Like

Ok Jonathan id 12 not the max would this be safe

 

Gold Member
Username: Insearchofbass

Post Number: 4294
Registered: Jun-04
I know that image dynamics is known at least in the past for some weaknesses and Im fairly sure this id 12 is the version 2 they made. Anyway as you know I want low extension and high spl is not a necessity sq is the goal here. And to accomplish the sq goal and save space im now considering and infinite baffle set up is what im reading correct that 10 times the vas is what you want to achieve and that the sound quality is excellent with this type of set up? Also I know that power handling is reduced which is also working toward my goal of lower power usage but is this safe in reguards to excursion and any known weaknesses of the image dynamics id 12 v2?
 

Gold Member
Username: Insearchofbass

Post Number: 4297
Registered: Jun-04
bump
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 2010
Registered: May-05
hey sean. i got your other post and replied, but i'm watching all three classes that didn't go on the fieldtrip today. needless to say, they have just caused me to lose all the info i just posted. i'll pick it up again when i get home if jon doesn't post first.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 5464
Registered: May-04
No real bad weaknesses with the sub. The only real problem that the ID 12 had was that it didn't like overpowering very much. I know on the newer models the tinsel leads were pretty close together too, though I've never seen anybody have a problem with it, they are capable of touching together.

The main sub ID had problems with was the first and second version of the ID Max. VERY tight gap to aid BL strength, but it could tend to cause coil rubbing when the sub was driven hard. Also some suspension modifications were necessary. This has been weeded out with the v3, though.

All of IDs subs work very well IB, BTW. 10 times the vas I've never really heard as a recommendation, IB is just IB. No enclosure whatsoever, or at least a large enough space (like a trunk, which is also leaky) that it really isn't a factor.
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 2011
Registered: May-05
hey jonathan. please add caveats where necessary. my understanding is that the sub needs to have a high Q- total and menchanical- in order to be ideal for ib. a sub with a Qts of .35 and above would do well with a relatively high mechanical suspension (Qms). but .4-.7 Qts is what makes for a really good ib driver. conversely, subs with .2-.35 Qts tend to be more boomy with damping issues, unless they have a tight enough suspension. and even then, Q isn't a concrete figure. it drops as the drivers wear and get "broken in". so you want to start significantly higher between about .4 and .7. the id max has a Qts of .34 and a 2.18 Qms. in addition to the boomy response and damping issues, won't they likely need a relatively small enclosure as well?
as for the problem with the max, there is an aluminum ridge around the former of the v3 that prevents the coil from becoming misaligned (like it used to in the first 2 versions), and makes for a more linear motion in such a tight gap at high excursion. was this the addition that was omitted on the previous versions of the sub?
as far as power is concerned, i find it odd that while most profess a more efficient system in ib, buwalda used an additional 300+ watts/sub (UR-12) so that he could have greater control over the drivers. i'm thinking that maybe he noted the low Qts of .3 and figured the power on top of such a rigid suspension would afford better results. of course he was wrong, because he ended up trading those 12's out in exchange for the OA-12's once the Q dropped.
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 2012
Registered: May-05
as a reference, here is the 12-IB4 JL used to make strictly for IB applications.

http://mobile.jlaudio.com/pdfs/8-12IB4_BDS.pdf

notice the high Qts and Qms numbers.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 5471
Registered: May-04
High Qts may or may not be beneficial IB (note I'm referring specifically to a car application). The main thing is the damping at resonance, in which a low Qts sub is going to be overdamped (dry, less resonant) while a high Qts is going to be underdamped (more resonant, more efficient around Fs). What works better is more vehicle dependant.

"conversely, subs with .2-.35 Qts tend to be more boomy with damping issues, unless they have a tight enough suspension"

Other way around. High Qts (tight suspension, weak motor, heavy cone) is more resonant at Fs, thus gains more efficiency at that point. That's why a high Qts sub in a smallish enclosure is so peaky and resonant. Q (quality) factor is basically just quality of resonance, as the number demonstrates the duration of sustain time. Higher numbers indicate a more resonant sub at Fs, while lower numbers indicate a less resonant sub. Example: a Q of 2 yielding a 6db peak at resonance, while a Q of .5 being 6db down at resonance. Basically a low Qts sub will be more efficient up high, but will start to roll off earlier. This can do very well when you take cabin gain into account, at least if you want a flat response. Remember that Qts only defines the driver at resonance.

The ID subs do pretty well IB as far as linearity and low end is concerned.
 

Gold Member
Username: Insearchofbass

Post Number: 4312
Registered: Jun-04
ok since my goal is to save space and an ib would do very well for this and use low amounts of power ill give the infinite baffle a go round hopefully it will meet my expectations sq wise as this is my primary focus and id also assume the sub would drop very low in a ib setup just not super loud which is ok with me I listened 120 db on a quiet morning with one tangband and concluded thats all the loudness i need which id assume the image dynamics would be able to do in this ib setup.....thanks for all your help and input Jonathan and mikechec9
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 2015
Registered: May-05
sounds great sean. keep us posted. now i can hijack your thread:-)

"Q (quality) factor is basically just quality of resonance, as the number demonstrates the duration of sustain time."

sweet. low Qts= large motor, tight response, not so boomy. obviously the total Q is directly proportional to the mechanical (Qts= QmsxQes/Qms+Qes). but since the latter figure also has a direct relationship to the strength of the physical suspension of the sub (spider, and surround), to what degree would a high Qms tend to offset and control the driver's high/loose Qts (or is it not so simple)?
and with a high Qts, doesn't there inherently come a larger enclosure (trunk/ib)?
and last, wouldn't throwing a low Qts sub in such a large enclosure provide a boomy, undamped response?

(clearly, i'm asking in theory as t/s is measured at such low power characteristics change in actual practice.)
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 5474
Registered: May-04
One thing to note, my above post about Qms, I had it backwards. High Qms=loose suspension or heavy cone. I apologize for that one.

The main thing to remember about Qts is that it is a ratio of stored-to-dissipated energy for the entire driver, and tends to be dominated by Qes. A low Qts means a light moving mass, loose suspension, and/or high motor strength. High Qts means a weak motor, a high moving mass, or a tight suspension.

"obviously the total Q is directly proportional to the mechanical (Qts= QmsxQes/Qms+Qes). but since the latter figure also has a direct relationship to the strength of the physical suspension of the sub (spider, and surround), to what degree would a high Qms tend to offset and control the driver's high/loose Qts (or is it not so simple)? "

Both will equally drive Qts up or down if they're varied by the same amount, but Qes tends to vary more than Qms does. The reason the IB4 subs had a higher Qts was because of the high Qms and the high Qes.

The main way to think of this is efficiency. A low Qts sub is more efficient (lighter mass, stronger motor, and/or looser suspension) and a higher Qts sub is less efficient (tighter suspension, weaker motor, and/or higher mass). Remember that Q factor is a ratio of stored to dissipated energy, with values indicating efficiency of the driver.

"and with a high Qts, doesn't there inherently come a larger enclosure (trunk/ib)? "

This is one where you can't go the other way with good results, a large enclosure is required. The enclosure is simply a means to reinforce the suspension (both mechanical and electrical) of the subwoofer. An inefficient sub needs a loose enclosure. You are simply attempting to give a flat response at Fs, and in order to do this you must have a larger enclosure in order to avoid peakiness.

"and last, wouldn't throwing a low Qts sub in such a large enclosure provide a boomy, undamped response?"

Nope. It would have higher damping and a drier response. Basically it would experience a rolloff slightly above Fs. The reason low Qts subs are put in smaller enclosures are to tighten the suspension in order to raise response at Fs, effectively making the subwoofer more resonant at that point. The low Qts sub IB would be less resonant (overdamped) than a higher Qts sub, but it comes with the penalty of having a lack of low end (lack of efficiency at Fs). But with cabin gain, this could provide good results as transfer function would make up for this.
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 2027
Registered: May-05
thanks. makes good sense. i'll play around with (study) this and see how it relates to the different drivers i'm familiar with. then i'll be sure to raise any queries i'm still shaky on.
« Previous Thread | Next Thread »

Facebook

Shop Related Deals

Directory

Main Forums

Today's Posts

Forum Help

Follow Us