OK, I am back. Had to get some work done this afternoon to keep the boss happy so I dropped out of the discussion. Here are some answers to various posts.
You have picked two designs for which I do not have simulations. I have simulated probably 20 - 40 BLH over the past few years looking for a "good" design. I have not found one that I felt was worth building yet. If you are interested in a particular horn I would suggest modeling it in my BLH worksheet to see what the response looks like and if it is worth building.
TL's also emit a double pulse response due to the wave traveling down the pipe before exiting into the room. Is this audible, don't know and I have seen convincing arguments both ways.
I don't know anything about the Tannoy so I have nothing to add. We did have a good discussion about the Replikon horn a few months back and I liked what I saw in the response. Onur also has a similar horn design that looked interesting. These are the best performing BLH designs, on paper, that I have seen.
Now let me throw out a question for discussion.
Scott's last plot for the Hedlund horn showed a reasonable output down to about 70 Hz. There were a few significant ripples but the response was basically flat. This would be the predicted response if the speaker were mounted in a wall so the driver and the mouth radiated into the room. I have not heard the Hedlund horn but have been told that the deep bass is lacking and a sub is needed, that matches Scott's simulation results.
So for the Hedlund horn to achieve a real in room response similar to Scott's simulation, you are going to need to corner load it or add a correction circuit with the associated loss of efficiency. Out in the room one should anticipate a 3 or 4 dB loss of bass due to baffle step, probably everything below 400 Hz will be attenuated.
1. The Hedlund horn is a work of woodworking art, big and difficult to construct. Definitely an eye catcher in anybody's room.
2. The same FE-206E in a ML TL design (my design or Bob Brines' design) with a correction circuit can produce a flatter response all the way down to 40 Hz with some associated loss of efficiency. No big wiggles. Smaller and easy construction. No sub needed.
Why build a Hedlund horn?
I asked this same question of a Hedlund horn owner and the only real good response he could provide, in my opinion, was that he felt that the correction circuit would remove detail from the recording. He uses a sub for bass. He had not tried a circuit. My experience has shown me that the circuit only rebalances the SPL response with no loss of any detail or sound quality.
So tell me, why would one build a Hedlund horn over some other less complicated design? No right or wrong answer to this question. Just for discussion.
You have picked two designs for which I do not have simulations. I have simulated probably 20 - 40 BLH over the past few years looking for a "good" design. I have not found one that I felt was worth building yet. If you are interested in a particular horn I would suggest modeling it in my BLH worksheet to see what the response looks like and if it is worth building.
TL's also emit a double pulse response due to the wave traveling down the pipe before exiting into the room. Is this audible, don't know and I have seen convincing arguments both ways.
I don't know anything about the Tannoy so I have nothing to add. We did have a good discussion about the Replikon horn a few months back and I liked what I saw in the response. Onur also has a similar horn design that looked interesting. These are the best performing BLH designs, on paper, that I have seen.
Now let me throw out a question for discussion.
Scott's last plot for the Hedlund horn showed a reasonable output down to about 70 Hz. There were a few significant ripples but the response was basically flat. This would be the predicted response if the speaker were mounted in a wall so the driver and the mouth radiated into the room. I have not heard the Hedlund horn but have been told that the deep bass is lacking and a sub is needed, that matches Scott's simulation results.
So for the Hedlund horn to achieve a real in room response similar to Scott's simulation, you are going to need to corner load it or add a correction circuit with the associated loss of efficiency. Out in the room one should anticipate a 3 or 4 dB loss of bass due to baffle step, probably everything below 400 Hz will be attenuated.
1. The Hedlund horn is a work of woodworking art, big and difficult to construct. Definitely an eye catcher in anybody's room.
2. The same FE-206E in a ML TL design (my design or Bob Brines' design) with a correction circuit can produce a flatter response all the way down to 40 Hz with some associated loss of efficiency. No big wiggles. Smaller and easy construction. No sub needed.
Why build a Hedlund horn?
I asked this same question of a Hedlund horn owner and the only real good response he could provide, in my opinion, was that he felt that the correction circuit would remove detail from the recording. He uses a sub for bass. He had not tried a circuit. My experience has shown me that the circuit only rebalances the SPL response with no loss of any detail or sound quality.
So tell me, why would one build a Hedlund horn over some other less complicated design? No right or wrong answer to this question. Just for discussion.
Greets!
For a given listening distance there is a loss of detail, etc., due to non-linear and often thermal power distortions when efficiency is traded for BW. For instance, you find the Fostex/Lowther quite acceptable tuned low with plenty of series R/BSC, but I had to get into the nearfield of Bob Brine's and other's FR speakers to find them ~acceptable. Too much exposure to effortless dynamics and the low level detail that only HE systems can provide I guess.
GM
For a given listening distance there is a loss of detail, etc., due to non-linear and often thermal power distortions when efficiency is traded for BW. For instance, you find the Fostex/Lowther quite acceptable tuned low with plenty of series R/BSC, but I had to get into the nearfield of Bob Brine's and other's FR speakers to find them ~acceptable. Too much exposure to effortless dynamics and the low level detail that only HE systems can provide I guess.
GM
Sounds plausable enough I suppose. The only argument I can find for building the Hedlund is either a person desperately wants a horn for aesthetic reasons, they have a flea power SET power amp (sub 3 watt job), or a very large room, or a combination of all three, in which case efficiency is all and a Hedlund rammed into room corners and a pair of additional active subwoofers would probably do the job.
I'm ultimately with Martin on this one though I'm afraid. The Hedlund is a spectacular looking beast; for what it is, it's a reasonably good example of the breed, and I'd say that if you want to build a 'horn' this is the best design I've simulated, apart from the Replikon and Omar's double-horn -both of which fly very much in the face of conventional horn-design thinking. It would also be a real conversation piece in any room it's situated in (looks like something formed by the sea, doesn't it). However, I believe that most people would get considerably superior results from a much simpler enclosure, i.e. deeper bass, a flatter response etc like Martin's or Bob's MLTL designs.
I roughly modelled those different horns a while back in Martin's worksheets for the same reason Martin mentioned: to see if any were worth building. I came to the same conclusion Martin did, noting that the Hedlund was probably the best of the breed at the time, with the sole exception of the old Tannoy GRF Signiture cabinets intended for their 15" Silver, Red and Gold Duel Concentric 2 way drivers, and I stuck to Mass Loaded Transmission Lines of various tapers, and moved toward open baffles too -a combination of Martin's work, and Siegfried Linkwitz'. I have not personally encountered any changes (i.e.) removal) in detail with any sensible BSC circuit in place with an approipriately powerful amplifier, and with a high quality DSP, you wouldn't even need that.
I think it all boils back down to listening preferences -we all hear differently anyway, and what is realistic to one is not so to another, who values different things, and probably listens to different music styles and types too.
All the best
Scott
I'm ultimately with Martin on this one though I'm afraid. The Hedlund is a spectacular looking beast; for what it is, it's a reasonably good example of the breed, and I'd say that if you want to build a 'horn' this is the best design I've simulated, apart from the Replikon and Omar's double-horn -both of which fly very much in the face of conventional horn-design thinking. It would also be a real conversation piece in any room it's situated in (looks like something formed by the sea, doesn't it). However, I believe that most people would get considerably superior results from a much simpler enclosure, i.e. deeper bass, a flatter response etc like Martin's or Bob's MLTL designs.
I roughly modelled those different horns a while back in Martin's worksheets for the same reason Martin mentioned: to see if any were worth building. I came to the same conclusion Martin did, noting that the Hedlund was probably the best of the breed at the time, with the sole exception of the old Tannoy GRF Signiture cabinets intended for their 15" Silver, Red and Gold Duel Concentric 2 way drivers, and I stuck to Mass Loaded Transmission Lines of various tapers, and moved toward open baffles too -a combination of Martin's work, and Siegfried Linkwitz'. I have not personally encountered any changes (i.e.) removal) in detail with any sensible BSC circuit in place with an approipriately powerful amplifier, and with a high quality DSP, you wouldn't even need that.
I think it all boils back down to listening preferences -we all hear differently anyway, and what is realistic to one is not so to another, who values different things, and probably listens to different music styles and types too.
All the best
Scott
Hi!
Scott: I did my own simulations and get very similar to yours. I can say too, that the Hedlund give the best from the another design i.e.: Fostex 166 ES-R, Nagaoka D-37, Isophon.
I know the MLTL designs are simple and give very nice responses, but for me they are sounding like BR types, what are not bad, but I am missing the "magic" what a good TML give to me. Of course, it is matter of taste.....
Until now I have built several loudspeakers: Closed, BR, TQWT, MLTL, and TLs, but BLH not yet. This is why am I looking for a good BLH design what could give linear response down to 40 Hz.
Greets:
Tyimo
Scott: I did my own simulations and get very similar to yours. I can say too, that the Hedlund give the best from the another design i.e.: Fostex 166 ES-R, Nagaoka D-37, Isophon.
You say there are many simpler enclosure what would give better, deeper bass and flatter response, but maybe there is something more over this parameters what makes the BLHs so popular. For example nowadays in Japan it is the most favourited kind of enclosure.
I know the MLTL designs are simple and give very nice responses, but for me they are sounding like BR types, what are not bad, but I am missing the "magic" what a good TML give to me. Of course, it is matter of taste.....
Until now I have built several loudspeakers: Closed, BR, TQWT, MLTL, and TLs, but BLH not yet. This is why am I looking for a good BLH design what could give linear response down to 40 Hz.
Greets:
Tyimo
Have you thought about a double bass reflex ?
I have several reasons for not liking conventional bass-reflex :
- the commercial BR have small volumes, small ports and therefore emit horrible port noises
- the standard BR enclosure has parallel sides : if they are not properly dimensionned, standing waves issues may appear
- with efficient drivers, the mid and highs coming out from the port may be so strong that they almost reach the dirver's SPL, causing this loss of details people don't like.
I like TLs and TQWTs because they are "made to be damped" and strategical damping may reduce dramatically the mids and highs coming out from the port.
They have big ports unlike to whistle.
The damping inside ensures a very good damping of the internal reflexions, standing waves... resulting in a clean impulse response.
I have recently simulated Supravox drivers in for a friend : these drivers are very efficient for 16cm units : 97dB !!
It appears that even in a TQWT, the mid an highs can still go through the port at unacceptable levels : -7dB @ 1kHz
So, I designed a double bass reflex for it, and the simulation gives me -35dB at the port @ 1kHz ! In fact, the level is decreased under -20dB after 200Hz, which is a nice thing !
I assume the principle of a DBR enclosure is to have a principal volume behind the driver, with the port giving in a second box that plays the role of a low-pass filter, and a furthermore bass increase (though still limited to a normal DBR performance).
Moreover, the different tunings allow to build a response that increases under 100Hz to compensate partially baffle step diffraction.
Impluse looks very clean.
I may not tell how it really sounds but I'm sure it will perform very well (the speakers are not built at this time)
Maybe it can be worth doing this if you wanna keep the driver's inner qualities above 100Hz. It is also an enclosure you never tried isn't it ?
Just my 2c
I have several reasons for not liking conventional bass-reflex :
- the commercial BR have small volumes, small ports and therefore emit horrible port noises
- the standard BR enclosure has parallel sides : if they are not properly dimensionned, standing waves issues may appear
- with efficient drivers, the mid and highs coming out from the port may be so strong that they almost reach the dirver's SPL, causing this loss of details people don't like.
I like TLs and TQWTs because they are "made to be damped" and strategical damping may reduce dramatically the mids and highs coming out from the port.
They have big ports unlike to whistle.
The damping inside ensures a very good damping of the internal reflexions, standing waves... resulting in a clean impulse response.
I have recently simulated Supravox drivers in for a friend : these drivers are very efficient for 16cm units : 97dB !!
It appears that even in a TQWT, the mid an highs can still go through the port at unacceptable levels : -7dB @ 1kHz
So, I designed a double bass reflex for it, and the simulation gives me -35dB at the port @ 1kHz ! In fact, the level is decreased under -20dB after 200Hz, which is a nice thing !
I assume the principle of a DBR enclosure is to have a principal volume behind the driver, with the port giving in a second box that plays the role of a low-pass filter, and a furthermore bass increase (though still limited to a normal DBR performance).
Moreover, the different tunings allow to build a response that increases under 100Hz to compensate partially baffle step diffraction.
Impluse looks very clean.
I may not tell how it really sounds but I'm sure it will perform very well (the speakers are not built at this time)
Maybe it can be worth doing this if you wanna keep the driver's inner qualities above 100Hz. It is also an enclosure you never tried isn't it ?
Just my 2c
Hi!
I already asked this question in another threads, but didn' get answer yet, so I will try to ask here too:
How could I calculate the horn bend/curve/fold geometry? I mean:
How can I calculate, draw and bend a straight exponential horn contour into ca. 270 grade bend like in the attached photo??
Tyimo
I already asked this question in another threads, but didn' get answer yet, so I will try to ask here too:
How could I calculate the horn bend/curve/fold geometry? I mean:
How can I calculate, draw and bend a straight exponential horn contour into ca. 270 grade bend like in the attached photo??
Tyimo
Attachments
Tyimo said:
Is this pretty similar to what you're trying get?
http://www2.mat.dtu.dk/people/V.L.Hansen/nautilus/naustory.html
qi said:
?? Any well designed system with >97 dB/W/m down to at least 40 Hz in-room qualifies. I prefer compression driven midbass/mids/HF horns, but something like the Basszilla with a DX4 and more efficient bottom end works for me and my preference over a 'fullrange' BLH. In between these two 'extremes' would be a waveguide loaded FR driver and ~matching efficiency midbass horn. Here, the BLH makes much more sense to me since the 100-250 Hz XO gets rid of its problematic mids matching.
GM
Tyimo said:Hi!
Thanks! Yes, I think it could be similar, but I have to re-read that site, because this Nautilus Math is realy "heavy" for me)
Tyimo
This site has some simple drawing tips.
http://jwilson.coe.uga.edu/emt669/Student.Folders/Frietag.Mark/Homepage/Goldenratio/goldenratio.html
Greets!
No, I said "....something like the Basszilla with a DX4 and more efficient bottom end" since I'm not aware of a lone HE driver that can meet the efficiency/BW criteria in a typical room, but then I don't keep up with what all is available, so I may be somewhat 'dated'.
I had no specific currently available designs in mind (this is a DIY forum after all), though I imagine that B-D Designs, Pi Speakers, possibly Azura, has at least one model that can meet the requirements. Then of course there's Bruce Edgar's systems, some Altec, JBL, Klipsch vintage systems, as well as currently available JBL, etc., cinema systems ($$$/huge) that can exceed the requirements by a wide margin.
Something I meant to say about using a BLH as woofer system only is that since regulating its gain to blend with a specific driver isn't required, a ~optimum design can be used (much higher gain). There may be some prosound scoop bins that meet the 40 Hz in-room criteria, but the few I'm familiar with roll off too much below 60 Hz to do it.
Awhile back someone asked me what a truly optimized BLH would theoretically be capable of, so for 'giggles' I loaded the JBL 2226 horn driver's specs into Leach's math and it spit out an aneochoically flat 6.6 Hz Fc design with >97 dB/W/m efficiency. With only a 600W PE, we're not going to recreate thunder, or a bomb blast, but it will cover any music, including pipe organ, drum, etc., subharmonics. Also, to maintain the tonal balance of the 20-20 kHz BW reference, we'll theoretically need >97 dB efficient HF extension out to ~60,633 Hz, which presents some design challenges too. Then there's the problem of getting sufficently 'clean'/flat wide BW from the signal chain.
Needless to say this system would be ridiculously large and not for the impecunious or hearing 'faint of heart', and if we use a lower Fs HE driver such as the JBL 2245, or just more drivers, then we can get closer to 'Mother Nature's' near DC capability, though at only an infinitesimally small fraction of 'her' peak amplitudes.
GM
No, I said "....something like the Basszilla with a DX4 and more efficient bottom end" since I'm not aware of a lone HE driver that can meet the efficiency/BW criteria in a typical room, but then I don't keep up with what all is available, so I may be somewhat 'dated'.
I had no specific currently available designs in mind (this is a DIY forum after all), though I imagine that B-D Designs, Pi Speakers, possibly Azura, has at least one model that can meet the requirements. Then of course there's Bruce Edgar's systems, some Altec, JBL, Klipsch vintage systems, as well as currently available JBL, etc., cinema systems ($$$/huge) that can exceed the requirements by a wide margin.
Something I meant to say about using a BLH as woofer system only is that since regulating its gain to blend with a specific driver isn't required, a ~optimum design can be used (much higher gain). There may be some prosound scoop bins that meet the 40 Hz in-room criteria, but the few I'm familiar with roll off too much below 60 Hz to do it.
Awhile back someone asked me what a truly optimized BLH would theoretically be capable of, so for 'giggles' I loaded the JBL 2226 horn driver's specs into Leach's math and it spit out an aneochoically flat 6.6 Hz Fc design with >97 dB/W/m efficiency. With only a 600W PE, we're not going to recreate thunder, or a bomb blast, but it will cover any music, including pipe organ, drum, etc., subharmonics. Also, to maintain the tonal balance of the 20-20 kHz BW reference, we'll theoretically need >97 dB efficient HF extension out to ~60,633 Hz, which presents some design challenges too. Then there's the problem of getting sufficently 'clean'/flat wide BW from the signal chain.
Needless to say this system would be ridiculously large and not for the impecunious or hearing 'faint of heart', and if we use a lower Fs HE driver such as the JBL 2245, or just more drivers, then we can get closer to 'Mother Nature's' near DC capability, though at only an infinitesimally small fraction of 'her' peak amplitudes.
GM
Yes, it should be possible to estimate the Helmholtz resonance of a bass reflex box with an exponential shaped port. No, I don't have a equation already derived. But using a little calculus to integrate and find the exponential port's volume, and being careful to determine an accurate end correction for the mouth, an expression could be derived.
Or, you could just plug the geometry into my BLH worksheet and see where the first peak is in the acoustic impedance plot. That should be very accurate.
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