New DIY Mid High (90deg) - AKA PM90

I for one would not change a single thing. Peter Morris has done more development work on these than most of us would do in a lifetime of speaker building. I feel that you would be opening a Pandora's Box in changing anything based on anyone's unresearched opinion.
 
Johannes Scholz said:
Hi everyone,

After reading this post, I'm very interested in building a pair of PM60/90 speakers, and Don has kindly sent me the latest plans.

I have two questions regarding the components and would appreciate hearing your thoughts.

For the horn:
What do you think about using the Limmer 292 horn with the BMS 4594HE? It could be an alternative to the RCF in the 90° version.

For the woofers:
This thread has mentioned the RCF MB12N351 and the B&C 12NDL76 as potential drivers.
What are your thoughts on using the in this design?

Looking forward to hearing your opinions!

Thanks and best regards,
Johannes
Click to expand...
Hi Johannes, I don't think the Limmer 292 will fit in the standard design? There has been a 14" variant of the PM90 (PMAK90) built in the US and I think it used the 250 (or may be 292 with a B&C 464 ) and it worked very very well.
The Beyma 12P80Nd/V2 looks like it would work very well .... similar to the 12N351
 
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Hello everyone,
Nice to read all the posts! Now I want to start building my own.
Can someone send me the CAD files and the latest plans for the PM90s?
Thanks you :)
 
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Not sure if the plans in post #316 are the latest, but they look complete.
D

Post in thread 'New DIY Mid High (90deg) - AKA PM90'

Re: New DIY Mid High

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...
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Post 913 of this thread has Peter's most recent PDF file of the build.
Max Warasila had done a great job with complete Cad files but I think its in the 60 deg thread. When I have time I'll look around for it.
 
I am about to retune my pair of PM90s. Two questions, therefore:
1. Somewhere in the thread, tuning the mids on groundplane was recommended. Should I lay them flat, so that both openings of the dipole are on groundplane, or just place them standing normally?

2. Regarding the procedure described in post #700, would this best be done a) measuring with pink noise and adjusting the phase graph in realtime using allpass-filters or b) with sweeps and treating only excess phase?

best wishes to you all!
 
wish i still had my boxes as i am more verse on the IIR tuning aspects of it all. flat or on pole i dont think there would be a major difference. its all about getting data without reflections. Or gating to maximize what you need to see..
 
morning all, My PM90s are for sale if anyone is interested. They consist of 2x12ND930 drivers and 1x BMS 4594. looking for around £1800 for the pair. They cost me £2700 to build, plus labour.

They've been used around a dozen times and sound incredible. I'm only selling due to size and weight as i want something a little easier on the back!

DM me if you're interested.

Based in central London, UK.
 
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I'm gonna be selling the drivers from my boxes if anyone is interested. seems the boxes are gonna be hard to sell as they are.

please DM me if you're looking for either 12ND930 or BMS 4594 drivers (includes crossovers)

they'll also be up for sale on ebay.
 
I would like to fly PM60-90 much higher in the air because many bigger events demand fly to cover the crowd.
The box is pretty capable and dont see the point to always keep it close to subs.
With that on my mind I have some questions..

*Is there way to get proper low end out of these boxes down to 75-80Hz. (One 60* or dual 120* per side, I already have subs up to 80Hz)
12p80ndv2, 15p80nd, 15mc700nd?
(I dont mind if box would be little bigger and heavier, anyway there are always sturdier stands available and what is more important is covering bigger crowd with same boxes without need for line array which is bloody expensive.)

*Less important but as understand with PM60 there is a few db higher SPL in HFs vs PM90.
Will PM60 benefit of additional dual 12" drivers positioned symmetrical to "back side" of box, dual 12"s opening facing each other at horn throat. (Of course box would be bigger and heavier in that case if even possible without compromising SQ).
 
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hey peter, thanks for your great work. looking forward to build a speaker soon based on the design.
only question is - which 12" driver do you use in your final design:
the RCF MB12N351 or the B&C 12NDL76
both are mentionted in your posts - the RCF in one of the very first posts and the B&C in your "PM90_current" schematics in post number 913...
i'm confused about that and appreciate your feedback
would like to build the speaker as you recommend most
respect the architect
 
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