Group delay

[wu36ca 10+ year member]

I believe this is what causes that muddy sound. What is considerd too high group delay?

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[tcguy85 10+ year member]

whats group delay? i'm pretty savvy with car stereo but i have no idea what group delay is.

 

[Volenti 10+ year member]

Group delay is the difference between a driver receiving an electrical signal and the sound being emitted by the driver/box.

There really is no set level for acceptable GD since it's audiability varies with frequency, the lower you go the more GD you can get away with since we have trouble getting timing ques from very low frequencies. This is one of the reasons why people use very low tuned vented enclosures, you push the group delay peak so low in frequency it becomes difficult to detect.

Muddy sound is more due to too high of an enclosure Q (Q is resonance quality, a lead pipe has a very low Q while a bell or tuning fork has a very high Q) a high Q enclosure will "ring" like a bell after the original signal has stopped, this ringing will smear closely spaced sounds causing a muddy sound. Group delay is related since a high Q enclosure will have a higher GD than a lower Q enclosure but it is a symptom rather than a cause.

If I had to put numbers to it I would keep GD below 5ms for 100hz-75hz, below 10ms for 75-50hz, below 20ms for 50-30hz, and below 50ms for 30-20hz