Choosing an amp for a subwoofer

audioarcher

Well-Known Member
May 6, 2012
1,396
51
970
Seattle area
Dear friends: I read it the whole thread learning about. If I want to add subs at any audio system with passive main speakers I will go for an active/powered subwoofers.

Active/powered subs are a matched integrated subs system where almost all are in control. When we are choosing for an amplifier ( any ) to mate it to a passive subs we and the amp have control over almost nothing and this means: higher distortions.

IMHO, any passive speakers ( including full range ones. ) benefit on added active/powered subwoofers and it does not matters the room dimensions.

This is something that I writed time ago but I think I can use it to explain my opinion about:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1117893153&openflup&27&4#27


additional there is something that we as audiophiles have to take care when we add or are going to choose " which subs are for my system? " and is the subs THD level.
Example the JL subs has around 10% THD at 20hz where the Velodyne has only 0.5% THD at 20 hz.

why that important difference between the JLs ( and several other subs. ) and Velodynes? because almost no one of those subs really has control on the movements of their woofers in all playback condition where the Velodyne sense aroun 16K times each second the woofer excursion to control it remaining at no more than 0.5% THD. Velodynes has a very good system that control each single woofer characteristic on normal or overloaded conditions.


Regards and enjoy the music,
R.

I agree. I never understood why people make expensive full range speakers with no way to adjust the bass response except room placement. It's just not a complete design IMO.
 

silviajulieta

Well-Known Member
Jul 6, 2010
364
15
323
México city. rauliruegas@hotmail.com
I agree. I never understood why people make expensive full range speakers with no way to adjust the bass response except room placement. It's just not a complete design IMO.


Dear Audioarcher: We can't saying for sure but seems to me that busine$$ is part of the subject as is the audiophile/customers ignorance level. In passive full range speakers maybe 2/3 of its price goes or belongs to those 1.5/2 bottom octaves, these are the most expensive ones. With out those octaves the manufacturers can't charge you: 100k+ big dollars in the price.

The real " problem " is that a pair of well designed monitors alond a pair of self powered subwoofers can outperform the magabucks full range passive speakers for only a small price fraction but this alternative/solution is not very good looking for we customers because our ignorance level on what's important down there: why the existence/main target of speakers and how achieve the best way that main targets?

I want to think that that's part of the AHEE convenience and not because ignorance level of the speaker manufacturers too...

I learned that the main target to add subs in an audio system is not to go deeper on the bass or quantity or that " boom boom "/ w/o sense but to improve both: the quality performance level of the system main passive speakers and to improve the quality performance level of the bass management that IMHO is where in a home audio system belongs the music: the foundation reside down there, as better ( better means lower distortions. ) the audio system bass management as better the overall audio system quality performance level. No doubt about.

Speaking of passive speakers manufacturers the AHEE " rules " are: not speaks or give measurement on their speaker different kind of distortions either: THD or IMD at different SPL. Take a look to passive speakers designs manufacturer specs and you can't find out no figure about.

Here are Wilson owners: can any one of them share those distoprtions measurements ? Some one pointed out here that his speakers goes down 3-7 hz and we have to questioning our self: so what, is it important? why we need a speaker goes so down? which are the distortion levels during playback at 120 db SPL? the owner knows that at that low bass exist several electronic artefacts coming from the amp and " somewhere " that could be amplified by the speakers at the fundamental and the harmonics causing deep distortions that contaminate everything? , could be " nice " to have a system that goes down to 3hz but IMHO is more important to know its distortion levels.

Btw, speaking of LPs I think that the recording with the lower bass notes was the Telarc 1812 Overture at: 8hz, I think that 3-7hz speakers can honor that so low frequency range.

As everything in audio in this important audio link each one knowledge level is the key to success level. Numbers/measurements makes no sense if we can't understand its meaning or if we don't measures what's important or even worst: if we don't know how it mesure it.

If an active/self-powered subs involve several problems that end as distortions a passive subs only increment in an exponential way those distortion problems because it does not matters what powerful will be the amp to mate that passive subs problem is that: we can't control nothing, we are at random with higher distortions. Amp power in this regards means almost nothing.

In a home audio system what we need is a self powered subwoofers not passive ones. IMHO what we have to look down there is quality not quantity, in this regards when we can I think that when choosing subs we can have some advantage with sealed/acoustic suspension designs over ported ones because the formers normally has lower distortions.

Regards and enjoy the music,
R.
 
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silviajulieta

Well-Known Member
Jul 6, 2010
364
15
323
México city. rauliruegas@hotmail.com
Dear friends: Looking to the subwoofer forum I can see that almost no one is interested on this critical subject. Almost all the threads are old ones and I wonder why because : I insit the whole subject is critical to maximise the MUSIC enjoyment through a home audio system.


Reading here and there in this forum I found out that for some persons exist a toatlly misunderstood on the why's about the use of subwoofers to enjoy MUSIC in a two speakers / stereo ) systems.

But even the technical experts posts speaks almost nothing about distortions: measured distortions in subwoofer it self. The posts are " concentrated " on number of subs and room position that are truly important subjects. In room flat frequency response is always an " ideal " target but maybe we are more sensitive to distortions levels and almost no one cares about and almost no one cares of distortions not only at each system audio link but even overall distortions in the system

Reading some posts of some of you I can see that as I said MUSIC does not exist and I wonder where some of you learned or were educated in audio/MUSIC?

In any case, true advantages on seamless integration of two powered subs in true stereo fashion:

- lowest speaker system Harmonic Distortion and IMD if choosed the right powered subs.
- better low bass quality.
- deep/and lower bass frequency response.
- right low bass system/room quantity.
- better system mid bass, mid range, hf, soundstage, etc quality performance.
- higher system SPL/headroom with lower overall distortions.
- better amplifier main speakers performance.
- better main/satellite speakers quality performance too.
- better speaker system room integration.
- better system bass management.
- better, better, better, etc, etc.

this is what I learn about: a full and better home audio system quality performance with more real MUSIC information with the lowest distortions.


Regards and enjoy the music,
R.
 

NorthStar

Member
Feb 8, 2011
24,305
1,323
435
Vancouver Island, B.C. Canada
I do agree with you Raul, and we don't examine the 'plate amps' used by subwoofer's manufacturers.

Most audiophiles simply trust and rely on them powered sub designers. People love their Phantom, Gotham, etc. powered subs.
...Bassis Profundis Extremis ....

But if someone comes around and shows us the deficiencies of them subs, and which other plate amps could be better used in them (or separated amps with passive subwoofers); we're all ears and eyes.
We love our measurements, we love our dedicated and treated rooms, and we love parametric equalization where it counts the most.

* Everything you just mentioned in your above two posts, and more, I'm with you.

Cheers, Best regards, & Enjoy the Music,
Bob
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
...BTW, did you ever listen to the X2 paired with the Wilson Thor subs in a system having a similar quality to Steve's one?

I have seen many of the comments about the recent Wilson demonstration of the Wilson XLF + dual Thors. Have you heard X2s + Thors? Most curious as to how much of a step up in scale/effortless you get from such a combination...particularly in massed strings, etc (as opposed to simply down low).
 

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