I kind of like this TH. I tried to make an isobaric 6th order band pass about 25 years ago and it just sounded like crap. I don't know if they all sound like a big boom box, or if I just got the ports all wrong. I kind of like having the driver diaphragm exposed like a RLH or TH where it is very visible. I am trying to make some sub 100Hz boxes for a 4 way speaker mostly for music and don't want to turn the sound into doof doof.
I think that is a typo in the book where they have the BR and isobaric BR listed as a 4th order. The BP on the following page are 4th order.
I used a cylindrical tube rather than a flared horn to highlight the combing effect.
The combing effect is nowhere near as pronounced if a realistic horn flare is used instead. Try it for yourself.
To further reduce the effect a chamber can be added between the rear of the driver and the horn throat to act as an acoustic low pass filter.
if of help, MJ King discussed the function and simulation of coupling chamber with the speaker at different positions in a BLH. Back_Horn.pdf.
A number of simulations of the separate speaker and mouth output as well as the combined response are done at "far field" while some are at 1m. There is an explanation but couldn't pinpoint it just now.
A number of simulations of the separate speaker and mouth output as well as the combined response are done at "far field" while some are at 1m. There is an explanation but couldn't pinpoint it just now.
Hi,
playing along with Hornresp I came along a desktop labyrinth TL. I have found what I think is a nice alignment. I hope on just ligning it with fool felt. But I need quite a lot of damping to kill the upper harmonics in the region of 450-600Hz.
The box will be 3 times folded, so I dont know they might be eaten up by the folds? I am unsure on how important they still are.
I attached 3 frequency graphs with different stuffing applied. I assume when I set a filling about 50 I might get along with lining with wool felt?
playing along with Hornresp I came along a desktop labyrinth TL. I have found what I think is a nice alignment. I hope on just ligning it with fool felt. But I need quite a lot of damping to kill the upper harmonics in the region of 450-600Hz.
The box will be 3 times folded, so I dont know they might be eaten up by the folds? I am unsure on how important they still are.
I attached 3 frequency graphs with different stuffing applied. I assume when I set a filling about 50 I might get along with lining with wool felt?
I think the folds will kill the upper harmonics.
If you read some of infamous tapped horn threads, some of the designers mention running the enclosure without a low pass filter and still sounding good to their ears. That's why I don't sweat anything after 100hz. Once you put a realistic low pass filter on the enclosure, all that harmonic crap is NULL AND VOID. And, you still have the option to add stuffing. See the 4 $29 JBL 12's Devastator thread on avsforum.com. They have before and after distortion measurements with 2 pillows in the enclosure.
If you read some of infamous tapped horn threads, some of the designers mention running the enclosure without a low pass filter and still sounding good to their ears. That's why I don't sweat anything after 100hz. Once you put a realistic low pass filter on the enclosure, all that harmonic crap is NULL AND VOID. And, you still have the option to add stuffing. See the 4 $29 JBL 12's Devastator thread on avsforum.com. They have before and after distortion measurements with 2 pillows in the enclosure.
For what. I'm not listening to the enclosure that high in frequency, especially with the 12dB slope low pass filter @ 80hz from the AVR and 12dB slope low pass filter @ 200hz from the subwoofer amplifier. The T-TQWT enclosure has done me just fine since 2012 with the original driver. I got 15" PA 2 ways handling 80hz on up.
Thank you David.
I added a chamber in the input parameters window and it does a very good job at reducing the comb filtering as well as improving low end response.
The chamber parameters in Hornresp (Vrc-Lrc) are for a closed chamber, while in BLH it is an open coupling chamber so I wonder if the simulation of the chamber in hornresp is accurate enough also for a BLH, or if the coupling chamber would be better calculated separately instead.
Possibly also according to MJ King's document linked by @woodo where the coupling chamber is discussed also in relation to the position of the driver and throat within the chamber. Not sure if the difference is relevant (if any).