Underfloor Sub? Will it sound good?

[Rolyasm]

Hey all, I have been talking with a guy about possibly helping me build my home theater. My 18x23 room will have a step up, a rise in the floor for the back row of seating. If he builds a sub under the floor as he is suggesting, anyone have any idea how it might sound? Is it possible to tune it correctly this way? I know sometimes it is important to move subs and speakers around, and I fear having them permanantly placed may reduce my ability to fine tune them. Any suggestions? While on the subjuct, what about it wall speakers? Will they ever sound as good as floor standing or hanging?
Roly

[Andrew Pratt]

If you can't move the sub then use an Eq like the Behringer Feedback Destroyer to make the response more even...actually using a BFD should be something you plan on doing no matter what sub you get unless you are extremely lucky in your subs interaction with your room (none of mine have even been close to good without the BFD inline)

[ThomasW]

If you're going to have a custom built-in sub, you need to test the location first. That can save a lot of headaches later on ....

Most retail in wall speakers are basically a cruel joke as far as sound quality is concerned and they're VERY pricey for what you get.

[Rolyasm]

Well, not reassuring so far. Tony, the guy helping me locally, is using Tannoy drivers for the most part I think, possibly some JBL pro too. The stats he quotes seem good(ie. sensitivity minimum of 97 and so on) and he only uses professional grade products. Not that it necessarily makes a huge difference. So has anyone heard any in-walls that sound as good as non? The drivers he showed me were like 12 or 15 inches, and he said he might place a horn on them. I may just have misunderstood everything he said. He showed me a speaker he made, had a 15" with horn. The thing must have weighed 120 pounds with maybe a 24 inch box. Sorry, lots of babbling.
Main questions: 1) Has anyone heard any in-walls that sound as good as non-inwall? 2)Using the floor as the box, is it possible to build a really awesome sub? He said he would tune it for the room.
Thanks
Roly

Oh Thomas, I still have not ruled out building my own. I sent you my number a long time ago if you ever want to teach me all you know.

[CJ Paul]

A horn or a port? Usually a horn-loaded 15" would require a much bigger box than 24" in ANY direction. It sounds like the guy is planning on building the sub into the riser, which means that it would be behind the front row seating. I dont know, this just sounds less than ideal in so many ways. Also, you mention pro drivers. Usually pro drivers produce a lot of volume (SPL) at a given frequency range, but even larger prosound drivers often dont produce low bass (that last octave and below) because of their (typically) lesser excursion than what a modern "subwoofer" driver would have. I dont know a lot about the current JBL pro-sound drivers, but I dont think they have a lot of excursion. A big driver with low excursion = not as much displacement as you might think.

[ThomasW]

Oh Thomas, I still have not ruled out building my own. I sent you my number a long time ago if you ever want to teach me all you know.

You might want to send it again since I didn't receive it. For a while my MailWasher program was eating all unknown addresses. That problem has been fixed.

Sounds like you're going the right direction. Custom build units with high quality drivers are certainly a very good choice.

For the sub your designer needs to check the proposed placement. This is done by putting an existing sub in the 'sweet-spot' then going to where the sub will be built and listening to the bass quality. If the sound quality is good, then locating the sub there should be fine

[Rolyasm]

A horn or a port? Also, you mention pro drivers. Usually pro drivers produce a lot of volume (SPL) at a given frequency range, but even larger prosound drivers often dont produce low bass (that last octave and below) because of their (typically) lesser excursion than what a modern "subwoofer" driver would have.

A big rectangular thing was coming directly out of black speaker/driver. That is a horn, correct? Does a horn do about the same thing as a tweeter? I specifically asked about depth of bass and he said it would easily reach 20Hz and be very clean. Of course, if I believed everything I heard I wouldn't be on here. I realize this isn't the depth of bass some subs claim, SVS, HSU and even good DIY, so if I do have him build it and tune it to the sweet spot, but it isn't enough, I guess I can always make my own sonotube or buy SVS. Right? Thanks for all the help. You guys are awesome.
Roly

[CJ Paul]

A big rectangular thing was coming directly out of black speaker/driver.

Hmmm, now I'm really confused. A horn sub refers to a horn loaded subwoofer driver. The horn is the box, not the driver itself. I'm not sure what you were shown. It almost sounds like a whizzer cone, except that would be round, not square. Like I said, I'm not sure what he showed you.

[Rolyasm]

Hehe. Okay, let me start over. The speaker had the horn. I have not seen the sub yet. So I was curious about in-wall speakers, which might be using a horn design, and a sub, I have not seen, placed under the floor. No horn on the sub.

[CJ Paul]

OK. Dang, maybe I just didnt read very well. Any way, all the main points stand. You need to work with your builder to test the location within the room before you agree to anything.

[Andrew Pratt]

So has anyone heard any in-walls that sound as good as non?

I have a couple of sets of some in-walls on their way to me to use as surrounds that might be good enough for HT. I should have them in by the weekend so I'll let you know what I think when they arrive. This line has a matching MTM to use for the front three speakers which is a nice option.

As for the sub its a little confusing what exactly you were shown...was the "horn" not just a port? If it was a subwoofer then their shouldn't have been a horn on it at all.

[Rolyasm]

This line has a matching MTM to use for the front three speakers which is a nice option.

As for the sub its a little confusing what exactly you were shown...was the "horn" not just a port? If it was a subwoofer then their shouldn't have been a horn on it at all.

First, what is a matching MTM and what kind of in walls are you installing.
Second. I confused you all. I don't know anything about the sub except it will be in the floor, if I want. I haven't seen it, nor heard it, but he says it should clear 20 hz nicely and sound wonderful. What I did see was the speaker for the in-walls. THAT in-wall speaker had a horn. Big, in wall speaker. BIG. With a thing on the front.
Roly

[cdwitmer]

Apparently a fair amount of money is riding on this project, and it sounds like something that can't be easily undone once it is finished. You may not be an expert on this stuff now, but you will have to live with the results. As long as you are going to this much trouble and expense you might as well take a little extra effort to make sure it is done right. The local expert that has contracted to do this for you probaly has a certain philosophy that guides his approach, and his opinions about what is an ideal situation for your room could be quite a bit different from what people here think. Still, there are plenty of general rules that apply in a general sense -- it is not all subjective and a matter of preference. We are at a disadvantage in that we are sort of like a doctor being asked to do a long-distance diagnosis, and we are being asked to evaluate the diagnosis of another "doctor" (whose competence could be real or only imagined) who has had the advantage of actually being able to see the patient first-hand.

Under these circumstances, it would be great if you could simply tell this expert that since you are still very much a novice in these matters, and yet since it is important to you that the whole thing succeed, you would like to get a second opinion, and you therefore would appreciate it if he would be so kind as to give you a simple written explanation of what he proposes to do. Then, what we need in addition to that is some information on the construction (especially, but not limited to, dimensions) of the room, and what your listening and/or viewing applications will be. If you have particular tastes in your entertainment software (you want maxxed out sound effects in your action/fantasy movies, you only listen to rock, or you listen only to classical, etc.), that information will help too.

Once you can give us that sort of information, we can provide you with some helpful, specific advice.

Oh, while we're at it, it would be good to know what sort of a budget you're on. 'Fess up, we're not your neighbors. (Probably.)

I may have missed something important, but I think I have more or less outlined the only way that we're going to be able to provide meaningful help.

[cdwitmer]

BTW sometimes wall-mounted speakers can sound excellent. A lot are junk -- intended purely for convenience more than anything else -- but when done right, the results can be excellent. Not exactly easy to move around and reposition, however. You only get one chance to do it right.

[Rolyasm]

I should have the quote by tomorrow, so I will send the specs then. Thanks for the input and help.
Roly

[Rolyasm]

Update. More info.

Alright. Finally have the quote in my hand. I am sure I won't be able to tell you all you want to know, but here goes. I will list the products being used and websites to check specs, if possible.

Amplifer: Spectra Sonics 701 power amps. This is an old company located in my home state of Utah. AV guy, Tony, is using 8 amps, biamping fronts, center and sub. 125w per channel. Rear channels will be run off receiver. Spectra Sonics Specs: Draw of 1.5 amps @8 ohms, 6.0 amps @2 Ohms. Professional rated, not "A" rated. 122 db between 20-20Khz. Peak resistive. Damping Factor (output imped. amp/imput speaker) of 1000+. I have something written down about 1000RMS, but uncertain what he was telling me.

Receiver: Sherwood R945 A/V receiver. I might change this to a newer model, or one with a better remote. Thinking of teh R965 or the Denon 3805, both around $1,000. Since this is an older receiver, specs are hard to find, but it is a 100x5 DTS.

Speakers: Tannoy CMS12 TDC-8. These speakers will be mounted for 6.1 or maybe 7.1 sound. They will be in wall. AV guy will tune them to room. These speakers are also hard to find specs. Here is a site. http://avalive.com/products/pdetail.php?pid=66434
These speakers are rated for 24 hours of Pink Noise. I think hi-fi is 5 or 10 minutes.

Subwoofer: JBL Pro 15" : Forgot to get the exact model, but here are the facts I have. High power, low frequency, 600w AES(application engineered series)Vented Gap Cooling, 8 Ohms. He will build it into my rear riser and port/tune it for room. You can read about the AES series in this PDF :http://www.jblpro.com/JBL_Profession...atalog2005.pdf Page11
or http://www.usspeaker.com/JBL%202226h-1.htm. The specs say it is only rated down to 30 Hz, so I am a little worried it won't give me that deep, true base as say DIY, SVS, HSU, etc. Will I have to have a seperate in the corner?

My room is 18x23 with 9 foot ceilings, though I can change this since I am building. Might slope the ceiling to avoid those 90 degree angles. I am going to offset the studs to help contain sound. Probably use foam or carptet/fabric type stuff on walls.

I will get more info. Does this help at all. My budget is around 10k, with video, might go over. Thanks.
Roly

[Dennis H]

Sounds good except for that JBL. It's an outstanding pro driver and I love 'em but it isn't really intended for sub use. It's meant to be a midbass driver in PA applications. Fs is 40 Hz and Xmax (excursion) is 8 mm. For the same money, you could get an Avalanche 15 as discussed on this forum, possibly the best 15" sub driver you can buy at a reasonable price. Fs is 16 Hz, Xmax is 27 mm and it uses the XBL^2 motor technology for extremely low distortion.

http://www.ascendantaudio.com/Avalanche%2015.htm

[Rolyasm]

Dennis. Would the Avalanche hold up as well and as long as the JBL pro, which I think is used in auditoriums, etc? I can see the stats look better. I can't believe the JBL only has a xmax of 8, but that is what it says in the specs. My AV guy swears it will be too much bass. Hmm. Maybe I should challenge him a bit. Also, if he insists it will be good, and something he is comfortable and familiar with (ie, won't budge), could I build my own sub to make up the difference?
Roly

[cjd]

I would inquire what his path will be when you destroy the woofer or find it is not adequate. Get a guarantee of satisfaction. See what kind of results have previously been achieved with this driver by this individual.

If you're talking sub-woofer, it should be comfortably flat to 10 or 15Hz in-room. And capable of output at that frequency to reference level (125dB? I don't remember). The LFE on an increasing number of films make use of tones this low. And a full pipe-organ hits 16Hz on its biggest pipe, so we're not just talking funky movie track stuff. I would count the cannon in the 1812 Overture to be *slightly* abnormal.

Most people don't really comprehend true sub-bass. A huge bump in response at 40 or 50Hz and they think the thing slams like nothing else and has awesome bass response, even if it has zero output at even 30Hz.

It sounds like you are not one of these people. I would make sure the builder understands your expectations. Get specifics, not vague guarantees like "it'll have tons of low bass output". What's "low bass"? And what's "tons"?

C

[Dennis H]

I've owned an older version of those JBLs and they are very good drivers for their intended purpose, 40 Hz up to the mid 100's. I have no doubt that the Avalanche (and a number of other dedicated sub drivers) would mop the floor with the JBL in the 15-80 Hz subwoofer range. That said, if your SPL requirements are modest, the JBL should work just fine. I guess you could always add another sub if one doesn't do it.

Dealing with your installer, well, that's between you and him. I doubt many of us here would choose any of the components he has picked as a first choice. He seems to be from the "high efficiency" school and that's a love 'em, hate 'em kind of deal. But what counts is making the whole thing work as a system where the whole is more that the sum of the parts and, if he can do that, good enough. Have you listened to other systems he has built and did you like the sound? That's what really matters.

[ThomasW]

Prior to building my big IB, I was running 4 Audax Prosound 15"s in a room 18'X13'X8'. (The Audax Prosound drivers were easily the equal of anything made by JBL.)

When DVDs came out I was bottoming them ALL the time.

The JBL driver he's referring you to isn't up to the task of functioning as a high output, LOW frequency subwoofer. It will play VERY loud, but it won't play low, and low is where it's at for HT.

You need and want something that has output down to 15Hz-18Hz, to get the full impact of DVD soundtracks.

Go with a pair of Avalanche 15" or 18", make him tune the system to 16Hz using HUGE diameter ports. 10" diameter is about right.

[Rolyasm]

Boy, this is good stuff. I am so excited. CJD, I will definitely ask him about guarantee. He has one set up in his home that I will listen to soon, and he is just finishing another in about 2 months that the owner said I could listen to. I will be critical. You are right, I am one of those people who want bone-crushing base. I want my head to implode when the Balrog strikes the wall. It seems obvious that this bass won't do the job. Dennis: How would I know what the SPL measurements will/should be? My room won't be framed for another few months. So how do I address this? He is definitely High Efficiency. Everything is "high" this and "clean" that. Have you heard systems like this? Does it work well?
Thomas: I will speak with him about the Avalanche. I know he will say something like it isn't comparable, or is Hi-fi, not pro, equipment, and probably argue his driver. Any suggestions how to convince him? What stats can I show him. He tells me Hi-fi speakers are only rated for 5 mins on pink noise, while pro is 24 hours. Does this sound true? I will print out some Avalanche stats and take him, but could you direct me to what is important. I don't see any sensitivity on the Avalanche?(I am sure he will want to know). My AV guy said he was going to set the crossovers around 60Hz. Will the Avalanche pick up from this crossover alright? Last, he was going to make some huge chamber under the rise for the sub. Will this Avalanche work for this, or is it for smaller enclosures? Also, Thomas, I am still very interested in building my own sub. So if he does the underfloor (riser) sub with the Avalanche, is there any reason to build another? Maybe just cause it would be cool? Thanks All.
Roly

[Dennis H]

I am one of those people who want bone-crushing base.

Well, I think you've answered your own question there.

[cjd]

HUGE chamber? And he's going to waste it on a ported alignment with a driver that'll bottom if you look at wrong in this alignment?! Not that porting is bad - as Thomas said, a pair of A18's, 10" port tuned to 16Hz is about right. Two of those will probably take a few thousand watts transient without a second thought. Which should be around 130dB IIRC. If you're playing these drivers anywhere near the point at which they will self destruct, you're doing some of that "bass drag-racing" stuff and *expect* to destroy the drivers after one burp. You *can* bottom the Avalanche's because if they didn't bottom, they would just, well... come apart with no warning if you push 'em too far. This out of Chad's mouth - I got the impression he'd *done* this. Which means clean output far beyond where they're being used sensibly.

An pair of Avalanche 18 drivers could make your jaw put a hole through to the other side of this ball of dirt on which we live (room size dependant in part, and this really assumes HUGE chamber, sealed, with some EQ to handle room issues). With 500W. And that would be with power handling to spare in a big big way.

I run a pair of lesser (about the bottom of the pile that are still IB capable) 15" drivers on 200W and could probably destroy them in a heartbeat.

Pick up "The Fantasy Adventure Album" (Erich Kunzel, Cincinnati Pops Orchestra) and play one of the T-rex tracks. If you don't get the heebee jeebies around 13 seconds in, the system isn't producing adequate low bass. 10Hz bass to be specific. You will not hear it. Second footstep you can hear just a tad. Third is accompanied by crashing underbrush - if that's the first you hear, the system is inadequate for low bass. The hair on the back of my neck rises and I get shivers down my spine in my room - about 1200 cubic feet on that pair of 15's. 3000 cubic feet of sealed "enclosure" behind the woofers.

High eff is fine, and certainly has its place. Low bass is a totally different game - one of displacement.

If you want to have fun, you might suggest that for a subwoofer, 40-50Hz makes more sense as a cross point since those bottom few octaves can be hell on a driver, and 60Hz is already starting to be too directional...

[Rolyasm]

[QUOTE=cjd] With 500W. And that would be with power handling to spare in a big big way.[QUOTE]

So my very solid 125w/channel, 2 channels for sub driver, won't be enough to power the Avalanche?(250w total). The amp blocks he is using are costing me $85.00 per channel. Could I just use more of these to drive the subs, or would it be better to get a dedicated amplifier? 8O

[CJ Paul]

Its starting to sound like your installer is more interested in convincing his customers to use the gear he wants to use than actually allowing any input into the system design. I would proceed with extreme skepticism and stand your ground. I would recomend a decent pro amp from Crown or something with closer to 500w per channel if you are going to go with the big Avalanche drivers. I think the Avalance drivers are designed to either be run off one voice coil or with the voice coils paired either in parallel or series. I dont think you can run each voice coil off a seperate amp channel. So yes, with the equipment you are talking about, you'd be limited to 250 watts. As an aside, with conventional dual voice coil woofers, you ca run the coils off of seperate ampes so you could in theory use 4 amp channels, but that's not going to work here and you might as well go with a higher powered amp.

Any way, there are others here that can help you more with those specifics, I would just reitterate that this is YOUR money. You should be telling him what YOU want, not the other way around.

[ThomasW]

I know he will say something like it isn't comparable, or is Hi-fi, not pro, equipment, and probably argue his driver.

It may not be compatible with his myopic view of the audio world
(or what he likes to sell, think profit $$$$), but that doesn't mean that they aren't exceptional drivers. And with a proper amp they'll work fine with your other speakers.

BTW there's nothing inherently wrong with 'Hi-Fi' drivers. As with anything else, there are high quality and low quality Hi-Fi drivers.

Any suggestions how to convince him?

You don't have to convince or prove anything to him. It's your money, it's your theater, not his. He works for you.

What stats can I show him. He tells me Hi-fi speakers are only rated for 5 mins on pink noise, while pro is 24 hours. Does this sound true?

Who cares? How much pink noise are you going to be playing? You're building a home theater, not a real theater. There are significant differences between the two

Some of his 'tests' are nonsense. The Avalanche drivers can play THX reference levels 24/7 and not break a sweat.

Ask him to quote 'Hoffman's Iron law'. Then let us know what he says.

Pro sound gear isn't intended to play low bass. It's just too damned expensive to do in a concert venue. BUT your HT isn't a concert venue, so you can have, and should have low bass. There's a lot of stuff recorded below 25Hz on DVD soundtracks, you deserve to hear that information.

So my very solid 125w/channel, 2 channels for sub driver, won't be enough to power the Avalanche?(250w total).

No, it will take a bigger (more powerful amp) to drive those woofers. Note that doesn't mean that there's a problem with the design of the drivers. In order to play LOW notes, the drivers doing that are inherently inefficient. That's a part of Hoffman's Iron Law.

Now if he thinks that low efficiency drivers are inherently 'bad', then you have a problem. You're dealing with a person who's mindset is stuck in the 1950's.

[Rolyasm]

I understand. So for a room my size, should I go with 1 or 2 drivers, and 15" or 18"? I will ask about the Hoffman's Iron Law, just for fun. Did I mention this is a friend of the family and I have known him for 20 years? I guess that is what makes it more difficult. He says he is getting me good deals on all the equipment, and I think he is excited about doing the project. He is very opinionated. I kind of feel like he is doing a favor for me at times, be yes, it is my money and I am paying him. Thanks again. I am gone for the week, check back while on the road or next week.
:T
P.S. At times, I am still thinking of going conventional, (ie Earthquake Amps, online speakers like axiom or pinnacle). Hard decision because I can't actually hear any finished HT with similar stuff. I am a nerd.

[ThomasW]

Go with 2-15"s. A custom designed and built sub should sound MUCH better than any retail design.

He says he is getting me good deals on all the equipment

Well let's see the invoices.

I did a google search for Spectra Sonics amplifiers and found nothing.

The Tannoy speakers will sound quite different from from anything you're used to hearing. Probably be a good idea to go someplace and listen to a set of high efficiency speakers just for comparsion

[Bent]

I think the deal with a lot of custom installer is that once they estblish a design on wheich they have managed toi satisfy most of their customers, they just close their mind to the prospect that anything else will work as good (or likely better by a huge margin).
A custom installer isn't going to want to design a new enclosure and then test and tweak it to perfection - time is money for them. I have no idea how competitive the custom install industry is, but I will say that human nature will always prevail and thus the easy way out will most always get chosen.
Try to work with the installer with this in the back of your mind and maybe they'll approach it with an open mind too.

[Rolyasm]

I did a google search for Spectra Sonics amplifiers and found nothing.

I did the same. The only stuff I found was from the 1950's. I will try to find out more info on them. He says I can still get replacement parts for all the stuff, but I better check. I wish he wasn't a friend, but wish in one hand and sh*% in the other and see which fills up quicker. Bent: I think you are right. He feels comfortable with his subs/drivers. I will ask him anyway, see if he squirms. Maybe he'll just go, "ya, no prob." But I will ask. I'm out of town this week, but the hotel has internet. Booya. I'll see him next week.
Thanks for info.
Roly

[ThomasW]

He says I can still get replacement parts for all the stuff,

I guess that's not really the point. Anyone cay buy raw components if they know what to buy.

Not to be morbid, but if he has a car accident or heart attack, you're stuck with amps no one has ever heard of, let alone has parts for.

If you want really want to use prosound amps, go with one of the big names QSC, Crown, etc. You know they'll be around to service the equipment.

As for desigining a sub it's basically childs play. Jon and I are both in our 50's. We've been designing speakers since we were teenagers. We'll be glad to help with the sub.

Since the raiser will be the enclosure, make sure it's built air-tight.

[Dennis H]

Are those tube amps?

I ask because of their vintage and the fact that many of the high-efficiency crowd have a preference for them. They sorta go together. Tube amps don't have much power so they need efficient speakers. Efficient speakers can sound rough if fed a flat signal so they they often sound better with the coloration of a tube amp.

If so, consider that tube amps are going to need ongoing maintenance as long as you own them. Been there, done that, moved on, and that was before tubes got expensive and hard to find.

Dennis (as old as Jon and Thomas, built my first tube amp from a kit when I was 17)

PS - replacing tubes used to be easy. Every few months, you'd pull all your tubes and take 'em down to the local Safeway or other supermarket. They'd have a big self-service tube tester with a rack of tubes below it. You'd plug them in and the meter would tell you if they were still good or not. Then you'd search through the rack to find replacements for the bad ones at a buck or two apiece. Now you have to decide for yourself if they are bad and pay big bucks for a Russian replacement since nobody makes them anymore in this country. Ah, progress....

[taz13]

Building a recording studio are we?

[jdybnis]

With that kind of budget for audio, and the luxury of building a dedicated room you can have a mind-blowing HT.

my 2 cents:

Hire Rives Audio or another acoustical design firm to architect your room. It is relatively cheap and acoustics will have a dominant effect on sound quality if you just try to wing it. Good acoustics can save you money on equipment. You won't be able to change your walls post construction. Room treatments are expensive/ugly. Even state of the art DSP room correction ($$$) can't do much in the mid to high frequency range. Rives will work with your installer and/or architect and/or builder. A sloped ceiling is probably a good idea but can any of them tell you what the best angle is and why? An acoustic engineer can.

Don't tell your custom install guy how to do his job. If you push him into using the Avalanche drivers and the bass doesn't turn out right it's your fault. You can't expect him to learn to work without his normal tools just for your job. Especially if he's already cutting you a deal on price.

Do tell him what you want from your system and how much you want to spend to get it. Be adamant that he commits to delivering on those goals. Put your requirements in writing! Equipment lists and specifications are great. But what do you do if it all comes together and you don't like the result? If your goals are not in writing you're going to get what he thinks is best for you, which isn't necessarily what you think you're asking for. Verbal communication isn't enough here.

If he balks at your requirements (e.g. bass flat to 10Hz), listen to what he says and assess if that is really what you want. If he can't adapt to your goals then he is the wrong person for the job. There is no way around it. But if he is willing to adapt, and he is committed to your goals then he will find a way to deliver what you want with the tools at his disposal.

[Rolyasm]

Thomas: I just talked to my uncle who works with Tony, the AV guy, at least they work in the same building. My uncle says he has been to the Specta Sonics building and gave me their number. I tried to call, nobody answered, so I left a message. I agree, I need more facts.
Dennis:No, not tube amps, in fact, they look like, and may be, the same things Taz is showing in his pics.
Taz: Whoa. I swear those are the same amps that AV Guy is showing me! Same thing. They look sissy, don't they? Is it possible they could really work as good as AV Guy says? I expanded the picture and see they are Spectra Sonics. Not the exact thing. I think the ones AV Guy has shown me have more circuitry perhaps, and I don't remember seeing a fuse on anything, though I could be wrong. Where did you get the pics and do you know anything about S. Sonics?
jdybnis:Do you work for an acoustacal design? I have thought about hiring someone, and have mostly done room design off the internet. So far the golden rule of room size, offset studs, sloped ceiling and wall treatments are what I had planned for and don't have thousands to pay someone to design a better room. If I found someone at a reasonable price I would seriously think about it. Know anyone in Utah? I think your's is the first opinion in defense of my AV Guy.
You said "Don't tell your custom install guy how to do his job. If you push him into using the Avalanche drivers and the bass doesn't turn out right it's your fault. You can't expect him to learn to work without his normal tools just for your job." Shouldn't he be able to change things if he knows what he is doing? It sounds like subs are fairly easy to do, so a guy with his knowledge should be able to change, I hope. I see your point though. I should really lay down my goals, but since I have never heard or had bone crushing bass to 15 hz, I don't know if that is really what I want. I do know I want incredible bass, precise and powerful, and can that be achieved at 30 Hz? I am just to inexperienced to know what I need to acheive what I want. I guess that is why I am on here trying to educate myself by listening to smarter people, who I greatly appreciate for their time. Thanks again everyone.
Roly

[ThomasW]

The amp situation is a bit weird. That means there's a chassis and the amps are plug-in cards (modules). Nice neat and tidy. But how come no one on the planet knows about this company? Primary down side to this design is of course that they share a main power supply. If that power supply dies you lose all your amps. Since it's an industrial unit, the reliability should be pretty good. The 85 watt modules however aren't nearly powerful enough for any sub, let alone a high excursion one.

You should be able to tell tell the guy what you want. If he's really your 'friend', he'll understand.

He may give you some grief about using high excursion (low efficiency) drivers for the subwoofer. BUT that's the only way to get low frequencies, unless you want to live with a folded horn 30' long.

In this day and age watts are cheap. So using low efficiency drivers don't present the problems it did years ago.

Believe me, you want lots of bass output below 40Hz. And yes it's possible and not very difficult to 'match' a low efficiency sub, with high efficiency mains and effects speakers.

[taz13]

Actually Thomas they are used in a fair number of recording studios and are quite flexible. The modules come in different sizes and ratings. The main power supply is quite good and as an electron chaser I can tell you they are a lot easier to repair when you can easily pull them out and work on them.

As to where the pics came from, I can't remember but I have installed SS units in recording studios in the late 70s and early 80s. I may even have schematics for some kicking around. Also explains the requirement for high effiency speakers.

I was at the time a tech who worked mostly on musicians equipment (Fender, Marshall and Garnet were my specialties) as well as doing sound work both live and in studio when not maintaining RATCON equipment. The music part was part time the rest of the time I wore green.

Man Dennis that PS brings back alot of memories. I learnt real early to make sure that the tube locations were marked with the actual tubes being used. That was what got me into the trade in the first place.

[Rolyasm]

Just called AV Guy. He said Specta Sonics, SS, is still used all over the world, but mostly by high end places like radio studios, etc. and that most people never deal with this type of equipment. I pressed him on the sub and he will do whatever I like, he even has bigger drivers that go lower. However, he did tell me that he doesn't like the way deep bass sounds, so maybe his preference a key factor here. Also, he said most drivers that claim low bass like 16 Hz are just distortion machines, using high power to create noise. He tried to explain something about as your driver reaches resonance the impedance increases so it becomes very hard to cleanly and accurately drive that low of Hz. He also described room size as being a factor. Something about 4x the room length is wavelength created, so you need a large enough room to even accurately produce this frequency wavelength. I wish I could record our conversations or write faster, because he always loses me and everything I just said is probably the opposite of what he really said. So he will take a look at Avalanche, but thinks if he uses his 18" we will be fine. He says if that is what I want, he will do it. I have looked at Avalache and see no efficiency rating. Anyone know what the rating is? He also suggested making a resonator( I think) something that just gives you the sensations below 20hz. Maybe it is like a radiator? At least I think he is willing to work with me. I will find out more on the sub and resonator thing. Can someone find out sensitivity on Avalanche, and power rating?
Taz: Did you like the sound of SS. Any problems? Are they really as efficient as AV Guy says?
Thanks.
Roly... one step closer. One small step for mankind...

Edit: just found this SS piece on Ebay. Not sure what it is.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=23793&item=3778486955&rd=1&ssPageName=WDVW

and this :http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW

[ThomasW]

He tried to explain something about as your driver reaches resonance the impedance increases so it becomes very hard to cleanly and accurately drive that low of Hz. He

We're talking about using drivers that have a Fs (resonant frequency) of 16Hz. And no they aren't distortion machines.

so you need a large enough room to even accurately produce this frequency wavelength

Obviously there's a problem with that statement since headphones can produce 20Hz notes.

He also suggested making a resonator

He's probably talking about a bass shaker (tactile transducer). They're fun for visceral effects (amusement park rides). However we're talking about reproducing music.

As music progresses there's more and more subsonic info being recorded. Pedal bass synths are one example. Obviously pipe organs go REALLY low (14Hz) and they certainly aren't just distortion.

Here's something to ponder. This is a plot of the low "E" string on an electric bass guitar (tuning 42Hz) . Notice anything interesting?



No I don't know the rated efficiency of the Avalanche drivers. An email to Chad will get you that data.

[Dennis H]

The usual "rated efficiency" isn't really relevant for subs because it's measured at much higher frequencies than you'd expect the sub to play - typically an average between 100 and 1000 Hz. What counts is the power requirement at the lowest frequency you'd want to play and the "high efficiency" drivers lose it there because their LF rolloff starts so high. They are very efficient at several hundred Hz but very bad at 20 Hz.

I happen to have both the JBL 15 and the Avalanche 18 plugged into one of Siegfried Linkwitz's spreadsheets, that lets you look at power levels at different frequencies. To drive the JBL to Xmax at 16 Hz, with the speaker in free air, not in a box, you'd need an amp with an 8-ohm power rating of 27.1 watts. To get the same SPL out of an Avalanche 18 in free air, your amp would need an 8-ohm rating of 7.6 watts. So, the sensitivity of the Avalanche 18 down low is 5-6 dB better than the JBL 15. At higher frequencies, the tables would turn and the JBL would be much more sensitive. Of course, when you put them in a box, the power requirements for both drivers go up dramatically, but the trend would still hold.

[Rolyasm]

THomas:I looked at the graph. You'll have to tell me what to look for. the circled area is around 55Hz and the dB all above 30. Not sure what you want me to see. I know what bass shakers are, this isn't the same. This is something else, I will find out. My problem is I am too dumb with lingo to catch all of what is being said. I will show him the Avalanches though, see what he thinks. I must be wrong about what he was saying about frequency wavelengths. Is there anything else he could have been talking about that would be limited by a small room?
Dennis: AV Guy did mention power requirement. Is that the same as Pnom? I will show AV Guy the specs on the website.
At what frequency would the JBL catch up to the Avalanche?
Everyone:So you have all heard sub 20hz subs that sound clear and accurate? Do they get "Slow" in response that low?
Roly

[Dennis H]

Is that the same as Pnom?

No, nominal power (Pnom) is another one of those irrelevant specs. It's the power the driver can handle without melting the voice coil and it will never be a concern in a home setup. The drivers will go CLANK from overexcursion long before you melt one.

The sensitivity I was talking about is about the same as efficiency. Down low, the Avalanche is more efficient (requires less power for a given SPL) than the JBL. Technically sensitivity and efficiency aren't the same thing but close enough for guv'mint work. Sorry, I already closed the spreadsheets but, at normal sub frequencies, the Avalanche is more efficient than the JBL.

[cjd]

Everyone:So you have all heard sub 20hz subs that sound clear and accurate? Do they get "Slow" in response that low?
Roly

I have one as do many many others. Below 20Hz, and cleaner and more accurate is pretty much not reasonably possible. It's an IB. Two 15" drivers. 200W. 1200 cubic feet in-room, 3000cubic feet behind the drivers. Check out the Cult of the Infinitely Baffled if you're curious. ThomasW is the resident Guru and knows what the heck he's talking about here in a pretty big way.

Slow it is not. The smaller your box, the "slower" it gets in fact. Port (or add a passive radiator) and it gets "slower". Slow is a vague term though.

C

[Rolyasm]

Below 20Hz, and cleaner and more accurate is pretty much not reasonably possible. It's an IB.
C

What is IB? So are you saying that it is not reasonably possible to get clean and accurate sound below 20 Hz because we can only hear to 20? If so, is it possible to get clean and accurate down to 20hz?