Saturday, January 9, 2016

New Folded Corner Bass Horn - New Driver Testing

A couple of days ago, a Tymphany model FSL 1225R02-08 guitar speaker I ordered from Parts Express arrived.  Here is an image showing the Tymphany next to the New Folded Corner Bass Horn throat.


New Folded Corner Bass Horn - Tymphany Speaker
New Folded Corner Bass Horn - Tymphany Speaker
I mounted the new speaker, right out of the box, to the horn, then placed the back chamber over it and sent some white noise to it to get an idea of the frequency response.  I got the following plot using an FFT app running on the iPad.


New Folded Corner Bass Horn - Tymphany Speaker
New Folded Corner Bass Horn - Tymphany Speaker
You can see that the response is not particularly flat in the bass region, or anywhere else for that matter :)  By way of comparison, here is an image of the plot of the New Folded Corner Bass Horn with KLH CL-3A woofer installed.


New Folded Corner Bass Horn - KLH Woofer From CL-3A
New Folded Corner Bass Horn - KLH Woofer From CL-3A
This one is not so "flat" either but I think the KLH plot looks better in the bass region.  Well, what is happening here is the new Tymphany speaker has not been "broken in" yet.

Today, I set up to measure the free-air resonance of the Tymphany right out of the box new.  I used a signal input level within my accustomed listening level, about 0.001 Watt, and recorded a resonant frequency of 83.6Hz.  Well, the Tymphany specification for this is 59.1Hz but that is on a speaker that has been broken in.  I set up a sine wave signal source at about 9V rms at 30Hz and let it run to the speaker for 2 1/2 hours.  After that, I checked the resonance again and got 67.7Hz.  After another 2 1/2 hours, the resonance is down to 59.6Hz when measured at my accustomed maximum listening level of about 0.001 Watt.  Putting a little more power to it with 3.122 Volt rms across the speaker and 57.3 milliamperes rms running through the voice coil, I get a resonance of 56.3Hz.

This is a great example of how important it is to break a new speaker in.  It is the only way you will get close to the manufacturer's specification.  This is particularly important if your speaker is horn-loaded.  If the most power I ever put into this speaker were only 0.001 Watt, it would probably never reach rated specification, at least with regard to free-air resonance.

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