Active or servo control subwoofer

[John6289]

Is self powered active sub woofer generally viewed as higher grade than non powered unit?

Is it just a simple act of relocating the amplifier from receiver into the speaker box?

Does it work better due to shortening the length and resistance of wiring between amp and speaker coil?

Is "active subwoofer" just use normal amplifier or use servo controlled amplifier, as those in early leader Velodyne?

Is Onkyo SKW-591 servo contolled?

 

[John6289]

SKW-591 is kit sub woofer for HTiB HT-S7800 set

 

[lovinthehd]

The sub needs power from an amp. Whether the sub has an on-board amp or an external amp is mostly about amp longevity IMO; plate amps tend to fail sooner. Receiver amps usually do not power subwoofers except with HTIB sets. HTIB subs tend not to be very good. Servo is a type of amp/sub driver interface...a few companies use that technology (like Rythmik).

 

[AcuDefTechGuy]

I've used externally-powered subs (AKA passive subs or non-powered subs) for over 25 years now.

My subs are powered by ATI and RBH external amps.

I don't think the little plate amps that fit into the subs are considered "higher grade".

 

[Leemix]

Is self powered active sub woofer generally viewed as higher grade than non powered unit?

Is it just a simple act of relocating the amplifier from receiver into the speaker box?

Does it work better due to shortening the length and resistance of wiring between amp and speaker coil?

Is "active subwoofer" just use normal amplifier or use servo controlled amplifier, as those in early leader Velodyne?

Is Onkyo SKW-591 servo contolled?

1: almost all subs used in a home environment are active powered. Some impressive systems use passive ones with external amplification, active crossovers and room correction but its complicated and expensive.

2: not in most of them/the decent ones. Some even have advanced room correction in them.

3:whats the most beneficial i dont know but you will still have to have a signal cable all the way to the sub. I think practicality is the key here not any tiny benefit or opposite.

4: both types would be active subwoofers.

5: dont know and at that level of sub i doubt it matters at all, servo or not isnt really a great concern in general.


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[BMXTRIX]

The goal of a servo controlled subwoofer is to more accurately control the speaker itself for more accurate bass reproduction. In theory, this could use an internal (active) or external (passive) setup, but I believe the amplifier needs to be built around the concept of the speaker being servo-controlled and handle it correctly.

http://www.rythmikaudio.com/DirectServo.html

Active subwoofer: Has the amplifier built in.
Passive subwoofer: Requires an external amplifier.

Good servo subs sound phenomenal, and often have a matching price. ($$$$$)
But, most subwoofers are active. They have an amp built into them. This is 'traditional' subwoofer design and makes sense as the amplifier can be matched to the speaker that is inside of it exactly. Most A/V receivers do not have amplification built in for a woofer, and so in almost all cases you MUST use some sort of external amplifier to power the speaker. That amp can be built into the subwoofer box, or not. Since it's easiest to build it in and sell it that way, that's most common. That way, the wiring is also consistent to a subwoofer. Just a coaxial cable to carry the signal from an A/V receiver to the subwoofer.

Some VERY entry level home theater in a box kits use non-standard setups. They have a powered subwoofer output that runs directly to a non-powered woofer box. This is convenient for them, but it may make a subwoofer upgrade problematic.

If you are looking for a good subwoofer, come up with a budget and ask specifically about the best sounding subs at or near that price point. Be aware that subwoofers generally sound better and hit harder with greater accuracy with the more money that is spent. I swear by sealed subwoofer enclosures with pretty significant price tags. Every time I listen to a cheaper model I often find them boomy. There's a reason the reputable brands have $1,500+ subwoofers out there. Highly respected value brands still end up with those pricey models for a reason.

 

[lovinthehd]

OTOH servo subs haven't proved to be particularly effective either.

 

[mtrycrafts]

1: almost all subs used in a home environment are active powered. Some impressive systems use passive ones with external amplification, active crossovers and room correction but its complicated and expensive.

...

My passive subs are not expensive, wasn't, and works just fine from the LFE out on the receiver. I do use an outboard Behringer EQ before the amp though. Even active subs need EQ unless it is onboard the plate amp.

 

[John6289]

Is Velodyne considered as top or near-top in active servo sub?

 

[BMXTRIX]

Is Velodyne considered as top or near-top in active servo sub?

Velodyne makes all types of subwoofers. Only a few of their top end models are servo controlled, the rest are standard active subwoofers, or passive subwoofer/amplifer kits.

They are typically well regarded, but also considered pricey many times. It all depends on your budget and what you are looking for specifically in terms of bass. This will depend in some part on your room size, but also your budget. You should really just state the size of your room and the budget for your subwoofer then ask for recommendations. I'm not the best to give recommendations as I haven't done any subwoofer shopping recently and I tend to look towards more expensive models. Check your local Craigslist as well because there are people that upgrade and offer great deals on their old units they are no longer using.

For Velodyne, their cheapest servo model is about $3,000.
http://velodyneacoustics.com/subwoofers.html

If that's your budget, you may be better served with a couple of SVS Subwoofers.
There are those who would argue that servo controlled models may also add little to no value to the final product. I'm not going to disagree. At the end of the day a good subwoofer is a good subwoofer, and I wouldn't get hung up on whether it is servo controlled or just a standard subwoofer.

I prefer sealed enclosures, but have no demand for servo controls. I would likely look at something like this:
https://www.svsound.com/pages/16-ultra-series
Or look for a used JL Audio model.

So, not exactly on the lower price end for me.

 

[snakeeyes]

So far my living room HSU subs are performing similiar to my theater room Rythmik servo sub. HSU VTF2 vs Rythmik LVX12. Yes the finish is nicer on the Rythmik subs in black oak visually. Not sure servo is a game changer as far as sound. These are both great companies. (I understand SVS is as well). Yes these are only ported 12s and maybe it matters more with 15 inch. I also have a sealed Rythmik L12 sub as well in my bedroom setup which is also servo.

 

[mtrycrafts]

Don't forget that distortion at the sub band is much harder to detect than in the mid bands, as best I know. Nousaine used a 10% benchmark to measure subs.

 

[shadyJ]

Don't forget that distortion at the sub band is much harder to detect than in the mid bands, as best I know. Nousaine used a 10% benchmark to measure subs.

10% THD is a pretty arbitrary number for distortion detection thresholds in bass frequencies. The physics of bass and also the sensitivity of our ears changes so much in deep frequencies that THD quantities don't mean much unless they are extremely low or extremely high.

 

[mtrycrafts]

10% THD is a pretty arbitrary number for distortion detection thresholds in bass frequencies. The physics of bass and also the sensitivity of our ears changes so much in deep frequencies that THD quantities don't mean much unless they are extremely low or extremely high.

Knowing Nousaine he had a reason for picking 10%. If I remember as it wasn't yesterday, he tested subjects. Some couldn't hear 100% someplace in the low band, perhaps closer to 30Hz? But, it is now too late to ask him.

Addendum:
https://www.axiomaudio.com/blog/distortion#

 

[shadyJ]

Knowing Nousaine he had a reason for picking 10%. If I remember as it wasn't yesterday, he tested subjects. Some couldn't hear 100% someplace in the low band, perhaps closer to 30Hz? But, it is now too late to ask him.

Addendum:
https://www.axiomaudio.com/blog/distortion#

That article isn't very detailed or scientifically rigorous. I wouldn't put too much stock in the conclusions there, although generally they are correct that distortion is much more difficult to detect in low frequencies than high frequencies. A much more detailed- and also peer-reviewed- study was done by Louis Fielder and Eric Benjamin (Fielder, Louis D., and Eric M. Benjamin. "Subwoofer performance for accurate reproduction of music." Journal of the Audio Engineering Society 36.6 (1988): 443-456.), which was conducted in true laboratory settings, and this is a much more precise examination of the subject. I describe their findings on page 3 of this article. If you really want to know how audible harmonic distortion is in bass frequencies, look at table 2 in that article.

 

[mtrycrafts]

That article isn't very detailed or scientifically rigorous. I wouldn't put too much stock in the conclusions there, although generally they are correct that distortion is much more difficult to detect in low frequencies than high frequencies. A much more detailed- and also peer-reviewed- study was done by Louis Fielder and Eric Benjamin (Fielder, Louis D., and Eric M. Benjamin. "Subwoofer performance for accurate reproduction of music." Journal of the Audio Engineering Society 36.6 (1988): 443-456.),which was conducted in true laboratory settings, and this is a much more precise examination of the subject. I describe their findings on page 3 of this article. If you really want to know how audible harmonic distortion is in bass frequencies, look at table 2 in that article.

Without getting the paper, it looks like they were researching threshold of detection. That was their goal. Now you add the actual program material, what Axiom may have added, the outcome would be different, much higher I would imagine.
I seem to have it in my library so I will read it again to see how the testing was set up. Thanks.

ps:
This was Axiom's intent to uncover about distortion:
but it's hard to imagine what those figures represent under real-world listening conditions. Will we hear it with music? How much distortion can we tolerate or even detect?