Help with fomo - JBL 4645C Subwoofer

[sahil fardeen]

This thing is now flat to 20-25hz without any eq. And the difference it makes in movies is huge. Remember this is without any baffle wall/ 1 pi loading

 

[Rahan]

The red one is clearly not normal. Good job for your realization.

 

[sahil fardeen]

I am certain that this happened only after the recone process. Something may have went wrong, maybe some variance is T/S parameters. Before that although not as deep as this sub, it was better. But still, this Diy unit is bonkers. Flat to 20hz in room W/o any eq

The red one is clearly not normal. Good job for your realization.

 

[sahil fardeen]

@Rahan would it be possible to get a rew measurement for your sub, with and without B6, just to see how deep a “proper” 4645 should go, in room, without baffle wall?

 

[Rahan]

Yes I'll do it

 

[Rahan]

red stock; blue with 2 filters. both have 20 hz HP
. No smoothing.

 

[sahil fardeen]

red stock; blue with 2 filters. both have 20 hz HP
. No smoothing.
View attachment 465792

Okay. Thank you. That does go very low indeed. But not much difference with stock and dsp. Anyways- it indicates that my unit was defective

 

[Rahan]

I did not try without the 20hz HP filter. I guess it would go a bit lower. Definitely your unit was faulty. Enjoy your sub!

 

[rana_kirti]

Yes he will need a correction if he wants to go down to 20 hz. Without it you'll barely approach 30Hz. 2 sub won't change it.
sadly the XLS serie don't have speaker preset. Here what you have : PureBand™ Crossover Filter System:
The PureBand Crossover System provides a variable state Linkwitz-Riley 24dB/octave filter allowing you to choose a point between 30Hz and 3kHz on standard 1/12th
octave centers. Three filter types are available: Low Pass, High Pass and Band Pass

The PeakX
Limiters provide your amplifier and system with higher performance and better protection. They are specifically tuned to work with this amplifier design and
power-supply to achieve higher SPL with less audible artifacts while protecting your loudspeaker investment.

What does above really mean in regard to the XLS ? Without a external DSP it has no performance below 30hz ?

 

[rana_kirti]

Thank you all for help! Finally I bought today single CROWN XLS 2502 to power my 2xJBL 4645c subwoofers. Hopefully this will work fine

​

How did it go ? Is it a Good Subwoofer amp down to 5hz ?

 

[sahil fardeen]

What does above really mean in regard to the XLS ? Without a external DSP it has no performance below 30hz ?

XLS 2 has High pass filter (hpf) upto 30hz at the lowest only. Technically the 4645C plays down to 20hz in room so you are loosing a lot of output with the xls hpf set to 30hz.
You need an external dsp with 20hz HPF or something with builtin dsp like a crown xti.
You could use an xls without HPF but the 2242H driver looses steam quickly due to its limited xmax and you could destroy it (without an HPF) with as little as 60-100w

 

[sahil fardeen]

How did it go ? Is it a Good Subwoofer amp down to 5hz ?

There were multiple opinions, some with a notion that these amps have undefeatable HPF below 18hz. Some state otherwise.

 

[pauldavidthomas]

I have tried with both the XLS and the DSi ( 2000 Bridged ) chaulk and cheese. The XLS did nothing for the sub. The DSi has a setting ( EQ ) Specifically for the sub - totally different output. XLS does NOT work. DSi DOES work. These EQ settings are also available on other Crown amps.

 

[smygolf]

Might ad that CDI also works as a charm, have 2 of them bridged for 2 x 4645C

 

[sahil fardeen]

Well, months passed and i am still enjoying my DIY 4645. But the 2269 is luring me to buy it. It would be a significant upgrade- More than twice the xmax, higher sensitivity(actually is, below 80hz where we use it) and higher power handling, and considerably lower distortion.

Most of the LFE content is below 80hz, where the 2269H has a clear advantage, it equals 2242 at 80hz, and below that it increases rapidly, and at 30hz there is almost a 10db higher output (at the same input power) So technically 2269 is more sensitive than 2242, and should be a big big jump.

Here in india every harman products are relatively cheap compared to other countries, can get a brand new 2269H from authorised harman service center for $700.

Should i hit the upgrade bug and move on to 2269, in the same cab?

 

[Rahan]

.10 dB more output at 30 Hz? From what I see, it’s closer to a bit over 5 dB , which is already significant. I guess that for an LFE channel, the 2269H will clearly perform better. It’s a true subwoofer, whereas the 2242H isn’t. I was about to pull the trigger, but since we’re moving back to France, it’s not the best moment to do it. The 4645C cabinet works fine with the 2269H; it has already been done successfully.

 

[sahil fardeen]

.10 dB more output at 30 Hz? From what I see, it’s closer to a bit over 5 dB , which is already significant. I guess that for an LFE channel, the 2269H will clearly perform better. It’s a true subwoofer, whereas the 2242H isn’t. I was about to pull the trigger, but since we’re moving back to France, it’s not the best moment to do it. The 4645C cabinet works fine with the 2269H; it has already been done successfully.View attachment 493131

6db higher output with around 15db less harmonic distortion, if the distortion is equalled then the difference is almost 10db.

My bad. Fell for their strategy

 

[sahil fardeen]

Should i make the move? attractive is its xmax, considerably lower distortion and slightly more output down low.

Exactly the areas where 2242H falls short when compared to modern drivers with huge excursion

 

[smygolf]

Should i make the move? attractive is its xmax, considerably lower distortion and slightly more output down low.

Exactly the areas where 2242H falls short when compared to modern drivers with huge excursion

In EU 2269 has a contender in bms 18n862 and simulated it has the same perfomance as 2269 in 4645C cab
739Eur at toutlehautparleu

And if you want to build smaller cabs with the same/better performance- you have 2288
But the availabilitygoes up and down

 

[sahil fardeen]

In EU 2269 has a contender in bms 18n862 and simulated it has the same perfomance as 2269 in 4645C cab
739Eur at toutlehautparleu

And if you want to build smaller cabs with the same/better performance- you have 2288
But the availabilitygoes up and down

18n862 is almost 1000$ here in india and min order quantity is 2. I am a jbl fan and can get it for less makes it no contest

2269 can be had for $700