2012H enclosure size?

[Lancer]

2012H in 0.5 cu ft sealed box.

[Lancer]

Add in the Parts Express 1.5 mH 14 AWG air core

[tomp787]

Hello,

There are cases where the DCR of the series inductor can be used to your advantage. It effectively raises the Qes of the driver thereby changing the low frequency rolloff. Here is the equation:

Qes 2 = [ Qes 1 x (Re + Zo)] / Re

Where:
Qes 1 is the driver's original Qes
Qes 2 is the new Qes
Re is the driver's VC resistance
Zo is the amplifer's output impedance (or series R)

Tell us what happens when you model some inductors with higher DCR. My guess is a higher DCR (cheaper?) inductor will bring up the low end response but maybe the dcr is insignificant? In either case you may win.

Regards,
Tom

[Baron030]

Thanks, Lancer
Call it a brain fart, But, I just could not figure out to how to attach the chart last night. Somehow, I just knew it was going to be easy, once you can get a handle on it.
As I stated before, I chose the 1.50mH value because it appeared to give me the flattest response over the 400Hz to 1,000Hz range for my project. And that I will be using this inductor with an electronic crossover network. For those who are planning on using a passive crossover network, the 1.50mH coil will not work. Instead, you will need to design a network with a dropping response to compensate for the 2012H drivers rising response. Since, a 1.5mH coils is equal to a -6Db per octave low pass filter with a 850Hz crossover point. That should give you a clue as to where to start on a passive crossover network design.

http://audioheritage.org/vbulletin/a...tid=9066&stc=1

[stevem]

Strictly from a subjective point of view, I'm liking the ported enclosure a bit better than the sealed one. It sounds a little more "relaxed", although it appears about the same within it's pass band (with my admittedly coarse measurements).

I also find it interesting that in a Stereophile review of the Wilson Maxx something, they are also porting the midrange enclosure, and the port doesn't contribute much output in their design either. I'm going to give the 1.5 mH inductor a try too, I must have a couple of that value around here somewhere.

[stevem]

By the way, I agree with you Baron that the rising response of this driver is unacceptable. From the begining I have used active EQ to flatten the rise, and also a boost at low end to flatten the response to just below my crossover frequency of 300 Hz. I found that this "splitting" the EQ instead of starting at a lower frequency and using a lot of cut only (but with global gain to bring the level back up) seems to sound a little better in my system.

[GordonW]

This "splitting" of the EQ, ie, slightly boosting the lows and cutting the highs, does make sense, from two standpoints:

1) The EQ is probably cleaner, nearer the "center" of its range... this is frequently the case with these types of devices. EQs tend to behave quite a bit better, when they're not asked to make extreme changes to a signal.

2) The phasing/damping is probably improved, overall. Boosting the bottom end will effectively reduce some of the damping, in what is almost always an over-damped bottom end response with these drivers (unless they're in a TINY enclosure). This will restore some of the transient rise behaviour (ie, improve the time response of the driver to midbass transients)... ie, the driver will react "faster" to transients in the 300 Hz range or so, bringing its time-domain behaviour in that range to something nearer its time-domain response at other frequencies above that.

Regards,
Gordon.

[Rudy Kleimann]

Something else that factors in to this comment: Phase shift by the EQ itself. All analog Equalizers introduce phase shift as their filters are activated to introduce an output level change within their passband. the more EQ, the more phase shift.

Not to mention the ragged frequency response curves between the center frequency of each EQ filter when large EQ adjustments are made yields a FR curve that looks more like a rollercoaster track when running through several adjacents bands on the EQ.

Always try to spread your EQ'ing equally above and below the mean (Zero) level, i.e. start a little above 0, and end up a little below 0 on the other end of the long slope you are trying to make with it.

[Baron030]

Well, I have been very busy for the last few months. But, I have finally had the time to do some testing of the 2012h drivers. The charts below were created by using the following equipment and procedures. A DBX RTA-M microphone was used with a PreSonus tube preamp and a Rives Audio Test CD. Unfortunately, the Rives CD contains sine wave test tones spaced 1/3 octave apart and not 1/3 octave filtered pink noise. Sine wave test tones are very sensitive to room resonances, while 1/3 octave filtered pink noise will tend to average out some of a room’s resonances. As a work around for this problem, I made a dozen measures varying the placement of the drive in the room and varying the distances between the diver and the microphone. In the future, I am going to track down a CD of 1/3 octave pink noise and save myself a lot of time. What really surprised me in testing was seeing a roll off above 1000 Hz. The published response curve of this drive clearing shows a rising response above 1000 Hz. As you can see, the drive does have a nasty peek around 800 to 1000 Hz. Without any equalization, this peak can easily be heard during listening tests. To provide some equalization, I have experimented with using a 1.50mH coil. As you can see, as a very simple equalizer, the 1.50mH coil works fairly well. But, I do see the need for adding a resister and maybe a capacitor as well, wired in parallel with the coil to really smooth out this driver’s response.
http://audioheritage.org/vbulletin/a...id=10246&stc=1

http://audioheritage.org/vbulletin/a...id=10247&stc=1
Baron030

[duaneage]

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Chinese money is called Remimbe, loosely translated as The Peoples Money. If only that were true.
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And that means "Beautiful Land"