Hi all
I was sent this way from another forum as someone here may be able to advise me if my project is worth it.
Basically I have two spare 8" kef sp1075 bass drivers and was wondering if I could utilise them in a box to use a subwoofer for my ht system.
I was told decent ht subs go as low as 20hz. These speaker's specs say they can go as low as 27fs and after playing with winisd for the first time I modelled 20hz at -4.5db in a 90l vented enc with two of these drivers in an isobaric config.
can someone take a look at the graph and tell me if this look right or if there is something I can change to improve the freq response please?
I was sent this way from another forum as someone here may be able to advise me if my project is worth it.
Basically I have two spare 8" kef sp1075 bass drivers and was wondering if I could utilise them in a box to use a subwoofer for my ht system.
I was told decent ht subs go as low as 20hz. These speaker's specs say they can go as low as 27fs and after playing with winisd for the first time I modelled 20hz at -4.5db in a 90l vented enc with two of these drivers in an isobaric config.
can someone take a look at the graph and tell me if this look right or if there is something I can change to improve the freq response please?
Attachments
They can be made into a sub, but it depends what your expectations are. They don't have the excursion and power robustness of modern sub drivers, not the ideal of parameters.
I think you will find that the perfromance of that sub will be disappointing, take a look at the power handling graph. You are trying to push it too far with too low tuning and too big box.
I think you will find that the perfromance of that sub will be disappointing, take a look at the power handling graph. You are trying to push it too far with too low tuning and too big box.
yes, I put in what I think are the excursion figures and now I see a power curve. it rises to max power at 20hz then dips before rising again. is this not good?
According to this, it's 3 mm Xmax, 10 mm Xlim: KEF B200G SP1075
Yes, the dip is showing you were it's exceeding Xmax in 2 pi [half] space, so add a couple of dB if up against a wall and a few more if in a corner. Technically, it would be more, but most rooms have pretty lossy construction.
GM
Yes, the dip is showing you were it's exceeding Xmax in 2 pi [half] space, so add a couple of dB if up against a wall and a few more if in a corner. Technically, it would be more, but most rooms have pretty lossy construction.
GM
Last edited:
Well, THX cinema reference is flat to 20 Hz IIRC, though some movies have significant output down below 10 Hz w/roll-off down to near Dc, so only large sealed sub systems can replicate these, not to mention some home's construction can't handle them at high SPL, so 'caveat emptor'.
If one ignores the LFE channel's output though, then tuning to a piano's 27.5 Hz will handle all but the largest pipe organ's BW, ergo normally all of a movie's or orchestra's basic soundtrack, so all things considered, making two separate subs tuned to ~27 Hz to get better overall positioning in room and a higher peak SPL where most of the action's 'slam'/'punch' is seems the way to go and later add a true sub-woofer system as budget permits to get the potentially construction damaging LFE explosions, low B organ pipe's, etc. effects. Note that you'll need a hi-pass to protect them, so make sure the amp has an adjustable one if your receiver doesn't.
FYI, you'll get a bit more accuracy, options with the newer WinISD 0.7.0.900: https://twitter.com/suurvisiiri/status/139665715740413952
GM
Last edited:
Hi thanks for the info that's very helpful.
I was looking at buying an off the shelf subwoofer but a lot of the ones within my budget had the same freq response range as these speakers so I was just wondering weather I could utilise these drivers to produce a similar sound.
I've attached the max power chart though i don't yet fully understand what i'm looking at.
so presuming I tune these at 25 or 27hz instead is that probably the best route?
I was looking at buying an off the shelf subwoofer but a lot of the ones within my budget had the same freq response range as these speakers so I was just wondering weather I could utilise these drivers to produce a similar sound.
I've attached the max power chart though i don't yet fully understand what i'm looking at.
so presuming I tune these at 25 or 27hz instead is that probably the best route?
Attachments
In general for speakers you can buy similar for the same or less than what it costs to make. Unless you have wood and power amps to hand, then it's not worth it in my opinion.
DIY audio is for fun more than money saving. It's only once you have made a ton of stuff and spent years learning that you can make good stuff that competes with stuff much more expensive.
DIY audio is for fun more than money saving. It's only once you have made a ton of stuff and spent years learning that you can make good stuff that competes with stuff much more expensive.
Totally agree.
I had these drivers spare so just thought i'd see if I could utilise them. Also have a couple of guys who are cabinet makers and would knock me up these boxes for beer tokens.
Whole reason for this project is to see if I can make something similar or better for not much cost. if not I could always sell the drivers and put the money towards an off the shelf subwoofer...but like you say...where's the fun in that! ;-)
been playing some more with winisd....if I go back to using one driver in a 120l vented enclosure I get almost max spl for this driver at 27hz?
im sure ive seen a kef enclosure with two of these drivers wasn't it the 105.4's? wonder what there stats were...
I had these drivers spare so just thought i'd see if I could utilise them. Also have a couple of guys who are cabinet makers and would knock me up these boxes for beer tokens.
Whole reason for this project is to see if I can make something similar or better for not much cost. if not I could always sell the drivers and put the money towards an off the shelf subwoofer...but like you say...where's the fun in that! ;-)
been playing some more with winisd....if I go back to using one driver in a 120l vented enclosure I get almost max spl for this driver at 27hz?
im sure ive seen a kef enclosure with two of these drivers wasn't it the 105.4's? wonder what there stats were...
As the KEF drivers are a bit sought after, I would flog them and buy some more suitable drivers then carry on with the project. You can probably buy a pair of JBL GTO804 drivers.
Do you realise how big a 120 litre box is? 😉
Do you realise how big a 120 litre box is? 😉
sorry just saw this...yes it is rather big lol and yes you make sense...ill prob end up going that way.
so if I ditch the idea of using these and flog them. what sub could I buy that would run off an av receiver such as the pioneer vsx924 105wrms @ 8ohms 150wrms @6ohms. don't mind building the enc myself
hey thankyou I was just about to give up on the idea but wow I have no idea what a lossless horn tappy is but the graphs certainly look good!
firstly thankyou for your time! having a quick google on the above. am i correct in thinking this a three section enclosure using both drivers in a series config? also what are the external dimensions of the cabinet?
that is some seriously good spl at that tuning!
firstly thankyou for your time! having a quick google on the above. am i correct in thinking this a three section enclosure using both drivers in a series config? also what are the external dimensions of the cabinet?
that is some seriously good spl at that tuning!
'am i correct in thinking this a three section enclosure using both drivers in a series config'
Hi avnewbee,
Correct.
Here is the requested ML-TL:
Quarter Wavelength Loudspeaker Design
b🙂
Attachments
Wow thankyou very much! Am I correct in thinking the freq is cut off at 25hz due to the excessive diaphram displacement? So not likely to hit 20hz?
The box looks easy enough to make but what it a local liner?
I think ill make two of these enclosures, especially as it seems I get more spl from this design with one driver and smaller enclosure though sacrificing 5hz bw. Which was prob asking too much from these low excursion 8" drivers anyhow.
Cant wait to build them now! Lol Thanks again, much appreciated. Will update thread with build progress.
The box looks easy enough to make but what it a local liner?
I think ill make two of these enclosures, especially as it seems I get more spl from this design with one driver and smaller enclosure though sacrificing 5hz bw. Which was prob asking too much from these low excursion 8" drivers anyhow.
Cant wait to build them now! Lol Thanks again, much appreciated. Will update thread with build progress.
Hi,
Yes: xmax is only 3mm Peak!, 20 Hz is too low for one Driver to handle.
A Local Liner Damping is determined by a one Axis(Dimension) Pressure Differential that cause Absorption opposed to a Non Local Liner that at least operates using 2 Dimensions.
b🙂
PS: Your Room will add Boundary Gain, i.e. No need to chase 20 Hz!
Attachments
- Status
- Not open for further replies.