conjuring deep bass from E145 in a huge enclosure

[johanwholst]

After playing with E145 for a while, I concluded that iit s my favorite driver despite lack any significant output under 50hz in my 140L (4.5cuft) test cabinets
Im now contemplating building cabinets at 300L net (10cuft) tuned to 30hz, a bit under the resonance frequency of 35hz. I am using a DSP solution.
Any reasons not to go ahead with this project? Can a cabinet for these drivers ever be too big (wife's opinion not included)?

[JoeNelis]

I say if your ears are happy go for it. thats what audio is about.

[johanwholst]

I say if your ears are happy go for it. thats what audio is about.

Sure, I really like what I'm hearing from E145 in a smallish 140l cabinet, but a box twice the size is quite a built, and I'm wondering how the large volume and relatively low tuning can affect the general sound and transient response of the woofer
Its not built in a day either...

[johanwholst]

This is my initial idea
Waveguide is M2, but I'm working on the idea of making the front baffle detachable for testing different horns

73299

JBL M2 as comparison

[srm51555]

Johan, sounds like it would be a cool build. Looking forward to see what you come up with.

[grumpy]

Everest went ~8ft3

http://www.audioheritage.org/html/profiles/jbl/everest.htm

[mantisory]

Looks like an interesting project. I currently have my 145's mounted in 4560 cabinets. I have them cut off at ~90Hz so I don't have to deal with the crazy response below that (the main reason, I think, that people dislike the 4560). Below that I use a Fitzmaurice THT :)
Anyway, I wonder what the difference would be, moving them from a mid-bass horn to a bass-reflex unit like this...I really like the way they sound now, but the could definitely use an asthetic upgrade ;)
Byron

[johanwholst]

Everest went ~8ft3

http://www.audioheritage.org/html/profiles/jbl/everest.htm

Okay, so I'm not totally off. Will probably end up with a net volume at 9cuft after some slight modifications and bracing.

Ill try to figure out a cabinet that's aesteticly acceptable, with good material utilization, and preferably modular if I can find a slick way of doing it.
Will use the same bracing structure as in M2 and most likely 1"mdf.

[Ruediger]

The E145 has these parameters:
fs = 35 Hz
Qt = 0.25
Vas = 275 liters

The 1st design which fits is a QB3 (Quasi Butterworth):
f3 = 62 Hz
Vb = 62 liters

The 2nd is a B6 and requires an electronic filter:
f3 = 35 Hz
Vb = 100 liters

The Qt of the E145 must be increased for a fit. The unwanted DC resistance of basscoil in the xover and in the cables can do that (if properly calculated).

Also you can use the above parameters as a starting point and vary them, see what results.

I do not have a design program, perhaps somebody with a program can run a simulation?

ruediger

[johanwholst]

The VAS in the JBL T/S is probably wrong, and I have seen claims that it should be 427 Litres.

[rusty jefferson]

The E-145 is the woofer used in the 801c coaxial driver used for the UREI monitors. The 813c and 815c have (I think) approximately 11/15 cubic ft boxes and helper woofers. I don't know if the crossovers in those models have a compensation to relieve the E-145 of low bass, but those speakers are quite (deep) bass shy unless soffit mounted (as designed) or heavily eqed (very common in the time they were popular). The E-145 is an amazing midwoofer. Keeping the boxes you have and building subwoofers may give more satisfying results?

[Ruediger]

The VAS in the JBL T/S is probably wrong, and I have seen claims that it should be 427 Litres.

427 Liters is about the value for the E155. Somebody should measure that :)

Anyway: using 427 Liters as the Vas for the E145 results in the following cabinet sizes:
for the Qb3: 96 liters
for the B6: 156 liters

ruediger

[Hoerninger]

An active filter can be found here on page 12/13
http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20%281972-05%20AES%20Preprint%29%20-%20Vented%20Loudspeaker%20A%20Restatement.pdf
and lots more of info.
__________
Peter

[Robh3606]

Hello

I have been using E-145's for years. They are a fine sounding woofer but they simply are not going to give you solid bass below 40Hz. I have used mine crossed at 80 Hz to subs. Mine are in 5 cubic ft, enclosures with 2235's under and it's a winning combination. The 2235's are in B380 clone cabinets as far as tuning with a BX-63 providing the LF boost at 26Hz.


Rob:)

[badman]

I agree about trying too hard with a driver not meant for deep bass. You'd be better off choosing a different option for the deep stuff- if enclosures that big are an option, perhaps multi-subs are instead? Multiple in-room subs proper distributes modal behavior better than single large enclosures, and will give you more output, deeper, with smoother response and higher output capability (and lower distortion) than you could ever hope to achieve with funky alignments.

Cost no option, Rhythmiks are very punchy, clean subs and would be great choices, but a nice benefit of multiple subs is the lowered requirements of each individual unit- you could go with inexpensive units from parts express, or DIY them. Audiokinesis also has a nice "swarm" sub arrangement though IMO it's overpriced at 3k, and I'd rather go with a few of these http://www.parts-express.com/dayton-audio-sub-1500-15-150-watt-powered-subwoofer--300-634 or their 12" brethren.

[mech986]

What's the difference between the E145 and K145 or K140? I'm not knowledgeable about the MI and Guitar drivers.

Personally, if one was to build a 9 to 12 cu ft box, I would submit that the 2245H or 2241/2242H would be much better drivers for low bass applications.

[johanwholst]

Well, with deep bass I'm referring to 30-35hz in room response.
I really like the sound of e145 as a wide range driver, and in my room it's way easier to place a big cabinet compared to adittional subs.
Been comparing these woofers to 2216nd and I'm actually prefer the e145 even the low end of equalized 2226nd in a M2 cabinet is amazing.
We will see what comes out of this.

[ivica]

After playing with E145 for a while, I concluded that iit s my favorite driver despite lack any significant output under 50hz in my 140L (4.5cuft) test cabinets
Im now contemplating building cabinets at 300L net (10cuft) tuned to 30hz, a bit under the resonance frequency of 35hz. I am using a DSP solution.
Any reasons not to go ahead with this project? Can a cabinet for these drivers ever be too big (wife's opinion not included)?

Hi johanwholst,

If You can accept that E145 driver Vas=427 Lit, then as any of bass box simulation program, You can see that using larger box would give You some improvement, but I would not suggest to tune the box under 40Hz, due to the cone displacement, so in such situation I would suggest to introduce sharp HF filter round 40Hz. May be the better results can be get using your box with the E145 in it, and make another larger box for 18-inch bass driver such as 2242, 2240, 2245, 2269 ...and introduce it as 'sub-woofer'.

regards
ivica

[Dr.db]

I´m on a project with an E-145 right now.
I´ll build 7,5 cubic ft. vented enclosures tuned to about 35-40hz.
There will be pictures and comments on my build in a couple of weeks located here: http://www.audioheritage.org/vbulletin/showthread.php?38804-Tribute-to-Lansing-Heritage-Forum

I have compared a 4,5 and 7,5 cubic ft. test-enclosure before.
In the small enclosure there wasn´t much going on below 50hz. In the huge box the E-145 took benefit and reached a little lower. But to put things right; the differences are not huge! But the enclosure size is :blink:

My experience told me, when located in the 4,5cubic ft box, it was best tuned to 45-50hz. This made a good output 50hz and up. When tuning this enclosure-size to 40hz, you will suffer a lot of efficiency between 50-80hz which really is noticeable.
The biggest advantage of the 7,5cubic feet enclosure was, that you really could tune the E-145 to 40hz without loosing to much in the midbass. But even in this beast of an enclosure, it is rather reserved in the lower bass.
It´s the nature of the driver, either people like it or leave it.
It has incredible punch, even in the big enclosure, but you will never get it flat to 40hz or lower without EQing.

[Ruediger]

Dr. dB,

can't you get in touch with an electronics guy who can do the measurements? You need a voltmeter, an amperemeter, a freuency generator and maybe a small amplifier. The two meters can be multimeters.

See figure 5 in the 1st Thiele paper on page 184. You need to measure a few points of that curve. The box can be one which you used for testing.

See page 203 in the second Thiele paper, top left. "The speaker is now placed in a vented box ..." This is how you should do the measurements.

Then there come some formulas about how to calculate Vas/Vb.

That's it.

ruediger

[Dr.db]

Hi,


I´ve allready started with the final enclosure, so there´s no way back to a smaller one.
Unfortunatelly I have no electrician around here...

[Loud & Clear]

I have a pair of JBL Cabaret 4628b's and they'll make the trip down to 30-35 cycles... :)

[more10]

If you don't care about playing loud, maybe a closed cabinet with Q=0.5 and a Linkwitz transform?

[toddalin]

If you have enough volume to play with, you can increase the bass by putting a 100 watt, non-inductive resistor in series with the woofer. This works because the E-145 has an impedience of about 60 ohms at 45 Hz, but only about 8 ohms above 100 Hz.

With the resistor the decrease in volume is about 0.5 dB at 45 Hz. But the decrease above 100 Hz is about 3 dB. So, relative to the overall sound, when you turn up the volume to compensate for the difference in volume of adding the resistor, you increase the bass at 45 Hz (and around it) by about 2.5 dB, and will hear a difference in the deep bass.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=61855&d=1397054088

[mech986]

Todd, what is the resistance of that resistor, you only stated the wattage and non-inductive character.

[toddalin]

My bad..., 8 ohms. More ohms will give you more bass but remove more overall volume.

[Ruediger]

Todd,

if you place a resistor in series with the bass, you increase Rg (generator resistance) and thus Qt, and that can make some more Thiele alignments available. So you can calculate these configurations properly.

But rather than putting a resistor in series you can build your crossover with affordable inductors, can built 3rd order filters (having two inductors) and can use affordable cables. The not-so-heavy wires will supply the resistance.

Ruediger