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Post by justdhruv on May 29, 2011 13:45:17 GMT -7
I am a complete noob. I came to know about IBs just three days ago, and it has been quite journey aready. After going through the FAQ page and a lot of threads, i discovered that most of the IB Drivers are not available at the moment. The only one available is a Dayton 15" which is supposedly an old design. In this situation, which non IB drivers can be used, and how? Parts-express has a many on sale. including this 18" dayton for $99. www.parts-express.com/pe/showdetl.cfm?Partnumber=295-036i thinking of 2 X 18". Any help and suggestions will be greatly appreciated. |
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Post by ThomasW on May 29, 2011 14:25:10 GMT -7
As it says in the main FAQ, Pro Sound drivers are not a good choice particularly ones with an old school style accordion surround having only 6mm of Xmax.
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Post by justdhruv on May 30, 2011 14:37:25 GMT -7
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Post by ThomasW on May 30, 2011 15:27:58 GMT -7
Don't know anything about them, the Fs is a bit high and I bet the price is too.... First it's not Bill Cowen's IB, it's one he built for friend under contract. And it was built more than a decade ago when there were no other drivers available in Oz Second if you want to use 8-$400 9mm Xmax pro sound drivers by all means go for it. But don't come back here complaining if you find the accordion surrounds are noisy when driven hard. People wanting drivers now might want to look at the Titanic III from Parts Express. It's a nice driver with a reasonable price. www.parts-express.com/pdf/295-420dumax.pdf |
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Post by justdhruv on May 30, 2011 16:16:07 GMT -7
Actually the point was not using 8 $400 drivers. (sorry if i confused with the link posted above) but to use 18" drivers closer to $100-200 range, and not drive them hard, as there are many of them.
I am basically looking for 18" drivers. I will have to import these to India, and i am sure that 2 18"ers will definitely be cheaper to ship than 4 15"ers
So any recommendations there will be really appreciated. So far the only IB 18" driver which seems to be available is the Mach 5 IXL-18.2.2, from their canadian website.
thanks
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Post by ThomasW on May 31, 2011 6:34:05 GMT -7
I think it will be all but impossible to import drivers for $100-$200 a piece.
India is a country that manufacturers lots of raw drivers, is there anything available locally?
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Post by justdhruv on Jun 1, 2011 4:18:08 GMT -7
That is a great idea Thomas.
The problem is that manufacturers here are not very internet savvy, so not many have a website.
I have got hold of a list of manufacturers and suppliers here. I spoke to some of them, but none of them have even heard of the "T/S parameters". They talk in terms of watt, voice coil etc. and frequency response.
It would be helpful if you could list down the parameters important for IB.
I think
Fs 20-30
Q around .5
Xmax not less than 15mm
Rubber foam surround, instead of accordion style.
this was my conclusion after reading through the FAQs and the forums. Please correct me and advise me.
The other problem is that i will have to buy these on specification, rather than any reviews I don't think there is an IB in India. Googling did not bring anything up.
But the price of the driver here is quite low when i factor in freight and custom duties...so i guess i will give it a try. Also i have never owned a subwoofer, so i don't think i will be too disappointed. Hopefully.
Thanks again for all the help.
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Post by ThomasW on Jun 1, 2011 6:53:42 GMT -7
All you need to do is look at the drivers commonly used for IBs to get T/S parameters.
The mfgrs in Inda must understand and use T/S parameters. T/S parameters are the only way accurate way to design an build loudspeakers. Your problem maybe accessing the engineers that work for the companies that make the drivers vs the marketing people selling the speakers.
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Post by justdhruv on Jun 1, 2011 8:08:16 GMT -7
As i said. I don't think there are any IBs in India as yet.
So none of these drivers would have any history of being used in a an IB. But if we know about the parameters, may be one or some of them can make to the required parameters.
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Post by ThomasW on Jun 1, 2011 9:35:13 GMT -7
As i said. I don't think there are any IBs in India as yet. Nothing I've said was referencing installed IB subs in India Via Mikes driver comparison chart (link on this forum) you have access to the T/S parameters of dozens of drivers most of which have been used successfully in IB subs. Print the list, show it to your builder. They should be able to come up with something similar. |
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Post by chrisbee on Jun 1, 2011 22:24:34 GMT -7
If you can find the right driver builder you can tell them there is a global IB market waiting to be filled... But only if they get it right and the price is right.
Reliability of quality and supply still rate very highly in a total driver vacuum. Nobody else seems to be stepping into the breach.
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Post by justdhruv on Jun 2, 2011 2:04:14 GMT -7
That is what I have been thinking as well. Thanks for joining the thread. Chrisbee
Just want to know. Can the T/S parameters of the subwoofer be measured. Is there someone among us who knows how to design a subwoofer driver? Is there any book that one can refer to.
I actually won't mind going to a manufacturer here and sit with him on the design. Here most of the vendors are catering to subwoofers for the DJ Market. They are talking in terms of voice coil size, wattage, etc. How these specification affect the T/S is what I want to find out.
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Post by chrisbee on Jun 2, 2011 10:31:04 GMT -7
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Post by justdhruv on Jun 2, 2011 12:05:26 GMT -7
very true.
While my search for an IB specific driver continues in India, i wanted to the return to heading of his tread: Using non-IB subs in an IB?
The only reasonably priced IB drive available is the Dayton 15" IB. It has a Xmax of 14.3. If i were to import it. it i will cost me $300 per driver. During my survey so far i discovered that, i could easily get 18" drivers for anywhere between $100 to $150.
Now suppose these drivers have an xmax of say 9mm. Don't you think if i use more of them i could possibly get away with them.
The take away from reading the posts on these forums, i have concluded :-
IB subs are high xmax drivers. Since there is little air pressure to resist their movement, they can move very easily to hi excursion, and hence a less powerful amp is required to power them. The design of the subwoofer should be such that it allows for the high excursion.
I remember reading one thread where chrisbee says that ideally the excursion should not be too much and may be of the order of around 6mm. And one should aim to increase the no. of drivers to keep the excursion to very low levels and thus mange low distortion as well.
So my point is, then why not use these ordinary 18" subs with low excursions. Actually i would not mind using 8 of 18" drivers, if i only get low excursions drivers here.
Please let me know if my line of thinking makes any sense.
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Post by chrisbee on Jun 2, 2011 14:07:14 GMT -7
I don't believe I have ever suggested 6mm as a suitable Xmax for an IB driver. It wouldn't make any sense. You may be confused by my suggestion that increasing the total cone area allows much smaller average excursions on programme material.
One still needs adequate Xmax to take care of very low frequency dynamic pulses and extremely high levels. Or accidents with the volume control! The large Xmax is vital insurance against wrecking drivers. They have no air cushion to limit excursion.
I would suggest that 18mm is a suitable minimum Xmax but only from long personal experience using drivers having this parameter.
Your idea of increasing the number of drivers to provide enough total displacement is popular. Particularly with those who cannot source IB drivers locally.
Total displacement is a function of Xmax x cone area x the number of drivers.
The more cone area you can bring to bear the lower the excursion required for any particular frequency and SPL.
You still have to use drivers with a suitable Fs. (free air resonant frequency) My own experience is that an Fs below 20Hz is good. An Fs above 30Hz is very hard work if you want to play sounds below (say) 15Hz.
An Fs of 15Hz provides a naturally flat frequency response down to 10Hz in an IB requiring no EQ in my own experience. (EQ may be necessary to take care of room modes)
An Fs above 30Hz requires a lot of EQ boost to play very low. (again, only in my own experience)
From years of playing films loudly I would suggest you aim for an absolute minimum total displacement of 12 litres. I have reached the excursion limit on action films with 12 litres. Fortunately my drivers survived but it was a shock!
Use much more displacement if you are using very small Xmax drivers and like loud action films. Think in terms of 20 litres total displacement as a minimum.
By keeping the average excursion to a minimum you overcome any non-linearity in the individual driver's performance. You still ought to look for foam, roll surrounds rather than accordion.
If you can find large drivers cheaply enough for your budget then give them a try. You are the guinea pig. Not us. We can't control how you will use them. So we cannot guarantee they will survive. Nor how they will sound. We can only advise you select from the small number of (mainly US) IB specific drivers. (When available)
That does not mean others haven't ignored our advice and used alternative drivers. Thomas is naturally conservative on this issue because he wants everybody to have a working IB with the minimum of problems. The danger is that somebody will use another driver with not enough total displacement. Then bad mouth IBs all over the internet when they break their drivers. Which they will. It's always somebody else's fault when things go wrong.
As usual I suggest you use manifolds to avoid vibration. Manifolds will allow you to pack a lot of cone area into a far more manageable space.
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Post by justdhruv on Jun 3, 2011 8:06:50 GMT -7
Chrisbee, surely you did not suggest the xmax to be 6mm, but you said that the woofers will not move by much. I sort of interpreted it wrongly. But the whole idea of the High xmax is to prevent the driver from damage in a one of peak sometime or the other. Otherwise the excursion of the driver will be pretty low. As you said in a thread that "you can hardly see them moving". Correct me. i am still trying to understand all this.
Ok great news,
I spoke to a guy who manufactures drivers, "He is in a different city of course". He seemed to be semi knowledgable. He was quite curious to know, where i was going to use a 18" subwoofer. Normally he does subs in 10" range. And he does woofers for the DJ market.
I explained to him the basic fundamental of IB, and it seemed that he got the idea.
He is not too much in to the T/S parameters, but he said he will be able to provide the following specs
4'' four layer voice coil
Dual 4 + 4 Ohm nominal impedance
Cast aluminum basket
High grade ceramic magnets
Large spring loaded connectors
Heavy craft pulp cone with thick foam surround
600 watts RMS power handling
22mm Xmax
The voice coil will be copper not aluminium.
Fs he said will be around 18-20.
He is not sure about Q and VAS. I was thinking that i will order one and test it some how... what say?
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Post by ThomasW on Jun 3, 2011 8:57:41 GMT -7
As is discussed in the FAQ there's no need for a big motor structure for an IB driver.
If it saves money VCs in the 3" range are fine and there's certainly no need for stacked big magnets.
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Post by chrisbee on Jun 3, 2011 9:07:05 GMT -7
Excursion is normally low if you can get the total displacement high enough. However, if something silly comes along with ULF mines (like on Bass I Love You) then you can see surprising excursion. Useless flopping about, in other words. Films also contain a lot of ULF pulses. Not all will produce audible effects but you still need the headroom. Your 18" driver sounds very interesting but will depend a great deal on the build quality and T/S parameters. Ideally you need Qts somewhere between 0.5 and 0.7. With an Xmax of 22mm I'd use at least two drivers with an option of two more for extra safety if they are affordable. Once you have the drivers you can test them with REW to confirm some of the claimed parameters. Not to criticise your builder but to help him improve the next batch.  There are all sorts of details to modern driver design which require an element of luck when ordering from a relatively unsophisticated source. At least you will have something to play with. Hopefully without breaking the bank. |
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Post by exipnos on Dec 21, 2011 19:05:46 GMT -7
Your 18" driver sounds very interesting but will depend a great deal on the build quality and T/S parameters. Ideally you need Qts somewhere between 0.5 and 0.7. With an Xmax of 22mm I'd use at least two drivers with an option of two more for extra safety if they are affordable. Hello Chrisbee, Sorry to dig up this old thread. I'm in Europe and I'm looking for cheaper driver here in Europe for an IB install. I started to think along the same lines as justdhruv to use cheaper pro drivers, or more of less capable subwoofers. In your last comment, you recommend at least 2 18" drivers with xmax of 22mm or even 4 drivers for safety. If I calculate this it will give an approximate displacement of 10.6 liters for 4 drivers. Further up in the thread you mention that we need an "absolute minimum total displacement of 12 litres. Use much more displacement if you are using very small Xmax drivers and like loud action films. Think in terms of 20 litres total displacement as a minimum. " Many years ago when the Aespeakers IB15" was available I was going to put an order in for 4 of those based on the recommendation at that time. Correct me if I'm wrong but I guess there are many successful IB installs with 4 IB15 drivers. Calculating displacement for 4 IB15 turns out to be 6.14 liters. I'm currently doing searches for suitable (low budget) driver based on the above minimum displacement of around 6 liters. Should I re-evaluate? |
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Post by chrisbee on Dec 22, 2011 1:31:38 GMT -7
Hi I think you are using Xmax instead of 2 x Xmax x Sd in your displacement calculations.  From memory the original plastic-coned AEIB15 had a claimed Xmax of 15.5mm giving 2.65ltrs per driver. So four earlier drivers offer slightly over 10 litres. The later paper-coned drivers had an Xmax of 18mm providing ~12 litres of displacement. Their safe excursion also exceeds the claimed Xmax. Offering a greater safety margin than other drivers. I reached the limits of my original four AE drivers on some action films. So I (quite arbitrarily) set my minimum recommended displacement at a nominal 12 litres. Which happily matches four of the newer AEIB15s. I have no idea if AE is offering IB15s these days. These are/were excellent IB drivers. Without needing any LF boost to go very low indeed. It is some years since I searched for alternative IB drivers myself. BladeICE in the UK are the distributors for Fi. I think it would be difficult to find similar displacement to the IB318s for the price of any alternative drivers at typical European prices. These drivers are well proven in IB use use and have many happy users around the world. If you a member of AVForums you could try asking if anybody has any alternative IB driver recommendations. A subwoofer forum member called Moonfly is well versed on what is available and interested in IBs himself. He might save you some legwork in your search. It is usually recommended to avoid pro drivers with concertina suspensions because they become noisy at higher excursions. Pro drivers often have a very high Fs. Which normally makes them poor candidates for IB. |
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