60 Degree DIY Mid Hi - AKA PM60

Oct 25, 2018
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Bideford, Devon. UK
Derick, you cannot achieve 4-way stereo filtering on the DCX2496; I use two separate units in six-channel mono mode fed digitally by a DEQ2496, but my system is 5-way so I had no choice within my budget. Alternatively you can use the passive crossover for the BMS to make it effectively a 3-way system, or buy a 2-in 8-out crossover for 4-way. My PM90s (3-way) are fed using NL8s using doubled-up pins for the parallel 12" drivers and the (2-way) upper bass and subs are connected with NL4 cables with paralleled pins.
I would advise very strongly against using using cheap digital amps for the BMS - I use old iron and copper MC2 amps for these, and the improvement in sound quality over the Behringer is not insignificant - much more than just the icing on the cake, so to speak...
 

Jason Joseph

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Sep 27, 2011
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Agree with Carl on amps.
i used a simple 2 way topology for the pm60 using passive crossover. Less wires, wiring and amp channels. Should cost you less than $50.
using the full 3 way of course you can eek out the full performance of the box but then everything else becomes more expensive. And trust me the audience will not care.. :)
 

Derick Phan

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Nov 22, 2021
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Hello Carl,

Thanks for the clarity on this, although I am still a bit confused on the pinout of the NL8 connection (BMS VHF pins 4,4, BMS HF pins 3,3, mid 12NDL76 pins 2,2, Sub pins 1,1). Is this NL8 then going into a breakout panel in order to split the different pins into their respective channels for each amplifier?

Say for my use-case and Jason's example in a 2 way system for stereo tri-amp, I would have a single NL4 connector with the 2 12" paralleled on one set of poles and the BMS on the other pole then use a breakout cable to feed into two different amp channels? Or I would install two NL2 or NL4 connectors separately on the cabinet, with the 2 12" on one, and the BMS on the other connector into their separate amp channels. (For a stereo tri-amp system)

Is the difference here not just whether to have less cables split at the driver versus split at a separate breakout panel?

Thank you for the amps suggestions, I'll look into alternatives.

Derick
 
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David Morison

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Aug 21, 2012
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At the amp end of the cable then yes, a patch panel with the NL8 on it and individual cables to each amp channel is perfectly normal.

At the speaker end, you have a couple of options. First is to run separate cables to your subs from the amp rack - that gives the option of using heavier cable to better handle the high current needed by the subs. Your NL8 to the tops then only needs to use 3 out of the 4 available pairs, or you can put 2 pairs in parallel as Carl K describes which again gives better current handling for the feed to the 2x12's, as they do have the ability to take quite a bit of power between them.
If you really only want to run one cable out to each speaker stack from the amp rack then using NL8 for subs, 12's, upper mids and highs could be done - you could then either make up a splitter cable to get the sub feed out of that or put 2 NL8's on the subs and wire both in parallel, just using pins 1 for the sub and using the other connector as a pass-through to feed the rest of the channels up to the tops.

I'd favour the first option with separate sub cables, as that gives you the best current handling capacity and allows physical flexibility in how you set up ie it's easier to do centre clustered subs with separated L&R tops that way round.


PS: If you do decide to stick with the passive high-mid & high section, then you could just use NL4 for the tops with separate cabling for the subs.

HTH,
D.
 
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Derick Phan

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Nov 22, 2021
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Thanks David, that explains much of my confusion.

I will likely end up not creating a patch panel for convenience and keep each section on their own NL4 connector on the speaker end for separate cables on each section with 10-12 gauge wiring. I am assuming that keeping the 2x12's on their separate poles or wiring them in parallel will depend on the resistance and amp I provide during time of purchase. It seems the most efficient power-wise to get them on 8 ohms and wire in parallel to get down to 4, easy enough.

Cheers,
Derick
 

Rhys Edwards

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Jul 12, 2018
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Going back to the DCX464 vs DCX354 discussion, Bennett has recently released a video disassembling and showing the difference between them.

The main difference is in the diaphragm design with the 354 having a ridge allowing it to act as if it was a larger (than 3") diaphragm while also having decoupling effect at higher frequency to allow it to still have very high sensitivity. It's mentioned it's patent pending and appears to be first of its kind so direct comparisons to other 3" diaphragms isn't appropriate. I also exchanged an email directly with Bennett regarding the DCX354 in the PM60 box and the response was:

I think the DCX354 is actually better in this applications because it’s smaller, lighter, cheaper, and with that 650+Hz crossover point should have no particular output limitations. Of course if you really get into power compression the DCX354 will get ugly a little earlier, but its higher sensitivity narrows that gap, and anyway two 12” no matter how cleverly loaded in a single point source can’t hope to keep up. Maybe if you array a lot of them, but even two per side closely arrayed I wouldn’t think the DCX354 would be the output limitation.

Sounds like performance in the 300-650hz region should be indistinguishable between the two coaxials in when used in this box and is an appropriate application.
 
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Art Welter

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Jan 11, 2011
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Going back to the DCX464 vs DCX354 discussion, Bennett has recently released a video disassembling and showing the difference between them.

The main difference is in the diaphragm design with the 354 having a ridge allowing it to act as if it was a larger (than 3") diaphragm while also having decoupling effect at higher frequency to allow it to still have very high sensitivity. It's mentioned it's patent pending and appears to be first of its kind so direct comparisons to other 3" diaphragms isn't appropriate.
Rhys,

The Sd of the B&C DCX354 is larger than the estimations I had made previously which did not include the area past the decoupling rings , so the displacement assumptions made were incorrect, sorry for the errors!
DCX464, DCX 354.png

Art
 
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