Can a delay circuit be beneficial between bass and mids?

[madisonears]

Still fine tuning my active bass/midrange xovers. Mids to tweeter is passive, and needs no adjustment. I wonder if using all-pass delay stages will provide any benefit to the bass/mid transition? I do not have a way to measure phase of the drivers. The xover is 4th order LR @ 220 for 8" woofers, 2nd order BW @ 300 for the 4" mids. Amplitude looks good on paper, but I can hear something in the lower mids that's not quite right. Horizontal difference is between one and two inches, vertical is 28" C-T-C between the two most spaced drivers, M-T-M-WW configuration.

Has anyone successfully used delay between midrange and woofer?

Peace,
Tom E

[sreten]

Hi,

No, when your talking about 2" for wavelengths about 3-4ft.

Your problem might be related to lack of baffle step correction
and / or related to the mid units fundamental resonance, its
hard to say with full modelling details.

TBH your arrangements for BSC sound (sic) non-existen

Delay for bass to mid never, sometimes for mid to treble.

rgds, sreten.

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[dmfraser]

When I worked for a major pro audio speaker manufacturer we put a time delay of 83 micro seconds for every inch the LF driver's dust cap was forward of the MF driver's dust cap. And that has 83 micro Seconds delay for every inch in front of the HF driver's diaphram. We had the HF driver furthest back in the enclosure. So the way we made them was with no delay on the HF, delay on the MF and still more delay on the LF.

However, on home speakers, the LF is the furthest from the listener and the HF the closest. Therefore, one would delay the MF as needed and the HF a bit more.

The rule is 83 micro seconds per inch of front to rear separation between drivers.

[sreten]

Originally Posted by dmfraser

When I worked for a major pro audio speaker manufacturer we put a time delay of 83 micro seconds for every inch the LF driver's dust cap was forward of the MF driver's dust cap. And that has 83 micro Seconds delay for every inch in front of the HF driver's diaphram. We had the HF driver furthest back in the enclosure. So the way we made them was with no delay on the HF, delay on the MF and still more delay on the LF.

However, on home speakers, the LF is the furthest from the listener and the HF the closest. Therefore, one would delay the MF as needed and the HF a bit more.

The rule is 83 micro seconds per inch of front to rear separation between drivers.

Hi, pointless and inaudible at a typical bass / mid x/o point, rgds, sreten.

Driver offsets in typical 2 way bass/mid & treble speaker can be
compensated by making the x/o (acoustic curves) assymetric.

The phase shifts at bass to mid x/o are far higher than 83uS, and
any assymetry in the acoustic responses (very likely) will cause
far higher delays than that caused by driver acoustic offsets.
The effective acoustic offset of a driver may not be the dust cap.

[madisonears]

Is there an active circuit that will compensate for the phase shift, or do you believe it is not audible and therefore not worth attempting? I am not as worried about the physical driver offset (because of the low xover frequency) as I am about the phase shift between LR4 and BW2 I am using. Perhaps my initial post was not clear.

Peace,
Tom E