Ok, I understand. For a 100-400hz passband, this means a horn having reasonably performance in the 50-800 hz area. Quite a long horn: will not the length have negative influence on the upper end performance? If so, I will prioritize upper range SQ, as I have 4 18" to take over below themidbass horn (and these have no problem reaching 150 hz; AE Td18h+)
Best regards
Gisle
Audiodidakt,
It would help if you state your ultimate speaker goal, is this going to be a full horn system ? How big is your room, budget, speaker system size limitations ? You need to listen to most horn systems at 12+ ft. back.
About 4 yrs. ago, I was in the same situation as you. I wanted the most performance possible from a mid bass horn design that would fit in my space--it had to fit through a 34.5" door opening. I read all that I could and paid a visit to Dr. Bruce Edgar since I was at the Newport audio show. Dr. Bruce kindly gave me all the info I needed to make a pair mid bass horns using a pair of Altec 515b's per horn. The horn had a finished mouth of 34" x 45" and was about 47" deep. The throats were about 10.5" square per driver and had a carefully made wedge about 18" long placed between the drivers instead of having a flat area between the driver throats. This horn measures very flat between 58 hz and 450 hz in my room and sounds great --- and that is what matters to me. Is it perfect, probably not but I have yet to hear more power, snap, live feeling from music in the MANY audio shows I have been to since year 2000 after listening to almost all the mega-buck speakers.
You will find several mid bass driver options as you search the web. Your JBL driver will work fine. Dr. Bruce favored EV 15b/l drivers. Cessaro acoustics uses a Supervox 11" driver for their mid bass horn and other people use a limited production 8" driver from Faital. Beyma has some nice 12" drivers that would also work well. There are also some exotic ( field coil ) drivers I did not mention that would also work. You can also look at Roamy the Cat's site ( Good Sound Club ) for lots of info on horns. So, pick your poison and build the best you can !!!
For home audiophile use, I would keep any 18" woofer well away from the mid range even though many can sound good past 500hz. Let your mid bass horn cover the critical 80hz to 500hz range. Good luck.
It would help if you state your ultimate speaker goal, is this going to be a full horn system ? How big is your room, budget, speaker system size limitations ? You need to listen to most horn systems at 12+ ft. back.
About 4 yrs. ago, I was in the same situation as you. I wanted the most performance possible from a mid bass horn design that would fit in my space--it had to fit through a 34.5" door opening. I read all that I could and paid a visit to Dr. Bruce Edgar since I was at the Newport audio show. Dr. Bruce kindly gave me all the info I needed to make a pair mid bass horns using a pair of Altec 515b's per horn. The horn had a finished mouth of 34" x 45" and was about 47" deep. The throats were about 10.5" square per driver and had a carefully made wedge about 18" long placed between the drivers instead of having a flat area between the driver throats. This horn measures very flat between 58 hz and 450 hz in my room and sounds great --- and that is what matters to me. Is it perfect, probably not but I have yet to hear more power, snap, live feeling from music in the MANY audio shows I have been to since year 2000 after listening to almost all the mega-buck speakers.
You will find several mid bass driver options as you search the web. Your JBL driver will work fine. Dr. Bruce favored EV 15b/l drivers. Cessaro acoustics uses a Supervox 11" driver for their mid bass horn and other people use a limited production 8" driver from Faital. Beyma has some nice 12" drivers that would also work well. There are also some exotic ( field coil ) drivers I did not mention that would also work. You can also look at Roamy the Cat's site ( Good Sound Club ) for lots of info on horns. So, pick your poison and build the best you can !!!
For home audiophile use, I would keep any 18" woofer well away from the mid range even though many can sound good past 500hz. Let your mid bass horn cover the critical 80hz to 500hz range. Good luck.
I am overwhelmed by all the help I receive here, thank you very much.
Let me explain my future system:
Room: currently my house is too small for my and my family, so a move will happen some time in the future. However, I will make a system with plenty over-capasity in my current room, to learn and test. The room is 3.15 x 5.8 meters and have a saddle roof, i.e. I am in the top floor. This is a horrible room for audio, but is what I've got.
System:
Xo - minidsp 4x10hd (which I might compliment with a minidsp 2x4hd for sub-channels if these two work together - have asked for guidance at minidsp.com-forum)
Tweeter: planned to be Fostex t90a, working from 8-10 000 hz and upwards. I also have Mundorf hpl150h and Mundorf amt2530 to try out if the horn-way does not work
Midrange: Radian 475 bebp, which I have a few horn I can test for: Jmlc 800 (special made), Jmlc 2000, faithal lth102 and jbl 2380a. Planned fr area to cover: 2000 to 8-10 000 hz.
Lower midrange: jmlc 200t with BMS 4590. I also have an jbl 2446 to test out in the horn but the measurement at horns-diy.pl are with the bms driver and they measure very good.
The horn will play in the area 350-400 to 2000-3000 hz with the bms. The jbl cannot be take below 500. I also have a jbl2360a horn to test, if I am not satisfied with the jmlc.
For midbass-horn duty I have 4 x jbl 2220, which I want to cover the area from 4-500 and downwards as far as possible within physical restraints (size) and as long as do not have a negative influence on the upper end.
More about the horn:
As the room is not very wide (3.15 meters), I will position the horn next to sidewall, i.e. a 4pi environment. The mouth of the horn will follow the floor and sidewall inthe last stages of the horn (i.e. be straight), meaning the the upper side and the other vertical side will do all the expansion of the horn. I am a bit worried for what effect this have on dispersion characteristics, but as for loading/impedans I presume it will be more or less equal to a horn with 4 expanding sides.
Maximum length of the horn is around 90-100 cm. I presume 90-100 is as low as it will go, but that is fine.
Maximum mouth size is 120x80 cm. I go for best possible upper-frequency, thus (!) plan on using only one driver per side but then with a double mouth area (120x80x1 in stead of 120x40x2)
Compression: need to be decided with hornresp, but I presume somewhere around 2:1. I am also planing to use a phase plug.
The transition from driver-throat-horn will be made smooth from round to square.
Listening distance from horn's mouth: apx 2.4 meters
Bass duty will be made by in-wall bass drivers.
I do have rpg bad panels and also ecophon to take care of upper range acoustics, but not in the bass area (might be bought later)
Best regards
Gisle
Let me explain my future system:
Room: currently my house is too small for my and my family, so a move will happen some time in the future. However, I will make a system with plenty over-capasity in my current room, to learn and test. The room is 3.15 x 5.8 meters and have a saddle roof, i.e. I am in the top floor. This is a horrible room for audio, but is what I've got.
System:
Xo - minidsp 4x10hd (which I might compliment with a minidsp 2x4hd for sub-channels if these two work together - have asked for guidance at minidsp.com-forum)
Tweeter: planned to be Fostex t90a, working from 8-10 000 hz and upwards. I also have Mundorf hpl150h and Mundorf amt2530 to try out if the horn-way does not work
Midrange: Radian 475 bebp, which I have a few horn I can test for: Jmlc 800 (special made), Jmlc 2000, faithal lth102 and jbl 2380a. Planned fr area to cover: 2000 to 8-10 000 hz.
Lower midrange: jmlc 200t with BMS 4590. I also have an jbl 2446 to test out in the horn but the measurement at horns-diy.pl are with the bms driver and they measure very good.
The horn will play in the area 350-400 to 2000-3000 hz with the bms. The jbl cannot be take below 500. I also have a jbl2360a horn to test, if I am not satisfied with the jmlc.
For midbass-horn duty I have 4 x jbl 2220, which I want to cover the area from 4-500 and downwards as far as possible within physical restraints (size) and as long as do not have a negative influence on the upper end.
More about the horn:
As the room is not very wide (3.15 meters), I will position the horn next to sidewall, i.e. a 4pi environment. The mouth of the horn will follow the floor and sidewall inthe last stages of the horn (i.e. be straight), meaning the the upper side and the other vertical side will do all the expansion of the horn. I am a bit worried for what effect this have on dispersion characteristics, but as for loading/impedans I presume it will be more or less equal to a horn with 4 expanding sides.
Maximum length of the horn is around 90-100 cm. I presume 90-100 is as low as it will go, but that is fine.
Maximum mouth size is 120x80 cm. I go for best possible upper-frequency, thus (!) plan on using only one driver per side but then with a double mouth area (120x80x1 in stead of 120x40x2)
Compression: need to be decided with hornresp, but I presume somewhere around 2:1. I am also planing to use a phase plug.
The transition from driver-throat-horn will be made smooth from round to square.
Listening distance from horn's mouth: apx 2.4 meters
Bass duty will be made by in-wall bass drivers.
I do have rpg bad panels and also ecophon to take care of upper range acoustics, but not in the bass area (might be bought later)
Best regards
Gisle
It is important to understand what hornresp is best at doing.
If the ripples you are seeing appear to be the same effect across the band it might be a literal translation of mouth effects. The ripple might not be so pronounced in an actual horn.
Hornresp models the driver as a flat source. Throat effects that are due to cone geometry and come down to waveguide theory, are something that is under your control.
The rear chamber resonances are a good guideline but actual rear chamber/basket geometry is likely to be more complex, especially at higher frequencies.
If the ripples you are seeing appear to be the same effect across the band it might be a literal translation of mouth effects. The ripple might not be so pronounced in an actual horn.
Hornresp models the driver as a flat source. Throat effects that are due to cone geometry and come down to waveguide theory, are something that is under your control.
The rear chamber resonances are a good guideline but actual rear chamber/basket geometry is likely to be more complex, especially at higher frequencies.
overly complex
Greetings and I mean this in the kindest possible way: this planned 5-way is much too complex and over-sized to fit your room. As much as i like a 4 -way, this too, might be over the top, especially considering a listening distance of approx 8 feet. A question for you to ponder: can you get it done in a 3 way ?
Greetings and I mean this in the kindest possible way: this planned 5-way is much too complex and over-sized to fit your room. As much as i like a 4 -way, this too, might be over the top, especially considering a listening distance of approx 8 feet. A question for you to ponder: can you get it done in a 3 way ?
58-450 !!!!
Sir, if you have achieved 58-450 Hz from a mid-bass horn design from Bruce Edgar, you have achieved what many, many have been seeking. Congrats !!
Sir, if you have achieved 58-450 Hz from a mid-bass horn design from Bruce Edgar, you have achieved what many, many have been seeking. Congrats !!
Dispersion below 500Hz may be less of a concern in the specific sense of each direction than say, the treble, and the overall dispersion ie power vs pressure might be worth a though, wanting to be smooth and to blend. Really though it may be fairly wide here anyway.
The extra expansion you have shown seems neat and smooth. It should probably come down to whether a given frequency will be using all of the horn or just the early part, and whether directivity is right or is even an issue at a given frequency or whether loading would be your chosen priority.
Using the floor and side wall in the bass is something Jean-Michel LeCleach advocated as an option in his thread, as he explains there.
If you want to model in hornresp you might use your actual total expansion with 1 pi loading for floor and 1 wall axial quartering as you explained, or model the other three implied quarters with 4 drivers and 4 pi loading.
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Scott-L: no problem and I appreciate your advice. I know the system is not for a room of this size, but build to learn (and also for the future: I will eventially move to a bigger house). I have direct radiators that I can use in stead of the midrange and midbass horn, but would like to explor this direction first to see where it leads me.
I do know several who have rigs like this and sitt in the very nearfield as this, but with a smaller midbass horn (Autotech's J-horn)
Best regards
Gisle
I do know several who have rigs like this and sitt in the very nearfield as this, but with a smaller midbass horn (Autotech's J-horn)
Best regards
Gisle
I have looked more into phase plug, compression chamber etc today, and came over this patent application which gave me some more valuable info on the subject:
http://patentimages.storage.googleapis.com/pdfs/US4157741.pdf
And of course there is this one:
http://www.centauriaudio.com.au/diy/plugs.html
http://patentimages.storage.googleapis.com/pdfs/US4157741.pdf
And of course there is this one:
http://www.centauriaudio.com.au/diy/plugs.html
Why are you looking into phase plugs, given the frequency range you are looking at?
Grist for the Horn Mill
Here are some articles covering the work of Smith, Murray and Small that you may find helpful regarding phase plug design and driver selection. The JBL CMCD technical note, included here as well, explains mid-bass horn implementation of these design regimes.
N.B.: Phase plugs with elongated passages provide the necessary control to permit formation and passage of a coherent wave front into the horn throat. The missions here are, HOM suppression and radiation pattern control in the far field. These issues have been addressed in other papers not included here. If interest persists, I will provide references to them later.
Regards,
WHG
Here are some articles covering the work of Smith, Murray and Small that you may find helpful regarding phase plug design and driver selection. The JBL CMCD technical note, included here as well, explains mid-bass horn implementation of these design regimes.
N.B.: Phase plugs with elongated passages provide the necessary control to permit formation and passage of a coherent wave front into the horn throat. The missions here are, HOM suppression and radiation pattern control in the far field. These issues have been addressed in other papers not included here. If interest persists, I will provide references to them later.
Regards,
WHG
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