A little nudge? Cab design question

[basscooker]

Ok disclaimer;
Yes they are bass drivers.
Yes I have TS params.
Yes I'm using software.
No, I can't give out any more details about the driver besides being an Eminence. Not an off the shelf driver.

Question;
I've been banging out some models and simply can't find a good compromise.

Q is 0.7 but sealed models are kinda ugly under 3 cubic feet for a single 10.

Ported models show a big 3.5 to 5 dB peak in the high 90s to mid 100s. No reasonable port dims or cab volume smooths it out.

When I get a promising frequency plot, the excursion is ridiculous, and/or port velocity is really high; taming either destroys the freq. plot.

So cab design 1001..... Suggestions of things to try?

10"
Fs 66
Xmax 3.7mm
Vas 1.2

I'm not asking you to design it for me. Half the fun is the journey... But maybe a little nudge or a hint would be awesome.

Trade-offs, compromise, sacrifices etc are expected with every design. I just can't find the middle ground here without at least one (predicted) pretty major design flaw or limitation.

Thank you

 

[Al Kraft]

I'm not a speaker/cab designer, but I have heard Duke and Andy talk about getting to a place where they introduce a little art and Kentucky windage to the science (and math). I suspect (but could easily be wrong) that math will only get you into the right ballpark and some testing/experimenting might be needed for the fine tuning.

Hopefully someone actually qualified on the topic can be more helpful. That's all I got.

 

[basscooker]

I prefer being more confident in what the graphs tell me before I make sawdust. I HAVE been pleasantly surprised in the past by a prototype giving real-world performance that exceeds what I imagined from looking at the graphs.

Unfortunately I'm limited to enough wood on hand for 1 cab at most. I got up today hoping to have a proto at least designed if not even the panels cut. Looks like a "no" so far.

 

[CajunBassPlayer]

You may want to look at the Bill Fitzmaurice designs. He has multiple designs and all the sound plots for each. I have built 4 of his cabs.... a 210 and 212 for guitar and a 112 and 212 for bass. I am using the 112 in my studio and love the lows and how transparent it sounds. Only my Am P Bass thru it and it rumbles the low end but does not loose the mids and highs. Best of luck..

 

[basscooker]

BFM designs require a specific driver or drivers. These are not them. Thanks tho. I can design cabs. I have just never hit a wall like I am with this driver. I found a great frequency response plot with a few different ideas.... But I don't want a cab that farts out at 40 watts or chuffs from the port.

 

[basscooker]

Argh!

I'm reeeealy considering just making guitar cabs with these. Can't screw THAT up. Geez. Nothing I've tried today has given me any "on paper" love.

If I move forward and go with anything I've modeled today a (sealed) 2x10 will be 6 cubic feet, and +/- 3dB from 78-3.5k and +/- 6dB from 63-5k. Excursion limited to 175 watts. Why bother, really.

 

[Al Kraft]

Have you considering flaring or radiusing the port ends if you are out of trade space with regard to changing port diameter/geometry and concomitantly adjusting port length? It won't fix every problem, but strictly from an aerodynamics standpoint smoothing at the inlet and exit may help when the port speed would otherwise be too high.

Different port shapes with inlet and outlet smoothing might also provide a potential improvement. DISCLAIMER: I am clearly out of my depth on this topic, but in the world of aerodynamics similar tricks that are comparatively small changes to the overall design can often make noticeable improvements.

 

[pie_man_25]

Argh!

I'm reeeealy considering just making guitar cabs with these. Can't screw THAT up. Geez. Nothing I've tried today has given me any "on paper" love.

If I move forward and go with anything I've modeled today a (sealed) 2x10 will be 6 cubic feet, and +/- 3dB from 78-3.5k and +/- 6dB from 63-5k. Excursion limited to 175 watts. Why bother, really.

Sounds like you're just having a day. Everybody has a day. Where nothing works and you just can't catch a win. Sounds like you should just bang your head at it for a couple hours, and then walk away and find a break with a nice cold beer, or a good walk in the rain or something else that can keep your body occupied so your brain can just simmer on it.

Whatever the solution is, I'm rooting for you, we're right here with you, and nobody's unique in having a day.

Edit: probably not a permanent solution, but what about an isobaric?

Also, is this a driver made to your specs, or was it one that you bought a load of cheaply or something? I'm sorry I'm honestly just asking that one to ask it.

 

[Al Kraft]

I know this is a potential solution you don't want to hear, but have you considered a passive radiator? Maybe the Eminence folks could send you something to match up with the the driver(s).

If you're close on the ports though, I would still play with the geometry trades and flaring first.

 

[Downunderwonder]

When in doubt, make the box bigger.

 

[BioWeapon]

You can probably make use of that 3-5dB 90Hz hump if you're willing to explore adding some horn-like features. Take that bump and turn it into a rising response into the midrange, a la BFM Jack maybe? I don't know if that's something that's up your alley but I didn't see you state design goals anywhere, like small size, low bass, super loud, etc.

Also, have you considered an isobaric design? It would allow you to cut down the Fs spec and get deeper bass, but it won't make you any louder and certainly won't help with weight.

 

[HaphAsSard]

Ported models show a big 3.5 to 5 dB peak in the high 90s to mid 100s. No reasonable port dims or cab volume smooths it out.

When I get a promising frequency plot, the excursion is ridiculous, and/or port velocity is really high; taming either destroys the freq. plot.

A very high QTS maybe? An Alpha 10A variant?

You could try tuning it below 40Hz until port velocity is of less consequence, and line the bujeesus out of it to tame the peak.
Simulate it in WinISD: "Box" tab, "Advanced->" button, change the Qa value from 100

to 50 for a lined, 10 for stuffed, 5 for stuffed and compressed, 1 for heavily compressed. At 1 the upper impedance peak can completely disappear.

Or try aperiodic/leaky. Of which I know next to nothing.

 

[pie_man_25]

Or try aperiodic/leaky. Of which I know next to nothing.

Aperiodic could really work as well, potentially. I think they tend to be used in lower volume contexts, but it can help to reduce box sizes. I couldn't tell you much about modeling them, though. Under ideal circumstances I'd say to pick two designs that look okay and one that looks like crap, build those, and then figure out what you could do to make one of them meet your goals.

These aren't ideal circumstances though.

 

[gmarcus]

A high q driver will work well in a transmission line

 

[smart51]

Transmission lines don't have port chuff. A tapered line doesn't have to be huge either.

 

[lug]

I know this is a potential solution you don't want to hear, but have you considered a passive radiator? Maybe the Eminence folks could send you something to match up with the the driver(s).

If you're close on the ports though, I would still play with the geometry trades and flaring first.

This. Radiators are great for small cabs. I hear the design side is tougher but haven't tried it myself.

 

[gmarcus]

If you want to mess around with a transmission line on the cheap. Get a 10 or 12" diameter sonotube (cardboard tube used for pouring cement footings), glue a piece of plywood to the top with a hole to mount your speaker. Then stuff it with fiber fill. Experiment with different stuffing densities and tube lengths. If you are really slick you can figure out how to make the tube length adjustable with some kind of sliding tube within a tube setup. Should keep you busy for a few days

 

[JRA]

Argh!

how's it going with the box?