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8" Speaker Recommendations

#41
MountainMikeCS said:
27094685[/URL], member: 362716"]
Click to expand...
Actually I'm looking for a less-than $100 driver and then to pick that up used for under $50. Then if it sounds well I'd build a new cab same size with better materials - something light but with a solid surface - and pay attention to the details. I'm obviously not a skilled woodworking guy - other than installing molding and building a chicken coup!
 
#42
I ran the numbers on a driver I have that's optimized for bass guitar in a small enclosure and the best I can do (with the port width decreased to 6") is:

Vb = 0.5 cubic foot
F3: 88Hz
F6: 75Hz
F10: 62Hz
Sensitivity: 96dB/1W/1M
Mechanical power handling: 150 watts above 60Hz, really needs a 4th order HPF set at about 50Hz

If the enclosure increases to say 0.75 cubic foot then things improve (using the original port dimensions) to:
Vb = 0.75 cubic foot
F3: 75Hz
F6: 65Hz
F10: 55Hz
Sensitivity: 96dB/1W/1M
Mechanical power handling: 150 watts above 55Hz, needs a 4th order HPF set at about 45-50Hz
*** This is a custom designed driver, very much optimized for this type of application.

Dropping a middle of the road stock driver (Beta 8A) into the box:
Vb = 0.5 cubic foot
F3: 81Hz
F6: 71Hz
F10: 62Hz
Sensitivity: 96dB/1W/1M
Mechanical power handling: 50 watts above 60Hz, really needs a 4th order HPF set at about 50Hz

The tradeoff becomes pretty obvious, in order to have acceptable sensitivity the LF power handling gets reduced to 50 watts for less than 60Hz, that's a huge sensitivity (or maximum SPL) tradeoff, though this driver does pretty well for <50 watt applications. This driver also performs well in small boxes, and was the basis for the custom driver modeled earlier except without the mechanical power handling limitations. The custom driver (Neo) is almost 2x the cost of the Beta 8A.

In a .75 cubic foot box with a 2" shorter port, the performance improves BUT the mechanical power handling falls to about 35-40 watts whereas the custom driver maintains 150 watts mechanical power handling.

This is how that design process works, the balancing of compromises and tradeoffs to get the maximum performance for the application.
 
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#43
MountainMikeCS said:
Actually I'm looking for a less-than $100 driver and then to pick that up used for under $50. Then if it sounds well I'd build a new cab same size with better materials -
Click to expand...
If you're willing to rebuild this cab, I'd recommend just building a different cab, one built to an actual design -- not something vaguely resembling something you saw on the YouTube.

@agedhorse's analysis (quite generous and valuable, especially given the dis' you put on him at the start of this :D) points toward the difficulty of what you're trying to do, which seems to be finding a driver on the cheap to salvage this particular box. The "middle-of-the-road" 8-inch driver he cites -- the Beta 8A -- is 90 clams at Parts Express, and I don't think you'll find one used. And it's the same with other high-performance 8's -- it's something of a specialized niche and the used market is small. Do you really want to invest 90 Simoleans in this untested 'design'? Also, don't forget you'll need a real HPF if you don't want to keep buying new drivers for it, especially considering you plan to drive it with your Tonehammer 350.

If your goal is to make a small cab to use for bass, start over. And maybe use a ten, like Guns and Guitars Guy did. (They're much more common and cheaper.) Only actually copy a proven design, not a "scaled" version that resembles one that's itself unproven. And if the goal is just to do something with this enclosure, pick something else. Do you have a cat? :D
 
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#46
agedhorse said:
I ran the numbers on a driver I have that's optimized for bass guitar in a small enclosure and the best I can do (with the port width decreased to 6") is:

Vb = 0.5 cubic foot
F3: 88Hz
F6: 75Hz
F10: 62Hz
Sensitivity: 96dB/1W/1M
Mechanical power handling: 150 watts above 60Hz, really needs a 4th order HPF set at about 50Hz

If the enclosure increases to say 0.75 cubic foot then things improve (using the original port dimensions) to:
Vb = 0.75 cubic foot
F3: 75Hz
F6: 65Hz
F10: 55Hz
Sensitivity: 96dB/1W/1M
Mechanical power handling: 150 watts above 55Hz, needs a 4th order HPF set at about 45-50Hz
*** This is a custom designed driver, very much optimized for this type of application.

Dropping a middle of the road stock driver (Beta 8A) into the box:
Vb = 0.5 cubic foot
F3: 81Hz
F6: 71Hz
F10: 62Hz
Sensitivity: 96dB/1W/1M
Mechanical power handling: 50 watts above 60Hz, really needs a 4th order HPF set at about 50Hz

The tradeoff becomes pretty obvious, in order to have acceptable sensitivity the LF power handling gets reduced to 50 watts for less than 60Hz, that's a huge sensitivity (or maximum SPL) tradeoff, though this driver does pretty well for <50 watt applications. This driver also performs well in small boxes, and was the basis for the custom driver modeled earlier except without the mechanical power handling limitations. The custom driver (Neo) is almost 2x the cost of the Beta 8A.

In a .75 cubic foot box with a 2" shorter port, the performance improves BUT the mechanical power handling falls to about 35-40 watts whereas the custom driver maintains 150 watts mechanical power handling.

This is how that design process works, the balancing of compromises and tradeoffs to get the maximum performance for the application.
Click to expand...

@agedhorse thank you so much for all your work on this. This really drives home the point you've made in earlier posts: "Design your cab for your driver."

This prototype design was very easy to build and very quick to build - probably because of the simple reinforcement of the rectangular vent structure which was then used to mount the two side walls adding quick stability. The real cabinet I built was a more difficult, longer build, not just because it uses two circular vents but because I didn't have the right tools for the job. I am lacking a good table saw and a band saw; I've been making due with normal tools for home renovations - a length-extending compound saw and a hand-held rotary saw for board cuts and a simple hand-held jigsaw for circular hole cuts. The jigsaw is low quality and kept jamming. I also experimented with a hand-held router and a center/mounted jig to cut the speaker and vent holes on the newer cab but it was nowhere near clean working with plywood.

I included a few pics of the final cabinet below. One pic without the speaker screen and another with the screen layer on top but not yet mounted on the speaker. The speaker mounted is currently a Hartke 10" 100 watt 8ohm speaker from the Hartke 4.5xl 410 cab I owned. The speaker below the cab is the speaker I designed the cab for - a 175 watt 8ohm 10" SWR speaker taken from an SWR Goliath JR 210 cab. The SWR speaker sounds amazing i this cab - clear lows and mids and very loud. I don't have any tools for testing how well it is performing but the SWR speaker outperforms the Hartke in volume and low-tone quality.

I used 1/2 plywood for the walls and baffle and two semi-circle 1/2 board pieces as backings for the t-nuts i used for speaker mounting glued behind the baffle as the plywood wasn't strong enough to mount the speaker directly to.

You can see the lousy job I did of cutting the vent circles.

Also - for the depth of the vents I used PVC pipe of the same diameter in the vent size recommendations, glued in place but in need of a paint touchup over the excess glue.

I applied two coats of spray-on primer and then two coats of truck-bed sealant - all of which was absorbed into the plywood instead of coating and hiding the plywood grain. Lesson learned here - either use grain sealer or some primer that will completely seal the grain or don't use plywood if you don't want to cover the structure in tolex. I used two layers of Poly-fil fiber-fill to insulate the box, which helped warm the sound

I have purchased a few recessed handles and a back-plate for mounting the 1/4 jack which I have yet to install.

Lessons learned here:

1. Pick your driver first and build your cab around it. Eminence has great suggested cab design specs on their website with each speaker.
2. Invest the time, before designing, to learn how bass cabinet design works, what all the specs mean, and how to apply them. This is critical.
3. Invest the time first, before designing, in research into materials, designs, build methods before jumping into a build. There are many resources online for this and many videos by cabinet builders to learn from.
4. Secure the correct tools before you build. This could be preventative. In my case I believe I could make use of a more expensive jigsaw and a better rotary saw in other home projects, so money well spent when I buy them.
5. Ask for help with what you still don't know.

Because I had the wood and speakers already this project - which basically started as an experiment to see if I could replicate a decent build like I've seen done online, only cost me about 100 in supplies- mostly glue, paint, primer, insulation, wire, jacks and better wire strippers than I already had. But I learned that once you have the tools you can easily build a small, lightweight ( yet aesthetically simple ) cab for one or two 10" speakers for under $100 - but good Eminence speakers will run up to an additional $150 each - unless you find them on sale.

The advantage over buying a new cab: Having a cab built to the weight and size you need, at a slight possible cost savings, depending on the speakers you choose.

Still to figure out: What material to use on the next build? I'm not happy with plywood unless I can pick up an affordable covering to cover the plywood. I need to research where to get tolex for cheap. MDF is too heavy. Reinforced HDF might be worth considering, with a solid-wood baffle to increase strength.

pic1-no-screen.jpg
pic2-screen.jpg
 
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#48
Ports are WAY too large for that driver. One of those ports will be a lot closer. Where did you get the porting information from?
 
#50
MountainMikeCS said:
I also experimented with a hand-held router and a center/mounted jig to cut the speaker and vent holes on the newer cab but it was nowhere near clean working with plywood.
Click to expand...
IME, a router with a circle guide IS the best way to cut a smooth, round circle in plywood. I'm wondering if maybe you tried to cut the full depth of cut in one pass? You need to limit each cut to no more than about a quarter-inch depth, so it takes three passes to cut through 18mm plywood. Plywood IS the right material, BTW. (In that regard, you've already made a big improvement over the Guitars and Guns Guy. :D) A good plywood face can be filled and finished to not show the wood grain -- you don't HAVE to use Tolex. Acrytech's Duratex is a popular water-based coating (paint) that a lot of DIY builders here use.
 
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#51
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