# An Enticing Marketing Story, Theory Without Measurement?

#### Thomas_A

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The individual woofer and tweeter step response of a time-aligned 2-way system (here 2nd order, both drivers positive polarity) must look like this

View attachment 35419

The blue curve is the resulting perfect sum step response.
The scale is a bit difficult too se the intertime difference p-p, is it possible to give an estimate?

#### UliBru

##### Member
Technical Expert
The scale is a bit difficult too se the intertime difference p-p, is it possible to give an estimate?
The time scale is in seconds. But IMO it is senseless to discuss about a p-p time as the resulting sum does not show up an intertime reference. Both drivers start at the same time but there is a delay to achieve the result.
The pulse responses look like this

#### Thomas_A

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The time scale is in seconds. But IMO it is senseless to discuss about a p-p time as the resulting sum does not show up an intertime reference. Both drivers start at the same time but there is a delay to achieve the result.
The pulse responses look like this
View attachment 35422
So there is around 1ms p-p intertime difference in this time-aligned response? It surely must be differences depending on the woofers covering range. If you measure the start of drivers action it will be zero. What I am getting at is that you need to compare relative differences between the drivers when comparing step response of time-aligned vs trad crossover. Or look at the impulse response. If there is a 2ms p-p difference between tweeter and woofer in a traditional crossover you need to compare that to the p-p difference between the same setup tim-aligned. The difference between these two numbers will be the actusl delay.

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#### UliBru

##### Member
Technical Expert
Once again: it does not make sense to discuss the p-p difference with individual driver measurements. If there are p-p differences in the total measurements this may be worth to discuss. In the given example of time-alignment there is no p-p difference in the sum.
BTW this kind of time-alignment is not achievable by just adding a delay to an individual driver or by e.g. shifting the tweeter forward/backward or by tilting the speaker.

#### Thomas_A

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Once again: it does not make sense to discuss the p-p difference with individual driver measurements. If there are p-p differences in the total measurements this may be worth to discuss. In the given example of time-alignment there is no p-p difference in the sum.
BTW this kind of time-alignment is not achievable by just adding a delay to an individual driver or by e.g. shifting the tweeter forward/backward or by tilting the speaker.
If you say so regarding that there is no point in relating the p-p it is so also for a traditional crossover. If would instead measure the start of the response you can also look at the impulse response. Easier.

#### krabapple

##### Senior Member
I've never found that helpful, personally. You cannot EQ a loudspeaker to fix problems that are not created by it, in this case, overly lively or dead rooms. A good loudspeaker, in a good room.. We listen 'through' rooms, but we can't ignore it either.
You can in once case, if I understand Dr. Toole correctly: when the recording itself is imbalanced. Then broadband tone control could help. But that's on a recording-by-recording basis, not something you'd leave 'on' all the time. And again, best predicated on having well-behaved loudspeakers, and room issues tamed, first.

#### TimVG

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You can in once case, if I understand Dr. Toole correctly: when the recording itself is imbalanced. Then broadband tone control could help. But that's on a recording-by-recording basis, not something you'd leave 'on' all the time. And again, best predicated on having well-behaved loudspeakers, and room issues tamed, first.
Sure, tone controls or a tilt function can be handy depending on what’s playing. Best to start of with a neutral baseline though.