Need a little engineering advice

[dhomer]

I'm currently modeling a 2-10 wedge. It will be driven w/300 watts, and the guy I'm doing it for requests a strong bottom end. The Beyma 10LW30/N will handle the power fine, but models a dB or so shy in the first harmonic area. This is the leading candidate.

However, there's other drivers touted for electric bass (Beyma 10G40, Faital Pro 10PR300, and Faital Pro 10TF500) that to me model a bit strange... they drop off around 100Hz. On paper that means the first harmonics on the lower strings won't be very prominent.

Just trying to grasp the concept, would those drivers work as well or better in this application? Before anyone asks, I have modeled the Eminence neos.. Exceeds xmax about half-power..

[washburn_it]

That's the same problem I had when modeling several speakers for my 2x10".
I tried Beyma, Faital Pro, B&C and all of the good candidates had that kind of "drop" around that frequency.
But not only the 10" but also with 15" or 12", but not with Eminence drivers.
At the end I chose two Legend BP102 but the cab is "displacement limited" to 250 Watt.
I Would like to know too why that strange drop off...

Regards,

Roberto

[billfitzmaurice]

Originally Posted by washburn_it

I Would like to know too why that strange drop off...

Low Qes/Qts. There's nothing at all strange about it, that's exactly what one expects with Qts less than .35.

[washburn_it]

Originally Posted by billfitzmaurice

Low Qes/Qts. There's nothing at all strange about it, that's exactly what one expects with Qts less than .35.

Good to know it...you never finish to learn !

Then such kind of speakers are better suited for a mid-bass cab?

[rpsands]

Deltalites, but they're gonna be brutally expensive right now.

Sounds goofy but I'd just use betas for this application right now.

Or buy BFM's Wedgehorn 10 plans!

[Sundogue]

The problem with any cab design (especially a 210) is you are going to have to live with trade-offs.

If he wants strong bottom end, then a simple full range 210 ain't going to give him that because anything that extends high won't go as low and visa versa. If you design the cab to have room for a dedicated mid driver, then use BP102's for the lows and something like an Alpha 6 for a mid.

The BP102's will go low and even if you design the cab that bumps the upper bass more at the expense of true deep lows, they have an xmax of 6.2mm which is pretty high for a 10" speaker and you can get stronger bottom end than another full range ten. Problem is, because they can do so well in the lows, they suffer in the upper mids and highs. Can't have it all in one speaker I'm afraid.

If you are designing a 210 with strong bottom end being the goal, you really need to look at the excursion charts for whatever speaker you choose in that cab and go from there.

[Arjank]

Originally Posted by Sundogue

Can't have it all in one speaker I'm afraid.

Yes you can, the Oberton 10B200.
It just sucks that one can still can not buy Oberton in the US.

[dhomer]

Kinda makes me wonder how many hoops one would have to jump through to get those Obertons direct.. BP102 would fill the bill, but I can't see a 5cu.ft wedge...lol... Kinda what I figured, the charts don't lie.. Will continue to research, but I think that Beyma driver's gonna be the project.. Thanks guys..

[dhomer]

Worked over the ol'ISD w/a stack of data sheets, and it appears we have two "winners".. The Beyma 10G40 and the Beyma 10MW/ND model virtually identical in the same box/tuning. The only difference is about 10 pounds and $80.. Still awful pricey, but they do the job w/out displacement limitation. Oberton modeled well too, but availability eliminated that choice. The Deltalites actually modeled the best out of the bunch, but the box would have had to be a lot larger than what a floor wedge should be. Rest of 'em either didn't have the low-end extension or exceeded xmax at half power or less.. Now to really get busy....lol....

[Arjank]

Originally Posted by dhomer

Worked over the ol'ISD w/a stack of data sheets, and it appears we have two "winners".. The Beyma 10G40 and the Beyma 10MW/ND model virtually identical in the same box/tuning. The only difference is about 10 pounds and $80.. Still awful pricey, but they do the job w/out displacement limitation. Oberton modeled well too, but availability eliminated that choice. The Deltalites actually modeled the best out of the bunch, but the box would have had to be a lot larger than what a floor wedge should be. Rest of 'em either didn't have the low-end extension or exceeded xmax at half power or less.. Now to really get busy....lol....

Get one of those Beyma's
Don't use them deltalites, I tried them and they are not worth the money.
The deltalites are a drive into fartcity..

[mmbongo]

Originally Posted by Sundogue

If you design the cab to have room for a dedicated mid driver, then use BP102's for the lows and something like an Alpha 6 for a mid.

So putting a low pass crossover on a speaker will allow it to produce lower frequencies than it would running full range?

[dhomer]

Originally Posted by mmbongo

So putting a low pass crossover on a speaker will allow it to produce lower frequencies than it would running full range?

It won't make the driver go any deeper, but it will divert higher frequencies to drivers that better handle the range and improve dispersion. Specifically, the BP102 has a nasty response dip around 500 Hz, so this driver should not be allowed to run full range.. Low end response is determined by driver parameters and box/port design, not crossovers..

[Sundogue]

Originally Posted by dhomer

It won't make the driver go any deeper, but it will divert higher frequencies to drivers that better handle the range and improve dispersion. Specifically, the BP102 has a nasty response dip around 500 Hz, so this driver should not be allowed to run full range.. Low end response is determined by driver parameters and box/port design, not crossovers..

^ What he said. Nothing will make a speaker do anything it isn't already capable of. All one can do is design a cab (along with the crossover, tuning, etc.) to accentuate that which the speaker's strong points already serve.

[billfitzmaurice]

Originally Posted by Sundogue

^ What he said. Nothing will make a speaker do anything it isn't already capable of.

Au contraire, there's all sorts of response shaping that can be done with passive components, including increasing system sensitivity at both the low end and high end of the resulting passband. What you can't do with passive components is to increase the driver's low frequency output capability, as that's determined by displacement, but that can be tweaked in a major way with the cabinet design.

[dhomer]

Now that I have the design pretty much finalized, the next issue is to correctly calculate the shelf port this will have. I know ISD isn't capable of making that correction. I have read somewhere a quick and dirty adjustment is to subtract half the port height from the shelf. I know the correction factor is 2.227, but the equation I found on another site/thread doesn't compute... We solve this mystery, a cab is born...lol...

[Sundogue]

Originally Posted by billfitzmaurice

Au contraire, there's all sorts of response shaping that can be done with passive components, including increasing system sensitivity at both the low end and high end of the resulting passband. What you can't do with passive components is to increase the driver's low frequency output capability, as that's determined by displacement, but that can be tweaked in a major way with the cabinet design.

Obviously one can make a speaker behave a bit stronger in one area or another by how the cab and it's components are designed, but...my point was...like with a BP102 for example...nothing you do with it is ever going to make it shine in the upper mids or highs.

Because it is what it is. Were that not the case one could use any old driver and just shape it to do your bidding.

[Arjank]

Originally Posted by dhomer

Now that I have the design pretty much finalized, the next issue is to correctly calculate the shelf port this will have. I know ISD isn't capable of making that correction. I have read somewhere a quick and dirty adjustment is to subtract half the port height from the shelf. I know the correction factor is 2.227, but the equation I found on another site/thread doesn't compute... We solve this mystery, a cab is born...lol...

So which drivers are you going to use?

[dhomer]

Both of the Beyma drivers model "identically" in a 4000cu.in. box tuned to 53. Choice will depend on the fellow's preference between weight and cost. I found an online calculator last night, just have to convert the slot port to a circular diameter for the equation to work. It's getting there...lol...