Piccolo8, cab build for piccolo bass

Time for a new cab build
After the 210 with coaxial mid/high driver it's time for something totally different(and less complex).
It's going to be a cab for my piccolo-bass, it should also be good enough as rehearsal/small-gig amp for regular 4-string basses.
Concept should be simple, 1 driver, small, cheap and enough power for rehearsals and small jazz/blues/pop gigs.
Since it's also a cab for piccolo bass it should not have a tweeter, cranking the mids could blow it up.....
Because it's a tweeterless concept I need a driver that's not to big(better dispersion) and still can handle some power --> 8" driver.

Options:
-Faital pro 8 pr 200
-Beyma 8G40
-Beyma LW30
-Ciare 8.50ndw
-Ciare NDC8-3
-Oberton 8MB201

The faital is to expensive and it's already used in the Crazy8 &88 (don't wanna be a copy-cat )
The Ciare's are also to expensive.
The Beyma 8G40 is a great driver but it's also more expensive then the Oberton which has almost the same technical specs.
For those who want to build the Piccolo8 and can't buy the Oberton then the Beyma 8G40 is the perfect replacement driver (it has slightly more top end but the Oberton probably has better dispersion so they won't sound very different)

Conclusion, it's going to be the Oberton 8MB201 which costs a fraction of the Faital but will perform almost the same (the Faital can be tuned lower though but that's not necessary for 4-string).

The cabinet will be horn-reflex, that's a ported cabinet but the port's mouth will be approx. 1.5 times the cone area. When optimally tuned it will perform slightly better then a regular ported cab.

Here are some pics of the driver, I just picked it up at the importer.

I couldn't resist to connect the 8" driver to the amp just to hear how it sounds without any cabinet.
Very nice mids, enough sparkle for slap 'n pop but never sharp sounding.
Xmax looks what the manufacturer states, 5.75mm. Even without a cabinet hefty excursions don't bother this driver much.
Of course you can overpower it but for an 8" driver it's very good.

Very promising, hope to show the design of the cabinet soon.
What I can tell is that the baffle is tilted backwards so you can just place the cab on the ground(for maximum coupling) and still receive enough mids 'n highs.

Here is a drawing(profile) of the cabinet.
Hope to build this little cab soon

Here's the difference between horn-reflex and a normal ported cab. The slightly higher output in the mid/bass compensates for the baffle-step. Both simulations show the 8MB201 in 11liters (the horn-reflex cab is bigger though cuz of the horn).
The peaks and valleys of the horn-reflex don't look nice but in reality they aren't that pronounced. The simulation isn't fullspace, it's halfspace(floor).

Here's the simulated max spl at 200 and 400watts.
Up to 200watts the driver is(from 60hz and up) not mechanically limit in this cab

DD_BigBottom said:

I wouldn't stress too much over this.
A piccolo bass is in the same frequency range as a regular guitar.
Any bass guitar cab design with a reasonable mid-range response will work fine with the piccolo.

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True,
I still think a single driver solution will work great, keeps the sound clear and the attack focussed.
The cab should also function as a micro-cab solution for regular 4-string.

DD_BigBottom said:

BTW - what software are you using for the speaker response plots?

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AJhorn

DD_BigBottom said:

Any bass guitar cab design with a reasonable mid-range response will work fine with the piccolo

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Depends on what you're after. If you EQ it to get e.g. Stanley Clarke's solo tone (extremely cranked mids) you will blow the tweeter in most of these bass cabs when you go loud.
That''s also one of the reason I want a single driver solution.

will33 said:

I can see the large port area contributing a bit more output....does this qualify as an old school "slot port" or slot loaded driver? I always have a helluva time figuring tuning on those. I've also been told they can "drift" under varying power levels, so a small signal impedance measurement or "dancing rice" method doesn't tell the whole story.

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It's like a slot ported or tube ported cabinet except that the port starts with approx 1/4th of the cone area and ends at approx 1.5 times the cone area. This should yield a slightly better coupling to the air. Tuning these kind of cabs can only be done by simulating them in e.g. AJhorn.
Don't recall that the tuning of these kind of cabs will drift under varying power levels. Those horn-reflex loaded designs are especially suited for PA use.

will33 said:

I don't have gear to test beyond small signal sine and rice on the cone. Can AJhorn simulate that sort of thing?

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The version I have can't do that, and as far as I know no simulating software can do this, maybe Akabak.

The only way to find out is to do impedance sweeps on the whole cab at different input levels, 1, 10, 100watts, etc.

DD_BigBottom said:

I'm looking for a small box solution for bass guitar in small club type venues and look forward to see how your project turns out.

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Cool.
If you want to build it, the Beyma 8G40 will work in that cabinet too and perform approx. the same
If you really want to use the 8MB210 then there's allways a way to get/ship it to you.

Yeah, plywood panels are ready.
Lets build this cute cab!

DukeLeJeune said:

Very interesting design!

I tried something similar years ago, but without the benefit of a modelling program, and the bottom end was disappointing. The "mouth" of my horn was about 1/2 the cone area as I recall, and that may have been the problem. I wasn't taking into account that it's not only a horn but also a port.

I presume you've worked with AJHorn before and found its modelling to do a good job of preducting measured response down low, say south of 100 Hz?

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Thnx for chimin' in Duke, the port area, throat area and lenght are all important. Actually it's still a ported design but when executed well it should have better coupling to the surrounding air, this is where the greater mouth area comes in.

AJhorn does a great job, it is also used extensively by a German DIY loudspeaker magazine that has showed several times how well the simulations agree with the measurements.

I only would like to have the latest version of that program cuz it's more flexible then mine.

Almost done

Munjibunga said:

Are you going to put some kind of cone protection on it? I notice there's no recess around the front.

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There's going to be some sort of grill, but that's for later concern.