What's the technical term for bosso's style of sub?

[Warrant]

They're not iso's, are they?

[BOBinGA]

Don't make me Google it. Do you have a URL link?

-Bob

[Warrant]

http://web.mac.com/bossobass.com/iWeb/Site/Welcome.html

[cbark]

They're not iso's, are they?

No, it looks like they are standard sealed stuff, but I know nothing about them. Nice cabinets, made to be "out for show".

[Bent]

dual driver sealed with big power to accomodate small(ish) enclosures, and it looks like active EQ.

And nope - I don't think isovaric, but I can't see the second driver

[Undefinition]

Not isobaric; dual-opposed. Works sweet for subwoofers! Tons of bass, and you can barely feel the thing moving.

[BOBinGA]

That guy's insane. He surely has no hearing left. Plus I find his claim of 6 hz at 115 db dubious at best. That would take a foot of displacement even for two 15s.

-Bob

[Bent]

IIRC, JJ's AV15's don't have "that" much displacement compared to the old Adire Tumults and Brahmas (which Bosso used to use).

[nels07]

i only see him mention 115 db peaks not 115 at 6hz

[BobEllis]

technical term - Hype?

[BOBinGA]

Sorry, I read too quickly. I saw 6 hz and 115 db within a sentence of each other. I'll read more carefully next time. Since Bosso was a little short on displacement specs, I ran a quick sim in WinISD. Bosso claims 86db at about 6hz. With two 15s, you can indeed achieve this with an LT circuit, but the displacement is already up up to 14mm. If you go up to just 90 db at 6 hz you need 24mm displacement and 500watts. Maybe that is doable, but I don't think those woofers have 24mm Xmax.

I don't know, but I still see more hype than substance there.

-Bob

[Warrant]

Maybe read some of his stuff on AVS sounds credible to a newbie like me.

[cjd]

Maybe read some of his stuff on AVS sounds credible to a newbie like me.

That's the problem (IMHO) with AVS -it sounds credible. Unfortunately a lot is borderline and every so often just plain wrong. Other times it is someone wanting to be someone so tey make a name for themselves with regular stuff. Not bad stuff (bosso isn't doing the impossible after all) necessarily. But AVS is a hype machine. And sometimes stuff gets away from someone -they didn't expect the popularity and it carries them away.

Some good basic stuff in this case, add hype and stir...

[BobEllis]

Don't forget a healthy splash of commercial self interest as he will soon be offering a commercial model.

[bossobass]

Been a while since I've visited this forum.

I just wanted to stop in to mention that I don't do hype. After 50+ subs and enough tests against theory, it is what it is. Everything in my web pages is as accurate as technology and my simple observations allow for.

Attributing my posts and web info to hype actually offends me, but I'm a fair person. Please point out the hype, preferably backed by something of substance, and I'll be glad to help sift through the misunderstanding. 8)

As far as the Raven and Blackbird systems being "standard sealed stuff", I certainly am interested in seeing other such examples.

The ThruVent Cooling System is the only active driver motor conduction/convection cooling system that uses outside forced air I'm aware of.

The up/down driver firing configuration and its advantages in a corner loaded placement is the only such version I'm aware of and dates to 2002, when I built and tested one for the first time.

The top and bottom plate loading, designed to address ASD and increase output is the only such tested example I know of.

The stacking system of the Blackbird, designed to affect several performance parameters is the only tested example I know of. I'm not aware of any related publication of related test results, especially since I haven't yet published any of the results.

As far as my motivation for a decade of posting at AVS (and others), answering thousands of PMs and e-mails, writing manuals and a setup guide and including as much data as I have on a web site, all for free, being that I've discovered that I can make a name for myself with regular stuff: I disagree that much of my stuff is regular, I could certainly find ways to follow such a shallow pursuit that require far less effort and, well, it's just a silly notion.

Again, I would be glad to address any specific claims that what I post is hype (or any other derogatory verb).

Bosso

[bossobass]

Don't forget a healthy splash of commercial self interest as he will soon be offering a commercial model.

Really? Do you have any more details?

Bosso

[Bear]

Really? Do you have any more details?

Bosso

Something about this:

Image not available

Might lead a reader to a conclusion of there being a commercial interest. Something about the word "purchase" just has that effect on people. :T

[cbark]

You also quoted me, and put words in my mouth. The original poster asked a quick question, alignment. I answered. That's it. If it isn't sealed, I did note that I know nothing about them, but it seems that I was correct. Sorry to offend with using the word "standard". I just come to this board to either learn something or help somebody if I have the knowledge, that's it.

[bossobass]

Something about this:

Might lead a reader to a conclusion of there being a commercial interest. Something about the word "purchase" just has that effect on people. :T

Thanks for asking:

When I decided to build a complete new system, I decided to build more than I need to test various aspects of the design in-room, since there is no available related information to refer to.

I mentioned in my posts (sorry, I only post on AVS these days, as a rule, and can't send my intentions as a DIY sub builder to everyone on earth) that I would be selling off what I didn't need after the tests.

Since then, my hard drive crashed and I lost the ability to alter the web pages, as I lost all of the original files for the site.

All of the available Blackbirds were sold off before I even built them.

My only choice was to leave the web site up as it is until I built a completely new site, or take it down entirely.

I chose to leave it up.

To be perfectly honest, every time someone like Danley or Chase has said that I'm trying to sell subwoofers, I get dozens of inquiries. I find it a bit of a chuckle that anyone would try to sell subwoofers about which there is no information, no order page, no pricing, no payment method, etc.

Nevertheless, some day I may make them available, but, if and when I ever do, they will not be sold ID, and I would stop posting in any DIY sub forums.

Hope this helps. :T

Bosso

[Warrant]

Well guys, he's here (BTW, thanks) I am a little surprised that you bothered to comment. While not the internet police I hope that in this thread we can avoid the need to interpret opinion and provide facts with a minimum of hyperbole.

I like this site and the support it provides me but I am also a member at AVS and don't see (or ignore) board flames, as they're probably best left to the l33t or majic boards.

Bosso since you came over I was wondering, is cooling critical to accurate reproduction in a home theater application for a two hour movie such as Star Trek or Serenity or The Blue Man Group's Complex DVD?

I would post this over there but with the high speed, low drag environment, I fear it would get lost quickly and despite the suspicious nature of some, I do like this place. As I want to build them as end tables the drivers would be in a horizontal plane, would that impact the stability and results your system portrays?

MTF

Thanks.

[brent_s]

Sorry, I read too quickly. I saw 6 hz and 115 db within a sentence of each other. I'll read more carefully next time. Since Bosso was a little short on displacement specs, I ran a quick sim in WinISD. Bosso claims 86db at about 6hz. With two 15s, you can indeed achieve this with an LT circuit, but the displacement is already up up to 14mm. If you go up to just 90 db at 6 hz you need 24mm displacement and 500watts. Maybe that is doable, but I don't think those woofers have 24mm Xmax.

I don't know, but I still see more hype than substance there.

-Bob

Easy enough to verify. Xmax=23mm, Xsus=32mm. Larger Sd than the old Brahmas (smaller surround), but a little less spec'd Xmax. Bosso's were supposedly tweaked in some way so they may have even a bit more juice.

John's been in the driver design/build game for a long time...good stuff there; unfortunately a lot of bad luck with suppliers and he's a one man show. FWIW, John/AE also builds some of Seaton's drivers and probably others we don't know about.

-Brent

[Warrant]

That's the problem (IMHO) with AVS -it sounds credible. Unfortunately a lot is borderline and every so often just plain wrong. Other times it is someone wanting to be someone so tey make a name for themselves with regular stuff. Not bad stuff (bosso isn't doing the impossible after all) necessarily. But AVS is a hype machine. And sometimes stuff gets away from someone -they didn't expect the popularity and it carries them away.

Some good basic stuff in this case, add hype and stir...

Hey, you, get out of this thread, you have drawings to do and I have rough cut wood waiting for your stamp of approval. My wife is tired of me leaving piles of wood lying around.

Did the humour come across? ops:

[bossobass]

Well guys, he's here (BTW, thanks) I am a little surprised that you bothered to comment. While not the internet police I hope that in this thread we can avoid the need to interpret opinion and provide facts with a minimum of hyperbole.

I like this site and the support it provides me but I am also a member at AVS and don't see (or ignore) board flames, as they're probably best left to the l33t or majic boards.

Bosso since you came over I was wondering, is cooling critical to accurate reproduction in a home theater application for a two hour movie such as Star Trek or Serenity or The Blue Man Group's Complex DVD?

I would post this over there but with the high speed, low drag environment, I fear it would get lost quickly and despite the suspicious nature of some, I do like this place. As I want to build them as end tables the drivers would be in a horizontal plane, would that impact the stability and results your system portrays?

MTF

Thanks.

Hi MTF,

If you look at Ilkka's and/or Charlie's test results, when the sub under test is fed a 30 second sine sweep at its max output capability, there is 3-4dB or more of compression noticed.

That's a lot of loss to compression in just 30 seconds.

It depends on the sub, the source and the crazy person behind the controls. In my experiences, movies, not so much except for the rarest of examples. But, there's lots of music program available with loud, one-note, repetitious
bass. When played at high levels, or near a subs max output level, it doesn't take long for heat to rob output.

Think of how long it takes a 100W light bulb to reach a temp that makes it impossible to touch. Then think how long it takes a 3" VC to reach extremely high temp with 3,000W. Only a few seconds. And, it always takes longer to cool than it did to heat up.

Wayne Parham posted some very informative test results of his passive cooling system that you might find interesting:

http://audioroundtable.com/PiSpeakers/messages/17684.html

An excerpt:

At 15 minutes, the magnet is pretty much heat soaked. Without a cooling device, it's about 165º - 170º Fahrenheit at the front pole piece. It actually rises to this level fairly quickly, over the course of a few minutes. But then the temperature rise is very slow, which is why I assumed it was done rising after 15 or 20 minutes.

Then again, since the speaker failed, I'd say 190º or 195º pole piece temperature probably marks its red line. Without the heat exchanger, we crossed this line in less than an hour and a half. With the heat exchanger installed, it ran two hours at a relatively cool 138º inside at its hottest point. The back of the magnet was barely warm, at under 115º. So the heat exchanger did a great job of holding motor temperatures down and preventing voice coil failure.

Bosso

[Warrant]

Unfortunately most of this stuff is over my head, all I want is an awe inspiring sub that doesn't spill my wine and represents value. At the moment that means two IXL 18.2.2 in 10 cubic feet sealed and opposed.

[Warrant]

WinISD is telling me that my qes qms qts failed edit; why its a direct copy of posted data>

[BOBinGA]

Since I started all this, I guess I should apologize for the "unfriendly" tone of this thread. I started with a somewhat unfriendly "Don't make me Google it" and later "That guy's insane. He surely has no hearing left" and then "I don't know, but I still see more hype than substance there".

Let me start by saying I was not familiar with Bosso and his work. When I looked at his Raven site, it sure looked like a commercial site complete with marketing names for simple techical terms we are used to. "Signal-shaper" instead of Linkwitz Transform circuit and "Driver-Vu" instead of glass top. Then Bosso described his listening room and equipment: 15,000 watts of amplifiers in a room no larger than my humble family room to run six speaker and four subs. This all seemed more than overkill. With all the marketing words and the power use of a small city, excuse me for being a bit sceptical.

But after Brent pointed out that the subs actually do have 23mm of Xmax, I realized that maybe some of this could have merit.

One of the reasons I post almost exclusively here is because the posters take the time to explain what what they've done and, more importantly, why. We never engage in flame wars and a flame war was not my intent at all. So I'll have to watch the tone of my posts better.

So let's get back to what this site does best - analysis. Bosso, if you want to describe your subs in detail, I would love to see it - just without the marketing and a lot more technical detail. Perhaps this is already over at the AVS forum, but I don't visit there very often and a good link would be welcome.

-Bob

[exojam]

Bob,

Here is a thread on the Ravens from over on AVS. Some graphs are missing though.

http://www.avsforum.com/avs-vb/showthread.php?t=1109708&highlight=raven

James

[Bear]

Thanks for asking:

When I decided to build a complete new system, I decided to build more than I need to test various aspects of the design in-room, since there is no available related information to refer to.

I mentioned in my posts (sorry, I only post on AVS these days, as a rule, and can't send my intentions as a DIY sub builder to everyone on earth) that I would be selling off what I didn't need after the tests.

Since then, my hard drive crashed and I lost the ability to alter the web pages, as I lost all of the original files for the site.

All of the available Blackbirds were sold off before I even built them.

My only choice was to leave the web site up as it is until I built a completely new site, or take it down entirely.

I chose to leave it up.

To be perfectly honest, every time someone like Danley or Chase has said that I'm trying to sell subwoofers, I get dozens of inquiries. I find it a bit of a chuckle that anyone would try to sell subwoofers about which there is no information, no order page, no pricing, no payment method, etc.

Nevertheless, some day I may make them available, but, if and when I ever do, they will not be sold ID, and I would stop posting in any DIY sub forums.

Hope this helps. :T

Bosso

If you are getting dozens of unnecessary inquiries, you can download your files from the host, make edits, and replace them. It's a few minutes to a few hours. In fact, in looking through your HTML code, I noticed that you actually only need to edit the one PNG file I linked here. About five minutes of work, round trip, and it will save you from these "accusations".

[BOBinGA]

Thanks for the link James. I've started reading it and it is missing a lot of pictures like you said. But it is interesting.

-Bob

[bossobass]

If you are getting dozens of unnecessary inquiries, you can download your files from the host, make edits, and replace them. It's a few minutes to a few hours. In fact, in looking through your HTML code, I noticed that you actually only need to edit the one PNG file I linked here. About five minutes of work, round trip, and it will save you from these "accusations".

Thanks. What I was initially told is that I couldn't edit the files since I lost them, but what they meant to tell me was that I couldn't edit them in my iWeb app.

I did finally track down the hosted files and deleted the offensive text.

Bosso

[Bear]

Thanks. What I was initially told is that I couldn't edit the files since I lost them, but what they meant to tell me was that I couldn't edit them in my iWeb app.

I did finally track down the hosted files and deleted the offensive text.

Bosso

It's still there. You may want to just delete the relevant image file.

[AdelaaR]

15.000 watts?
Actual watts?
Bobinga called it "overkill" but I would classify this as "way beyond overkill".
I have thrown parties with almost a hundred people on 2x25 Watts and nobody was complaining the music wasn't loud enough.
But hey ... if anybody wants to have 15.000 watts in a house just to prove it can be done ... sure
There are some people a few villages from here who are christmasnuts and they have 15.000 watts of christmas lights on their house every year. The couple even stands outside wearing silly christmas costumes and handing out liquor and everything. To keep 15.000 watts going and still be able to turn the microwave on, they had to let the electricity company install new cables and a new industrial meter ... that alone cost them thousands of dollars.
To each his own I guess.

[A9X]

15.000 watts?
Actual watts?
Bobinga called it "overkill" but I would classify this as "way beyond overkill".

Why? Someone who can do it and is interested in it chooses too. There are 16 15" 1kW rated drivers in the stacks so it's not excessive. You also need to consider that amp power is relatively cheap especially in the US.

Looking at the materials cost, drivers, amps, EQ and materials, I doubt he'd have more invested in his bass rig than a single JL Audio Gotham ($US12k) and his system would kill it in terms of actual output. If you want to go very deep, each octave extra needs 4x the volume displacement and with smallish sealed subs, that means power.

I have thrown parties with almost a hundred people on 2x25 Watts and nobody was complaining the music wasn't loud enough.

having run PA systems for decades in homes and the typical small pub venues we have here, I find the 2x25W and loud enough dubious.

But hey ... if anybody wants to have 15.000 watts in a house just to prove it can be done ... sure
There are some people a few villages from here who are christmasnuts and they have 15.000 watts of christmas lights on their house every year. The couple even stands outside wearing silly christmas costumes and handing out liquor and everything. To keep 15.000 watts going and still be able to turn the microwave on, they had to let the electricity company install new cables and a new industrial meter ... that alone cost them thousands of dollars.
To each his own I guess.

I'm also a disliker of stupid Xmas displays, but try to understand the difference in load between a whole lot of lights, basically on constantly, to the peak to average ratio of even deep LF content in movies. How often in a movie are you going to get 0dBFS at deep LF, and how long are they going to last? Now average that over the duration of the movie and compare it to the lights.

[bossobass]

Why? Someone who can do it and is interested in it chooses too. There are 16 15" 1kW rated drivers in the stacks so it's not excessive. You also need to consider that amp power is relatively cheap especially in the US.

Looking at the materials cost, drivers, amps, EQ and materials, I doubt he'd have more invested in his bass rig than a single JL Audio Gotham ($US12k) and his system would kill it in terms of actual output. If you want to go very deep, each octave extra needs 4x the volume displacement and with smallish sealed subs, that means power.
having run PA systems for decades in homes and the typical small pub venues we have here, I find the 2x25W and loud enough dubious.
I'm also a disliker of stupid Xmas displays, but try to understand the difference in load between a whole lot of lights, basically on constantly, to the peak to average ratio of even deep LF content in movies. How often in a movie are you going to get 0dBFS at deep LF, and how long are they going to last? Now average that over the duration of the movie and compare it to the lights.

Thank you. 8)

So many people have a misunderstanding of how it works. Watts (and subwoofers in general) are not strictly about SPL. A single stack of 8-15s is roughly 98dB 1W/1M. The stack coasts along with most source, even at reference level playback, in my HT.

If reference level requires 115dB peaks, plus redirected bass from the satellites set to 'small' = approximately 121dB peaks, the stack will require around 300W to achieve that for all frequencies from the knee up to cross with a touch of headroom.

Since the sealed system rolls off below the knee at 12dB/octave, signal boost is required to alter that response to work with room gain to produce a flat response at the listening position to 3 Hz, the bottom of the Dolby spec of 3-120 Hz.

In my room, the Boost, which is gradual from the knee to about 28 Hz and remains at full boost from there down, is ideal at +10dB.

300W with +10dB of boost requires 3,000W for frequencies below 20Hz. If you run the subwoofer at +3dB hot, which many people do, you now require 6,000W for those infrasonic transient peaks.

As you've correctly pointed out, those sorts of peaks are usually momentary.

The amplifiers are each fed by a dedicated 30A home run. Doing the simple math, 120V*30A is 3,600W continuous. The amplifiers can provide up to 8,000W burst for transients, but will quickly settle down to 3600W maximum continuous output.

This sort of amplification is not uncommon (at least in manufacturers specs). The Gotham you mentioned claims 3800W RMS, and it's high pass filtered at 20 Hz. The new Paradigm flagship claims 3,000W RMS and 7,500W peak, and that's a single driver sub.

Those momentary (and sometimes not so momentary) infrasonic effects exist on many, many DVDs and BRs. I'm not aware of anyone who boasts faithful reference level playback of those soundtracks with no compression, audible distortion or artifacts.

Here is just one recent example of a seriously difficult effect for a subwoofer to accurately reproduce captured on SpectrumLab. The scene is at the end of How To Train Your Dragon, where the big dragon crashes to earth. One graph was made from a direct feed into the interface from the DVD players SW output jack. The other graph is made by the subwoofers playing into a microphone placed at the listening position:

Image not available

If someone knows how to do that with 25 watts, he or she should be on an island counting gold from the sale of such an invention, and I'd surely like a link to the details.

Actually, a single stack, 1 of my new tracking digital switch mode supply amplifiers and the signal shaper (no, it's not a simple Linkwitz Transfer bi quad filter), all materials, less labor, could probably be purchased and built by an industrious sort for under $4k and would handle playback of any source crushingly better than the Paradigm flagship or the Gotham.

Again, A, thanks for the post.

Bosso

[AdelaaR]

I never said 15.000 watts is overkill in any situation.
Entire IMAX theatres with a thousand people run on 15.000 watts and rightfully so, but to have 15.000 watts in an average house is way beyond overkill.
You speak of 121dB peaks ... those are very bad for your hearing and they might just be the reason why you need to crank the volume up so loud.
I even wonder how you keep your house from falling apart with that kind of power.
How did I throw entire parties on 2x25 watt? With a vintage Pioneer SA-6300.
If you have one of these ... try it

[ThomasW]

You speak of 121dB peaks ... those are very bad for your hearing 0

We're talking a subwoofer's passband not fullrange. 121 dB peaks of low bass doesn't damage hearing..

[AdelaaR]

Indeed. My bad

[Bear]

We're talking a subwoofer's passband not fullrange. 121 dB peaks of low bass doesn't damage hearing..

I'd like to see some backing information on this if you are talking about >120dB within the audible range. Weighting will also matter here, but I take that as a relative given. Total exposure of 15 minutes per day or less at 115dBA requires noise mitigation, according to OSHA.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10625#1926.52%28d%29%281%29

[A9X]

I'd like to see some backing information on this if you are talking about >120dB within the audible range. Weighting will also matter here, but I take that as a relative given. Total exposure of 15 minutes per day or less at 115dBA requires noise mitigation, according to OSHA.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10625 #1926.52%28d%29%281%29

Factor in the A weighting curve and it's a non issue.

[Bear]

Factor in the A weighting curve and it's a non issue.

The OSHA regs are A-weighted values. 115dBA is a lot of SPL. If you are talking unweighted, then this is borderline irrelevant. You want to deal with perceptually flat, not really physically flat if you are talking about how we here. If you are talking about infrasonics, and you want a "rumble in the tummy", then something like a Bass Shaker still seems like a better way to go for infrasonic signals to me (smaller, more efficient, physically moves you, etc.).

[krips]

So if you experiance very high levels of bass, but they are not audible to you (say 10hz) it does no damage to your hearing? I thought since it was still made of pressurized waves it would do damage.

[cbark]

So if you experiance very high levels of bass, but they are not audible to you (say 10hz) it does no damage to your hearing? I thought since it was still made of pressurized waves it would do damage.

If we use 20Hz as a reference, and use the supplied A-weighted graph above (used by OSHA because this is the closest representation of how a human hears sounds) to calculate a 120dBA sound level, the sub would need to sustain a continuous sound pressure level of 170dB to be perceived as a 120dB level. The continuous is an important aspect of this level, as well as in the eyes of OSHA. Continuous being defined as multiple instances within 1 second. Music is very dynamic, and the peak level readings people sometimes throw out are by all means not continuous.

Hope this helps.

[Bear]

So if you experiance very high levels of bass, but they are not audible to you (say 10hz) it does no damage to your hearing? I thought since it was still made of pressurized waves it would do damage.

Theoretically no, but then, you are only really feeling it, not hearing it anyway. A subwoofer system like this will pressurize everything in the room equally (absent the effects of standing waves and odd geometry). Given the tactile nature of the experience, the question some (me) might offer is why go to the trouble of vibrating everything in the room with infrasonics when there are dedicated drivers (e.g., shakers) that will give you a more targeted experience. It's not quite the same effect, but the question is what your goal is and whether it is worth the expense.