Boomy JBL 4509 cabinets

[retro soulman]

Hello! I’m trying to setup my cabinets correct to have some better response but all I have is boomy sound and not much low end. The cabs are on stands but horizontal placed so the horns and tweeters are on ear level. The woofers are the stock 2035 (although I got 4 2205b to try). The system is active and the low end is powered by a crown cl2. I was thinking to fill the cabs with more material if that helps. I also block the top bass reflex but it didn’t help much.... the system is crossed at 560hz.

[Mike Caldwell]

Check the that speakers are wired correctly / polarity. Use a 9 volt battery and touch it across the speaker terminals and see the speakers both move in the same direction.
With those woofers positive voltage to the positive terminal will make the speaker cone move back.

What does it sound like using just one speaker sub cabinet?

How big is the room?

If you walk around in the room are there areas with more low frequency than others?

Are you using the one Crown CL amp to power both cabinets?

Are you running the amp in stereo with a cabinet connected to each channel?

Double check the input wiring on the CL amps, having a balanced input mis-wired on one
channel would cause a lot of cancellation between the speakers.

Check the speaker output terminal wiring as well.

[retro soulman]

Everything is correct wired. No phase issues with the bottom section (everything was kept original and never opened). Here are some photos of my system.

[RMC]

Hi Retro Soulman,

Boomy bass is a bizarre symptom in this case. Usually a product of too small cab volume and/or too high tuning. However in my view the cab may be too large! one reason low bass may be furtive, but that doesn't explain why the boomy sound, shouldn't be there with a too large box, and you already tried downtuning without success. On that specific aspect then i'd suspect some room issue Mike previously mentioned.

On the other hand, assuming the above shows nothing wrong, i'd look at this from a different perspective.

First, there's a thread here indicating the 4509 cab is the LF portion of the 3632 Cinema system, and called 3639 (confirmed by Tech Manual pic). I estimate box volume about 9 cu.ft, tuning about 40hz.

Second, JBL used the M115-8A woofer in the 3639 and later the M115H-1 it seems in that same box (see pic). You're using the 2035. I don't see the M115H-1 parameters in JBL's table but for the other two they are with the relevant numbers for box sizing and tuning:

2035H: Fs 48hz, Qts 0.34, Vas 140.5 L; M115-8A: Fs 46hz, Qts 0.39, Vas 225 L. Notable difference for Qts and Vas, both affecting proper cab size. In view of driver you use vs what JBL uses in the box my impression is the cab may be somewhat too large for 2035 use hence "not much low end." ?

Third, many bass systems are engineered for 2 Pi loading, meaning placement directly on the floor or in a large wall. Here its on stands, away from the floor therefore you don't get the full boundary LF acoustic reinforcement (no deep bass). The higher the stand is the more LF loss. Have you experimented with 1-2 boundaries (floor/wall)?

RE "I was thinking to fill the cabs with more material if that helps." Depends on the actual problem(s) you have, as well as the material you have in mind. If damping material, it creates virtual volume you may not need specially if the box is too large for the driver. If books, bricks or pieces of wood to reduce actual box volume it might increase boominess...

As for trying the 2205b in such box i don't see your situation improving bass wise, it could be even worst, i know since i have a pair of 2205H, and its low Qts 0.21 is a deep bass killer... The 2035 should do better assuming all is right. Are the 2035 really in good shape or might have an issue?

Richard

EDIT: Nice system you have. Has i anticipated your enclosures are pretty much off the floor, about a foot high...

8981989820

[retro soulman]

Hi Retro Soulman,

Boomy bass is a bizarre symptom in this case. Usually a product of too small cab volume and/or too high tuning. However in my view the cab may be too large! one reason low bass may be furtive, but that doesn't explain why the boomy sound, shouldn't be there with a too large box, and you already tried downtuning without success. On that specific aspect then i'd suspect some room issue Mike previously mentioned.

On the other hand, assuming the above shows nothing wrong, i'd look at this from a different perspective.

First, there's a thread here indicating the 4509 cab is the LF portion of the 3632 Cinema system, and called 3639 (confirmed by Tech Manual pic). I estimate box volume about 9 cu.ft, tuning about 40hz.

Second, JBL used the M115-8A woofer in the 3639 and later the M115H-1 it seems in that same box (see pic). You're using the 2035. I don't see the M115H-1 parameters in JBL's table but for the other two they are with the relevant numbers for box sizing and tuning:

2035H: Fs 48hz, Qts 0.34, Vas 140.5 L; M115-8A: Fs 46hz, Qts 0.39, Vas 225 L. Notable difference for Qts and Vas, both affecting proper cab size. In view of driver you use vs what JBL uses in the box my impression is the cab may be somewhat too large for 2035 use hence "not much low end." ?

Third, many bass systems are engineered for 2 Pi loading, meaning placement directly on the floor or in a large wall. Here its on stands, away from the floor therefore you don't get the full boundary LF acoustic reinforcement (no deep bass). The higher the stand is the more LF loss. Have you experimented with 1-2 boundaries (floor/wall)?

RE "I was thinking to fill the cabs with more material if that helps." Depends on the actual problem(s) you have, as well as the material you have in mind. If damping material, it creates virtual volume you may not need specially if the box is too large for the driver. If books, bricks or pieces of wood to reduce actual box volume it might increase boominess...

As for trying the 2205b in such box i don't see your situation improving bass wise, it could be even worst, i know since i have a pair of 2205H, and its low Qts 0.21 is a deep bass killer... The 2035 should do better assuming all is right. Are the 2035 really in good shape or might have an issue?

Richard

EDIT: Nice system you have. Has i anticipated your enclosures are pretty much off the floor, about a foot high...

8981989820



The low section is called 4639 and it's was produced with the 2035 woofers. The woofers are in perfect condition physical and mechanical

[retro soulman]

Hi Retro Soulman,

Boomy bass is a bizarre symptom in this case. Usually a product of too small cab volume and/or too high tuning. However in my view the cab may be too large! one reason low bass may be furtive, but that doesn't explain why the boomy sound, shouldn't be there with a too large box, and you already tried downtuning without success. On that specific aspect then i'd suspect some room issue Mike previously mentioned.

On the other hand, assuming the above shows nothing wrong, i'd look at this from a different perspective.

First, there's a thread here indicating the 4509 cab is the LF portion of the 3632 Cinema system, and called 3639 (confirmed by Tech Manual pic). I estimate box volume about 9 cu.ft, tuning about 40hz.

Second, JBL used the M115-8A woofer in the 3639 and later the M115H-1 it seems in that same box (see pic). You're using the 2035. I don't see the M115H-1 parameters in JBL's table but for the other two they are with the relevant numbers for box sizing and tuning:

2035H: Fs 48hz, Qts 0.34, Vas 140.5 L; M115-8A: Fs 46hz, Qts 0.39, Vas 225 L. Notable difference for Qts and Vas, both affecting proper cab size. In view of driver you use vs what JBL uses in the box my impression is the cab may be somewhat too large for 2035 use hence "not much low end." ?

Third, many bass systems are engineered for 2 Pi loading, meaning placement directly on the floor or in a large wall. Here its on stands, away from the floor therefore you don't get the full boundary LF acoustic reinforcement (no deep bass). The higher the stand is the more LF loss. Have you experimented with 1-2 boundaries (floor/wall)?

RE "I was thinking to fill the cabs with more material if that helps." Depends on the actual problem(s) you have, as well as the material you have in mind. If damping material, it creates virtual volume you may not need specially if the box is too large for the driver. If books, bricks or pieces of wood to reduce actual box volume it might increase boominess...

As for trying the 2205b in such box i don't see your situation improving bass wise, it could be even worst, i know since i have a pair of 2205H, and its low Qts 0.21 is a deep bass killer... The 2035 should do better assuming all is right. Are the 2035 really in good shape or might have an issue?

Richard

EDIT: Nice system you have. Has i anticipated your enclosures are pretty much off the floor, about a foot high...

8981989820
Here are the specs

[Woofer]

Have you ever had them set up vertically just on the floor without the 'stands'?

[retro soulman]

Have you ever had them set up vertically just on the floor without the 'stands'?

yeap. They play way better but the horns are too low bellow ear level. If I don’t find any solution I will place them again vertical unfortunately...

[RMC]

Easy solution then. Put the LF cabs directly on the floor (no base under), take that base or something similar and put it on top of LF cabs and put the horns on top of the base. You're done, the horns are now back to ear level.

Abracadabra!

[Woofer]

Easy solution then. Put the LF cabs directly on the floor (no base under), take that base or something similar and put it on top of LF cabs and put the horns on top of the base. You're done, the horns are now back to ear level.

Abracadabra!

Yep, that was gonna be exactly my suggestion too!

[RMC]

Hi Woofer,

Thanks for asking the question, the reply prompted me to suggest this simple fix. Sometimes we're too close to the tree and don't see the forest behind anymore.

Btw wife happened to see your Avatar pic on my laptop while writing and she liked the cat, nice! But then she likes them all, and is a "mom" for all little guys abandoned...

[Woofer]

That is my Bobby. A terribly handsome Tuxedo. He's gone now... but lives on thru' my avatars in the 'virtual world' out there somewhere..... I miss him heaps.

I tip my hat to your wife. What a fabulous thing she's doing. Wish there were more like her.

Anyway as far your problem is concerned, I hope it's fixed with what could amount to as a simple flip.
That base you already have, is obviously a bit big and unsightly, to add between the bass and horns, but at least try maybe even a milk crate to see if it's a 'fix', then you can make something accordingly afterwards.
Good luck. :)