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My Tumult sucks (v. Don't believe the model / What to do with a paperweight?) - Page 2

post #31 of 90
Quote:
Originally Posted by Stereodude View Post

I'd say the most telling characteristic is that the sub lacked impact and slam. I'd play a track I was familiar with and wonder where the kick to the bass was.

I see. I think this is most important since out ears determine the fate of a finished product and not a measurement. I submit that the sound you were hearing had nothing to do with inductance. If anything, the peak should have assisted in your overall output. From an audible perspective, if this inductance peak bothered you, it should have manifested itself as some form of bloat at worst. No one can really accurately decipher sound quality differences because of inductance at low frequencies like what we are dealing with here. Those who say they can probably have that special oxygen free speaker cable and those tip-toes of a certain angle that also improve sound quality.

I think if you rebuilt the box you would be able to achieve the sonic output you initially wished for.

Best,
Mark
post #32 of 90
Thread Starter 
Quote:
Originally Posted by mrogowski View Post

I see. I think this is most important since out ears determine the fate of a finished product and not a measurement. I submit that the sound you were hearing had nothing to do with inductance. If anything, the peak should have assisted in your overall output. From an audible perspective, if this inductance peak bothered you, it should have manifested itself as some form of bloat at worst. No one can really accurately decipher sound quality differences because of inductance at low frequencies like what we are dealing with here. Those who say they can probably have that special oxygen free speaker cable and those tip-toes of a certain angle that also improve sound quality.
I never said it sounded bad due to inductance. It sounds bad because the frequency response of the box sucks and the upper bass is many dB too quiet.
Quote:
I think if you rebuilt the box you would be able to achieve the sonic output you initially wished for.
Rebuilt it how? What's wrong with the construction of the current box?
post #33 of 90
post #34 of 90
Thread Starter 
Quote:
Originally Posted by bossobass View Post

First, no, the AV driver did not compete with the Tumult. 34 mm bests 23 mm by 2 to 1 at 20 Hz in a sealed system.
First of all, when did I say the AV competed with the Tumult in the marketplace? Oh that's right, I didn't. I said the AV15-H spanks my Tumult in this box.
Quote:
Of course, maybe I didn't have 4 of each here and maybe I didn't test them exhaustively. rolleyes.gif
I wasn't aware anyone claimed otherwise, but thanks for sharing.
Quote:
Your close mic free-air is not accurate.
I haven't a clue how you can say that. It might not match your Tumults, but there's no evidence that the measurement is wrong for my Tumult. The same 30Hz hump is present in box and free air with a similar roll off above 30Hz in both. There is a strong correlation between them.
Quote:
Read what Seaton said. Anyone who uses a computer to design a system and expects it to match the sym is a deluded rookie, like yourself. You should have asked your question BEFORE you built.
First, I never said I expected to match the sim. I would expect some level of correlation. I get that correlation with the AV15-H. I don't get that with the Tumult. Second, you have totally twisted Mark's point in an attempt to attack me. Mark advocated exactly what I have done. Measuring instead of blindly trusting the model. Mark didn't say anything like what you have attempted to attribute to him.

You know, your experience with the Tumult could be useful here. For all I know something is wrong with my Tumult. But, instead of offering useful and thoughtful feedback based on your vast experience with the driver, you take my post personally like I insulted your mother and go off on an anti AV15 rant and resort to posting childish insults instead of helping. You're definitely the sort of first class poster we all should emulate! rolleyes.gif
Edited by Stereodude - 10/8/12 at 8:08pm
post #35 of 90
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

didn't we already discuss this?
http://www.avsforum.com/t/1432586/close-mic-measurements-of-a-passive-radiator-sub
Sort of... I wanted to make sure I had an accurate & trustworthy measurement before starting a thread specific to the driver where my measurements would be called into question.
post #36 of 90
"But, instead of offering useful and thoughtful feedback based on your vast experience with the driver, you take my post personally like I insulted your mother..."

maybe not his mother, but perhaps one of his children.

bosso sells subs and has raved about how great that driver was/is. maybe some of his systems had the tumult in them.
post #37 of 90
I just don't understand the constant condescension. It's baffling, really. Look at the difference in tone between the 2 posters on this thread who are considered real experts. Both give good information, but one, as ALWAYS, is delivered with a sneer. I don't get it.
post #38 of 90
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

bosso sells subs and has raved about how great that driver was/is. maybe some of his systems had the tumult in them.
That's all well and good, but this thread is about my Tumult. Not his Tumults and not the Tumult in general. I don't see the reason for all the consternation on Bosso's part. The Tumult isn't sold anymore. It's not like this thread is going to hurt his ability to sell his subs or make his personal subs sound worse. Frankly, I'm suspicious that mine is defective / damaged in some way but I can't prove it.
post #39 of 90
Dayum. There is a lot of anger in this thread. What gives?
post #40 of 90
Thread Starter 
Quote:
Originally Posted by Scott Simonian View Post

Dayum. There is a lot of anger in this thread. What gives?
It's AVSforum. Though even I have to admit I'm a little surprised how quickly it turned into a crap show.
post #41 of 90
Quote:
Originally Posted by Stereodude View Post

I never said it sounded bad due to inductance. It sounds bad because the frequency response of the box sucks and the upper bass is many dB too quiet.
Rebuilt it how? What's wrong with the construction of the current box?

Hmm... I could have sworn you were focusing in on the frequency hump you measured. No matter...

It is obvious the driver isn't producing what you were expecting of it in the box you built. So modify/change the box to improve your output. You do have the parameters to go by now don't you?
post #42 of 90
Close mic in a sealed 3.0 cu ft box. No EQ, just a 80hz XO provided by my receiver....

Sorry, my photo wont load, something has changed with the new AVS site, stand by.....
Edited by kgveteran - 10/9/12 at 11:37am
post #43 of 90
Quote:
Originally Posted by Stereodude View Post

It's AVSforum. Though even I have to admit I'm a little surprised how quickly it turned into a crap show.

No, it's you. You've always had this childish adversarial posting style, which is obviously why you've learned little about sub building.

Dragging my mother into your thread is typical of your offensive approach to any discussion.

Your Tumult vs mine or anyone else's? Get real. The evidence is that both Ilkka and I measured the Tumult in a sealed box to within (+/-) 1dB, years apart. It rolls off -7 to -8dB from 50-100 Hz. That means it will roll off LESS than that in free air. You're showing a -10dB drop. Your in-box shows a -18dB drop. Not bloody likely. Your F3 should be below 20 Hz, regardless of Le roll off.

So, you want someone here to diagnose your problem a close mic free air measurement and tell you what the problem is?

Here it is, FWIW:

1) Inspect the driver for mechanical problems; glue joints, dust cap, spider, leads, surround, offset, cone sag, etc. The driver is a decade old and apparently sat unused for that amount of time.
2) Put it in 100L sealed and check the close mic with a known reference, Ilkka's GP measurement, to narrow the search for the problem.
3) Measure the T/S parameters using REW and following the instructions or search Lilmike's REW T/S thread.
4) Come back with the data and lot less of your usual added BS like 'sucks' and 'paperweight'.
post #44 of 90
Thread Starter 
Quote:
Originally Posted by bossobass View Post

Your Tumult vs mine or anyone else's? Get real. The evidence is that both Ilkka and I measured the Tumult in a sealed box to within (+/-) 1dB, years apart. It rolls off -7 to -8dB from 50-100 Hz. That means it will roll off LESS than that in free air. You're showing a -10dB drop. Your in-box shows a -18dB drop. Not bloody likely. Your F3 should be below 20 Hz, regardless of Le roll off.
Well, yours is consistent with Ilkka's. Mine doesn't seem to be.
Quote:
So, you want someone here to diagnose your problem a close mic free air measurement and tell you what the problem is?
Here it is, FWIW:
1) Inspect the driver for mechanical problems; glue joints, dust cap, spider, leads, surround, offset, cone sag, etc. The driver is a decade old and apparently sat unused for that amount of time.
I visually inspected it before starting the thread. It looks / seems fine. FWIW, the driver was "stored" vertically mounted in a box.
Quote:
2) Put it in 100L sealed and check the close mic with a known reference, Ilkka's GP measurement, to narrow the search for the problem.
Well, I don't have 100L sealed box just sitting around waiting for me to test with, but I'll consider making one and testing if I have spare time.
Quote:
3) Measure the T/S parameters using REW and following the instructions or search Lilmike's REW T/S thread.
I've measured the driver with the Dayton DATS already. Is there some reason to believe that REW will make a higher fidelity or more accurate measurement?

DATS Measurement: (Click the thumbnail for full size)

post #45 of 90
Quote:
Originally Posted by Scott Simonian View Post

Dayum. There is a lot of anger in this thread. What gives?


It's because you haven't started your mega build yet and we are tired of waiting. mad.gifmad.gifmad.gifmad.gifmad.gif















I don't really see anything wrong with the measurements of this system. Other than there are none from the listening position. This driver is probably a version 1 working just fine. The tummie exhibits about an 8dB roll off to 100Hz from a peak near 40-45Hz in a 100L sealed box. He shows a few DB more roll off but as I have mentioned earlier a close mic does just this so that is consistent with what you would expect. OP has it in a much larger passive radiator system also. The larger airspace will lower the frequency of the peak and the PR tuning will also boost the low end and perhaps shift the peak down slightly as well. He listens to it and thinks it sounds like warmed over a$$. That could be because of the raw FR shape being rolled off up top giving a bottom heavy ,slow sound or his room acoustics could be doing who knows what. It is no secret that a flatter more extended top end (louder too) will sound cleaner and more detailed to the ear. Bottom line get some EQ capability and bring the top end up to match the bottom and knock out that peak. Then measure at the listening position. If there are bad issues get the EQ out again and go to work. Listen again. Still hate it? Sell it and move on.
post #46 of 90
Quote:
Originally Posted by Ricci View Post

It's because you haven't started your mega build yet and we are tired of waiting. mad.gifmad.gifmad.gifmad.gifmad.gif

That's not true. I've started it. I just haven't finished it. wink.gif

It's pretty close. Surprises are fun! biggrin.gif
post #47 of 90
Hi Seth,

One last thought to double check/confirm. With the various iterations over time, I don't have confident parameters handy, and I don't recall if the D2/D4 coil option was during or after your Tumult. Is your version a DVC? If so, please double check that both are showing the same DCR. If not, is the DCR close to what the specs suggested?

Beyond that, it boils down to needing EQ and more power to get more performance from it. If you don't have power to push past the AV15's capabilities, then there's no need for the Tumult.
post #48 of 90
Thread Starter 
Quote:
Originally Posted by Mark Seaton View Post

Hi Seth,
One last thought to double check/confirm. With the various iterations over time, I don't have confident parameters handy, and I don't recall if the D2/D4 coil option was during or after your Tumult. Is your version a DVC? If so, please double check that both are showing the same DCR. If not, is the DCR close to what the specs suggested?
I have a dual 2 ohm voice coil option. I measured both of the coils separately with the DATS as well as the series measurement I posted, but they're on a different PC I don't have with me. I will check them later.
Quote:
Beyond that, it boils down to needing EQ and more power to get more performance from it. If you don't have power to push past the AV15's capabilities, then there's no need for the Tumult.
I will break out the DSP-30 later, but the amount of power needed to overcome what I measured is going to be beyond what I have.
post #49 of 90
Thread Starter 
Quote:
Originally Posted by Mark Seaton View Post

Hi Seth,
One last thought to double check/confirm. With the various iterations over time, I don't have confident parameters handy, and I don't recall if the D2/D4 coil option was during or after your Tumult. Is your version a DVC? If so, please double check that both are showing the same DCR. If not, is the DCR close to what the specs suggested?
DCR of coil a is 1.344 ohms. DCR of coil b is 1.309 ohms. The impedance graphs are pretty similar between the two.

post #50 of 90
Quote:
Originally Posted by Stereodude View Post

DCR of coil a is 1.344 ohms. DCR of coil b is 1.309 ohms. The impedance graphs are pretty similar between the two.

Do you have a pic of the driver not in the enclosure
post #51 of 90
Thread Starter 
Quote:
Originally Posted by kgveteran View Post

Do you have a pic of the driver not in the enclosure
Sure...

post #52 of 90
Holy freakin' top plate, Batman!
post #53 of 90
scott, the top plate is not solid (at least i don't think so). it appears to be kind of a "bumped" top plate which moves the top plate up, so the coil can have more excursion before hitting the back plate--an alternative approach to the bumped back plates that you've seen.
post #54 of 90
Try 300-500grams, it won't play as low but you might be more happy with the results up top.

If that doesn't do it for ya, then you will need to build some PA subs. High excursion subs tend not to do very well above 40hz; which is where 75% of the chest resonating bass is. The stuff under 40hz is for breaking your wife's china collection via earthquake pulses biggrin.gif
Four ~1500g PR's with a high excursion type sub is best used for the latter, rather than the former.

What amp are you using BTW? 40-100hz usually takes a good deal of power to reproduce accurately, at least a bridged EP4k or a single channel from a FP10kQ or similar...
post #55 of 90
Thread Starter 
Quote:
Originally Posted by BassThatHz View Post

Try 300-500grams, it won't play as low but you might be more happy with the results up top.
If that doesn't do it for ya, then you will need to build some PA subs. High excursion subs tend not to do very well above 40hz; which is where 75% of the chest resonating bass is. The stuff under 40hz is for breaking your wife's china collection via earthquake pulses biggrin.gif
Four ~1500g PR's with a high excursion type sub is best used for the latter, rather than the former.
The PRs are pretty much not adjustable anymore. The mass (A bolt with many washers and nut) was added to the cardboard tube on the back and stuck there permanently with expanding foam. I will take some more measurements later, but I think for now the AE AV15-H is going to let me have my cake and eat it too. I still want to quantify how much SPL I'm giving up down low with the reduced excursion though.
Quote:
What amp are you using BTW? 40-100hz usually takes a good deal of power to reproduce accurately, at least a bridged EP4k or a single channel from a FP10kQ or similar...
I'm using a QSC PLX2402 bridged for my testing. It can drive the Tumult past the point of audible distress (which I think might be caused by the tinsel leads slapping the cone, but I'm not sure).
post #56 of 90
Wanna sell it?wink.gif
post #57 of 90
"I still want to quantify how much SPL I'm giving up down low with the reduced excursion though."

the driver won't be moving much around the tuning frequency.

it will be moving max in the range from about 16-32hz given your setup.

assuming the sd of each driver is roughly the same, the advantage of the tumult can be found with the equation:

number of td15h's to equal one tumult = (xmax of tumult)^2 / (xmax of td15h)^2

34mm^2 / 23mm^2 = 1156mm/529mm = 2.19

so, in theory, the tumult is equal to 2.19 td15h's in the xmax limited region, or as bosso said, about a 2:1.
Edited by LTD02 - 10/13/12 at 2:30am
post #58 of 90
Quote:
Originally Posted by Ricci View Post

I don't really see anything wrong with the measurements of this system. Other than there are none from the listening position. This driver is probably a version 1 working just fine. The tummie exhibits about an 8dB roll off to 100Hz from a peak near 40-45Hz in a 100L sealed box. He shows a few DB more roll off but as I have mentioned earlier a close mic does just this so that is consistent with what you would expect. .

Interesting.

Do you have any examples of a close mic in free air showing a steeper roll off than the driver in a sealed box at GP? I haven't observed that to be the case... ever. Also, as I noted earlier, my close mic measurement of the Tumult in 100L shows the same roll off on the top end as Ilkka's GP and actually a more accurate roll off (2nd order) on the bottom than Ilkka's (10dB/octave).

In free air, the measurement should accurately reflect the Fs and the roll off at the top should be notably less than when in a sealed box, not more.

Also, he shows a heckuva lot more roll off in-box than a couple of dB. JJ's own measurements of the AV15H show a couple of dB drop at 100 Hz, but the OP's comparo shows a 12dB difference between box w/Tummie vs box w/AV15H when it should be 1/2 that at most.

To the OP, in your DATS exercise, you entered 13.75" for driver diameter. The Tumult is 12.2", according to Adire's published Sd and my measurement. That would change the result for the Vas and sensitivity calculations quite a bit, as far as modeling goes. Try the proper diameter input and use the result to try a new model.

IOW, it's impossible to make much of the posted data because it's not accurate. That means I disagree with Josh's assessment that there isn't anything wrong with the posted measurements of the system.

If you're not willing to whack together a 100L box (or use a larger one and displace the proper amount of interior volume to make it 100L) and measure close mic for a comparison against a known reference, which is the simplest way to get pointed in the right direction, then all that will happen here is a lot of useless speculation.

The posted data doesn't crunch. Regarding the model, it's incorrect T/S input. Regarding the measurements, is it the measurement rig, the driver, the box, the PRs, etc? No way to know from what's been posted, IMO.
post #59 of 90
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

the driver won't be moving much around the tuning frequency.
it will be moving max in the range from about 16-32hz given your setup.
assuming the sd of each driver is roughly the same, the advantage of the tumult can be found with the equation:
number of td15h's to equal one tumult = (xmax of tumult)^2 / (xmax of td15h)^2
34mm^2 / 23mm^2 = 1156mm/529mm = 2.19
so, in theory, the tumult is equal to 2.19 td15h's in the xmax limited region, or as bosso said, about a 2:1.
Where did you find that formula and what exactly are you deriving from it?

If we're comparing displacement the formula is Sd * xmax *2. In which case you get 749 * 3.4 * 2 vs. 794 * 2.3 *2 or 5.09L vs. 3.65L.
post #60 of 90
Thread Starter 
Quote:
Originally Posted by bossobass View Post

To the OP, in your DATS exercise, you entered 13.75" for driver diameter. The Tumult is 12.2", according to Adire's published Sd and my measurement. That would change the result for the Vas and sensitivity calculations quite a bit, as far as modeling goes. Try the proper diameter input and use the result to try a new model.
I'm not saying it's absolutely correct, but I followed the directions. I also noticed that their method isn't the 1/3rd of the surround number I'm seen mentioned elsewhere.
Quote:
Originally Posted by The Directions 
Each of the four methods of measuring V(as) requires that you enter the Piston Diameter of the driver. The piston diameter is the effective diameter of the acoustic piston formed by the speaker. The piston diameter is measured as the diameter of the speaker cone and normally includes about half of the surround on each side of the cone. For example, a nominal 8 inch woofer would probably have an actual piston diameter in the range from about 6.25 to 6.5 inches.
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