I'd like to know whether anyone has ever attempted to remove one spider from dual-spider pro drivers in order to increase Vas and lower fs a little.
I.e. making them more usable for HiFi purposes.
An alternate possibiliy may be buying defective ones and reconing them with only one spider in place instead of two.
I am aware that one might increase the risk of coil-rub and one will probably mess around with the linearity of the compliance (apart from probably killing the driver during the surgery due to having four left feet).
The only place whare something in this direction has been discussed is this thread:
http://www.diyaudio.com/forums/multi-way/67672-spider-surgery-anyone.html
The difference is that the OP from said thread attempted to remove parts of oa single spider instead of one complete spider in a multi spider arrangement. I find the mutilation of a spider more risky then removing one out of multiples. But maybe I am plain wrong.
Regards
Charles
I.e. making them more usable for HiFi purposes.
An alternate possibiliy may be buying defective ones and reconing them with only one spider in place instead of two.
I am aware that one might increase the risk of coil-rub and one will probably mess around with the linearity of the compliance (apart from probably killing the driver during the surgery due to having four left feet).
The only place whare something in this direction has been discussed is this thread:
http://www.diyaudio.com/forums/multi-way/67672-spider-surgery-anyone.html
The difference is that the OP from said thread attempted to remove parts of oa single spider instead of one complete spider in a multi spider arrangement. I find the mutilation of a spider more risky then removing one out of multiples. But maybe I am plain wrong.
Regards
Charles
I have done this, thinking that I could change the parameters of a sub to make it more suitable for my needs. I cut out more than half of the spider.
Most T/S parameters changed. The mass, SD and BL doesnt change, and these are key parameters. So when I simulated the sub in a bass reflex with new T/S parameters nothing really changed compared to before the surgery.
What is it about pro drivers that you want to change?
Most T/S parameters changed. The mass, SD and BL doesnt change, and these are key parameters. So when I simulated the sub in a bass reflex with new T/S parameters nothing really changed compared to before the surgery.
What is it about pro drivers that you want to change?
There was once a time when there were lots of 12" and 15" drivers avialable that were something between hifi and PA. Fostex and Coral for instance manufactured some of these. Nowadays such drivers are hard to find (TAD is one very expensive example).
Nowadays many PA "subwoofer" drivers often offer good linearity and quite high xmax along with meticulous build quality. But very often the compromise between LF extension and efficiency is geared towards high efficiency. So it would be interesting to lower fs a little in order to achieve better extension.
Adding weight would also be a possibility but that is rather suboptimal IMHO.
Exchanging corrugated surrounds for rubber or foam ones would also be a possibility. But they both have disadvantages (rubber offers the least optimal cone termination in terms of reflections and foam has the known rot problems).
Regards
Charles
Nowadays many PA "subwoofer" drivers often offer good linearity and quite high xmax along with meticulous build quality. But very often the compromise between LF extension and efficiency is geared towards high efficiency. So it would be interesting to lower fs a little in order to achieve better extension.
Adding weight would also be a possibility but that is rather suboptimal IMHO.
Exchanging corrugated surrounds for rubber or foam ones would also be a possibility. But they both have disadvantages (rubber offers the least optimal cone termination in terms of reflections and foam has the known rot problems).
Regards
Charles
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Well, changing the spider isnt going to give you more extension. Weight can. If you add weight to a PA sub it can bring down Fs and efficiency in the midrange giving a flatter response. But in that case I would rather buy a sub with more xmax to start with. It will have more mass and lower Fs too...
Sorry but I don't want a sub - I want a woofer. Maybe I caused some confusion due to mentioning "PA subwoofer". But the LF capable PA drivers are often called subwoofer in PA terminology when they would rather be called mid-bass in HiFi Terms. But HiFi subwoofers can't be used up to the midrange like the TAD and similar ones could.
And it is not about X-max - most modern PA drivers have enough of it and they also have enough midrange - but they lack alittel in LF extenion for my taste.
Regards
Charles
And it is not about X-max - most modern PA drivers have enough of it and they also have enough midrange - but they lack alittel in LF extenion for my taste.
Regards
Charles
Ok, then I really dont understand. PA has great woofers.
You still havent written down any numbers or any actual info. so I will be waiting for a proper question.
You still havent written down any numbers or any actual info. so I will be waiting for a proper question.
I actually own a few pieces of the neo version of the 12S330 - the 12N630. And I will take two per side for a three way (it is a subwoofer after all - I would not use it higher than 300 Hz). And yes, one can go very low with this one in quite compact boxes. But I wouldn't mind using a lerger box with a driver that is more efficient.
But I am also interested in a 15" that could be used for a two-way with a large horn (or maybe a three-way with a BMS coax horn driver). There are many nice drivers out there like the JBL 2226 but if one wants to go below 40 Hz things are getting difficult. Something like a JBL 2235 or a TAD 1603 would be even nicer. But the first one is difficult to obtain and the second one is extremely expensive.
There are some modern drivers that are indeed very sexy. Like the Beyma 15LX60 that could be used in a B6 tuning that is going to below 30 Hz. Or the Eighteensound 15nlw9500 which has a low fs, double shorting rings and a very low lvc for a woofer like that. Unfortunatley no one ever seems to have measured its distortion and CSD plot.
12nlw9300 looks tempting for an MTM with its fs of 40 Hz. But its Qts around 0.25 doesn't help for low tunings. Since I am going active I could of course use some current feedback in order to increase Qts via Re.
Regards
Charles
Didn't know how high you need it to go and the 12S330 is quite limited in that respect.
The 12S305 doesn't go quite as low but it seems to add a lot of ability further up in return.
BMS themselves spec them as 25-300 & 35-2500 respectively although I'd take the 2.5K with a (large) pinch of salt.
A bit OT but how would you rate the S330/N630 for a woofer up to 300Hz?
I've got this future project whizzing through my head which requires a 12" crossed at 250Hz or so. Do you know of any better or cheaper (or both!) alternatives?
The more I look around the less interest I have for traditional HiFi drivers and their manufacturers and the more I have in pro drivers. These days I find myself only looking at tweeters from HiFi. For mids and woofers the pro guys always seem to have the better option. Recently I used the little Faital 5FE120 which turned out to be a stunning little midwoofer and not just for the ridiculously low price of £20 delivered.
The 12S305 doesn't go quite as low but it seems to add a lot of ability further up in return.
BMS themselves spec them as 25-300 & 35-2500 respectively although I'd take the 2.5K with a (large) pinch of salt.
A bit OT but how would you rate the S330/N630 for a woofer up to 300Hz?
I've got this future project whizzing through my head which requires a 12" crossed at 250Hz or so. Do you know of any better or cheaper (or both!) alternatives?
The more I look around the less interest I have for traditional HiFi drivers and their manufacturers and the more I have in pro drivers. These days I find myself only looking at tweeters from HiFi. For mids and woofers the pro guys always seem to have the better option. Recently I used the little Faital 5FE120 which turned out to be a stunning little midwoofer and not just for the ridiculously low price of £20 delivered.
I haven't tried them so far - unfortunately. I guess I will cross them over somewhere between 200 and 250 Hz. As mid I will probably use a 18sound 10nmb420 because I want a mid with high efficiency and I also like if it is doing low excursion only therefore the size. For tweeter I will go with a XT1086 waveguide. HF driver still undecided.
The most likely arrangement will be WTMW due to the use of a low-mid crossover that has very low group delay distortion but that comes with inferior lobing properties than an LR4.
Regards
Charles
The most likely arrangement will be WTMW due to the use of a low-mid crossover that has very low group delay distortion but that comes with inferior lobing properties than an LR4.
Regards
Charles
Thanks Charles,
sounds like an interesting project.
Any comments on the S330/N630 once you've used them will be hugely appreciated!
sounds like an interesting project.
Any comments on the S330/N630 once you've used them will be hugely appreciated!
Look at this piece from Steen Duelund: http://duelundaudio.com/wp-content/uploads/sites/3621/2013/12/cab_units_and_room.pdf
He recommends burning holes in some spiders to prevent closed cavities under the spider. But maybe you could do it for both spiders to keep the center function but still lower damping force.
He recommends burning holes in some spiders to prevent closed cavities under the spider. But maybe you could do it for both spiders to keep the center function but still lower damping force.
Twin-spidered pro drivers tend to be vented between the spiders and have a vented pole piece so no closed cavities and no need to burn holes.
That's why I suggested it may be helpful to his original quest in another way,
eliminating one spider seems like a worse idea than weakening both spiders.
The other part was the original thought of needing those holes. And yes, that does not apply here 😉.
eliminating one spider seems like a worse idea than weakening both spiders.
The other part was the original thought of needing those holes. And yes, that does not apply here 😉.
Another problem about removing one of the spiders in a dual spider design is, the question of mechanical stability. Most of those drivers employing dual spiders are designed that way, so the two spiders have a centering role, besides making the suspension stiffer. If you remove one of them not only the T-S parameters change, but the uniform pistonic motion of the cone suffers too, so it is much more likely that sooner or later voice coil rubbing will occur, ruining the driver eventually. Don't forget, those drivers use rather heavy cones, so with vertical mounting gravity skews the cone and its its parallel motion.
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