NiToNi

Thanks, peniku8. I am in no hurry and I guess it all probably looks more complex than it is, in its assembled state like below, but laid out piece by piece it's all just cut from sheet plywood. Will send you a PM asap.

Could you recommend someone in Europe who could CNC all the pieces of my own subwoofer design (Solidworks) without it costing an arm and a leg? It's a one-off custom project for my own HT.It’s a pretty serious piece requiring a few advanced cuts, going by what a few friends ‘in-the-know’ have told me, so I don’t know what kind of machine is required - although in my world, it’s basically just a “simple box” with no rocket science involved. But OK, the bracing is pretty brutal, so if Apollo 13 had been as structurally sound they would probably never have had their “Houston, we have a problem” moment… 😉Here’s a link to the design (HTML eDrawings). Use right-click for options like removing or isolating pieces: Subwoofer_assSplit_200617.htmlI’m open to suggestions from anywhere in EU or the UK as long as the cost is competitive to justify the shipping cost.

Has anyone measured the complex inductance parameters (Re, Leb, Le, Rss, Ke) of the 8 ohm version of the 21DS115? I find that simulating in Hornresp using these changes the response quite a lot.

I noticed there is a "low distortion" version available of this driver, called the 214.50LD: http://www.lavocespeakers.com/lavoce/assets/datasheets/1491384956_LAVOCE_SAN214.50LD_21in_SUBWOOFER_A.a.pdf

Aha... 😋

€383 for the 21DS115-4 is a very good price. Would you mind sharing a link? Toute Le Haut Parleur charges €450 for the 4 ohm version so I guess you're looking somewhere else: https://en.toutlehautparleur.com/speaker-b-c-speakers-21ds115-4-ohm-21-inch.html I agree with you that at least on paper it is pretty much a wash between the 21DS115-8 and the SAN214.50 for your particular application (Othorn). The LaVoc is cheaper but if you like to change your stuff out ever so often, the B&C drivers may hold their value better in the second-hand market.

No worries and good luck with your project. Although just so you know all your options (or to make your life harder depending on how you see it), let me point out that there’s also a 21DS115-8 available (8 ohm nominal and Re 5.1 ohm)...

Yeah one-third of that should be more than enough if you have enough power and can make a slot port. TBH I don't think you need to worry about the difference between 2.2 ohm and 2.4 ohh but sure, the LaVoce SAN 214.50 is a worthy alternative if you want to be (overly) cautious. Power handling is the same, Xmax just a bit more, Xmech quite a bit less. As you know, less motor force can be an advantage in a vented enclosure but a disadvantage in a tapped horn. In the real world though, I doubt there will be enough of a difference for buyer's remorse, especially if 10% cheaper. If you do go down the route of the LaVoce, it'd be great to hear your impressions in due course.

Re of the driver is 2.2 ohm so a System DCR of the same is only natural. I think you have to expect that this could be the case. OTOH if your amp is fine driving 3 x 8 ohm nominal, those woofers are also likely to have an Re lower than 8 ohm. Use their Re in Ohm’s law instead to check the resulting impedance your amp is fine with driving today. Or even better, sim them to see System DCR and impedance curve (which woofers and in what sort of enclosure do you use?) If less than 2.2 ohm, you’re most likely good to go. Otherwise there’s always the FP14000 clones: https://smiths.en.alibaba.com/product/60686863904-805150637/lab_gruppen_2CH_fp14000_bass_amplifier.html

Seems like that could be a bit on optimistic side... ...at least in simulated theory Seems like you will be able take the 21DS115-4 up to about 61V in that 4.5 gross cu ft enclosure while staying within reasonable excursion... True of course but it's only after response shaping of the cabinet & driver system's passband that it becomes truly useful, especially a strong pro driver in a sealed cabinet. This is the same as above after LTW F0=58Hz, Q0=0.35, Fp=20Hz, Qp=0.707: Max SPL 112dB, F3=20Hz, F6=15Hz and F10=12Hz. The borderline excursion at around 10Hz should be mitigated by electronic roll-off elsewhere in the signal chain: Again, only theoretical anechoic response in the simulated world of course. In-room response will of course require further ("different") EQ to flatten the response. Nevertheless, if you stick to only reducing gain (without any boosting) during the EQ process, the SPL capability at the low end of the passband (e.g. ~20Hz), in-room net after adding room gain and deducting compression, will ultimately dictate the performance throughout the whole passband (e.g. ~20-100Hz). Also subscribed and looking forward to your test results, Ricci! A couple of these drivers are potential candidates for my own system - unless the bigger brother 6" VC is expected to follow soon... EDIT: Simulation file (WBCD5 Excel XLS file) attached for anyone interested in playing around. Woofer Box and Circuit Designer 5.zip

Ricci referred to sensitivity above as 103.67dB/2.83V/m. However as you can see from the graph below, you will only get that sort of sensitivity above a bit over 500 Hz. From 130Hz and below, sensitivity will be in the double digits only. Flatting the curve with EQ, targeting an F3 of 20Hz and a Q=0.707 rolloff, the "useful" sensitivity is more like 88.45dB/2,83V/m. That's in free air. Any smaller sealed box than that will gradually reduce sensitivity down low where it counts. 2.83V is 3.65W in the case of this driver (TSP as per DB) and is the better way of referring to a driver's sensitivity IMHO but if you insist on 1W/m (1.48V), sensitivity is 98.12dB and the graph looks like this:

Gotcha

Ah... that explains it! Sorry, I missed that part completely. There's no mentioning of a 4 ohm version on B&C's website so I hastily concluded there's only one model available... So what sort of peak voltage (burst) could you safely put through the nominal 4 ohm VC from a thermal perspective you reckon and what sort of compression could one expect at that level?

This new generation of B&C subwoofers look very interesting. I like the stronger motors compared to the previous generation for brute-force operation in small sealed boxes. e.g: This is with a LTW of F0=79Hz, Q0=0.45, Fp=20Hz, Qp=0.85. The gray line is max SPL at Xvar of 16.5mm. Four of those on 3400W each should do 122dB at 1m To go louder down deep, a vented 135L enclosure tuned to 15Hz (Dv=8", Lv=120" which may be a deal killer of course) seem to be able to do this with a bit of flattening EQ (HP LR4=15Hz; PEQ Fc=15Hz, 5.5dB, Q=1; LTW F0=50Hz, Q0=0.286, Fp=13Hz, Qp=0.44... LTW because Jeff Bagby's WBCD5 doesn't have a built-in shelf filter): Only two of those on 3400W each would be enough for 122dB at 1m How come though that your measured Re of 2.2 ohms is so far off factory spec of 5.1 ohms? That's less than half and would rule out some amplifiers not happy driving less than 4 ohm loads (e.g. bridged Class D). I mean this is nominally an 8 ohm driver with a rated minimum impedance of 6.5 ohm. On the same note, nominal power handling of 1700W is based on rated minimum impedance. Ohms law yields 105V @ 16A. Based on your own measurements, what peak voltage (Vp) would push your driver to Xvar of 16.5mm at 15Hz? Around 75V?