IB power versus xmax question

[Vibeguy]

A long,long time ago I played bass guitar thru a Fender open backed 4 10 Bassman amp, 50 watts tube.I see that Parts Express has their 292-412 cheep 12 on sale.
Four of these in an open back box,the Qts is 1.54, Fs is 35,xmax is 3.5 mm.
At what power level do I run out of xmax for open E, 41 Hz?
Or would this be only suitable for guitar at 82 Hz?
Trade offs for U or H frame depth, etc.
Thanks!

[60ndown]

GRS 12PF-8 12" Paper Cone Foam Surround Woofer

that one ?

id guess you could run maybe 100 watts int 4 of them (open back) without issue.

would be loud enough for playing with a drummer (just)

[bjorno]

Originally Posted by 60ndown

GRS 12PF-8 12" Paper Cone Foam Surround Woofer

that one ?

id guess you could run maybe 100 watts int 4 of them (open back) without issue.

would be loud enough for playing with a drummer (just)

Hi,

Get acquainted with HR and you can reply more accurately.

b

[mashaffer]

Bjorno;

Why the two zero length, zero area segments between the front and rear chamber? I have never used HR to model OB before.

[60ndown]

Originally Posted by bjorno

Hi,

Get acquainted with HR and you can reply more accurately.

b

looking at your graph i see 100 w max?

[weltersys]

Originally Posted by 60ndown

looking at your graph i see 100 w max?

With a 50 Hz HP.
EG is voltage, voltage squared /impedance ends up with the speaker hitting Xmax at 9.5 watts, a whopping 100 dB at 40 Hz.

Open baffle can sound OK for musical instrument use, but they don't make low bass for squat.

[bjorno]

Originally Posted by mashaffer

Bjorno;

Why the two zero length, zero area segments between the front and rear chamber? I have never used HR to model OB before.

Hi,

Best way to model a H-Frame (OB) is in HR to invoke the CH(compound Horn flag) when in the main HR screen.

Result: The zero areas/segments are no longer valid. Here zero length and zero area means = labels not in use.

b

[bjorno]

Originally Posted by 60ndown

looking at your graph i see 100 w max?

No but if Eg = The input voltage is set to 28.28 V (Rms) into 8 Ohms, the applied power to the driver load is U^2/R = 28.28^2/8 = 100W.

See the picture where the SPL and cone excursion corresponds to 100W input.

b

[60ndown]

ok about 40 watts @ 41hz,

not 100.

optimism got the better of me again :/

[chris661]

Why not accept there's not going to be any low bass coming out of it, and add a high pass at ~80Hz instead?

It'd take 100w easily, and would give a lot of "tone" - harmonics instead of fundamentals.