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Dual RL-P18 LLT for my 2000 cu ft HT soon

31K views 182 replies 19 participants last post by  Blaser 
#1 ·
Final design not completed yet, but I will go for 2 boxes 550-600 L effective, 16 Hz tune, 8" or 10" port, powered by EP 2500, dual 2 ohm configuration.

I am not that good in woodworking, so I am only making the design on paper, but will have the job performed by a carpenter.

I have some variables I would like your advice about:

- MDF or not? If MDF, 16mm, 18mm, or 22 mm? Front baffle will bear both the driver and port.
- Is bracing a must? Never read that anybody made an enclosure without bracing, but I did that for my 4cu ft car sub. and it is rock solid and working very very well, I can even stand on it... no problem. Of course at least the port will be internally supported.
- Insulation: Is it a must? If yes, is 1" fiberglass ok? Should the volume be taken into consideration? I never read someone did...

Your inputs are highly appreciated.

Blaser
 
#105 · (Edited)
LOL...so what explains the louder perception of the new subs when hitting the same SPL as the old sub.

Btw, I hit 126 db uncorrected yesterday, and I was not at max volume (but there was some compression though) :cunning: :devil: But it was much more scary than the feel I have in my car. Still weird...Is this the impact of very low frequencies?
 
#106 ·
Some more pics
 

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#112 ·
One thing about the price of this amp: I had 20% discount as VAT is not applicable in my country....but I paid other local taxes.
 
#113 · (Edited)
Hi all,

I need your help in analysing what's happening at listening position. I am open to suggestions....Pls advise!
 

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#114 · (Edited)
Here are the graphs with mains.
 

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#115 · (Edited)
:cool: Update: All of my neighbours were out today, and it was an opportunity to test the drivers/amp:devil: for those who like Deep bass and would like to have an idea about the SPL performance of the RL-P18.

All tests were performed at listening pos at 4m from subs...5 second tests not more.

WOTW pode emerging scene:
Dual woofers: 126 db uncorrected RS SPL meter, amp clipped.
Single Woofer: 122 db amp clipped.

WOTW Laser Scene
SINGLE WOOFER:
125 db:raped:, amp clipped
I didn't dare to play this scene that high with dual woofers....but It would have been close to 128-129 db.

This is a car bass performance with much deeper bass:innocent:

I think I need another amp:coocoo::rofl2::rofl: and maybe soundproof my room:heehee:
 
#118 ·
I will buy in the future another amp to be able to use the full capability of the subwoofers (just as an option)....as I find the price of the amp very cheep, and very performant. (If you ride a Ferrari, you do not have to go 200 miles an hour, but it is good to have the capability)

FYI, bass is not as hard to bear as mids and highs....I can probably enjoy 130db from 25 to 45 Hz...but cannot stand 110 db at say 1 Khz.

The sound of unstressed subs is very pleasant, and I beleive that one can never have enough headroom.The feeling of having limitless headroom is very very pleasant!!

Another update for you guys on M&C....The subs clipped the amp at the canon opening scene at 126 db SPL (RS reading)....But I did feel the cannons, I'm lucky my building is concrete:bigsmile:

The drivers did not seem overstressed nor unable to comply, nor bottomed out with any program material without high pass....:nono:....Only the amp clipping sound was noted.

For those who really think they can bottom out an LLT at moderate or even at extreme levels :rolleyes::rolleyes::rolleyes::rolleyes::rolleyes:.... I tell them that I have been playing M&C, and WOTW (2000W into a single RL-p18, 125 db at LP) and never bottomed out the sub.

If you have the space or can have it placed efficiently in room, go for an LLT....It is the very best/powerful/deepest subwoofer configuration I have ever heard:T.
 
#119 ·
The drivers did not seem overstressed nor unable to comply, nor bottomed out with any program material without high pass....:nono:....Only the amp clipping sound was noted.

For those who really think they can bottom out an LLT at moderate or even at extreme levels :rolleyes::rolleyes::rolleyes::rolleyes::rolleyes:.... I tell them that I have been playing M&C, and WOTW (2000W into a single RL-p18, 125 db at LP) and never bottomed out the sub.
I can think of at least one person who might think differently. :rolleyes: :rofl:
 
#120 · (Edited)
I would caution trying to "go for broke". You may not notice any sounds besides the amp clipping, but that doesn't necessarily mean you aren't stressing the driver pretty hard beyond its xmax. I believe the xmech is in the 40mm range, so physical damage may not be a concern, but what do you really gain by adding another 2000 watt amp except maybe the capability to bottom the drivers in the 20-30hz range or fry the coil?

When Ilkka mentioned that the TC2000 was able to handle up to 2000 watts, I initially thought I may have been off the mark with my amp limiting practice. However, after thinking about it more, the best one can hope to achieve by doubling the power is only 3db, and that's assuming no compression. I'm pretty sure his measurements will show some compression from the highest output level to the second highest, especially down low with the 6" port. In return, he found that he was able to get the driver to bottom between 20-30hz. When I weigh that potential benefit (3db under ideal circumstances) vs the drawback (the potential to damage a driver), I don't see any reason to go for it. I'd take your amp clipping as a red light.

As for that other fellow who thinks he was bottoming with low frequency material - and that his highpass saved the day - his intentions were never good willed to begin with. The whole thing was transparent from day one. If you will recall, he actually ranked several commercial 12" subs as being much more articulate than his frankensub :rolleyes: That shouldn't be a shock though seeing as his other tests have shown his strong preference for distortion.
 
#121 ·
I'm pretty sure his measurements will show some compression from the highest output level to the second highest, especially down low with the 6" port.
"Some" is such a vague term, but I can tell you that it didn't show "much" compression. ;)

In return, he found that he was able to get the driver to bottom between 20-30hz.
This is what I initially thought, but after some careful research, I'm almost 100% certain that it was the amp clipping instead.

Two reasons:

1) TC-Sounds have told me that it is pretty much impossible to mechanically bottom a TC-2000 with an older half-roll upper surround. It simply can not support >40mm one-way excursion without breaking up. The new high-roll surround is a different case. The one I tested had the older upper surround.

2) Heavy amp clipping can sound almost exactly like mechanical bottoming. It can easily fool you - even me. :duh:


I think Blaser's subwoofers are just fine with two 2000W amps. :)
 
#126 ·
Why Sonnie, I am not only using SS drivers, but there is also wood, the T-amp, wiring, binding posts...painting soon, not all of them are SS:bigsmile::innocent:

OK for this time but don't do it again:R:R:R
 
#123 ·
Ilkka said:
"Some" is such a vague term, but I can tell you that it didn't show "much" compression.
So would you classify it as a "bit" of compression? :bigsmile:

I know you are still compiling all the data, but any way you could let the TC 2000 LLT output compression graph slip out under the radar (either onto this thread or in my PM box)? :wave:
 
#125 ·
Hi Steve,

Glad to see you post here:). Thankfully you did not misunderstand my post(about bottoming the driver), I meant below tuning and not above :devil:!! I do believe that your theory of subwoofer amp limiting is very good specially for beginners, but I think as well that similations only tell you the story if you were to work with a single frequency at a time, but not on real program material where multi-frequencies are to be reproduced simultaneously.

Yes if I used a sin wave at 20 Hz, the sub. would propably bottom, but on real material, it never happened. Don't misunderstand, I do respect what you say, but I think while similations are single frequency based, real material having multi frequencies to reproduce will use the amp power and "distribute it over these frequencies" with the woofer having less excursion overall!!

From the other side, it is very common that many manufacturers recommend to use twice to 4 times the speaker RMS power, why? because if 2000 W for ex. is to give you 10 db peaks, you will still be running at 200 W RMS. I think we can never have enough headroom for subs.

Last, if I ever add another amp. It won't be to add any SPL for my system, but to have a bit more headroom for short peaks.... But this will not be to improve the reading to be 130 db or so. It seems contradictory but that's it. The other reason to do so is that I want to stress the amps a bit less as I might disable the noisy fans (but that's another story).

Again, thanks for having helped me in my design specially the choice of the tune:hail: you were right!!
 
#127 ·
blaser said:
From the other side, it is very common that many manufacturers recommend to use twice to 4 times the speaker RMS power, why? because if 2000 W for ex. is to give you 10 db peaks, you will still be running at 200 W RMS. I think we can never have enough headroom for subs.
But have you ever heard of a speaker bottoming out? Commercial speakers will often use a highpass in the crossover for added protection.

blaser said:
Yes if I used a sin wave at 20 Hz, the sub. would propably bottom, but on real material, it never happened. Don't misunderstand, I do respect what you say, but I think while similations are single frequency based, real material having multi frequencies to reproduce will use the amp power and "distribute it over these frequencies" with the woofer having less excursion overall!!
Actually, the driver would have to use more excursion, not less.


I guess I will reserve further comment until I see Ilkka's data, but I just don't see the potential benefit outweighing the potential drawbacks :dontknow:
 
#133 ·
The potential to bottom the driver
That's the only downside. Although I wouldn't call it a huge risk with these 80 mm peak-to-peak drivers. Especially with program material, and when considering the electronics roll-off. Also huge amps are for smart users. ;)

wear out the spider's bond to the frame
Proper drivers shouldn't have any problems with this one.

or fry the voice coil.
Actually it's more easy to fry the voice coil with a lesser amp. That's because when the amp clips, the average energy/power of the waveform goes higher. A clean signal has always less energy at the same level.
 
#132 · (Edited)
Steve,

According to my torture tests....What I think is that even with a 2000 W amp, the driver is still amp protected on program material.

Some other guys say to have bottomed their LLT at 4 Hz:bigsmile: so maybe they need less power and a high pass.... but my amp couldn't bottom the drivers on the very deepest scenes.
 
#134 ·
Ilkka said:
Although I wouldn't call it a huge risk with these 80 mm peak-to-peak drivers. Especially with program material, and when considering the electronics roll-off.
Errmm, my own arguments being used against me :R In all seriousness though, the potential problem area with LLTs and too much power would be the 20-30hz range, as the rolloff would protect the low end. This is assuming one plays at extreme output levels, which 95% do not. Blaser is talking about pushing a single driver to 125db levels though :scared: that's pretty extreme.

Ilkka said:
Also huge amps are for smart users
I guess I'll need to stick to the Dayton 70w plate amp then :bigsmile:

Ilkka said:
Proper drivers shouldn't have any problems with this one.
They shouldn't have any problems with the surround detaching from the cone either :whistling:

Ilkka said:
Actually it's more easy to fry the voice coil with a lesser amp. That's because when the amp clips, the average energy/power of the waveform goes higher. A clean signal has always less energy at the same level.
I guess, but I vividly recall helping chasw with his first LLT design using a 15" DVC and completely toasting it with a bridged EP2500. He's clipped the amp on the RL-p15 many times with no heat issues. Now obviously these are two different drivers with two different coils, but I haven't heard of any frying being caused by clipping, unless one pushes on through clipping without turning down the volume. Not saying it hasn't happaned though.
 
#136 ·
Errmm, my own arguments being used against me :R
Who was the one who actually measured the electronics roll-off? ;)

In all seriousness though, the potential problem area with LLTs and too much power would be the 20-30hz range, as the rolloff would protect the low end. This is assuming one plays at extreme output levels, which 95% do not.
Yes, that range would most probably cause the bottoming, but I don't see it being a huge risk with these 80 mm p-p excursion drivers, even with 2000 watts. Now something like 10 kW would be a different case.

Blaser is talking about pushing a single driver to 125db levels though :scared: that's pretty extreme.
Are you underestimating the "LLT" now? :R If it can take it, what's the problem?

They shouldn't have any problems with the surround detaching from the cone either :whistling:
I somehow guessed you would bring that up. :sarcastic: Would it have prevented it, if I had used only a 500W amp? Remember that the surround detached during a 95 dB sweep.

It was a manufacturing error instead (too little glue). Nothing to do with the amp power I was using.

I have fixed it now and I clipped the same 2000W amp in free-air while testing it - no detaching surrounds anymore. :bigsmile:

I guess, but I vividly recall helping chasw with his first LLT design using a 15" DVC and completely toasting it with a bridged EP2500. He's clipped the amp on the RL-p15 many times with no heat issues. Now obviously these are two different drivers with two different coils, but I haven't heard of any frying being caused by clipping, unless one pushes on through clipping without turning down the volume. Not saying it hasn't happaned though.
15" DVC? Is that the Dayton driver? Are you seriously comparing it to the RL-p? :eek:

A bridged EP2500 can not "toast" a RL-p nor TC-2000 when using pure program material and not clipping the amp.
 
#135 ·
" They shouldn't have any problems with the surround detaching from the cone either "

That's a good one:bigsmile::joke::rofl: Ilkka pls take it easy:kiss:
 
#137 ·
I have arranged to have the boxes primed and spray painted within 2 days....more pics will come then,

And maybe this will be an opportunity to have a pic inside the sub...We'll see if this is doable:bigsmile:
 
#138 ·
By the way, I have pushed a single driver to 125 db in a 5 sec. test only (because I promissed Stevenn to inform what it is capable of in my room), but I don't do it as a habbit....my listening habbit is around 112-115 db both drivers working...I cannot risk to spoil them and I don't need 125 db to enjoy them either.

Don't forget I have neighbours!
 
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