I did not know where to post this but since I am using limiters to protect subwoofers I decided that this forum would be OK.
Admin: Feel free to relocate this.
I am still a little confused about limiters on amps and in processing equipment.
If, for example on a Crown xti-1002, I set limiter to 30 Volts and the nominal listed driver impedance is 4.29 Ω in factory documentation, would that equal ~ 210 Watts RMS limit?
.
Or, is the 30 Volts a peak level meaning that the power is limited to 210 W peak or ~ 150 Wrms?
.
And, when I check the complete speaker box with DATS I see values of:
75 Ω at 20 Hz
11 Ω at 40 Hz
6.1 Ω at 60 Hz
.
Since this is the frequency range that I am interested in, can I count on the limiter to do anything than limit peak voltage and assume that I really do not know the power levels that I am driving the speakers to?
.
Also, does the limiter setting equate with the Eg that I set in Hornresponse?
.
Is it useful in determining what limiter level roughly coincides with a certain Xmax.
.
Are there any documents on the web that would explain this to me in more depth?
.
I am sorry to be so uneducated on this subject, but I really want to understand.
Thank You,
Dave
Admin: Feel free to relocate this.
I am still a little confused about limiters on amps and in processing equipment.
If, for example on a Crown xti-1002, I set limiter to 30 Volts and the nominal listed driver impedance is 4.29 Ω in factory documentation, would that equal ~ 210 Watts RMS limit?
.
Or, is the 30 Volts a peak level meaning that the power is limited to 210 W peak or ~ 150 Wrms?
.
And, when I check the complete speaker box with DATS I see values of:
75 Ω at 20 Hz
11 Ω at 40 Hz
6.1 Ω at 60 Hz
.
Since this is the frequency range that I am interested in, can I count on the limiter to do anything than limit peak voltage and assume that I really do not know the power levels that I am driving the speakers to?
.
Also, does the limiter setting equate with the Eg that I set in Hornresponse?
.
Is it useful in determining what limiter level roughly coincides with a certain Xmax.
.
Are there any documents on the web that would explain this to me in more depth?
.
I am sorry to be so uneducated on this subject, but I really want to understand.
Thank You,
Dave
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Dave,
This is a decent article in general:
How To Set a Limiter for Subwoofers | BASSMAXX Blog
1) Most nominal impedance figures are even numbers, 2, 4, 6, 8, 16 ohms.
The IEC standard (IEC60268-3) allows any impedance above the rated value, but limits the impedance below. It does not allow the rated impedance to fall below the 80 % of the nominal value at any frequency.
Your speaker's DC resistance may be 4.9 ohms, and most cabinets are pretty close to the DCR at some point in the impedance curve, usually at Fb.
Since the voice coil is moving the least at Fb it does not dissipate heat as well, so if your music program has a lot of signal around that frequency it could be an important consideration.
Limiters can be peak or RMS, or a combination dependent on attack and release, or two separate settings, peak and average, but all are based on voltage, consult the user manual of your DSP to determine what they are.
2) The limiters are voltage based, the voltage will result in more power at the lower points in the impedance curve.
3) Yes.
4) Unfortunately, excursion may be highest at frequencies that have fairly high impedance, so limiters that are not frequency based (as in a side chain EQ insert) won't offer excursion protection. Generally if the HP filter is set properly (about 1/6 octave below Fb 24 BW) thermal damage will occur before mechanical damage. If excursion is a concern, limiters can be set while looking at a white dot on the cone, adjust the limiter downward so the peak to peak excursion is only just over 1/2 the Xmax figure.
Art
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That method really makes sense to me.
This is for a Lab 12 based ML_TL where HR says 140 Watts hits X-Max, so it is definitely excursion limited.
That said, if they were operated at X-Max, I think my house would fall down.
I generally see only 4 or 6 mm of max Peak to Peak excursion, and that is pretty loud in my concrete house.
Thanks for the links,
Dave
Originally Posted by weltersys:
If excursion is a concern, limiters can be set while looking at a white dot on the cone, adjust the limiter downward so the peak to peak excursion is only just over 1/2 the Xmax figure.
I should have wrote:
"If excursion is a concern, limiters can be set while looking at a white dot on the cone, adjust the limiter downward so the peak to peak excursion using band passed pink noise is only just over double the Xmax figure."
X max is one way excursion, the Lab 12 has an Xmax of 13mm, so seeing a peak to peak excursion of 26 mm is no problem.
On my ported Lab 12s I put the grill cloth at a distance so when the surround starts slapping it (around 30 mm peak to peak) I know it's time to "back 'er down" a bit 😉.
With only 4 or 6 mm of peak to peak excursion, you are just tickling the Lab 12s.
Art
If excursion is a concern, limiters can be set while looking at a white dot on the cone, adjust the limiter downward so the peak to peak excursion is only just over 1/2 the Xmax figure.
Dave,
I should have wrote:
"If excursion is a concern, limiters can be set while looking at a white dot on the cone, adjust the limiter downward so the peak to peak excursion using band passed pink noise is only just over double the Xmax figure."
X max is one way excursion, the Lab 12 has an Xmax of 13mm, so seeing a peak to peak excursion of 26 mm is no problem.
On my ported Lab 12s I put the grill cloth at a distance so when the surround starts slapping it (around 30 mm peak to peak) I know it's time to "back 'er down" a bit 😉.
With only 4 or 6 mm of peak to peak excursion, you are just tickling the Lab 12s.
Art
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You don't say what you are trying to protect your woofers from. Really a threat?
Limiting is a horrible idea in terms of sound. None is best. There are always brief big peaks in classical music, like choral. So you don't want to turn those peaks in momentary distortion.
If your system is dysengineered so that the amp can really cook the drivers if an RCA plug came loose, then maybe at some very large power you can put in the cork.
Ben
Limiting is a horrible idea in terms of sound. None is best. There are always brief big peaks in classical music, like choral. So you don't want to turn those peaks in momentary distortion.
If your system is dysengineered so that the amp can really cook the drivers if an RCA plug came loose, then maybe at some very large power you can put in the cork.
Ben
Thank you, once again
Every time I post a serious (to me) question here, I learn something, usually allot.
I upped the limiter voltage at first cautiously but then quickly until they were turned off.
With the gain levels on my system and the impedance curve of the actual speaker in the cabinet, it seems that only the HP filter is required.
I get a peak to peak stroke of about 20 to 25 mm on average (base heavy) material and measured about 25 mm with the (pink?) noise source in REW turned up so that the input meters read about -8 dBFS on the digital input meters on the DEQ2496.
Odd that it takes REW to be set at -8 dBFS to get this response.
I also did some 20 to 200 Hz sweeps and watched the little piece of yellow-post it at the center of the speakers just for comparision.
.
So once again I learned allot, mainly that:
OH MY GAWD, these things are ferocious and angry when I unleash them.
Thank you everyone, just remember I eventually get it even if I sound a little dense at first.
Thanks,
Dave
Every time I post a serious (to me) question here, I learn something, usually allot.
I upped the limiter voltage at first cautiously but then quickly until they were turned off.
With the gain levels on my system and the impedance curve of the actual speaker in the cabinet, it seems that only the HP filter is required.
I get a peak to peak stroke of about 20 to 25 mm on average (base heavy) material and measured about 25 mm with the (pink?) noise source in REW turned up so that the input meters read about -8 dBFS on the digital input meters on the DEQ2496.
Odd that it takes REW to be set at -8 dBFS to get this response.
I also did some 20 to 200 Hz sweeps and watched the little piece of yellow-post it at the center of the speakers just for comparision.
.
So once again I learned allot, mainly that:
OH MY GAWD, these things are ferocious and angry when I unleash them.
Thank you everyone, just remember I eventually get it even if I sound a little dense at first.
Thanks,
Dave
Dave,
Going from 6 mm peak to peak to 24 mm peak to peak is about 12 dB difference.
At 1000 Hz, a ten dB change sounds twice as loud, but at 20 Hz, it only takes a 5 dB change to sound twice as loud, so now you have experienced some low bass more than four times louder than you had been running.
Evidently got your attention ;^).
Art
Going from 6 mm peak to peak to 24 mm peak to peak is about 12 dB difference.
At 1000 Hz, a ten dB change sounds twice as loud, but at 20 Hz, it only takes a 5 dB change to sound twice as loud, so now you have experienced some low bass more than four times louder than you had been running.
Evidently got your attention ;^).
Art
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