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Voice coil help

Deerhunter

Well-Known Member
I recently made a comment about PSA Subs and how they kick ass! It was a video on YouTube

Dragon51 PSA has a 3 inch voice coil, begging for warble and excursion compared to an 8 inch voice coil in the SVS. I'll do the SVS all day long.


Does that make it better than the PSA ?
 

Flint

Dog Faced Pony Soldier
Superstar
Does that make it better than the PSA ?
No.

In fact, it is extremely difficult, expensive, and complicated to get a greater diameter voice coil to operate as linearly as a narrower voice coil.

Basically, just like any mechanical device, getting very large components to work at extremely tight and consistent tolerances is VERY difficult when smaller components could accomplish the same practical results. One of the reasons large voice coils tend to be better isn't inherently the size of the voice coil, but the more advanced engineering, manufacturing, and more robust components used. So, a designer has to find the right balance between cost, reliability, manufacturability, performance, and so on. If cost is no object, and the tolerances are comparable, a larger voice coil woofer will have higher magnetic gauss, greater motor strength, high power handling than a smaller voice coil woofer. However, the cost to produce a quality woofer rises exponentially as the diameter is increased - assuming you want the highest performance.

I have experienced high end subwoofer drivers with 2" voice coils which could completely wipe the floor with okay grade woofers with huge 6 inch or 8 inch voice coils. I've also seen the opposite. Ultimately, that spec means absolutely nothing without taking into account all the other aspects of a woofer's design and its intended application. Just like peak to peak excursion became a thing in car subwoofers about a decade about, without any consideration to actual acoustical performance. this idea that a larger voice coil is better, just because it is larger, is a false concept.

As a general rule, assuming the quality of components and manufacturing is identical, if a two 15" woofers sell for $500 each, the one with the larger voice coil is very likely not as good as the one with the smaller voice coil. Why? Because it should cost significantly more to get the same primary performance characteristics (sensitivity, Bl, Fs, P-to-P excursion, linearity, and such) from a larger voice coil than from a smaller one.

We all get the idea that one speaker with a 15" woofer might not perform as well in the bass as a much higher quality and costlier speaker with an 8" woofer, the same applies to the components which make up the drivers, like voice coil, magnets, surrounds, and so on.


So, look at the real world performance of a subwoofer, not the size of the voice coil, the peak power handling, or physical size.
 

Deerhunter

Well-Known Member
Flint

Once again thank you. I almost want to reply to that person and all him out. But I won't, I will rest with the knowledge he knows noting about what he speaks.

I asked, the man the myth the legendary Flint!
 

bmwuk

Well-Known Member
Flint

Once again thank you. I almost want to reply to that person and all him out. But I won't, I will rest with the knowledge he knows noting about what he speaks.

I asked, the man the myth the legendary Flint!
We all gain something from each other in knowledge and I am thankful to all of you for that. And the coolest thing since back in the day is @Flint explains it well without being arrogant or condescending. Same with all the folks here
 

Flint

Dog Faced Pony Soldier
Superstar
We all gain something from each other in knowledge and I am thankful to all of you for that. And the coolest thing since back in the day is @Flint explains it well without being arrogant or condescending. Same with all the folks here
Thanks!!! I admit that too often my "know it all" attitude gets annoying. You guys are very patient with me.
 

Flint

Dog Faced Pony Soldier
Superstar
So, it appears SVS is using the new subwoofers from Peerless for their top of the line products, which is great:

Here's a link to an off the shelf 15" sub with similar features as the one used in the SVS 16-Ultra series, which come with 8" voice coils:
https://www.madisoundspeakerstore.com/subwoofers/peerless-stw-350f-188pr01-04-15-subwoofer/

While I cannot confirm this as a perfect match across the board, the use of three suspension points (two spiders and a surround), an 8 inch voice coil, and visually similar cone, surround, and frame, I am confident these are from the same designers as the SVS drivers.

So, what do you get? Well, the huge voice coil and added magnet mass increases power handling, motor linearity and Bl linearity. However, the added mass, lower motor strength, and necessity for triple suspension results in a lower sensitivity than most other hi-fi subwoofers designed for deep bass. So, to gain the benefit of high motor linearity, the woofer requires as much as 10x the power as other subwoofers of similar cost, size, and peak output capacity. So, you can use a similar priced subwoofer with a 3 inch voice coil with a max sustained power handing of 300 W to get 117dB at 25Hz, or you can use a subwoofer with an 8 inch voice coil with a max sustained power capacity of 3,000 W to get 115 dB SPL at 25Hz. One could argue the greater motor linearity of the less efficient woofer with a huge voice coil is a benefit, and I cannot dispute that, it is a little scary to me to think that I need 10x the power to get the same output in the room as the smaller voice coil subwoofer.

Another advantage of the huge voice coil sub, which I am certain SVS is counting on, is the fact it doesn't require as huge an enclosure to get an ideal performance for the most critical operating range - which for HT use is between 30Hz and 60Hz. Being a super-nerd, I tend to want the best performance at 20Hz and lower which then assumes very good performance in the 30Hz to 60Hz range, but that's my nerdy character. Most users don't really appreciate stunning performance below 25Hz as most users have listening rooms which resonate like a drunken bastard below 40Hz anyway. So a tighter, cleaner, smoother subwoofer in the "subsonic" frequency range is useless to a good 90% of customers for aftermarket subs like this. Hell, I've recently discovered that many serious and well-intentioned "audiophiles" with some of the best gear on Earth tune their subwoofers on their "reference systems" 10dB to 25dB too loud. They energize their noisy, lively, resonant rooms to much in the bass, they cannot turn their systems up enough to appreciate the other 9 octaves of sound properly. It is sad.

So, if SVS is using these very good Peerless made drivers, I openly admit they are very good. However, I could argue they are sacrificing perfection across the entire range for improvements in box size and detriment in the super low subsonic bass and making those insanely huge 1,500 W amps absolutely necessary - which is fraught with their own risks (how many AC circuits do you need if you have a 7 channel Monolith amp and a couple SVS 16-Ultra subwoofers???).

So, it is all a game of "what works best for you" that makes this discussion incredibly complex.
 

Deerhunter

Well-Known Member
All very interesting stuff. Its incredible just how much you know about speakers about audio general. You make it sound so simple, like everyone should know this stuff.

As always thank you for your time.
 

Flint

Dog Faced Pony Soldier
Superstar
My last post on this topic, unless there are questions.

I found the press release on this woofer on my industry news site:
https://www.audioxpress.com/news/peerless-by-tymphany-launches-stw-350-15-hi-fidelity-subwoofer

The manufacturer's main claims which are unique to the huge voice coil are:
  1. Superior low-frequency performance in a smaller-than-traditional enclosure.
  2. Provides extraordinarily low power compression.
While the low power compression is desirable, the ability to use a smaller enclosure is merely a "good to have" feature to have when performance is the primary goal.

The other claims about this woofer (high power handling, high output, low distortion, etc.) are common for well made woofers.
 

Randy

Well-Known Member
Famous
So, it appears SVS is using the new subwoofers from Peerless for their top of the line products, which is great:

Here's a link to an off the shelf 15" sub with similar features as the one used in the SVS 16-Ultra series, which come with 8" voice coils:
https://www.madisoundspeakerstore.com/subwoofers/peerless-stw-350f-188pr01-04-15-subwoofer/

While I cannot confirm this as a perfect match across the board, the use of three suspension points (two spiders and a surround), an 8 inch voice coil, and visually similar cone, surround, and frame, I am confident these are from the same designers as the SVS drivers.

So, what do you get? Well, the huge voice coil and added magnet mass increases power handling, motor linearity and Bl linearity. However, the added mass, lower motor strength, and necessity for triple suspension results in a lower sensitivity than most other hi-fi subwoofers designed for deep bass. So, to gain the benefit of high motor linearity, the woofer requires as much as 10x the power as other subwoofers of similar cost, size, and peak output capacity. So, you can use a similar priced subwoofer with a 3 inch voice coil with a max sustained power handing of 300 W to get 117dB at 25Hz, or you can use a subwoofer with an 8 inch voice coil with a max sustained power capacity of 3,000 W to get 115 dB SPL at 25Hz. One could argue the greater motor linearity of the less efficient woofer with a huge voice coil is a benefit, and I cannot dispute that, it is a little scary to me to think that I need 10x the power to get the same output in the room as the smaller voice coil subwoofer.

Another advantage of the huge voice coil sub, which I am certain SVS is counting on, is the fact it doesn't require as huge an enclosure to get an ideal performance for the most critical operating range - which for HT use is between 30Hz and 60Hz. Being a super-nerd, I tend to want the best performance at 20Hz and lower which then assumes very good performance in the 30Hz to 60Hz range, but that's my nerdy character. Most users don't really appreciate stunning performance below 25Hz as most users have listening rooms which resonate like a drunken bastard below 40Hz anyway. So a tighter, cleaner, smoother subwoofer in the "subsonic" frequency range is useless to a good 90% of customers for aftermarket subs like this. Hell, I've recently discovered that many serious and well-intentioned "audiophiles" with some of the best gear on Earth tune their subwoofers on their "reference systems" 10dB to 25dB too loud. They energize their noisy, lively, resonant rooms to much in the bass, they cannot turn their systems up enough to appreciate the other 9 octaves of sound properly. It is sad.

So, if SVS is using these very good Peerless made drivers, I openly admit they are very good. However, I could argue they are sacrificing perfection across the entire range for improvements in box size and detriment in the super low subsonic bass and making those insanely huge 1,500 W amps absolutely necessary - which is fraught with their own risks (how many AC circuits do you need if you have a 7 channel Monolith amp and a couple SVS 16-Ultra subwoofers???).

So, it is all a game of "what works best for you" that makes this discussion incredibly complex.

Yes, Thank you Flint for that educated, easy to read, and well thought out response.

Keep in mind some of those guys also build stuff just to sell, even though 90% of users cant and wont appreciate performance in the lowest octaves, if they can convince their potential customers that a larger voice coil and a smaller enclosure is what they need they have succeeded.

I truly believe that a lot of companies in the audio biz (especially relating back to the car audio stuff you referenced) is made just because someone in the company says they can market and sell it.

But again, great post and thank you again.
 

Flint

Dog Faced Pony Soldier
Superstar
Yes, Thank you Flint for that educated, easy to read, and well thought out response.

Keep in mind some of those guys also build stuff just to sell, even though 90% of users cant and wont appreciate performance in the lowest octaves, if they can convince their potential customers that a larger voice coil and a smaller enclosure is what they need they have succeeded.

I truly believe that a lot of companies in the audio biz (especially relating back to the car audio stuff you referenced) is made just because someone in the company says they can market and sell it.

But again, great post and thank you again.

I am certain the 16-Ultra is one hell of a subwoofer. My entire point of this discussion is to clear up that an 8" voice coil alone doesn't make these subwoofers spectacularly better than any other subwoofer of similar quality.
 

Randy

Well-Known Member
Famous
I am certain the 16-Ultra is one hell of a subwoofer. My entire point of this discussion is to clear up that an 8" voice coil alone doesn't make these subwoofers spectacularly better than any other subwoofer of similar quality.
Right, I got that. I was merely stating that sometimes audio companies may build a sub with a driver with an 8" voice coil (remembering the excursion wars in car audio) simply because they can market it and sell it over their competitors 3" voice coil, not because it makes any sense from a performance perspective.
 

heeman

Well-Known Member
Famous
Bose comes to mind..................

With respect to being a speaker marketing machine, also Monster Cable in the accessory segment.
 

Flint

Dog Faced Pony Soldier
Superstar
Yes, I can see the engineers at SVS choosing those drivers for good reasons, but then the marketing department making the Voice Coil the primary selling point.

It isn't that different from the "power handling WAR" of the 1980s where the only thing that mattered was "How Many Watts It Has!!!" Or when the amplifier world became completely consumed by the current capabilities of every amp launched. The CD market went crazy with "Oversampling" wars.

Ultimately, these small things do matter, but they should not be the sole differentiator between products NOR should these things be the only thing the buyers care about.
 

heeman

Well-Known Member
Famous
To add......................everything being relative, we buy new, upgraded equipment and swear it sounds or looks better, then what it replaced, but to what criteria???

When was the time when someone bought new gear and said "crap did I screw up, these new speakers sound awful!".

Well, I think @Zing did, that with his Mackies.

I swore my MB Quarts sounded better than my Studio 60's and that my PSA MTM 210's sounded better than my MB Quarts.

How would I truly know that a Subwoofer upgrade would sound/perform significantly better???????

Or replacing my C1's with some custom designed speakers??

At first I wasn't all that thrilled with the C1's...................

Sorry for the rambling................................
 

Zing

Retired Admin
Famous
Well, I think @Zing did, that with his Mackies.
That's a hell of a memory you have!

A few points in the spirit of full disclosure. While true, I was not at all happy with the Mackies in my old room at the old house, and did in fact return them, I was pleasantly surprised how good they sounded in Towen's room.
 

heeman

Well-Known Member
Famous
That's a hell of a memory you have!

A few points in the spirit of full disclosure. While true, I was not at all happy with the Mackies in my old room at the old house, and did in fact return them, I was pleasantly surprised how good they sounded in Towen's room.
Yes, Towens and Morys Home Theater.......
 
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