JohnOH

[quote name='Bill Fitzmaurice' timestamp='1416971146' post='2615666'] If sealed sounds better it's because the ported cabs you listened to were poorly done, or improperly EQ'd, or both. In blind testing of well designed speakers EQ'd to identical response and level matched even the most golden eared audiophiles can't tell one from the other, to their extreme chagrin. [/quote] I'm sure that's true, the power of suggestion is strong when it comes to sound. I sure did love the sound of my ARs though. Thanks for explaining the interactions between multiple drivers. It seems that those older-style 4x10s and 8x10s must have been a real mess in that respect.

[quote name='Bill Fitzmaurice' timestamp='1416922324' post='2615030'] First off, no fifteen will give useful response to 4kHz. On-axis you'll hear something, but off-axis the highest a fifteen will go is perhaps 1.5kHz. Even twelves aren't much good past 2kHz or so. If you want to run without a midrange driver you need to go with tens --- You do need to be concerned about the mids... You could do a vertical 2x10 in 60L net, but IMO it's easier to carry two small cabs...[/quote] That makes a lot of sense, and fits with what the people over at TalkBass said about beaming from larger cones. At some gigs I need to push the Acme, so I'm guessing I would need two tens, especially in a sealed box. But I want to build a combo, so I'm looking at putting it all in one box and driver weight is an issue. I seem to recall reading something to the effect that smaller speakers physically close together can beam like one larger speaker, is that correct? Is that why you recommend vertical stacking? Anyway, on your advice I will be looking for two tens to put in a sealed box, and I will choose the box size to get the rolloff slope I prefer. I'll look at the B102s and similar alternatives, especially anything lighter. Power handling may be an issue as my power amp is 1000W. I'll also need to learn how to model a sealed box with multiple drivers. [quote name='Bill Fitzmaurice' timestamp='1416922324' post='2615030'] Second, your preference for sealed versus ported has nothing to do with the cabs, everything to do with the instrument. Double bass just doesn't go low enough to require the lows that a ported cab produces ... Frankly I can't imagine a worse cab for double bass then an Acme, unless you don't want your double bass to sound like a double bass..[/quote] You may be right, but my preference for sealed speakers extends to listening to recorded music too. It's hard to quantify but to me, sealed sounds more coherent. When you say double bass doesn't go low, I guess you are referring to the fact that in its lower range the fundamental is much less audible than the first few overtones. None the less it is there, and to my ears it's an important part of the sound. This point has always confused me: if the fundamental is already weak, won't using a speaker which is also weak in that range exacerbate it? Surely it should be flat, then the level of fundamental will remain accurate to the instrument? I guess this is a complicated issue, because what I just said assumes that the signal source is accurate to the instrument, like say a good microphone. But in fact, unlike magnetic pickups, common bass piezo bridge pickups produce massive fundamental if correctly buffered, and maybe a speaker with highish rolloff is the antidote to this? There are so many variables. On your last point, I must admit there have been times when I don't want my double bass to sound like one! In fact, I used to tour with a theatre show that played large stadiums, and I used distortion, pitch-shifting, delays, octaves, dynamic filters etc, sometimes all at once! I don't do that any more, but I play a wide variety of music that goes outside traditional double bass music, sometimes verging on rock volumes, and some gigs that require a very big loud sound. I suppose I could keep the Acme as an extension speaker for those times and focus my combo project on getting a natural sound. Thanks for your help Bill, it is a privilege to get such generous advice from a master designer.

[quote name='SubsonicSimpleton' timestamp='1416921673' post='2615015'] ... I was suprised how high I could set the filter without thinning the sound when using a regular 4 string, so maybe if you could borrow a similar bit of kit to play with you might find that the bass extension doesn't need to go quite as far as you think, which may make the box design and driver choice a little easier. [/quote] My Radial DI has a sweepable HPF on it that I use just like that to tame the ACME. It doesn't have frequency markings so I just do it by ear. I usually roll off some, and for smoother jazz gigs I roll of quite a bit. You're on to something there, I'll try to figure out a way to measure what I'm always rolling off and design around that.

This is my first post here. Please let me know if this would fit better in the double bass forum. I have already asked this question on talkbass.com and have received some great information and advice: http://www.talkbass.com/threads/loudspeaker-recommendations-for-diy-sealed-db-cabinet.1116442 but I'm interested to see if the good folk here have any further ideas. TL;DR: Any recommendations for a single driver for a sealed speaker cab for double bass? 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. Either a twelve or a fifteen would fit in my box, so whatever works best on its own. 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 between 0.3 and 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. [url="http://www.faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=151060150"]http://www.faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=151060150[/url] Eminence Deltalite II 2512: A 12-inch, also goes to 4K, and F3 about 65Hz. It's lighter and cheaper than the Faital, 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. [url="http://www.eminence.com/pdf/DeltaliteII_2512.pdf"]http://www.eminence.com/pdf/DeltaliteII_2512.pdf[/url] Some helpful souls over on TalkBass also suggested the Eminence Basslite C2515, Beta 15A and Delta Pro 15A. I've also just started looking at Beyma, who have some drivers that could go in a sealed box and get up to 5 and even 6K. It's been a fairly tedious process of scouring through product lists one item at a time looking at TS parameters and specs, so I'm sure to have missed some possible candidates. Any (sealed) speaker nerds out there with some suggestions or advice?