Q Control Hsu VTF Series

[Pogre]

I know little about the Q control I have on my subs. Right now they're set at ~0.6-ish. I've experimented and am having trouble detecting any difference (by ear). I've learned along the way that some things are subtle and sometimes you have to know what to even listen for. Is there just not much difference from one end of the dial to the other or do my ears need a little training?

I know a higher Q tightens things up when I make adjustments in my DSP to a particular band where a lower Q spreads the adjustment out more across the fr. Thus lower Q in a subwoofer would be a looser response and a higher Q more tight and punchy?

 

[shadyJ]

In practice, the Q control just allows more low-end output. If you want to hear the difference, run a pink noise tone, that is probably your best bet for perceiving a difference. As for 'tightness,' the Q control doesn't change group delay significantly, so it's not a filter. If you add a filter to create the same effect on the response, you would see a spike of group delay.

Higher Q will loosen things up and lower Q will tighten things up. However, and TLS Guy will probably disagree, but the Q of a low-frequency speaker system is not an audible property outside its effects on the frequency response. It's not a matter of 'tightness' in bass either. Here is the group delay of a high Q subwoofer:

... and it is not bad. Pretty much below 10ms above 40 Hz and below 20ms above 30 Hz. The audible consequence of the system Q will be heard in the frequency response, and it will be obvious.

 

[Pogre]

In practice, the Q control just allows more low-end output. If you want to hear the difference, run a pink noise tone, that is probably your best bet for perceiving a difference. As for 'tightness,' the Q control doesn't change group delay significantly, so it's not a filter. If you add a filter to create the same effect on the response, you would see a spike of group delay.

Higher Q will loosen things up and lower Q will tighten things up. However, and TLS Guy will probably disagree, but the Q of a low-frequency speaker system is not an audible property outside its effects on the frequency response. It's not a matter of 'tightness' in bass either. Here is the group delay of a high Q subwoofer:

... and it is not bad. Pretty much below 10ms above 40 Hz and below 20ms above 30 Hz. The audible consequence of the system Q will be heard in the frequency response, and it will be obvious.

I knew you'd have something for me! I almost summoned you in the OP even, lol.

That is exactly what I was wondering, and I had it backwards. So if I were having audible issues in my fr adjusting the Q may help in some cases, but not all. Is there a preference or average best? My guess is it depends on the driver and it's behavior in a given box. Just curious if there's a universal "80 hz crossover" Q for subs.

*Edit: Good lord, that sub build!

 

[ryanosaur]

*Edit: Good lord, that sub build!

Krikey, Mate!

 

[shadyJ]

I knew you'd have something for me! I almost summoned you in the OP even, lol.

That is exactly what I was wondering, and I had it backwards. So if I were having audible issues in my fr adjusting the Q may help in some cases, but not all. Is there a preference or average best? My guess is it depends on the driver and it's behavior in a given box. Just curious if there's a universal "80 hz crossover" Q for subs.

*Edit: Good lord, that sub build!

Yes, the Q control on the Hsu subs just tempers the low end. It's helpful if you are getting too much gain on the low end. It's purely a matter of preference of how much deep bass you want.

Everything affects the system Q. And there are different Qs that add up to the system Q; there is the mechanical Q and electrical Q, the Qms and Qes respectively. They add up to the system Q, the Qts. Obviously the Q control on the Hsu subs are only modifying the electrical Q of that system.

As for universal Q parameters, many subs try to go for a system Qtc (Qtc is the overall Q of the driver) of .707 which usually yields the flattest response. But some subs will go for a Q of .5 is is called critically damped. Cheaper subs may go for a high Q of like 1 or above which will have a very peakish response. These can be boomy 'one-note' wonders.