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

**Blaser** · **06-18-07, 04:32 PM**

Quote:

Sonnie wrote:

I apologize for not realizing this thread is in the wrong forum earlier than now, but it should indeed be in the SoundSplinter forum. It is officially moved.

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

OK for this time but don't do it again

**SteveCallas** · **06-18-07, 04:44 PM**

Quote:

blaser wrote:

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.

Quote:

blaser wrote:

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

**Ilkka** · **06-18-07, 04:49 PM**

Quote:

SteveCallas wrote:

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

What drawbacks, Steve?

**SteveCallas** · **06-18-07, 05:12 PM**

The potential to bottom the driver, wear out the spider's bond to the frame, or fry the voice coil.

**Scott S** · **06-18-07, 05:33 PM**

As long as one is smart with the volume control he shouldn't be tearing anything.

**Blaser** · **06-18-07, 05:36 PM**

Quote:

SteveCallas wrote:

But have you ever heard of a speaker bottoming out? Commercial speakers will often use a highpass in the crossover for added protection.

I was addressing the voice coil heating issue here

Quote:

Actually, the driver would have to use more excursion, not less.

You are assuming the amp can deliver its rated power everywhere at the same time but that will not happen

Quote:

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

OK, but I don't need to wait for Ilkka's results...you'll see

**Blaser** · **06-18-07, 05:42 PM**

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

so maybe they need less power and a high pass.... but my amp couldn't bottom the drivers on the very deepest scenes.

**Ilkka** · **06-18-07, 05:43 PM**

Quote:

SteveCallas wrote:

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.

Quote:

wear out the spider's bond to the frame

Proper drivers shouldn't have any problems with this one.

Quote:

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.

**SteveCallas** · **06-18-07, 06:10 PM**

Quote:

Ilkka wrote:

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

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

that's pretty extreme.

Quote:

Ilkka wrote:

Also huge amps are for smart users

I guess I'll need to stick to the Dayton 70w plate amp then

Quote:

Ilkka wrote:

Proper drivers shouldn't have any problems with this one.

They shouldn't have any problems with the surround detaching from the cone either

Quote:

Ilkka wrote:

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.

**Blaser** · **06-18-07, 06:17 PM**

" They shouldn't have any problems with the surround detaching from the cone either "

That's a good one

Ilkka pls take it easy

**Ilkka** · **06-18-07, 06:29 PM**

Quote:

SteveCallas wrote:

Errmm, my own arguments being used against me

Who was the one who actually measured the electronics roll-off?

Quote:

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.

Quote:

Blaser is talking about pushing a single driver to 125db levels though

that's pretty extreme.

Are you underestimating the "LLT" now?

If it can take it, what's the problem?

Quote:

They shouldn't have any problems with the surround detaching from the cone either

I somehow guessed you would bring that up.

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.

Quote:

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?

A bridged EP2500 can not "toast" a RL-p nor TC-2000 when using pure program material and not clipping the amp.

**Blaser** · **06-18-07, 06:30 PM**

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

**Blaser** · **06-18-07, 06:37 PM**

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!

**Scott S** · **06-18-07, 06:51 PM**

Lift-off on construction of my dual 'LLT' RL-p18's is commencing this or next week...

Gotta love these SPL reading from just one RL-p! Can't wait to shake the out of this side of the house!

Blaser - Is your LP at or close to a wall/backwall? Just curious... I haven't seen any pics of your LP yet.

**Blaser** · **06-18-07, 06:56 PM**

Hi Scott,

My LP is close to the back wall while my subs are along the front walls. about 4 m from LP, behind speakers and TV.

You will be amazed with your subs....how big is your room? I would gladly give you some construction hints if you need...

**Scott S** · **06-18-07, 07:05 PM**

Oh! I was curious because I will be putting my dual RLp18's in a room about as small as yours. I may have a higher ceiling, idk. My LP is about 4-5ft from the backwall but the backwall is actually the sliding doors for the in-room closet. I call it the "fourth bedroom" because....well, it was supposed to be a guest room. When we moved in, I told my dad I needed a dedicated room for my HT and we never have guests. Lolz.

The rough measurements for my room are about 20ft x 10-11ft x 9ft. The thing is...my room is pretty rectangular but the front of the room is about a foot wider than the rest of the room. And I wasn't sure if the closet was supposed to be accounted for.

I can link some pics of my HT if anyone is interested.

**Blaser** · **06-18-07, 07:18 PM**

Sure.... with my very small experience, room acoustics are very hard to predict, but your one might be better than a fully rectangilar one...

FYI, I have some room cancellation at 11-15 Hz compared to door open...It is weird, but that's the case.

**Scott S** · **06-18-07, 07:25 PM**

That is something I haven't taken too seriously...

Measuring the FR with the door open or not. I prefer to have it shut as to not disturb the rest of the house. The main reason I put my HT on the farthest end of the house.

Haven't used REW yet but I may soon. Just gotta get a couple of cables and another LCD screen to take into my HT. Or maybe a decommissioned laptop...

**WillyD** · **06-18-07, 08:45 PM**

Quote:

A bridged EP2500 can not "toast" a RL-p nor TC-2000 when using pure program material and not clipping the amp.

No kidding. I don't know why Steve always brings up VCs being "toasted" w.r.t TC/SS drivers.

**F1 fan** · **06-18-07, 10:17 PM**

Quote:

SteveCallas wrote:

Commercial speakers will often use a highpass in the crossover for added protection.

Highly unlikely,unless it was the designers original intent that the speaker be used in a system with a matching subwoofer.Otherwise they would want to maximise bass extention as much as possible even in small 2 way systems.Speaker companies assume that most HT users will use some sort of bass mgmt/HP function in their AVR or Pre/ Pro to do the job.The 2 ch guys that don't use subs will not want the bass rolled off prematurely.

**Blaser** · **06-20-07, 01:05 PM**

I have disassembled the subs and they were sent downstairs for priming and painting....This very sad I have to wait 3-4 days without the subs

**SteveCallas** · **06-20-07, 01:39 PM**

Quote:

Ilkka wrote:

Are you underestimating the "LLT" now? If it can take it, what's the problem?

Fine, fine, I will cease and desist.

Quote:

Ilkka wrote:

I somehow guessed you would bring that up. 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.

I didn't mean to say it was because of the power run through it, I was just poking fun at your statement that a "proper" driver wouldn't have any issue with the spider wearing out - a "proper" driver wouldn't have any issue with the surround coming off either. It was more a jab at TC Sounds than anything else

**Blaser** · **06-20-07, 01:58 PM**

Yes, Ilkka was unlucky...

**Scott S** · **06-21-07, 07:20 PM**

Quote:

....This very sad I have to wait 3-4 days without the subs

Agh! Tell me about it...this isn't even my project and I want them done, already.

**Blaser** · **06-22-07, 05:06 PM**

Thanks!! Tomorrow, it will end

Advertisement