Double Bass Loudspeaker recommendations for DIY sealed DB cabinet

[JohnOH]

This is my first post but I've been lurking on TalkBass on and off for years, so thanks for all the free advice!

TL;DR: Any recommendations for a single driver for a sealed speaker cab?

Long story:

I'm planning to build myself a compact combo. Right now I use a few different pickups into a Radial PZDI (especially for piezo), then into a nice fancy mic preamp and a 1000W Crown power amp, then into an Acme Low-B 112 cabinet. I want to build all that into one package, about 60-80 litres, and if it works out I'll have a spare Acme box. So I need to buy a driver.

But I've gradually come to the realisation that I don't like ported bass cabinets. The Acme is incredible for what it does, and small and light, but to me the bottom end is just ridiculously exaggerated for double bass, and really it just sounds like a port resonating down there rather than a double bass, sort of like God blowing across the top of a giant beer bottle. It's not the Acme's fault, these days all ported speakers sound like that to me. I used to own a pair of sealed Acoustic Research hi-fi speakers in the eighties, and to me nothing has ever sounded as good since. I even played my bass through them at home sometimes, but they weren't built for gigs.

Nowadays amplifier power is cheap and light and there are some amazing light (neo) high-power drivers, so efficiency is not the concern it once was, the last time I built myself a cab 20 years ago. Problem is nearly all the drivers today are designed for ported boxes.

I've been studying Thiele-Small parameters and all that and have a reasonable handle on what it all means. My aim is get an F3 around 60-80Hz, with the proviso that the rolloff is such that 40Hz is not below -10dB. That means I will need a driver with very low Fs, and Qts higher than average, but not so high it results in too big a box, say around 0.4. Also it needs to take a lot of power to make up for the inefficiency of the sealed box. Based on that, I've only been able to find a handful of drivers that could do the job:

Faital Pro 15FH520:
A 15 that goes up to 4K and an F3 of ~ 65Hz in my box.
http://www.faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=151060150

Eminence Deltalite II 2512:
A 12-inch, also goes to 4K, and F3 about 65Hz. It's lighter and cheaper than the others, but handles less power (500W rather than 1200) and has less excursion (5mm as opposed to 8). I'm also a bit worried by what looks like some nasty break-up spikes in its frequency-curve above about 2k.
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B&C 15BG100:
Also 15 inches and lowest F3 of 58, but only reaches 1K
http://www.bcspeakers.com/products/lf-driver/15-0/15bg100

AER Studiobass:
This is really only a dream because I don't think AER are selling drivers any more. and this one retailed at about 4500 Euros! Nonetheless it had amazing specs. 12 inch, up to 2K and F3 of 60Hz in my box.
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It's been a fairly tedious process of scouring through product lists one item at a time looking at TS parameters, so I'm sure to have missed some possible candidates. Any speaker nerds out there with some suggestions?

 

[robgrow]

TS parameters only give you part of the picture and don't really tell you what a particular driver sounds like full range. Also I wouldn't rule out all ported cabinets just because you don't like the Acme (which can be tamed BTW). A ported enclosure extends the low frequency response of a given driver and enclosure by trading one large impedance peak for two smaller ones.

If you are considering a 15-inch driver, the Eminence C2515 works well in a relatively small enclosure. It has a traditional warm sound of a 15 with extended upper mids. It also has a relatively high sensitivity rating.

 

[DukeLeJeune]

I can't think of any high-power off-the-shelf neo drivers that are really well suited for sealed boxes until you get up to 18". Oh wait, the Kappalite 3015LF, but it has less top end than a lot of 18's.

In addition to the Eminence Basslite C2515 suggested by robrgow, you might look at the Beta 15A and Delta Pro 15A. I'm not vouching for their top ends, just their ability to get in the ballpark of what you're looking for down low. 15's beam more than I'd be comfortable recommending as a stand-alone solution for upright bass. Imo fairly wide dispersion is desirable for upright because it more closely mimics the behavior of your instrument, which doesn't beam.

Have you tried plugging the port(s) in the Acme?

 

[Ric Vice]

I can't think of any high-power off-the neo drivers that are really well suited for sealed boxes until you get up to 18". Oh wait, the Kappalite 3015LF, but it has less top end than a lot of 18's.

In addition to the Eminence Basslite C2515 suggested by robrgow, you might look at the Beta 15A and Delta Pro 15A. I'm not vouching for their top ends, just their ability to get in the ballpark of what you're looking for down low. 15's beam more than I'd be comfortable recommending as a stand-alone solution for upright bass. Imo fairly wide dispersion is desirable for upright because it more closely mimics the behavior of your instrument, which doesn't beam.

Have you tried plugging the port(s) in the Acme?

Duke,
That's an interesting idea, but I'm not sure the design parameters of those Low B Full Range and Flatwounds would allow for that. I'd be concerned about damaging the driver. Your TC 112 is just voiced so well for DB, that one needs look no further. I just played a large hall, last evening in a loud show band, with 4 horns and a rhythm section the Thunderchild was magnificent! Ken Jung had a Low B 112 full range for sale, so I did a comparison between my TC 112 and the Full Range. Andy builds a fine cabinet, but for Doubling I think the TC 112 is the winner. Just my opinion.

Ric

 

[DukeLeJeune]

Duke,
That's an interesting idea, but I'm not sure the design parameters of those Low B Full Range and Flatwounds would allow for that. I'd be concerned about damaging the driver. Your TC 112 is just voiced so well for DB, that one needs look no further. I just played a large hall, last evening in a loud show band, with 4 horns and a rhythm section the Thunderchild was magnificent! Ken Jung had a Low B 112 full range for sale, so I did a comparison between my TC 112 and the Full Range. Andy builds a fine cabinet, but for Doubling I think the TC 112 is the winner. Just my opinion.

Ric

Thanks for the thumbs-up on the TC112, very glad to hear it's working well for Doubling.

Andy makes great cabinets that really down the deep end. The Low-B 112 uses a woofer that's a custom version of the Kappalite 3012LF, so it has both high x-max and high x-lim, the latter being damage-limited excursion. So there is a large safety margin between x-max and x-lim with these woofers. (In Andy's 10" cabs, my understanding is that he's using a long-coil variation of the BP-102, and there's not as much of a safety margin.) So I think that, with the low-B 112, John can try it with ports plugged and as long as he backs off a bit if he hears fartout, he won't get anywhere near damaging the woofer. Of course it would be better to ask Andy than to take my word on it!

 

[JohnOH]

TS parameters only give you part of the picture and don't really tell you what a particular driver sounds like full range. Also I wouldn't rule out all ported cabinets just because you don't like the Acme (which can be tamed BTW). A ported enclosure extends the low frequency response of a given driver and enclosure by trading one large impedance peak for two smaller ones.

If you are considering a 15-inch driver, the Eminence C2515 works well in a relatively small enclosure. It has a traditional warm sound of a 15 with extended upper mids. It also has a relatively high sensitivity rating.

Thanks for your reply, robgrow. Of course, there's life beyond TS parameters, but when you live in Australia like I do, there's only a small range of gear in stores here to audition, so anything outside that you just have order it off the specs, and/or rely on recommendations.

Don't get me wrong, the Acme is a great cab, it's just that my personal taste has moved away from the sound of ported cabs. Maybe I haven't heard the right one yet, but I have heard a lot of them over the years! The DIs I use have a variable high-pass filter that I use for taming purposes, but its just something "messy" or "lumpy" about the low-end sound itself; maybe it's phase issues, I'm not sure, but when I hear I a sealed speaker it's not there. I would really like to try making one; if it doesn't work I can always go back to my current rig.

I'm not attached to using a 15, in fact would prefer a 12 but it seems to be mostly 15s that have the specs I'm after, especially low Fs.

Thanks for pointing out the C2515, I hadn't seen that before. Unfortunately, it seems to need a bigger box than I'm willing to deal with to achieve optimum damping (~180 litres). Smaller than that and it gets peaky before rolloff, which I probably should have mentioned is something I want to avoid.

 

[robgrow]

I have an OEM version of the Eminence C2515 in a less-than-optimum size enclosure. (I had both of these laying around, so I thought I'd give them a try.) WinISD did not predict good results, but to my surprise, I love the sound of this combination. This cab is strong in the 40 to 50 Hz range without over emphasizing this range, and will even reproduce 30Hz. An open E is very satisfying while not boomy. But it's the balance I really like. The DB has a lot going on in the low mids, and the C2515 reproduces this range very well. The high mids are also extended, and I don't feel the need for a tweeter. I just happen to like full-range drivers, and woofers (drivers designed to reproduce primarily LF) usually don't sound quite right to me for DB and BG. Good luck with your project.

 

[JohnOH]

... you might look at the Beta 15A and Delta Pro 15A. I'm not vouching for their top ends, just their ability to get in the ballpark of what you're looking for down low. 15's beam more than I'd be comfortable recommending as a stand-alone solution for upright bass. Imo fairly wide dispersion is desirable for upright because it more closely mimics the behavior of your instrument, which doesn't beam.

Have you tried plugging the port(s) in the Acme?

Thanks for those tips, Duke. The Delta Pro is quite close to what I'm after, not quite as close as the Faital I mentioned but a lot cheaper! I'll add that to my list. The Beta is quite different: for .7 damping it needs a sealed box of over 700 litres! I don't think the whole interior of by car is that big, let alone the trunk.

What you say about beaming is interesting and rings true. I have used a single 15 before, both in a normal ported box and in one of those strange horn boxes with the driver in an internal angled baffle behind two curtain-shaped cutouts at the front (what were they called?). I never noticed beaming but of course I wouldn't have because I was always standing right in front of it! Is this a reason to prefer a 12 for a single-driver box?

I was planning to try plugging the Acme's port, but haven't got around to it yet. I don't want to try it on a gig, so I intend to go into a practice room so I can crank it up. I'm interested to see how it affects the sound, but surely it would just be a fluke if the box just happened to be the right size to work sealed with that driver?

 

[Ric Vice]

I was planning to try plugging the Acme's port, but haven't got around to it yet. I don't want to try it on a gig, so I intend to go into a practice room so I can crank it up. I'm interested to see how it affects the sound, but surely it would just be a fluke if the box just happened to be the right size to work sealed with that driver?

+1 That's a wise course of action, before you do it, like Duke said, I'd shoot Andy an email, and get the scoop from the guy who built the cabinets. As I recall, Andy's cabinets have special cross bracing, that works in conjunction with the port.
Duke's cabinets come with port plugs so you can do exactly what he's talking about. I have a pair, but I rarely use them, because with a Walter Woods Ultra and the Ehrlund pickup I never seem to feed back. I applaud you for having the wherewithal to build your own box, I did it once with the help of my father in law we built an EV Thiel box from 13 ply baltic birch, it was a PITA. Duke builds TC 12's, 15's, and even 18's. So if you suddenly become flush with cash, you could possibly save yourself a lot of work. Not that cabinet building is a bad idea, but for me, it's a labor of love, with emphasis on the word labor.

Here's some pictures of Dukes remarkable work

Ric

 

[JohnOH]

I have an OEM version of the Eminence C2515 in a less-than-optimum size enclosure....The high mids are also extended, and I don't feel the need for a tweeter. I just happen to like full-range drivers, and woofers (drivers designed to reproduce primarily LF) usually don't sound quite right to me for DB and BG. Good luck with your project.

My experience is similar. I once built a three-way box with fancy crossovers, and couldn't stand the sound of it. I took out the crossovers and the tweeter and it sounded better. My next box was just one wide-range driver, theoretically not capable of 40 Hz, sounded better still. Before the Acme I had an Acoustic Image rig; it was nice but kind of bland and lacked dynamic range. I suppose sometimes you lose more than you gain from added complexity. This is part of the reason I'm curious about removing the port from the equation as well.

Your views are appreciated; I think I will widen my search to focus less on low extension and more on range and good damping in the given box-size.

 

[DukeLeJeune]

Thanks for those tips, Duke. The Delta Pro is quite close to what I'm after, not quite as close as the Faital I mentioned but a lot cheaper! I'll add that to my list. The Beta is quite different: for .7 damping it needs a sealed box of over 700 litres! I don't think the whole interior of by car is that big, let alone the trunk.

Using Eminence's software, I get a Qts of .90 in 85 liters with heavy stuffing for the Beta 15A.

What you say about beaming is interesting and rings true. I have used a single 15 before, both in a normal ported box and in one of those strange horn boxes with the driver in an internal angled baffle behind two curtain-shaped cutouts at the front (what were they called?). I never noticed beaming but of course I wouldn't have because I was always standing right in front of it! Is this a reason to prefer a 12 for a single-driver box?

It's all tradeoffs. Imo 12" would work better from a beaming standpoint, and you can crank in some bass boost, but you can't fix the radiation pattern with EQ.

Imo the reason the off-axis sound matters is, that's what dominates the reverberant field response, and it is the reverberant field that dominates what most people in the room will be hearing.

I was planning to try plugging the Acme's port, but haven't got around to it yet. I don't want to try it on a gig, so I intend to go into a practice room so I can crank it up. I'm interested to see how it affects the sound, but surely it would just be a fluke if the box just happened to be the right size to work sealed with that driver?

It won't be an ideal sealed alignment, but may well be "in the ballpark", as the parameters needed for a woofer to be flat to 41 Hz vented will still give you good extension sealed.

 

[Ric Vice]

............. But it's the balance I really like. The DB has a lot going on in the low mids, and the C2515 reproduces this range very well. The high mids are also extended, and I don't feel the need for a tweeter. I just happen to like full-range drivers, and woofers (drivers designed to reproduce primarily LF) usually don't sound quite right to me for DB and BG.

Well I certainly can't build what you folks are talking about, so kudos to both of you for having those mad skills. Bob, you and both owned ( actually I still have mine) Euphonic Audio VL 208's which is a remarkable cabinet, in it's own right . Dukes's 2 Way
Audio Kinesis TC-112, is a much simpler design and sounds wonderful', with DB or EB, is far more efficient, weighs 18 lbs. less. It's truly amazing crossover, flawlessly transitions from low's to high's without all the complexities of the VL 208, which
is a remarkable speaker in it's own right, but like the Acme Low B's, requires a hefty amount of amplifier power to run, which is not the case with Duke's TC-112 or the 115. I've certainly heard full range single speaker cabinets that sound wonderful, actually
the old Double Baffle Reflex cabinets in the Ampeg B-15, loaded with a JBL-130 or 140D were some of the best DB cabinet's around, when I first started gigging and they didn't have any tweeters. There are many ways to get the sound you're after.

Ric

 

[JohnOH]

Using Eminence's software, I get a Qts of .90 in 85 liters with heavy stuffing for the Beta 15A.

I should know better than second-guessing a cabinet designer! I use Linux so I can't use the Eminence software AFAIK, so I've been using the online calculator for sealed boxes at ajdesigner.com. I plugged in a Qts of .90 for the Beta 15A and although the frequency curve was surprisingly good (only slight peaking before rolloff and nice low F3) I still got a Vb of over 200 litres. The calculator doesn't allow for stuffing but it couldn't make that much difference, could it? Looks like it may not be reliable; I'd better check all my results on some different software. Any recommendations for a good online calculator? I don't think there are any speaker design programs for Linux.

My initial aim was to go for a Qts of .7 or less if possible, as clarity is a priority, but I am interested in people's advice on that too.

Thanks Duke for sharing your ideas on beaming, I am now much more inclined to choose a 12 once I can do some reliable modelling.

 

[DukeLeJeune]

I should know better than second-guessing a cabinet designer!

I am no where remotely near infallible, so second-guess away!

The calculator doesn't allow for stuffing but it couldn't make that much difference, could it? Looks like it may not be reliable; I'd better check all my results on some different software. Any recommendations for a good online calculator?

Unfortunately the only programs I know of that let you take stuffing into account are ones that you have to pay for. And it has been years since I've built a sealed box (though I do pluggable-port boxes all the time), so I really can't vouch for the accuracy of the programs I use when it comes to sealed boxes.

Eminence posts recommended designs that might be worthwhile as data points to see what a stuffed box would do relative to your models (most of their sealed designs are stuffed). Just go to the page for any of their woofers and it's a clickable PDF that's usually right next to their spec sheet PDF. Don't be scared off by the excursion-limited power handling, Eminence is covering its corporate butt by looking at full-power sine wave excursion.

My thinking is that, for upright bass, your target is probably "flat to 82 Hz", that being the first overtone of the lowest note you tune to, unless you tune below low-E. Deeper extension is fine if there are no unacceptable tradeoffs you have to make to get it, but less than 82 Hz would mean the low end of a walking bassline would fall off a bit. "Flat" doesn't have to mean zero rolloff; -3 dB is probably still okay, but just barely. Consider this to all be just armchair quarterbacking on my part... take the advice of a real bassist over mine. And this isn't taking EQ into account... you can often bring up the low end by a few dB, provided you have the excursion headroom.

 

[fdeck]

My non commercial website has an article on what I call a "small box" ported design that might be worth checking out. It uses an Eminence 2512-ii driver in a ported box, but the curve looks a lot like what you might get out of a sealed design. I've been quite happy with it, for doubling, though I play a lot less electric bass these days.

As for Linux, here are some options. First, my humble little program, which is written in JavaScript and should run in the browser on any OS:

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Of course it should be noted that this program has received relatively little expert scrutiny, and may have bugs in its analysis, so I wouldn't commit to plywood without comparing its results to some other program. I've written a version in Python as well, that will run on any platform. Second, I've successfully installed most Windows software on x86 Linux boxes using Wine. I've been amazed by how well it works.

 

[robgrow]

I can recommend fdeck's box design program. Since I have a small-box design that's far less-than optimum, I checked fdeck's box modeling program, and it comes a lot closer to what seems to be actually happening with my driver and box.

However, all T-S parameter based modeling programs can only predict the LF response of a driver and box combination. They don't really tell you what a full-range driver will sound like. I have heard some speaker cab designs that were promising on paper, but sounded less than great for DB. In the end, you have to listen.

My current favorite cab was a happy accident. I would have never designed it this way, yet it sounds great to me. This has made me view all modeling in a different light.

OK, back to practicing now...

 

[DukeLeJeune]

Fdeck's program is very useful, and Fdeck's cab design is very intelligent. Every time I learn a little more about "where the goal posts are" for amplifying upright bass, I am more impressed with the design choices he made. He nailed it as far as one-way vented design goes. JohnOH, you might consider Fdeck's design with pluggable ports.

 

[JohnOH]

I am amazed at how helpful you guys are. I've now got more options and more to think about. In particular, I realise that the fundamental below about 80Hz on a DB is only subtle and so a gentle rolloff from there down should sound natural. That allows me to consider a wider range of drivers, focusing more on what the rest of the range sounds like. Thanks to everyone.

 

[JohnOH]

Another consideration quite apart from Dukes point about beaming and 15s: is there here an issue with cone size in a sealed box? As I understand it, a sealed box relies entirely on the cone to move air. Obviously as Duke says, it's a tradeoff, but how much do people think this favours a 15 in a sealed one-way? I have room for either one.

 

[Matthijs]

I used the fdeck design as a starting point for my own 12/6 design using the deltalite 2512 II and can highly recommend it. It allowed me to build a small and lightweight cab with the low end power handling and efficiency of a ported cab and the low freq gradual drop off of a sealed cab.

The top end of the deltalite is a bit spikey, but imho not unpleasant. That probably highly depends on how the speaker combines with your bass, pickup and amp. I had more concerns with the bump over 2k and went for a flatter response and less beaming with a 6".