Subs, what to do if you lack excursion?

[Art Welter]

Re: Subs, what to do if you lack excursion?

OK, so I just leave the plenum open for the full length then?

The plenum is "wasted space" in a ported cabinet, but allows fitting four cones in the existing cabinet shell.
A plenum open for the full length would be wasting internal volume that can be used as port volume, which is why I drew the cabinet design with the ports in the center.

 

[Spenser Hamilton]

Re: Subs, what to do if you lack excursion?

The plenum is "wasted space" in a ported cabinet, but allows fitting four cones in the existing cabinet shell.
A plenum open for the full length would be wasting internal volume that can be used as port volume, which is why I drew the cabinet design with the ports in the center.

So you could theoretically make all four "chambers" connect to the central port, and calculate port volume as being 4x the volume required for one driver.

 

[Per Søvik]

Re: Subs, what to do if you lack excursion?

Yeah, I've got it now. I had the impression that the plenum/slot provided acoustical resistance at low frequency and was actually playing a role in the tuning.

 

[Uwe Riemer]

Re: Subs, what to do if you lack excursion?

Yeah, I've got it now. I had the impression that the plenum/slot provided acoustical resistance at low frequency and was actually playing a role in the tuning.

Per,

leave this project alone, youve got not enough volume available.
The EV MTL4 Art mentioned has about 50% more volume than your box and drivers with stronger motor.

I did some sims with hornresp, all what you get is a huge narrow spike around 60Hz and a corresponding spike in group delay of about 30ms and these calculations are based on cold drivers.


If you seriously insist using these Omega Pro drivers, then simply tune the existing enclosures a little bit higher

Uwe

 

[Per Søvik]

Re: Subs, what to do if you lack excursion?

Per,
leave this project alone, youve got not enough volume available.

I know, it is a bit tight on the volume side. My other option is of course to sacrifice half the drivers and build something isobaric, but that would of course not solve the lack of excursion issue, rather the opposite. Maybe I should just get rid of them, but I thought I would give it a go. By using twice the drivers, I effectively double the excursion limit of each cabinet, and as long as the volume still allows me to reach that limit within the thermal limits of the drivers, the seemingly terrible response curve is of no real consequence. I hope ~:-D~:grin:

 

[Art Welter]

Re: Subs, what to do if you lack excursion?

So you could theoretically make all four "chambers" connect to the central port, and calculate port volume as being 4x the volume required for one driver.

That connection would be an increased port length, which would lower tuning and reduce cabinet volume by a huge amount.

Four chambers, four ports.
One chamber, one or more ports.

 

[Art Welter]

Re: Subs, what to do if you lack excursion?

Per,

leave this project alone, youve got not enough volume available.


Uwe

Uwe,

The MT4 has more external volume than Per's box, but the much larger manifold uses up a lot more internal volume than the plenum space I specified.
The Eminence sim in #13 is pretty close to 1/4 the volume of a 2x2x4 foot box that the OP has.
Banging kick bin.

 

[Craig Hauber]

Re: Subs, what to do if you lack excursion?

Uwe,

The MT4 has more external volume than Per's box, but the much larger manifold uses up a lot more internal volume than the plenum space I specified.
The Eminence sim in #13 is pretty close to 1/4 the volume of a 2x2x4 foot box that the OP has.
Banging kick bin.

Hi Art,
I too am "blessed" with a pile of these drivers. Would your sim work in stand-alone small cabinets or is it assuming the "plenum" type combination of 4 in one cab?
Getting to sore and bad joints to be carrying dual-18's or MTL type boxes by myself. Looking for something smaller that I can stack many multiples of to get the same effect as few large cabinets and thinking the "kick-bin" idea would work well for me.
(Regional use only for my own bar-band type shows)

I've been banging these drivers around in the Bassbox software and thought I was doing something wrong as they just don't want to go deep, which is odd considering how loose the compliance of the cones feel.
Since I'm used to older keele type bins and 18" EV loaded "sub scoop" type boxes I don't feel I would really miss the 45Hz and below range too much

 

[Uwe Riemer]

Re: Subs, what to do if you lack excursion?

Uwe,

The MT4 has more external volume than Per's box, but the much larger manifold uses up a lot more internal volume than the plenum space I specified.
The Eminence sim in #13 is pretty close to 1/4 the volume of a 2x2x4 foot box that the OP has.
Banging kick bin.

It was a pleasure to read the old data sheet of the MTL4, these guys really wanted to provide information.
The large plenum of the MTL4 creates the second resonator, it is part of the design and not wasted space,

the slot you designed resonates to high and has a total radiating area of about 880sqcm ( 7,6cm x 116cm ) or less,

the total Sd of the drivers is about 4500sqcm, looks like severe compression to me, I am curious if the cones will survive this

Uwe

 

[Art Welter]

Re: Subs, what to do if you lack excursion?

Hi Art,
I too am "blessed" with a pile of these drivers. Would your sim work in stand-alone small cabinets or is it assuming the "plenum" type combination of 4 in one cab?

The sim for a single driver cabinet is by Jerry McNutt, an Eminence designer. I don't even own the program Jerry uses, I use Hornresp for simulations.
I included it because four of these could nearly fit in each of Per's 4 x2 x2 foot enclosures.
Per was the first to mention the MT4, I simply showed him a combination similar.
To cram four 18" into one of his cabinets requires the use of a plenum, or mounting speakers on either side of the cabinet, not good for most stacking arrangements.

Low Xmax drivers are routinely loaded in horns with 3 or 4/1 compression ratios.
Although the plenum I suggested appears to have the "mark of the beast" compression ratio of 6.66/1, since the plenum unloads directly rather than being loaded on to a long air column as in a horn, I don't share Uwe's concern as to cone destruction.
As far as Uwe's statement that " the large plenum of the MTL4 creates the second resonator", I think if he models the chamber, he will find the plenum resonance well above what we find in this century to be a sub's useful band pass ;^). You can see it's primary contribution at 200 Hz in the frequency response.

When Dave Gunness designed the MT4 system, the idea was to cram as many drivers in small boxes as possible, with as little collateral sonic damage as possible.
The MT4 system could out scream Clair's S4, Turbosounds's TMS-3, Meyers MSL-3, my H-38/L4 system and most anything else I recall at the time.
In the mid 1980s after loosing in a direct shoot out to the MT4, I changed my L4 design from an offset horn load to a "V" shaped plenum/BR hybrid to "keep up with the Joneses".

The manifold quad driver mid/high in the MT4 system results in too much throat distortion at high levels, but the LF and low mids are still pretty viable, other than the usual Hoffman's Iron Law restriction, low, loud, small-pick two.
Back when records were vinyl, there was little LF below 50 Hz in most pop music, so a small, loud bass cabinet that dropped like a rock below 55 Hz was largely accepted.

Art "Mr.History" Welter

 

[Per Søvik]

Re: Subs, what to do if you lack excursion?

To cram four 18" into one of his cabinets requires the use of a plenum, or mounting speakers on either side of the cabinet, not good for most stacking arrangements.

Since a sub is pretty much omni anyway, I guess I could easily use 5 of the six faces and cram in 8 or 9 drivers ~~:smile:
Guess it would be nice and loud above 100 Hz and be perfect for my son's bass rig along with a 8KW amp and a suitable preamp (probably a non-valve job because of the good vibes it woud have to endure). 150 dB bass rig anyone? ~:-D~:grin:

 

[Craig Hauber]

Re: Subs, what to do if you lack excursion?

The sim for a single driver cabinet is by Jerry McNutt, an Eminence designer. I don't even own the program Jerry uses, I use Hornresp for simulations.

Good, I'm going to go with it then. Currently the drivers are loaded in a huge box close to 9cu ft and they just flop wildly if you get careless with EQ or overall levels. I'm fine with it but very hesitant to let anybody else use it. (This is all my leftover klag up here in ND&MT, all the modern rigs are working down in SoCal still)
I'm actually having fun making leftover and discarded PA gear sing again, folks up here are appreciative of quality for a change.
Unfortunately I'm stricken with such a bad arthritic joint condition I can barely walk sometimes so grovelling around with big old PA boxes is now out of the question. My tops are EV 12" & DH3 rectangular cabs that would work well for small gigs with a similar sized smaller sub.

As far as Uwe's statement that " the large plenum of the MTL4 creates the second resonator", I think if he models the chamber, he will find the plenum resonance well above what we find in this century to be a sub's useful band pass ;^).

That's what I thought too but was being polite

You can see it's primary contribution at 200 Hz in the frequency response.

I do remember crossing them quite high by modern standards, but still not that high!

When Dave Gunness designed the MT4 system, the idea was to cram as many drivers in small boxes as possible, with as little collateral sonic damage as possible.
The MT4 system could out scream Clair's S4, Turbosounds's TMS-3, Meyers MSL-3, my H-38/L4 system and most anything else I recall at the time.
In the mid 1980s after loosing in a direct shoot out to the MT4, I changed my L4 design from an offset horn load to a "V" shaped plenum/BR hybrid to "keep up with the Joneses".

The manifold quad driver mid/high in the MT4 system results in too much throat distortion at high levels, but the LF and low mids are still pretty viable, other than the usual Hoffman's Iron Law restriction, low, loud, small-pick two.

I still have many warm-fuzzy memories of mixing on that rig (had 16 stacks all crown MA3600, 2400, 1200 and PSA-2(!) powered. Many times I would deploy 16 subs with only 8 tops but do some judicious boosting at 40Hz to give more of a deep-bass feel with the 2-to-1 sub ratio allowing you to do it without beating the 18's to death. (and at that time I was just hoping the "new" EDM craze was just a passing fad!

Back when records were vinyl, there was little LF below 50 Hz in most pop music, so a small, loud bass cabinet that dropped like a rock below 55 Hz was largely accepted.

I still think that you can do really good sound with a rig that goes to 50. Everybody seems obsessed with 30Hz and below yet don't seem to care about the other 7 octaves. Amaze people with a quality band, a stellar mid/high mix and a fat-yet-proportional 55 to 120 and nobody will miss that 30Hz. (I've even witnessed this after running a club for 2 years)

Art "Mr.History" Welter

Thank you Art, your posts are always informative and interesting.

 

[Caleb Dueck]

Amaze people with a quality band, a stellar mid/high mix and a fat-yet-proportional 55 to 120 and nobody will miss that 30Hz.

Unless they hear the same band/tracks side by side with two types of subs. Mid-bass without sub-bass seems "old fashioned" in a bad way. I'd rather have subs that cleanly play deep and lack some SPL, than lots of SPL but not real deep.

 

[Per Søvik]

Re: Subs, what to do if you lack excursion?

Unless they hear the same band/tracks side by side with two types of subs. Mid-bass without sub-bass seems "old fashioned" in a bad way. I'd rather have subs that cleanly play deep and lack some SPL, than lots of SPL but not real deep.

To some extent you can have both, as long as the cabinet is tuned in such a way that it is tight at low frequency, you can use eq settings to either leave it loud and high or make it quiet and deep. Going for loud and deep will of course rip it apart ~:-D~:grin:

It has been my experience that if you don't do DJ/EDM stuff, you get judged only on the ability of the kick to smack your chest, and hardly anything else is of consequence as far as subs go.

 

[Art Welter]

Re: Subs, what to do if you lack excursion?

" You can see it's primary contribution at 200 Hz in the frequency response. "

I do remember crossing them quite high by modern standards, but still not that high!

The MT4 system had it's crossover points at 160, 1600 and 8000 Hz.
160-200 Hz was fairly common for low to low mid crossover region then as were fixed point processors designed for the system.
The high crossovers meant the bass cabinets also had to be raised up high for clean low mid sounds.

I used Brooke Siren FDS 340 four way crossovers back then, if you wanted to change the crossover point you had to solder in new components on little plug in cards.

 

[Craig Hauber]

Re: Subs, what to do if you lack excursion?

Unless they hear the same band/tracks side by side with two types of subs. Mid-bass without sub-bass seems "old fashioned" in a bad way. I'd rather have subs that cleanly play deep and lack some SPL, than lots of SPL but not real deep.

Of course side-to-side even tone-deaf drunks can tell the difference (thanks to the car-sub industry) but is sub 40Hz capability needed for a good show? (I personally don't think so) When given a choice between underperforming rig with deep subs or just solid "bass" output but no deep-bass I'll take the latter

Keep in mind I still consider mid-bass 120Hz and up and the bass from the "subs" 45 to 120. Anything lower is bonus and won't be refused ~~:smile: but I never had problems with not enough LF when mixing on MTL-4 rigs, in fact had a bit of a reputation for shaking things up with what the old dogs (at the time) considered "too much"

(Now here in eastern MT and west ND, peavey FH1's is considered a "sub" and yet have still heard some fine sounding shows by local "bar bands")

 

[Ivan Beaver]

Re: Subs, what to do if you lack excursion?

Of course side-to-side even tone-deaf drunks can tell the difference (thanks to the car-sub industry) but is sub 40Hz capability needed for a good show? (I personally don't think so) When given a choice between underperforming rig with deep subs or just solid "bass" output but no deep-bass I'll take the latter

Once you have heard subs that ACTUALLY go low (without having to boost the low end) it is REAL hard to listen to "normal" subs. The lower freq response gives a whole new depth and fullness to the sound.

I find that people who make the argument that you don't need to go below 40Hz have never actually used subs that go below 40Hz or heck that are even flat to 40Hz.

So they don't know what they are missing. McDonalds is just fine-until you eat a real hamburger-THEN you know the difference.

There are LOTS of normal music styles that require the extra depth. As soon as the 5 string bass shows up on stage- you BETTER have a sub that goes a lot lower-or you are not doing his music justice.

People put those lower freq in the music because they want the listener to HEAR it. If they didn't want you to hear it-then why put it in?

 

[Per Søvik]

Re: Subs, what to do if you lack excursion?

Once you have heard subs that ACTUALLY go low (without having to boost the low end) it is REAL hard to listen to "normal" subs. The lower freq response gives a whole new depth and fullness to the sound.

I find that people who make the argument that you don't need to go below 40Hz have never actually used subs that go below 40Hz or heck that are even flat to 40Hz.

So they don't know what they are missing. McDonalds is just fine-until you eat a real hamburger-THEN you know the difference.

There are LOTS of normal music styles that require the extra depth. As soon as the 5 string bass shows up on stage- you BETTER have a sub that goes a lot lower-or you are not doing his music justice.

People put those lower freq in the music because they want the listener to HEAR it. If they didn't want you to hear it-then why put it in?

The thing is, "needing" a sub that goes linear to 16 hz and delivers 140+ dB of tight undistorted bass is a need that most of us just can't satisfy. Too costly, too heavy and too bulky. If your budget is limited, what else would you give up to satisfy the need? I do agree that you really need a system that are able to do justice to a 5-string B or C bass, but is it reasonable to expect the same chest thumping we sometimes go for with the kick? When making EDM, and you put a little extra subharmonic on the bottom C, is it reasonable to expect that this can always be reproduced in a live outdoor setting? Should one really expect to reproduce the big pipe sub counter C from a church organ in any setting?

 

[Caleb Dueck]

How much compromise in reproduction is too much? If it's the difference between ideal bass vs "show doesn't happen", then 50Hz at minimal SPL is fine. I say it's up to us to raise the bar. Rather than "the way it's always been" vs "unnecessary extra features", it should be "recommended/normal" vs "compromised".

Small church last week, 2x EAW dual 15" subs, forget the model, end of their useful lifespans. This was their old "normal". I took a single, underpowered DBH-218, and watched collective jaws bounce off the floor. Their is their new normal. Lower cost and higher performance than what they were considering. Raising the bar, while often lowering cost.

 

[Tim McCulloch]

Re: Subs, what to do if you lack excursion?

The thing is, "needing" a sub that goes linear to 16 hz and delivers 140+ dB of tight undistorted bass is a need that most of us just can't satisfy. Too costly, too heavy and too bulky. If your budget is limited, what else would you give up to satisfy the need? I do agree that you really need a system that are able to do justice to a 5-string B or C bass, but is it reasonable to expect the same chest thumping we sometimes go for with the kick? When making EDM, and you put a little extra subharmonic on the bottom C, is it reasonable to expect that this can always be reproduced in a live outdoor setting? Should one really expect to reproduce the big pipe sub counter C from a church organ in any setting?

I think Ivan is forgetting his primary advice: "It Depends."