Introducing SPL Chart

[Chris_Allen]

Chris, or Bruce, is the AT measured in 1/2 space, 1/4 space or with cabin gain?

1/2 space, measured outside with the MCM. The same one as in the SPL Charts forum section.

[Futte]

Was there ever made an chart for the Omni12 with the 2 10" woofers ??

[DJPhatman]

Missing from the list= Table Tuba, Tuba 18

[Chris_Allen]

Here are the T60 charts:








Note: corner loaded variation!





I'll get the corner loaded variation sampled when I can.

[jason str]

Any chance to post the THT with the Dayton Classic 15 along with the others in the 24" version ?

[neverendingbeatz]

Is there anyway you can put a chart of:

Otop12
Otop212
Otop15
Otop215
Dr250
Dr280
Dr300

Thanks.

[DJPhatman]

Is there anyway you can put a chart of:

Otop12
Otop212
Otop15
Otop215
Dr250
Dr280
Dr300

Thanks.

These are already there....see the 1st post, on page 1 of this thread.

[Chris_Allen]

Missing from the list= Table Tuba, Tuba 18

I remember the T18 source chart not being very good, but there is no reason why the Table Tuba shouldn't be in the list.

I'll get that sorted when my computers are back in order.

[Chris_Allen]

Was there ever made an chart for the Omni12 with the 2 10" woofers ??

No, I don't believe that was ever sampled, possibly because it was very close to the 3012 output.

[BrentEvans]

Hey Chris,

When you get a chance, would you add a little detail to the list in the first post? I can decipher most of it, but it would be nice to have descriptions.


Thanks!

[Chris_Allen]

I'm sure I can manage that

[anomalous]

how about multiples? eg comparing a pair of T39 20" 3012LF against other stuff (eg a single T60)

[Chris_Allen]

The scaling of multiple cabs in terms of frequency response isn't linear, so it would be an estimation at best. The only effective way of doing it is to record more than one cab. To my knowledge, two 20" 3012LF T39's haven't been recorded using a trustworthy testing technique.

[anomalous]

The scaling of multiple cabs in terms of frequency response isn't linear, so it would be an estimation at best. The only effective way of doing it is to record more than one cab. To my knowledge, two 20" 3012LF T39's haven't been recorded using a trustworthy testing technique.

yeah, i figured as much, but I am surprised that noone has measured various multiples of the T39. i don't know anyone who has built just one...

I'd make the measurements myself, but i dont have anywhere quiet enough to get a reliable response plot.

for that matter, what would you consider a trustworthy testing technique? is there a BFM Forum Standard Method used for all the responses here, or are we just making assumptions that various people's test rigs and conditions are the same? (or do most of the plots come from just a small number of people?)

[Chris_Allen]

yeah, i figured as much, but I am surprised that noone has measured various multiples of the T39.

SPL Charts only give you a small snap shot of performance information. Perhaps the members having spent the time pouring over the charts to decide which one to build aren't that bothered about measuring them.

I'd make the measurements myself, but i dont have anywhere quiet enough to get a reliable response plot.

You aren't the only one. It's a complicated process where external environment features can affect results. Forum members over the years have often discussed how best to measure their cabs. With all the factors involved, the time required to do it, the space, the neighbours etc. you really need to know what you are doing - don't let this discourage you from having a go though.

I'd love to do it my self but I have nowhere to actually make the recordings (or how to do it!) I would be concerned that the 'plans' for measuring your cab would be more complicated and expensive than building a DR!

what would you consider a trustworthy testing technique?

Someone who could fully justify their testing method to the members of this board or a company who is liable for their measurement data.

is there a BFM Forum Standard Method used for all the responses here

Nope, but we assume Bill is consistant with his technique and that he knows what he is doing