Compact Bass Bottom : Len Moskowitz

I believe that the Peerless driver is no longer in production. However, if you want a ready-built cab with similar specs, check out Acme's Low-B1.

Alex

 

I read this article a few years ago and it inspired me to build a 1x8. I really like the sound of it but it has two drawbacks. 1) it isn't very loud (duh, it's a 1x8) 2) it isn't efficient.

Both stem from the fact that it uses a woofer that's about 92dB efficient and onlyl handles 150 W. I've also noticed some heat induced efficiency drop - as the voice coil heats up, the resistance increases and it bassically gets less efficient. I push it pretty hard for what it is - a hifi woofer.

Len's article uses a similar 10" I don't recall the efficiency, but it's close. Again, it's a hifi woofer and just not designed to be played that loud for extended periods. I don't know how he ended up being so happy with it.

But the midrange is especially grand. It is smooth and detailed (it should be, it's a hifi speaker) but doesn't go extremely high. I think the upper limit is about 6khz, so it would be best to cross over to a piezo tweeter. Only issue is that would be alot more efficient than the other two speakers in the cab - you might not like the balance.

If I had to do it over again, I would start from the ground up. There's a ton of good MI drivers out there, Eminence, Selenium, JBL, EV, etc. that you can use. They're priced decently, and can handle the power and abuse a B string will dish out (in the right cab of course) Check out some of Bgavin's threads, and the cabinet 101 thread or whatever it's called. There's usually two or three threads going on box design (hey mod, any chance we could get our own forum?)

So, 10 years ago that was probably a good project, now I think you can do alot better from the ground up. WinISD is a great little program, it's free, and there's lots of help here.

One other thing - unless you want something unusual in a speaker, a used Avatar or Genz Benz cabinet will probably get you more speaker for the money than building your own. But it's a great way to spend a couple of weekends! That counts for something.

Stay Low,

Basstrader

 

The low SPL and efficiency points are well made. If you don't have much amplifier power, these points are more important than frequency response. Sort my spread sheet first by the ("USE") column, then in descending order on the efficiency column ("n0") or the Calculated SPL, then pick a driver from the top of the "4-string" or "5-string" list. Notice they are all JBL, E-V, B&C, or PAS drivers. These drivers are expensive, high quality, and high efficiency.

If you have power to spare, you can build something small that goes down low, but sucks lots of power. I have a tiny 1x10 cabinet glued up now for this purpose. It is 0.54 cubic feet net internal volume with a slot port for one of my Rockford 10" subwoofers. External dimensions are 20.75 x 11.0 x 12.0, and it will fit underneath my JBL E110 1x10 of the same size, as a tiny bi-amp pair. The cabinet is all assembled except for the baffle board.

The 10" Rockford performance is a pitiful 85 SPL and draws a maximum of 500 watts. I figure it is good for a maximum of 110 SPL at full power. However, it is tiny and will go all the way down to the bottom range. It should be perfect for a very small or low volume venue.

 

I split my cabs to either side of the stage. A pair of 1x15 + 1x10 on each side. I stand on stage left, and my conga player is on stage right. We can both hear it, and the sound at the audience position is more central to the band as a whole... very non-localized. I also play a Hammond through this rig, so the organ is spread across the entire stage.

I like to have a variety of cabs that I can mix 'n match for a gig. The teenie 1x10 sub will be great for a teenie gig. My rack is bigger than the new sub.

Another compact solution is the Omega Pro 12 in 1.23 cubic feet. It is only good up to 1,200 Hz, so you will need something else for the highs. This driver has a small delta between 43 ~ 89 Hz, meaning it is pretty flat in the low octave.

 

Found another thread to hijack since we have a couple of these threads going in pertuity, and it didn't really fit with my "rediscovery" of the Extended Bass Shelf alignment. Bruce finds all these threads anyway.

Been reevaluating, thinking. I currently don't have a biamp capable rig, but I've decided that might be where I want to go. I've also decided that the small space heater route is the more practical approach to getting there. Sorting and resorting Bruce's spreadsheet until we get down to Fb no higher than 31 Hz, F3 no higher than 40, Xmax > .3", max calculated spl at least 115db, Vb < 3ft^3 a couple of drivers fall out the bottom of that gauntlet. Mostly Rockford Fosgates (OHMYGOODNE$$) and one conspicuously inexpensive driver. The Dayton 295-120. Not terribly loud, but decently so with decent power handling. 2.9 ft^3, -3db @ 37 Hz, -5db @ 31Hz, 275wrms @ 8 ohms, max spl 116db, xmax is 8mm, all for the princely sum of $77. I'm suspicious though - the slope of the $/(Hz*db*Vb) curve is pretty constant.

If you're biamping you can make up for efficiency differences with power. In any case two 295-120's looks like a decent match for one B102, and the whole stack is no taller than my nephew. I may have missed a few gems in the spreadsheet - I threw out stuff without calculated SPL's and such - after seing how much C-V streeeetches the published figures.

 

Good luck with the cab project. I was into that for a little while, until I realized what I would be putting myself to. If you don't do Len's exact project (which is hard, since it uses an old driver), if you want to stick in a tweeter, you have to design your own crossover or try to find one that will work well with your cab, i.e., effectively split the frequencies and also handle the wattage you want to push through it.

But still, it would be really cool to do. I'd recommend getting something premade first, so you have something to use, and then take your time to make your cab. The last thing you want to do is rush it and end up making a junky cab. If you go for it, tell us the details!! Do a Len-type article so we can all start making one! Good luck!!!

oh yeah, check out www.partsexpress.com for a pretty nice list of drivers and speaker building materials (sound dampening stuff, grills, etc) that you can order. they also have a forum filled with VERY helpful people, I've asked a few questions there and always got great responses.

 

I've done two cabs in the past. It's not rocket science. If you have a cutoff table - spendy little item - but woooo it makes a table saw think it's a machine tool. Do all your measure and setup once. Use the flip stop - it's magic. I was amazed at not only how much faster things go - but how much better things fit.

As far as the article? I just told you the only secret you've probably never heard before (The Cutoff table). The only thing different would be dimensions and drivers - hardly worth an article.

I'm still trying to decide if 0.7Price + (+2db SPL + 2db Power Handling) > 2*Vb.

 

The 295-120 is an OK driver, except is has a 91 SPL sensitivity. It requires a bit less than 3 cubic feet for optimum performance, with an F3 of 36 Hz in QB3. You can expect a maximum of 115 SPL from this driver.

My Rockford 15" subs are 89 SPL, and I can tell you they are power hungry.

The Omega Pro 12 driver is +3 dB more sensitive, and will accept more power. It will produce about 119 SPL maximum, and it lives in a much smaller cabinet size of 1.23 cubic feet. It is more expensive, I'm sure.

 

It's also +4.5db more expensive, and not really suitable (from either F3 or Fb point of view) for a 5 string. None of the Omega's look real attractive F3 wise - Spl/Vb too high for good depth.

I think given the criteria I was using - the Dayton is looking like my best compromise. I think too that rather than stick a B102 on top of it - I'm going to try and find a closer match in terms of efficiency so it won't be useless without a biamp rig and the second cabinet. If I need 120db I'll look at more traditional big box lowspeakers.

 

AudioExpress magazine (AudioExpress.com) published some articles on building single-driver horn bass cabinets designed by Bill Fitzmaurice. You can only get the plans by ordering the back issues of the magazine. I've heard that these are small, efficient and easy to build.

DR-10: January 2001
DR-12: July 2001
DR-8: November 2001

 

TT,

I didn't know you needed it for 5-string. Yes, the Omega Pro 12 is not suitable.

The Dayton looks to be a good driver for your need. My subs are even less efficient, and good for a max SPL of only 116 at 500 watts. Two of them are enough for a typical loud bar venue. Two is not enough for outdoor OhMyGawdLoud gigs.

An Eminence Alpha 8 will match very closely to the Dayton for use with a passive crossover. It rolls off above 5,000 Hz. It would work well with the Eminence PXB2:800 passive crossover. This rolls off the Alpha 8 at an 18dB/octave rate below 800 Hz, and is high enough to keep all the bass fundamentals out.

 

It works out way more expensive again when you realise you can't hear yourself and need another cab.

So why are you looking at 12's? Sorry but it seems like you're trying to make a cat quack like a duck. If 5 string depth and low frequency response is the ultimate goal, do yourself a favour and look at a 15 inch driver at a minimum...

 

jdombrow,

Fitzmaurice's speakers truly are unique. But the low end rolls off rather high, around 80 hz or higher depending on the model, and drop like a rock. He claims that the fundamentals don't matter, but why would Acme be so popular if that were the case? His latest is a horn with a 5" speaker! -3 dB is at a modest 200 hz or so, but his application is stage vocal monitor on a mic stand, so it works for his application.

 

I wasn't "looking at 12's". I was sorting a massive spreadsheet, and that's one of about five drivers that fell out given the criteria I listed above.

I did look at the Eminence 8's as well - leaning that direction, provided the power handling match works out. I suspect with a xover that high it would be plenty. I've also considered trying to shoot for a really kicking 4 string standalone cab, and biamping with one or two subs for when I play the 5. More expense, but the result is a very modular rig with a smaller minimum hauling requirement just to make noise on a 4 string.

 

Sorry Thump. For a sec there, I'd forgotten what had happened earlier in the thread.

I like the sound of that modular rig....... did you have a specific speaker configuration in mind?