| JinMTVT |
I have just tried a dual "car sub " box on my Bryston
4BST that was given to me by a friend ...
he wasn't able to drive it with any amp at all..
well to be able to drive only 1 sub ( 4ohm ) i had to bridge my 4B to mono output wich gives 800W@8ohm
( ~ 1500W @ 4ohm supposdly )
and i was only barely able to drive it at all with all my sources and all at maximum power ...
now i wonder, why would someone want a subwoofer that is so hard to move?
ain't the point of a loudpseaker to actually move?
i can punch right in the sub without it moving much
( i can't even push it to bottom out )
the suspension is rubber that is probably 1/4" thick
and is hard to even move at all with my finger's nail
please explain .. |
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| theAnonymous1 |
It's so kids can send 5000 watts to their subs at 20hz without the thing bottoming out. Efficiency means nothing when your 18 years old and just want to make noise.
The spider is there to control the cone at low frequencies. At higher frequencies the motor actually controls the cone.
I had a 10" sub in a car once that the spider came detached from. When I played frequencies above 50-60hz the sub played fine; if I went any lower the cone would lose control and start flapping around and bottoming out.
I say sell the thing to some kid looking to make noise and buy yourself something more useful. |
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| JinMTVT |
i never thought about using it at all for myself :p
was just playing with it, and astonished to see that something that stiff can actually give out some sound
I still don't understand the goal of having to push 2000000000 trillion watts in a subwoofer to make some noise ... there must be something more
i don't think that any amplifier that goes up to 2000W+
@ 4ohm can do it with anything less than 1-2%HD
Isn't the goal to try and match the air impedance as much as posisble like when using horns??
that thing is just like 100000000000 times the mass/stiffness of the air to move ..
need more explanation ..still don't get it at all! |
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| impsick |
im no expert on this but obviously this sub isnt gonna hit those lows without hella watts. But it probably hits those low to high mids pretty "stiff". I bet a couple of those subs and a couple more efficient subs would really fill in the tightness and the low end. For like metal, or hardcore metal, or even drum and bass.
I can see where they could be of use. But not worth the hassle maybe.
I dont know but i think for the most part efficient subs sometimes are almost to efficient for the high and low mids. I listen to metal and rock mostly so if you think of a kick drum i like to hear and feel the slap, and the thud, along with the low end of it in the room. |
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| Michael Chua |
| These subs just don't happen to be RED and the brand starts with the letter "V". |
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| theAnonymous1 |
| quote: | Originally posted by Michael Chua
These subs just don't happen to be RED and the brand starts with the letter "V". |
:rofl: Volfenhagen :rofl: |
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| JinMTVT |
nothing written on em ..
i was told by the guy they are from " SWAN" or whatever brand ...i believe that he doesn't even know..
they sure are hell heavy ...probably 150lbs for this 3/4" case and 2 12"
how can it play tight ?
i don't see how a plastic plate ( cause this is what it is ) can play any sound good .. |
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| martin clark |
Don't forget the acoustic environment this thing is supposed to work with is radically different to most room / acoustic issues. It is about achieving high power handling in a cabin, maybe 3cu.m^3, and little else. The cone suspension is designed to be 1)hysteretic and 2) robust, because , with 'cabin gain', it doesnt actually have to be efficient - only to withstand the onslaughts of the nasty amps it will be tested with.
Just my 2c. |
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| anatech |
Hi JinMTVT,
There is a trend to design subs as stiff pistons rather than rely on T/S parameters. The ones I saw could easily support a man's weight without damage. Although the suspension was also stiffer, what you are describing is off the map.
It appears that these were designed to absorb power rather than deliver "music".
-Chris |
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| Mikey p |
| Alot of the "thick rubber surround "car subs are really stiff when they're new. Thet need to "break in" for awhile before they loosen up. If it's an SPL sub it will have a FS in the mid 30's and be built to get loud at one frequency. What may be adding to the stiffness is the subs being in too small a box. It would be intersting to find out what brand they are and see what the T/S parameters are. |
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| anatech |
Hi Mikey p,
For a car, most boxes are too small with an 8" woofer in them. A sealed enclosure then becomes a good alternative if you are after sound quality. If you want a high order box to win SPL events, then I am way out of my element.
-Chris |
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| rcavictim |
Perhaps these were actually part of a large lot of transducers specifically designed to turn ocean tidal energy into electric power and got shipped by accident to a car stereo shop? That could account for the 1/4 inch thick rubber surround.
or...
Maybe this is the device the man stands on when he is about to be launched out of a circus cannon. Again, a shipping error. |
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| JinMTVT |
ahhaha you guys are funny :)
Seriously, i am pumping an estimate of 1500W in 1 of those stupid driver, and i can even get past 60-70db of output for anything under 60-70hz
that has to be ridiculously low efficiency here
Still didn't get 1 reason why those things should exist at all....
i'll try and get some time to remove one of the driver out of the ****** box later on just to see what it is supposed to be |
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| anatech |
Hi JinMTVT,| quote: | | Still didn't get 1 reason why those things should exist at all.... |
Simple. It's a parent's dream (more the neighbours maybe).
This driver will absorb all this power and give low sound output, although it may have great "snap". :D All that juice and no one stays awake.
It is entirely possible that it's a messed up recone or experiment. Could be rejects from off shore manufacturing. Does it really matter, they will be hard to sell unless you make it clear there are no refunds.
-Chris |
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| OzMikeH |
Do your have a really big variac?
They're obviously junk so why not see how much power they can actually handle at 50 or 60Hz.
In short bursts of course. Don't just burn them out. See if they can get any decent excursion across mains voltage.
Be careful
Any pictures? |
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| rcavictim |
| quote: | Originally posted by anatech
Hi JinMTVT,
Does it really matter, they will be hard to sell unless you make it clear there are no refunds.
-Chris |
Yes it appears those drivers will be hard to move.
:xeye: |
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| JinMTVT |
Bah i'll probably try and convince some punks around here that they require "THE" amplifier to actually make sound ..
lol ...what would be needed to send some direct 120v from the wall through them ?
transfo ? i don't have a variac |
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| OzMikeH |
120V into 8 ohms = 15 amps = 1.8 kilowatts
120V into 4 ohms = 30 amps = 3.6 kilowatts.
A 15 amp, 60 volt transformer would me more appropriate. Perhaps a large welder wound up to maximum?
Very dangerous! I was joking.
I doubt you'll have a 15 amp outlet, let alone a 15 amp isolation transformer. Look at the size of the wires in a 15 amp mains extension cord - is the voice coil that big? what about the wires from the terminals to the voice coil?
think of the element in an electric oven, now shrink that element into something the size of the voice coil with the same heat output.
The sub would take about 2 seconds to catch fire, then you have 120V on the chassis. Death!
Similar care should be taken with the outputs on your big amplifier. Music can kill with enough power.
Perhaps the rubber surround was more compliant but it was treated with some inappropriate polish.
Edit: with a 100% efficient amplifier (impossible) 1 kilowatt requires 72 amps at 13.8 volts. In the real world we're talking at least 120 Amps per kilowatt of amplifier. |
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| Michael Chua |
| quote: | Originally posted by theAnonymous1
:rofl: Volfenhagen :rofl: |
12" Dual Voice Coil Car Sub Model: ZX-4712
Manufacturer's Specs (Based on 1 Voice Coil):
Fs = 30 Hz
Vas = 56L
Qes = 0.614
Qts = 0.526
TS measured with LMS (Free Air & Delta Mass-120g)
(Based on 1 Voice Coil)
Fs = 44.3 Hz
Vas = 31.4L
Qes = 3.79 :yikes:
Qts = 2.56 :yikes:
Absolutely ridiculous. Never encountered anything so stiff before. Judging from the thick rubber surround, seriously doubt it can be broken in. Tried emailing but unable to get through :dodgy: Faxing them on Monday regarding discrepancy. |
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| Zero Cool |
car woofers are used by kids that havent got a clue what they are doing or how things work. 9 time out of 10 they are mounted to a board and the back fires into the trunk. The only cabinet they see is the cabin and the trunk.
In these days of 5000+++ watt class D car subwoofer amps traditional woofers dont last long. Kids are into max volume, and who cares about distortion. half the time they crank it up well well WELL into distortion anyway. These ar enot audiophiles here guys.
Car stereo compititions are well into the 170+ db range. i think the record is over 180 actually.
Even most 1000 watt rated pro audio subwoofers wont handle anywhere near 1000 watts down around 20-30hz. maybe a couple of hundred at best.
SO, a super stiff suspension makes sense when there is no back box and it will be seeing 5,000watts plus clipping. and they will. |
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| theAnonymous1 |
| As seen from Michaels post of measured T/S specs; an ultra stiff suspension usually translates to a high(ish) Fs. A 44hz Fs for a 12" driver puts it in the "oversized crappy mid-bass" category; definitely not a "subwoofer". |
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| anatech |
Hi theAnonymous1,
With a woofer that stiff you have to change your thinking. Trow out your concepts of T/S parameters (it's hard to imagine). Now consider that woofer is simply a piston. Similar to those tiny Sunfire subs.
I don't agree with this, but I may be wrong. Several designers have got this concept to work.
-Chris |
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| theAnonymous1 |
| quote: | Originally posted by anatech
Hi theAnonymous1,
With a woofer that stiff you have to change your thinking. Trow out your concepts of T/S parameters (it's hard to imagine). Now consider that woofer is simply a piston. Similar to those tiny Sunfire subs.
I don't agree with this, but I may be wrong. Several designers have got this concept to work.
-Chris |
I understand what your saying, but I was thinking of more traditional automotive designs. Subs like the sunfire use heavy EQ Linkwitz style.
If you put a driver with a 44hz Fs in a normal sealed or vented box and throw it in a car without any EQ, you will be wondering where the lows ran off to. |
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| JinMTVT |
for what it is worth ..( not much )
no brand name
the magnet is 8" thick and this 10" driver must weight something near 50-60lbs alone ..crazy
there seems to be a regular cone type paper under the flat front baffle, the frame is casted alum i believe
and its vented
i can move it approx 1inch in and 1 inch out without distorting the surround rubber ( happens a bit faster going in then out ) and i don't hear anything touching aka coil botomming
neway i'm done with this ****** stuff
still don't undestand the goal of this driver
any buyers?? :D |
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| rcavictim |
Jim,
If you are in toronto I`ll give you $20 for it and I can possibly pick it up. It would make a good frame for some other than audio project I am playing with that needs a moving diaphragm. Send me PM if interested in my offer. |
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| rcavictim |
Jim,
I think theannonymous1 had it right as the one from Partsexpress. Based on the publshed specs it sure sounds like the VC in yours is shorted.
My offer stands since I would plan to put a different VC and metal cone in the driver anyhow for my non-audio experiment. |
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| theAnonymous1 |
| quote: | Originally posted by theAnonymous1
That looks like the HiVi SP10.......
http://www.partsexpress.com/pe/show...tnumber=297-460
If you were closer I would take it off your hands. It would probably do OK in a small sealed box with a Linkwitz Transform and >1000w amp. |
:yell: |
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| OzMikeH |
| quote: | Originally posted by rcavictim
My offer stands since I would plan to put a different VC and metal cone in the driver anyhow for my non-audio experiment. |
Cement mixer? |
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| JinMTVT |
ok!! that is why i was told about Swan ..
i knew i had seen this somewhere ...on parts express
but that was some time ago
so those are the Hi-Vi for sure!!
but why aren't they playing at all ??
there is a problem with those drivers for sure ..
how should i diagnostic that?
and sorry but i won't sell em for 20$ each :p
give me some time to play with them a bit!
what should i do next ?? |
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| Mikey p |
| Test the voice coils and see what readings you get. |
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| JinMTVT |
i have never played with that much
how do i test that?
neway it'll probably have to wait till monday
as my 2 multimeter are all at the job .. |
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| rcavictim |
Didn`t I read that the VC Z was 3.4 ohms or something low like that? If this is the case it is unlikely a consumer cheapo digital multimeter on low ohms scale is going to lead to a conclusive measurement unless one also had a known good speaker at the ready to make a comparison.
A more meaningful test would take some basic test equipment.
Ideally (and the simplest) an LCR meter could be used to measure the VC inductance and compare it to the value posted in the specs.
One could use a variac on the 60 Hz AC line and develop a voltage (start from zero and advance slowly, but not going very high) across the loudspeaker VC and a resistor in series that is the same ohms value as the inductor is supposed to be in reactance at 60Hz. A DMM in low volts AC range is then used to determine if the voltage seen across the VC is the same, higher, or lower than that seen across the resistor. If the same, the VC is OK. If the VC measurement is lower that the resistor voltage the degree of such will indicate if the VC is partially shorted or completely shorted. If the VC reading is higher than that of the resistor the ONLY explanation is that you have chosen an incorrect resistor value for the test, based on bad L value data given in the specs for the driver, or a mathematical error determining the value of the test resistor occurred.
The formula in this application to determine inductive reactance is
1/ [2 pi (60 x L)]
Where pi is not in the oven and L is in henries. :D |
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| djQUAN |
I also have one of them really stiff subs. but I could push the cone in and out with one hand. ;)
I'm using the MOFO 15". although I'm not having the efficiency issue here. I'm getting a lot of low end output (25-40Hz) in a 5cuft 35Hz ported box with about 72sqin of port area.
one thing though, since these subs have really heavy moving mass, I have a big hole at 80Hz (around -10 to -12db). sub is low passed at 80Hz 3rd order.
as others have posted, these stiff subs really do handle low frequencies well. I have driven it to below 10Hz without bottoming out driven at around 800-1kW rms. |
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| rcavictim |
| quote: | Originally posted by djQUAN
as others have posted, these stiff subs really do handle low frequencies well. I have driven it to below 10Hz without bottoming out driven at around 800-1kW rms. |
Those earth tremors were from you? :smash:
I thought we were having a mild earthquake. :D |
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| lolojr1 |
one of the reasons of a stiff suspension is for automotive spl contest style style subwoofers
the stiff suspension is a form of stored energy and it raises the fs making it preform better at a higher tuning, again better for competing
as far as 5ooo crappy watts from a kid as much as i agree it is a form of trickle down theory from company's like dd and atomic who's speakers aren't normally used to play music at all
to some guys its all about 50-80hz and as much power as you can get to a speaker for 3-5 second
they never play music on them and never play for longer than a few seconds
i recently reconed a Digital Design sub with 5 spiders on it all of different thickness's, colors and textures it was one of their top models in their lineup
some of the top competitors recone after just a few uses because the resins used to make the material in the spider stiff break down and they loose the stiffness |
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| badman |
| quote: | Originally posted by theAnonymous1
As seen from Michaels post of measured T/S specs; an ultra stiff suspension usually translates to a high(ish) Fs. A 44hz Fs for a 12" driver puts it in the "oversized crappy mid-bass" category; definitely not a "subwoofer". |
Obviously we're talking about subs here, and specifically this beastie, but let's just be clear- there are plenty of high Fs drivers that are superb, mostly high efficiency pro-style stuff.
Just don't want anyone dismissing drivers based solely upon high Fs.
Those aren't subs, of course, but mid/basses, typically designed to operate up to 1k+. And many aren't crappy, indeed, the high Fs helps make them suitable to horn loading in many instances.
Oh, and the low efficiency SPL-comp style drivers are not high fidelity in any instance I've encountered them. The "Sunfire sub" is a real sack of **** imo. |
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| theAnonymous1 |
| quote: | Originally posted by badman
Obviously we're talking about subs here, and specifically this beastie, but let's just be clear- there are plenty of high Fs drivers that are superb, mostly high efficiency pro-style stuff.
Just don't want anyone dismissing drivers based solely upon high Fs.
Those aren't subs, of course, but mid/basses, typically designed to operate up to 1k+. And many aren't crappy, indeed, the high Fs helps make them suitable to horn loading in many instances.
Oh, and the low efficiency SPL-comp style drivers are not high fidelity in any instance I've encountered them. The "Sunfire sub" is a real sack of **** imo. |
Sorry badman, again my train of thought was on automotive drivers with a high Fs due to the stiff suspension. These make crappy "subwoofers" IMHO.
I didn't mean to lump high efficiency pro drivers in to the bunch. Pro drivers usually have a high Fs because of their relatively low moving mass which translates into better transient response and higher efficiency. |
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| jnb |
| quote: | Originally posted by theAnonymous1
Pro drivers usually have a high Fs because of their relatively low moving mass which translates into better transient response and higher efficiency. |
Thank you, I was wondering that. Could you mention the disadvantages of this when using pro drivers for HiFi? |
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| rcavictim |
| quote: | Originally posted by jnb
Thank you, I was wondering that. Could you mention the disadvantages of this when using pro drivers for HiFi? |
Harder or impossible to get really deep bass extension even with 15 and 18 inch drivers. Cabinets are often larger. The resultant much improved efficiency and reduced distortion however is the reward.
Also a `disadvantage` for those that plan to keep their quality speakers for a lifetime, the surrounds are not cheap, stupid foam and will last forever in home use and then still be entirely fine to those who inherit them 50 years from now. Oh what, that is actually another `advantage`. :smash: |
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| pinkmouse |
Just a thought- yesterday I was servicing several stacks of Turbosound Floodlight PA gear. One lowmid 12" driver was producing very low volume and distorting, so I pulled it out and put it on the bench. On further inspection, the magnet had shifted, (due to being dropped I assume), and the cone was virtually solid - even putting all my weight on the cone it wasn't moving perceptibly, just flexing around my fingers.
Could this be your problem? |
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| rcavictim |
| quote: | Originally posted by pinkmouse
Just a thought- yesterday I was servicing several stacks of Turbosound Floodlight PA gear. One lowmid 12" driver was producing very low volume and distorting, so I pulled it out and put it on the bench. On further inspection, the magnet had shifted, (due to being dropped I assume), and the cone was virtually solid - even putting all my weight on the cone it wasn't moving perceptibly, just flexing around my fingers.
Could this be your problem? |
No, he reported that the cone moved in and out freely with no cone or VC rubs. Just stiff. |
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| theAnonymous1 |
| quote: | Originally posted by rcavictim
No, he reported that the cone moved in and out freely with no cone or VC rubs. Just stiff. |
Which leaves.......
1) The voice coil is shorted.
2) The driver really is just a black hole for wattage.
3) 1 + 2 |
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| badman |
@ Anonymous1: No need to be sorry, I knew you meant that type of driver specifically. The reason I posted was for the benefit of those like jnb.
| quote: | Originally posted by rcavictim
Harder or impossible to get really deep bass extension even with 15 and 18 inch drivers. Cabinets are often larger. The resultant much improved efficiency and reduced distortion however is the reward.
Also a `disadvantage` for those that plan to keep their quality speakers for a lifetime, the surrounds are not cheap, stupid foam and will last forever in home use and then still be entirely fine to those who inherit them 50 years from now. Oh what, that is actually another `advantage`. :smash: |
Agreed re: efficiency and distortion (though i don't have measurements, more conjecture, to back me up)
I'm not quite sure I follow your meaning in the bottom paragraph, do you mind rephrasing? Pro surrounds usually are tougher than nails, and I think this is what you mean, but want to be sure. |
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| rcavictim |
| quote: | Originally posted by badman
I'm not quite sure I follow your meaning in the bottom paragraph, do you mind rephrasing? Pro surrounds usually are tougher than nails, and I think this is what you mean, but want to be sure. |
Huh? I mean FOAM BAD. It rots. Bye bye speaker investment. While it is rotting the speaker characteristic is changing. Pro drivers with their corrugated treated cloth or otherwise corrugated surrounds last virtually forever. I absolutely REFUSE to pay hard earned money for any driver that has a foam surround. IMO the entire DIY audio community should boycott that garbage. If one needs the higher excursion that is the only benefit of foam you can get it with a long lifetime in a modern synthetic rubber roll surround (neoprene, santoprene, etc.). If the market refused to buy this carp these holeasses would stop making it! Hello!
There does that help clarify my stand? You were just edging me on weren`t you?! :D |
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| badman |
| quote: | Originally posted by rcavictim
Huh? I mean FOAM BAD. It rots. Bye bye speaker investment. While it is rotting the speaker characteristic is changing. Pro drivers with their corrugated treated cloth or otherwise corrugated surrounds last virtually forever. I absolutely REFUSE to pay hard earned money for any driver that has a foam surround. IMO the entire DIY audio community should boycott that garbage. If one needs the higher excursion that is the only benefit of foam you can get it with a long lifetime in a modern synthetic rubber roll surround (neoprene, santoprene, etc.). If the market refused to buy this carp these holeasses would stop making it! Hello!
There does that help clarify my stand? You were just edging me on weren`t you?! :D |
Well, maybe a little bit ;)
However, modern foam surrounds aren't quite so bad as you make out, they often have treatments applied to keep them working properly as they age (within reason). Sometimes foam is chosen for reasons other than excursion and affordability. The surround plays a major role in a driver's behavior. Audax PR17OMO has a foam surround, the flat ring surround probably wouldn't work as well with other materials.... it's about as well-regarded a driver as there is.
Badman- rebelling against absolutism since.... whenever. |
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| jnb |
| quote: | Originally posted by rcavictim
Harder or impossible to get really deep bass extension even with 15 and 18 inch drivers. Cabinets are often larger. The resultant much improved efficiency and reduced distortion however is the reward. |
As the cones are thin, what about breakup? Pro cones often have ribs which I figure smooth the upper response, making it useable. Would you know how I could estimate where even this breakup begins to occur. |
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| DevilDriver |
| quote: | Originally posted by rcavictim
Huh? I mean FOAM BAD. It rots. Bye bye speaker investment. While it is rotting the speaker characteristic is changing. Pro drivers with their corrugated treated cloth or otherwise corrugated surrounds last virtually forever. I absolutely REFUSE to pay hard earned money for any driver that has a foam surround. IMO the entire DIY audio community should boycott that garbage. If one needs the higher excursion that is the only benefit of foam you can get it with a long lifetime in a modern synthetic rubber roll surround (neoprene, santoprene, etc.). If the market refused to buy this carp these holeasses would stop making it! Hello!
There does that help clarify my stand? You were just edging me on weren`t you?! :D |
1. Most foam-based surrounds are now treated. Not perfection, but a reasonable approach.
2. Foam is more compliant.
3. Foam is less expensive.
4. Foam is less prone to changes in compliance over time, though all mechanical systems are at least a little prone to these problems.
There is nothing about a foam surround that makes it inherently awful to use for a speaker and to suggest otherwise is rather asinine in my opinion. |
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| rcavictim |
| quote: | Originally posted by DevilDriver
1. Most foam-based surrounds are now treated. Not perfection, but a reasonable approach.
2. Foam is more compliant.
3. Foam is less expensive.
4. Foam is less prone to changes in compliance over time, though all mechanical systems are at least a little prone to these problems.
There is nothing about a foam surround that makes it inherently awful to use for a speaker and to suggest otherwise is rather asinine in my opinion. |
Neil,
Your comment #3.
If you have to pay the same price as the driver cost initially to get the surround replaced after 15 years how is foam less expensive?
I see many home speakers at the local landfill site with rotted out foam surrounds. If they had not been made of foam they would likely still be in use and the owners better off financially and the planet a bit better off too.
As far as you thinking my comments being assenine. Well you are welcome to them and my opinion of foam surrounds stands.
:smash: |
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| aduljr |
*Power handling: 500 watts RMS/700 watts max *VCdia: 3" *Le: 1.35 mH *Znom: 8 ohms *Re: 3.4 ohms *Frequency range: 35-150 Hz *Fs: 34 Hz *SPL: 84 dB 2.83V/1m *Vas: .60 cu. ft. *Qms: 4.83 *Qes: .65 *Qts: .57 *Xmax: 15.5 mm *Dimensions: A: 10-1/4", B: 9-1/4", C: 5-11/16".
That has to be a defective driver or a mistake. |
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| Taterworks |
| How about using it as a driver in a big pro-style bass horn? It seems like the stiff suspension would enable it to withstand a ton of punishment, while that incredibly strong motor would work well for driving the horn itself. In fact, from what you described, this would be a perfect driver for a bass horn, with the exception of that crazy-high Qts. |
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| richie00boy |
| Which of those parameters makes you think there is a mistake aduljr? |
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| mikee55 |
I used to have a 12", where I could unbolt the magnet. It had no dust cover and never made a sound. Everyone who saw it said how they admired my lampshade :cool: . I glued the coils support ring, which was metal, to the cone and hung it on my ceiling rose. I was young and single back then. Wouldn't have one now!:D
Mike:D |
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| Richard Ellis |
Barring any defects in this driver, what you have is the pinnacle of the Car-audio gang.
The drivers used are nothing more than an electric powered gong,....one note response, grossly ineffecient & not really truely designed for MUSIC.
My RS 12" dual coil sub-woofer is rated for 60WPC (Each coil), at that power level she'll run some half inch or so of travel...moving plenty of air & accurate as well.
Get something else if you want to play music thru it.
If you want to hear good low clean bass, listen to the last thirty seconds of U2s' "Its' a wonderful day"
________________________________________Rick........... |
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| ocool_15 |
| quote: | Originally posted by Richard Ellis
If you want to hear good low clean bass, listen to the last thirty seconds of U2s' "Its' a wonderful day"
________________________________________Rick........... |
Do you mean Beautiful Day? |
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| Richard Ellis |
Yeah.....brain lapse I guess.........
__________________________________Rick......... |
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| JinMTVT |
ok i got my nice multimeter tonight at home
it has a position with a "coil" picture
wich seems to be in "H"
wich i guess is "henries" ??
can i use that to test the drivers?
please instruct me on how to test those POS
:p |
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| Taterworks |
| That's an inductance meter, as you correctly inferred. It tests the impedance of a coil at 1kHz to develop an inductance value. I'd suspect your delta-mass parameter measurement, because the mass needs to be very rigidly affixed to the cone, not just placed on it. You essentially need to sacrifice one and glue a weight onto the cone. |
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| JinMTVT |
| quote: | Originally posted by Taterworks
That's an inductance meter, as you correctly inferred. It tests the impedance of a coil at 1kHz to develop an inductance value. I'd suspect your delta-mass parameter measurement, because the mass needs to be very rigidly affixed to the cone, not just placed on it. You essentially need to sacrifice one and glue a weight onto the cone. |
is it ok to say that i dind't get ANYTHING of what you just said ??
i dind't try anything yet ...
got the multimeter and the drivers
what should i do now ?
i won't glue something on the cone dude!
:p |
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| jnb |
| If you're looking for a shorted voice coil, measure the resistance across each coil (on your DMMs lowest resistance range), then measure between the coils (on one terminal of each) and post the results. :) |
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| JinMTVT |
mmm
i don't get it
there are only 1 set of terminals on the driver
not 2
how can i test "between the coils" then ??
please explain more so i can get on with that
i have measured 3.8-4.2ohm with on the driver connections at rest
as soon as the move the cone with my hand though,
that all goes to havoc ...goes up to a few Mohms ...
is that normal ?
then i tried the inductance on my multimeter
gives pretty much nothing at rest
and changes alot when i move the cones ..
let me know what's next |
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| JinMTVT |
and i am not necessarly looking for a shorter coil
i am looking for anything wrong with those
as i can't get even 1 to play more than a few db
with my 4B bridged to 1000W+ @ 4ohm |
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| jnb |
My mistake, I assumed it was a dual voice coil unit, just ignore the 'between the coils' bit.
4 ohms doesn't sound like a shorted coil. Maybe the electrical side of things is OK. If you don't feel rubbing, then the driver may not be broken.
BTW, avoid moving the coil with an ohm meter connected as this applies a voltage to the meter which could possibly damage it.. |
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| JinMTVT |
hi!
ok ..i guess i dind' thought it would produce voltage strong enough to dommage my MM
what other tests can i do ???
i mean ..i can't even make it sound like a sub
with the 4B ..i don't get it |
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| jnb |
| Well, it's worth noting that the f3 will be somewhere in the 50Hz range at best for a closed box. This is OK for a car as there is cabin gain to augment the rolloff. |
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| rcavictim |
| quote: | Originally posted by JinMTVT
hi!
ok ..i guess i dind' thought it would produce voltage strong enough to dommage my MM
what other tests can i do ???
i mean ..i can't even make it sound like a sub
with the 4B ..i don't get it |
Try a different amplifier. Maybe the Bryston has issues with the lowZ reactive load.
Put flying leads on the speaker terminals (clip leads if you have) and momentarily connect the driver to a 12 volt car battery, one polarity and then reverse and again. See if the cone moves. If it does not your driver is totally skee-rude. You should see a small spark as the lead is removed from the battery and hear a fairly loud click from the speaker cone. |
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| anatech |
Hi JinMTVT,
It's entirely possible some electrolytic caps are going open. I have seen this in a few Bryston 4B's now. No shock as they are old enough.
Time to recap your Bryston.
Also keep in mind that some boxes will simply not behave.
-Chris |
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| JinMTVT |
ok .the Bryston plays just perfectly fine on my other loudspeakers ..
is there any measurements i could seriously do on the drivers to have an idea of the possible causes ??
still waiting for advices..
i'll probably unmount the other driver this week end
and see if i can ge *** to play on another amp
anbd take some measurements at the same time!
anything will help as far as the measurements go .. |
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| rcavictim |
| quote: | Originally posted by JinMTVT
ok .the Bryston plays just perfectly fine on my other loudspeakers ..
is there any measurements i could seriously do on the drivers to have an idea of the possible causes ??
still waiting for advices..
i'll probably unmount the other driver this week end
and see if i can ge *** to play on another amp
anbd take some measurements at the same time!
anything will help as far as the measurements go .. |
OK. Get yourself a tape measure and take he diameter and depth measurements so you will know what to buy at the store to replace these blown drivers. You have had plenty of technical advise already about what `measurements` and procedures you can use to evaluate the failure mode of these drivers already in this thread from folks wishing to help which you seem to ignore. Good luck. |
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| JinMTVT |
I don't want to keep those bastards,
i want to sell them back
but if they are blown, it'll probably be a little hard to do
as far as measurements..i am noob
and i haven't understand correctly what to do from any of the 2-3 measurement indication posts on this thread yet!!
:p |
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| JinMTVT |
i just tried them on the Bryston 4B again , on single channel but with the 2 drivers in paralell ...( 2ohm)
played a bit louder...but at everything maxed out or almost , it was probably 1/4 as loud as my 2 12" in my current setup
but the sound seems correct
can there be any problem that causes that kind of behavior?
can drivers really be that ineficient?? |
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| rcavictim |
| quote: | Originally posted by JinMTVT
can there be any problem that causes that kind of behavior?
[/B] |
Abuse as a child? |
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| JinMTVT |
| quote: | Originally posted by rcavictim
Abuse as a child? |
ahahaha
nice one :p |
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| jnb |
I don't design drivers but I know they can take any set of compromises a designer wants to put into them.
I was just re-reading this post by theAnonymous1 and couldn't help but think it would just make things so simple.
Hope it works out :)
| quote: | Originally posted by theAnonymous1
It's so kids can send 5000 watts to their subs at 20hz without the thing bottoming out.
I say sell the thing to some kid looking to make noise and buy yourself something more useful. |
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| Naudio |
heres the problem
84 dB 2.83V/1m
that means u need over 1000w of REAL power to get these to 104db/spl
might be ok in a small space like a car, but i still don't see why they make drivers this hard to drive
also that 84 dB 2.83V/1m may be 8th space efficency in witch case your screwed
i like to hear my bass
:cool: |
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| rcavictim |
| quote: | Originally posted by Naudio
heres the problem
84 dB 2.83V/1m
that means u need over 1000w of REAL power to get these to 104db/spl
might be ok in a small space like a car, but i still don't see why they make drivers this hard to drive
also that 84 dB 2.83V/1m may be 8th space efficency in witch case your screwed
i like to hear my bass
:cool: |
And there is really no excuse for the outrageously poor efficiency either since large magnet structures (high field strength in gap) are what is required to make high efficiency possible (besides some other no brainer factors like not physically damping the cone so it cannot move!), and this driver certainly does have a large magnet structure. |
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| anatech |
Hi Bob,
One thing that needs to be considered is that often, woofers are sold on magnet size and their ability to dissipate power. Selling intelligent woofers for car applications halted many years ago.
Same for amplifier sound quality. Most are not listenable these days by our standards. The poor young fellas don't have any idea anymore.
-Chris |
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| AndrewT |
| quote: | Originally posted by anatech
The poor young fellas don't have any idea anymore.
|
Admit it, we were all the same when we were young. We only acquired some sense when we grew up. |
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| anatech |
Hi Andrew,
Well, no. I took a different path.
When I was young, "Mind Blasters (?)" were the high power rage. Echo boxes and 8 tracks. I installed a pair of efficient 12" woofers on some plywood where the back seat used to be. A '67 Cutlass with a monster trunk (box). At about 4W, it pounded. Later on I installed an "MGT 2100". Supplies of +/- 34 VDC. You want to believe that car was loud. Later on I actually designed proper boxes using 8" woofers (about 2,000 cu in each) with mids and tweeters. From there I was always loud and clean. Even when the other poor guys were using "Fosgate PR-250(?)" amps. Those supplies were only about +/- 22 VDC and they couldn't figure out why I had more power, and cleaner power.
Ever see a "Linear Power" amplifier? Some of those ran +/- 45 VDC supplies and higher. Too bad the amps didn't sound good. They believed that MJ15015 and MJ15016 were audio outputs. The amp sections were enough to make big noise. Did warranty on those briefly.
-Chris |
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| JinMTVT |
Ok thanks all again
let's assume here that my problem resides in the fact that those POS are seriously unefficient
since they are working if i put everything to the max
Now onto real stuff
how can i modify those massize woofers so that they will become alot easier to drive ??
what determines efficiency in a drivers like that?
i don't care if i have to put the scalpel through it,
i think that this massize magnet structure deserves something better than this stupid setup
tell me what to do, and i'll try and work it out!! |
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| theAnonymous1 |
I once modified the spider of a driver I considered to be too stiff. I cut sections out of the spider until I ended up with what looked like a wheel with 5 spokes.
The drivers I did this to had a fairly soft surrounds though. Your at the disadvantage that the surround is probably just as stiff as the spider. |
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| penderaudio |
From what I've heard and seen about the specs on this driver, it realy only has one use and that is for SPL car audio comps. I'm a formmer DB Drag world finalist in 2004, and have seen many drivers similar to this one.
This sub Idealy would be used in a small ported box, tuned high-50-65 hz in a small hatch back car ( Honda CRX is one of the perfered vehicles.) The goal is nothing other than coupling the tuning of the box with the Fs of the car. Now that you have mated frequencys, the idea is to give as much possible power now say 3000-5000 watts depending on how much 12V power you can supply.
Basicaly you have a one note wonder! The suspension is stiff to deal with the amount power and have some cone control in a box that has noth to do with the T/S parameters but the acoustics of the Car used. Hope I'have shown a little light on the subject. |
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| Naudio |
| quote: | | Same for amplifier sound quality. Most are not listenable these days by our standards. The poor young fellas don't have any idea anymore. |
| quote: | | Admit it, we were all the same when we were young. We only acquired some sense when we grew up. |
this may apply to your typical thick boy racers, but not for me
when i get a car i want to design a nice bass horn for it, then cruse up next to the boy racers and drown out their crappy 3000w(yer rite) low efficiency setups.
am not entirely sure how bass horns perform in cars though, from what i hear about cabin gain im not sure there necessary |
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| Naudio |
theres your answer, insert the speaker into a bass horn, that will boast its efficiency the odd 10db+, and is sure to work better than mutalating it
i think there are designs available if you have the determination to actually get that thing hearable
----------------------------------------------------------------
not how i would design it, but you get the idea..
http://www.cardomain.com/ride/2387835/1 |
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| anatech |
There are always people who will design for enjoyment and fidelity. That is a lasting system. then there is all the stuff designed to separate people from their cash.
It was pretty cool selling, installing and servicing audio when it was breaking. We all learned a lot. Then it all seemed to go down the tubes.
I have a Nak TD1200 somewhere and my TD700. Those were the days. I think I even still have my Concord HPL-200. $550.00 (I think) new for an AM/FM cassette (sendust head).
Those speakers would best be sold possibly to some bright eyed youth. Good drivers can be had for less money. Getting an 8" into a car in a B4 box is a challenge. It's worth it though. Look for good home audio drivers. The earlier Vifa woofers used to freeze when it got cold. I didn't believe it either - 'till it happened to me!
Getting a 10 " into a car with a B4 alignment will be next to impossible. I'd rather run 4 8" drivers in that case anyway.
-Chris |
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| JinMTVT |
ok
i thought that there would be something to do with this massive magnet ..like probably compeltly recone + new suspension + new spider ??
else i'll just sell this stupid box to some kiddoes at work
is it at least possible to use this crazy magent and redo the driver design somehow ? |
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| penderaudio |
From my experence bass horns don't really work in cars very well because the size of them usally effects the natural resonation of the vehicle. In all reality they really are not needed beacuse of the amount of cabin gain you get in a vehicle.
Also, for shere SPL you don't need an efficient driver because the vehicle itself is so efficient at a certain frequency.
For example In a Honda CRX "As mentioned before" will be louder with two 10" drivers in small ported boxes then 4 15" Drivers with the same amount of power. I know it sounds wierd but do some research on the loudest street drivable vehicles "www.termpro.com" and all the lower "street classes" are dominated by setups like these.
What is also interesting is that a small car with 2 10" drivers and 5000 watts will do around 160 db and larger vehicles with 2-3 18" drivers and 20-30000 watts will only be 3-4 db louder on average.
I'm not trying to defend the kid's running around ratteling windows, that is alot different than competive car audio. I'm just trying to say there is a purpose for all different kinds of drivers. |
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| Naudio |
| wow i had no idea that car cabin gain was that drastic, :eek: |
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| jnb |
| quote: | Originally posted by Naudio
wow i had no idea that car cabin gain was that drastic, :eek: |
Cabin gain is like room gain, only it happens at a higher frequency due to cabin size. |
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| penderaudio |
This also the reason why it is so hard to get a car to sound good and have flat frequency response. Then throw in the reflective surfaces (Windows, Windshield) into the mix and things get real crazy.
Near flat low frequency response in a car, is usally done with heavy EQ and Low tuned, Low FS drivers. Similar to a nice home driver, Not the SPL machine you have.
One last issue is the size of the vehicle, if you have an SUV 30hz response is attainable and strong, in a small car 40hz might be the low end, say a 12/db rolloff, even if the box in open air has an F3 of 28 or 30.
Peerless makes an XLS mobile audio sub that is fantastic. |
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| spudfrog |
| If the driver is really that undesirable, your best bet is to sell it whole and buy something different. The time/energy/money spent trying to find a suitable recone (not to mention one that will suit your needs) will probably not be worth it. |
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