Need advice on the execution of an aperiodic vent

[planet10]

I have seen articles in the past on tuning aperiodic enclosures and they always seem to focus on minimizing the impedance peak at resonance. Which I guess would also mean tuning for the lowest Q. Does this make sense ?

Yes. Althou the Q can go down with a peak at the same height but broadened at the base.

dave

 

[audiosteve]

Thanks Dave, I guess some of what I was curious about is this: How do you know when you have tuned correctly ? Will the impedance at resonance simply stop dropping or can it actually begin to increase ? I would think the former but am not sure. Thanks.

 

[IG81]

The Qtc cannot go lower than the driver's Qts for certain. The way I did it, I did not look to maximize the impedance curve's flatness, but stopped when I had the desired Qtc, 0.65-0.7 was my aim. I guess at some point, if you try to go too far and remove too much resistive material, you will start to see a bass-reflex behavior, that would be my guess.

IG

 

[planet10]

If the lower BR peak starts to return that is certainly an indication that you are going too far.

Qt = 1/(1/Qe+1/Qm).

The aperiodic port is affecting Qm.

Under voltage drive Qe dominates. Under current drive Qm dominates.

dave

 

[audiosteve]

Thanks guys. That all makes sense.

 

[IG81]

Thanks guys. That all makes sense.

I'm learning as much as you here!

I placed the speakers better in my room and listened to some well-recorded/mastered stuff, Patricia Barber, and it sounded really good, even with no EQ (used to simulate BSC). Tried some dance music as well, David Guetta, and they did well enough; but I did hold back on the SPL to give them a chance. Looking forward to try other stuff I have on them!

IG

 

[IG81]

That is most of the Philips. The others would be other vintage drivers i sold during my vintage driver period.

dave

BTW, did you ever come accross any AD9710, wether in commercial or DIY boxes during this period?

IG

 

[planet10]

No. But i did go thru 3 pair of the similar 12" that came out of the ceiling of a federal government office,

dave