I have built a 16ltr test cabinet for 6.5" drivers. I am fascinated by the behaviour one particular unbranded driver. It seems to be [British expression]: all fur coat and no knickers. It would look good on a Youtube video, bouncing around like it's having a serious affect on the Richter scale but it doesn't produce any actual bass. Of all the drivers I have laying around it has the weakest suspension.
Can somebody point me in the direction as to why it would be a disaster?
I can only guess that it was designed for a very small sealed cabinet.
Can somebody point me in the direction as to why it would be a disaster?
I can only guess that it was designed for a very small sealed cabinet.
Hi Surtsey!
I note you said this is an "unbranded driver".
So no clues whatsoever as to its origins?
If the enclosure supplies insufficient restoring force for this particular driver then you can expect large, and potentially damaging, cone excursions outside the linear operating region.
Your guess that this driver is designed for a smaller enclosure than your test cabinet may well be valid.
I note you said this is an "unbranded driver".
So no clues whatsoever as to its origins?
If the enclosure supplies insufficient restoring force for this particular driver then you can expect large, and potentially damaging, cone excursions outside the linear operating region.
Your guess that this driver is designed for a smaller enclosure than your test cabinet may well be valid.
Galu, if the cabinet is over-sized for the driver, that will increase efficiency (ie, it's easier for the cone to move), meaning more output.
My bet is the cabinet isn't sealed properly.
Chris
My bet is the cabinet isn't sealed properly.
Chris
Thanks to Galu and Chris for their theories. The test cabinet can be either ported or sealed. The two ports have removable cork bungs.
There is no air leak. If there was wouldn't it affect all drivers? (I have lots).
I have identified the driver. Unfortunately no specifications are available.
This is all I have:
There is no air leak. If there was wouldn't it affect all drivers? (I have lots).
I have identified the driver. Unfortunately no specifications are available.
This is all I have:
- Weight (kg) 1.83
- Magnet Weight (oz) 20 (567 g)
- Impedance (Ohms) 8
- Sensitivity (dB) 92
- Peak Music Power (W) 90
- Power RMS (W) 45
- Frequency Response (Hz) 40-5500
- Diameter (mm) 165
What are the tuning frequencies of your test cabinet, respectively closed, one port open, two ports open?
Could there be a low frequency rumble or feedback in the signal, do you use a high pass?
Could there be a low frequency rumble or feedback in the signal, do you use a high pass?
You might want to limit the amps low frequency output.
I used some small ported speakers (63Hz port tuning) with my synth once only to find out that if I weren't careful with the synths LF the speakers would produce HUGE excursion but no sound. The drivers in question were some nice Audax aerogel jobs.
I used some small ported speakers (63Hz port tuning) with my synth once only to find out that if I weren't careful with the synths LF the speakers would produce HUGE excursion but no sound. The drivers in question were some nice Audax aerogel jobs.
YOU have, 😉 , we are still in the dark.
So MEASURE it and post results.
You have not posted even the most basic of parameters: resonant frequency.
Fine, that´s "printed in the box" or "mentioned in the ad" data, we need some measurements now to do any kind of calculations.
If the driver Q is low and you put it in an oversized box, the perception of bass is lost, not gained.
From my experience with Tannoy drivers (Qts <0.25) they work best when box volume equals Vas with the port tuned to driver Fs.
Bass response almost disappears when in a smaller box or higher tuning.
They do need a bit of boundary gain though but then I never had a room that would allow for free-standing 300L boxes.
Bass response almost disappears when in a smaller box or higher tuning.
They do need a bit of boundary gain though but then I never had a room that would allow for free-standing 300L boxes.
In line with what Cal said, too large a box can produce a weak bass due to overdamping.
Putting a speaker into a large closed box lowers the frequency of resonance, but also lowers the Q.
Putting a speaker into a large closed box lowers the frequency of resonance, but also lowers the Q.
Okay, I'm going to admit defeat on this one. The behaviour of this driver (we'll call it the Soundlab driver) is somewhere between anomaly and enigma.
I have placed the Soundlab driver into a commercially manufactured Samsung cabinet of a similar displacement where it performs satisfactorily. I have installed the Samsung driver in the test cabinet - it performs admirably.
I can only conclude (for reasons unknown) the Soundlab doesn't like the test cabinet or the test cabinet amp.
I have placed the Soundlab driver into a commercially manufactured Samsung cabinet of a similar displacement where it performs satisfactorily. I have installed the Samsung driver in the test cabinet - it performs admirably.
I can only conclude (for reasons unknown) the Soundlab doesn't like the test cabinet or the test cabinet amp.
Depends which frequency you're looking at.
Below Fc (assuming closed box here), efficiency is gained as cabinet size increases. Of course, the lower Q means some efficiency can be lost towards the top of the passband.
Chris
I think I may have gotten to the bottom of it. It's the combination of that particular driver with that particular amp. Tested with sine waves, the Soundlab driver visually responds at 23hz. (None of the other drivers do). It is literally overwhelmed by attempting to output signals below the normal range. Connected to another amp the driver behaves well.
