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    Posted: 08 June 2021 at 8:27am
Hi all,

Looking of upgrading my 8 x PD186 in vented enclosures to 18NLW4000 - anyone have any experience/feedback with this driver?

Aiming for a 400L enclosure tuned to 35hz or so, for 2x18". The xmax on this driver looks one of the best I've sim'd in this type of cab and allows for better use of the peak wattage than others which are xmax limited.

Amp power is limited to SAE PCM20s so about 3500w peak - not much use getting drivers above this power rating for the moment I'm thinking. Amps are always on 32a 3ph with their own 10 or 20 amp circuit/phase (FYI I've been able to get them to pull about 11 amps each on sub heavy content Smile)

Based on sims so far, it's 6db up at 38 hz from the G Sub, for a single 2 x 18" (after taking into account xmax SPL limiting).

Replacing all 8 would equal a theoretical 24gb of gain at 38hz across the 8 - seems like a pretty decent improvement.... 

One of the big factors in wanting to upgrade is the PD186 are getting a bit hot and flabby/higher impedance/power compression degraded towards the end of the night if we aren't onsite and DJs have smacking the limiter straight from open doors.

Cheers,
Jackson




Edited by vertx - 08 June 2021 at 8:31am
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 08 June 2021 at 4:48pm
Originally posted by vertx vertx wrote:


Based on sims so far, it's 6db up at 38 hz from the G Sub, for a single 2 x 18" (after taking into account xmax SPL limiting).

Replacing all 8 would equal a theoretical 24gb of gain at 38hz across the 8 - seems like a pretty decent improvement.... 


One new speaker 6dB up compared to the old one, will still make for the same 6dB up with all 8 new speakers compared to the 8 old ones.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vertx Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2021 at 5:36am
Originally posted by Peter Jan Peter Jan wrote:

Originally posted by vertx vertx wrote:


Based on sims so far, it's 6db up at 38 hz from the G Sub, for a single 2 x 18" (after taking into account xmax SPL limiting).

Replacing all 8 would equal a theoretical 24gb of gain at 38hz across the 8 - seems like a pretty decent improvement.... 


One new speaker 6dB up compared to the old one, will still make for the same 6dB up with all 8 new speakers compared to the 8 old ones.

I did think 24db seemed like a huge amount LOL

Disappointing... But when adding further cabs/drivers you gain an extra 3db, right? across all frequencies? in the passband?

Even a 6db increase at 38hz overall is a good result.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2021 at 9:01am
Note that doubling the amount of cone surface gives you 3dB extra, however total powerhandling doubles, which also gives you another 3dB extra. Thus a total of 6dB potentially when doubling drivers.

I would expect it to be around 5/6dB extra over the 186's with the 18NLW4000. That would mean you can get the same amount of SPL with only 4 cabs instead of 8 (with the 186's). Note that you need some good port design to get the max out off them. There is an interesting topic running right now, with some cool links --> http://https://forum.speakerplans.com/reflex-or-horn-loaded-subs_topic106286.html#1053347
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2021 at 8:31pm
Originally posted by vertx vertx wrote:


Disappointing... But when adding further cabs/drivers you gain an extra 3db, right? across all frequencies? in the passband?


From 4 cabs to 8 cabs (+100% gear) -> +6dB. That equals 4 times louder overall.
OR you only need 1/4th of the power and still go as loud as before.

Going from 4 cabs to 6 cabs (+50% gear) -> + 3dB. That equals 2 times louder overall.
OR you would only need half the power and it'll be as loud as before.

Now going from PD186 to 18NLW4000 might seem like a good plan on paper.
But both have somewhat comparable sensitivity figures, so in order to get that +6dB extra from a one on one swap, you need to feed about 4 times the power to get that +6dB out of them.
In real life use, that's not going to happen, because the 18NLW4000 will run a lot more into powercompression than the PD186.
The net result might be a meager 1 or 2 dB when all is said and done.
Just adding 50% extra PD186 cabs ( and powering each speaker the same as before ) plain and simple adds a solid +3dB overall, without strsssing any speaker/amplifier more than before and is going to be a lot less costly, compared  to replacing all speakers and seriously upping the required power to even get some SPL gain.
Food for thought ...
As always : your money, your gear, your decision Wink

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Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2021 at 10:25pm
@Peter Jan

I doubt the 18NLW4000 has that worse power compression figures.
A driver like the NLW400 has probably the same amount of coil area and a much more advanced cooling.
Let alone the possible SPL with transients would be enough for me. 
Good example of goinf from an old to a newer driver would be the SB218 vs SB28 from L'acoustics. 
Though the SB218 did not sound bad, the SB28 could/can replace two SB218's with a smaller VC driver.


@tc 
You could also look at comparable ferrite magnet drivers. To name a few: 18TBW100, 18HW1070 etc.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2021 at 2:01am
Originally posted by smitske96 smitske96 wrote:


I doubt the 18NLW4000 has that worse power compression figures.

When in doubt ... the power compression graph tells you the story.
-1dB @ 500W, -3,2dB @ 1000W and - 4,6dB @ 2000W.
On a side note : I wonder why so few manufacturers provide those graphs Embarrassed

Originally posted by smitske96 smitske96 wrote:

Let alone the possible SPL with transients would be enough for me.

Fair enough if the cost, time and effort for only that works for you.
Whether that or other gains for certain amounts of money, time and effort suits the OP ?
That's why I said : "food for thought" and "your gear, your money, your d...."

Originally posted by smitske96 smitske96 wrote:


Though the SB218 did not sound bad, the SB28 could/can replace two SB218's with a smaller VC driver.

That statement (initiated by L-Acoustics, I know...) is true by comparing the very, very first (~30 years old) SB218 (with LAB amps - Llc processors) versus the recent SB28 (with LA(X) amps - SB28 setting).
The difference in attainable SPL doesn't come all that much from using more recent/better speakers, but rather from the circumstances in which they work (amplification/processing).
Not saying better speakers aren't available these days, just putting things in perspective, that's all.
As always... your mileage may vary Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2021 at 2:21am
The real story will be in comparisons of the Bl(x) and L(X) curves for each driver… oddly enough, the small-signal T/S parameters are only a starting point for a design. That goes for the nominal sensitivity value, and all other free-air parameters too.

On the topic of high power, long term usage; the older PD drivers have an advantage of sorts when it comes to thermal compression due to the sheer bulk of the magnet, but I’d wager the NLW4000 remains better controlled and has improved ventilation when being driven with music.

Of course, using an optimised port and Class D amplifier with the modern drivers would be another step in the right direction.

Klippel data for the 18Sound should be available, if you ask nicely.

Edited by toastyghost - 10 June 2021 at 2:26am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2021 at 7:43am
@Peter Jan

The PD186 is from that same time IIRC. And something sticks with a topic a few years back where I saw the SB218 processing on a SB28 (they were almost identical). LA48 should still be no slouch against a LA8.

I would recommend the TS to buy one of the newer drivers, and build a test cab and compare to the PD186. If in the position to do some measurements, there are many ways to get some real numbers. And in that case I am still very confident that the 18NLW4000 or comparable will come out on top.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2021 at 8:21pm
The original poster said:

"One of the big factors in wanting to upgrade is the PD186 are getting a bit hot and flabby/higher impedance/power compression degraded towards the end of the night if we aren't onsite and DJs have smacking the limiter straight from open doors."

Rather than spending thousands of pounds on new speaker drivers that you don't need, why not employ a sound engineer to manage the event for the night to "stop the DJ's smacking the limiters from open doors".

If you think that the sound has been degraded by the end of the night, what about peoples hearing?

If you run a sound system you should be in control...not a load of idiots (DJs???) who obviously havent got a clue.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vertx Quote  Post ReplyReply Direct Link To This Post Posted: 11 June 2021 at 1:14am
I'd love to have the funds to get a tech onboard! Long term that might be feasible but this is our first install, it's a handshake agreement with some mates who have a not yet legal venue with two 300 cap rooms and we are doing it for pennies on the dollar for them because we want to be a part of a creative/artistic/cultural/music focus space in Sydney.

I'm thinking two things at this point after having a chat with a few people....

1) I can get the 18NTLW5000 so I might go 4 or so of those to start, do a few MDF prototypes with a big curvy L-Vent and see how it goes. We've been asked recently about doing a few more installs so if the new cabs/drivers are not showing a good enough improvement over the PD186 (I have a feeling they will), then they can go to the next install.

If they do show the improvement I hope, by the time I'm done with prototyping, I should have saved enough from gigs to get the other 4 drivers, at which point I can sell the PD186 or move them to another venue when we get the next install job.

2) Get a Levelizer from RC1 to so I can have a social life (still only 29!) and not have to stop in at the venue Thursday, Friday, Saturday LOL

I'm in a position to take measurements of the old and new subs so should be able to get some real world "in box" metrics as well as some subjective "how much stick can it take" comments from the crew.


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Post Options Post Options   Thanks (1) Thanks(1)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 11 June 2021 at 10:09am
The Leveliza is great for keeping things to a perceived volume level. Still, it is not a limiter nor a true automatic gain control like the Drawmer SP2120, Formula Sound AVC2, Outline SPL Control Plus, etc.

Think of it more like someone riding the fader, based on the 'full-range level of the system you set:
https://www.waves.com/plugins/vocal-rider#achieving-perfect-vocal-levels-with-vocal-rider

Most importantly, it doesn't really track the bass. If someone kills the mids and highs of the mixer, then cranks the hell out of it, your subs will still be ramming into the limiter of your DSP.

In the before times, we were one of the first adopters of the Leveliza and found them best on gigs to allow for single engineer stages to have relaxed changeovers, toilet breaks and the like. The prototype install version we had made with a tamper-proof cover instead of knobs did the same trick for a three-floor nightclub that has a single tech on site. No more wondering 'is upstairs being hooned?!' when you're stuck in the booth of the basement.

You get the best results for an unattended playback install by using both of those types of toys together or coding your own in something that's open architecture like a BLU London or Xilica Solaro.

I'd suggest you do that in steps anyway because it'll benefit new subs too if you make them.

Port shape optimisation is the subject of lots of research lately. I shared some links to papers in another thread. Just guessing won't necessarily give better results than a straight slot, and could end up worse!

It's also worth noting that Hornresp doesn't include nonlinear behaviour in the modelling as far as I'm aware. You'd want to use large-signal data like the Klippel vibration file for the driver in Akabak3 to see what happens at large signal levels. Or just cut some wood, and get some drivers and port shapes cut to audition.

Sub measurements are a funny thing though, so if you're going down that route make sure you have a massive car park or field to hand. Ground-plane, nearest boundary 7m+ away, mic 10m from the average acoustic centre (not the grille!) of the cabinet.




Edited by toastyghost - 11 June 2021 at 10:10am
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