Brett said:
Concrete boxes? There will already be several good size boxes for the mains so I am not sure we want any more... I think we have basically decided on an IB. The IB shouldn't cost too much, 16 * $35 = $560 (or 32 = $1120)
In terms of construction cost, the owner is a professional builder, so building manifolds or strengthened walls etc would not be too hard, and the extra materials aren't expensive in the context of building a house...
Thanks for the idea but I can't do everything, think I'll stick with the IB...
cheers, DB
ThomasW said:
Thanks for the advice, we may be able to change the room dimensions...
ThomasW said:
Well - I'll take that to mean that you think it would work but that it isn't something that you would do... It is actually a (home) bar so a solid wood wall covered in speakers would in my opinion be a nice feature.
ThomasW said:
Again, thanks for the advice, I'll check that out.
ThomasW said:
Please don't shoot me down here I'm just trying to learn something...
You obviously know a lot more on this subject than I do... as you say, one way of looking at the effect of a LT circuit is that it modifies the driver Qts and Fs.
Another way of looking at it is that it is an EQ circuit that applies a gain pattern to the input signal tailored that a specific driver.
You said that as the drivers are low Qts they will need EQ to bring up the bottom end.
If I find an EQ circuit that happens to provide the gain pattern that I need then why should I not use it?
As I said, you know more about this than I do so perhaps the only reason is that it is hard to get a LT circuit right and a simple EQ is easier.
cheers, DB
I've just been evaluating one of the jarcar 10" drivers. Fed 9v (close to 5w I think) sine wave at 20hz it goes to 8mm peak to peak. This is probably a bit over its xmax although I'm not sure.
There seems to be a little distortion and suspension noise, although not too much - I don't think I would be enough to be annoying as I can hardly hear it at 3m or so, I don't really know how much noise to expect when treating a driver this way although the noise coming from this seems reasonable... also I think some of it is coming from the back but that wouldn't be audible in an IB.
There seemed to be some minor rattles and squeaks up above 60hz or so, perhaps the spider resonates a bit at certain frequencies??? For the record it sounds quite respectable in a sealed box.
I am leaning toward the conclusion that it would be suitable for an IB system provided lots are used; thoughts ???
cheers, DB
There seems to be a little distortion and suspension noise, although not too much - I don't think I would be enough to be annoying as I can hardly hear it at 3m or so, I don't really know how much noise to expect when treating a driver this way although the noise coming from this seems reasonable... also I think some of it is coming from the back but that wouldn't be audible in an IB.
There seemed to be some minor rattles and squeaks up above 60hz or so, perhaps the spider resonates a bit at certain frequencies??? For the record it sounds quite respectable in a sealed box.
I am leaning toward the conclusion that it would be suitable for an IB system provided lots are used; thoughts ???
cheers, DB
Firstly about drivers. There is more to consider than cost and output! If you buy a lot of cheap and nasty drivers rather than a few good value quality drivers, you can easily end up with something impressive looking, loud yet quite a bit less impressive in terms of SQ.
I recall the first time I listened to Jaycar subs. They had their JV60 kit on display with the Vifa P17 in a vented box. Listening to them vs the bass from any of their subs, it was clear that none of them were close to musical. The Vifa kit was good, but the subs they had, all of them were terrible in comparison, a big step backwards. This was around 2004, back then I couldn't imagine wanting that sound, and I'm fussier now. Some of those 12" drivers were worth $300, just slightly less than you would pay now for a Tempest. The beauty of the Jaycar drivers is that you can evaluate them easily. However, unless they have changed dramatically, I wouldn't use any of them. I did build a 10" sub for my parents, built for $150 including amp. It was just to add some bass to their TV.
The point I'm getting to is that you must first start with decent drivers. Cheap and nasty drivers won't suddenly become better when used in large numbers. They will always be limited by their inherent weaknesses which will persist no matter how many of them are used. Yes you will get an incremental improvement by reducing the load to each one, but you will find that a decent driver will sound better. Even fed with lots of power and moving at xmax, a decent driver will get a better result than a pile of dodgy drivers barely even moving.
If you are talking about the best performance for a given amount, then it may make more sense to chose a number of decent drivers over a large and very expensive uber driver. However, I'd suggest starting with drivers which have a certain level of quality. If budget is restrictive, then start with less of them, and add on later. I think this makes sense for two reasons:
1. You won't be held back by their SQ
2. You have a more logical upgrade path - no need to sell drivers
I'd suggest as a minimum you look at drivers like Peerless SLS or XLS which are very good value here. Both work well with a fairly high crossover point, easily 80 Hz. The XLS is tending to be overlooked these days, being an older driver and not so impressive now with its xmax of only 12mm. However, if you look at the measurements, it's distortion in the 40-80Hz range is very low. Within its limits it has excellent performance, it appears to still be more articulate than most of the new drivers.
Many sub drivers won't do it, and if you try to cross around 80 Hz the sound is awful.
The new Tempest X drivers also look very good.
Regarding construction, timber framed plasterboard walls are good for taming room modes - they tend to absorb the bass. They are also good for letting the bass get through! Are the studs already in place? Hardwood is a pest to work with. If you have an old house with F8 OBHW it makes life so much more difficult! The timber gets dry and hard, unseasoned when originally built, but now very different. Pine is so much easier!
If you can influence the construction, then it makes sense to do a few things like sealing up any gaps and trying to at least get two a skin either side of the stud which is continuous - no holes or openings. Easier said than done. Then acoustic insulation and ideally more than one layer of plasterboard, joined with liquid nails which remains flexible and gives you some bass damping.
I did this with my home theatre reno, and I was surprised to notice two things:
1. Much less bass gets out - I don't have to worry about neighbours
2. Much more bass stays in - dramatic increase in impact
I recall the first time I listened to Jaycar subs. They had their JV60 kit on display with the Vifa P17 in a vented box. Listening to them vs the bass from any of their subs, it was clear that none of them were close to musical. The Vifa kit was good, but the subs they had, all of them were terrible in comparison, a big step backwards. This was around 2004, back then I couldn't imagine wanting that sound, and I'm fussier now. Some of those 12" drivers were worth $300, just slightly less than you would pay now for a Tempest. The beauty of the Jaycar drivers is that you can evaluate them easily. However, unless they have changed dramatically, I wouldn't use any of them. I did build a 10" sub for my parents, built for $150 including amp. It was just to add some bass to their TV.
The point I'm getting to is that you must first start with decent drivers. Cheap and nasty drivers won't suddenly become better when used in large numbers. They will always be limited by their inherent weaknesses which will persist no matter how many of them are used. Yes you will get an incremental improvement by reducing the load to each one, but you will find that a decent driver will sound better. Even fed with lots of power and moving at xmax, a decent driver will get a better result than a pile of dodgy drivers barely even moving.
If you are talking about the best performance for a given amount, then it may make more sense to chose a number of decent drivers over a large and very expensive uber driver. However, I'd suggest starting with drivers which have a certain level of quality. If budget is restrictive, then start with less of them, and add on later. I think this makes sense for two reasons:
1. You won't be held back by their SQ
2. You have a more logical upgrade path - no need to sell drivers
I'd suggest as a minimum you look at drivers like Peerless SLS or XLS which are very good value here. Both work well with a fairly high crossover point, easily 80 Hz. The XLS is tending to be overlooked these days, being an older driver and not so impressive now with its xmax of only 12mm. However, if you look at the measurements, it's distortion in the 40-80Hz range is very low. Within its limits it has excellent performance, it appears to still be more articulate than most of the new drivers.
Many sub drivers won't do it, and if you try to cross around 80 Hz the sound is awful.
The new Tempest X drivers also look very good.
Regarding construction, timber framed plasterboard walls are good for taming room modes - they tend to absorb the bass. They are also good for letting the bass get through! Are the studs already in place? Hardwood is a pest to work with. If you have an old house with F8 OBHW it makes life so much more difficult! The timber gets dry and hard, unseasoned when originally built, but now very different. Pine is so much easier!
If you can influence the construction, then it makes sense to do a few things like sealing up any gaps and trying to at least get two a skin either side of the stud which is continuous - no holes or openings. Easier said than done. Then acoustic insulation and ideally more than one layer of plasterboard, joined with liquid nails which remains flexible and gives you some bass damping.
I did this with my home theatre reno, and I was surprised to notice two things:
1. Much less bass gets out - I don't have to worry about neighbours
2. Much more bass stays in - dramatic increase in impact
Hi Paul !
Thanks for your comments, I think you have made a number of good points.
I did some sims, and for 32 of the 10" s above had about the same max output as two 15" tempests and about the same cost. The main difference was in efficiency, so > 10x amp power is required!
Your comments about distortion levels make sense to me, I think I can live with the lower efficiency. Fewer drivers make for an easier install too. I'll check out the peerless drivers you mentioned when I get the time... who sells them here?
It would be quite funny if the neighbors complained because the house is in the middle of a 100acre block in the bush... we'll do our best though!!!
Construction of the room in question has not yet started, I'll pass on your suggestions regarding construction. I assume the techniques would work just as well with cement sheet?
What about cement sheet with wood panels installed over it?
The system will be used 2/3 for music and 1/3 for HT. How many of the Tempest 15s would I need (2, 4 etc), is there a simple driver displacement / room size rule of thumb to work this out?
cheers, DB
Thanks for your comments, I think you have made a number of good points.
I did some sims, and for 32 of the 10" s above had about the same max output as two 15" tempests and about the same cost. The main difference was in efficiency, so > 10x amp power is required!
Your comments about distortion levels make sense to me, I think I can live with the lower efficiency. Fewer drivers make for an easier install too. I'll check out the peerless drivers you mentioned when I get the time... who sells them here?
It would be quite funny if the neighbors complained because the house is in the middle of a 100acre block in the bush... we'll do our best though!!!
Construction of the room in question has not yet started, I'll pass on your suggestions regarding construction. I assume the techniques would work just as well with cement sheet?
What about cement sheet with wood panels installed over it?
The system will be used 2/3 for music and 1/3 for HT. How many of the Tempest 15s would I need (2, 4 etc), is there a simple driver displacement / room size rule of thumb to work this out?
cheers, DB
I've had great luck with low priced drivers in cars IB, though HT is not exactly the same. The Fs/Qts is important because that is in essence your enclosure tuning, in a way. I'm of the school that you tune the subs to your use and then EQ if you have to, not the other way around as is common today. I used to use pyramid originals, but have not since there were upgraded. Quality seems to be higher at lower excursions IMHO, so moving more air (larger/more drivers) helps but I'm not sure about as many as you are thinking. Your gains diminish after about 4 I think, what I usually run in a car.
Right now I am using an infinity 300wrms sub in a car IB, it seems to work well. With about 100wrms each it is powerful and overpowers the high side of the system so much I rarely turn them up. Even if I do I get maybe half of xmax. They do say in the manual half of rms ratings for IB use. But I am considering changing out to the cheaper drivers, they will be much lighter (4 of these is really heavy in car), and with more efficiency I am thinking I will not lose that much db, and I can run a smaller amp to boot. If you need huge output then cheap driver may not work for you. But in my experience the gains of high power and HD driver is not that much with IB as with enclosures...you still run out of xmax with IB.
Most HT go with 15s even 18s that I have read about, larger tends to give you free efficiency and lower Fs that helps you. In a car you get cabin gain that lowers your curve so 10s and 12s work better than in a house. If you have a wall of subs that big, you need to anchor it to concrete or something that is why manifolds work nice. I just model a huge sealed box to show IB in software. Anything that dampens will help the wall, such as drywall, concrete, MDF, even filling the wall with sand...think heavy. A manifold will cancel the physical movement more and cause less mounting issues.
Right now I am using an infinity 300wrms sub in a car IB, it seems to work well. With about 100wrms each it is powerful and overpowers the high side of the system so much I rarely turn them up. Even if I do I get maybe half of xmax. They do say in the manual half of rms ratings for IB use. But I am considering changing out to the cheaper drivers, they will be much lighter (4 of these is really heavy in car), and with more efficiency I am thinking I will not lose that much db, and I can run a smaller amp to boot. If you need huge output then cheap driver may not work for you. But in my experience the gains of high power and HD driver is not that much with IB as with enclosures...you still run out of xmax with IB.
Most HT go with 15s even 18s that I have read about, larger tends to give you free efficiency and lower Fs that helps you. In a car you get cabin gain that lowers your curve so 10s and 12s work better than in a house. If you have a wall of subs that big, you need to anchor it to concrete or something that is why manifolds work nice. I just model a huge sealed box to show IB in software. Anything that dampens will help the wall, such as drywall, concrete, MDF, even filling the wall with sand...think heavy. A manifold will cancel the physical movement more and cause less mounting issues.
broughd , 4x 15" tempests should do the trick nicely, as paul has stated the qaulity will be there , also they'll take a lot more abuse than cheap drivers ( ib's need to be able to handle big transiets in a ht ) , you can power these with a behringer ep2500 for about $680 and you'll have a sub that will be very gutsy for a room that size
cheers ken
cheers ken
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