I run RS225 in approx 25 litres. I did port them for added LF extension but I do prefer sealed. I was thinking about going back to sealed and adding a second RS225. Will halve the excursion.
But then got to thinking about doing an LT on them. RS225 in 25litres Sims as FC = 69hz and q = 0.68 for 1 woofer and 0.86 for X2 RS225. Haven't measured but I think it was about there.
I plugged this in an LT spreadsheet. The target Q=1 helps with the F6/F10. I think I would aim for a Q of 0.6 or so normally sealed. Or atleast I like the sound of that. Does this add much GD?
Have kept it quite modest for now as don't want the gain to be too high. Probably will run them on a JLE 3255 but maybe needs more power. Small ish UK living room so SPL required isn't massive.
The LT obviously asks a lot of the power demands and excursion capabilities. If I add a given LT to one woofer, what happens if I add a second woofer? The original Fsc raises. Does the 2nd driver help in the excursion? Does it make the power demands worse?
Thanks
But then got to thinking about doing an LT on them. RS225 in 25litres Sims as FC = 69hz and q = 0.68 for 1 woofer and 0.86 for X2 RS225. Haven't measured but I think it was about there.
I plugged this in an LT spreadsheet. The target Q=1 helps with the F6/F10. I think I would aim for a Q of 0.6 or so normally sealed. Or atleast I like the sound of that. Does this add much GD?
Have kept it quite modest for now as don't want the gain to be too high. Probably will run them on a JLE 3255 but maybe needs more power. Small ish UK living room so SPL required isn't massive.
The LT obviously asks a lot of the power demands and excursion capabilities. If I add a given LT to one woofer, what happens if I add a second woofer? The original Fsc raises. Does the 2nd driver help in the excursion? Does it make the power demands worse?
Thanks
Attachments
I would try putting the driver details into WinISD and then add the transform in the filter section and see what the excursion and SPL is at a sensible amp power (say 50W). You can download WinISD formatted driver data from the loudspeakerdatabase site and add them to the directory with all of the driver in it. I suspect with that transform you will run out of excursion pretty quickly at the low end.
With 2 drivers in 28litres and a transform of 45hz and Q=0.707 I get just under Xmax at 25watts which would give me 93db at my listening distance.
You can also select the "Amplifier apparent load power (VA)" to see how much power your amps will actually need with the LT in place.
lets turn our bass knob to +6dB.
did the woofer fly out the chassis? did the amp blow?
no?
ok then, you can use ltx.
I recommend to not simply use a LT filter, as it will amplify all frequencies below boost down to DC. Add a high-pass filter to protect the woofer from signals at frequencies below its usable bandwidth. You can use a high-pass filter to do both, by tuning it to give a peaking response where you need the LT effect.
https://sound-au.com/project197.htm
https://sound-au.com/project197.htm
Thanks for that. I was thinking of ordering a Rod Elliott LT PCB but I don't think he does a board for the project you link to. Do you know of any?
Many moons ago I built something similar, with DC speaker protection onboard. I recently discovered two blank PCBs for it but, sadly, I have lost the schematics.
It's not clear what gave you the impression of an "undefined conjugate". No reason for it to be undefined. Back when I designed the circuit I had built, I was using Speaker Workshop, an early freeware loudspeaker measurement and design software. I was able to define a high-pass filter as target curve and tune the filter to achieve the desired final response.
LT is a solution to a part of the design problem. That is, to extend LF range downward by introducing a shelf filter. But it introduces a new problem: possible LF overload. A complete solution would include a high-pass filter to limit LF energy into the woofer. However, it does not need 2 sections (i.e., LT + HPF): a single peaking HPF can achieve both.
LT is a solution to a part of the design problem. That is, to extend LF range downward by introducing a shelf filter. But it introduces a new problem: possible LF overload. A complete solution would include a high-pass filter to limit LF energy into the woofer. However, it does not need 2 sections (i.e., LT + HPF): a single peaking HPF can achieve both.
How do I get a wattage figure from this? Calculators want me to add power factor into the equation to derive Watts.
look at the graph on post 1.
green is the resultant curve.
to achieve this curve, the red eq is needed
the red eq is not a hpf.
shelf filter is a shelf filter.
just turn up the bass knob.
and basically yes adding a second woofer
will flatten the response as is.
So less boost is needed.
Since a basic .5 crossover would be done to boost
below baffle step losses and flatten the response.
Plain English it already has more bass with second
woofer. But yes if you do boost bass.
You have a second woofer and the extra linear travel ( Xmax)
to feasible get more SPL.
In real life same listening levels, just less fart out with big bass dynamics.
Dont need spend much time calculating power stuffs.
It is what it is.
Doubling woofers will improve the capability to not reach distortion
quicker. And you get what yah get with chosen woofers.
225 pretty good woofer as is.
Fs is 28 Hz so low tuning is easy.
So when you goose the EQ the port doesnt
bloom. Like annoying high tuned systems
tuned high 45 , 55, 65 Hz etc etc.
Most " bass" detail what people think is " Sub"
is not 20 Hz. The nice transients are 30 to 60 Hz
so as long as the port is NOT there.
You get nice accurate bass.
Dual woofers even better
just turn up the bass knob.
and basically yes adding a second woofer
will flatten the response as is.
So less boost is needed.
Since a basic .5 crossover would be done to boost
below baffle step losses and flatten the response.
Plain English it already has more bass with second
woofer. But yes if you do boost bass.
You have a second woofer and the extra linear travel ( Xmax)
to feasible get more SPL.
In real life same listening levels, just less fart out with big bass dynamics.
Dont need spend much time calculating power stuffs.
It is what it is.
Doubling woofers will improve the capability to not reach distortion
quicker. And you get what yah get with chosen woofers.
225 pretty good woofer as is.
Fs is 28 Hz so low tuning is easy.
So when you goose the EQ the port doesnt
bloom. Like annoying high tuned systems
tuned high 45 , 55, 65 Hz etc etc.
Most " bass" detail what people think is " Sub"
is not 20 Hz. The nice transients are 30 to 60 Hz
so as long as the port is NOT there.
You get nice accurate bass.
Dual woofers even better