Peter, may be best to change into Grand Slamm clone
Peter,
How about spending a little time turning this speaker into a true Grand Slamm clone? You have very expensive hi-end drivers that can sound amaziing if matched to the correct box design and crossover. You would need different woofers with higher Qts and Xmax for a good dipole, and need to use a steeper crossover on the R1 anyway.
I'm sure you have considered...
1) crossover the R1 with the 4th or 6th order passive Xover at the Orca or Zalytron websites.
2) Seal the MTM in the correct volume sealed box, well stuffed and braced . Steep LR4 or LR6 crossover to R1 ribbon, LR4 crossover to Focal 12" and 15" which form 1.5 way bass.
3) Seal the FOcal 12" in the correct sealed box, well stuffed and braced. Crossover the 12" and 15" as a 1.5 way. This will maintain the WMTMW radiation pattern. use electric LR4 to mid-tweet.
4) put the Focal 15" in a ported box, and adjust the crossover to accomplish the baffle step and to cover the bottom bass. Vent this box near the bottom front for the best and most even floor gain boost.
Although the passive components will not be cheap, bi-amping will save the cost of large bass inductors. These are very efficient speakers, and any of your DIY amps that can drive the 3 ohm load should have no power problems.
The speakers look great, and there is no reason they could not approach the Grand Slamm sonics
Peter,
How about spending a little time turning this speaker into a true Grand Slamm clone? You have very expensive hi-end drivers that can sound amaziing if matched to the correct box design and crossover. You would need different woofers with higher Qts and Xmax for a good dipole, and need to use a steeper crossover on the R1 anyway.
I'm sure you have considered...
1) crossover the R1 with the 4th or 6th order passive Xover at the Orca or Zalytron websites.
2) Seal the MTM in the correct volume sealed box, well stuffed and braced . Steep LR4 or LR6 crossover to R1 ribbon, LR4 crossover to Focal 12" and 15" which form 1.5 way bass.
3) Seal the FOcal 12" in the correct sealed box, well stuffed and braced. Crossover the 12" and 15" as a 1.5 way. This will maintain the WMTMW radiation pattern. use electric LR4 to mid-tweet.
4) put the Focal 15" in a ported box, and adjust the crossover to accomplish the baffle step and to cover the bottom bass. Vent this box near the bottom front for the best and most even floor gain boost.
Although the passive components will not be cheap, bi-amping will save the cost of large bass inductors. These are very efficient speakers, and any of your DIY amps that can drive the 3 ohm load should have no power problems.
The speakers look great, and there is no reason they could not approach the Grand Slamm sonics
Well, I never complained about bass from those dipoles. This is actually what they do the best. I don't need 500W out of them, and what I get right now is fine.
The problem is with mid/high interface. Originally, I had third order filter on Raven and second order low pass on mids. It was fine, but nothing comparing to what I get with running mids without crossover and first order on tweeter. But then, the response is not good.
Using 4th and 6th order filters is out of question in my book. It is not acceptable. Sorry 😉
The problem is with mid/high interface. Originally, I had third order filter on Raven and second order low pass on mids. It was fine, but nothing comparing to what I get with running mids without crossover and first order on tweeter. But then, the response is not good.
Using 4th and 6th order filters is out of question in my book. It is not acceptable. Sorry 😉
Closed box Grand Slam
Pete,
Here is what I was thinking.......
Joe D'Appolito recommended either a 1st or 3rd order crossover in his MTM publications to get the optimal horizontal lobe angles. Other authors have experimented and mathematically shown that the LR4 can maintain an acceptable center lobe angle if the speakers are physically very close together, and LR4 can also deliver better transient response.
To avoid beaming effects at just 15 degrees off-axis, a 5" cone speaker should be crossed by 3,000 Hz. Orca recommends a 6th order crossover at 2Khz for full power, but limiting the SPL to 105db would allow a 2nd or 3rd order at 2.5-3Khz, with the 3rd order meeting D'Appolito's lobing pattern recommendation. A LR4 at 3KHz would allow >110db SPL transients. Many designers try to avoid crossovers between 1K-3KHz due to ear sensitivities to changes in this range. MTM crossover seems best at 3Khz. 3rd order Butterworth would give the best lobe tilt. LR4 would generate a less ideal center lobe angle but better transient response, plus allow higher power. A sealed MTM box alignment will provide the best transients, and allow the easiest crossover to the woofers.
The ideal M-W crossover is 80-100Hz, as this covers the male bass voice. Most 5” drivers in a sealed box can reach no farther than 300Hz, and 300-3,000 is also better for midrange intermodulation distortion and Xmax even with two mids. Mid IMD is 7% at 110db SPL, 2.5mm Xmax for each 5”. Mid IMD is 0.7% for 90db SPL, 0.2mm Xmax. The ~300Hz crossover to the 12” and 15” can again be 3rd order to maintain a common lobbing pattern (less important at lower frequencies) with the MTM, or LR4 if the MTM is LR4 to improve midrange max SPL, and deliver better transient response. Some designers like to set the M-W crossover at the baffle step frequency, as the 2-pi to 4-pi transistion can be accomplished by just increasing the gain on the woofer electronic crossover. An 16" wide baffle would be a 304 Hz baffle step ( 380/W' ), and a reasonable M-W crossover point. A sealed box for the 12” would match the sealed MTM transient response. Since the 15” has a low Qts, Fs, and a modest Xmax, a ported 15” box might be considered to extend the bass one octave, without special equalization to the 12" vs. 15".
Pete,
Here is what I was thinking.......
Joe D'Appolito recommended either a 1st or 3rd order crossover in his MTM publications to get the optimal horizontal lobe angles. Other authors have experimented and mathematically shown that the LR4 can maintain an acceptable center lobe angle if the speakers are physically very close together, and LR4 can also deliver better transient response.
To avoid beaming effects at just 15 degrees off-axis, a 5" cone speaker should be crossed by 3,000 Hz. Orca recommends a 6th order crossover at 2Khz for full power, but limiting the SPL to 105db would allow a 2nd or 3rd order at 2.5-3Khz, with the 3rd order meeting D'Appolito's lobing pattern recommendation. A LR4 at 3KHz would allow >110db SPL transients. Many designers try to avoid crossovers between 1K-3KHz due to ear sensitivities to changes in this range. MTM crossover seems best at 3Khz. 3rd order Butterworth would give the best lobe tilt. LR4 would generate a less ideal center lobe angle but better transient response, plus allow higher power. A sealed MTM box alignment will provide the best transients, and allow the easiest crossover to the woofers.
The ideal M-W crossover is 80-100Hz, as this covers the male bass voice. Most 5” drivers in a sealed box can reach no farther than 300Hz, and 300-3,000 is also better for midrange intermodulation distortion and Xmax even with two mids. Mid IMD is 7% at 110db SPL, 2.5mm Xmax for each 5”. Mid IMD is 0.7% for 90db SPL, 0.2mm Xmax. The ~300Hz crossover to the 12” and 15” can again be 3rd order to maintain a common lobbing pattern (less important at lower frequencies) with the MTM, or LR4 if the MTM is LR4 to improve midrange max SPL, and deliver better transient response. Some designers like to set the M-W crossover at the baffle step frequency, as the 2-pi to 4-pi transistion can be accomplished by just increasing the gain on the woofer electronic crossover. An 16" wide baffle would be a 304 Hz baffle step ( 380/W' ), and a reasonable M-W crossover point. A sealed box for the 12” would match the sealed MTM transient response. Since the 15” has a low Qts, Fs, and a modest Xmax, a ported 15” box might be considered to extend the bass one octave, without special equalization to the 12" vs. 15".
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