Even more so than a typical project, this one is nearly all about the compromises. There is no perfect solution given the constraints involved. The first post also says: "Loud over deep bass".
It's also about relativity. How much bass will this have vs. the amount of bass everyone else has? Or the amount you had previously? Is a lot of midbass good enough?
Unless I missed it, you never did respond with your data about the DVC 10" version you used previously (box size, etc.). That 10" looks like about 88 dB with both coils in parallel. And an f3 of about 50 Hz in 1.2 cubic feet sealed. I'll assume that's what you had.
The 290-382/Goldwood is about 97 dB sensitivity, but f3 of around 70 Hz in 2 cubic feet sealed (56 liters). Looks like the new box would still have 2 dB more output at 50 Hz than the old 10" DVC one at the same power and driver count (in practice this would mean going to 100 watts mono and paralleling the new drivers to get down to 4 ohms). At 100 Hz, the new box would have 7 dB more output for the same input. The Goldwood can't take much power down low due to its 2 mm Xmax, but you may not have much power anyway. Below around 70 Hz, 20-30 watts looks like a reasonable limit. Above 100 Hz, 100 watts looks OK. If you were not using the full 50 watts of your old amp, this setup still could make sense.
The 292-806/GRS is about 94 dB sensitive, and would have an f3 of around 48 Hz in 2 cubic feet ported when tuned to 45 Hz. It can handle significantly more power, since it has over 3x the Xmax of the Goldwood. But at 20 watts of input and at 50 Hz it only has a 3 dB advantage over the Goldwood sealed (5 dB over the old 10" DVC). At 100 Hz and with the same power in both drivers it would also have about 5 dB advantage over the old 10". With more power, the GRS can get louder without exceeding its Xmax. If you can take the power up to 100 watts/driver, you should be around 8 dB over what you had with the 10" (roughly 5 dB in sensitivity difference and 3 dB for doubling the power). If your amp can do 200 watts mono at 4 ohms, this seems like a pretty good approach.
How much power you want to put into the drivers should heavily influence your selection.
Last edited:
The box size makes for a lot of the weight.
Here is a pair of GRS 12PT-8 in a 160L box compared to the B&C10CL51 in a 57L box, both with 60Hz Fb and 14volt input:
The big box, GRS 12PT-8 2x12" (dark trace) is maxed out for excursion at just 14V.
The B&C 2x10" can use 37V within Xmax, and put out more output, as can be seen in post #34.
Ride on!
Art
I'm confused. On the right your image says "Goldwood GRS", and the comment mentions Xmax of 2 mm. The GRS is a different driver than the Goldwood. GRS also has a 6.8 mm Xmax. The Goldwood's is 2 mm.
Last edited:
Two speakers will give you an extra 6dB output and require double the power. To double the perceived volume of a sound requires a 10dB increase, so you are not gaining a huge amount. Efficiency is the key here, and not trying to go too deep on the bass - I believe you are expecting the impossible, since there is no magic solution to reproducing loud deep bass with such power/weight/size limitations. As weltersys so correctly states - Hoffmans' Iron Law. Your best chance of covering a large number of riders is by using multiple systems, so persuade ten of your mates to build one too!
I haven’t read all of the replies but my suggestion would be to make the enclosure out of fiberglass. You can sandwich it for stiffness and really put it where you want. You can drape it over the wheels, you can put batteries and amps down low for a good low center of gravity. It would be a ton of fun!
I wish you lived in AZ, I would help out!
I wish you lived in AZ, I would help out!
My mistake- the sim was for the 2x12" (dual) GRS 12PT-8, which does list a 6.8 mm Xmax. The output with 2mm excursion is correct for 15 (not 14, another mistake) volts, about 56 watts into 4 ohms.
To hit 6.8mm excursion would require 51volts, about 650 watts into 4 ohms, requiring a different class of amplifier and batteries than the OP has been considering.
Art
Previously someone suggested car amps. Have you looked at any of those? If you want to do a higher power setup, they might make the most sense.
Williston Audio Labs on youtube has a lot of amp tests up. There are quite a few small class D amps with moderate power. He gives power output, current draw, and efficiency into various impedances. Some of them are cheap enough that they're competitive with simple amp modules, and they'll get rid of the need to run higher battery voltages or some kind of step up. Car amps often have more onboard crossover/filter options than simpler modules as well.
Here's a search of his videos for "cheap"
https://www.youtube.com/c/bigdwiz/search?query=cheap
And a couple cheap mono amp reviews
I'd start by trying a woofer I already have, a house-brand version of the Eminence Delta Pro 15", towed behind my bike on a trailer since the 3/4" plywood cabinet wouldn't fit on my rear rack. It's very sensitive, probably overkill on power handling though. Then see what cheaper smaller woofers can keep up with it at lower cost. And preferably with a neo magnet for lower weight (Eminence's Kappalite is about ten pounds lighter than the Delta Pro.) Try making a cabinet from curved 1/4" baltic birch to keep the weight down.
And keep an open mind; a bunch of small speakers with neo magnets might add up to one big woofer.
And keep an open mind; a bunch of small speakers with neo magnets might add up to one big woofer.
I dont have expertise to suggest a good subwoofer for your bike yet but for sure the Amp you will need to drive your sub is. BikeTronic check the Hypex nCore based amps for 12V http://biketronics.com the basss quality of Hypex is top class no one can come near it.
Forget using wood for the enclosure. It will end up being far too heavy, given that the sides must be flat and thick to be stiff enough.
Use two neo woofers installed in opposite ends of a Sonotube tube. (Cardboard tubing used for pouring concrete columns) This will be vastly lighter than anything made of wood, because the cardboard is loaded in tension, not bending. Mono the signal before the amplifier and drive both woofers in parallel to get the impedance lower, to get the most output from the low voltage amplifier.
Use two neo woofers installed in opposite ends of a Sonotube tube. (Cardboard tubing used for pouring concrete columns) This will be vastly lighter than anything made of wood, because the cardboard is loaded in tension, not bending. Mono the signal before the amplifier and drive both woofers in parallel to get the impedance lower, to get the most output from the low voltage amplifier.
Here's a bike system that uses sonotube enclosures for bass:
http://www.cathodecorner.com/loudbike/
A small negative is there a bit of "wasted space" around the cylinder so to achieve the same volume as a plywood box you'll end up with a tube that may be longer/wider than you'd want.
http://www.cathodecorner.com/loudbike/
A small negative is there a bit of "wasted space" around the cylinder so to achieve the same volume as a plywood box you'll end up with a tube that may be longer/wider than you'd want.