B&C 15DS115

[Pieter1267]

I make my case designs with a slightly older version of SketchUp Make, but that's after I've already done the case simulations, so I already know the parameters I have to keep to with the case. Prototypes are then needed for the detailed work.

A housing design then looks like this, for example:

View attachment 451415


In real life like this:

View attachment 451414


Or here, a small subwoofer:

View attachment 451407


Two of them receive their drivers:

View attachment 451425


Without a little school maths, of course, you won't get any further, e.g. you should already know how to calculate a volume.

That looks like 50 years away from anything ill ever be able to make. It looks amazing!

Can you figure out something like those sub cabinets for my current project? Subbox makes vent on the side like everybody else, but i like the at the bottom. I can give the calculated numbers but no way how to make it visible.

 

[Heinrich]

I make my case designs with ...

Don't know anything about designer software. I use pencil and paper. All other appears to me as far too compcated for the task.

Without a little school maths, of course, you won't get any further, e.g. you should already know how to calculate a volume.

What about the performance simulation? I'm currently playing around with a 12" bass/mid speaker.

WinISD starts with "boom box" alignment picked from a table, then increasing volume by hand doubling every step (pink curves). Then lowering the tuning to 25Hz (blue) and finally adding filters for equalization and low cut, as to protect against overexcursion (orange). The slight tilt towards bass is perfectly intended as to accomplish room gain (measured in my home).

The maximum volume in all cases is limited by the available power of just 50 (fifty) watts, while the final (orange) uses the Xmax to a good degree.

I personally think that 100dB single tone ~ 120dB pink noise (depends on driver, here it works) with just 50Watts insn't too shabby. It's worth the volume of 70liters. The bass/mid is accomplished by a reknown horn/driver at x/over of 1kHz.

That's what WinISD is about. I don't wet my pants about it, but it is well done and, for me, it was usable at an instance. I could discuss other crucial limitations like air speed in the port and so forth, but it ain't actially help, I'm afraid.

 

[MAB]

That looks like 50 years away from anything ill ever be able to make. It looks amazing!

Can you figure out something like those sub cabinets for my current project? Subbox makes vent on the side like everybody else, but i like the at the bottom. I can give the calculated numbers but no way how to make it visible.

Like this? I think with determination and perhaps a bit of help, this is achievable.

This is actually a flat-pack kit for a 15" sub.

15-Inch Cube, Roundover Series, Flat Pack (Single Unit) Shipping Included

MartySubs by GSG(TM) offer the best performance at the best price, anywhere. Check out our DIY flat packs as well as our finished enclosures. On sale now.

shop.gsgad.com

They recommend a LaVoce 15" driver. Other drivers can be used. Some will work better than others. The cabinet looks extremely overbuilt, not a bad thing, but might be in the land of diminishing returns and quite heavy to move. I haven't built this, but it looks pretty good when the woofer's published TS parameters are loaded into a box simulation with the approximate dimensions as the product claims.

If this is of a style that you like, and something similar available in your region, would this be an option? You could certainly use this box volume and port tuning to investigate other woofers. It might be a good starting point since it looks like a straightforward assembly. You still need some care when gluing and clamping a big assembly like this.

 

[Azrael]

Seems that they're using SketchUp too :

 

[Pieter1267]

Like this? I think with determination and perhaps a bit of help, this is achievable.
View attachment 451477
This is actually a flat-pack kit for a 15" sub.

15-Inch Cube, Roundover Series, Flat Pack (Single Unit) Shipping Included

MartySubs by GSG(TM) offer the best performance at the best price, anywhere. Check out our DIY flat packs as well as our finished enclosures. On sale now.

shop.gsgad.com

They recommend a LaVoce 15" driver. Other drivers can be used. Some will work better than others. The cabinet looks extremely overbuilt, not a bad thing, but might be in the land of diminishing returns and quite heavy to move. I haven't built this, but it looks pretty good when the woofer's published TS parameters are loaded into a box simulation with the approximate dimensions as the product claims.

If this is of a style that you like, and something similar available in your region, would this be an option? You could certainly use this box volume and port tuning to investigate other woofers. It might be a good starting point since it looks like a straightforward assembly. You still need some care when gluing and clamping a big assembly like this.

GSG is American. With Current USA > mainland Europe tarifs that will be a $1700 flatpack. But maybe good starting point. Im gonna ask the wife to see if she still knows autocad or sketchy from her Ikea days.But then she'll need stuff in return. Hmmm.

Edit: ive learned more mathematics. Port end correction is either .7 or 2.2. Vituixcad uses 2.2 while winisd uses the scoustic .7. Ditto subbox. 2.2 is a little less accurate but would still work. So i can use the subbox calculation and just use the shorter 2.2 instead of the much longer folded subbox design for the same freq tuning.

And with the subbox solution: if i just keep the gross volume at same number, i can change that design to the gsg or @Azrael ?

Does anyone try adjustable port, to see if higher tuning sounds better?

I love those flares. Ive seen them in some ports. Is there any advantage in a port for such?

 

[Heinrich]

GSG is American. With Current USA > mainland Europe tarifs that will be a $1700 flatpack. But maybe good starting point. Im gonna ask the wife to see if she still knows autocad or sketchy from her Ikea days. ...

Pencil on paper. It is called DIY because of doing it yourself. It may sound silly, but only so, because it is the very foundation of the concept. You've got one choice from three opportunities


- buy ready made a closed sub from the usual suspects, in particular do not at all care about technicalities, decide by the resulting acoustic data alone, which will be hard enough because it seems your expectations are a bit fuzzy (which is utterly o/k) and need translation from "hifi talk" to "tech talk"

- up-use the stuff you already have in taking, finally, advantage of equalization offered by your nice amp, get into measuring at least the room integration plus, let us know what main speakers you have and how you managed to set up the x/over, which is crucial, so much so that I'm tempted to get a bit frustrated why people here never mentioned it

- leave it alone, because the learning curve may be steep, but in using ChatGPT coming from other forums with lots of hifi-talking you led yourself so much astray, that coming back may be way harder than it would have been to take the right first steps to begin with, too much widely distributed, basically wrong ideas about actually irrelevant things, ignoring the basics - to be very clear, not your fault; but how could we possibly rectify all this over the internet remotely? No offense!

Edit: ive learned more mathematics. Port end correction is either .7 or 2.2. Vituixcad ...

O/k, I'll take that. The real mathematics is, that the end correction is rarely important, especially with a port as long as would fit into the enclosure. You know that inaccuracies of portlength are insignificant until the may reach 10% or so? What I told you was that *mathematically* a box is a filter, and filters are a mathematical 'group', so you can easily combine the physical properties of a box with electronic and digital filters to address a target response - that you might define, not ChatGPT or buddies from elsewhere.

And with the subbox solution: if i just keep the gross volume at same number, ... I love those flares. Ive seen them in some ports. Is there any advantage in a port for such?

As I said, such questions I can answer. But let us know, if you are going to dive deeper into the DIY, and, in case or not, what are the main speakers, and how the x/over to the existing subs was done. And, not the least, but ultimatively foremost, what were the measurements taken in order to achive the result?

 

[Pieter1267]

Pencil on paper. It is called DIY because of doing it yourself. It may sound silly, but only so, because it is the very foundation of the concept. You've got one choice from three opportunities


- buy ready made a closed sub from the usual suspects, in particular do not at all care about technicalities, decide by the resulting acoustic data alone, which will be hard enough because it seems your expectations are a bit fuzzy (which is utterly o/k) and need translation from "hifi talk" to "tech talk"

- up-use the stuff you already have in taking, finally, advantage of equalization offered by your nice amp, get into measuring at least the room integration plus, let us know what main speakers you have and how you managed to set up the x/over, which is crucial, so much so that I'm tempted to get a bit frustrated why people here never mentioned it

- leave it alone, because the learning curve may be steep, but in using ChatGPT coming from other forums with lots of hifi-talking you led yourself so much astray, that coming back may be way harder than it would have been to take the right first steps to begin with, too much widely distributed, basically wrong ideas about actually irrelevant things, ignoring the basics - to be very clear, not your fault; but how could we possibly rectify all this over the internet remotely? No offense!


O/k, I'll take that. The real mathematics is, that the end correction is rarely important, especially with a port as long as would fit into the enclosure. You know that inaccuracies of portlength are insignificant until the may reach 10% or so? What I told you was that *mathematically* a box is a filter, and filters are a mathematical 'group', so you can easily combine the physical properties of a box with electronic and digital filters to address a target response - that you might define, not ChatGPT or buddies from elsewhere.


As I said, such questions I can answer. But let us know, if you are going to dive deeper into the DIY, and, in case or not, what are the main speakers, and how the x/over to the existing subs was done. And, not the least, but ultimatively foremost, what were the measurements taken in order to achive the result?

Those are only valid if other solutions than changing driver are option. But its not. I decided i want to try a different driver and b. A different concept (ported vs sealed). Mainly because i feel the daytons get a bit into trouble above 60hz and esoecially above 80 and 90.

Ive been on this forum for about a year, extensively talking about my setup. Its changed, mainly the main speakers went through some iteration but atm its Revel F208. The are momentarily driven bi amped (crown xls 1502-quad606mki). Getting fed by channel 1,2 from minidsp ddrc24 downgraded to 2x4hd for full use MSO filters. MSO on input and minidsp channel 3 and 4. The xo is made in the mso, 95hz 24db buttersworth. I tried LR but Harbottle advisee buttersworth. The mains XO 110hz 24db buttersworth. I also implemented hpf at 25, 6db. I have a preset for full natural F208 without subs. Also one on 73xo and one preset with both xo at 100. Minidspchannel 3 and 4 into behringer6000dsp in stereo mode andcdsp off. However both channels are fed L+R in minidsp config.

Minidsp is fed analogue by quad34. I love the tone control of that old quad. I love Quad, period. Source mainly dragonfly usb plus isolator (also on usb to minidsp) from pc. Mostly spotify or flac etc. Also cd player. I have REW and know how to use it with umik1. Also have mso and know my way around it. I have tried several Dirac but its nice it also takes away too much character of the F208s. They are in 4x4 room, treated with curtains, sound absorb walls ceiling and carpet. Drywall in middle and low ceiling make it limited.

Im also wheelchair bound disabled - i cant walk or stand or use my legs so im severly limited in DIY. I managed to glue the dayton diy packet myself but specific wood cutting will not be possible. I have friends neighbours who will help getting and cutting wood for new sub cabinets. Putting in new driver, the weight, i will also deff need help with that.

I have a dog, golden retriever and everybody thinks she helps me but im her servant for daily food, walks to seek delicious cat end products etc. I drive her to a pension once a week so she can play with other canines.

Im an ex club dj, did that for 15 good years on various systems. I kind of know what kind of sound im looking for and after playing with many many subwoofer systems im kind of convinced i need a different kind than the one i have now. Also, like many here, addicted to always look to improve. I might add atc scm 11 or 19 later but the F208 are end game. Very difficult to find in EU. Finally found one near Koln. That said, i might upgrade to 228Be but in a few years. Im very lucky with what i have and i can spend on stuff i like.

 

[Heinrich]

Those are only valid if other solutions than changing driver are option. But its not. I decided i want to try a different driver and b. A different concept ...

As said, to ventilate an eclosure or not isn't a concept change, if you look at the speakers as a filter. Especially when going pro/ the driver's manufacturer expects his product to be accomplished with electronic/digital filters. That is why you cannot achieve best results with a naked driver/enclosure combo.

It came out that optimizing for T/S parameters isn't as effective as tuning the design for most linear x/max & power; quite simple after the fact. They aren't fools.

Getting fed by channel 1,2 from minidsp ddrc24 downgraded to 2x4hd for full use MSO filters. MSO on input and minidsp channel 3 and 4. The xo is made in the mso, 95hz 24db buttersworth. I tried LR but Harbottle advisee buttersworth. The mains XO 110hz 24db buttersworth. I also implemented hpf at 25, 6db. I have a preset for full natural F208 without subs. Also one on 73xo and one preset with both xo at 100. Minidspchannel 3 and 4 into behringer6000dsp in stereo mode andcdsp off. However both channels are fed L+R in minidsp config.

You do not mention an equalizer for room modes and all. I myself started DIY without measurement facilities. Now you know how darn old I might be Today I feel DIY is boring, except for experimental designs that prove one or the other concept (speaking of more fundamental issues;-). Still I won't miss my measurment gear. Can't listen to my top grade commecial speakers w/o additional, personal adaption.

Sorry that I can't recommend a find for your quest.

ps: don't worry, I hate the woodworking part myself - all that dirt and imprecision, and fail ...

 

[Pieter1267]

guys im contemplating making port area smaller. Il pay a bit in chuffing problems but my tuning is now at about 1000watt input with 126dB and i will never ever get near that. So I figured: can i go down from 440cm2 to say 340? Then the air velocity starts to become problematic at around 700 watt but still a figure i will not get near. In the end you build a sub optimal cabinet but can it be done with penalties below 600 watt?

Also: is it better to put another baffle plate on top of the front plate of that subbox pro design?

 

[Heinrich]

guys im contemplating making port area smaller. Il pay a bit in chuffing problems but my tuning is now at about 1000watt input with 126dB and i will never ever get near that. So I figured: can i go down from 440cm2 to say 340? Then the air velocity starts to become problematic at around 700 watt but still a figure i will not get near. In the end you build a sub optimal cabinet but can it be done with penalties below 600 watt?

Also: is it better to put another baffle plate on top of the front plate of that subbox pro design?

ChatGPT says, that the baffle's deflection is driven by the inward pressure. I asked for a calculation, but it circumvented it by stating an error on its side, and corrected by a factor of 48 (no, it wasn't the famous '42'). Oh, it's inertia actually. Then I asked for the frequency of a claimed resonance, and it was "calculated" to be 38,4Hz - of the baffle in itself, go figure! With that my daily budget was exhausted. Fun over. A three digit number derived from what model exacly, it not knowing anything specifically (driver weight, cone weight etc)?

I've got two accelerometers, and I investigated enclosure flexing a lot. I've never seen something around that lines. Ah, first ChatGPT stated a flex of 0,3mm in a 40x60cm^2 baffle. But it forgot, somehow, the driver cutout, and, admitted on request, the driver itself was missing, not to mention the aluminium chassis. Then, on asking forward, the contribution of the chassis to stiffness was dumped, argueing with a silly analogy. It got a bit stubborn (lazy?) then.

Yes, please double the front baffle, whatever it takes ... no? The higher the effort, the better the sound?

In regard to your port area, isn't it half the cone's area already, and you still expect chuffing, but with what shape of the end pieces, speaking of aerodynamics? What do you think, will you get there with success, or would it be better to withstand the "gear acquisition syndrom"? It's 2k in whatever currency, a nice vacation w/ significant other on the Canaries? I mean, you didn't push your existing gear into optimum, lots to play around still. I grant that!

alternative, maybe, to boring Canaries and circumstances => https://www.audiosciencereview.com/forum/index.php?threads/rythmik-l12-subwoofer-review.12140/

 

[3ll3d00d]

Design for your actual use

ie how loud do you really need it to go? Size the amplifier and the port to achieve that (remembering that if you add a high pass filter to protect the driver that this will naturally reduce the port output a touch if it's in the right place).

Finally use hornresp with it's complex le model to get a more accurate simulation.

 

[Pieter1267]

Design for your actual use

ie how loud do you really need it to go? Size the amplifier and the port to achieve that (remembering that if you add a high pass filter to protect the driver that this will naturally reduce the port output a touch if it's in the right place).

Finally use hornresp with it's complex le model to get a more accurate simulation.

Yup. Im gonna put the brakes on the whole project and do some more reading and studying. And hornresp and Vituixcad.

 

[Pieter1267]

Small update. Went back to make basic 1m measurements of all speakers. Turns out im a failure for building diy flatpacks, as sub 2 had a mechanical failure. Turns out the speakon terminal wasnt sealed properly and i had a leak. This became apparent when testing on chatgpt suggestions. Then he suggest to look for anomalies on the gd graph in rew. Bingo. Big big spike at the area that gave a big unexplained null.

Fixed it, going to do more testing tomorrow. Because the mains show suck out between 110 and 135, we are testing putting the subs at 125 low pass and the mains at 140 high pass. It actually sounded quite amazing. Also decided to switch back to stereo input as the room is so small L+R summation is just too much.

Also made Vituixcad working. But im eager to see the results with a fixed sub cabinet. Lesson learned: stop doing hasty jobs 30 minutes before you take wife out for diner, and 2: test diy cabinets thoroughly after putting together. Wasnt all bad.

And i like working with chatgpt. Its fun.

 

[Heinrich]

Small update. Went back to make basic 1m measurements of all speakers. ... sub 2 had a mechanical failure. Turns out the speakon terminal wasnt sealed properly and i had a leak. This became apparent when testing on chatgpt suggestions. ...

And i like working with chatgpt. Its fun.

@Pieter1267 , it was my honor and pleasure to recommend some measurements to be taken. I'm real.

 

[Pieter1267]

Ok here is an update.

I decided to do some new basic measurements on all speakers, not just MLP but also on axis 30cm and 1meter. Some experiments with room and placements and such.

The findings are that the Revel main speakers have some room crated suck out between 110 and 150. because room is small and f208s are big i cant do anything about that. The low frequencies also seem to get less below 100hz. Therefore I decided to increase XO with the Daytons to about 125 and see how that goes. The mains at 140. it sounded better but the nul around 50 remained. On closer inspection it turns out I made a mistake assembling the diy sealed cabinet of sub number 2. A huge spike at GD gave it away. Turns out the speakon terminal was having a leak. I fixed it today and now both sub perform quite similar. for refrence: both sub cabs are 49x49x51cm (122 liter sealed)

I had to add 2 all pass filters on both subs and one on the mains and after some levelling, now they seem to be happy.

For now im not sure how to go further. I think im quite happy with the Daytons below 50 but above it remains a bit wooly. I think ill embrace GSG's Kevins suggestion to simply keep teh Daytons and add a nice 10 or 12" for more mid bass kick, also perhaps an even higher xo. Anyway, the ultimaxes seem to end sounding good around 130. I also decided to put them in stereo since that made levelling easier.

ChatGPt was extremely helpfull with figuring stuff out with REW. I also somehow made Vituixcad work. Still, a lot of parameters are abracadabra.

Chatgpt advised to have the follow T/S parameters for a 12' replacement
sealed, as small as posisble box (between 25-50 liters ideally)
QTS 0.2 - 0.35
Fs <55
mms <80
BI >15
Xmax min 5 or 6mm
Sd >500cm2
SPL 96>
Vas 40-100
Le <1.5 mH

Is this kind of ballpark? Any other suggestions or corrections?

Atm I have a short list of

Oberon 12NB450
Beyma 12P80Fe/v2 (unavailable at tlhp)
Faitalpro 12FH500
RCF LF 12G301
18sound 12W750
B&C 12NDL76

the max SPL that im looking for is about 110-115 but between 107 and 110 is fine too. Here are some graphs and measurements. MMM and MLP. Mains only and subs only.

MLP full range before all pass filters corrected phasing issues

fixed with all pass, mmm measurement

wider perspective

main right

main left

older ultimax, sub 1

sub 2, the ultimax II, leaky cab

sub 2 cab after fix, with xo125hz

 

[Heinrich]

On chatgpt, no, it is rubbish. It is a Large Language Model, LLM, as was already told by many several times. It optimizes the language to sound human, not the reasoning behind its talking. To showcase the difference one only needs to be an expert in a particular field. Could be tech/, could be arts, whatever. You easily get into sheer bullshit mode; please excuse the rude wording, but here it is, alas, appropriate.

I‘m a bit frustrated, that you didn‘t acknowledge my contribution to problem solving. If you give all credit to LLM alone, so be it.

 

[Pieter1267]

On chatgpt, no, it is rubbish. It is a Large Language Model, LLM, as was already told by many several times. It optimizes the language to sound human, not the reasoning behind its talking. To showcase the difference one only needs to be an expert in a particular field. Could be tech/, could be arts, whatever. You easily get into sheer bullshit mode; please excuse the rude wording, but here it is, alas, appropriate.

I‘m a bit frustrated, that you didn‘t acknowledge my contribution to problem solving. If you give all credit to LLM alone, so be it.

Im sorry Heinrich but your English is a bit difficult to follow sometimes. Many suggested taking more measures. If you did too then i must have overlooked and i apologise.

I was discussing why the null came up with chatgpt. Then i suggested could it be a mechanical failure since i put the package together in about 40 minutes before i had a dinnerdate with my wife.

Immediatly chatgpt suggested to manually push the woofer and listen or look for gaps. I kept one hand near terminal whilst pushing and bingo, air stream felt. Closer inspection showed i missed closing a small gap.All these months i was experimenting with a leaky sub cabinet.

Going back in rew, chatgpt suggested to check groupdelay for spikes. That confirmed it 100%.

After the fix, again i did a 1m measure to confirm fix. Again a spike showed in gd. Chatgpt then helped and showed me to go even deeper and check excess delay and minimum phase. I went through about 6 pages i cant even tell but in the end, we came upon a graph that showed it was bad measurement, not the sub.

Chatgpt then suggested to take 30cm from cone measurement. This sgain helped and confirmed it was fixed.

I find that amazing and chatgpt was instrumental in helping out. The manual pushing of woofer was pivotal in discovery. No measure, not with my limited rew knowledge, would have digged that up. Nobody told me to compare and check gd graphs for mech faults. Neither did you. That was chatgpt.

I also let it make minidsp files which he made a lot of errors but if you just keep it as text help, its fantastic.