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Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: Dennis S
Date: February 25, 2018 04:58PM
When listening to music, I'd like my bass to be strong and accurate, but not necessarily ultra-low. Maybe down to 35-40hz. To keep from buying new amps, can I make two cabinets with woofers or subs that go down in the 30's and hook them up in stereo to an old Sony, Pioneer, etc. receiver? I would put low-pass filters at the appropriate level and bi-amp with my regular stereo receiver. Without getting into the weeds since I don't have measuring equipment and don't know much about this except having a good ear, will this work?



Edited 1 time(s). Last edit at 02/25/2018 05:16PM by Dennis S.
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and a high pass filter?
Posted by: zachdog
Date: February 25, 2018 05:13PM
Yes, it would work fine. I have a system like this that uses a 1980s Pioneer receiver and a custom-made active crossover along with a homemade cabinet and a dual-voice coil woofer. It was a fun project!



Edited 1 time(s). Last edit at 02/25/2018 05:13PM by zachdog.
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: Frank
Date: February 25, 2018 06:36PM
Matching the cabinet design with the speaker is critical for good low end response. I'm sure you can find all the parameters on-line. Might be cheaper to find some ready made old loudspeakers or even a used sub but be sure the surrounds are still good. Good luck!
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: Filliam H. Muffman
Date: February 25, 2018 07:45PM
How big a cabinet will your wife allow?


This link can take a long time to load. audiojudgement.com/folded-horn-speaker-design/



In tha 360. MRF User Map



Edited 1 time(s). Last edit at 02/25/2018 07:51PM by Filliam H. Muffman.
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: Buzz
Date: February 25, 2018 07:55PM
No weeds, in theory, yes. I've done it a couple of times, albeit last century, but I know "some people" that know their stuff, and they spec'ed it out for me both times. One came out fabulous, and the other was totally awesome. While I probably have the capacity to learn what to do, I don't think I would attempt such a project by ear alone. I think you can probably come pretty close just looking up some standard configs online, but a real audiotechnofile would be a good friend to have for this. For these types of projects, I hate leaving any goodness unfulfilled, knowing that with a nudge or two in the right places, it could've been better/perfect. If you're not that OCD, go ahead and wing it.
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: mikebw
Date: February 26, 2018 08:36AM
Probably will be good enough.

Without knowing the T/S parameters of the drivers, or the volume of the cabinets it will be difficult to build a good crossover, but again if you're not too demanding it should be OK. How powerful are your old amplifiers? To get the lows as loud as the highs you'll need proportionally more power.

One of the more fun projects I ever did was to retrofit an old 10" subwoofer in a big cabinet (6.2 cu. ft.), with a new 15" woofer and 240w plate amplifier. Sure I've mentioned that before, but it's been a while. It's been rockin' for over 10 years now, and well worth every dollar spent.
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: pdq
Date: February 26, 2018 09:08AM
I would recommend diyaudio.com.

When we decided to add some cabinets to our 10 ft tall family room, I realized that the way the main one that holds the TV cuts the corner it would leave a sizable triangular-shaped dead space behind. Rather than just leave that space empty, I designed and built a triangular-cross-section exponential bass horn subwoofer out of mdf board. The wife let me do this because it’s entirely hidden by the now-built-in cabinets.

The idea was that the first segment of the horn (about seven feet) was the vertical part behind the cabinet, and then it takes a 90degree turn into the room where that last part of the horn is actually formed by the ceiling, corner walls, and top of the cabinet, resulting in a ~8 foot wide rectangular “mouth”. (To be effective, bass horns have to be really big).

In practice, the 90 degree bend, I think, (and perhaps the triangular cross section of the first part) causes some irregularities in the frequency response, but it can do a sine wave down to 30 hz. And horn-loading a subwoofer increases the efficiency by 10x to 100x, so that single 12” woofer can shake the room in your typical action movie soundtrack. And it was a fun project for an old-ish audio-head.

Anyway, to get back to your point, repurposing the old receiver should be fine. (My setup uses a little 20 watt amp to power the sub- like I said, it’s very efficient). I’m not sure if you even need to do any crossover if you’re using a separate amp- you could just turn down the treble on the old receiver if you wanted.
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Re: Can you make a pseudo subwoofer with some good woofers, an old receiver, and low-pass filters?
Posted by: mikebw
Date: February 26, 2018 09:16AM
Quote
pdq
Anyway, to get back to your point, repurposing the old receiver should be fine. (My setup uses a little 20 watt amp to power the sub- like I said, it’s very efficient). I’m not sure if you even need to do any crossover if you’re using a separate amp- you could just turn down the treble on the old receiver if you wanted.

Excellent points. I agree one could use the EQ on the old receiver, and that would save come cost since big audio grade inductors can be expensive. Horn loading is great if you have the space.
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