Yes, it can be thot of as mass loading. I don’t currently know of a way to simulate this, but i am sure you could.
dave
i dont actually understand.. however, the sims were quite rough, filters etc kinda slapped on (ive yet to learn about designing crossover slopes etc. saving that for later!) and the eq was just to see how much boost i could get within xmax with a lower tune.
basically it was more to ask if the concept is a valid one to persue:
should i go for a higher tune, which allows sub to produce more spl, and have better f3/6/10 naturally,
or should i go for a lower tune, which, if not equalised, gives a less optimal response, but, can go lower and can be equalised more heavily, giving up spl for extension ( i dont really need spl above what the mains can deliver after all.. )
It's actually very unusual for a sub to just overheat or explode by going a little over RMS, and especially not if you're hi-passing at 130Hz. The relative levels of raw RMS sound power in most music above 130Hz is surprisingly minimal - even the sort of music you would think was relatively thin on bass.
And for music that actually is thin on bass it's not much different - the ear is just that much more sensitive to the higher frequencies that they simply don't need to be played long and loud. -6dB is 25% amp power after all!
The thing to watch out for is long sustained tones and maximum or near maximum amplitude tones - like from a synthesiser (set up by someone who doesn't appreciate the musical benefit of a good ADSR envelope) or a microphone feedback loop - or even a 50Hz mains hum if you were unlucky enough to have the gain up at silly levels.
It's a mistake to assume this will never happen as it only needs to happen once, but if you're really careful with your system and you set it up in one predictable way it's reasonable to run the speakers to twice their RMS (or 'program power') with music program. No real music has tones so long and high amplitude as to burn a coil with just program power levels. Peak power levels is another matter and the only way to run them safely is with a limiter. Many limiters will have an RMS and Peak function.
The peak is most useful when you know that your amp actually has a power rating near to or above the max rating of the driver (or if you're really going to be hammering it a lot and just want to look after the long term health of the driver by setting it lower than it can handle), and RMS to stop those sustained high amplitude tones getting through.
Again if you're running your system for home hifi purposes these are really belt and braces measures to protect damage and won't impact on the listening experience in any way. But for your needs you probably don't need them. Just get an amp specced at around RMS or a little higher, and if you ever find it lacking you could always upgrade. 2x RMS is only +3dB anyway so you'd not be missing out on much.
And for music that actually is thin on bass it's not much different - the ear is just that much more sensitive to the higher frequencies that they simply don't need to be played long and loud. -6dB is 25% amp power after all!
The thing to watch out for is long sustained tones and maximum or near maximum amplitude tones - like from a synthesiser (set up by someone who doesn't appreciate the musical benefit of a good ADSR envelope) or a microphone feedback loop - or even a 50Hz mains hum if you were unlucky enough to have the gain up at silly levels.
It's a mistake to assume this will never happen as it only needs to happen once, but if you're really careful with your system and you set it up in one predictable way it's reasonable to run the speakers to twice their RMS (or 'program power') with music program. No real music has tones so long and high amplitude as to burn a coil with just program power levels. Peak power levels is another matter and the only way to run them safely is with a limiter. Many limiters will have an RMS and Peak function.
The peak is most useful when you know that your amp actually has a power rating near to or above the max rating of the driver (or if you're really going to be hammering it a lot and just want to look after the long term health of the driver by setting it lower than it can handle), and RMS to stop those sustained high amplitude tones getting through.
Again if you're running your system for home hifi purposes these are really belt and braces measures to protect damage and won't impact on the listening experience in any way. But for your needs you probably don't need them. Just get an amp specced at around RMS or a little higher, and if you ever find it lacking you could always upgrade. 2x RMS is only +3dB anyway so you'd not be missing out on much.
Last edited:
ahh its actually the alpair 7 fullrangers im talking about.. (sorry wrong forum) however im trying to get a feel of how loud they will actually go, so i can design the sub to be tuned to their performance range.
with a highpass at 130 hz, their excursion is obviously minimal.. however they are rated thermally for 20w. so sticking 150w into them, even if xmax is still ok, has to melt the voicecoils no?
with a highpass at 130 hz, their excursion is obviously minimal.. however they are rated thermally for 20w. so sticking 150w into them, even if xmax is still ok, has to melt the voicecoils no?
Well you would think so, but it still highly depends on music program and if you're running it with the limiters I mentioned.
To answer your basic questions: No. Excursion has no casual link to likelihood of thermal damage. And yes. Running them at 150w puts them at a significant risk of frying.
That's no reason not to use a 150w amp provided you have an adequate limiter though (RMS and peak functions both required).
You would be flying dangerously to use the whole of the 150w but if you know exactly what sort of music program you're going to be playing, you could definitely get away with it.
The thing about peak ratings is they're not to be taken absolutely literally. They just take the RMS rating of the driver (usually derived from pink noise or something like that), and add 6dB peaks to that.
I'm not sure the exact details of the standards use but I can't imagine any honest manufacturer would use pink noise that didn't include the full range that the driver is specified to reproduce (look for that rating on the spec sheet), at the very least.
With some music, the actual amount of content above 120Hz is negligible. ie:
That'll be some form of techno/edm almost undoubtedly - but if you download the free Reaper DAW and a free version of a plugin like the one pictured, you can watch your music and see where the distribution of energy really lies.
To answer your basic questions: No. Excursion has no casual link to likelihood of thermal damage. And yes. Running them at 150w puts them at a significant risk of frying.
That's no reason not to use a 150w amp provided you have an adequate limiter though (RMS and peak functions both required).
You would be flying dangerously to use the whole of the 150w but if you know exactly what sort of music program you're going to be playing, you could definitely get away with it.
The thing about peak ratings is they're not to be taken absolutely literally. They just take the RMS rating of the driver (usually derived from pink noise or something like that), and add 6dB peaks to that.
I'm not sure the exact details of the standards use but I can't imagine any honest manufacturer would use pink noise that didn't include the full range that the driver is specified to reproduce (look for that rating on the spec sheet), at the very least.
With some music, the actual amount of content above 120Hz is negligible. ie:
That'll be some form of techno/edm almost undoubtedly - but if you download the free Reaper DAW and a free version of a plugin like the one pictured, you can watch your music and see where the distribution of energy really lies.
Last edited:
thanks a lot for the education.
basically im thinking a 400wrms class-d amp for each the sub, and a circa 100 wpc t-amp for the dual-driver alpairs. since the alpairs appear to be 5 ohm speakers, and ill probably wire them in series, the amp will output significantly less than 100w.
ill never need more than 400w for the subs i imagine, although they are rated for 600.
in the end its all just to balance the kit im building/buying. i will spend 99% of my time listening at modest levels.
as mentioned earlier, how do i interpret amplifier apparent load in VA in winisd?
if i put 150w into the sub in winisd, but add heavy eq, i get an apparent load on the amp peaking at 700 va.. so how does that relate to the amp rating i need to avoid clipping ?
basically im thinking a 400wrms class-d amp for each the sub, and a circa 100 wpc t-amp for the dual-driver alpairs. since the alpairs appear to be 5 ohm speakers, and ill probably wire them in series, the amp will output significantly less than 100w.
ill never need more than 400w for the subs i imagine, although they are rated for 600.
in the end its all just to balance the kit im building/buying. i will spend 99% of my time listening at modest levels.
as mentioned earlier, how do i interpret amplifier apparent load in VA in winisd?
if i put 150w into the sub in winisd, but add heavy eq, i get an apparent load on the amp peaking at 700 va.. so how does that relate to the amp rating i need to avoid clipping ?
Can you even get T-amps that big? They are getting kinda dated. You might well be better with a smaller, but good class ab amp. 25-40w.
That is the DCR, they are nominal 8 ohm drivers.
dave
Well you're pushing the edges of my understanding but I'm pretty sure that's the same as the driver's resistance peak. Meaning although the amp is seeing that load, the driver is resisting it.
If someone smarter than me doesn't answer by the morning I'll have a look into it as I'd like to understand too, but that's the line of thinking to go down - what does the resistance actually mean in terms of current reaching the driver? Is that wasted in the amp and never reaches the coil, or does it get there but has a very weak effect? I'm not sure. If the latter it seems that in theory a sustained high amplitude tone on that precise frequency would be fairly disastrous for the driver.
But those sustained high amplitude tones (enough to blow a driver) are definitely the exception not the rule.
If someone smarter than me doesn't answer by the morning I'll have a look into it as I'd like to understand too, but that's the line of thinking to go down - what does the resistance actually mean in terms of current reaching the driver? Is that wasted in the amp and never reaches the coil, or does it get there but has a very weak effect? I'm not sure. If the latter it seems that in theory a sustained high amplitude tone on that precise frequency would be fairly disastrous for the driver.
But those sustained high amplitude tones (enough to blow a driver) are definitely the exception not the rule.
something like this would be better than a t-amp? 50wpc into 8 ohms..
LM3886 Stereo audiophile Amplifier Board 2x68W / 4 Ohm - Audiophonics
and also yes, t-amps are available at 90wpc (and much more)
LJ TA2022 V 1.2 Module Amplificateur Class T 2x90W 4 ohms - Audiophonics
i had a 90wpc one a few years ago..
youll need google if you dont speak french!
LM3886 Stereo audiophile Amplifier Board 2x68W / 4 Ohm - Audiophonics
and also yes, t-amps are available at 90wpc (and much more)
LJ TA2022 V 1.2 Module Amplificateur Class T 2x90W 4 ohms - Audiophonics
i had a 90wpc one a few years ago..
youll need google if you dont speak french!
Think in terms of voltage and headroom. If you boost a certain range by 10 or 20dB, how much more voltage is that? That becomes your limit, if you want to never clip.
As Hemisphere points out, power is not equal across the musical spectrum. I've found that the hottest part of most music lies in the 45-70Hz range. That's your subs.
See here: Spectrum of Musical Genres Be sure to look at the graph with peak levels if you want to avoid clipping.
FWIW, I used to run the little Peerless TC9FD in open baffle crossed at 700Hz. I limited the amp to 35V (about 150W) and only blew one once, running a test sweep thru it. They are rated at 30W.
As Hemisphere points out, power is not equal across the musical spectrum. I've found that the hottest part of most music lies in the 45-70Hz range. That's your subs.
See here: Spectrum of Musical Genres Be sure to look at the graph with peak levels if you want to avoid clipping.
FWIW, I used to run the little Peerless TC9FD in open baffle crossed at 700Hz. I limited the amp to 35V (about 150W) and only blew one once, running a test sweep thru it. They are rated at 30W.
so.. how much more voltage is it?
basically, if i want to use a specific eq, how do i calculate which amp rating i need? obviously more than the 150w input i specified in winisd..
bear in mind that VA, power factor etc are a mystery to me. i understand volts, amps and watts intuitively.. but VA ..err.. no. -and yes, ive read a number of explanations..
its also entirely new to me to think of amps in terms of volts.
ok so ive had a revelation ( possibly an embarrasing one) that decibels of gain can be converted to a voltage multipler.
so, if i understand correctly, and 8db eq boost equates to a circa 2.5x voltage increase
givent the 150w signal was 22.9v, the minimum voltage rating for the amp should be.. 57.2 ish volts? which should equate to a ermm.. ouch.. a 934 watt amp with these speakers.
is that right? blimey if so.
so, if i understand correctly, and 8db eq boost equates to a circa 2.5x voltage increase
givent the 150w signal was 22.9v, the minimum voltage rating for the amp should be.. 57.2 ish volts? which should equate to a ermm.. ouch.. a 934 watt amp with these speakers.
is that right? blimey if so.
Well I still like the Tripath chips and the TA2020 has always been my fave.
Do not believe that website, it's a pure lie. You'd be pushing it to get 20 WPC out of it, or 40W peak into 4 ohms. I know, I've had dozens of them. And I ran a very popular T-Amp website with over a million hits.
The TA2020 is sweet, but no where near 90 WPC.
Do not believe that website, it's a pure lie. You'd be pushing it to get 20 WPC out of it, or 40W peak into 4 ohms. I know, I've had dozens of them. And I ran a very popular T-Amp website with over a million hits.
The TA2020 is sweet, but no where near 90 WPC.
Correct. And 10dB is a voltage gain of about 3X.
No
Just think of it this way. Your amp have a maximum output voltage before clipping. If you boost any frequency range by 8dB, then that range will clip 8dB sooner than everything else. In effect, you just lowered everything else by 8dB.Typically an amp rated at 100 WPC will have a maximum clean output voltage of 28V RMS. That's now your boosted range. Everything else is pushed down 2.5X, or now at ~11V RMS. It's more complex than that for several reasons, but you get the idea.
There is a cheat, you can guess it by looking at the musical spectrum.
or.. can i just assume a 400wpc amp such as this one:
http://www.audiophonics.fr/images2/6945/IRS2092_Stereo_Amplifier.pdf
would have sufficient headroom?
hehe sorry im always looking for shortcuts
http://www.audiophonics.fr/images2/6945/IRS2092_Stereo_Amplifier.pdf
would have sufficient headroom?
hehe sorry im always looking for shortcuts
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.