Rising response

[Bas Gooiker]

Temperatures are rising outside and spring seems to have finally started. So i can go back to building without freezing to death. Tops are next.

I have read all the plans over and over this winter and im wondering about the rising response mentioned. There doesn't seem to be a fixed amount of rise. The 2512's response starts to rise from 900hz until it reaches a +10db peak at 2.5khz. The Delta pro 12 has just a small 5db hump between 2.2 and 3khz. The "rising" differs quite a bit between all the recommended drivers for the tops.

What makes a driver fit in the "rising response" category? How much of an increase in sensitivity should there be, and at which frequency band?

I am not looking for an alternative... just trying to understand the theory and the way it is used in these designs.

[Bill Fitzmaurice]

What makes a driver fit in the "rising response" category?

It's not flat, or worse, rolling off.

[Grant Bunter]

Bas,
I did look through a whole heap of drivers before building (in the end what I did was waste a lot of time in terms of results, but did get to understand response charts a bit better), and rising response was something that appeared to be missing in nearly all except the recommended drivers.

Some would go close, only to plateau out at say 2K if it was called for for a rising response to 2.5K for a particular design.

I don't think it matters terribly much to quantify it. You just want to see a chart that continues to generally trend upwards to the specified point.

Now you might think that rising to 2K when you want a rising response of 2.5K is no big deal, but since most of the piezo loaded cabs crossovers have a corner frequency of 2K, that little extra from 2 to 2.5K means a little extra sensitivity around the crossover point.

I'm sure Bill has taken the rising response characteristics into consideration in design and modelling in his cabs. Essentially, if it isn't there, then it has to be put there with (more) EQ.

That's my take on it, but I've been wrong plenty of times before...

[Bas Gooiker]

Thank you for the quick reply Bill.

The rise in response should ideally continue until after the crossover frequency?

[Bill Fitzmaurice]

Thank you for the quick reply Bill.

The rise in response should ideally continue until after the crossover frequency?

Ideally it would peak right at the crossover frequency.

[Bas Gooiker]

@ Bill, thanks again.

@ Grant.
Thank you for taking the time another very extensive answer. Both your and Bills answer where just confirmation of what i thought for myself.
I don't care about the time wasted, i've spend numerous hours checking datasheets whenever i was bored. Its not about finding a cheaper replacement, as the Eminence midbass drivers are among the cheapest you can get.

Now you might think that rising to 2K when you want a rising response of 2.5K is no big deal, but since most of the piezo loaded cabs crossovers have a corner frequency of 2K, that little extra from 2 to 2.5K means a little extra sensitivity around the crossover point.

Would this mean it is of no use on Cabs with the CD option?

[Bill Fitzmaurice]

Would this mean it is of no use on Cabs with the CD option?

No, just that for perfect matching their responses would peak at the crossover frequency. And keep in mind that the CD option may also cross at 2kHz, the same as the piezos.

[Grant Bunter]

^ Haha!

Funny you say that, I was just thinking much the same myself.

However, it then occured to me that the crossovers aren't like brick wall limiters, so, while the frequencies in the mid driver above the crossover point may be somewhat tamed, they aren't totally squashed, but will fade out as per their response chart. This reinforces the mids from the CD's (and also applies to piezo's)...

edit: Bill put it better, as usual...