Good read for those who belive on modifying subwoofers

[SR]

thanks to a post from soundstream626




I hope this is not considered spamming, but its for educational purposes, before "custom sub builders" sucker you out of your money again. This is from David Moore, Founder and former Half owner of RE Audio. He and Scott Atwell engineered all RE subs ( SX, XXX HC MX, Destroyer etc) before the US Amps buyout:


Quote:
I'm getting more and more ridiculous requests all of a sudden. This is seeming to be becoming somewhat of a problem, not for just us, but other companies that I deal with and talk to often.

We're getting a lot of service requests asking for average subwoofers to be built to handle absolutely insane amounts of power. While we're able to build some very very high powered subwoofers out of existing motors and frames, we are not magicians.

A standard "large" subwoofer with a 3" voice coil is NOT going to handle 3500+ watts reliably on a daily basis for most users! While there are some situations, and some users where this may be SOMEWHAT possible, 98% of the time, it's NOT going to happen.

A basic rule of thumb is as follows:
Most large 3" coil subwoofers can be built to handle anywhere from 0-2500w rms. These types of subs are like the RE MT, DD 9500, fi btl, IA Death Penalty, Nightshade, ETC. In some cases, we can build them to handle around 3000w rms.

Most smaller to medium sized 3" coil subs are going to meet their limits at around 1500-1800w rms. These subs are things like the DD 3500, RE SX, RD Alpha, etc.

VERY large 4" coil subwoofers can be built to handle up to 3500-4000w rms. These are the SS XXX, TC 5400/4HP, TRF, etc.

These higher power handling numbers DO come at a cost though. People ask me for a DD 9500 that handles 3500w rms and "kills on the lows". Guess what? It's not happening!!

By stuffing more spiders into the assembly to handle the extreme power and control excursion of the assembly, you're killing the low end capability of the subwoofer. You're making it greatly LESS sensitive, requiring even more power to get good output from it. Why would anyone want a sub that plays like crap from 40hz and down, just to pour 1000w extra into it and get the same peak output that they would have gotten with a looser suspension and les power?

Basically... when you ask me to do such a build, you're just running in circles. You want the sub to handle more power than it "really" can, and by us doing what we have to do to ensure that you don't destroy it in 5 seconds, you create a subwoofer that performs the same or worse on 3000w than it would have with 2500w or less.

Have you ever really thought about the performance gain from 2500w to 3500w? How much extra output do you think that you will get? In the real world, less than 1db.

This problem is happening because huge amplifiers are getting cheap, and it seems that just because people can run out and buy a 4000w amp, they think that a single subwoofer is going to reliably handle it. News flash... it cant!

While we want to honor your requests for extreme subwoofers, we still want you to be happy with what we end up building for you. Please keep this thread in mind when you send us a request to build your subwoofer.

We'll build anything that you want us to, but we CANNOT warranty a subwoofer with burned leads, ripped parts, burned or damaged voice coils, etc. These are all common failures when using subwoofers with too much power.

I'll be linking far fetched requests to this thread as a response, so if you post in here, make sure it's something helpful. Any silly responses will be deleted.

Thanks guys!
__________________
-David Moore


Take SR`s advice use multiple subs for the kind of output you looking for.

[meccalli]

This is why Scott has...should i say had..Fi, but he designed it so as to be the only online outlet where you can select options to customize and tailor a transducer to suit your needs...let the pros handle it.

[- Rovin's car audio -]

u shud let this thread remain here a while then sticky it


had a very interesting discussion with 1 of d owners of 1 of d biggest stores in trinidad who sells 1 of d most popular sub brands & he was telling me how he knows of customers who bought brand new expensive subs (in d range of $4,000-5000) in his store & their big name unscrupulous installers insist they get d sub modified for additional fee of between $3,000-4,000

d installers taking a brand new sub fresh out d card board box & going by a speaker repair padna to get it "modded" or they themselves "modding" it - they alone know what they doing for 3-4k , thats a average $4500 for d sub + average $3500 modding which means d gullible customer paying close to $8,000 for a "modded" sub when its not really necessary to go through all that , if d dealer & d company that makes d sub tell u that u dont have to go through all that then why ppl are being fooled & taking chain up to spend so much more $ while d "installers" laughing all d way to d bank ...

[dballer]

Nice topic here

[- Rovin's car audio -]

i want to ask this here since rather than it get jumbled in d other thread

what exactly is done to "modify" a sub ?

i'm guessing is it ? :


adding more spiders or spiders made from a "better" material

using a coil that handles more power

a coil that supposedly has more windings or is longer

using thicker tinsel wires

fiber glass or resin d underneath or on top of d cone to make it "stiffer\stronger"

using a thicker material cone

putting on a wider diameter dustcap

machining d gap wider to fit a certain coil or dustcap

adjusting d coil height

using a taller or wider suspension that can travel further

putting a bigger motor on d same frame

raising d basket up higher from d motor allowing for more coil travel

using a taller basket


can somebody shed some light on this ???

is it "trade secrets" so u dont want to say ?

or ppl just hand over d their subs & tell d speaker repair guy to do his thing & u have no clue what he doing ? ...

[OffshoreMarketing]

i never understand why u wud chop upa new sub...if it blow and u burn it down and u wanna experiment fine....

[nervewrecker]

This is why Scott has...should i say had..Fi, but he designed it so as to be the only online outlet where you can select options to customize and tailor a transducer to suit your needs...let the pros handle it.

[shameless insert] David Moore, may be the founder and former half owner of RE Audio but now he is the owner of PSI car audio. iirc he worked for MTX too.[/shameless insert]
David offers quite a lot of option's wrt customizing and tailoring subs to suit ones needs. He even does professional recones and has excellent customer service.
You can see a lot of his work here:

http://www.caraudioclassifieds.org/forum/psi-car-audio/

http://www.caraudioclassifieds.org/foru ... y-speaker/

http://psicaraudio.com/





and is also responsible for the 15" sub in my display pic:



Anyways, I believe the whole modded sub issue is just a hype. A lot of retailers dont know squat about what they sell (many a time I pulled a convo with many a retailer for many big name products and realize they dont know jack sh!t).
Nobody is denying that a sub cant be tweaked slightly to get it to perform in a certain way that a customer may want but the insane power handling requests are just stupid. A sub is made in such a way where there is sufficient cooling for a coil and the suspension allows for a certain amount of travel for the cone. The movements are actually responsible for the circulation of air inside the motor to cool the coil.
A magnet (motor) only has a certain amount of power and is best suited for a coil that can handle a certain amount of power that best matches it. The placement of the coil and amounts of turns in the coil together with the suspension stiffness, motor charge affects the sensitivity.
Putting a coil with more turns = more mass, (affects the sensitivity) and less space in the gap for air to circulate. You now have a bigger coil with increased power handling and heat generation with the cooling ability compromised.
Stiffer spiders or more spiders restrict movement of the cone so you pump more power on it to get it moving. More power = more heat buildup and the cooling capabilities inhibited by the restriction of the movements.
Like I said before, a magnet only has a certain amount of power so there is only so much force to move a coil. Increase the electromagnetic field generated by the coil with more power and there is still only so much the motor can do for you. Even self you put in a coil that can handle x amount of watts there is only so much it can do. By exceeding the power limits you are not only building up heat but there is a limit to the field the coil can generate.
So now you find yourself in a situation where you need a bigger coil / one that can handle more power and a bigger / stronger motor. Basically you talking about a new sub and the $$$ you spending to modify a sub to a certain extent might better be spent on getting one that actually has the characteristics you want rather than leading to premature failure of the one you have. You usually fcuk it up and run go back to your sub wizard and request more out of it and him not knowing what he doing blindly leading you get you to spend more $$$.
As said in the beginning though, some subs can be modded slightly to get a little something different. Some subs use same 'hard parts' so different 'soft parts' can be slapped in and it will work. Take for example the RE SE and SX used the same motors and baskets (hard parts) so you can change the coil in a SE and put something close to 1kw and get away with it. Chances are that your modification is not up to manufacturer spec so you have to drop it on the woofer tester to get the TS parameters to guide you when building your enclosure (another thing that can lead to failure). Modded sub should = modded enclosure, drop a modded sub in the previous enclosure and have your sub wizard on speed dial, you will be visiting him soon again.

[pugboy]

very good info
when you hear a good flea powered full range system(<10)
you will quickly realize power is not everything

[ruffneck_12]

I can understand if its some crappy $85 speaker like Nippon America but...

why would you think the people with all the high tech equipment and years of speaker building know LESS than a garage installer in Trinidad with the best tool in his shed being a multimeter

idk what going on in ppl minds these days

[- Rovin's car audio -]

now there is a big difference with a taking a factory ready made sub & modding it locally as opposed to ordering a sub from a reputable manufacturer with certain modified special features requested from them & they will know exactly what they doing

i'm a bit skeptical of local so i wud choose manufacturer modded instead...

[ruffneck_12]

Yea I rather the manufacturer to handle the modding if it has to be modded

[sMASH]

but why modify it at all? the only reason i can see how modifying a sub makes sense is if it is to be used for a spl system. unless u adding more magnet for greater magnetic flux field and then improving the heat dissipation to compensate for the extra heat generation. but then, just buy another sub that can do what u want it to do.

if u have a certain amount of magnet, then u can have a directly proportional amount of travel the coil could do before it moves out of the magnetic flux field. with that amount moving weight and travel, there is a certain amount of power that would cause the coil to achieve that travel. with that amount of power, there would be a certain amount of heat that would be generated. and with that amount of heat generation, there is a certain design of coil and frame to dissipate the heat.
yes there are things like suspension and coil gap to account for, but that's what the manufactures' r&d departments compensate for with calculations, trial and error.

[carfreak1024]

i can sum up all of your questions for you in a few quick sentences.

When people go to shows and see a certain installer's vehicle performing at a level that they wanna achieve themselves and they then inturn both agree on a price for the whole system, you really think that they gonna care how the man gets it done, they do not care if they spend 10k on a speaker, and 1k on the amp to power it, as longst as they end up with an end result that is what they were looking for in the first place, i am just letting you guys in on the reality of the situation.

Now i am not saying that this is the right way to go about this, because i have seen vehicles built with non-modified subs WIN categories against modified subs both in judged and crowd pleaser. But i have also heard a pair of 10" subs built by one of these same installers, with small power ~5k rated, and it was louder than any other double 10" i have ever heard and it played low too. So to say they don't all know what they talking about, that is something to be debated.

[SR]

so are u saying that enclosure design makes no difference?

[nervewrecker]

all this talk about loudness, power and yadda yadda yadda, have a read:

You can find the difference in SPL by doing this calculation:

10*log(P2/P1) (P1 is power before and P2 is power after)

So, going from 50 watts to 200 watts =

10*log(200/50) = 6 dB

Going from 200 to 300 is really minor:

10*log(300/200) = 1.76 dB

Dropping from 200 to 75 is:

10*log(75/200) = -4.25 dB (you're losing 4.25 dB)

http://www.diymobileaudio.com/forum/gen ... tem-2.html

[carfreak1024]

so are u saying that enclosure design makes no difference?

no that's not what i am trying to say, what i am trying to say is that even though box design does makes a difference some installers rather use other methods to achieve their goals. Sub "modifying" is one of those methods that they choose to use.

Reasons for this are firstly, they choose the wrong subs in the first place; secondly, they tried designing a good box repeatedly and failed; thirdly, music is kinda like racing, the experienced guy tells the customer that his sub is modified or upgraded and the customer is going to automatically think its better; and lastly, sometimes after modifying the subs the old boxes that used to sound crappy now sound GREAT, which ties back in the first 3 reasons.

They build a box for a stock sub not suited for the application they want. It doesn't sound good, then they rebuild the sub, and stick it in the same enclosure and it sounds better or louder, thus the means are justified.

What it all boils down to is that they altered the square peg to fit in the round hole as opposed to choosing the right piece in the first place.