I have really been having trouble getting reliable bass integrated into my sytem. I built a TC sounds LMS 18" sealed sub only to blow it due to too much power. And after many conversations about how the woofer has too much power to ever run it safely by limiting its excursion throw by putting it in a small enough box ,I am looking at different methods. So I am seriously contemplating the idea of an infinite baffle system.
I have a small space of about 7000L (250cf) behind my LCRs. I have been doing my research and came across This Web Page
On question #6 it states,
The drivers I have been looking at are here
Now with the above info, this gives about 5 times the total Vas of 4 X 18" drivers.
My question to the experts is ,
#1, Would I be better to stick with 2 18"
#2, Or would having 5 times the total Vas be fine?
So would a true infinite baffle system be the way to go or the compromise to make sure I get enough bass for the low frequencies?
My room is about 3000cf with all 4 walls ,floor and ceiling solid 12" concrete.
So in this kind of situation will what I am looking at be viable or even desirable?
I have a small space of about 7000L (250cf) behind my LCRs. I have been doing my research and came across This Web Page
On question #6 it states,
The drivers I have been looking at are here
Now with the above info, this gives about 5 times the total Vas of 4 X 18" drivers.
My question to the experts is ,
#1, Would I be better to stick with 2 18"
#2, Or would having 5 times the total Vas be fine?
So would a true infinite baffle system be the way to go or the compromise to make sure I get enough bass for the low frequencies?
My room is about 3000cf with all 4 walls ,floor and ceiling solid 12" concrete.
So in this kind of situation will what I am looking at be viable or even desirable?
The concept of "room gain" is not applicable for any room I ever heard of except possibly yours! Might be the first time I ever thought it counted in the design mix.
You use all kinds of slippery words. Frankly, no reader here could guess what you mean by "too much power", "low frequencies" and so on.
There's no more perfect (and feasible) enclosure, in almost all respects than a large box - big enough not to raise your driver resonance but with enough negative feedback (AKA "air spring") to keep clean and avoid self-destruction and never not works (that is, never have to tune after gluing it together.
The downsides are size and maybe can't be moved to better location in room. That may be a critical shortcoming in a resonant concrete room.
It used to be thought that 15 inch drivers, perhaps used in multiples, are optimum size for moving enough air but not too gross as a precision cone and mechanical assembly.
Ben
You use all kinds of slippery words. Frankly, no reader here could guess what you mean by "too much power", "low frequencies" and so on.
There's no more perfect (and feasible) enclosure, in almost all respects than a large box - big enough not to raise your driver resonance but with enough negative feedback (AKA "air spring") to keep clean and avoid self-destruction and never not works (that is, never have to tune after gluing it together.
The downsides are size and maybe can't be moved to better location in room. That may be a critical shortcoming in a resonant concrete room.
It used to be thought that 15 inch drivers, perhaps used in multiples, are optimum size for moving enough air but not too gross as a precision cone and mechanical assembly.
Ben
Last edited:
Hey Ben,
What I mean by too much power is that I literally fed about 8000 watts to the TC sound sub. But after many conversations I have come to the conclusion that the woofer is too powerful for any enclosure, and me being not that informed in subs, I could not control it at all without breaking it.
So an IB sub could be the better path for me.
Hi JapanDave,
You can answer that question in Hornresp, basically once you get past 2x Vas the low end gains are quite minimal. I'll attach a Hornresp Input screen and two SPL comparisons Vas 1 v. 5 and 5 v. 10 (you can enter the data for your driver into Hornresp, and get whatever additional simulations you are looking for).
Regards,
You can answer that question in Hornresp, basically once you get past 2x Vas the low end gains are quite minimal. I'll attach a Hornresp Input screen and two SPL comparisons Vas 1 v. 5 and 5 v. 10 (you can enter the data for your driver into Hornresp, and get whatever additional simulations you are looking for).
Regards,
Attachments
It is hard to "forget" a ridiculous claim.
Perhaps you should return to this forum when you have done your homework and are prepared to ask others to take time for a serious discussion.
Ben
You guys are way to hard on Dave. Personally if I owned my own home I'd go with an infinite baffle sub system. I suspect matching to your main system might be more a matter of what frequency and slope you are using to tie into your main system. It's also hard to make good recommendations without knowing more about what your main speakers are. I don't know a thing about the drivers you linked but you might also take a look at Audio Elegance they make some fine drivers.
We are trying to answer a question without information on end result parameters.
at a minimum:
what spl requirements?
What lower cutoff?
What power is available? Apparently 8kw!
also,
how many drivers are in the design?
size of listening space?
volume set aside for enclosure? 250cu ft.
Design prejudices? No ported/TH etc.
Program material? Movies obviously.
Out of curiosity, what was the situation you set up to destroy such an obviously capable driver?
at a minimum:
what spl requirements?
What lower cutoff?
What power is available? Apparently 8kw!
also,
how many drivers are in the design?
size of listening space?
volume set aside for enclosure? 250cu ft.
Design prejudices? No ported/TH etc.
Program material? Movies obviously.
Out of curiosity, what was the situation you set up to destroy such an obviously capable driver?
Ben I appreciate the help and I consider what I have done so far as the limit of my homework. I am all very new to all this and I don't what is the best system for me.
As for my ridiculous claim look at this thread on AVS, start at about post post #1869. (You could start earlier to see my previous questions) You see the events that unfolded for me to destroy the driver and then the following discussion about how the TC sounds 18" can't be put in a small enough box to control excursion. And with my inexperience I am likely to do it again, as some of the guys there stated that even 4000w's into that sub could be detrimental.
So please, can we get past this?
My room was designed by Dennis Erskine in my house that was already built. As you may have gathered by my handle I live in Japan and our house is designed to withstand earthquakes, hence having a house made of solid concrete and a basement with all 4 walls ,ceiling and floor with at least 12" concrete. The room has one door with is a solid sealed soundproof door of Dennis's design. So , yes you could probably call this room a true sealed room. Dennis had me add mountains of absorbers and treatments.
I am looking to integrate Quested Q210 which is claimed to have a response of 38hz-20hz +/- 2db at 123db at 1m. I am looking to cross them at about 60 to 70 hz , but this is tentative as I would like to see how the speakers measure with subs in place.
@ tb46, I am going to have to download hornsresp. Give me a bit.
I am not a SPL freak, I just want reference bass at 105 down 15hz and if it is possible maybe down to 10hz. Basically have enough headroom not to get into trouble with dynamic scenes in movies.
I only watch movies, no music.
As I said in the first post I was looking at 4 X 18".
The room size is in the first post, but to be more precise it is The room is 22.3' long 16' wide and 7.9' high.
As for power, I have no budget so anything is possible within reason.
For some reason I have never liked ported and I can't listen to horns, but I have never tried a horn sub if that makes any sense.
If there is anything else needed please let me know.
I looked at that, but it needs a true infinite baffle and although I could put a hole in the wall and use outside the house as an infinite baffle, but I can't due to the close proximity of the neighbors. so I canned that idea a while ago.
Sorry I did not answer this.
I have the amp on its own 30A outlet, how that enables a 14000w amp to get its its full power is way above my ability to understand or even explain how it does get full power.
The specs of the amp are below,
I am using the FP-14000.
It is rated at 14000 watts bridged at 4 ohm, which I did bridge the amp into the single driver. I am now aware that that was not a good thing to do.
If you want quite high SPL down to 10Hz you are going to need at least two, probably four of those drivers. If you want to use that space as a box then do so, you will be getting some room gain due to your solid and sealed room construction, so you probably won't need any bass boost to offset the roll-off. Any kind of ported box will not be easily possibly because you want to go to such low frequencies.
Looking at that thread on AVS you seem to have warped the voice coil due to overpowering. Putting it in a smaller box would only have made that worse.
Looking at that thread on AVS you seem to have warped the voice coil due to overpowering. Putting it in a smaller box would only have made that worse.
Last edited:
Here's your answer: YES
Japan Dave:
I have read your original post. The answer is YES, go ahead and use 4 such units: FiCar IB318. Based on the specs provided by the website, 250 cubic feet is approx 5 times the total Vas of all 4 drivers and that is fine.
You should have flat response down to 22 Hz, and a shallow rolloff below.
You don't need anything below 15hz, so for Home Theatre explosions, dinasaur footsteps and the like, I'd reccomend a sub-sonic filter.
I built an IB sub using 8@ AE IB15's back when they were still available.
Here you see the finished plenum before being placed in the listening room, with a 600+ cubic foot closet behind it.
The IB sub is not new, not the newest latest greatest most exciting design to come down the pike. It's as old as the hills and in a class by itself. It helps to own one's own home
Japan Dave:
I have read your original post. The answer is YES, go ahead and use 4 such units: FiCar IB318. Based on the specs provided by the website, 250 cubic feet is approx 5 times the total Vas of all 4 drivers and that is fine.
You should have flat response down to 22 Hz, and a shallow rolloff below.
You don't need anything below 15hz, so for Home Theatre explosions, dinasaur footsteps and the like, I'd reccomend a sub-sonic filter.
I built an IB sub using 8@ AE IB15's back when they were still available.
Here you see the finished plenum before being placed in the listening room, with a 600+ cubic foot closet behind it.
The IB sub is not new, not the newest latest greatest most exciting design to come down the pike. It's as old as the hills and in a class by itself. It helps to own one's own home
Attachments
Now we are getting somewhere about your purposes, albeit way out of my competence as mega-buck home theater. You are right to visit this forum just like somebody with money in the stock market (even with a financial adviser) needs to read lots about investing and has to start somewhere. For sure, your issues aren't the minutiae of driver parameters so beloved at this forum. You need to have system design addressed first.
Best is to read Floyd Toole's book because it deals with the whole world of reproducing sound in real rooms, not just the short strokes of driver selection just as you would read books on investing.
Returning to your question about bass, and I'm just guessing, I suspect you need an earthquake sub and then a bottom octave of music sub, then good speakers in pairs above. I say this because system design (and final acceptance testing and tuning) becomes immeasurably simpler as you break up the frequency compass and use separate amps. BTW, separating the speaker ranges substantially reduces amp power requirements (which is based on the statistics of sound and goes haywire as the range gets bigger) and restores some sanity to the balance-of-power problem you've run head-first into.
There is no defensible criterion called objectively "flat" and ultimate setting is by feel, guided by microphone snapshots of performance. Start early in setting up a measurement system and your baseline snapshots.
Nice that you have the help of these Erskine people, I guess. But there is no practical way to shape super-low freq room response or to anticipate room boost. So another reason to separate out earthquake sounds* and organ music and bass... so you can wrangle them separately.
I buy my amps at the Salvation Army and feel any dollar spent on gussied-up or high-power amps wasted money that is better spent elsewhere (except for driving electrostatics).
Ben
*Ooops, I mean recorded earthquake sounds if you have the heart in Japan to watch those disaster movies about tsunamis and earthquakes.
Best is to read Floyd Toole's book because it deals with the whole world of reproducing sound in real rooms, not just the short strokes of driver selection just as you would read books on investing.
Returning to your question about bass, and I'm just guessing, I suspect you need an earthquake sub and then a bottom octave of music sub, then good speakers in pairs above. I say this because system design (and final acceptance testing and tuning) becomes immeasurably simpler as you break up the frequency compass and use separate amps. BTW, separating the speaker ranges substantially reduces amp power requirements (which is based on the statistics of sound and goes haywire as the range gets bigger) and restores some sanity to the balance-of-power problem you've run head-first into.
There is no defensible criterion called objectively "flat" and ultimate setting is by feel, guided by microphone snapshots of performance. Start early in setting up a measurement system and your baseline snapshots.
Nice that you have the help of these Erskine people, I guess. But there is no practical way to shape super-low freq room response or to anticipate room boost. So another reason to separate out earthquake sounds* and organ music and bass... so you can wrangle them separately.
I buy my amps at the Salvation Army and feel any dollar spent on gussied-up or high-power amps wasted money that is better spent elsewhere (except for driving electrostatics).
Ben
*Ooops, I mean recorded earthquake sounds if you have the heart in Japan to watch those disaster movies about tsunamis and earthquakes.
Last edited:
Sorry my friend
Hey Dave,
The IB is generally speaking the most fragile alignment when such high power is available as the lack of a restoring force the "box" normally provides is missing. The driver is totally reliant on it's suspension for protection from mechanical dammage. A very large IB array of many drivers could possibly work if wired to limit power.
I think what happened was sort of a rookie mistake. I thought you had four LMS drivers when I "helped" in the bridging... The image of the Sony SACD advert with the rusty sledge hammer and the butterfly comes to mind... I know of another LMS user that crashed 6 at one shot but never really came out on the forum to tell the story. The LMS really needs additional clearance beyond X-max in the motor... 30mm X-max / 48mm X-$$$ as you now know. The thing has 1/2kg mms and a powerful motor 60mm X-mech might not have been sufficient... What's another slice of magnet and a longer pole piece cost on that driver ~$10. But is there 60mm under the bottom spider in the basket??? This would likely lead to another mode of failure the stretched/torn spider. If it's not one thing...
I can say that the end table box I designed long long ago looks like it could help get you into the low teens with some headroom. Looking at the LG web it seems the amp would be capable of 350V p-p bridged 175V per channel, any way you look at it, single driver stereo or bridged into four drivers series parallel the driver is at it's limit. Some feeling out of the system and it's setup/limiters could give you stable results. The amps huge dynamic headroom is uncommon and must be managed with care/respect.
Hey Dave,
The IB is generally speaking the most fragile alignment when such high power is available as the lack of a restoring force the "box" normally provides is missing. The driver is totally reliant on it's suspension for protection from mechanical dammage. A very large IB array of many drivers could possibly work if wired to limit power.
I think what happened was sort of a rookie mistake. I thought you had four LMS drivers when I "helped" in the bridging... The image of the Sony SACD advert with the rusty sledge hammer and the butterfly comes to mind... I know of another LMS user that crashed 6 at one shot but never really came out on the forum to tell the story. The LMS really needs additional clearance beyond X-max in the motor... 30mm X-max / 48mm X-$$$ as you now know. The thing has 1/2kg mms and a powerful motor 60mm X-mech might not have been sufficient... What's another slice of magnet and a longer pole piece cost on that driver ~$10. But is there 60mm under the bottom spider in the basket??? This would likely lead to another mode of failure the stretched/torn spider. If it's not one thing...
I can say that the end table box I designed long long ago looks like it could help get you into the low teens with some headroom. Looking at the LG web it seems the amp would be capable of 350V p-p bridged 175V per channel, any way you look at it, single driver stereo or bridged into four drivers series parallel the driver is at it's limit. Some feeling out of the system and it's setup/limiters could give you stable results. The amps huge dynamic headroom is uncommon and must be managed with care/respect.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.