New DIY Mid High (90deg) - AKA PM90

Re: New DIY Mid High

Mark Wilkinson said:
Thanks for the further info!
I think I'll start trying to put together a cut list & layout.
Best, Mark
Click to expand...

The 12", horn and compression driver all just fit - make sure what you come up with will fit together. :)~:-)~:smile:

The compression driver sits between the spokes of the two 12" frames. Make sure you drill the hole to mount the 12" accordingly.

I will try and post some more pictures to help.
 
Re: New DIY Mid High

Hi Peter and all,
I've been following this thread with great interest being a DIY fan and having need for such a box. I'm willing to help with any drawings however I can. I've done 2D cad for years.

Peter, hope you don't mind, I took the liberty of drawing a scale version with actual components used based on your cut away view. I had to make quite a few assumptions so it varies somewhat from your drawing. It does clearly show how the HF driver will need to sit in between the spiders though.

The horn path looks different than yours. If you can give me its desired volume as well as the desired volume of the double 12 chamber I can refine things some. Any additional info or photos you have may be useful to me for drawing something closer to what you have actual have built. PM me or email dj_davis8 at hotmail

Don
 

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Re: New DIY Mid High

Awesome job!!

I think if you were going to place the big BMS between the spokes of the basket of the 12's you need to make sure you align the drivers so the spokes are out of the way. Also there would not be many options for other drivers to use unless they have the same basket design. Which is fine for this build. I was looking at using the 12PE32 woofers in another design and they would not work with their basket designs. Not a bad thing just a heads up for anyone using different drivers that are more available to them.
 
Re: New DIY Mid High

Don J Davis said:
Hi Peter and all,
I've been following this thread with great interest being a DIY fan and having need for such a box. I'm willing to help with any drawings however I can. I've done 2D cad for years.

Peter, hope you don't mind, I took the liberty of drawing a scale version with actual components used based on your cut away view. I had to make quite a few assumptions so it varies somewhat from your drawing. It does clearly show how the HF driver will need to sit in between the spiders though.

The horn path looks different than yours. If you can give me its desired volume as well as the desired volume of the double 12 chamber I can refine things some. Any additional info or photos you have may be useful to me for drawing something closer to what you have actual have built. PM me or email dj_davis8 at hotmail

Don
Click to expand...

That’s fantastic Don,

Now that you have drawn it to scale it immediately highlighted an error on my behalf :blush: – I have transposed one dimension incorrectly - 165mm should have been 135mm for the distance from the centre line to the start of the horn throat exit. The 75mm exit slot (horn mouth) from the speaker is in the centre of the driver. (I have wondered if it would cause any issues if it was not in the centre and I could make the horn slightly longer by moving the two horn mouths closer to the centre ??)

The gap in the middle of the two 12" drivers is also slightly more. This is achieved by machining off more of the corner as shown in my sketch in the post above. To make construction easy I made this part of the corner bend based on a 90 degree join also as shown in my above sketch. I also used more or less 3 pannels in this section of the horn, but you maybe able to get away with 2 has you have drawn. The volume in the enclosure needs to be about 35L - 40L.

To save weight and create a couple of hand lifting points I removed the panel in the centre of the back of the box.

Now that you have drawn it to scale it give a better impression of how space efficient the design is for a horn loaded enclosure, and much speaker power is packed into a relatively small space.

What I will do when I have a moment is print out what you have done and mark it up accordingly. (done)

Thank you Don, very much appreciated.
 

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Re: New DIY Mid High

Just looking at this Peter that brace is actually 2 pieces on each side so that the speaker frame can be accommodated, also the lower 2 port holes is only on 1 side of the horn mouth? Thanks!:)~:-)~:smile:
 
Re: New DIY Mid High

Here is an update based on Peter's response. I changed the horn panels to match more closely to his and refined some other details.
Basic volume calculations are as follows: (if my math is right)
Main chamber is 59.34 Liters before deducts for drivers and HF950. After deducts would be about 47.7L. I had to guestimate the 950 since there are no published specs on its volume. No bracing has been taken into account.
Horn paths: 24.83 Liters each. No bracing has been taken into account.
I've included some shading to show how volume was calculated. The interior width of the cabinet is 346mm.
Peter has truly managed to squeeze a lot into a small package.
I'll update it further once more info is available.
 

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Re: New DIY Mid High

Roy Novio said:
Just looking at this Peter that brace is actually 2 pieces on each side so that the speaker frame can be accommodated, also the lower 2 port holes is only on 1 side of the horn mouth? Thanks!:)~:-)~:smile:
Click to expand...

The 12's need to be a little further apart ....have to run will up date with some more info ASAP

Edit - with the prototype I left a space between the top and bottom 12" drivers mounting plates - then adjusted them to get them as closes as resonablly possible. The space between them was then filled in with a piece of timber about 25mm (1") wide - see picture. With the production model this is not necessary and it should be built as shown in Don's drawing.
 

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Re: New DIY Mid High

Don J Davis said:
There is room to push the 12's out to the edges of the chamber.
Click to expand...

Yes I think you need to do that ... I machined a lot more off the inside horn corner and made the radius bigger. That effectively made the panel thinner so the plate the 12 is mounted on could be a little wider and there was slightly more space for the 12s.

In addition there needs to be some bracing between the back of the box and the centre enclosure and the top of the box and the centre of the enclosure

....and thanks once again - fantastic.
 

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Re: New DIY Mid High

Peter Morris said:
Yes I think you need to do that ... I machined a lot more off the inside horn corner and made the radius bigger. That effectively made the panel thinner so the plate the 12 is mounted on could be a little wider and there was slightly more space for the 12s.

In addition there needs to be some bracing between the back of the box and the centre enclosure and the top of the box and the centre of the enclosure

....and thanks once again - fantastic.
Click to expand...

Excellent! Thanks Don and Peter!

I've been out beginning to gather quotes on the RCF drivers and horn. Also looking at the B&C 12NDL76 in case the MB12N351 proves too difficult....although I'm wondering about basket fit.....

Just to help remind any who are thinking about making this project a go.....please don't forget about Jeff's very kind offer in post #216 to facilitate a group buy for the BMS 4594HE....

Hey Peter, quick question...what's the purpose of the 10mm speaker spacer?
 
Re: New DIY Mid High

Mark Wilkinson said:
Excellent! Thanks Don and Peter!

I've been out beginning to gather quotes on the RCF drivers and horn. Also looking at the B&C 12NDL76 in case the MB12N351 proves too difficult....although I'm wondering about basket fit.....

Just to help remind any who are thinking about making this project a go.....please don't forget about Jeff's very kind offer in post #216 to facilitate a group buy for the BMS 4594HE....

Hey Peter, quick question...what's the purpose of the 10mm speaker spacer?
Click to expand...

The 10mm spacer is to stop the cone hitting the speaker mounting plate. The mounting plate is just a flat piece of wood with a 75mm x 250mm slot. See below

...and yes the B&C fits ... just... in fact everything just fits, even the 12 through the horn cut out.

Both speakers sound very similar, with a slight edge to the RCF - pushed hard, and depending on how low you cross things the extra Xmax of the B&C may be an advantage ... if you don't need the Xmax then the RCF would have the advantage - slightly better sound quality and slightly more SPL.
 

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Re: New DIY Mid High

Hi Peter,
I worked up the construction drawings for the box based on all the info so far. I wont release anything without your review, approval, this is your design and project and I really appreciate your generosity in sharing it with us. Let me know if you want me to email a PDF to you.
Don
 
Re: New DIY Mid High

Peter Morris said:
The 10mm spacer is to stop the cone hitting the speaker mounting plate. The mounting plate is just a flat piece of wood with a 75mm x 250mm slot. See below

...and yes the B&C fits ... just... in fact everything just fits, even the 12 through the horn cut out.

Both speakers sound very similar, with a slight edge to the RCF - pushed hard, and depending on how low you cross things the extra Xmax of the B&C may be an advantage ... if you don't need the Xmax then the RCF would have the advantage - slightly better sound quality and slightly more SPL.
Click to expand...

Thanks Peter, and Yes...pics Really helped !
I think I've found the RCF drivers.

Now if anybody knows were to get the HF950 horn in the U.S. ?
 
Re: New DIY Mid High

Mark Wilkinson said:
Thanks Peter, and Yes...pics Really helped !
I think I've found the RCF drivers.

Now if anybody knows were to get the HF950 horn in the U.S. ?
Click to expand...

FWIW I bought the horns from Team Audio in France - http://www.teamaudio.fr/en/
The RCFs I imported from England - http://www.thomann.de/gb/loudspeaker_12_inch.html
And the BMS from the US - http://www.assistanceaudio.com/
All of these companies provided excellent service, but I would especially like to thank Jack Arnott at Assistance Audio for his help.
 
Re: New DIY Mid High

If these plans get uploaded I am going to build this for my mains also. BUT I will be doing a poor mans version. So I will use the 18 Sound horn and 1480 or possible 1480A CD. Then use some 12's from BC such as PE32's or something around that price. If I use everything you used I will never get these built. I would like to eventually get the BMS but just too dear for me.

I still have to finish off my Othorn and now FLH subwoofer design.:D
 
Re: New DIY Mid High

David Chrapla said:
If these plans get uploaded I am going to build this for my mains also. BUT I will be doing a poor mans version. So I will use the 18 Sound horn and 1480 or possible 1480A CD. Then use some 12's from BC such as PE32's or something around that price. If I use everything you used I will never get these built. I would like to eventually get the BMS but just too dear for me.

I still have to finish off my Othorn and now FLH subwoofer design.:D
Click to expand...


For this design to work you really need to get the MID / HF crossover point below about 800Hz, preferably more like 700Hz. That’s why I have used the BMS, its 2– way design can go low and sound sounds fantastic.

There is no reason why you could not use another compression driver, but I suspect the output would compromised. The 1480 is only recommended to 800Hz.

The divers that look interesting are the Radian 950 (1.4”) and RCF 850 and 950. I do however have a couple of spare 18 sound 1480’s if you want to try them. If you want to save a few $$$ you could just use the standard 4594 with a passive crossover.
The18sound XT1464 is probably a slightly better horn than the RCF but its only 60 degrees. The XR1490C from 18sound is a little bit small if you want to go below 800Hz. The XT is usable down to 500Hz, the XR only 800Hz.
I have done a SIM with the 12PE32, it looks like it would work very well, but the output will be limited.

It will like the RCF still need a DSP correction.
 
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