For few years I have Alpine SWR-1542D. On paper it looks nice but so far I am not impressed.
I have it in my car and have it paired with Hertz ML Power 1 amp. 1542D has RMS 750W and I was pushing 1000W with the amp, no problems.
As it's a 15" sub, it's a bit on the bigger side but I wanted a sealed enclosure anyway as it's simple to make and I wanted to focus more on SQ. I made a sealed enclosure recommended by the Alpines manual. Which was ~46L net volume. Big mistake as it is underwhelming.
This is what I built:
Odd shape shouldn't be a problem?
Anyway with Qtc at 0.806 it should have fsc at 43 Hz. And this is what the transfer function magnitude looks like with 18 Hz 24 dB/Oct highpass filter and 120hz 24 dB/Oct lowpass:
Blue is Alpine recommended 46L sealed enclosure and red is WinISD recommended enclosure around 73L, fsc 37 Hz, Qtc 0.707. F3 at 40 Hz.
If highpass and lowpass filters are working as they should then this should give pretty good idea how it's going to perform?
Now I want to make a bigger enclosure and I feel like I want to try 6th order bandpass enclosure with a "neat" trick of making front and back chambers separateble so I can remove front chamber by unbolting it and using back chamber as smaller vented enclosure if needed. Might be dumb idea?
I am also wondering if perhaps my amp is limiting performance of my sub with the highpass filter always on? Especially for the sealed enclosure? With it on, according to WinISD my cone excursion can barely do over half, around 12-14mm of its Xmax which is 20.5mm.
Whether going with vented enclosure or 6th order bandpass, I have roughly available gross volume 208 - 228L, around half of my trunk space. Should be big enough.
I have calculated using WinISD that 108L vented box tuned to 28Hz would give me transfer function magnitude ( Green ):
This is probably too peaky. Should I try to flatten it out?
108L tuned to 24Hz ( Orange ):
Here are my SWR-1542D T/S parameters:
I need to fiddle around more in WinISD and see if I can set up 6th order bandpass so it gives a decent flat response with good enough low end. But that's for another day. Meanwhile I don't mind to get some tips and tricks to help me figure out a suitable setup.
Regards,
Karl
I have it in my car and have it paired with Hertz ML Power 1 amp. 1542D has RMS 750W and I was pushing 1000W with the amp, no problems.
As it's a 15" sub, it's a bit on the bigger side but I wanted a sealed enclosure anyway as it's simple to make and I wanted to focus more on SQ. I made a sealed enclosure recommended by the Alpines manual. Which was ~46L net volume. Big mistake as it is underwhelming.
This is what I built:
Odd shape shouldn't be a problem?
Anyway with Qtc at 0.806 it should have fsc at 43 Hz. And this is what the transfer function magnitude looks like with 18 Hz 24 dB/Oct highpass filter and 120hz 24 dB/Oct lowpass:
Blue is Alpine recommended 46L sealed enclosure and red is WinISD recommended enclosure around 73L, fsc 37 Hz, Qtc 0.707. F3 at 40 Hz.
If highpass and lowpass filters are working as they should then this should give pretty good idea how it's going to perform?
Now I want to make a bigger enclosure and I feel like I want to try 6th order bandpass enclosure with a "neat" trick of making front and back chambers separateble so I can remove front chamber by unbolting it and using back chamber as smaller vented enclosure if needed. Might be dumb idea?
I am also wondering if perhaps my amp is limiting performance of my sub with the highpass filter always on? Especially for the sealed enclosure? With it on, according to WinISD my cone excursion can barely do over half, around 12-14mm of its Xmax which is 20.5mm.
Whether going with vented enclosure or 6th order bandpass, I have roughly available gross volume 208 - 228L, around half of my trunk space. Should be big enough.
I have calculated using WinISD that 108L vented box tuned to 28Hz would give me transfer function magnitude ( Green ):
This is probably too peaky. Should I try to flatten it out?
108L tuned to 24Hz ( Orange ):
Here are my SWR-1542D T/S parameters:
I need to fiddle around more in WinISD and see if I can set up 6th order bandpass so it gives a decent flat response with good enough low end. But that's for another day. Meanwhile I don't mind to get some tips and tricks to help me figure out a suitable setup.
Regards,
Karl
Shape is not a problem
They won't give you any idea of what the response in the car will be.
The HP filter shouldn't limit excursion at frequencies above it's set point, at which point it could be -3dB or -6dB depending on the filter type. -6dB cuts excursion in half.
A +3dB peak is not much compared to the typical transfer function of a vehicle, which may be +6 to 12dB or more.
If you have not measured the vehicle's transfer function, you are shooting in the dark with cabinet design for it.
https://www.diyaudio.com/community/threads/transfer-function-measurement-and-use.350963/
Makes sense. I need to add cars transfer function on top of the enclosures transfer function and only then I can use HP/LP filters in order to understand how these filter affect the output. So if I just used HP filter at 18hz 24dB/Oct on a enclosures transfer function in WinISD and it shows that excursion lets say is going to max out at 12mm but once I have everything in the car then with cars own transfer function on top of everything I may end up with much higher excursion at like 24mm? Which means I may need to increas HP to 20hz or more to bring down excursion? This means I may not be limiting the low frequency performance of my subwoofer with a HP that goes down only to 18hz.
Ok I'll do my best to measure transfer function of my car. I luckily have sealed enclosure. And I have pretty good microphone, but not prefered for this sort of application.A +3dB peak is not much compared to the typical transfer function of a vehicle, which may be +6 to 12dB or more.
If you have not measured the vehicle's transfer function, you are shooting in the dark with cabinet design for it.
https://www.diyaudio.com/community/threads/transfer-function-measurement-and-use.350963/
I am also slowly adding some sound deadening to my car. Starting from the trunk and later when upgrading door speakers I am going to be installing some in the doors and rest of the cabin. Which is all going to affect cars transfer function... I should add sound deadening before I even build my new sub enclosure.
I don't need my sub to be super loud, I don't think I am even going to go over 100dB unless I want to fool around. I just need it to be louder than my current sealed enclsosure which sadly sucks. I am aiming more towards sound quality rather than SPL.
No, excursion does not change, output SPL vs excursion in the car changes according to the car's transfer function. The car's transfer function may add +6 to 12dB of low frequency, or may suck out certain frequencies depending on the sub woofer placement.
You simply need to equalize your enclosure to the response you desire, instead of one that "sucks".
I agree. There is lots of road noise, so a flat response after factoring the cabin gain might not be ideal. My subwoofer is tuned to be flat without cabin gain.
As you do not require crazy SPL, I would suggest to buy a DSP and use that to extend the low frequencies. That is assuming that you care about trunk space. If not, a big enclosure might be cheaper and has the capability to play louder.
As you do not require crazy SPL, I would suggest to buy a DSP and use that to extend the low frequencies. That is assuming that you care about trunk space. If not, a big enclosure might be cheaper and has the capability to play louder.
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Ok I got confused because what I did was trying to approximate cabin gain ( cabin gain is same as cars transfers function, right? ) using linkwitz transform filter in WinISD and then looked at the cone excursion which went way up.
I want to get DSP but I'll be doing that once I am upgrading door speakers.
I am still planning to fill half of the trunk with a subwoofer. My current preliminary design is around 125L ( ~4.4 ft3 ) in net volume.