New DIY Mid High (90deg) - AKA PM90

Re: New DIY Mid High

CNC wont be needed. Doesnt get any easier than this for DIY. Now if you want to assemble it yourself thats another story. I think Peter has done a fabulous job and I am happy to have seen this thread. I wish I could afford the original components but will build the cabinet regardless with the 12PE32's.
 
Re: New DIY Mid High

Which is the passive crossover option from BMS for the 4594? I could not find it on their website, is the frequency set or variable, and is it tried and tested to sound as sweet as bi-amping?
 
Re: New DIY Mid High

Peter Morris said:
I expect the 3TX will be similar to my double 10 and horn. It uses similar components and is a similar size and weight. This combination has been such a useful box for me and I'm sure you will be very happy with them :)~:-)~:smile:. In comparison the DIY12 should make about 10dB more output; but its heavier and bigger and requires more processing and amplifiers ... slightly different design compromise.

Love to know what you think after you have done a few shows with them.

Cheers

Peter
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Yes, I will definitely post 3TX impressions here. They have JTR's usual 30 day build window before they arrive.
The 3TXs were supposed to satisfy my itch for building your design, but I still itch like hell :lol:

Sooo...........I'm back IN ! Using the 950 horns and MB12N351s to make it easy to match everything.

It's really great, the additional work you and Don have posted. Huge thanks !
Please bear with some of my less than knowledgeable questions....hopefully they will help others along too, those who are learning as much as I am..

Cheers indeed
Mark
 
Re: New DIY Mid High

Don J Davis said:
Peter has given me the go ahead to post the project drawings. Bracing is something to be considered during the build. Add more as you see fit especially in the dbl 12 chamber.

I have opted for my own build to make the entire HF950 baffle removable via threaded inserts, using a gasket to seal it. This will allow better access to the chamber. As Peter stated, you don’t need to do that, the drivers can be installed through the HF950 cut out.

I have left off the pole cup position and side handles. Best to locate those yourself as you build.

There are no considerations in the design for flying the box. If you choose to modify it to do so, do it at your own risk.

If this box is like most DIY boxes I’ve made, some field adjustments will need to be made during construction. Please post any errors found, adjustments or improvements that need to be made and I’ll correct the plans.

If anyone wants the dxf/autocad file PM me.

Have fun, hope to see some progress photos soon!
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Hi Don, fantastic !! Many thanks !

Drawings read really clear !

I noticed you added part D to join the baffle plates together. I'm thinking to eliminate it and extend the baffle plates to join, like in your earlier drawings. Is there any reason not to?
And I see part C joins part B for a 15 deg angle (6.4+8.6). Is there any reason not to make them both 7.5 deg ?.....not that I can measure, let alone cut that fine haha
Oh, and this may be a question for Peter..... do the 60mm ports in part A need to be entirely pushed to the edge? I'm thinking to radius them.....

Are your threaded inserts for baffle removal going into the sides? Inserts into Part A look tough without some underneath blocking? Is that what looks to be an extra piece? (the small triangle underneath the 950 baffle / part a joint.)
Where will you use gaskets and what material?

Sorry for all the questions.......THX!
 
Re: New DIY Mid High

Peter Morris said:
You need to make the box as strong as possible so that it does not flex, but not use so much wood and bracing that it becomes too heavy .... I'm not sure you need the rear centre brace as shown but its defiantly not doing any harm. There also needs to be some bracing on the side panels. It would be best if you used a cross brace from side to side, but then you would not be able to get the 12” speakers in and out.

I gave all of this quite a bit of thought even custom making the pole mount to join the bottom of the box to the 12" enclosure, making it as strong and ridge as possible without adding weight.
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Do you know the weight of the 17mm ply you used? I'd like to get a sense of my expected total weight as compared to yours...figuring a box uses just short of 20 sq ft fully braced..

There are 3 thickness of baltic birch available here, very reasonably priced. 18, 15, and 12mm. They weigh about 2.6, 2.1, and 1.7 lbs/sq ft respectively.
I can also order Auraco 19mm at 1.63 lb sq ft, but the denser, more # of plies, BB is so much easier to make precise cuts with.
I'm hoping thinner and denser works as well as thicker and lighter....where's Young's modulus numbers when we need em lol

I'd like to use 15mm for the back, mid horn parts, and the12" and 950 baffles.
And 12mm for the sides and top/bottom...that would save 5lbs vs 15mm.
I'm hoping to use removable side to side braces in the horn chamber. Braces that could go in after the 12" drivers are mounted, before the horn assembly drops in...??
Thinking about using 5/4" closet rod of an equivalent cross sectional area rectangular stick. About 0.6 L in volume...

Speaking of volume...is it critical? Does concern need to be given to volume taken by handles and this brace idea?
I ask because i saw white suffing in one of your picts and i think i remember reading it is sometimes used to increase effective chamber volume...

Like I said to Don....sorry for all the questions...thx!
Mark
 
Re: New DIY Mid High

Mark Wilkinson said:
Do you know the weight of the 17mm ply you used? I'd like to get a sense of my expected total weight as compared to yours...figuring a box uses just short of 20 sq ft fully braced..

There are 3 thickness of baltic birch available here, very reasonably priced. 18, 15, and 12mm. They weigh about 2.6, 2.1, and 1.7 lbs/sq ft respectively.
I can also order Auraco 19mm at 1.63 lb sq ft, but the denser, more # of plies, BB is so much easier to make precise cuts with.
I'm hoping thinner and denser works as well as thicker and lighter....where's Young's modulus numbers when we need em lol

I'd like to use 15mm for the back, mid horn parts, and the12" and 950 baffles.
And 12mm for the sides and top/bottom...that would save 5lbs vs 15mm.
I'm hoping to use removable side to side braces in the horn chamber. Braces that could go in after the 12" drivers are mounted, before the horn assembly drops in...??
Thinking about using 5/4" closet rod of an equivalent cross sectional area rectangular stick. About 0.6 L in volume...

Speaking of volume...is it critical? Does concern need to be given to volume taken by handles and this brace idea?
I ask because i saw white suffing in one of your picts and i think i remember reading it is sometimes used to increase effective chamber volume...

Like I said to Don....sorry for all the questions...thx!
Mark
Click to expand...

[SUB]This is what I used - http://www.plyco.com.au/index.php?main_page=product_info&cPath=48_49&products_id=142

It’s not good timber, but it was cheap, light and reasonably thick and I was building a prototype. To get this project to work you need to keep the weight down.

19mm would make it too heavy; I think you could get away with 15mm everywhere with some careful bracing. I would not use 12mm. Can you get 5/8 of an inch ply (16mm) ?

I used some pieces of pine 19mm x 40mm on edge to brace the sides.

What I do as a crude test is tap or knock on all parts of the box (like you knock on a door). It should make a dull thud; if you feel or hear some resonance then you need to add bracing.

The box volume is not particularly critical in terms of handles and bracing.

Just double check the compression driver will fit between the two 12" drivers before you glue it together -- its very close in there.

@ Don ... the HF950 is shown 50 x 90 ... not 90 x 50 - no need to change it ... the horn mouth is square :)~:-)~:smile:[/SUB]
 
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Re: New DIY Mid High

Ossian Ott said:
Which is the passive crossover option from BMS for the 4594? I could not find it on their website, is the frequency set or variable, and is it tried and tested to sound as sweet as bi-amping?
Click to expand...

$25 each - http://www.assistanceaudio.com/assistance_audio_bms.html

They are very good ... but bi-amping the HF / VHF is slightly better, as is using the Lake and FIR processing. Bi-amping also offers better protection for the VHF. The 4594HE is also slightly better than the 4594

I use the crossovers in my double 10" and horn


also - http://www.thomann.de/gb/bms_c_16_16.htm http://www.thomann.de/gb/bms_c_16_8.htm
 
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Re: New DIY Mid High

David Chrapla said:
Peter what 10's did you use in that dual 10" design?

I forgot to ask when I was there.
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They use 18sound 10NMBA520 http://www.eighteensound.it/PRODUCTS/Products/CatID/8/ProdID=43#.VSIi92kiPq4

Originally the box used a standard compression driver and had a much higher crossover frequency. The reduced distortion in the mids as a result of the active impedance control was noticeable. Now they are using a BMS 4594 and cross at 650Hz I would choose a more powerfully 10" with a higher Xmax.
 
Re: New DIY Mid High

Mark Wilkinson said:
I noticed you added part D to join the baffle plates together. I'm thinking to eliminate it and extend the baffle plates to join, like in your earlier drawings. Is there any reason not to?
And I see part C joins part B for a 15 deg angle (6.4+8.6). Is there any reason not to make them both 7.5 deg ?.....not that I can measure, let alone cut that fine haha
Oh, and this may be a question for Peter..... do the 60mm ports in part A need to be entirely pushed to the edge? I'm thinking to radius them.....

Are your threaded inserts for baffle removal going into the sides? Inserts into Part A look tough without some underneath blocking? Is that what looks to be an extra piece? (the small triangle underneath the 950 baffle / part a joint.)
Where will you use gaskets and what material?

Sorry for all the questions.......THX!
Click to expand...

Sorry for the delayed response, been out of town doing a large Easter event.

Mark, ask away, I’m learning lots as we go too.

There is no need to have Part D if you don’t want it. Peter confirmed that before the drawings where released. I thought it might make the assembly easier and add a flat spot to mount the Speakon connectors in.

Yes, on the angles, you can use whatever you want, I just drew what the cad system suggested.

Yes, the ports need to be all the way to the edges per Peter. The adjacency to the horn wall adds length to the port depth. Also, Peter uses those as access to tighten some of the bolts on the 12s.

I plan to use blind inserts in that triangular piece of wood you spotted below the baffle. I didn’t detail it since I’m not sure how many people will build it that way. I do have an ulterior motive for the removable baffle too. I hope to be able to change out horns from the 90x50 to the 60x40 depending on the deployment. This would be done in conjunction with Peter’s design of the splayable version of the box. That way with a horn change the box can be used stand a lone or two aside. I haven’t gone much past the idea stage with this so far.

I haven’t chosen a gasket material yet. Something reusable and not to thick attached to bottom of the baffle. Some small pieces of wood will need to be installed like a ledge on the sides for it seal to as well. I’m a little concerned that the top edge of the HF950 may be very close to the front edge of the cabinet making it difficult to recess a grill if used. Per the plans there is 15mm offset but the HF950 flange is 13mm thick.
 
Re: New DIY Mid High

David Chrapla said:
The standard BMS I think will still cost about 750 each. The HE version a simple 1000 each. Something closer to 3-400 each for the CD is doable for me.
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Hi David, remember that through the group buy, the BMS will be discounted. Also, the HE version is only $35 more, not $250.
I know you will still have to pay shipping to Australia, but the cost will be down in the $500's, so closer to your budget stated.

Ivan Beaver said:
the 4593 ( a less expensive coax driver)
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The 4593 has a smaller slug of neo magnet for the HF, and it is inside the voice coil.
The 4594 has a much larger magnet, and it rings the outside of the HF voice coil. The difference in price is about $50.

Roy Novio said:
Nice work Don! OK who's willing to do CNC flat pack??? I'm very interested, thanks!:lol:
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What is "flat pack"?

Ossian Ott said:
Which is the passive crossover option from BMS for the 4594? I could not find it on their website, is the frequency set or variable, and is it tried and tested to sound as sweet as bi-amping?
Click to expand...

As noted below, the C8/8 or C16/16 are for the 4590, 4592, 4593, 4594, 4595, 4507, and 4508. And basically the only passive option from BMS.

On a related note, the link from Peter states an asymmetrical slope, 12 and 18 db/octave.
But I question this. There are three components, as seen in the pictures. Two caps, and one inductor.
It is my understanding that one cap would be 6 db/octave, and one cap one inductor would be 12 db/octave. Comments?
 
Re: New DIY Mid High

That would be my understanding on the XO also Jack but I do know that some simple second order XO's can be very complicated and outside the norm. SO not totally sure on the answer.

The 4594 if it cost 500 and the HE model 50 more than the HE will cost me 724aud before shipping. So my numbers are a bit off. BUT The CD's I was looking at are about half that cost. BUT I still havent decided yet on the CD. Once I get a few things off of my "to buy," list then I can maybe still go this route. BUT hopefully I will be able to do something during the group buy.

Roy I think Don had the CAD files and you could take that to a CNC and get a quote yourself.
 
Re: New DIY Mid High

You're right David thanks, anyone doing the mass buying from Assistance on the BMS 4594 CoAx? Not ready yet but I want to know time window from others so I can put my2 drivers in. Thanks!:)~:-)~:smile:
 
Re: New DIY Mid High

Hi Jack, AFAIK BMS are produced in Europe, would it be possible to participate in the group buy and get the drivers shipped from BMS to avoid extra costs due to the roundtrip to US? (I live in Sweden)
 
Re: New DIY Mid High

Klaus Zimmermann said:
hi folks - and TX to Peter for this excellent project :thumbup::thumbup::thumbup:
haven't read allpages, so did anyone sim the BMS 12n820? i got two pairs of them sitting around...
TX for any info
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Here is a plot of the BMS Vs the RCF. The RCF is the dark plot. The BMS was not quite as smooth as I liked. Its nothing do with the RCF being better, its just that it has more suitable parameters (BL and cone mass).
 

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