Decent Bass and Happy Neighbors

Discussion in 'Subwoofers' started by GaryL1, Aug 9, 2013.

  1. GaryL1

    GaryL1
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    Hi All,

    I've recently moved house and want to improve my sound system. The room is 18' wide, and 13'5" deep and 8' high, with a wooden floor, with a cavity underneath into the foundations, think it's about 2' deep, but I haven't had floor up yet. The house is detached. There is no room for sub woofers on the front wall (due to doors, screen and front speakers), but there is plenty of room on the back wall. The back wall is an exterior wall, plastered breeze block on the inside then cavity thermal insulation, then red brick on the outside, and is approx 11" thick. Behind this wall is about 5' then the neighbors wall (same construction as mine) which runs parallel to mine for 2', then cuts away and runs parallel to mine at about 11' away for the rest of the room.

    Now ideally what I want is to play movies at -10dB from reference (Dolby D and DTS), going right down to around 12-14Hz (or as close as I can get). I also wanted two subs (currently with a single sub, as I can't sit still and by moving about, due to the (close) distance I'm sat from sub, the pressure varies by a noticeable amount and then I'm aware where the sound is coming from and the whole experience of being there is broken). So I was thinking two SVS PC13-Ultra.

    Now would those subs completely overpower the room and become unmanageable? Would a SVS PC13-Ultra and a SVS PC12-NSD work well together, to produce something a little bit more manageable, or is mixing the subs like this just asking for problems?

    I'm happy I can take anything above 100Hz right down to under 30dB(A) in my neighbors house without issue, and I'm not planning on having it as high as -10dB very late at night, so I'm happy that this part is acceptable. I'm thinking of getting 2 front speakers that can go down to 32-38Hz @-3dB and have the cross over at 40Hz to 50Hz, which will be 11' away from the back wall, and the subs placed either in the back two corners or 1' to 2' from the back wall (depending on room nodes etc). This means there is a maximum of 111dB(C) coming through the sub woofers (115dB LFE + base from other channels -10dB from ref) at 5'. Now for the bottom two octaves (10-40Hz), I'm not convinced the walls are going to do much in the way of knocking out the bass getting to next door, to a level of 30dB(A), which I'd imagine is a reasonable level (for waking hours). So firstly given I've got a theoretical maximum of 111dB(C) (at 5') (roughly 79dB(A) @40Hz, 67dB(A) @20Hz) through the subs, what is the chance of this being all in the 10-40Hz range and for a long time (say 4seconds per 5 minutes, or 3 seconds continually)? Is there anything I can realistically do to limit what the neighbors hear/feel without destroying the quality in the room, such as placing bass reflectors; bass traps in the room/under the floor; placing the subs right next to the sofa; turning them down by as much as 20dB; put 2' of glass fibre backed with gypsum board and 4' high along the outside of the wall (and risk looking mental); or build by own closed passive subs in the sub-floor?

    Any help or advice would be much appreciated.
     
  2. KelvinS1965

    KelvinS1965
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    I'm a similar distance to my neighbours house, but since my floor is a concrete base it will act quite differently to your new place. At the moment I only have a BK Monolith, but having tested the sound transmission by putting it on near reference level then going outside, where I can only feel the bass through my front porch supports but I can't hear it. Having tested this I'm happy to play films and concerts at only a little below reference (for my own hearing's sake :D ) even after midnight.

    I'd suggest you try a similar test maybe not at midnight, but at least when it is quieter outside so you can see how much sound gets transmitted outside. Bare in mind that it then has to get through their walls (or open windows in the summer I suppose) as well, though general road noise, etc seems to mask anything from mine. I do have the M4 about 3/4 mile away so there is the distant noise of traffic which helps in this case.

    FWIW my room is a little longer at 22' but similar width and height. I'm planning on upgrading my subwoofer(s) during this autumn/winter to a twin 12" DIY at the rear of the room and a single 15" DIY near the front, so I'll let you know how I get on if you're still pondering. I would hope that these 3 subs will exceed a PC13-Ultra since the figures suggest I should be able to hit reference at 20Hz and well over 100dB at 10Hz.
     
    Last edited: Aug 10, 2013
  3. kbfern

    kbfern
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    Regarding the subs themselves do you already have one or two or are they yet to be purchased,as I think a pair of USC15 subs powered by a single 6000w amp will offer a better solution and at a lower cost.

    A pair of PC13 ultra's will be £3200 approx a pair of USC15's around £2500 in a basic black vinyl finish.They have a full dsp eq built in and offer super value and offer exceptional performance and go very low in addition to higher end slam that the SVS's don't seem to offer (I am a previous SVS PC+ owner).
     
  4. mojogoes

    mojogoes
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    I had my neighbour 2 doors away with both mine and there front windows open thinking it was thundering and lightning raining down on them when I had wotw playing yesterday :rotfl:...............Oops:facepalm:
     
    Last edited: Aug 10, 2013
  5. GaryL1

    GaryL1
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    In the next few weeks I'm getting the house rewired, double glazing replaced and some minor building work, as such most of my stuff (including sub) is in storage. So my plan was while the floor was up, to lay the rear speaker leads (I'm going for 5.1 not 7.1) and subwoofer cables in place, but if I don't know where the subs are roughly sitting, or if they are passive or active, this could be somewhat tricky to do, guess I can lay conduit down for the subs and limit the amount floor boards I need up once I know what I'm doing.

    My sub is a Sony SA-WX90, think it's got a similar range to the BK Monolith (but not the quality), which compared to something that can nicely hit below 20Hz, I wasn't sure how accurate a test using the Sony would be. I think the neighbours are nice enough to let me come around and listen, I just didn't want to buy two nice subs, and then find out that I can't use them and have to send them back after experiencing them.

    As for external noise, I live on the edge of a Coventry with a road about 20m in front of the house, and the lounge/HT to the rear, it's or at least is meant to be a 30mph road and on average 1-8 vehicles pass a minute during the day/evening, which inside my house is hitting up to, I would say 60dB, with the front windows open while in the front rooms, rear of the property with the windows open 40dB, add double glazing, it not really going to be busy or fast enough to act as a suitable mask. Depending what the cavity under the floor is like I could look at building up two brick columns that then support the floorboards directly under the subs, in an attempt to dampen the response of the floor.

    I like the idea of building my own sub, but I don't think I can get anywhere near the result of a pre made sub, without paying a lot of money on instruments to measure it's frequency response, to enable fine tuning, of the enclosure and the signal.

    The SVS's are yet to be purchased, the reason I picked on them is due to their deep response, good reviews and stylish good looks, this isn't a firm decision more of a ball park. I was looking at a crossover of 50Hz or lower from the front channels, so ignored the top end of the bass, but the LFE goes all the way up to 120Hz. So the 13" SVS's (on their own at least) are probably not the best pick. Do you know where I can find more information on Gecko's USC subs, or is it a case of heading down to Newbury for the day? As the total system I'm looking at is going to cost around £15k (over a few years), including projector and amps, a £700 saving and fuller sound is definitely worth looking into, thanks :)
     
  6. GaryL1

    GaryL1
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    Yeah, that's the kind of thing I'm trying to avoid... not sure what's worse the neighbours thinking what they hear is real or them hearing just enough of the system for it to become annoying over the length of a 3 hour film. To be fair it's not the worst 'trick' that has been played with WOTW. With windows open for me it's always going to be quite time
     
  7. kbfern

    kbfern
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  8. mojogoes

    mojogoes
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    Yeah but then again I can always close my window problem solved and I guess they could do the same:laugh:
     
  9. GaryL1

    GaryL1
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    Thank you very much, I might take you up on the offer in a few months time, once I've got settled and had chance to test what leakage I get from my old Sony.

    I wonder, is it possible to have a custom sub built to turn void beneath my suspended floor into a subwoofer, and still be able to get enough gain on the higher frequencies to come through the carpet, or would it only be good for the deepest frequencies and need some form of crossover with smaller subs above carpet level.
     
  10. kbfern

    kbfern
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    GeckoDan would be the best to advise on any custom subs he is the designer/engineer of the USC subs, They do custom jobs so if it can be done they will be able to design build and even install if required.

    I would think as sub in the void with some sort of grill cut out of the carpet would work ok.

    If you want t o come over anytime just let me know and we can sort something out no problem.
     
  11. Nimby

    Nimby
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    If you have 2' clearance between the floor and subsoil then an infinite baffle subwoofer would fit.
    You'd need a couple of 18" Fi IB318s in an opposed driver box under the floor and a Behringer pro amp.
    All you'd see would be a floor grill. No boxes in the room and "cheap as chips at about £1500" :D

    The downside is ensuring your room has a reasonable response from your intended IB site using your present subwoofer as a test box.
    Moving an IB after installation is a real nuisance so you want to get it right first time.
    An IB requires a heavy investment in time and knowledge gathering to get right.

    On the other hand, you have (potentially) much more flexibility and a better chance of optimising your room's response, using the commercial subwoofers already mentioned.

    You may also get more chest thumping drive and impact from sealed boxes. While IBs are best known for their very deep bass.
     
  12. KelvinS1965

    KelvinS1965
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    I have to agree with Nimby regarding testing first: I was all set to build a 4 x 12" driver in ceiling sub (NOT an IB sub, but just using the void space to fit a cabinet in) at the front of my room. However, I modelled it using REW (the latest version has added a modelling section) and the response would have still had the large 35Hz (30-50 in fact) suck out due to a null caused by my MPL distance from the sub. Since the MPL is otherwise ideal for the main speakers, viewing distance to screen and room aesthetics I had to give up the in ceiling idea. :(

    I've since found that I need a mix of subs front and rear to get something close to an even response (and I'll bet it'll still take some major setting up). I'll still have a couple of peaks, but EQ should be able to pull them down.

    If I'd built the in ceiling sub without checking this out I'd have been seriously disappointed as it was going to cost about £1,800 in parts alone.
     
  13. mojogoes

    mojogoes
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    Hi Kelvin I bet your now happy you didn't go with the ceiling sub idea.........have you already got the 8033 if so I can't see you having an eq messing about for ages problem.
     
  14. KelvinS1965

    KelvinS1965
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    Yes I'm glad I didn't go that route, though I'd have really loved having an 'invisible' sub. :cool:

    I still think there will be a certain amount of fiddling about having two separate subs at opposite ends of the room: Things like phase, individual levels to best smooth the response maybe, also not sure how to deal with the delay since one will be 4 metres away and the other nearer 2 meters.

    It's all largely academic at the moment having been busy with DIY, the garden and on holiday I haven't even switched my main system on for about a month. :eek: At least the little bit of TV I've watched on my new 39" Panasonic I bought for my conservatory set up. :)
     
  15. mojogoes

    mojogoes
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    Just set each sub at 70db or a little higher if need be at the mlp and the rest will be sorted automatically..........yes one sub maybe working a little harder than the other as your using subs that are not exactly the same but because you'll spec each sub with ample headroom this shouldn't be a problem.
     
  16. GaryL1

    GaryL1
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    Thanks All,

    Definitely will try with existing sub before I start modifying the floor. Can just imagine the look on the joiners face when I'm explaining why I've cut three massive wholes out of the floor and that's why the whole floor needs replacing, and yes I would be making another hole as soon as his finished, in search for that allusive sweet spot.

    So if I'm using Audyssey on an AVR with 2 sub outputs, will all this sort itself out, can you also mix and match subs in this way? E.g. use one that is good for 25Hz-120Hz and a second that is good for 15Hz-80Hz, without Audyssey pushing each sub too hard for the frequency that they not so good at, or would manual intervention on the amps be needed to dial this unwanted gain back?
     
  17. kbfern

    kbfern
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    To use 2 different subs with Audyssey you would need an amp that has two fully separated sub outputs and XT32/pro the 818 for instance has 2 outputs but they are both linked so can only effectively see 1 sub and equalise for that.

    Higher end models have 2 fully independent outputs so you can do as you suggest.
     
  18. mojogoes

    mojogoes
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    I was only suggesting this to Kelvin for his future diy build as I think he possesses an anti-mode but not yet a new avr ............if you had the 818 and the anti-mode or a lesser amp as I have what your asking can still be done as long as you have the anti-mode in the chain but to what degree with the subs you have mentioned I don't know as it would come down to how much headroom each sub had with in your room or from each other which governs how much harder one would have to work more than the other..................this is one of the main reasons why its always best to use two subs that are the same and equal in there output and depth.

    But it can still be done though you will be restricted by the lesser capable sub to some degree.
     
  19. GaryL1

    GaryL1
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    Thanks all,
    What I've decided to do. Is to build my own subs, using an 18" cone in each, in a sealed box with roughly speaking a 50cm cube above floor level and the rest of the enclosure underneath, attached to paving slabs placed on the earth about 45cm down from floor level. With the subs being an inverted T shape. The nearest one of these to the back wall is about 90cm from the back wall and 125cm to the listening position (obviously I'll play about with exact positioning before installing). The floor is carpeted, and attached to the underside of the floor boards I'll add 20cm of fiberglass/Rockwool, which should hopefully take out a lot of bass as well as being a thermal insulator. Create a false ceiling out of acoustic tiles about 15cm from the true ceiling (so 225cm down from 240cm). Along the back and front wall in this gap above the false ceiling, fill with fiberglass/Rockwool about 50cm across, as a corner bass trap and similar under the floor at the back for about 90cm. Then also on the back wall to wall corners, add a triangular trap, going 30cm forward and 45cm along the back wall, floor to ceiling. Then add a couple of diffusers on the back wall so the surround dipolar speakers have a chance to do their job. Place furniture/curtains on the walls where first reflections are likely to take place from the front speakers.

    Few questions,
    Is this likely to work to: 1) control the bass decay time, 2) control peaks and nulls, 3) control leakage to outside via the back wall? (By control I mean make a noticeable difference in the right direction).

    Based on this still being a lounge rather than a dedicated HT/listening room, is there anything better I could do without spending thousands, or wrecking the room as a lounge?

    Will the non-bass frequencies suffer from being overly dull?

    Am I likely to cause other artefacts due to the uneven approach to room treatment across all surfaces?

    Will my surround speakers sound as they should with a dead ceiling and just two diffusors on the back wall?

    Is there a way to paint the ceiling tiles, to temper their absorption for mid to highs, so that not all life is taken out of the sound, but some still is?

    Given I turn the system up to get the same average SPL at the listening position (as no longer will have multiple reflections), will the SPL outside of the room be less than before? (I know this is very similar to question 3)?
    This is going to probably take 12-24months for me to complete, mainly due to money restraints (you buy a house that needs a little work doing to it, and invite people around, let them show off by allowing them to do all the jobs you can't do yourself (building, electrics, gas etc.), and then afterwards they want to be paid!).
     
  20. mojogoes

    mojogoes
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    Hi Gary! is there any chance you could put up a pic or diagram just to see exactly where your wanting to put them as on the face of it , it maybe similar as to positioning them in a fireplace.
     
  21. GaryL1

    GaryL1
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    Sorry for the delay. I've knocked two diagrams out, they are done in MS Paint (I don't seem to have any vector based graphics software installed at the moment), the scale is completely off and I can only apologize for the quality.

    Pink circles - the two main listening positions,
    Red rectangles - Front speakers,
    Green Rectangle - Front Speaker,
    Yellow Rectangles - Surround dipole speakers
    (dark) blue - Subwoofers
    Line at front, projector screen
    Two brown lines at rear - diffusers
    Orange rectangle/white triangle - corner bass traps
    Purple rectangle and cyan rectangle - Fiberglass/Rockwall
    Grey line - false ceiling
    Thick dark brown line - floor
     

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  22. Nimby

    Nimby
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    I'd forget the ceiling mods completely. You will soak up huge quantities of bass.
    Which only has to be replaced with more bass if you still want to hear it
    You want to control room modes. Not build an anechoic chamber!

    The accepted way to absorb bass is with tall, deep, fibrous, triangular corner absorbers.
    Start at the rear corners. Add more in front if you feel the need.
    Make the triangles deeper if you need even more absorption.
    Corners are high energy hotspots in the room so bass absorption will be maximised for minimum volume of absorber material.

    If you stand in a corner you will always hear the loudest bass.
    It can be very uncomfortable if you stand (or have to work) in the corner inside a very large building.
    Large shops, stations, offices and factories are good places to try.
    You will be bombarded with nasty infrasonic rumbles if you get right into the corner.
    The same holds true in your room but on a smaller scale at shorter wavelengths.

    Cover the front of your absorbers with a suitable camouflaging cloth to hide the presence of the absorber and to keep fibres from floating in the air.
    Corner absorbers are dirt cheap if you build them yourself.
    Search online for design and construction ideas.

    Use a proper serrated knife rather than a saw on the rock wool or fibreglass bats to keep the dust down.
    Wear a dust mask, goggles and lightweight, disposable, hooded overalls.
    Shower afterwards in lukewarm water.
    Cleaning up rock wool dust may kill your vacuum cleaner. It did ours.
    So its probably best to complete the work outside or in the garage.
     
  23. mattkhan

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    FWIW the equipment you need to verify that a commercial sub is setup properly is the same as the equipment you'd need to verify that a DIY sub is setup properly. To do this you need

    * a PC running REW (or a mac running fuzzmeasure if mac's are your thing)
    * SPL meter (about £15-20)
    * a soundcard with line in/out if it's not built in (about £25)
    * a few cables to connect it up (maybe another £10)

    My point being that the equipment cost of doing this is not the real cost. The real cost is the need to invest time in learning how to make sense of it all. Doing the basics is pretty simple if you can operate a computer & have equipment that is known to work (as opposed to cobbling together some hodgepodge of stuff to do the job that no one else in the world uses) but it can get pretty time consuming.

    Note I said "verify" which means just checking what it is doing. If you want to control that (and for any decent sub, you probably do) then you need some sort of device to EQ it or room treatment that renders EQ completely unnecessary. Assuming you need to give the room some electronic assistance then you're basically choosing between auto eq (something in your AVR or sub, antimode etc) or manual (bfd, minidsp etc). You're largely trading trading time vs money (auto eq tends to be more expensive if bought as a standalone bit of kit) but you're also trading time vs control (auto eq is relatively quick but does what it wants to which is not necessarily what you want).

    On your Q about room treatment, I really suggest posting it on a forum that has some specialists around. The board here sees limited traffic but there are a few posters around who would comment, the american boards see greater traffic on that subject (presumably because their rooms tend to be larger hence more likely to accommodate treatments). The equivalent hometheathershack board is basically run by Bryan Pape (bpape) who is the lead acoustician at GIK Acoustics while the avsforum one has a variety of posters who with a wealth of experience (probably too much judging by the tone of the posts there :rolleyes:).

    The reason I suggest this is because I think you're in danger of ending up with a rather uneven & quite dead room (which you appear to recognise by virtue of asking the Q yourself) by liberal application of material that damps sound waves.

    You also appear to be conflating control of the in room response with transmission (of sound) to the outside world which are different, through obviously somewhat related, things. If you really want to control the latter then I believe the most effective approach is to build a room within a room so that the inner room is decoupled from the outer room but then you're talking about a lounge so that is probably a) overkill, and b) unnecessary for dealing with your transmission problem (if you actually have one).
     
    Last edited: Aug 27, 2013
  24. GaryL1

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    "I'd forget the ceiling mods completely... Not build an anechoic chamber!" Well that's the bit that I think is going to harm the room most as a lounge and be hardest to install so glad you said that. I've been lucky enough to go into Salford Uni's anechoic chamber, would recommend it to anyone to try it but it is weird and not in a pleasant way.

    Unfortunately due to a door way one side and a window the other the front wall to wall corners are not big enough to add anything meaningful into.

    Thanks for the tip about cutting the absorbers, I take it a FFP2 mask, is good enough for this?

    Good point regarding calibration equipment being equal. I've got a PC, ‘top end' sound blaster, REW, cables galore, and an SPL meter, however the meter has only got an onscreen output and is only rated down to 30Hz and can display readings in A and C weighted, can this be used or do I need to get another meter?

    Time is not overly a concern; if I lose a few weekends to get the sound close to the best it can be with all the various restraints of living in the real world, I'll be happy.

    I'd like to treat the room as much as possible while still keeping it as a lounge rather than a studio, so will still need an EQ, would a iNUKE NU6000DSP, give me everything I need, or is the DSP more of a gimmick, where a separate dedicated EQ would produce far improved results? Also calibration wise given I will be using MultEQ-XT32, would it be a good start to calibrate it using Audyssey, mimic Audyssey's graph for the bass section on the sub's amp, then turn off Audyssey and start using REW to fine tune, rerun Audyssey, and then fine tune again on the amp with REW from its new position?

    I have conflated the two issues; for room response, absorption and transmission are good and too much reflection is bad; for deadening the sound to the outside world, absorption and reflection are good, but transmission is bad. So I naively combined the two together and came to the conclusion of absorb as much bass as I can, to cut down on the ‘boom' effect and leakage. You are right I'm not sure if I even have a problem yet, ideally I want to find out before purchase so a) I don't waste money on a system I can't use, b) I don't have a very nice system sat their taunting me, that I can't use.

    As soon as I get my lounge back in use and hi fi gear in place I'll try with my existing sub running a little hot (+2dB) and play War of the Worlds, at roughly -7dB ref and go and stand outside and have a listen. Then try same with rolls of 200mm fibreglass loft insolation in the corner (which is destined for the loft). I'm guessing this is good test leakage wise, as I doubt there are going to be many main stream films that will out do this in the bass department, only problem is the ‘new' subs will be a lot more powerful in the infrasonic and it would be a shame to throttle the system too heavily here to match my existing sub.

    Once I've done this I'll try some other forums on room treatment, thanks for the tips.
     
  25. KelvinS1965

    KelvinS1965
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    Make sure that your sub is up to running War of the Worlds at that level...that was the disc that blew my first Monolith driver, so I've been very wary of it since. :D It was also the one I went outside to see if I could hear it as per my post further back, thinking the same as you that if that one passed muster then any other film would be OK. :smashin:

    I'm looking forward to trying WOTW when I've sorted out my new subs as they will be designed and set up to ensure that they are protected from damage. It will be great to be able to watch something I know has heavy bass and not worry that I'm going to hear a loud 'pop'.
     
  26. GaryL1

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    Is there anyway I will know if I'm close to the limit? Might start at -20dB and stop at -10dB. This is part of the reason I'm going for two 18" cones, rather than 15" or 12" as the speakers should still be in their comfort zone for a level far greater than my comfort zone (same with amp overhead).
     
  27. KelvinS1965

    KelvinS1965
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    I've worked out my DIY sub limits based on modelling in WinISD. This can show the driver excursion depending on what figure you put in the 'signal/input power' box. Since the speakers I'm planing on buying at rated to 1500 watts and the amp can (briefly) produce 2200 watts (IIRC), then I will set the limiter in the DSP section to just below 1500 watts. Given the small volume of both my subs the driver excursion should be within safe limits at 1500 watts, so it's more important not to burn out the driver in my case rather than over extend the travel.

    However, unless you know the volume of your sub cabinet, tuning frequency (if it's ported) and have the driver's details to be able to enter into Win ISD then I don't know how you do this scientifically. Even then it's only because the NUxxxxDSP has the limiter set up shown in watts. I don't know how you could do this using a commercial sub (unless it has a limiter built in perhaps) even if you knew how many watts to limit it too.
     
  28. mattkhan

    mattkhan
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    I suppose you would do it experimentally (like a good scientist :)) and I think you'd need to do this irrespective of what winisd says wouldn't you?
     
  29. KelvinS1965

    KelvinS1965
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    I like to have very clear limits on things (that's why I found video calibration interesting and spent a lot of time learning about it a few years ago). Experimenting seems a bit 'wooly' for my taste, but then I've suffered two blown drivers in the past, so understandably I prefer the scientific approach, with added headroom (just incase). Experimenting based on some previous research would give me a bit more confidence that I wouldn't be damaging the new (expensive) driver.

    While WinISD shows I could hit 2000 watts before hitting Xmax (as opposed to Xmech which my Monolith hit a few times :eek:), so setting the limit to (just) under 1500 watts (for 4ohms) should give me a safe margin since the driver is rated at 1500 watts. In practice I shouldn't reach the limits of these new subs given my normal listening levels, plus if the second sub helps with the null issue then I'll be less inclined to set the sub level 'hot' in the first place. After all it took me 4 years to damage the second driver on just one freak peak. I may even set the dynamic EQ so that by 0dB the signal below 20Hz is reduced by 4 or 5 dB to further protect the driver. Since I generally listen between -10 and-5dB below reference then this shouldn't impact on the sound at the levels I listen at, but will provide a further protection even in the event of a WOTW type high level, single figure LFE blast.

    That's what I hope anyway, but not sure if this really helps the OP, so I apologise for taking the thread off topic. :blush:
     
    Last edited: Sep 3, 2013
  30. mojogoes

    mojogoes
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    I guess one can also argue that your blowing of the monolith driver was more down to its limited to no protection where by the reverse of this would have probably ended your fun much sooner before it had done so..........I've also had subs that in my eyes had too much protection which is even more annoying.:suicide:
     

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