So curious after last night...

[audibleconnoisseur]

How many of you out there have played a CMT340SE loud enough that you blew it? If you have not blown it, how many of you have actually tested the SPL's @ or around 1m and what was the highest level you were willing to let it go? What receiver (what W/ch) were you pushing it with?

I know they will play louder, but I had mine at around 110dB @ 1m last night :eek: and I figure that was about 64W peak, according to quick math of 92dB @ 1m sensitivity. Since I only have a rated 80/ch, I figured I should not attempt higher for fear of clipping and not having the power necessary to drive them more as it would have needed about 128W to push it to 113dB if I am correct?!

[BradJudy]

How do you figure it was peaking at 64W? In a demo at the RMAF, it was shown that peaks were about 10x the average power consumption. During playback that was moderately loud, but not too loud, the average power output was 20-30W and the peaks were 200-300W!

[audibleconnoisseur]

As stated prior, I am no speaker professional! I was using something Dave said where if you start at the speakers sensitivity of 92dB @ 1m @ 1W, it usually takes doubling the power to have a 3dB increase, so

92 @ 1
95 @ 2
98 @ 4.....
110 @ 64

I am not sure that this was the case, but was using that as assumption. I would like to know EXACTLY what watts my D1905 is pushing through at any given time. Short of a volt meter at the back of the receiver or the input of the speaker, how can I tell? I want to know for certain what I CAN and CAN'T do with them. Would you be willing to offer help? If I was only pushing 20W @ that level then in NO way will I further consider the upgrading of my receiver!

[Gov]

I seriously think your ears would start to bleed before the 340's would blow up with your Denon receiver. I could be wrong tho :cool:

[GirgleMirt]

Quickly, I believe the specs on the 340SE page indicate max peak 400 watts and max continuous 240 watts. I think higher than that the voice coils will just melt, or/and catch on fire...

Knowing that, you can work up the math for max dB like you did with the sensitivity rating.

Thing is you have a more chances of damaging the speaker with an underpowered amp than an overpowered amp. The underpowered amp will start to clip before getting to the max 340SE power ratings, and then you risk damaging the tweeter, but you'll hear distortion from it so its easy to turn it down a little until the amp doesn't clip.

Heh i got curious... I think they're around 90dB, so 400 watts would give you like 117dB @ 1 meter

80dB = vacuum cleaner
98dB = large orchestra
100dB = Jackhammer at 2 m (7 ft); inside discothèque, walkman max lvl
110dB = Front row at Rock concert; chainsaw @ 1m
120dB = car horn @ 3ft, Jet takeoff (200 ft)
130dB = Thunderclap, threshold of pain

So more than enough to permanently ruin your hearing :D

[azanon]

How many of you out there have played a CMT340SE loud enough that you blew it?

Per what the last guy suggested, how many of us actually have a receiver/amp that we could damage this speaker by playing it too loud? I'm guessing a very small fraction, if that. How many here do we have that could damage it by clipping though? Probably several of us.

I will say this; i have turned my AVR 140 to as high as it would go (running my VTF-2 handling the bass), and I noticed 2 things; 1. It was really hurting my ears. 2. I didn't detect even a hint of clipping. 2 days later, my right ear still feels like its plugged a bit (which means i probably damaged it a little bit).

So it makes me think H/K basically designs their receivers in such a way thats its impossible to overload them (at least while running a sub for the lows). Also note though i'm not running the back center channel so the full availability of wattage isnt being used.

[BradJudy]

Your math is accurate for averages. The extremely brief peaks were likely in the hundreds of watts (i.e. your amp was clipping). It's a bit of a myth that all amp clipping is obviously audible - severe clipping is clearly audible and potentially harmful to speakers, but the RMAF demo and discussion clearly showed that clipping is far more common than generally understood, but also not as awful as generally thought. It definitely prevents sound from being correctly reproduced, but only having 150W to back a 200W is a different game than not being able to keep up with the average power demands.

Not to mention that the rated average power output of an amp might not be the same as the peak power output (depending on how the amp was tested/rated - AV receiver ratings are often shown to not be accurate average ratings).

[curtis]

As stated prior, I am no speaker professional! I was using something Dave said where if you start at the speakers sensitivity of 92dB @ 1m @ 1W, it usually takes doubling the power to have a 3dB increase, so

92 @ 1
95 @ 2
98 @ 4.....
110 @ 64

Those numbers are for ONE speaker.

[kinggimp82]

im just curious what clipping sounds like. basically just distortion? would clipping be a small threat if running 170 x-overed @ 100 hz?

[audibleconnoisseur]

Why would you want to cross your 170's over with your sub @ 100Hz?

[azanon]

Those numbers are for ONE speaker.

Two or 3 speakers played at the same decibel level is only slightly louder than one speaker played at that level. Certainly dont suggest its additive or even anything close to that.

[Sam1000]

im just curious what clipping sounds like. basically just distortion? would clipping be a small threat if running 170 x-overed @ 100 hz?

I think it would be a small threat since most of the hard work will be done by the sub in that case..

[audibleconnoisseur]

but the point is that if there is a crossover @ 60 or 80Hz... NOTHING should pass through below this point to the speakers. that is why it is there. i would be pretty pissed if they messed up b/c the receiver didn't catch the lfe below the crossover. anyone else have any thoughts? or, have any of you been able to hear your volume increase or decrease through your sub or speakers if you hold the volume know down or up?

[curtis]

but the point is that if there is a crossover @ 60 or 80Hz... NOTHING should pass through below this point to the speakers. that is why it is there. i would be pretty pissed if they messed up b/c the receiver didn't catch the lfe below the crossover. anyone else have any thoughts? or, have any of you been able to hear your volume increase or decrease through your sub or speakers if you hold the volume know down or up?
The crossover is not a brinkwall filter.....so if you cross at 60hz or 80hz, depending on the crossover slope and volume level, the speakers will still get some information as low as 30hz...or lower.

[audibleconnoisseur]

Anything that can/will hurt them if they are up LOUD?

[curtis]

Very doubtful.

[GirgleMirt]

The crossover is not a brinkwall filter.....so if you cross at 60hz or 80hz, depending on the crossover slope and volume level, the speakers will still get some information as low as 30hz...or lower.
What is a brink wall? :confused: Is that a special kind of filter? :p

Its usually 12dB/octave, and in some better cases 18 or 24dB per octave.

So if its set to 80hz and you got 24dB/oct., then at 40hz its down 24dB. Thats for the high pass filter.

The sub uses a low pass filter, which filters the freqs above one point. Again, usually 12dB, 24dB in some cases. So if you set it to 80hz, it will be down 24dB at 160hz.

[curtis]

I was probably thinking of money at the time and "Brinks".

Good thing bikeman didn't catch that. :)

[Mike^S]

Two or 3 speakers played at the same decibel level is only slightly louder than one speaker played at that level. Certainly dont suggest its additive or even anything close to that.


If the two speakers are right next to each other, the volume will be 6dB higher than one speaker. If they are several feet apart it will still be 4-5dB louder than a single speaker. Now if you add a third speaker, that will ad another 1-2dB. So you are looking at around 5-7dB louder compared to one speaker. That's pretty significant considering that you would have to quadruple the amount of power going to a single speaker to get that kind of increase in volume.

[GirgleMirt]

curtis: too bad I happened to like the term brinkwall. lol


If the two speakers are right next to each other, the volume will be 6dB higher than one speaker. If they are several feet apart it will still be 4-5dB louder than a single speaker. Now if you add a third speaker, that will ad another 1-2dB. So you are looking at around 5-7dB louder compared to one speaker. That's pretty significant considering that you would have to quadruple the amount of power going to a single speaker to get that kind of increase in volume.
Wow, thats about the most inconsistent math I've seen in my life :p ;)

Sound pressure level, doubles every 3dB. So if you double the speakers, you double the SPL, so it should increase by 3dB at most. Why/how 5-7 dB?

[Mike^S]

curtis: too bad I happened to like the term brinkwall. lol


Wow, thats about the most inconsistent math I've seen in my life :p ;)

Sound pressure level, doubles every 3dB. So if you double the speakers, you double the SPL, so it should increase by 3dB at most. Why/how 5-7 dB?

3dB is how much the volume increases when you double the power. When you double the speakers the volume goes up by 6dB. But that is only if the two speakers are right next to each other. If they are separated you will get less than that, probably around 4-5dB, as I said already.

Adding a third speaker will add another 1-2dB which is how you get 5-7dB.

[Mike^S]

Here is the math per Ed Mullen:

The difference in dB between any two sound pressure measurements is:

dB = 20 * log (Px/Py) (where Px and Py represent the two pressure levels)

If you double the sound pressure, then Px/Py = 2. Solving for the dB increase = 6.0206 dB. So a doubling of the sound pressure equates to a 6 dB increase in sound pressure.

Remember, you will only see a 6 dB increase when the two sound pressure sources are co-located and are identical in frequency, phase, and individual sound pressure.

Assuming each additional sub adds 3 dB is not correct as the number of subs grows. I know you are assuming incomplete acoustic coupling, but even then the math is not correct because you are dealing with log10 functions and they are not additive like that.

For the purposes of your comparisons, I would advise assuming complete acoustic coupling and using the following:

1 sub = baseline
2 subs = + 6 dB
3 subs = +9.5 dB
4 subs = +12 dB
5 subs = +14 dB
6 subs = +15.5 dB
7 subs = +17 dB
8 subs = +18 dB

[kinggimp82]

Why would you want to cross your 170's over with your sub @ 100Hz?

well my receiver only goes as low as 100 for x-over. my receiver is a lowend pioneer($179). i eventually want a nice reveiver.

id use the low level input but im lazy. also im confused to how they work if i want it for movie use. would my center (340 se) and surrounds (htm 200s) just produce more bass than the mains if i used my hsu stf-2 crossover? that really my main issue.