Maybe something to consider. Maybe I am wrong.
Your box is heavily stuffed. What we are achieving with stuffing closed boxes? We get apparently bigger volume due to lovered speed of sound. As you wrote Q fell from 0.90 to 0.74, what is not small step. So, as box is apparently biger, first standing wave is lower.
Try to model the box which dimensions giving Q=0.74 without any stuffing and calculate standing wave resonance. Could be close to your measured resonance.
Last edited:
@Zvu I have, and yes, it looks like it's at the top of the pile.
My only concern is the high Fs (95 Hz) and the rising distortion from 250 Hz upward shown in the datasheet. I know it's measured at 110 dB, but I’m not sure where distortion will start creeping in at lower levels.
I came across this set of measurements:
https://www.robsandiy.com/html/mid_bass/bms_5s117_8.html
Distortion appears to sit between 0.1–0.2% at 85 dB across the passband I’m interested in, which is great. The Fs there shows 100 Hz, slightly higher, but it's still a lot of money to commit to something that's unproven for my application. I'd love to see some polar measurements too.
What are your thoughts?
I did A-B the single speaker against one of my Genelecs and I didn't like it but then I was probabbly looking for problems.
My only concern is the high Fs (95 Hz) and the rising distortion from 250 Hz upward shown in the datasheet. I know it's measured at 110 dB, but I’m not sure where distortion will start creeping in at lower levels.
I came across this set of measurements:
https://www.robsandiy.com/html/mid_bass/bms_5s117_8.html
Distortion appears to sit between 0.1–0.2% at 85 dB across the passband I’m interested in, which is great. The Fs there shows 100 Hz, slightly higher, but it's still a lot of money to commit to something that's unproven for my application. I'd love to see some polar measurements too.
What are your thoughts?
I did A-B the single speaker against one of my Genelecs and I didn't like it but then I was probabbly looking for problems.
Callooh callay, data confirmation day!
I had to get to the bottom of the cube crisis. Or is it a driver crisis? Crisis of confidence? Either way, I ran some tests.
I measured the Faital Pro 5FE120 (Drivers A and B) and used a Peerless P830870 as a control and 3D-printed an adapter that let it fit in the same box (adorable). All three were measured in:
Turns out the oddity around 1kHz in the 5FE120 made the box resonance tough to spot. It was there all along, just buried in the chaos. What are the chances that the 5FE120 response throws a fit right on top of the resoannce? The P830870 makes it easier to see - the resonance shows up around 1.2kHz and is completely killed by damping.
As @danibosn rightly pointed out, the resonance shifts lower when the 5FE120 is in the box. My guess is the big magnet and general driver bulk change the physics.
I had to get to the bottom of the cube crisis. Or is it a driver crisis? Crisis of confidence? Either way, I ran some tests.
I measured the Faital Pro 5FE120 (Drivers A and B) and used a Peerless P830870 as a control and 3D-printed an adapter that let it fit in the same box (adorable). All three were measured in:
- Free Air
- Un-damped Box
- Damped Box (rockwool + melamine foam)
Turns out the oddity around 1kHz in the 5FE120 made the box resonance tough to spot. It was there all along, just buried in the chaos. What are the chances that the 5FE120 response throws a fit right on top of the resoannce? The P830870 makes it easier to see - the resonance shows up around 1.2kHz and is completely killed by damping.
As @danibosn rightly pointed out, the resonance shifts lower when the 5FE120 is in the box. My guess is the big magnet and general driver bulk change the physics.
- Faital Pro 5FE120
- Peerless P830870
Also...
I did a couple more distortion tests on the 5FE120 alone in the cube at 80cm.
One where the SPL peaks at 85dB and another at 95dB.
I did a couple more distortion tests on the 5FE120 alone in the cube at 80cm.
One where the SPL peaks at 85dB and another at 95dB.
Good for you in persevering and doing some more experiments.
Printing the holder for the Peerless driver was a great idea to help you see what was really going on.
From what I remember for distortion for the 5fe120 that looks right. I have a Clio pocket and it simply provides THD, 2nd and 3rd distortion measurements which is handy for a sanity check.
Printing the holder for the Peerless driver was a great idea to help you see what was really going on.
From what I remember for distortion for the 5fe120 that looks right. I have a Clio pocket and it simply provides THD, 2nd and 3rd distortion measurements which is handy for a sanity check.
Attachments
I purchased 5fe100 and 5FE120's to try out an idea approximately two and a half years ago, so quite some difference in build dates I imagine.
My cabinets are slightly larger than your cube, being an approx 8Litre reflex and my measurements were at a lower level than yours. So there is likely to be some differences. Your point about spikiness could be simply differences in chosen resolution. I usually try to aim for 12th octave smoothing.
My cabinets are slightly larger than your cube, being an approx 8Litre reflex and my measurements were at a lower level than yours. So there is likely to be some differences. Your point about spikiness could be simply differences in chosen resolution. I usually try to aim for 12th octave smoothing.