SWR BigBen replacement woofer

#41
In 150lt, the Sigma 18" and the Kappalite 3015LF look extremely close (if not equal). It's a small cab for a 18" and a big cab for a 15".
I don't know if the 3015" can offer advantages apart from being lighter.
CostruireAudio sells on ebay and the listing says "will ship in 3-4 working days" or something like that. I tried hard to buy from an italian company but it's really hard.

3015.jpg
 
#42
Update: according to WinISD Beta, the original tuning of the cabinet is 77hz. Now, in this field I ain't worth the pinky finger of Steve Rabe but... it really doesn't make much sense.
The metal badge says "BigBen SUBWOOFER" but that tuning is probably barely good for a small PA cab. Anyway I don't know how it performed with the original woofer, maybe it was nice.
In its new form I've just made the holes for the Alpha 6CMBRA and the Ciare tweeter and I'm waiting for the Eminence Sigma 18" to show up on monday... then I'll re-tune the cabinet and will start making noise with it.
I've also put tilt-back wheels and rubber feet so it's very easy to move around.

IMG-20170623-WA0006.jpeg
 
#43
Your response curve is overdamped on both examples. Shortening the port depth will reduce the damping (increase the Q) in the transfer function. If you work out the numbers with the improved tuning, you will find that the response is pretty darn close to a subwoofer. This means looking at the large and small signal sensitivity versus frequency.

You can't automatically believe some of the numbers these programs deliver without considering the context of the overall system response. This is why "design by wire" that is so popular in the DIY community results in some truly awful sounding speakers (even though the "designers" exclaim how much better they sound than everything else in the world). It's important to understand how the SYSTEM aspects resolve, and using software without the understanding can lead to a false sense of security and bravado.
 
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#44
"The response is pretty darn close to a subwoofer" yes, but that's with a tuning MUCH lower than the original one. I don't have the TS parameters of the original BagEnd speaker to make a comparison but with such a high tuning, I wouldn't expect it to be ultra-solid under 40hz.

I honestly think I played thru enough cabs to recognize an "awful sounding speaker"... but with good woofers, it's not easy to make something that sounds "bad". Turning an average speaker into a beautifully sounding cabinet, that definitely takes experience, no doubt.
I know I don't have all the needed informations so I'm simply moving on with what I have and what I know. If I had a sense of security I wouldn't ask for advice here, I guess. :laugh:

Also seriously doubt that commercial speakers are all made with "excellence" in mind... I've played thru so many bad sounding cabs (in the 600-700 bucks range, not cheap) that can hardly be made worse by any deaf DIYer IMHO.
 
#45
Triad said:
"The response is pretty darn close to a subwoofer" yes, but that's with a tuning MUCH lower than the original one. I don't have the TS parameters of the original BagEnd speaker to make a comparison but with such a high tuning, I wouldn't expect it to be ultra-solid under 40hz.

I honestly think I played thru enough cabs to recognize an "awful sounding speaker"... but with good woofers, it's not easy to make something that sounds "bad". Turning an average speaker into a beautifully sounding cabinet, that definitely takes experience, no doubt.
I know I don't have all the needed informations so I'm simply moving on with what I have and what I know. If I had a sense of security I wouldn't ask for advice here, I guess. :laugh:

Also seriously doubt that commercial speakers are all made with "excellence" in mind... I've played thru so many bad sounding cabs (in the 600-700 bucks range, not cheap) that can hardly be made worse by any deaf DIYer IMHO.
Click to expand...
My experience is quite different than yours then. There are indeed some great drivers that are used in the wrong application because a designer is so focused on one aspect of the performance that they utterly fail to see the big picture. Then there are the guys so focused on crossover impedance linearity that they fail to grasp the basic concept of (leading) reactive loading to the amplifier (often causing serious damage to the amp). There were a couple of DIY examples here on TB that were responsible for shutting down well designed amps and blowing up others. Fortunately those are either gone or have been corrected.

Of course there are commercial speakers that suck, but I would have to say that the majority of "non-budget" commercial speakers are easily as good as you can design and build yourself if you count both time and materials. Times have changed from the "good 'ol days", the better manufacturers understand this and have upped their games.
 
#46
Uhm... I won't report the brands or the models, but I've played thru modern commercial speakers that had very weak lows and "honky" mids, or had a HUGE hole in the mids even if used standing in front of the cab,
had ridiculous volume or "crapped out" with normal 4 strings bass frequencies with waaay less than 50% of the power they were rated for, with flat eq. (at frequencies over 40hz and with a clean signal, go figure with a 5er!).
There are also well-engineered cabs that simply sound "meh", I owned or tested a few of them as well. 1000 bucks cabs.

You certainly know that not all the brands use "high-profile" solutions. Most of them simply put a decent, possibly light woofer (whatever the size) in a cabinet sized in a way they think makes sense (90% of the times too small),
a first or 2nd order high-pass filter with a cheap piezo or maybe a decent tweeter at the usual frequency (90% of the time it's 3500hz) and you've got a new product. :roflmao:
I see you're trying to put me on the right path by making me look at the "whole picture", but I also hoped to get "real life advice" to make this experiment fast and successful,
like "Tune it to 30hz for THIS reason instead of tuning it to 40hz" or "What you're doing will lead to speaker failure, death and pestilence". ;)
 
#47
Triad said:
Uhm... I won't report the brands or the models, but I've played thru modern commercial speakers that had very weak lows and "honky" mids, or had a HUGE hole in the mids even if used standing in front of the cab,
had ridiculous volume or "crapped out" with normal 4 strings bass frequencies with waaay less than 50% of the power they were rated for, with flat eq. (at frequencies over 40hz and with a clean signal, go figure with a 5er!).
There are also well-engineered cabs that simply sound "meh", I owned or tested a few of them as well. 1000 bucks cabs.

You certainly know that not all the brands use "high-profile" solutions. Most of them simply put a decent, possibly light woofer (whatever the size) in a cabinet sized in a way they think makes sense (90% of the times too small),
a first or 2nd order high-pass filter with a cheap piezo or maybe a decent tweeter at the usual frequency (90% of the time it's 3500hz) and you've got a new product. :roflmao:
I see you're trying to put me on the right path by making me look at the "whole picture", but I also hoped to get "real life advice" to make this experiment fast and successful,
like "Tune it to 30hz for THIS reason instead of tuning it to 40hz" or "What you're doing will lead to speaker failure, death and pestilence". ;)
Click to expand...

You sell the better modern manufacturers short, most are far more capable than you give them credit. Your generalizations are simply untrue from what I have seen actually working in the industry. Of course, you can only guess what real designers actually do, because if you were a real designer you would have immediately understood the specific advice that I gave you. Did you not understand it?

Since you already know it all, better that a real designer of coure, why did you even bother posting your questions to us mere mortals?
 
#48
Uhm... you're making me sound like an arrogant prick but honestly I don't think I'm behaving that way and if you got me wrong, might be my fault or maybe 50/50?
I guess you were lucky to only try well engineered stuff, but trust me, I'm not making this up. I'm not saying that those guys weren't able to build something better, I'm only saying that many commercial cabs are made that way.
Pretty easy to check, if you wanted to. Can't really see how you're taking this assumption in the wrong way.
I ended my reply with "but I also hoped to get "real life advice" to make this experiment fast and successful"... definitely not something I'd say if I was trying to present myself as an expert.
 
#49
Triad said:
I ended my reply with "but I also hoped to get "real life advice" to make this experiment fast and successful"... definitely not something I'd say if I was trying to present myself as an expert.
Click to expand...
And you did get some real life advice but promptly ignored it in your (apparent) quest to disparage modern commercial speakers and how you can't understand why your speaker is labeled a subwoofer.
 
#50
Get the latest free winisd pro. If looking at Eminence, many of their speakers have a build plan pdf that shows the individual speaker in several sizes of cabs. Those have full range graphs at the maximum safe wattage (usually). Winisd shows the full range, but it's not meaningful except at the lowest frequencies. The cab plans won't likely have a cab exactly the size of what you're after, but usually something close to get an idea. Then maybe don't argue with Andy. He's been in the industry since most of us were in diapers (the first time).
 
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#51
BadExample - I already have WinISD, both the Alpha (probably too many parameters for my limited knowledge) and the Beta. It's where the graphs came from. :)

For the Sigma, the Eminence has several "plans", the closest is this one:

"Med Vented Box, High Power, Med F3 By McJerry, Eminence Speaker LLC Displacement limited to 600 watts. Must use 24 dB per octave high pass filter set to 35 Hz or higher to protect driver from overexcursion. Place ports symetrically around driver if possible.

Box Properties --Description-- Name: Type: Vented Box Shape: Prism, square (optimum) --Box Parameters-- Vb = 4.5 cu.ft V(total) = 5.049 cu.ft Fb = 45 Hz QL = 7 F3 = 48.72 Hz Fill = minimal --Vents-- No. of Vents = 4 Vent shape = round Vent ends = one flush Dv = 4 in Lv = 9.805 in"

5cu.ft are 141 liters, the BigBen cab is 130 or so, so slightly smaller.

This is something I checked before I selected the Sigma over the other 18"s, they all needed a bigger enclosure to work properly.
 
#52
But they all don't need a bigger box to function well if you understand what is actually happening. This is what I have been trying to tell you. Your Big Ben box size is plenty big.

(I worked for the company that owned (and unfortunately shut down) SWR, so maybe I know a bit about this box ;) )

In fact, there are some extended performance 15" drivers that can be adapted to that box which in some cases might get more out of the box than an 18".
 
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#53
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#54
LOL thanks Passinwind, looks like I was "old-style" without wanting to :laugh:
The new version is nice... many many more parameters, the only "con" I can find right now is that it doesn't warn you if the air speed into the port is too high (the older version did).
I'll do some simulation here as well and will try to integrate the missing parts reading some articles online. Shouldn't be too messy, the impedance is high so no risk to shut the amp down, the crossover is already there... I only have to find a good compromise for tuning. :thumbsup:

I forgot to add that at a certain point I decided to go for Eminence 'cause it was the easiest brand to get for me. I wanted a Faital FH500 when I started but after paying for it, the ebay seller stated their Faital delivery was late and almost a week later they sent me a refund... so I had to change my plans.
 
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#55
Now a pretty technical question: I read that the maximum air speed in the vents is 34m/s... it's the limit I should have when using the maximum wattage of the woofer?
In this case, the woofer is rated for 650w. In 130lt, tuned at 30hz with one 14cm round vent, the air speed is 32m/s at 18hz or so, 36m/s at 18hz with 650w. Is it good enough, in pure theory?
My amp is rated for 500w/8ohm but the problem is, my basses go way lower than 30hz with their fundamentals.
 
#56
Triad said:
LOL thanks Passinwind, looks like I was "old-style" without wanting to :laugh:
The new version is nice... many many more parameters, the only "con" I can find right now is that it doesn't warn you if the air speed into the port is too high (the older version did).
Click to expand...

That warning was a bit pessimistic, but to address your later post, acceptable air speed margin is really a "just depends" deal IME and IMO. Even if you're using a low tuned ERB, some make lots more fundamental than others. IIRC WinISD allows adding EQ/filtering to the sim, which could impact your results quite a bit I think.
 
#57
Should I use the "Transmission line for port simulation"? Anyway I see the driver would go out of xmax on low even with 200w! Is it normal or I'm doing something really wrong?

For Agedhorse: Now I see why the cab was tuned that high, my bad! Something I couldn't check with the old version I was using.
 
#58
Post your new graphs.

Your port might be better if it was larger and ducted deeper.

One problem with higher air velocity is an added nonlinearity term to the system response equation.
 
#59
excursion.jpg velocityat500w.jpg

What parameters do you want me to show into the screenshot? So you think I should use a bigger port (bigger than 6")?
From what I see, I plan to start with 40hz tuning and move from there, eventually. I didn't want to mess with the original 6" holes 'til I really found the perfect solution.
There are plastic 6" ducts for ventilation, I'll buy a long piece on monday to start the experiment. What velocity would you consider high to the point of messing with the system response equation?
Sorry, definitely a lot of questions.
 
#60
Your hole is 5.5" and your velocity is on the high side, so moving to 6" would be good. Then you will need to tune the cabinet to the driver to get a system response by adjusting the depth of the port duct.

From 5.5" to 6" is a significant difference in area due to the squared factor.
 
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