Sub-woofer #4

[Robh3606]

I purchased a pair of 136H's with fresh re-cones in October finally got around to cutting some wood on the cabinets. Nothing special just another B 380 clone to add a second sub to the LFE channel. Should help with the more challenging movies.

Rob:)

[Lee in Montreal]

Subscribed :applaud:

Is the 136h a 2226 with a different cone more suitable for deeper bass? If so, how does it differ from the sub1500?

[Allanvh5150]

Older version of the 2230's series I think. Used in L300's etc.

Allan.

[Lee in Montreal]

Older version of the 2230's series I think. Used in L300's etc.

Based off the 2226 basket?

[Allanvh5150]

I have a feeling they will be ALNICO's. The cones are probably the same spec as the 2235 which fits into the 2225 frame but not the 2226.

Allan.

[grumpy]

Rob should respond, but the "H" suffix would be ferrite, the recent recone
-likely- means it's now a 2235H (cone/coil/mass-ring/spider).

http://www.audioheritage.org/vbulletin/showthread.php?10667-136H-2231H

Definitely -not- a 2226 derivative. SUB1500 being a completely different animal.

[Allanvh5150]

What is the deal with the brown cone?

[grumpy]

flash can significantly exaggerate small color shifts.

[Allanvh5150]

probably true. :)

[Earl K]

http://www.lansingheritage.org/images/jbl/catalogs/1979-comp/thumbs/page08_small.jpg (http://www.lansingheritage.org/images/jbl/catalogs/1979-comp/page08.jpg)

- Should be the consumer version of the 2231H .

<> :)

[pos]

there also is a 136HS that is a totally different animal altogether:
http://www.audioheritage.org/vbulletin/showthread.php?29626-136HS-stripped-naked
http://www.audioheritage.org/vbulletin/showthread.php?21554-Building-a-136HS

used in the synthesis 15" sub:
http://www.jblsynthesis.com/ProductDetails.aspx?prdid=39

recone kit model number is C8R136
quite confusing...

there even is a 2235H-1S !

[doyall]

there also is a 136HS that is a totally different animal altogether:
....
there even is a 2235H-1S !

S = shielded (as in the magnetic field is shielded from interfering with CRT video screens)?

[pos]

I thinks its S as in Synthesis
Those systems are made to be used in home theaters with video projectors, so I guess a shilded subwoofer is not really needed :dont-know:

[Allanvh5150]

S = shielded (as in the magnetic field is shielded from interfering with CRT video screens)?

I think if you want to get a 2235 that close to a CRT you are going to have more problems with the CRT falling apart than with colour problems.

Allan.:blink:

[Robh3606]

Grumpy is spot on they are essentially 2235's with the fresh re-cones. They came out of a pair of junker L300's that were parted out. Got the cabinet together now I have to add some Delta-dB dampening compound to help stifen the box up. It's neat stuff and easy to use. Just trovel it in and brush it around.

Rob:)

[Robh3606]

Put in the Delta dB so I can fiberglass the cabinet and see if the tuning works out. Should be 26Hz last one came in about a 1/2 Hz off. Can't wait to see what a pair sounds like for LFE.

Rob:bouncy:

[Lee in Montreal]

Just curious. What's the purpose of laying fiberglass in the cabinet? ;)

[Robh3606]

Hello Lee

It does a couple of things, it helps absorb any high frequecy output from the back of the cone and also adds virtual volume to the box. When I calculated the internal volume I didn't acount for the volume taken up by the woofer, bracing and the port. The fiberglass adds volume and effectively cancels out the space of the woofer bracing and port. Works very well. I will know if I got it right as soon as I run an impedence curve on the box. The minimum should be at 26Hz which is the target box tuning Fb.

Rob:)

[svollmer]

Put in the Delta dB so I can fiberglass the cabinet and see if the tuning works out. Should be 26Hz last one came in about a 1/2 Hz off. Can't wait to see what a pair sounds like for LFE.

Rob:bouncy:

Good thread!

Can you tell me where you purchase the Delta dB? I looked on the net and didn't find a source.

[Lee in Montreal]

Rob, my question about fiberglassing the enclosure may have sounded pretty, pretty stupid and now I realize it. I thought the black stuff in the picture was some sort of "fiberglass/epoxy", hence my question. Now I realize it is " Delta-db coating" for which I just made a search...

http://www.coatingsolution.com/products/sound_damp/delta_db.php

So, it all makes sense now. Damping the interior of a cabinet with fiberglass or foam panels (my prefered method) does "enlarge" the volume and decreases reflections. But that I already knew. I just got confused... :D

[grumpy]

Funny. There was a brief moment where I thought the fiberglass ref was re a fiberglass/gel coat too :) like the Altec Stanley Screamers product.

[macaroonie]

Funny. There was a brief moment where I thought the fiberglass ref was re a fiberglass/gel coat too :) like the Altec Stanley Screamers product.

Now that rang a bell but onset dementia prevents me from remembering. Please remind me Grumps

[Robh3606]

I just got confused... :D

LOL Yeah you had me wondering why you would ask that:confused:

So I put in the fiberglass closed them up dropped the woofer in and did a low power sweep to see what the Fb was. I just love this box design software came in at 26.1Hz. In any case I might get to fire it up tonight.

I am going to try driving a pair of amps off a single BX-63A. Just going to use a Y connector and try flipping the Imp switch to the mid setting. Let you know how it works out.


25.1189 7.6715 -5.3027
25.5859 7.6410 -3.3327
26.0616 7.6267 -1.3665
26.5461 7.6299 0.7583
27.0396 7.6580 2.7827


Rob:)

[Mr. Widget]

So I put in the fiberglass closed them up dropped the woofer in and did a low power sweep to see what the Fb was. I just love this box design software came in at 26.1Hz. In any case I might get to fire it up tonight.Hi Rob,

After talking with Dr. Toole and the rest of the Harman gang during my recent visit, they really drove home to importance of multiple subs in small rooms,(Small rooms means a residential space as opposed to a large commercial venue.)I have to say I am now a believer... seeing and hearing is believing. I am sure adding this sub will make your room sound much better.

What box program is it that you are using?


Widget

[Allanvh5150]

Interesting that multiple subs are now coming to the fore. I thought it was a normal thing to do so I incorporated 4 2235's into my room when I built it. That was a few years ago now and I can honestly say that I have not found any issues with them.

Allan.

[badman]

It does a couple of things, it helps absorb any high frequecy output from the back of the cone and also adds virtual volume to the box.




So, it all makes sense now. Damping the interior of a cabinet with fiberglass or foam panels (my prefered method) does "enlarge" the volume and decreases reflections. But that I already knew. I just got confused... :D

I have to disagree here: a cabinet loading the driver has 2 effects- it shifts the Fc upwards (From Fs), and the Qtc is shifted upwards (From Qts) in the same manner. Damping does not lower Fc back down, as it would be in a larger cabinet, but it DOES lower Qtc. In overstuffed cases, it can actually RAISE Fc. So stuffing should not be overused, as it can throw alignments off. None of that is a concern in this case, where the main function is to prevent leakage of higher frequency components through the vent, and the stuffing is just a modest lining of the walls.

For the most part, you can follow the rules of thumb (medium stuffing of a sealed cab, and lining the walls of vented) without having the enclosure effects make too much difference, it's heavily stuffed cabs where you start seeing the issue. The lowering of Qts is not entirely a bad thing- you get more deep bass output at the cost of output near Fc due to the slower rolloff. This is particularly useful in undersized cabs.


At least, that's my understanding. I'm a stickler for some things like this. One could build properly sized sealed cabs then stuff the hell out of them and lose a goodly chunk of their bass. They'd have been better with light-medium stuffing to kill internal standing waves.

[Robh3606]

What box program is it that you are using?

Hello Widget

I am using Bass Box Pro and the data sheet for the 4" Precission Port. The data sheet has a formula for port lenght and when all is said and done the port should be 1" longer than the calculated length. When you do it in Bass Box using a double flared port it comes in exactly 1" short. So the two back each other up. Using just Bass Box in the past on my 4344 cabinets the measured numbers came up right on target.


I am sure adding this sub will make your room sound much better.

Well one things for sure with a pair of B 380's a pair of Le-14 subs and E-145's the amount of air being moved is incredible. Talk about room lock! You put on the opening credits scene in Serenity or any part of Cloverfield and you can actually feel the air movement against your skin. I have to readjust the levels with the added sub which I didn't do last night just for kicks and it was Wow!

Well I can move the 4rth sub around a bit. The other 3 are basically locked in their positions. The BX-63A has no issues driving both sub amps. I think I am going to stick with the Imp switch in the center position. I also want to drag out my Synthesis Sub EQ and see what it can do.

Rob:)

[4313B]

Nice Rob!


Interesting that multiple subs are now coming to the fore. I thought it was a normal thing to do so I incorporated 4 2235's into my room when I built it. That was a few years ago now and I can honestly say that I have not found any issues with them.Simply revisited. Way back when the L212 first hit the market it was immediately discovered that more than one B212 could dramatically improve system performance and JBL made it available separately.

Since that time it has been common practice to use multiple subs, be they B212's, B380's, B460's or the myriad models that have followed.

[badman]

Nice Rob!

Simply revisited. Way back when the L212 first hit the market it was immediately discovered that more than one B212 could dramatically improve system performance and JBL made it available separately.

Since that time it has been common practice to use multiple subs, be they B212's, B380's, B460's or the myriad models that have followed.

Revisited and expanded- traditional explanation was "More output GOOD!" AFAIK, whereas in more recent years we've seen the use of distributed subs for modal management.

I say both are true- true 4 or 5 location sub setups are awful hard for real-world rooms, so sometimes people can only get the multisub modal benefit in a very limited way by using "stereo" subs, but also gain extra output. I currently use 4 subs, but they're stacked in pairs so it's more like my "stereo" example. Even that gets a raised eyebrow from my VERY beautiful VERY understanding wife. Hell, it's at the threshold of my own tolerance.

[4313B]

whereas in more recent years we've seen the use of distributed subs for modal management.Modal management was always the goal. We did have a grasp on the situation even way back then. Some people have merely put a multi-million dollar spin on it. Good for them! :p

[badman]

Modal management was always the goal. We did have a grasp on the situation even way back then. Some people have merely put a multi-million dollar spin on it. Good for them! :p


Fair enough!

For what it's worth- not sure that anybody's making millions on distributed bass :)

[4313B]

For what it's worth- not sure that anybody's making millions on distributed bass :)Spent on R&D... It's a joke.

[Robh3606]

I was resetting some levels and got to actually measure a 6db rise with the second sub added. I was hoping they were close enough for mutual coupling to work and in fact they are. This works out better than I had hopped as I can back down the gain to both and only run them at 1/4 the power levels of before for the same SPL. Now unless I get stupid I never clip out the driving amps which was an issue with just the one LFE sub.

Rob:)

[Allanvh5150]

You can never have too many subs, Rob!

Allan.

[rdgrimes]

If your electric bill is $500 and the drywall is falling off in the listening room, you might have too many subs.

[Allanvh5150]

If your electric bill is $500 and the drywall is falling off in the listening room, you might have too many subs.

It is! And?

Allan. :)

[DS-21]

I say both are true- true 4 or 5 location sub setups are awful hard for real-world rooms,***

But one of the benefits of multisubs is that each one needn't be a monster, so it can be possible to fit several subs into a room.

For example, I just upgraded the subs in my current living room. (See "modest multisub" thread in the DIY section of AVS for the old setup, which sounded and measured great but had three visible subs in the room. I used Geddes' setup methods. There will also be a writeup on the new setup, once I get time to do it.)

The total cabinet volume of the new subwoofer set is actually much more, about 95L compared to 70L previously), but because the subs were designed for the room there is not a single millimeter of subwoofer visible.

The main sub (a 65L closed box with an Aurasound NS12-794-4A, powered by a Dayton 1kW rack amp) is inside a piece of furniture (a cheap HOL chest from Ikea, modified with a cushioned fleece top to provide our kittens a place to sit and look out the window) in a front corner.

One of the secondary subs (a 15L closed box with an Aurasound NS10-794-4A, powered by an NHT A1) is inside a basket on a bookcase shelf.

The other secondary sub (a 15L closed box with a Peerless 830452 XLS10, powered by an NHT A1) is inserted inside the coffee table. (The coffee table is off to the side, so as to not provide reflections from the audio system.)

As far as output, I've not (and have no need/desire to) measure their maximum output, but the sims suggest >110dB from 25Hz up based on the efficiency of each cabinet, xmax of the drive-units, and amount of power on tap.

[Allanvh5150]

Indeed. I have 2 pair of 2235's in 2, roughly, 270 L boxes. 1000 watts on each box. I am lucky because they are built into the walls so they occupy no floor space.

Allan.

[Robh3606]

I am lucky because they are built into the walls so they occupy no floor space.



You guys are both lucky. I have big boxes in the open. Don't have much choice because of the layout and where they work best. It would be nice to drop them behind the walls.

Rob:)

[Robh3606]

Now that I have a pair of them I can dig up the Synthesis Bass EQ I grabbed off Ebay a while back. I finished making a rack box for the "control side sub", now I just have to wire it all up and see what the EQ can do.

Rob:)