxes and optimization .....
.....just to help move towards a 'universal' plan.
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Mark Wilkinson said:
Looks great Peter ! Is it made out of steel or aluminum ?
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Its a bit cheap and cheerful - I just welded it up out of some pieces of steel I had lying around. From memory its a bit of 65mm x 32mm x 2.5mm RHS (that's bigger than it needs to be) and some 40mm x 5mm flat bar ... I also had a bit of pipe that was the correct ID.

The box inserts are made from some 10mm couplers (nuts about 25mm thick) and some 40mm x 3mm flat bar.
 
Re: 60 Degree DIY Mid Hi - They need a name ?

Mark Wilkinson said:
Hi Don, I think this is a great idea....and thanks for your continuing drafting support.

It can't but help folks, and I know we have both said we want to build a couple or more boxes too...

Tomorrow, I'll float what my personal design choices have been, along with a few questions for you and Peter re your boxes and optimization .....
.....just to help move towards a 'universal' plan.
Click to expand...

That's a great idea :)~:-)~:smile: Thanks!


FWIW here is an interesting line array using similar components http://www.codaaudio.com/index.php?id=2524

http://www.bmsspeakers.com/index.php?id=bms_4507nd
 
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Re: 60 Degree DIY Mid Hi - They need a name ?

Peter Morris said:
That's a great idea :)~:-)~:smile: Thanks!


You bet, and thx to you guys !

Ok, just to try to help move towards some "universal" 60 degree plans....


In my mind, the majority of thinking comes down to choices for width, depth, 12" baffles, HF horn baffle, and back corners. And of course plywood thickness. Height seems to be the one thing that pretty much stays fixed....:?~:-?~:???:

* Ply Thickness........ my vote would be for plans drawn up for 15mm....seems like a good middle of road, and it is available in baltic birch

* Width....seems like choices are either ..
1. hold the exterior at, or slightly wider, than the XT1464 ...so 380mm + 0-6mm, or
2. hold interior width to fit the 380mm horn + a couple mm for wiggle room. Net decision: say 386mm vs 412mm (w 15mm ply)

I'm leaning towards the wider version for ease of construction and opportunity for one piece HF horn baffle.
I figure the wider version adds about 2 lbs....

* Depth....my vote here is the way Peter did his ...455 deep, with front set back of 30mm for HF horn baffle. But this vote is assuming this extra depth (455mm) vs the 90 degree version (430mm) helps the MF horn response? If not, why have it?

But if we do go with 455mm, i'm under the impression the cabinet shouldn't extend past the HF horn mouth due to diffraction,… and that's why Peter has it stepped...correct?
And if we go this way, we need new MF horn piece dimensions...yes?
I figure the extra depth adds maybe another pound and a piece..


* 12" baffles. Right now, I'm thinking 15mm ply routed out 6mm, with a 6mm spacer ring, for a 12mm xmax clearance. This is the lightest strongest alternative I have been able to picture.
Question for you guys....what do you think strengthwise, of your baffles after routing? What's the minimum thickness you would leave at the deepest route?

* HF horn baffle..... I've already voted for the extra width to get it inside and make it one piece.
I also like the idea of a non-beveled baffle, on the top and bottom edges, where it joins the MF horn flares. It was very easy to make a baffle with square edges that mated to the bevel on the MF horn flares that was simply rotated 90 degrees, to make the bevel be perpendicular to the front of the speaker.

* Corners....make the box square for simplicity and let any brave souls lop off corners like Peter did !


Not so ‘universal’ thoughts….. Also, REALLy thinking to make at least the back, top, and bottom out of 12mm BB... (if not the sides too.. It wouldn't be too hard to put a couple of side to side braces in .)
That could get her down below 70lbs.

But I would suggest keeping the 'universal’ plans at some constant ply thickness and let us tinker at our own peril :o~:-o~:eek:
Hope these beginning suggestions help get a dialog going ....
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Re: 60 Degree DIY Mid Hi

My 2c worth ...

1) Ply wood thickness – 15mm or 16mm would work provided there is enough bracing.

2) Exterior width to match XT1464 or plus a bit … 0 to 6 mm any more than that the box starts to look too big.

3) 455mm is as deep as I would go. If you set the horn back 30mm you can always cut a bit off (15mm) the front depending on how you do the grills.

4) “baffles. Right now, I'm thinking 15mm ply routed out 6mm, with a 6mm spacer ring” that would be a good compromise, alternatively make the baffle thicker (18mm) and route 10mm to 12 mm

5) “Corners....make the box square for simplicity and let any brave souls lop off corners” agree, and don’t forget to take all the screws out. It looks much better, smaller and more professional with the corners cut off, and slightly lighter. The corner piece only needs to be 12mm because the span is so short.

6) I would also make the top, bottom and back all the some width – easy to cut out and assemble.
 
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