I apologize if I have overlooked it, but I couldn't find measurements of the Cubo Kick 15 design anywhere, so I thought I'd post them here.
The bin has been built according to the available plans on freespeakerplans.com, but with 18mm poplar multiplex, which was on hand. This makes it VERY light, but it needs some more reinforcements (which we still have to implement). It is loaded with the 18 Sound 15ND930, 8 ohms.
Measurement is with 2.83V at 1m, mic on the ground, measured outside, 2pi.
THD seems a little high 😱. We'll reinforce the cab and do some more measurements.
The bin has been built according to the available plans on freespeakerplans.com, but with 18mm poplar multiplex, which was on hand. This makes it VERY light, but it needs some more reinforcements (which we still have to implement). It is loaded with the 18 Sound 15ND930, 8 ohms.
Measurement is with 2.83V at 1m, mic on the ground, measured outside, 2pi.
THD seems a little high 😱. We'll reinforce the cab and do some more measurements.
Attachments
I haven't seen measurements of Cubo Kick 15's final version myself. That THD could definitely be lower. I've heard people saying that they use dampening material in the rear chamber (all walls without restricting air flow) successfully to improve sound at high output, might be related. It would be interesting to see to what degree it lowers THD slash improves the frequency response.
Then it's good that I posted it 😉.
"...improve sound at high output..."
Does 1W / ~ 105 dB count as "high output"?
We will be building a second one and improve the reinforcements on the first one. I am going to suggest adding some glass wool. If this doesn't improve THD, I might try measuring THD at a lower level to make sure it's not overloading the measurement chain (input reached about -4dB during the measurement sweep). It could take a while though; the 2nd 15ND930 has got a (very) stuck coil so it needs a recone 🙁
"...improve sound at high output..."
Does 1W / ~ 105 dB count as "high output"?
We will be building a second one and improve the reinforcements on the first one. I am going to suggest adding some glass wool. If this doesn't improve THD, I might try measuring THD at a lower level to make sure it's not overloading the measurement chain (input reached about -4dB during the measurement sweep). It could take a while though; the 2nd 15ND930 has got a (very) stuck coil so it needs a recone 🙁
Only potentially 😉
The unfavorable relation between distortion and output could mean that above a certain SPL it tips the threshold of lowering sound quality. Although they used a different driver, it was mentioned to me in relation to how high the upper crossover could be set, which was near the THD highest peak.