Just yesterday I completed the first Horn loudspeaker of the two I designed some time before. The design is a rear folded horn with 2.2m length and the matching mouth, chamber etc tuned to 39Hz. The unit used is a front firing Tannoy HPD385 15" dual concentric monitor.
The Sound is trully excellent and crisp with very deep bass. The problem is that I noticed a booming in the lows and I guess I should tune the chamber with lining or something.
Any help towards the removal of this booming would be very appreciated. Please note that the test was done with only one unit in the room as the other is not completed yet.
The Sound is trully excellent and crisp with very deep bass. The problem is that I noticed a booming in the lows and I guess I should tune the chamber with lining or something.
Any help towards the removal of this booming would be very appreciated. Please note that the test was done with only one unit in the room as the other is not completed yet.
'Booming' horn, or room? Really, without driver specs, horn design and room details, there's no way to comment beyond generalities. For sure, damping the filter chamber will not affect a 'booming' horn other than to change its HF response.
GM
GM
Experiment with damping material (Dacron, Polyfill, Wool, etc)
starting from the throat and working out to the mouth. If that
doesn't do it, start at the mouth. If that doesn't do it, start in
the middle.
If that doesn't do it, try absorbent lining on the interior of the
horn surface, starting at the throat, etc.
If you know what you like when you hear it and are willing to
experiment, you will tend to get what you want.
😎
starting from the throat and working out to the mouth. If that
doesn't do it, start at the mouth. If that doesn't do it, start in
the middle.
If that doesn't do it, try absorbent lining on the interior of the
horn surface, starting at the throat, etc.
If you know what you like when you hear it and are willing to
experiment, you will tend to get what you want.
😎
Horn sessions
O.K, Firstly thanks alot GM and Nelsson for answering my post. You are right needing some more info, so, lets see:
Throat area 306 sq.cm
Chamber 30lt
Horn length 2,2m
Mouth area 2500 sq.cm
tuned to 39Hz
H1,21m, W0,49, D0,53 (external dimentions)
Exponential Expansion
After some listening sessions last night, using both units and playing with their positioning, I noticed most of the booming went away. Bass is excellent and cone movement is trully, at low input power coming from my Zen V5 (about 22W).
Overall very life like sound and very dynamic with good detail and speed, on the other hand the bass sound, seems to have a slight "tail" meaning its not absorbed extremely fast as it should, but leaves a "slowly" fading signature. I also noticed that the back of the cabinet vibrates alot when volume is high 95+db. I also should note that the listening session was done without any kind of internal stuffing or linning.
O.K, Firstly thanks alot GM and Nelsson for answering my post. You are right needing some more info, so, lets see:
Throat area 306 sq.cm
Chamber 30lt
Horn length 2,2m
Mouth area 2500 sq.cm
tuned to 39Hz
H1,21m, W0,49, D0,53 (external dimentions)
Exponential Expansion
After some listening sessions last night, using both units and playing with their positioning, I noticed most of the booming went away. Bass is excellent and cone movement is trully, at low input power coming from my Zen V5 (about 22W).
Overall very life like sound and very dynamic with good detail and speed, on the other hand the bass sound, seems to have a slight "tail" meaning its not absorbed extremely fast as it should, but leaves a "slowly" fading signature. I also noticed that the back of the cabinet vibrates alot when volume is high 95+db. I also should note that the listening session was done without any kind of internal stuffing or linning.
Photos
And here is a link containing some photos of the project just to know what are we talking about.
http://audio.dynatech.gr/horny.htm
And here is a link containing some photos of the project just to know what are we talking about.
http://audio.dynatech.gr/horny.htm
Greets!
You're welcome! Using some measured specs by others, simming a 30L filter chamber makes this more a slightly underdamped bass reflex with a huge vent than a BLH, and if there's any series resistance (amp output, too small a wire, etc.) it will be more underdamped, so NP's suggestion to damp the mouth will stop the 'ringing' (your slight 'tail'). This will reduce peak output a bit which will help with blending to the room better, allowing more placement flexibility.
It probably won't take much to damp it, so I recommend making a grill for the mouth and experiment either with different density cloths or a very open weave and as many layers as required.
Also, adding some mass loading to the driver to better balance out the driver's front/rear loading is theoretically a 'good plan', so if you're up to it, try different 'throats' on the front of the driver to see if it helps the overall performance. Optimize this before damping the mouth if you decide to try it.
A 2:1 CR usually works pretty good, so for a first approximation try ~222 mm diameter. I'm not familiar with the Tannoy horn's polar response so you may have to damp the inside of it, and I recommend you chamfer it at 45 deg to reduce the amplitude of its reflections and/or standing waves.
And or course more stiffening is required on the back and the mouth. You look like you're having way too much fun building these! 🙂
Anyway, let us know what works best for you.
GM
You're welcome! Using some measured specs by others, simming a 30L filter chamber makes this more a slightly underdamped bass reflex with a huge vent than a BLH, and if there's any series resistance (amp output, too small a wire, etc.) it will be more underdamped, so NP's suggestion to damp the mouth will stop the 'ringing' (your slight 'tail'). This will reduce peak output a bit which will help with blending to the room better, allowing more placement flexibility.
It probably won't take much to damp it, so I recommend making a grill for the mouth and experiment either with different density cloths or a very open weave and as many layers as required.
Also, adding some mass loading to the driver to better balance out the driver's front/rear loading is theoretically a 'good plan', so if you're up to it, try different 'throats' on the front of the driver to see if it helps the overall performance. Optimize this before damping the mouth if you decide to try it.
A 2:1 CR usually works pretty good, so for a first approximation try ~222 mm diameter. I'm not familiar with the Tannoy horn's polar response so you may have to damp the inside of it, and I recommend you chamfer it at 45 deg to reduce the amplitude of its reflections and/or standing waves.
And or course more stiffening is required on the back and the mouth. You look like you're having way too much fun building these! 🙂
Anyway, let us know what works best for you.
GM
I spelled it wrong, what I wanted to say is that I cannot see any cone movement at least with 22W input, which are enough for 110db output at 1m(measured).
Now, what do you mean by underdamped? 30L is more than needed or less ?
Do I have to limit the volume of the chamber(doable) and or limit the throat area?
Why should I add mass to the LF driver and why should I do it? What is 2:1 CR? can you be a little more specific?
Sorry for my ignorance, but it is my first try designing a horn from scratch and there is obviously a long way for me to go.
However, the sound is excellent for my taste(very lifi like) even without any tuning and I believe I can make it even better with some tuning as you suggested.
Regards,
Panos
Now, what do you mean by underdamped? 30L is more than needed or less ?
Do I have to limit the volume of the chamber(doable) and or limit the throat area?
Why should I add mass to the LF driver and why should I do it? What is 2:1 CR? can you be a little more specific?
Sorry for my ignorance, but it is my first try designing a horn from scratch and there is obviously a long way for me to go.
However, the sound is excellent for my taste(very lifi like) even without any tuning and I believe I can make it even better with some tuning as you suggested.
Regards,
Panos
Re: Photos
We have several pairs of those Tannoys, and love them greatly.
I have a pair going into some folded "Voigt" enclosures right
now, and I'll let you know how it works out.
In the meantime, like I say, be prepared to play with the
stuffing.
panos29 said:
We have several pairs of those Tannoys, and love them greatly.
I have a pair going into some folded "Voigt" enclosures right
now, and I'll let you know how it works out.
In the meantime, like I say, be prepared to play with the
stuffing.
>Now, what do you mean by underdamped?
====
Technically, an alignment that is not critically damped and has some 'overshooting' of a transient before 'letting go', delaying the decay of the signal.
====
>30L is more than needed or less ? Do I have to limit the volume of the chamber(doable) and or limit the throat area?
====
Too small for this version of a BLH.
====
>Why should I add mass to the LF driver and why should I do it? What is 2:1 CR? can you be a little more specific?
====
Compression ratio, the ratio of the driver's Sd to throat area.
Drivers want to 'feel' a balanced load on both sides of the diaphragm and all the ones that most folks seem to think have the 'right' specs for a BLH ideally require a M = ~0.5 and flare rate down below 10Hz, so any 'faster' flare rate, and especially with a much 'faster' M factor, requires some mass loading to offset them. Really, they need sealed rear compression chambers, but then they wouldn't be BLHs anymore, but I've found that some loading is better than none. 😉
====
>Sorry for my ignorance, but it is my first try designing a horn from scratch and there is obviously a long way for me to go.
====
Understood, you don't master them the first time out since horns are so 'adjustable', like a F1 racer's multi-link suspension system.
====
>However, the sound is excellent for my taste(very lifi like) even without any tuning and I believe I can make it even better with some tuning as you suggested.
====
'Sounds' like you're off to a great start then! 🙂
GM
====
Technically, an alignment that is not critically damped and has some 'overshooting' of a transient before 'letting go', delaying the decay of the signal.
====
>30L is more than needed or less ? Do I have to limit the volume of the chamber(doable) and or limit the throat area?
====
Too small for this version of a BLH.
====
>Why should I add mass to the LF driver and why should I do it? What is 2:1 CR? can you be a little more specific?
====
Compression ratio, the ratio of the driver's Sd to throat area.
Drivers want to 'feel' a balanced load on both sides of the diaphragm and all the ones that most folks seem to think have the 'right' specs for a BLH ideally require a M = ~0.5 and flare rate down below 10Hz, so any 'faster' flare rate, and especially with a much 'faster' M factor, requires some mass loading to offset them. Really, they need sealed rear compression chambers, but then they wouldn't be BLHs anymore, but I've found that some loading is better than none. 😉
====
>Sorry for my ignorance, but it is my first try designing a horn from scratch and there is obviously a long way for me to go.
====
Understood, you don't master them the first time out since horns are so 'adjustable', like a F1 racer's multi-link suspension system.
====
>However, the sound is excellent for my taste(very lifi like) even without any tuning and I believe I can make it even better with some tuning as you suggested.
====
'Sounds' like you're off to a great start then! 🙂
GM
Dear Nelsson,
I am already playing with stuffing with very good results and I am really very enthousiastic to know you are playing with these units too! I also believe that the crossover need some upgreating if not complete redesign as in you beautifull article about crossovers. Moreover I would likto hear more about your Voigt foldedpipes!
Dear GM,
Thanks alot for all the details you gave me about your previous answers, I just wanted to add that Sd=770sq.cm thus 306sq.cm seems more logical than 220 you suggest, however, I can try your proposal easily as I have good access to the mouth.
Given Fs=22Hz, Vas=483lt, Qes=0.2, Qms=2,4, Qts=0.18, Cms=0.58mm/N, Mms=90gr, Sd=770sq.cm, Bl=18.72N/A and sensitivity = 94,3dB/2,83V, what is the drivers M?
I am already playing with stuffing with very good results and I am really very enthousiastic to know you are playing with these units too! I also believe that the crossover need some upgreating if not complete redesign as in you beautifull article about crossovers. Moreover I would likto hear more about your Voigt foldedpipes!
Dear GM,
Thanks alot for all the details you gave me about your previous answers, I just wanted to add that Sd=770sq.cm thus 306sq.cm seems more logical than 220 you suggest, however, I can try your proposal easily as I have good access to the mouth.
Given Fs=22Hz, Vas=483lt, Qes=0.2, Qms=2,4, Qts=0.18, Cms=0.58mm/N, Mms=90gr, Sd=770sq.cm, Bl=18.72N/A and sensitivity = 94,3dB/2,83V, what is the drivers M?
>Dear GM,
>Thanks alot for all the details you gave me about your previous answers, I just wanted to add that Sd=770sq.cm thus 306sq.cm seems more logical than 220 you suggest, however, I can try your proposal easily as I have good access to the mouth.
====
First, for a 2:1 CR we want a throat which is half of 770cm^2, or 385cm^2, i.e. a diameter 0.707x the effective diameter. Second, I said 222 mm 'diameter', or ~387cm^2, which is close enough, though if you have the ability to accurately measure 221.4mm, then you can get it exact if you're a perfectionist. Regardless, Sd isn't a real accurate measurement to start with, so if you wanted to do this really accurately you would have to find the point on the diaphragm where the mass corner frequency (Fh) launches off the diaphragm to find the diameter and chamfer angle.
====
>Given Fs=22Hz, Vas=483lt, Qes=0.2, Qms=2,4, Qts=0.18, Cms=0.58mm/N, Mms=90gr, Sd=770sq.cm, Bl=18.72N/A and sensitivity = 94,3dB/2,83V, what is the drivers M?
====
'M' (AKA 'T') isn't a driver parameter, but a horn flare factor based on a 'family' of curves where 0 = catenoidal, 0.5 = hyperbolic, and 1 = exponential.
GM
>Thanks alot for all the details you gave me about your previous answers, I just wanted to add that Sd=770sq.cm thus 306sq.cm seems more logical than 220 you suggest, however, I can try your proposal easily as I have good access to the mouth.
====
First, for a 2:1 CR we want a throat which is half of 770cm^2, or 385cm^2, i.e. a diameter 0.707x the effective diameter. Second, I said 222 mm 'diameter', or ~387cm^2, which is close enough, though if you have the ability to accurately measure 221.4mm, then you can get it exact if you're a perfectionist. Regardless, Sd isn't a real accurate measurement to start with, so if you wanted to do this really accurately you would have to find the point on the diaphragm where the mass corner frequency (Fh) launches off the diaphragm to find the diameter and chamfer angle.
====
>Given Fs=22Hz, Vas=483lt, Qes=0.2, Qms=2,4, Qts=0.18, Cms=0.58mm/N, Mms=90gr, Sd=770sq.cm, Bl=18.72N/A and sensitivity = 94,3dB/2,83V, what is the drivers M?
====
'M' (AKA 'T') isn't a driver parameter, but a horn flare factor based on a 'family' of curves where 0 = catenoidal, 0.5 = hyperbolic, and 1 = exponential.
GM
Satisfied!
Now that I auditioned my horns for some time, I have to make some comments as far as the sound quality is concerned.
First of all the speakers are trully excellent! I start liking the sound alot! The music is flowing in a very natural way and I catch myshelf to listen at 100+db, something I never did before!
Very analytical with very live and alive bass and abient feeling, like you are in a concert hall!
I also experimented with stuffing of the back chamber from full to just a thin "film" of lining on th walls of the compression chamber.
I noticed that when full, the life is completely gone!
The sound became similar to a good reflex box!
I finally settled for a thin layer in the chamber walls. I also played with positioning and the booming is almost gone now.
Also noticed that 6W are more than enough.
I do not really know if I have to try limiting the throat area as I am very satisfied as is and I do not rally know if I can gain more, I really cannot understand how much better can it get.
I also auditioned it with many friends and all are extremely surprised and really loved it, to the point that most of them are now looking for these drivers in ebay!
On more point, my Zen V5 is an excellent mate for these!
Now that I auditioned my horns for some time, I have to make some comments as far as the sound quality is concerned.
First of all the speakers are trully excellent! I start liking the sound alot! The music is flowing in a very natural way and I catch myshelf to listen at 100+db, something I never did before!
Very analytical with very live and alive bass and abient feeling, like you are in a concert hall!
I also experimented with stuffing of the back chamber from full to just a thin "film" of lining on th walls of the compression chamber.
I noticed that when full, the life is completely gone!
The sound became similar to a good reflex box!
I finally settled for a thin layer in the chamber walls. I also played with positioning and the booming is almost gone now.
Also noticed that 6W are more than enough.
I do not really know if I have to try limiting the throat area as I am very satisfied as is and I do not rally know if I can gain more, I really cannot understand how much better can it get.
I also auditioned it with many friends and all are extremely surprised and really loved it, to the point that most of them are now looking for these drivers in ebay!
On more point, my Zen V5 is an excellent mate for these!
- Status
- Not open for further replies.