60 Degree DIY Mid Hi - AKA PM60

[Carl Klinkenborg]

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]

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]

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

 

[David Morison]

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.

 

[Derick Phan]

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]

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.

 

[Art Welter]

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!


Art

 

[Thomas J Russo]

what is the exit angle of the DCX354?

 

[Art Welter]

what is the exit angle of the DCX354?

From the cross section picture in the video linked above, looks to be around 5 degrees.

 

[Justin Kaiser]

Hello, do you guys think a Faital pro HF146 and a Faital LTH142 could be usable in a PM60?

 

[Art Welter]

Justin,

It is usable, but the 2.56" (65mm) diaphragm will run out of excursion at about half the perceived volume of the 12" drivers.
The 12" drivers can reach around 135+dB in the 650Hz crossover range.
According to the spec sheet, the Faital pro HF146 on a Faital LTH142 horn is displacement limited to around 124/127dB in that range.

 

[Agustin martin]

Hi

Anyone compare PM60 vs Tw audio T24?
T24 it’s powerful and cut is about 100hz also.

With sound and spl what is best?

Regards

 

[Art Welter]

I have not heard either, but the PM60 has a more efficient folded horn design, and a uses a co-axial mid/high compared to the T24's short conical front loaded 2x12" horn and 3" diaphragm HF driver, so it should achieve a higher SPL and sound cleaner than the T24.
The T24 from it's Fb at 73Hz to ~200Hz has about the same output as a front loaded 2x12" box.

https://twaudio.de/wp-content/-pdf_files/TW_AUDiO_T24N_Tests_Production_Partner_Reprint_T24N_EN-1.pdf

 

[Chris Burns]

Hey gang. On the hunt for 4 60 or 90 boxes. Preferred empty and unloaded.

Also, if anyone knows anyone in the US that can build 4 of them please let me know.

I’ve been out of the hobby for a while however just ran into someone who could really benefit from 4 of the 60s.

Thx!

 

[Don J Davis]

Hey gang. On the hunt for 4 60 or 90 boxes. Preferred empty and unloaded.

Also, if anyone knows anyone in the US that can build 4 of them please let me know.

I’ve been out of the hobby for a while however just ran into someone who could really benefit from 4 of the 60s.

Thx!

Hi Chris,
I have 4 of the 60 deg boxes in my storage I haven’t used in a long time. They are loaded with BMS 4594HE, Eighteen Sound XT1464 horn and 2 x RCF MB12N351. I can verify all that if you’re interested.
These are the boxes I built when Peter first started the thread.
I hate to part with them but I’d like to see them get used. I prefer to sell them loaded.
I’m in So. Cal.
Let me know if you’re interested and we can talk further email dj_davis8(at)h*tmail.com

 

[Derick Phan]

Hey all,

Finished a couple of these boxes and its sounding great already even without extensive processing time put in yet
However, I did not get the pole mounts under center of gravity correctly and both boxes are now tilted slightly up and to the side. I am finding out ways to remediate this and recall that there were some custom yoke mounts Peter setup. I don't have access to any metalworking/fabrication so it seems my option at this point is rather to have it stacked on top the subs.

Any ideas on other options to eventually get it on a pole? I may pick up some fixed tilt adapters which moves the COG slightly forward to try and remediate. I was also trying to look extensively for universal U-brackets for a pole mount akin to the yoke that Peter had, or similar to the T24N swivel bracket. Any ideas on this? I also recall there may have been some design for this where the penn-elcom handle placement had to be removed in order to incorporate this.

TW Audio seems to make a pole adapter for their swivel brackets, but I am having a hard time finding mounting U-brackets to incorporate and not sure if these HSF are widely available: https://twaudio.de/en/products/accessories/hsf/

 

[Jeff Babcock]

Hey all,

Finished a couple of these boxes and its sounding great already even without extensive processing time put in yet
However, I did not get the pole mounts under center of gravity correctly and both boxes are now tilted slightly up and to the side. I am finding out ways to remediate this and recall that there were some custom yoke mounts Peter setup. I don't have access to any metalworking/fabrication so it seems my option at this point is rather to have it stacked on top the subs.

Any ideas on other options to eventually get it on a pole? I may pick up some fixed tilt adapters which moves the COG slightly forward to try and remediate. I was also trying to look extensively for universal U-brackets for a pole mount akin to the yoke that Peter had, or similar to the T24N swivel bracket. Any ideas on this? I also recall there may have been some design for this where the penn-elcom handle placement had to be removed in order to incorporate this.

TW Audio seems to make a pole adapter for their swivel brackets, but I am having a hard time finding mounting U-brackets to incorporate and not sure if these HSF are widely available: https://twaudio.de/en/products/accessories/hsf/

Hi Derick,
Even if pole mounting is possible, I'm just not a fan of doing that with a box of this size.

My go-to instead for small gigs has been painter's scaffolding (the kind that has locking wheels and folds together all in one piece). Most home building supply stores such as Home Depot carry these. They are often bright colors - spray paint it all black.

It's sturdy enough to support multiple cabs, has room underneath for sub, and can be wheeled into place. You can also hang black fabric over it for a more professional look.

It's much safer and sturdier, and as a bonus they can be turned into rolling carts for load in and load out.

My 2c.
Cheers