>Should I taper a TL that implements a coupling chamber?
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It depends on the driver/app/performance goals.
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>Wich will give me better bass, coupling chamber or tapered line or a combination (if this last is feasible)?
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It depends on the driver/app. IMO, coupling chambers should be limited to low Q drivers. Can't really think of any more rules-of-thumb at the moment. Good pipe design falls under horn theory, so I recommend learning more about horn design.
GM
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It depends on the driver/app/performance goals.
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>Wich will give me better bass, coupling chamber or tapered line or a combination (if this last is feasible)?
====
It depends on the driver/app. IMO, coupling chambers should be limited to low Q drivers. Can't really think of any more rules-of-thumb at the moment. Good pipe design falls under horn theory, so I recommend learning more about horn design.
GM
TL and coupling chambers
A review of the Celestion 300 TL by Martin Colloms (in HiFi News Oct 92) mentions a couple of research papers that sound interesting on this subject. Their conclusion was (a) tapering the line has theoretical benefits which in practice may be ineffective and (b) the expansion or coupling chamber helps filter out higher order resonances. Celestion added a third trick by making the line start next to the driver, rather than at the opposite end of the coupling chamber.
I tried this out in a short TL using a Scanspeaker driver (about 10L for the chamber and a lightly filled line of about 1 metre) and it seemed to work ok. Bass occurs down to 50Hz, though in theory a 1 metre line shouldn't go this low.
The papers Colloms quotes are:
Roberts, M: "An acoustical model for transmission line woofer systems",
Letts, G: "A study of transmission line loudspeaker systems"
They both sound interesting. Anyone out there got copies?
Colin
A review of the Celestion 300 TL by Martin Colloms (in HiFi News Oct 92) mentions a couple of research papers that sound interesting on this subject. Their conclusion was (a) tapering the line has theoretical benefits which in practice may be ineffective and (b) the expansion or coupling chamber helps filter out higher order resonances. Celestion added a third trick by making the line start next to the driver, rather than at the opposite end of the coupling chamber.
I tried this out in a short TL using a Scanspeaker driver (about 10L for the chamber and a lightly filled line of about 1 metre) and it seemed to work ok. Bass occurs down to 50Hz, though in theory a 1 metre line shouldn't go this low.
The papers Colloms quotes are:
Roberts, M: "An acoustical model for transmission line woofer systems",
Letts, G: "A study of transmission line loudspeaker systems"
They both sound interesting. Anyone out there got copies?
Colin
If you are going to study horn design and principals (per GM) i highly recommend W. Marshall Leach Jr. papers from the AES website print # 1405. The math sometimes gets a little steep but once you lay it out on a spreadsheet and can jiggle the numbers it brings to light whats going on.(well sometimes)
ron
ron
Awwww Geeee Colin. Think of the endless hrs you can spend moving very heavy horns around trying to find that perfect bass response, the moving of furnature so some horn (the size of a small fridge) will fit.The endless excuses to wife or GF (honey , just try them for awile PLEASE), the hrs spent looking at a buncha numbers representing some kind of curve, the effort to make a flat piece of wood curve, hay the joys are endless LOL.
ron
ron
Hmm, my recommendation/question wasn't meant to drive anyone away, just get ya'll thinking along a proper design methodology. After all, compression drivers are tested using plane waves tubes, so if the design is such as to require an 'infinite' or partially blocked (slot loaded) rear chamber Vb, then the optimum 'front' chamber (low pass filter)/PWT can be calculated to a fair degree of accuracy for a given driver, and of course works for tapered also. 
As for trying to 'seduce' you back into horn building, I believe once someone starts exploring ALL the possibilities of pipe/horn design they'll never go back to a standard speaker box design.
GM
As for trying to 'seduce' you back into horn building, I believe once someone starts exploring ALL the possibilities of pipe/horn design they'll never go back to a standard speaker box design.
GM
I agree with GM. Despite the falts of horns i dont think i can or would go back to a normal enclosure.I was even looking into a different design to sub for horns as i have built several sets for friends (horns) and as far as i see it now if they want the same sound then it has to be a horn. if the wife or GF doset like it then so be it, let them live with mini-monitors and come over to my place when they want to hear what it SHOULD sound like.
ron
ron
I was very young at the time.
Actually the Klipsch-style horn did have a certain amount of respectability. It was based on a Wireless World design and later went into commercial production in the UK as the Lecson HL. The chopped-off mid-horn design later turned up in the commercial Impulse designs. And I was there at the beginning. I felt quite proud.
At the risk of hijacking the thread - what style and size of horns have you built? The zHorns and Buschorns look interesting but they can't be real horns at that size, can they?
Colin
PS Questions about horns - oh dear, this is how it all begins ...
Actually the Klipsch-style horn did have a certain amount of respectability. It was based on a Wireless World design and later went into commercial production in the UK as the Lecson HL. The chopped-off mid-horn design later turned up in the commercial Impulse designs. And I was there at the beginning. I felt quite proud.
At the risk of hijacking the thread - what style and size of horns have you built? The zHorns and Buschorns look interesting but they can't be real horns at that size, can they?
Colin
PS Questions about horns - oh dear, this is how it all begins ...
I designed and built my own.After intensive study into horn design there are many many factors that have to be considered.I am not going to put down anybodys work(happened to me and i dont see the point) but i dont believe in a "universal horn". IMHO a horn should be designed around the T/S parameters of a particular driver and the design criteria that you establish.
I was hung up on using the small fostex , but after lots of study i can see that a larger driver with the horn tuned higher (than .707 Fs of the smaller driver) will give a better response.After all a 50Hz horn is a 50Hz horn, just about the only major <(key word) difference in a larger driver is the cab is wider by a small amount.
Things i dont agree with in some horn designs are , mouth size being too small, trundicating the horn way beyond the initial goals, having the driver far away from the mouth and i wacked together a rear firing horn and i really couldnt get the sound i liked however this could have been largely room dependant.There appeared to be a time delay at the mechanical crossover that was apparent to me in the upper mid bass.
As a result i am designing around the fostex Fe-166e instead of the Fe-108 and using a front firing horn.
ron
I was hung up on using the small fostex , but after lots of study i can see that a larger driver with the horn tuned higher (than .707 Fs of the smaller driver) will give a better response.After all a 50Hz horn is a 50Hz horn, just about the only major <(key word) difference in a larger driver is the cab is wider by a small amount.
Things i dont agree with in some horn designs are , mouth size being too small, trundicating the horn way beyond the initial goals, having the driver far away from the mouth and i wacked together a rear firing horn and i really couldnt get the sound i liked however this could have been largely room dependant.There appeared to be a time delay at the mechanical crossover that was apparent to me in the upper mid bass.
As a result i am designing around the fostex Fe-166e instead of the Fe-108 and using a front firing horn.
ron
Horns
This was an attempt to build a smaller type horn for apt. use.I have sole several of them as a horn/gainclone combo and everybody that has heard them has been blown away.However the limitations are a relatively higher Fc (57 Hz,.707 x Fs) a sharp dropoff at LF and limited SPL.The Fe-103e is a good driver dont get me wrong but is limited in SPL and reaches x-max very early.I have also found out that the less folds the better and the smoother the radius ,on folds, the better.
ron
http://community.webtv.net/roncla/FOSTEXfe103ehorns
This was an attempt to build a smaller type horn for apt. use.I have sole several of them as a horn/gainclone combo and everybody that has heard them has been blown away.However the limitations are a relatively higher Fc (57 Hz,.707 x Fs) a sharp dropoff at LF and limited SPL.The Fe-103e is a good driver dont get me wrong but is limited in SPL and reaches x-max very early.I have also found out that the less folds the better and the smoother the radius ,on folds, the better.
ron
http://community.webtv.net/roncla/FOSTEXfe103ehorns
>I was very young at the time.
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Understood. Been there, done that, and I'm amazed I'm alive to admit it.
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>Actually the Klipsch-style horn did have a certain amount of respectability. It was based on a Wireless World design and later went into commercial production in the UK as the Lecson HL. The chopped-off mid-horn design later turned up in the commercial Impulse designs. And I was there at the beginning. I felt quite proud.
=====
You should! For the most part, I lived in a vacuum WRT audio until I got on the net in '96, so haven't read the mags over the decades or familiar with most of what's been offered over the decades, including the Lecson/Impulse. I would buy the yearly 'Buyer's Guides' though for the few visits to the HIFI Emporiums, but mostly have used prosound or older high end HIFI equipment I was familiar with.
It's been a bit of a blessing though since I learned by doing Vs being mislead by all the various 'rules-of-thumb', lastest n' greatest' designs, etc..
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>At the risk of hijacking the thread - what style and size of horns have you built?
=====
It seems to have died anyway, so might as well......
I haven't done a Klipschorn 'clone', I'm an Altec man, but have built just about everything else, from 70Hz dual driver midbass horns to diffraction tweeter ones in my quest for understanding since I'm too math challenged to learn/do from textbooks, athough Marshal Leach gave me many insights into horn theory right after he came to Atlanta back in '68 that would later show up in his AES papers. Combined with some insights from a structural engr. and my own simple measurements of numerous prototypes, I was able to piece together a fairly solid understanding of what goes on from flat baffle to 1/4WL, 1/2WL pipe and horn.
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>The zHorns and Buschorns look interesting but they can't be real horns at that size, can they?
=====
Anything that's flared is technically a horn. Obviously, due to their size and being fullrange driven, gain must be modest to keep from unduly affecting its higher BW abilities, closer to a TL than compression horn. Still, it's a good way to eek out another 1/2 octave or so of bottom end if a moderate Q driver is used. The ROT of using a low Q driver causes too much comb filtering between the driver/mouth if series resistance isn't used.
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>PS Questions about horns - oh dear, this is how it all begins ...
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Is the 'hook' sunk yet?
GM
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Understood. Been there, done that, and I'm amazed I'm alive to admit it.
=====
>Actually the Klipsch-style horn did have a certain amount of respectability. It was based on a Wireless World design and later went into commercial production in the UK as the Lecson HL. The chopped-off mid-horn design later turned up in the commercial Impulse designs. And I was there at the beginning. I felt quite proud.
=====
You should! For the most part, I lived in a vacuum WRT audio until I got on the net in '96, so haven't read the mags over the decades or familiar with most of what's been offered over the decades, including the Lecson/Impulse. I would buy the yearly 'Buyer's Guides' though for the few visits to the HIFI Emporiums, but mostly have used prosound or older high end HIFI equipment I was familiar with.
It's been a bit of a blessing though since I learned by doing Vs being mislead by all the various 'rules-of-thumb', lastest n' greatest' designs, etc..
=====
>At the risk of hijacking the thread - what style and size of horns have you built?
=====
It seems to have died anyway, so might as well......
I haven't done a Klipschorn 'clone', I'm an Altec man, but have built just about everything else, from 70Hz dual driver midbass horns to diffraction tweeter ones in my quest for understanding since I'm too math challenged to learn/do from textbooks, athough Marshal Leach gave me many insights into horn theory right after he came to Atlanta back in '68 that would later show up in his AES papers. Combined with some insights from a structural engr. and my own simple measurements of numerous prototypes, I was able to piece together a fairly solid understanding of what goes on from flat baffle to 1/4WL, 1/2WL pipe and horn.
=====
>The zHorns and Buschorns look interesting but they can't be real horns at that size, can they?
=====
Anything that's flared is technically a horn. Obviously, due to their size and being fullrange driven, gain must be modest to keep from unduly affecting its higher BW abilities, closer to a TL than compression horn. Still, it's a good way to eek out another 1/2 octave or so of bottom end if a moderate Q driver is used. The ROT of using a low Q driver causes too much comb filtering between the driver/mouth if series resistance isn't used.
=====
>PS Questions about horns - oh dear, this is how it all begins ...
=====
Is the 'hook' sunk yet?
GM
The hook was sort of already sunk (it's been hiding there, biding it's time for years).
Thanks for the info, both. At present I am plotting something with the Jordan JX92S driver - I know Ted and have had a chat with him about the TL on his website. (And I currently use one of his larger systems in a sealed cabinet.) I came across the zHorn as the designer had used the same unit in one of his smaller designs. (He's just produced a larger one using the larger Fostex, in case you haven't seen it, Ron).
Although I've gone through various magazines and such like over the years, the amount of info on the web has come as a pleasant surprise and forums like this are a delight. At one stage I produced cartoons for one or two of the UK hi-fi magazines. These days, I think the web is so far of the magazines it's laughable.
This could put household DIY on hold for a while though - first horns and now I've been to see what all the Gainclone fuss is about. Damn.
Colin
Thanks for the info, both. At present I am plotting something with the Jordan JX92S driver - I know Ted and have had a chat with him about the TL on his website. (And I currently use one of his larger systems in a sealed cabinet.) I came across the zHorn as the designer had used the same unit in one of his smaller designs. (He's just produced a larger one using the larger Fostex, in case you haven't seen it, Ron).
Although I've gone through various magazines and such like over the years, the amount of info on the web has come as a pleasant surprise and forums like this are a delight. At one stage I produced cartoons for one or two of the UK hi-fi magazines. These days, I think the web is so far of the magazines it's laughable.
This could put household DIY on hold for a while though - first horns and now I've been to see what all the Gainclone fuss is about. Damn.
Colin
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