Hey!
So I've built these speakers:
The build and more details are available in this thread. But basically, it is a synergy type of speaker with 18Sound XT1464 SOTA waveguide, the design of which was originally implemented by Bushmeister and XRK. I mostly replicated it with pro mids (Beyma 8G40) and pro CD - Faital HF146.
Unfortunately, when i try to integrate these two speakers with an old Velodyne sub (a vented 12" rated at 350W, IIRC), i get a strong dip at about 100Hz. Even when i try to cross at 100Hz, even with sub crossed with 2nd LR filter. The problem in my opinion is not in the room, it is more in the ability of two Beyma 8G40 to play that low.
Here is how it models:
Unfortunately, i do not have a measurement at my hands, but it measures approximately the same. I added some boost at the DSP so that the measurement resembles LR 4th order slope at 100Hz, but it resembles a 36 or even 48db slope more.
One option is to vent the speaker and tune the vent to about 60Hz:
This way i fix the dip at the crossover frequency and can use the same sub.
Another option is to add a couple of 15" or even 18" subs in the corners in vented boxes tuned to a frequency that makes an F3 about 30-35" and then cross to the rest of the system to about 120Hz. This way i get rid of the velodyne and get PA style subs that get into the lower bass region with the dynamics and big sound.
Here are a few options of how it may look:
I've modelled a couple of drivers, namely Faital 15PR400 and Beyma 18LX60V2.
For those two drivers venting is not enough, i need to apply a boost of 4-6db in order to extend low end to 35Hz.
Here is how this driver maxes out with 6db boost applied at 35Hz and xmax at 9mm in 0.5Pi configuration at 250W into 8Ohms:
And here is Faital 15PR400 in the same kind of enclosure (90 liters) and about the same boost maxed out with 6mm xmax:
- Do you think any of these two drivers will fit the bill?
- Am i going to have problems with room modes due to subs being located in the corners (an audiophile dogma?)?
- Any problems integrating with hanging synergy speakers at about 120Hz?
So I've built these speakers:
The build and more details are available in this thread. But basically, it is a synergy type of speaker with 18Sound XT1464 SOTA waveguide, the design of which was originally implemented by Bushmeister and XRK. I mostly replicated it with pro mids (Beyma 8G40) and pro CD - Faital HF146.
Unfortunately, when i try to integrate these two speakers with an old Velodyne sub (a vented 12" rated at 350W, IIRC), i get a strong dip at about 100Hz. Even when i try to cross at 100Hz, even with sub crossed with 2nd LR filter. The problem in my opinion is not in the room, it is more in the ability of two Beyma 8G40 to play that low.
Here is how it models:
Unfortunately, i do not have a measurement at my hands, but it measures approximately the same. I added some boost at the DSP so that the measurement resembles LR 4th order slope at 100Hz, but it resembles a 36 or even 48db slope more.
One option is to vent the speaker and tune the vent to about 60Hz:
This way i fix the dip at the crossover frequency and can use the same sub.
Another option is to add a couple of 15" or even 18" subs in the corners in vented boxes tuned to a frequency that makes an F3 about 30-35" and then cross to the rest of the system to about 120Hz. This way i get rid of the velodyne and get PA style subs that get into the lower bass region with the dynamics and big sound.
Here are a few options of how it may look:
I've modelled a couple of drivers, namely Faital 15PR400 and Beyma 18LX60V2.
For those two drivers venting is not enough, i need to apply a boost of 4-6db in order to extend low end to 35Hz.
Here is how this driver maxes out with 6db boost applied at 35Hz and xmax at 9mm in 0.5Pi configuration at 250W into 8Ohms:
And here is Faital 15PR400 in the same kind of enclosure (90 liters) and about the same boost maxed out with 6mm xmax:
- Do you think any of these two drivers will fit the bill?
- Am i going to have problems with room modes due to subs being located in the corners (an audiophile dogma?)?
- Any problems integrating with hanging synergy speakers at about 120Hz?
Attachments
With EQ subs in corners may be a close to optimal position (see Harmen presentation on sub positioning).
If you don't need the maximum output of the 18" subs then I would tune them lower than 35 Hz and EQ them flat. Just beware the pipe mode of very long ports.
120Hz crossover is what I use and is fine, I think perhaps people who say that they can localize the subs at this frequency are using an electrical 120Hz crossover but acoustically crossing much higher.
The two drivers you have selected have less xmax than I would look for in a sub driver, I'm guessing your based in EU from your choices and are looking for a relatively low cost driver. I would look at something like the B&C 15TBX100 or 18TBX100. Beware that Faital pro uses a different xmax formula to other manufacturers thats more optimistic.
If you don't need the maximum output of the 18" subs then I would tune them lower than 35 Hz and EQ them flat. Just beware the pipe mode of very long ports.
120Hz crossover is what I use and is fine, I think perhaps people who say that they can localize the subs at this frequency are using an electrical 120Hz crossover but acoustically crossing much higher.
The two drivers you have selected have less xmax than I would look for in a sub driver, I'm guessing your based in EU from your choices and are looking for a relatively low cost driver. I would look at something like the B&C 15TBX100 or 18TBX100. Beware that Faital pro uses a different xmax formula to other manufacturers thats more optimistic.
No, i am only looking at what's possible at about 30-35Hz at maximum xmax/power. Beyma's 18" is 4dBs louder than an 15" driver at this frequency (124 vs 128dB). I think that will be more than plenty for me. Hopefully, corner loading will lower FM distortion.
Do you mean port velocity by pipe modes?
When you are EQing for acoustic crossover, do you use a 1 meter measurements or listening position?
Yeah, very limited by the the choice of the drivers. These 15" Beymas are optimal in terms of the price.
Didn't know that about Faital's xmax data. Thanks!
I doubt you will use the full output of 2*18" drivers most domestic rooms develop annoying buzzes and rattles if you get anywhere near 128dB.
If the port is long enough you will start to see a notch in the response caused in the pass band.
Listening position vector average over multiple locations or spatial average using periodic pink noise and infinite persistence on RTA.
Pretty much, I use 4*15" (8 drivers isobaric see sig) tuned to 28Hz. At 'full output' that's enough to cause a noise disturbance to anyone within a few hundred meters. I've left all night parties before when there still playing (in industrial areas) and been able to hear the bass many streets away. However 15PR400 is more of a midbass so I would (if those are your only choices) choose the 18".
yep the port will be tuned lower than expected. Also as there is no flare on your port you will have to keep port air velocity lower than a flared port to avoid port losses and and noises.
SM-115/N is more of a high performance midbass for a two/three way speaker but it will work as a sub, after all it has 7.25mm xmax and a 3" voice coil. Might need some EQ to be flat down to your 35Hz tune.
SM-115/N is more of a high performance midbass for a two/three way speaker but it will work as a sub, after all it has 7.25mm xmax and a 3" voice coil. Might need some EQ to be flat down to your 35Hz tune.
Thanks, man!
Any rule on how far from the wall should vent be located? Does bending a port sound like a good solution?
Yeah, i aim for no more than 17m/s or air velocity at maximum SPL.
Well, let's use pipes then:
WinISD and Hornresp give slightly different resonant frequencies for two tubes 100mm dia and 400mm length. WinISD estimates at tuning at ~30Hz while Hornresp at ~27.
About 75W may be fed into the driver before it reaches XMax with 9db boost applied at 30Hz Q=1,2 (eights space sim):
WinISD and Hornresp give slightly different resonant frequencies for two tubes 100mm dia and 400mm length. WinISD estimates at tuning at ~30Hz while Hornresp at ~27.
About 75W may be fed into the driver before it reaches XMax with 9db boost applied at 30Hz Q=1,2 (eights space sim):
Attachments
Whats the air velocity for this port? you can see this in Hornresp by selecting just the port output and then the option to see the particle velocity at input and output of the port becomes available.
If you build the first sub with a panel screwed down before you glue you can adjust the length of your pipe ports to get exactly the tuning you want.
If you build the first sub with a panel screwed down before you glue you can adjust the length of your pipe ports to get exactly the tuning you want.
Found another driver (although, used) - 18Sound 15LW1401. I use this driver in an open baffle setup already.
This is how it compares with Beyma SM115 in an 8th space:
Although it has higher resonant frequency (42Hz vs 35Hz), it has higher xmax. Some other parameters might be at play as well, since response is not falling as dramatically as with Beyma.
This is how it compares with Beyma SM115 in an 8th space:
Although it has higher resonant frequency (42Hz vs 35Hz), it has higher xmax. Some other parameters might be at play as well, since response is not falling as dramatically as with Beyma.
