Up for test is AudioFrog’s GB15 1.5″ Dome Tweeter.
It’s worth noting this review is based on mostly objective data. These drivers – as well as the others from the AudioFrog GB series speakers – include a LOT of installation hardware to make installs quicker and easier. I simply don’t have the time right now to really delve in to the facets of this, but I will include some of the hardware in the following pictures.
Small Signal Parameters
Results as measured via Dayton’s DATs measurement tool. Which is a very little handy tool to have. 😉
- f(s)= 1183.00 Hz
- R(e)= 2.92 Ohms
- Z(max)= 9.32 Ohms
- Q(ms)= 4.810
- Q(es)= 2.195
- Q(ts)= 1.507
Frequency Response and the following Harmonic Distortion measurements were taken using Dayton’s OmniMic measurement system.
The frequency response measurements below are on-axis (0 degrees) and off-axis (15, 30, 60 degrees), measured at 2.83v/1m.
The following HD graphs are done in the nearfield, emulating the 1 meter output of 90dB, 96dB, and 102dB in order.
Let’s take this step by step…
In terms of build quality, these are very nice. The body is made from some thick metal. There is a slew of install related optioned hardware provided (such as mounting tabs, screw ring to clamp the tweeter, removable grille that you can custom paint, etc, etc). Just extremely high build quality here.
The Fs shows an Fs of 1183Hz. Pairing this up with the distortion plots, it’s easier to get an idea of where an appropriate high-pass crossover point for a tweeter is. In this case, above 2khz, distortion is at about 0.50% THD at 96dB output and below 0.80% THD at 102dB output, so I’d say this is probably a safe low-frequency crossover with at least a 12dB slope.
While that may seem like a (relatively) high cross over point for a 1.5 inch tweeter, take a look at the average sensitivity above this point: 90.5dB @ 2.83v/1m measured. Compare that to the Gladen Aerospace 28mm tweeter I recently measured – which is only a couple millimeters smaller in each dimension – and you’ll see, while the Gladen looks like it can also take this same crossover point, that tweeter has an average sensitivity of approximately 87.5dB @ 2.83v/1m. The Gladen 28mm is just a hair more compact, by a couple millimeters in the various dimensions, but the AF has about 3dB higher sensitivity. So, in terms of output, I’d say the AF is slightly above the Gladen thanks to it’s similarly low distortion but 3dB higher output.
That’s a lot of talk about crossover point, so let’s look at frequency response which is more important to me…
You’ll notice a broad peak on the low end near resonance. Scan’s D3004/60000 has this as well, though steeper. I’m not saying it’s bad… I’m just doing some comparison against a well-liked product. There’s an off-axis dip And it’s worth pointing out here this testing was done without flush-mounting the tweeter (which is the same way I have conducted all of my tweeter tests over the past few years). As you can see the in the photo at the beginning of this review there is a pretty deep trough between the tweeter dome and the side of the housing that I believe is causing some of the combing pattern you see in the high frequency area. With that said, I prefer to look at on-axis to get an idea of the smoothness but I focus more on what happens off-axis to see how the trend behaves. Are the same bumps/dips there or do they differ quite a bit. According to my measurements the dip at ~10.5khz is due to a reflection from the dome center to the surround (this is a educated guess; doesn’t mean I’m right ;)). Overall the response on and off-axis trends well in relation to each other.
Overall, the on-axis response isn’t flat and it shows some combing in the high frequencies. The polar response (how the off-axis behaves relative to on-axis) tracks pretty smoothly. The sensitivity is 90.5dB @ 2.83v/1m which is pretty high and the distortion levels are very low. This tweeter should be able to handle a 2khz crossover point with the right slope (12dB or greater).
As extra, I also did some ‘grille on’ vs ‘grille off’ measurements below because I know some may wonder what effect there is. I DO NOT recommend using them in this manner because you surely run the risk of voiding a warranty claim if the dome gets damaged and being exposed makes it certain that Murphy will strike you… 😉
The following results illustrate the effect of the grille for both 0 degrees measurements and 30 degrees measurements, respectively.
As you can see, there is ~1dB additional output between 3khz-8.5khz with the grille on, but with the grille off, there is a maximum of ~2dB higher output above 8.5khz to about 16khz. So, it seems the grille impedes the high frequency output some amount while helps the lower tweeter range out.
PS: If you would like to help me keep up funds for testing, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page. Any little bit helps.