Here is cool speaker that I helped member Sirvalence with the design and he built them himself. He was too busy to post this but I thought folks might find this interesting.
A Beyma TPL-150 AMT tweeter is used in a straight wall expansion horn with some midbass injection provided by an SB Acoustics SB23NRXS45-8 woofer. The horn is about 52.5cm wide x 34cm tall at the mouth and 22cm deep (external dims) with a rectangular throat 25mm wide x 126mm tall. The angles are approximately 80 deg H x 30 deg V. The woofer fires through two 100mm x 23mm hotdog shaped ports located as close as possible to the throat such that the end of the port is about 35mm from the throat. The woofer is upfiring through the two ports and the backside rests on a large 30cm dia x 1m cardboard tubes which serves as both a stand and the bass chamber. The whole thing is active with a DSP crossover at about 1350Hz but sometimes plays them crossed low like a FAST at 550Hz. Yes, it is amazing that the TPL-150 can go that low. I think he uses basic TPA3116 Class D amps and runs these as a quadrophonic system.
Here was the foamcore pathfinder:
Then he made them in 18mm BB plywood.
Here are the four horns:
Side View Detail:
Rear View AMT mounting detail:
Woofer mounting plate detail:
Adpater plate detail:
He says they sound great. Still playing with the DSP crossover settings and taking measurements to refine. We will try develop a passive XO for this at some point.
A Beyma TPL-150 AMT tweeter is used in a straight wall expansion horn with some midbass injection provided by an SB Acoustics SB23NRXS45-8 woofer. The horn is about 52.5cm wide x 34cm tall at the mouth and 22cm deep (external dims) with a rectangular throat 25mm wide x 126mm tall. The angles are approximately 80 deg H x 30 deg V. The woofer fires through two 100mm x 23mm hotdog shaped ports located as close as possible to the throat such that the end of the port is about 35mm from the throat. The woofer is upfiring through the two ports and the backside rests on a large 30cm dia x 1m cardboard tubes which serves as both a stand and the bass chamber. The whole thing is active with a DSP crossover at about 1350Hz but sometimes plays them crossed low like a FAST at 550Hz. Yes, it is amazing that the TPL-150 can go that low. I think he uses basic TPA3116 Class D amps and runs these as a quadrophonic system.
Here was the foamcore pathfinder:
Then he made them in 18mm BB plywood.
Here are the four horns:
Side View Detail:
Rear View AMT mounting detail:
Woofer mounting plate detail:
Adpater plate detail:
He says they sound great. Still playing with the DSP crossover settings and taking measurements to refine. We will try develop a passive XO for this at some point.
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I'm playing about with a few synergy type horn ideas ATM, mainly using 3" drivers at the mouth, inspired by X and Bushmeisters off the shelf horn designed but using modified conical horns.
They showed better HD capabilities than many cd so I think it's worth pursuing. Though not if you're optimizing for efficiency.
Anyhow I've been using tpl150h as the top of my 4 way mainly horn system and was recommended trying the Beyma in a synergy. My crossover points have been 100-600-2500, but I'm trying out some sealed 15" mid/bass boxes instead of my midbass horns which makes a TPL MEH with 2.5-4" mid drivers adding ~300-1800 a tempting solution. They could sit above my 15s. Though perhaps the 100-300hz region would mess up the point source effect?
Worth knocking up a test cab up I reckon.
They showed better HD capabilities than many cd so I think it's worth pursuing. Though not if you're optimizing for efficiency.
Anyhow I've been using tpl150h as the top of my 4 way mainly horn system and was recommended trying the Beyma in a synergy. My crossover points have been 100-600-2500, but I'm trying out some sealed 15" mid/bass boxes instead of my midbass horns which makes a TPL MEH with 2.5-4" mid drivers adding ~300-1800 a tempting solution. They could sit above my 15s. Though perhaps the 100-300hz region would mess up the point source effect?
Worth knocking up a test cab up I reckon.
@xrk971 thanks for posting this! Once again, a lot of food for thought.
I have TPL-150H open in the back (dipole) and crossing them at 1.3kHz, so I would imagine with these larger horns your friend should be able to xo lower, likely at 1.1, maybe at 1kHz. BTW, it would be worth for him to experiment removing the factory back plastic chamber in the TPL and replacing with a larger chamber, removing the factory felt, and adding some loose padding in the chamber. Made a significant difference for me!
Where can I read about the midrange design considerations? Instead of the SB Acoustics SB23NRXS45-8 he uses I have a B&C 8PE21 and wonder if it would be a good fit and what size chamber I would need for them.
I still have your XSD woofer section in my mind. Do you think these might synergize? Right now my treble, midrange, midbass are OB and I'm considering options starting with the midbass. Your XSD woofer section is a top contender. Getting AE LO15 in OB is another. And sealed midbass is the 3rd
I have TPL-150H open in the back (dipole) and crossing them at 1.3kHz, so I would imagine with these larger horns your friend should be able to xo lower, likely at 1.1, maybe at 1kHz. BTW, it would be worth for him to experiment removing the factory back plastic chamber in the TPL and replacing with a larger chamber, removing the factory felt, and adding some loose padding in the chamber. Made a significant difference for me!
Where can I read about the midrange design considerations? Instead of the SB Acoustics SB23NRXS45-8 he uses I have a B&C 8PE21 and wonder if it would be a good fit and what size chamber I would need for them.
I still have your XSD woofer section in my mind. Do you think these might synergize? Right now my treble, midrange, midbass are OB and I'm considering options starting with the midbass. Your XSD woofer section is a top contender. Getting AE LO15 in OB is another. And sealed midbass is the 3rd
Hi Lewinski,
Glad you like this thread. Good tips on modifying back chamber. I made a Dagger rear chamber for my Heil AMT and it sounded great.
Regarding midrange, a pro mid like your B&C is fine. I used B&C 6MDN44 on mine. You need to make sure the bandwidth is wide enough to overlap.
The XSD bass woofer array would indeed be a perfect match. The 92dB sensitivity and dynamics with OB bass that is mostly free from room modes. That would indeed be a potent combo.
Glad you like this thread. Good tips on modifying back chamber. I made a Dagger rear chamber for my Heil AMT and it sounded great.
Regarding midrange, a pro mid like your B&C is fine. I used B&C 6MDN44 on mine. You need to make sure the bandwidth is wide enough to overlap.
The XSD bass woofer array would indeed be a perfect match. The 92dB sensitivity and dynamics with OB bass that is mostly free from room modes. That would indeed be a potent combo.
From my own anecdotal experience in my own listening room - the SLOB bass doesn’t vary when I walk 4 feet to left and don’t hear any dropout in the bass. So I beg to differ on this. It’s very noticeable on monopole bass. Maybe it’s not that fewer modes are excited but whatever is happening, bass is more uniform throughout the room.