Good dual 8 ohm subwoofer?

The only speaker vendor I have experience with is Parts Express. It's slim pickings and the only one I see that's close is this. Dayton Audio SD315A-88 12" DVC Subwoofer Close but no cigar. It's nice, especially considering the price, but I think I'll need more output.

I hope to keep enclosure volume below 2.5 cubic feet, subwoofer ideally under $300. I want dual 8 ohm voicecoil so I can drive it with an amplifier I already have set up, or else drive it with a mono amplifier and voice coils paralleled.

I mostly listen to jazz, blues, and classic rock (pretty much in that order) but sometimes I listen to more modern music. My present system (8" 2-way) is perfect for jazz and blues (and classical sounds great) and handles classic rock at loud volumes pretty well too. But some music I come across has a whole lot of high spl, lower octave content. The speakers can't handle it at a reasonably loud volume. Since I like to listen to hip-hop sometimes, and demanding music like Perfect Circle (drives my woofers nuts) sometimes, and since thanks to the bluetooth a lot of people listen to it, I would like to add that last octave to my system.

This is for music, not boom boom. Sealed enclosure preferred but not required. I'm hoping someone an idea for an appropriate driver. Thanks.
 

snappyturtle

Member
2014-01-25 12:55 pm
8ohm subs haven't been popular in the modern era. Once class d architecture became a thing and amplifier power became cheap, low impedance drivers led the way.
Expanding your search to 4ohm drivers will net better results. Dual 2 ohm coils can be wired in series etc.

If you think perfect circle is bad, try tool.
 
I know there's way more 4 ohm subwoofers. I don't have class D anything. The amplifier I'm going to use (repurposed brain dead AV receiver gutted and rebuilt as 4 channel amplifier with adjustable active crossover) drives 4 ohm loads but the power supply sags a lot. It was originally rated the same power into 4 or 8 ohm loads (125 watts RMS x 5), which tells you that it's really intended for 8 ohm loads. It's a monstrous behemoth that doubles as a space heater so I don't want to push it.
 
I know there's way more 4 ohm subwoofers. I don't have class D anything. The amplifier I'm going to use (repurposed brain dead AV receiver gutted and rebuilt as 4 channel amplifier with adjustable active crossover) drives 4 ohm loads but the power supply sags a lot.

I use one of those 4-channel AV amps in a secondary system. Just fine.

Don't forget, if your power rails sag in getting over 25 volts, that goes twice as much power into a 4 Ohm driver. You might get lots of loudness.

Depending on the crossover freq, you might give some thought to mixed bass.

B.
 
Sounds like you have an old Technics receiver there... :)

JVC. It's a modular design with about ten different boards in there; some obviously not built in house. Every power amp is on a separate board. It's perfect for gutting and rebuilding with a different configuration!

The power amp boards are basically the Pass "blameless" topology. It didn't take long for me to realize they're very similar to the amplifier boards I built a few years ago and that I'm using right now. And they use good old Sanken output transistors. You can build a more complex amplifier, but you'd be well past the point of diminishing returns.

I think it's going to kick my system up a notch once I get it all set up.

I have a stack of brain dead AV multichannel receivers in storage. Denon, Onkyo, JVC, Sony. Some of these have what's practically a mini laptop inside of them. Does anyone actually repair these? They all do the same thing; the computer goes nuts and then nothing works. I plan to start gutting them for parts.
 
I use one of those 4-channel AV amps in a secondary system. Just fine.

Nice to know.

Don't forget, if your power rails sag in getting over 25 volts, that goes twice as much power into a 4 Ohm driver. You might get lots of loudness.

I think they design them like this. I'm still inclined to avoid 4 ohm subwoofers.

When I build an amplifier, I put extra beef in the power supply to avoid sag. They deliver the goods right up to clipping. I realize this means more heat etc but it always delivers the last decibel, instead of falling apart like commercial amplifiers. And I've reverse engineered enough units to know that engineers intentionally put wimpy power supplies in consumer products, which allows for a cheaper and more reliable build overall - it's cheap SOA protection and allows cheaper transistors and smaller heat sinks to be used.

Depending on the crossover freq, you might give some thought to mixed bass.

I'm not sure what you mean by "mixed bass."
 
I'm not sure what you mean by "mixed bass."

Those amps can work great for bi-amp systems, just set to DVD-4 channel. As far as sound quality, better than today's best speakers. So a good match.

Big debate about bothering to have separate L and R for recordings below point where directionality is possible. I've mixed L and R on most of my systems below 130 Hz since 1968. You can have as many subs as you want (not less than one, of course*) and put them where you want and have a choice in how to amplify.

B.
* I don't like to be vague in my arithmetic specification
 
Those amps can work great for bi-amp systems, just set to DVD-4 channel. As far as sound quality, better than today's best speakers. So a good match.

Big debate about bothering to have separate L and R for recordings below point where directionality is possible. I've mixed L and R on most of my systems below 130 Hz since 1968. You can have as many subs as you want (not less than one, of course*) and put them where you want and have a choice in how to amplify.

B.
* I don't like to be vague in my arithmetic specification

All the controls have been gutted. I'm fitting an active crossover and subsonoic filter. There will be a couple of switches; one to choose between four channel and bi-amp operation, and one to select the crossover frequency. That's it.

And placing subwoofers "anywhere" can cause interference between subwoofer and sattelites ( and subsequent nodes) at the crossover. Rule of thumb is to place subwoofers no farther than a quarter wave apart at the crossover frequency. So two subwoofers really are better than one.

At midrange frequencies we can control this interference with waveguides and even a strip of felt on the baffle. But it's pretty hard to control the dispersion at low frequencies.

It's not about directionality, because low bass frequencies are not really directional.
 
...And placing subwoofers "anywhere" can cause interference between subwoofer and sattelites ( and subsequent nodes) at the crossover. Rule of thumb is to place subwoofers no farther than a quarter wave apart at the crossover frequency. So two subwoofers really are better than one.

At midrange frequencies we can control this interference with waveguides and even a strip of felt on the baffle. But it's pretty hard to control the dispersion at low frequencies.
You might wish to "catch up" on recent thinking on multiple sub installation. Biggest debate on this forum, excepting how to sim 9th order cabs.

B.
 
You might wish to "catch up" on recent thinking on multiple sub installation. Biggest debate on this forum, excepting how to sim 9th order cabs.

B.

I haven't been following subwoofers here. I'm just employing the same concepts you'd use to smooth out the crossover region for a midrange or tweeter crossover. We know that if you place the tweeter too far from the midrange (or woofer in a two-way) that you'll create an interference pattern that will be quite audible and unpleasant, unless you control the dispersion of the tweeter.

Can you give me the cliff notes? I do understand interference and diffraction. Thanks.
 
Talking about phase when playing an overproduced recording in a room is just applying 7th grade Euclidean geometry to winning beach volleyball: some relationship but not much.

Here's a thread with 360,000 hits.

Multiple Small Subs - Geddes Approach

B.

I'm sticking with a single sub. This will require me to stick to established principles that I know work.

I've heard multiple (BIG, not small) subs in a club before. Sounded great, but the whole room was set up for sound and each subwoofer is as big as my bathroom. No thanks.

I hear you about overproduced recordings. I'm already way past the point where the production of the music is often the limiting factor for quality sound reproduction. I cuss music producers almost every time I listen.
 

freddi

Member
Paid Member
2005-08-16 4:21 pm
here's the MCM used by the late Marshall Leach - meets specs - Re in parallel 3.3 ohms

https://www.newark.com/mcm-audio-select/55-1465/woofer-12-dual-voice-coil/dp/34C6021


Kq2w1ja.gif
 
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here's the MCM used by the late Marshall Leach - meets specs - Re in parallel 3.3 ohms

https://www.newark.com/mcm-audio-select/55-1465/woofer-12-dual-voice-coil/dp/34C6021


Kq2w1ja.gif

Thanks. Link goes to Newark homepage on my browser.

Now I realize that this unit is supposedly designed to drive 4 ohm main speakers. It even has provisions to connect 2 pairs of speakers to the front output. The front and rear amplifier boards are very similar, but a little different. Front is rated 125 watts/channel into 8 or 4 ohm. Rear is rated 100 watts/channel into 8 ohm. It was a 5 channel amplifier. Now it's a four channel amplifier. The center channel amplifier board has been removed.

You see where this is going. I can probably get away with a 4 ohm dual voice coil subwoofer. :) I'm going to take a look. It makes it a lot easier and will hopefully yield better results.