Measuring new drivers with Dayton DATS V3 - driver break in question

[Pygmy]

So I just received my Dayton DATS V3 kit, and I've just measured my new - straight out of the box - Tang Band W6 1139SIF drivers.

But - as mentioned, they are new and I just unpacked them.
So I figure the parameters might change after break-in.

I don't have a box to put them in yet, so I'm wondering what's the preferred way to break in new drivers without any accompanying box.

I could hook them up to my amplifier without them being in a box, without any crossover, facing eachother (one driver with inverted phase) and play a low frequency signal.

Would this be okay or is it a bad idea to hook the drivers up to my speaker wires directly?

And if it is okay, what frequency / how loud / how long?

 

[Pygmy]

Went ahead and connected one W6 1139SIF to my speaker wire.

Sent 30 and 40 Hertz tones to it for 30 minutes.
Then "massaged" the driver by just manually pushing it in really deep a few times - something I read on Troels Gravesen's pages somewhere ;-)

Measured again. All parameters staid the same, except Q(ms) which dropped from 4.95 to 4.25.

Gave the driver some time to rest, and measured again. All parameters still the same except Q(ms) - which went up again from 4.25 to 4.6.

After some time and a few measurements Q(ms) seems to settle around 4.6.

Do with that as you will

 

[AllenB]

Running at driver resonance is interesting because you decrease the dissipated heat required to get the cone to push Xmax.

Anyway, breaking in has been shown to have less effect on the needed box size than it would appear by looking at specific parameters.

 

[Pygmy]

So does breaking-in matter when measuring drivers with DATS, or can I assume that the measurements taken with new drivers are "good enough"..?

 

[AllenB]

Some say 24 hours gets you close.

If it helps to put my opinion into perspective when building closed boxes, I don't measure anything. I just do some quick calculations in my head and build a box. Unless I have no specs to go on such as a random driver, then I'll measure.

Some knowledgeable members have covered the partially self-balancing nature of TS parameters I alluded to, off-hand I recall GM is one of them. I would suggest you could put your mind at ease by understanding their teachings.

 

[metzb1]

So does breaking-in matter when measuring drivers with DATS, or can I assume that the measurements taken with new drivers are "good enough"..?

After measuring several woofers before and after break-in, I always break in before taking final measurements. Parameter changes vary by manufacturer, but it happens often enough that I just always break in as standard practice now.

 

[Mattes]

Hi Pygmy,


let the drivers work somewhere near Fs for 24 hrs. Face to face opposite polarity minimises noise. Don´t exceed Xmax. After that, let them cool down a little bit, then measure.
Important is a measuring device that clamps the driver rigidly while measuring, BUT keeps the driver away from any reflective surfaces (somewhere on Wolfgang Klippels site there´s a nice example), of course not made from metal...
Having the drivers laying on your workbench will not give you good results...


All the best


Mattes

 

[Pygmy]

Hi Pygmy,


let the drivers work somewhere near Fs for 24 hrs. Face to face opposite polarity minimises noise. Don´t exceed Xmax. After that, let them cool down a little bit, then measure.
Important is a measuring device that clamps the driver rigidly while measuring, BUT keeps the driver away from any reflective surfaces (somewhere on Wolfgang Klippels site there´s a nice example), of course not made from metal...
Having the drivers laying on your workbench will not give you good results...


All the best


Mattes

All right, so what exactly will change after doing that?
And how will it affect my calculations?

 

[hifijim]

The driver measurements will probably be much closer to factory spec... but whatever the measurements are, you can be confident that they will be stable from that point forward.

 

[celef]

Some says that break in should not be done with a single freqency and steady state, it is better to use music as signal as this makes less stress on glued parts

 

[Sonce]

Pink noise is the best.

 

[barackuda]

I have just measured my two modified 2226H drivers.
Be interesting to see a measurement when its siting on a bench, or when its hung up somewhere or just in free space suported by the magnet....
Results are very good for me, but I need to build a box to measure Vas and the Mms with added mass

 

[Pygmy]

Some says that break in should not be done with a single freqency and steady state, it is better to use music as signal as this makes less stress on glued parts

Troels Gravesen writes on his site that he sometimes massages / stretches the spider by hand.

 

[hifijim]

Troels Gravesen writes on his site that he sometimes massages / stretches the spider by hand.

I have tried this, and it seems to help...

My preferred break-in signals for woofers is 1/3 octave pink noise. I have tracks from an old test CD with 30 sec of 1/3 octave pink noise at 20, 25, 31, 40, 50, and 62 Hz. I just repeat these over and over again... I used to use a CD player on repeat, but now I just use a laptop. 2 Volt RMS is usually enough.