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How Cheap is Your Sub?

watchnerd

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Sorry, but I can't help but think this topic should have a soundtrack that matches the title:


But seriously, I've read about two radically different schools of thought when it comes to subs:

1. If you have high SPL, low distortion mains, you need a 1-2 very expensive subs if you hope to hit >100 dB with distortion low enough to match the mains.

or

2. Our ears aren't very sensitive to bass distortion, but they are sensitive to room nodes. More, but cheaper, subs (2-4) fixes the real problem, which is the room.

Where do you weigh in and how cheap are your subs?
 

DonH56

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I have four subs that ran about $1k each. My original auditions showed them to be comparable to subs in the $3k+ range but it was sighted and independent so who knows. At least they measure well. My room has poor dimensions so multiple subs properly placed provide much more even frequency response and SPL is not a problem. They play much more loudly than I can stand (even when I only had a pair) and distortion is low (servo designs). Because of SBIR and room modes I would always choose multiple smaller subs over one big one, though with two you have a shot at evening the FR if you can place them optimally.
 

RayDunzl

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I have 4 that were $180 each delivered (new).
 
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watchnerd

watchnerd

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Subs need to be powerful enough to not bottom out at the SPL you need. Once there, multiple subs is the way to go.

There's a pretty big delta between high distortion (without bottoming out) and bottoming out. Are you saying that distortion basically doesn't matter?
 

Blumlein 88

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I have a friend with some very expensive and very, very good Rythmik servo subs. I helped him match them to Soundlabs successfully.

I, being sneaky, also convinced him to try some Dayton Audio subs in his video set up from Parts Express. Was considering them myself, so why not get a friend to try them out? So they are each about 10% the cost of his Rythmiks. My feeling being we really are talking something that needs to be built good enough to cover 2 octaves. If the box is right sized, the drivers and box aren't junk how tough can it be? For their size they have less power and lower loudness capability, but you can afford to get two or three or four and spread them around the room. Directionality isn't an issue at those frequencies. Room position is.

Well it works out very nicely. If you could only do one, the Rythmic is a better sub. If you aren't space constrained 4 Dayton subs have some advantages in distributing nodes and might be roughly on par for less overall money. Would 4 Rythmiks be even better. Yeah, but not by so much. The Daytons do what their specs claim, and having multiple positions is very helpful. I was encouraged by Ray's measurements of them. I also have seen measurements over on the AV forums showing they weren't junk. Now I have measured them too.

So Dayton's are well down the cost scale and do work. The more cheaper subs is definitely easier to get working pretty well. I have considered how well they might work if I just lined about 6 up each side wall of my listening room. Or maybe stacked 4 in each front corner.
 

NorthSky

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RayDunzl

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My reasoning/rationale for cheap sub:

https://www.parts-express.com/dayton-audio-sub-1500-15-150-watt-powered-subwoofer--300-634

  • Mains alone making 100dB bass peaks - using Audacity risset drum (50Hz) slowed down to get lower (25Hz center frequency) was essentially "enough".
  • 88dB sensitivity (or so) at 1W (2.83v) means 100dB is maybe about 15W (or 2W and 30W if 4Ohm)
  • I'm not a nutty bass headbanger, so, figured the cheap sub plate amp (150W) headroom would be sufficient given the above.
  • Spreading the load among additional acoustic sources on each side - 1 12" woofer + 2 15" CheezeWoofers means even less power needed for each driver.
upload_2017-10-3_6-59-27.png

  • That calculation says I only "need" the subs to run barely off idle.
  • Lower output level = lower distortion products
  • Didn't need fancy controls, I would apply that elsewhere (DSP).
  • Not into shiny stuff that much, so vinyl applique finish (black) good enough.
  • WAF not a consideration using my definition of WAF.
My audio buddy has a pair of 12" paper cone Rythmiks. I lusted a little (that's what prompted me) but figured I'd experiment a bit first, especially since you just gotta spread the drivers around the room (I haven't, yet). They only have 300W if I remember correctly.

Example Measurement - Left and Right - Subs alone (red) and with Mains (black) with miniDSP modifying the signal. Sub output overlaps mains (full range), no separate crossover.

upload_2017-10-3_7-14-8.png


Adding a crossover (more DSP) is under consideration, I want to try additional phase control around 47Hz).

When left and right sing together there's a measurably severe but seemingly inaudible dip caused by room induced phase anomaly:

upload_2017-10-3_7-33-43.png
 
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watchnerd

watchnerd

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I have a friend with some very expensive and very, very good Rythmik servo subs. I helped him match them to Soundlabs successfully.

I, being sneaky, also convinced him to try some Dayton Audio subs in his video set up from Parts Express. Was considering them myself, so why not get a friend to try them out? So they are each about 10% the cost of his Rythmiks. My feeling being we really are talking something that needs to be built good enough to cover 2 octaves. If the box is right sized, the drivers and box aren't junk how tough can it be? For their size they have less power and lower loudness capability, but you can afford to get two or three or four and spread them around the room. Directionality isn't an issue at those frequencies. Room position is.

Well it works out very nicely. If you could only do one, the Rythmic is a better sub. If you aren't space constrained 4 Dayton subs have some advantages in distributing nodes and might be roughly on par for less overall money. Would 4 Rythmiks be even better. Yeah, but not by so much. The Daytons do what their specs claim, and having multiple positions is very helpful. I was encouraged by Ray's measurements of them. I also have seen measurements over on the AV forums showing they weren't junk. Now I have measured them too.

So Dayton's are well down the cost scale and do work. The more cheaper subs is definitely easier to get working pretty well. I have considered how well they might work if I just lined about 6 up each side wall of my listening room. Or maybe stacked 4 in each front corner.

I see several on this page. Which did you get?

http://www.daytonaudio.com/index.php/home-audio-video/finished-speakers/subwoofer-systems.html

(I guess it applies to @RayDunzl if his cheap subs are Dayton's, too)
 

RayDunzl

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DonH56

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Mine are Rythmik F12's, sealed, 370 W amp, Al cone. Since theoretically each sub can add 6 dB SPL (driver + amp) then four subs could add 18 dB over a single sub. That's a lot of extra power and means the individual subs need not run nearly as loud. The curves compress in the LF region so, unlike midrange where 10 dB sounds roughly twice as loud, for subs doubling in perceived volume may only require 5~6 dB. So if you add another sub you can really downsize and keep the same SPL, IF (a big if!) you actually attain that SPL increase. In practice it will vary a bit with frequency and such, but also remember a properly placed additional sub that counters a null can have a much larger effective gain, like 20 ~ 40 dB in-room.

Any driver typically exhibits higher distortion well before bottoming out, but it depends upon the driver (and amplifier) parameters. There are many parameters and trades so I'll defer to speaker designers. One thing to bear in mind is that distortion in a sub often makes them sound louder and "fuller, richer" to listeners because, esp. for very LF signals, it is much easier to hear the distortion than the fundamental.

About all I know on the subject, carry on.
 

Sal1950

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But seriously, I've read about two radically different schools of thought when it comes to subs:

1. If you have high SPL, low distortion mains, you need a 1-2 very expensive subs if you hope to hit >100 dB with distortion low enough to match the mains.
Not only distortion but speed, that dynamic factor is an issue when attempting to mate a sub to an existing system that will sound relatively seamless..
Back in around 1990 I was looking to add some deep bass to my Klispch La Scala's. At that time the only thing I could find in my $ wheelhouse were the then new HSU HRSW12's build in 7' tall sonotubes, 12" driver facing up and ported out the bottom. Don't remember the numbers any more but they were fairlhy efficient and measured like 3db down at 16HZ IIRC. Crossing over around 60hz and driving a stereo pair with pair of 600 w monoblocks they did a reasonable job of hanging with the big K-Horns when the going got ruff at Sal's, which happened quite often back in the day. :)
attachment.php
 

Sal1950

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I have this one (four):
Those should more a lot of air without strain, with 4 sharing the load distortion should remain minimal.
So long as you have the room they look like excellent choices.
You could do better but at a significantly higher cost.
The Audio Cheapskate gives you 4+ stars.
 

Jinjuku

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I have two DIY Infinity Kappa 12.1w in a dual opposed with a Behringer iNuke 3000DSP placed in room to deal with room modes. About $1400 all in. Dialed it out with a Dayton Omni-mic and it's superb. Rest of the family hates it.
 

RayDunzl

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Sal1950

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Describe "speed".
That kind of stuff is your job Scrutinizer. You the super duper speaker measurement guy. Impulse response? Ability of the cone to accelerate?
 

DonH56

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Speed is a misnomer as applied to subs IME/IMO. How much "speed" is there when the signal is rolled off over 80 Hz or whatever? I have found it tends to fall into just a couple of issues, integration with the mains and underdamped/ringing subs. Integration problems tend to revolve around getting the mains and sub(s) in phase at the crossover point so they all move together. Subs that have high distortion and poor time response tend to add harmonics and "fill in" the space between percussive attacks but the latter is much more subtle and has little to do with "speed" in a conventional sense.

All IMO - Don
 
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