10" Front loaded sub design THE RADIHORN |
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drbis84
New Member Joined: 07 March 2012 Status: Offline Points: 7 |
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Posted: 07 March 2012 at 10:32pm |
Hello everyone,
I am a newbie with a project in mind, but I'm full of doubts and I need your expert opinion to see if it can work. I have two 10" car subs (AUDIO SYSTEM - RADION 10 PLUS) and I found a plan of an old 10" back-loaded horn that I have slightly changed by reversing the cone and adding a closed rear chamber. The result is the following: I tryed to model it with hornresp with the following results: I also imported it in Akabak to simulate subsonic filter and low pass filter. High pass 35Hz 24db - Low pass 85Hz 24db The music I like is reggae roots and dub and I want to use it both outdoor and indoor. I know it is ONLY a 10" so I don't expect to destroy buildings with two of these horns. Just some good bass (at least louder than a 60L with Fb 35Hz). My first and greatest doubt is about group delay peaks at 40Hz and ~100Hz. Mainly the ~100Hz one! The only horn I've heard is PD1850 SUPER SCOOPER which for my ears is fast enough when playing dub music. I know that 10" is not 18" but what I want to understand is if group delay is so bad. I found this simulation with hornresp and you can see that group delay is quite similar (PD1850 black - RADION10PLUS grey). I can also add a delay of ~8/10ms on the mid-highs so that group delay between 60-80Hz can be considered as near 0ms. Second doubt is about cone displacement. If xmax is 8mm can I consider 10-12mm to be the xmech? What happens in sealed rear chamber with displacement greater than xmax? Will the sub get too "hot"? Is a rear vented chamber tuned to about 30Hz a good idea? Even lower to take port group delay peak not over the 40Hz existing group delay. Third doubt is about the wood thickness and foldings. Is 16mm chipboard acceptable without bracing? Internal cab width is 40cm. Are there too many folds in your opinion? Will they change the response too much? I'd be really grateful if you help me with your answers and your comments. If I said too much rubbish please correct me as much as you can. Thanks in advance. |
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drbis84
New Member Joined: 07 March 2012 Status: Offline Points: 7 |
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Another image taken from cad rendering.
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Disco Stu
Old Croc Joined: 03 March 2005 Location: United Kingdom Status: Offline Points: 2487 |
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Bit of a waste of space in the middle isnt it? you could have the magnet of the driver facing the \ angled panel with the access door in there and subsequently either shorten the height of the cab keeping the same length horn or extend the horn length by about another 2 folds.
Stu
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All you need to know is:
Sensitivity + Power Handling - Power Compression = Max Output My acts: www.myspace.com/thebowiexperience www.myspace.com/scheisseelektronisches |
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djeddie
Old Croc Joined: 26 April 2004 Location: Bristol Status: Offline Points: 4125 |
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As Stu said.
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Chas n Dave : it's like Drum and Bass but with beards. E=mc² ±3dB
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drbis84
New Member Joined: 07 March 2012 Status: Offline Points: 7 |
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Thanks for your quick reply.
You are right about the waste of space but I'm not so expert in cutting wood so it would be much easier for me to make it in this way because most of the panels are 90 degrees. For the moment I can consider the height acceptable but for sure this could be a good improvement. What do you think about my doubts? Thanks again for your reply |
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drbis84
New Member Joined: 07 March 2012 Status: Offline Points: 7 |
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What I mean is that I would like to discuss first about my doubts to understand if such design could be considered theorically good or if it's a total waste of time.
Your improvement is good and will consider it when it will be time to think deeply about construction. Thanks again |
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Disco Stu
Old Croc Joined: 03 March 2005 Location: United Kingdom Status: Offline Points: 2487 |
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While I know nothing about the theory (you seem to have a grasp of akabak) the Stasys X from Void I believe has a second chamber which acts as a resonator. If you were to port the top chamber into the currently wasted space chamber you might be able to get some additional LF output? As I say its entirely a theory and someone with better knowledge than me would have to answer. As it is, yes the Xmax could potentially be a problem, hence why I suggested lengthening the horn a little more, alternatively I would use a steep 24dB per octave roll off on the bottom end around 45-50Hz Stu |
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All you need to know is:
Sensitivity + Power Handling - Power Compression = Max Output My acts: www.myspace.com/thebowiexperience www.myspace.com/scheisseelektronisches |
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drbis84
New Member Joined: 07 March 2012 Status: Offline Points: 7 |
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I already had the same idea and tried to understand the principles of Stasys obviously with no result.
One practical solution I have found is from this website. http://www.audiocostruzioni.com/a_d/diffusori/musicante-marco-monovia/musicante.htm The author build a transmission line using an internal resonating chamber which is not ported to outside and acts as an absorber chamber at a particular frequency which would otherwise cause a peak in the response. It would be usefull to reduce 100Hz peak allowing me to use a higher xover point but not to lower the bottom end. If you mean to port the rear chamber to the unused chamber and then port it to outside (series chambers) I don't know how it will behave and how long the outside port must be if i need to tune it below 40Hz. I was only able to model a rear vented chamber in hornresp adding the unused chamber to actual rear chamber by removing the horizontal panel and tuning a port between 35/40Hz. This seems to extend the bottom end but displacement at 40Hz is still above 8mm (~11mm peak) without the highpass filter and group delay reaches 40ms at the tuning frequency (and I still don't know if such delay is a problem or not). Maybe the port helps reducing temperature. Adding a 40/45Hz high pass filter as you suggested makes me worried about decreased output level at 40Hz (which in dub music is frequently used). I'm a bit lost . |
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Wrek0ne
Young Croc Joined: 10 February 2011 Location: Cambridge Status: Offline Points: 749 |
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Its quite easy to understand. It has four tuned ports - or resonators / resonant chambers as Rog has called them. A shared rear chamber for the 2 * 18" housing that is also seen as another resonant chamber equalling 'five resonant chambers' The drivers fire into a horn and share the final part of the horn path with each other. Its made out of wood and it has speakers inside it, there is no wizardry involved. In fact it shares many properties that this guys design does. Just with different positioning for the ports. |
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Poll this!
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drbis84
New Member Joined: 07 March 2012 Status: Offline Points: 7 |
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Hi Wrek0ne,
thank you for your reply. the fact is that I think Stasys is not just a simple ported horn. It has series chambers and I'm not expert with the design. The only thing I obtained with simulations of series chambers is higher group delay. :( I'm just a newbie so it may be I'm totally wrong. If the design was made using just one bigger chamber instead of dividing it in 5, would not get the same result, am I right? It is not magic in my opinion too but it is not so easy to understand. Anyway this not the puprose of my thread. I want to know if my desing is good as it is in performance side or it can be improved in some way. I don't want to take care about space lost for the moment. Thanks again! :) |
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