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Elite Shackster
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Discussion Starter #161
For an "apple" to "more apples" comparison, it should have been

The single driver sub has the SVC 15" version of the TC-2000 in a 90L (net) enclosure (front firing). A single ~2200W amp was used to power it (4 ohms bridged).

The dual driver sub has two SVC 15" versions of the TC-2000 in a 140L (net) enclosure (opposing firing). Two ~2200W amps were used to power it (both 4 ohms bridged).

I don't know how much of a difference it would make, but if you can use one of the SVC drivers in the single driver sub and the 2200W amplifier, that may have some answers.
Just a thought.
That is the same amp, 1800W vs. 2200W difference comes from the 4ohm/8ohm load. And maximum power doesn't affect the frequency response.

We will try my SVC driver in my friend's 90L cabinet. But I'm pretty sure 20L difference doesn't do much.
 

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That is the same amp, 1800W vs. 2200W difference comes from the 4ohm/8ohm load. And maximum power doesn't affect the frequency response.

We will try my SVC driver in my friend's 90L cabinet. But I'm pretty sure 20L difference doesn't do much.
I agree, but this would be worth a try.
 

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Here is some more info about the TC-2000 situation.

The single driver sub has the DVC 15" version of the TC-2000 in a 90L (net) enclosure (front firing). A single ~1800W amp was used to power it (8 ohms bridged).

The dual driver sub has two SVC 15" versions of the TC-2000 in a 140L (net) enclosure (opposing firing). Two ~2200W amps were used to power it (both 4 ohms bridged).

Both WinISD and Unibox suggest that the DVC version needs a little bit more volume for the same Qtc (around 90L vs. 70L for 0.7Q single driver). That means that both subs should have pretty much identical frequency responses.

Below are the frequency responses I measured last weekend.



As you can see, the single driver sub has much flatter response and the inductance peak is around 10 Hz lower. No model suggest that large difference between them. And actually the dual driver sub measures really close to the Unibox model. It's the single driver sub that's way off.
Hi Ilkka,

That single driver certainly isn't an on-spec TC-2000. A quick model suggests that the driver is most certainly much heavier, probably by ~100g, and likely has a much softer suspension. Who knows, maybe it's a 3000 coil on a 2000 frame. :scratchhead:

The smaller volume per driver would show some increase in distortion, but that seems higher than it should be, especially in relation to the other alledgedly similar driver. The numbers from the big vented TC-2k suggest a useful peak excursion around 28-30mm, where the lower frequency, dual driver limit is probably less than 1/2 that. How did the dual driver sub fair vs. the single in the sweeps at increasing output?

While I wouldn't expect it to make a big difference, did you happen to try driving both drivers from a single amp (maybe wired in series) to insure the drive from the amp wasn't contributing to the results? I somewhat doubt it as the output up high would likely have been affected.

The simple conclusion is that something is certainly off spec on the single driver sub (in a good way in this case) and something could also be off with your pair of drivers. If possible, the next thing to do is to take some in-box and free air impedance measurements of the drivers to see the differences. I do think it's imporant for readers to remember that exceedingly few DIYers do any in-depth confirmation of the system's performance, so most would never identify these issues.
 

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Hi Ilkka,
......The simple conclusion is that something is certainly off spec on the single driver sub (in a good way in this case) and something could also be off with your pair of drivers. If possible, the next thing to do is to take some in-box and free air impedance measurements of the drivers to see the differences. I do think it's imporant for readers to remember that exceedingly few DIYers do any in-depth confirmation of the system's performance, so most would never identify these issues.
This is exactly the reason why I want to learn how Ilkka does these measurements. Maybe sometimes ignorance is bliss, but unless you measure, how would you know.
 

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Elite Shackster
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Discussion Starter #165
Hi Ilkka,

That single driver certainly isn't an on-spec TC-2000. A quick model suggests that the driver is most certainly much heavier, probably by ~100g, and likely has a much softer suspension. Who knows, maybe it's a 3000 coil on a 2000 frame. :scratchhead:
Thanks Mark. Could it also be less flow in the gap? That would cause higher Qts which would make the frequency response extend lower.

The motor that came with the driver was demagnetized (or never was magnetized). TC swapped it so I know the coil isn't at least a 3000 coil. Here's a picture of it.



The smaller volume per driver would show some increase in distortion, but that seems higher than it should be, especially in relation to the other alledgedly similar driver.
At the same output level the dual driver sub should still be ahead in distortion limited output even with slightly less volume per driver.

The numbers from the big vented TC-2k suggest a useful peak excursion around 28-30mm, where the lower frequency, dual driver limit is probably less than 1/2 that. How did the dual driver sub fair vs. the single in the sweeps at increasing output?
I wasn't able to push them into full compression at low frequencies since I wasn't using any EQ. Amps clipped already up higher. The maximum level that I recorded at 20 Hz was 102 dB for the single driver subs and 106 dB for the dual driver sub. AA Tumult did 101 dB.

While I wouldn't expect it to make a big difference, did you happen to try driving both drivers from a single amp (maybe wired in series) to insure the drive from the amp wasn't contributing to the results? I somewhat doubt it as the output up high would likely have been affected.
I checked that (with a DMM) both amps did output the same voltage, but that's all. At home I've been using a single amp (both in series and parallel). I doubt that was the problem.

The simple conclusion is that something is certainly off spec on the single driver sub (in a good way in this case) and something could also be off with your pair of drivers. If possible, the next thing to do is to take some in-box and free air impedance measurements of the drivers to see the differences. I do think it's imporant for readers to remember that exceedingly few DIYers do any in-depth confirmation of the system's performance, so most would never identify these issues.
I have already taken an in-box impedance measurement for my dual driver sub. I will take the rest when I visit my friend.
 

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If this type of testing (which we all know is very rare to find) reveals a difference between the SVC and DVC drivers (if there is indeed one) and we may end up learning that there is a difference between the two. At least as of now that's what the data appears to allude.

This begs the question, how much difference is there indeed between a TC2K, a TC3K and an LMS 5400 in real life. Models use parameters and one issue is that the parameters maybe off and a model is no substitute to real world measurements. All that we can do is hope that the parameters are right and that the model is as close to real world.

Ilkka, is there a possibility of you measuring an LMS 5400 anytime soon?
Being their flagship product, this would be something very useful to me and a lot of other folks reading this. According to my knowledge and based on inputs, there is no other driver in the USA that is available to DIYers, that matches or beats the LMS 5400 in that price range.

But this driver has not seen a ruler like yours. So it still remains just a claim only backed up by specs and a few DIYers who have tried it and are happy but have not done extensive measurements like yours. :waiting:
 

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Elite Shackster
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Discussion Starter #167
Ilkka, is there a possibility of you measuring an LMS 5400 anytime soon?
Being their flagship product, this would be something very useful to me and a lot of other folks reading this. According to my knowledge and based on inputs, there is no other driver in the USA that is available to DIYers, that matches or beats the LMS 5400 in that price range.
I originally wanted to use the LMS-4100 NEO drivers in my dual driver sub, but since they were delayed so many times, I decided to try the TC-2000's first.

The LMS-5400 is a little bit too expensive for me to buy just for a test. If TC-Sounds wants to send me one, I'd be happy test it.
 

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Thanks Mark. Could it also be less flow in the gap? That would cause higher Qts which would make the frequency response extend lower.

The motor that came with the driver was demagnetized (or never was magnetized). TC swapped it so I know the coil isn't at least a 3000 coil. Here's a picture of it.
If the motor never made it to the magnetizer, who knows what else was wrong. It's somewhat possible that low BL, combined with a much softer suspension could give the response you measured, but tough to say without seeing a comparison of the impedance curves. Which of the drivers you and your friend have had to have the motor replaced? Just his in the 90L box?

I wasn't able to push them into full compression at low frequencies since I wasn't using any EQ. Amps clipped already up higher. The maximum level that I recorded at 20 Hz was 102 dB for the single driver subs and 106 dB for the dual driver sub. AA Tumult did 101 dB.
Maximum output from a swept sine seems reasonable given the available power, response curves, and assuming some compression at those levels. BTW, was the Tumult driven with the same amp as the TC-2000 subs? There are a few reasons for excessive 2nd order distortion, and testing one or both of your drivers in the 90L box would give a more direct indication.
 

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Elite Shackster
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Discussion Starter #169
If the motor never made it to the magnetizer, who knows what else was wrong. It's somewhat possible that low BL, combined with a much softer suspension could give the response you measured, but tough to say without seeing a comparison of the impedance curves. Which of the drivers you and your friend have had to have the motor replaced? Just his in the 90L box?
Yes, just his. I have measured that my drivers are pretty much identical compared to each other.

Maximum output from a swept sine seems reasonable given the available power, response curves, and assuming some compression at those levels. BTW, was the Tumult driven with the same amp as the TC-2000 subs? There are a few reasons for excessive 2nd order distortion, and testing one or both of your drivers in the 90L box would give a more direct indication.
The Tumult was driven with a Yamaha M-85 stereo amplifier. It's very old but pretty powerful amp. The Tumult has 2x2 ohm coils, so I'm guessing around 2x600W RMS.
 

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I'll come out of hiding for a few random comments.

When posted, this latest round of testing will only serve to yet again confirm why Ilkka is the absolute best resource we subwoofer enthusiasts have. He contributes significantly more to this area of interest than anyone, bar none. It's not just these subwoofer shootouts either, when a topic of debate comes up, like electronics rolloff, DRC, dissimilar results from two other parties, or group delay in port use, he's kind enough to take some measurements to prove things one way or the other. And many times he does it while taking grief from some of the jokers that like to frequent some of the other forums as well. So to start, big thumbs up to Ilkka :T

Next, reading through this thread, the XYZ company trying to boast about high frequency output from their product is kind of funny, as the DIY subs show that a legitimate subwoofer can best that product and stay pretty linear into the teens as well, thus making it seem rather useless. But I don't want to get sidetracked so soon, I'm only just starting :R

Though not much data has been posted yet, I can't imagine the LLT performing poorly, it will probably do very well....likely the best single driver sub and best performer per dollar tested by a wide margin. That said, the design isn't exactly optimized for the driver in my opinion. Had a larger enclosure with a lower tune been used, I believe the results would be even more impressive in terms of low end output and the onset of port compression. An ideal LLT would be able to effectively use a large enough port to all but eliminate compression, but that's a little difficult to pull off with the TC2000 and RL-p15. No big deal though.

It will be interesting to see if my stance on amp limiting LLTs wasn't really even necessary, perhaps even detrimental to max performance. It would be a simple fix for owners in terms of bridging an amp or buying a second, but this is the topic I am probably looking forward to most.

Distortion limited output of sealed 15" drivers with low end boosting will be very informative me thinks :devil:

I also believe this round of testing will go to show that simulations are more accurate than some like to give them credit for. Based on the direct comparison of a sealed TC 2000 and a LLT version, extrapolations in other circumstances will gain a lot more legitimacy.

As for the comments on the LMS 18" being the best driver out there, I'd put the XXX 18" with xbl^2 and 54mm xmax above it.

I'd have to think this type of testing with some quality diy subs won't exactly make some companies very happy :bigsmile: You'll always have a group who isn't interested in building anything, but more and more people have been making the switch to diy, and I'd have to think this would push over another nice big chunk who were sitting on the edge.

Anyway, thanks again for all the work Ilkka, can't wait to see the full spectrum of data.
 

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I popped by the finnish subwoofer forum the other day, and even though I don't understand more than a couple of words in finnish I got a good laugh from a post with picture comparision





:neener: :jump:
I was the one to make up that pic of the "twins" :R :rofl2: Just couldn't help noticing the resemblence. But those endcaps are actually pretty ingenious, I'm a bit tired of vertical, all-black sonos..

Hope you get the driver issue sorted out, sounds like something is off with the single driver, which actually seems positive in this case, if one looks at the FR graph. Mark has made some good guessed about what could be wrong, I second those.


Too many smilies here at HTS to choose from :coocoo:
 

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If the end user will be using EQ to flatten in room response of a sealed sub, the differences in the natural FR of the TC 2000 driver won't really matter too much, as output at a given frequency will still be based on excursion. The distortion differences should be negligible at best. With distortion being a good indicator of excursion in a sealed sub, we can extrapolate all we need to make comparisons - hopefully Ilkka will post all the data and not wait on a resolution from TC Sounds (cough..hint, wink).
 

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So why you are thinking that max SPL was off? Is it too high or low?
No I haven't been following close enough as the conversation transpires. You summed things up in this post and what is contained beyond.

As you can see, the single driver sub has much flatter response and the inductance peak is around 10 Hz lower. No model suggest that large difference between them. And actually the dual driver sub measures really close to the Unibox model. It's the single driver sub that's way off.

When we look at the distortion limited output numbers, the single driver subs kills the dual sub below 40 Hz, as the frequency response indicates.

Below is the updated spreadsheet.
I'd have to think this type of testing with some quality diy subs won't exactly make some companies very happy You'll always have a group who isn't interested in building anything, but more and more people have been making the switch to diy, and I'd have to think this would push over another nice big chunk who were sitting on the edge.
Hey Steve is that you? Well please! dont you forget how easily the LLT bottoms:whistling: Good to see ya Steve.
 

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steve nn said:
Hey Steve is that you? Well please! dont you forget how easily the LLT bottoms Good to see ya Steve.
Oh yeah, almost forgot a couple more random thoughts. Without trying to stir the pot too much, seeing as the TC 2000 and RL-p15 are VERY similar drivers, this testing should reveal a half hearted attempt at diy to be what most of us knew it was going to be.

Also, the exact design of this LLT being tested is what your old buddy Steve nn almost made available to US customers for $1000 shipped to your door as a very sexy black on black sonosub. Things unfortunately didn't work out, but when you look at what commercial manufacturers are offering for $1000 (including shipping), and then see what this thing can do, Steve would have been a very popular guy me thinks :yes:

Good to see you too!
 

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Elite Shackster
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Discussion Starter #177
The distortion differences should be negligible at best. With distortion being a good indicator of excursion in a sealed sub, we can extrapolate all we need to make comparisons - hopefully Ilkka will post all the data and not wait on a resolution from TC Sounds (cough..hint, wink).
I just plotted some distortion sweeps. Some really interesting info there... :nerd:
 

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Elite Shackster
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Discussion Starter #178
Well please! dont you forget how easily the LLT bottoms:whistling: Good to see ya Steve.
Well actually we did bottom out the LLT while taking the compression sweeps... That happened around 30 Hz and 113 dB level (RMS).

edit: Further research showed that it didn't bottom. It was the amp that clipped.
 

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Well actually we did bottom out the LLT while taking the compression sweeps... That happened around 30 Hz and 113 dB level (RMS).
Yeah but if memory serves me correct, you had a couple K?? of juice flowing didn't you?
 

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Interesting - I seem to recall telling that certain someone that the bottoming they were experiencing was coming from above tuning, not below. The way they wired the driver and the amount of power they supplied it would cause it to bottom above tuning when playing the same WotW scene over and over and increasing the volume.
 
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