Basszilla Lite

[jim]

Hi,

I'm thinking of a sort of Basszilla kind of speakerproject but since
the original uses rather expensive units this would be a Lite-version.

The speakers I've in mind : Fostex Fe206e or Fe207e and the Beyma 12BR70 woofer. The Fostex units have a 95-96dB sensitivity (but 93-94dB with notch filter) and the woofer has a 94,5dB so they would combine good.

Any further recommendations ??

Thanks,
Jim

 

[Flemming J P]

Hi

I doing a project with FE206E in OB and JBL2225 in a sealed box for bass.

To avoid using the notch filter I've titled the OB 15 degress (haven't had the chance to measure it yet).

The JBL are 97db sensitve and in my current setup they need a pretty big boost to keep up with the Fostex's.

I think I've read somewhere that OB gain +3 db (because of the back wave).

Currently I'm using a active XO at 180hz 12db. I started off with XO at 100-120 6db, but the fostex sounds way better when they have less bass to deal with.

So no real answers, yet.

 

[GM]

Hmm, using the T/S efficiency formulas to get a more accurate nearfield LF sensitivity rating, the FE206E is ~94.23dB/W/m (the target for the notch filter) and the 12BR70 is 93.04dB/W/m. As JR implies, the 12BR70 would need to be boosted ~0.2dB + 3-6dB depending on how much BSC is required, or the FE206E shelved this much. Neither is a good plan, though boosting the LF is the lessor of two evils if it doesn't go terribly non-linear. If it does, then a mix of boosting it and shelving the HF will be required to find some hopefully acceptable balance of dynamics.

Adding another 12BR70 and rolling it off as required to act as the BSC solves the problem if the budget permits. Due to its displacement capability, a bipole layout is preferred to ~cancel out vibration, that, or a really massive cab construction.

GM

 

[jim]

Fostex in sealed cabinet ?

Would it make any difference if I place the fullrange speaker in a little sealed cabinet placed on top of the bass enclosure ?

What do you mean by BSC ?

Jim

 

[Nuuk]

Would it make any difference if I place the fullrange speaker in a little sealed cabinet placed on top of the bass enclosure ?

YES I have been experimenting and even a deeper cowl at the rear of the speaker removes some of the open-baffle 'magic'.

 

[Variac]

The FE 206 has a good reputation but I haven't heard it.
I think it is a great choice for this project.

I have also found that my Fostex 208 needs to be attenuated quite a bit to match my woofer. I also used a cheaper bass unit so I can only assume that the real Basszilla works OK.

Keep the bass driver and port close to the floor if you are using one amp. This will give you more bass boost. I'm going to bi amp mine so I thought I'd be OK with them higher, but now I'm thinking that I will not only lost bass, but that the room gain SLOPE is also important. In the upper bass, the Fostex helps out a bit, but in the lower and mid bass, you need lots of room gain to match the upper bass which is a combination of the Fostex and the bass driver.

Where did you get your Beyma?

 

[LaMa]

Beyma is available in the Netherlands from:

bmm (website also in English)
and in belgium from Aqua Blue

Both supply to foreign countries.

 

[jim]

Baffle step

Hi GM,

Adding another 12BR70 and rolling it off as required to act as the BSC solves the problem if the budget permits. Due to its displacement capability, a bipole layout is preferred to ~cancel out vibration, that, or a really massive cab construction

Do you mean that each 12BR70 should be filtered different in order to compensate for baffle step ?

Jim

 

[GM]

No, they're wired in parallel with one having a low DCR inductor in series to roll it off at the appropriate point, or you can wire them in parallel and use digital EQ to adjust them both.

GM