Exactly…that’s the plan. I have the 18Sound 10NMB520 which has an ultra low QTS for horn loading, 2-way using a 1kHz crossover point to a similar sized 1” horn.
If you want a deeper dive into this matter, I would recommend the simulation SW "AJHorn". There you can play with the driver position within the horn, dual drivers, internal absorbtion chambers etc. which might give you the possibility to get rid of the mid bass cancellation. It might be in German only. But that should be manageable ;-)
Maybe you could add a a quarter wave tuned resonnant chamber for the cancellation frequency. Some exhaust systems uses that to get rid of drone at a specific frequency.
Thanks for sharing, also your listeing impressions. FR looks rather rough. Interesting that 2.5m listening distance is near field for you :-) (here in the UK that's usually 1m)
Within 2.5m but normally closer. My brother now has these setup at the end of his bed, all tube front end. Even without room boundaries it sounds full.
Very nice design. I will definitely consider these for my next project. I much prefer the looks of wide baffles so that is reason enough for me, the gain in efficiency is a bonus. Isn't this really a transmission line tho? Anyways, I guess it can be defined as both depending on which parameters one let dominate.
I would say the difference is that I’m not relying on a damped line to attenuate the midrange. Also the mouth termination is an exponential flare into the room (as much as reasonably can be achieved) versus the conical flare rate of TL. I think TL relies on resonance similar to a port, but I’m trying to avoid resonance (first order reflections back down the line). But in practice they may be more similar than not…perhaps a TL is simply a horn in function.
If you line enough of big end the horn with soft surface absorption felt, and the interior of the first rear chamber area, you can absorb a great deal of the unwanted mid bass that causes cancelation. Been building these for decades. In essence, I want to think of it as a transmission line with acoustic gain in the line.... and to attenuate all frequencies above where the horn provides reinforcement as 1/4 wave. I'm currently running a single 16" Altec GPA 515-8LF in a large BLH... smaller than a Jensen Imperial and larger than ANY of the JBL scoops.. the bass impact essentially sums the driver area, plus mouth area.. resulting in body moving experience.. It produces more body slam than 4x 16" direct radiators per channel.
That was my experience with the 2095 BLH which I’ll be doing a video on shortly, which is a large 15” cabinet. The impact is the same as you describe, even with low power amplification. josephcrowe.com/blogs/news/15-back-loaded-horn-no-2095 Thanks for the feedback! The 2025 benefits from a pillow in the horn mouth. This is something I’ll try on the speakers in my video.
Wow many thanks Joseph, your vids/blogs are always very educational. Possible to use the same but deeper cabinet for 8 inch driver ? The horn lenght for said cut off frequency design should apply for different size driver too right or ???? Many thanks again
Oh I overlooked 1 point. Fundamentally it's gonna be a 3 way design right , for 2 way a huge horn would be needed in order to go down to 300hz unless you tweak the design to cut off at a higher frequency. Is my assumption correct ? Thank you again
Symphonia is still the best sounding speaker I've heard. Nice intro to the video, too! Would increasing Symphonia's horn mouth area be worthwhile? Interesting concept.
I’m glad to hear you appreciated the Symphonia as much as I did. The physical size of the Symphonia lends to me think that it’s mouth area is about right.
Any plans to do a video on the No.2095? Seems the Symphonia had some influence here too. Would be great to hear more of your thoughts on the No.2095.@@JosephCrowesDIYSpeakerBuilding
It would be interesting to hear how the similarly sized but higher sensitivity and flatter fq response curve Mark Audio CHP-90 would do in this spiral BLH
I tried the CHR-50 as well as a variety of other drivers. Mark Audio does not respond well at all to horn loading. It simply doesn’t have the motor strength (low QTS among other parameters). The Fostex FE83NV2 did incredibly well, same bass but didn’t go as loud as the FE108NS.
Interesting. I wonder what 10” full rangers would do in a BLH cabinet. (ie. Cube Audio F10) They are in Voigt pipe cab.s now-love ‘em, excellent bass.
Exactly…that’s the plan. I have the 18Sound 10NMB520 which has an ultra low QTS for horn loading, 2-way using a 1kHz crossover point to a similar sized 1” horn.
This was awesome. Thank you my Canadian brother. Hello from Victoria.
If you want a deeper dive into this matter, I would recommend the simulation SW "AJHorn".
There you can play with the driver position within the horn, dual drivers, internal absorbtion chambers etc. which might give you the possibility to get rid of the mid bass cancellation. It might be in German only. But that should be manageable ;-)
Thank you, I will check it out.
Maybe you could add a a quarter wave tuned resonnant chamber for the cancellation frequency. Some exhaust systems uses that to get rid of drone at a specific frequency.
back loaded horns and tl-s / voight pipes have unique sound - cheers for this project:)
Thanks for sharing, also your listeing impressions. FR looks rather rough. Interesting that 2.5m listening distance is near field for you :-) (here in the UK that's usually 1m)
Within 2.5m but normally closer. My brother now has these setup at the end of his bed, all tube front end. Even without room boundaries it sounds full.
Very nice design. I will definitely consider these for my next project. I much prefer the looks of wide baffles so that is reason enough for me, the gain in efficiency is a bonus. Isn't this really a transmission line tho? Anyways, I guess it can be defined as both depending on which parameters one let dominate.
I would say the difference is that I’m not relying on a damped line to attenuate the midrange. Also the mouth termination is an exponential flare into the room (as much as reasonably can be achieved) versus the conical flare rate of TL. I think TL relies on resonance similar to a port, but I’m trying to avoid resonance (first order reflections back down the line). But in practice they may be more similar than not…perhaps a TL is simply a horn in function.
If you line enough of big end the horn with soft surface absorption felt, and the interior of the first rear chamber area, you can absorb a great deal of the unwanted mid bass that causes cancelation. Been building these for decades. In essence, I want to think of it as a transmission line with acoustic gain in the line.... and to attenuate all frequencies above where the horn provides reinforcement as 1/4 wave. I'm currently running a single 16" Altec GPA 515-8LF in a large BLH... smaller than a Jensen Imperial and larger than ANY of the JBL scoops.. the bass impact essentially sums the driver area, plus mouth area.. resulting in body moving experience.. It produces more body slam than 4x 16" direct radiators per channel.
Interesting. Can you upload a video description of those?
That was my experience with the 2095 BLH which I’ll be doing a video on shortly, which is a large 15” cabinet. The impact is the same as you describe, even with low power amplification.
josephcrowe.com/blogs/news/15-back-loaded-horn-no-2095
Thanks for the feedback! The 2025 benefits from a pillow in the horn mouth. This is something I’ll try on the speakers in my video.
Wow many thanks Joseph, your vids/blogs are always very educational. Possible to use the same but deeper cabinet for 8 inch driver ? The horn lenght for said cut off frequency design should apply for different size driver too right or ???? Many thanks again
That’s correct. This was a design study plus proto build. I plan on developing this further as a 2-way with integrated wood horn.
Many thks for the reply Joseph, can't wait to see an 8 inch version
Oh I overlooked 1 point. Fundamentally it's gonna be a 3 way design right , for 2 way a huge horn would be needed in order to go down to 300hz unless you
tweak the design to cut off at a higher frequency. Is my assumption correct ?
Thank you again
Symphonia is still the best sounding speaker I've heard. Nice intro to the video, too! Would increasing Symphonia's horn mouth area be worthwhile? Interesting concept.
I’m glad to hear you appreciated the Symphonia as much as I did. The physical size of the Symphonia lends to me think that it’s mouth area is about right.
Any plans to do a video on the No.2095? Seems the Symphonia had some influence here too. Would be great to hear more of your thoughts on the No.2095.@@JosephCrowesDIYSpeakerBuilding
It would be interesting to hear how the similarly sized but higher sensitivity and flatter fq response curve Mark Audio CHP-90 would do in this spiral BLH
I tried the CHR-50 as well as a variety of other drivers. Mark Audio does not respond well at all to horn loading. It simply doesn’t have the motor strength (low QTS among other parameters). The Fostex FE83NV2 did incredibly well, same bass but didn’t go as loud as the FE108NS.
reminds me of VTL design.