Hello,
I would like to dip my toes in transmission line design. I have a Dayton Audio SD315A-88 I would put in t-line (+-3.8m, 200L in total with a ratio 70L/130L left and right to the speaker). Is this somewhat in the ballpark with your experience?
The sub will be quite big so I want to make the sub downward firing so that I can subtly put it in a corner, paint it the same color of the wall and hope my wife doesn't see it before she hears it 😀
On a serious note: Most t-line's you see are flatpack style (like a big lunchbox with the speaker on the long side). I don't find any downward firing ones. Is there any reason to it? Is downward firing not the way to go?
I like well defined quality bass but I don't seem to like it when there's line-of-sight between the speaker itself and my ears. It feels to direct, pounding my eardrums and less of an ambiance. I find it difficult to describe..I hope you understand what I mean?
Kind regards,
R
I would like to dip my toes in transmission line design. I have a Dayton Audio SD315A-88 I would put in t-line (+-3.8m, 200L in total with a ratio 70L/130L left and right to the speaker). Is this somewhat in the ballpark with your experience?
The sub will be quite big so I want to make the sub downward firing so that I can subtly put it in a corner, paint it the same color of the wall and hope my wife doesn't see it before she hears it 😀
On a serious note: Most t-line's you see are flatpack style (like a big lunchbox with the speaker on the long side). I don't find any downward firing ones. Is there any reason to it? Is downward firing not the way to go?
I like well defined quality bass but I don't seem to like it when there's line-of-sight between the speaker itself and my ears. It feels to direct, pounding my eardrums and less of an ambiance. I find it difficult to describe..I hope you understand what I mean?
Kind regards,
R
Greets!
First things first; while down-firing is fairly common, based on published specs this driver will sag too much: Resources - Woofer Mount Up Down
No experience with this woofer per se, but decades worth specs wise in general; and yes, understand what you mean performance wise. Per my avatar, I mostly prefer an 'in-your-face' prosound type [live] performance, though for acoustic [un-amplified], definitely prefer a more life-like 'washing over'/'engulfing' bass presence and let its upper harmonics provide the [mid] bass, lower mids 'is it live or is it Memorex' bass 'fullness'.
That said, for such performance, a woofer ideally needs to be limited to < 80 Hz down-firing and < 120 Hz if not integrated into a multi-way.
With a ~34400/pi/4.95 = ~2212 Hz VC coil limited pistonic power response, this 'woofer' is obviously designed for multi-way apps, so before going further, how do you want to proceed?
GM
First things first; while down-firing is fairly common, based on published specs this driver will sag too much: Resources - Woofer Mount Up Down
No experience with this woofer per se, but decades worth specs wise in general; and yes, understand what you mean performance wise. Per my avatar, I mostly prefer an 'in-your-face' prosound type [live] performance, though for acoustic [un-amplified], definitely prefer a more life-like 'washing over'/'engulfing' bass presence and let its upper harmonics provide the [mid] bass, lower mids 'is it live or is it Memorex' bass 'fullness'.
That said, for such performance, a woofer ideally needs to be limited to < 80 Hz down-firing and < 120 Hz if not integrated into a multi-way.
With a ~34400/pi/4.95 = ~2212 Hz VC coil limited pistonic power response, this 'woofer' is obviously designed for multi-way apps, so before going further, how do you want to proceed?
GM
Thank you for that link about downward firing subwoofers! I didn't even know there was a way to tell by calculation of a few specs 🙂
34400/pi/4.95 = ~2212 Hz: Google doesn't help a bit on explaining pistonic power response (or at least the formula you used). I guess the 4.95 is the VC diameter in cm. I also guess the 344 is close to 343 m/s aka speed of sound in cm/s? Then how do they relate?
Do you conclude that this subwoofer is actually just a big woofer and not suited for a subwoofer application?
I think I would also be able to make it into a wall-firing box so that the sound is dispersed along the wall instead of the floor? Or do you have another option?
I thank you for your help!
34400/pi/4.95 = ~2212 Hz: Google doesn't help a bit on explaining pistonic power response (or at least the formula you used). I guess the 4.95 is the VC diameter in cm. I also guess the 344 is close to 343 m/s aka speed of sound in cm/s? Then how do they relate?
Do you conclude that this subwoofer is actually just a big woofer and not suited for a subwoofer application?
I think I would also be able to make it into a wall-firing box so that the sound is dispersed along the wall instead of the floor? Or do you have another option?
I thank you for your help!
The SD315-88 is billed as a "subwoofer" driver by Dayton audio. Xmax is a little low for a modern-day subwoofer though (7mm). The recommendation is for a 2 cu.ft. box tuned to 38 Hz. I'd model the impact of semi-inductance on the response curve and probably opt for a EBS type OD-TL arrangement 30 Hz Fb box size around 3 cu.ft. maximum. Should easily get down to 30 Hz when room gain is taken into effect. I wouldn't use an Fb lower than that with that driver, considering the limited Xmax. Even at a 30 Hz Fb, output will be displacement limited in its passband. Opting for a 40 Hz Fb will improve power-handling a bit.
200L is way oversized for a woofer of those specs.
200L is way oversized for a woofer of those specs.
You're welcome!
Correct, I use 344 m/s since a lot of folks here use Hornresp. Where I live it calcs ~344.424 m/s 😉.
Well, 'sound' is round, so a round radiator with a round VC that equates to ~2212 Hz pumps out round pressure waves to ~ this frequency and above this point they travel in/on the diaphragm's surface based on its material 'speed' [TL modes BW] and at some point the WLs are so high/'weak' they just pop off wherever they can 'break-up modes BW].
In short, this is the technically correct upper XO limit to another round radiator, though ideally would be much lower to get a good off axis power response match-up.
Again, this is a wide range woofer designed for multi-ways, i.e. from the days when recordings didn't go below 42 Hz 'flat' and as a 'sub' woofer for the few recordings that went down to a rolling off 27.5 - 32 Hz. Actual subwoofers for the few RTR tapes available were typically huge standalone 'two note' [2 octave] devices.
Of course it can be used as just a 'sub' woofer since it does have a low enough Fs for most music, but is it also for lower and/or more 'intensive' special effects and using a [lossy/rolled off] TL loading with 'only' 7 mm Xmax, will it play loud/'strong' enough for you is the current 'burning' questions. 😉
Yes, you can wall load it assuming it's rigid/massive enough like a floor. Angled down into a corner 'V' is best overall for 'sub' woofer loading', but complicates the box woodworking.
Need full room details/dims to speculate further.
GM
Correct, I use 344 m/s since a lot of folks here use Hornresp. Where I live it calcs ~344.424 m/s 😉.
Well, 'sound' is round, so a round radiator with a round VC that equates to ~2212 Hz pumps out round pressure waves to ~ this frequency and above this point they travel in/on the diaphragm's surface based on its material 'speed' [TL modes BW] and at some point the WLs are so high/'weak' they just pop off wherever they can 'break-up modes BW].
In short, this is the technically correct upper XO limit to another round radiator, though ideally would be much lower to get a good off axis power response match-up.
Again, this is a wide range woofer designed for multi-ways, i.e. from the days when recordings didn't go below 42 Hz 'flat' and as a 'sub' woofer for the few recordings that went down to a rolling off 27.5 - 32 Hz. Actual subwoofers for the few RTR tapes available were typically huge standalone 'two note' [2 octave] devices.
Of course it can be used as just a 'sub' woofer since it does have a low enough Fs for most music, but is it also for lower and/or more 'intensive' special effects and using a [lossy/rolled off] TL loading with 'only' 7 mm Xmax, will it play loud/'strong' enough for you is the current 'burning' questions. 😉
Yes, you can wall load it assuming it's rigid/massive enough like a floor. Angled down into a corner 'V' is best overall for 'sub' woofer loading', but complicates the box woodworking.
Need full room details/dims to speculate further.
GM
Maybe I should describe the complete system I have in my head? I bought the RS180-8 and want to pair it with a SB accoustics SB19ST tweeter.
The single Subwoofer would only play up to 80-100Hz range.
I will use the Wondom Adau 1701 active crossover.
I listen to all sorts of music: from blues to chillstep, rock and metal to lounge/house music. Only thing I don't listen to seems to be pop.
From time to time I like a good movie but I'm not looking to recreate the big movie theatre sound at home.
I don't really need window shattering bass. I just want the void below 80Hz (in blues, rock, metal) to be filled and just the extra oumpf when watching a movie or listening to electronic music. I'm not the type of guy that is looking for maximum bass output.
The room it will stand in is pretty much a square 8x4m with 2.8m ceilings. The long walls are interupted by a closed staircase on one side and a fireplace on the other side. The sub can be placed everywhere along the long (8m) walls.
The 200l box I calculated is because I was looking for a nice stretch 80Hz down to 25-30Hz. I'm not looking for the highest volume here so I accepted some accoustical power loss. I put a graph from Hornresp in attachment. I also uploaded a Diaphragm displacement graph. Is that what you are talking about when looking at the XMax Brian?
When given the speaker I have, how would you go next GM? Do you follow Brian saying I should only tune it to around 35-40Hz?
And Brian: Looking at my Hornresp input parameters..Would you start by decreasing the length of the TL or reduce the S2/S3?
I really do appreciate your help guys!
The single Subwoofer would only play up to 80-100Hz range.
I will use the Wondom Adau 1701 active crossover.
I listen to all sorts of music: from blues to chillstep, rock and metal to lounge/house music. Only thing I don't listen to seems to be pop.
From time to time I like a good movie but I'm not looking to recreate the big movie theatre sound at home.
I don't really need window shattering bass. I just want the void below 80Hz (in blues, rock, metal) to be filled and just the extra oumpf when watching a movie or listening to electronic music. I'm not the type of guy that is looking for maximum bass output.
The room it will stand in is pretty much a square 8x4m with 2.8m ceilings. The long walls are interupted by a closed staircase on one side and a fireplace on the other side. The sub can be placed everywhere along the long (8m) walls.
The 200l box I calculated is because I was looking for a nice stretch 80Hz down to 25-30Hz. I'm not looking for the highest volume here so I accepted some accoustical power loss. I put a graph from Hornresp in attachment. I also uploaded a Diaphragm displacement graph. Is that what you are talking about when looking at the XMax Brian?
When given the speaker I have, how would you go next GM? Do you follow Brian saying I should only tune it to around 35-40Hz?
And Brian: Looking at my Hornresp input parameters..Would you start by decreasing the length of the TL or reduce the S2/S3?
I really do appreciate your help guys!
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Well, you should have posted all this first 😉 as you seem to understand/accept the design's inherent performance limitations Brian and I were concerned about and see nothing wrong with your sim, so good luck with it and please let us know if it does indeed satisfy your performance goals.
FWIW, for low Qt drivers that dictate a long vent to tune low, I prefer to convert the box/long vent into an inverse tapered TQWT to get more TL pipe loading = a bit more acoustic power gain down low.
GM
FWIW, for low Qt drivers that dictate a long vent to tune low, I prefer to convert the box/long vent into an inverse tapered TQWT to get more TL pipe loading = a bit more acoustic power gain down low.
GM
A few things...
1. Change the setting from 0.5xPI to 2xPI, to produce results are more in line with other modelers will produce.
2. You can significantly reduce the size of the TL without giving up much performance by going for a tapered layout. Aim for a mouth that's no smaller than 1/3rd Sd, and a bit larger if possible. This will also shift the "null frequency" a bit higher, reducing the offset required to remove it. For an idea of a tapered TL layout that can work, check my "Boom Unit" build at the following link: The Subwoofer DIY Page v1.1 - Projects : The Boom Unit
3. Derive the semi-inductance parameters for the SD315 and include those in your Hornresp sim. The results may lead you to adjust your sim to get a smoother response at higher frequencies. More information here - The Subwoofer DIY Page - Semi-Inductance
4. Make sure all segments in your sim are set to PAR.
5. Always keep an eye on power-handling within your design passband. A good "figure of thumb" to go by is to ensure Xmax isn't exceeded within your designs passband if the driver is driven at half its rated power.
6. Good luck with your build. That particular driver has been on my list as one of the drivers I'd like to try in a build. Alas, I have too many subwoofers already 🙂.
1. Change the setting from 0.5xPI to 2xPI, to produce results are more in line with other modelers will produce.
2. You can significantly reduce the size of the TL without giving up much performance by going for a tapered layout. Aim for a mouth that's no smaller than 1/3rd Sd, and a bit larger if possible. This will also shift the "null frequency" a bit higher, reducing the offset required to remove it. For an idea of a tapered TL layout that can work, check my "Boom Unit" build at the following link: The Subwoofer DIY Page v1.1 - Projects : The Boom Unit
3. Derive the semi-inductance parameters for the SD315 and include those in your Hornresp sim. The results may lead you to adjust your sim to get a smoother response at higher frequencies. More information here - The Subwoofer DIY Page - Semi-Inductance
4. Make sure all segments in your sim are set to PAR.
5. Always keep an eye on power-handling within your design passband. A good "figure of thumb" to go by is to ensure Xmax isn't exceeded within your designs passband if the driver is driven at half its rated power.
6. Good luck with your build. That particular driver has been on my list as one of the drivers I'd like to try in a build. Alas, I have too many subwoofers already 🙂.
Does anyone find the ‘taper to exit’ shape (smaller at open end of pipe) to ever have a slight tendency to get dull or (-list of adjectives that are muddy, Slow, or bass reflex like potential issues?) and might even lag a bit? That’s a question, not a statement (currently). But if any of you’ve noticed the snappy sound of a good driver in a good Tapped pipe/horn vs in any other qw pipe generic shape and appropriate driver in it? Then that might not sound so inappropriate (even though it’s wrong and I use MLTL or similar for the lowest bass frequencies myself.(but curiously not the higher ones, they sound sharper if made through tapped or similar ??)imho and slow learning process of elimination/experimentation.
I can explain further but I don’t want to be rude or clog you’re thread up Reinhout🙂. apologies, (Tapped pipe verses a ‘normal’ pipe. Tapped can seem a little ‘energetic or even a slight tweak to the phase angles summed or impulse junk and that can of worms.
I can explain further but I don’t want to be rude or clog you’re thread up Reinhout🙂. apologies, (Tapped pipe verses a ‘normal’ pipe. Tapped can seem a little ‘energetic or even a slight tweak to the phase angles summed or impulse junk and that can of worms.
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Well there’s a reason for that. you actually know what you’re doing 😀 or at least you fake it pretty well. it’s not as easy without that advantage, lol. I’m catching up slowly ...
I need you to build an electrical impedance dumpster ?? so you can answer all my dumb questions about mine🙂
POC: roar or qw higher order in parallel or parallel-series maybe ? Something that’s tuned and vented off both sides seperate and then smashed together with a bit of intention.
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