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Sub-woofer Power Amp: Engage 50 hz Filter?

Zooberwerx

Zooberwerx

Gold Supporting Member
Dec 21, 2002
23,315
28,109
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Virginia Beach, VA
#1
Riis's PA question of the day:

We're using a pair of budget Yorkie subs powered by a QSC RMX 1450 amp (~1400 watts at 4 ohm). I have the option of engaging either the 30 hz or 50 hz filters in an attempt to "tighten" low-end response. From what I understand, the fundamentals (B = 32 hz, E = 40 hz) are not nearly as critical as accurately reproducing the upper harmonic content when it comes down to low-end definition. What would be the appropriate application and are there other refinements I should consider?

Tomorrow's question: taming low-end boom, mud, and bumps with a parametric EQ?

Thanks

Riis
 
#3
modulusman said:
If you are using budget subs then I would use the 50hz filter. What subs are you using?
Click to expand...

I knew I could count on you, mm! The subs are the discontinued Yorkville Performance 18's (can't recall the model #). Each cab has a front-loaded single 18" driver but positioned at a 45 deg. downward angle. The drivers are non-original and rated at ~300 watts, 8 ohm. I'm driving them in bridged mono.

They are bottom-of-the-line but adequate for our purposes. Our mains are the Carvin 1523's (3 way with a 15") so we're able to get away with using a crossover threshold of 90-100 hz.

Riis
 
#4
Looking at the discontinued products list on the yorkville site and most the subs had a 50hz as the low number on the frequency response. I would say you would want to use the 50hz setting on the amp.
 
#7
Steve said:
I don't care if you have a wall of Meyer subs, use the 50hz if you want tight.

It's not like it kills 100% of everything 49hz or less.

IMHO YMMV
Click to expand...

I could not disagree with you more. Coming from a man that uses Meyer woofers (PSW-2) frequently, I call BS. I run a filter at....nothing. No compression, no dynamic compression, no equalisation etc. Wonderful 'tight' low end. Yes, it has active DSP with filtering and what not, but also has a useable response to 27Hz.

Yes, for Zooberwerx, the filter is necessary as his cabinet rolloff is not that low. For 'a wall of Meyer subs', not at all. Not every system is the same Steve.
 
#8
Micky-D said:
I could not disagree with you more. Coming from a man that uses Meyer woofers (PSW-2) frequently, I call BS. I run a filter at....nothing. No compression, no dynamic compression, no equalisation etc. Wonderful 'tight' low end. Yes, it has active DSP with filtering and what not, but also has a useable response to 27Hz.

Yes, for Zooberwerx, the filter is necessary as his cabinet rolloff is not that low. For 'a wall of Meyer subs', not at all. Not every system is the same Steve.
Click to expand...

Correct, I don't use the good stuff like Meyers....mine is more like "Oscar Meyers". BAHAHAHAHA!!

Accurate reproduction of the super-low freq's (27 hz!) requires a lot of power but is there any sonic benefit when addressing the small / mid size venues?

Riis
 
#9
Zooberwerx said:
Correct, I don't use the good stuff like Meyers....mine is more like "Oscar Meyers". BAHAHAHAHA!!

Accurate reproduction of the super-low freq's (27 hz!) requires a lot of power but is there any sonic benefit when addressing the small / mid size venues?

Riis
Click to expand...

I certainly think so. My approach has always been to have the flattest frequency response from my system and best audio experience for the crowd no matter what the size. And deep, low frequency sound I find adds a whole dimension to the overall mix. It makes the crowd percieve the sound as 'louder' and 'fuller' without ever touching the gain.

In my nice small tropical town of Townsville, we have a small venue called Riverway. It has a pair of 18" Dynacord active woofers, not sure of the model, but they wonderfully present low end material. It's a pleasure to mix and sounds fantastic.

Cheers,
Mick
 
#10
Don't forget with the RMX1450 (Which is identical to a Behringer EP1500, just in case you ever wanted to know) the 50hz filter produces a slight hump around 100hz. Bust out your RTA and see for yourself, after consulting my notes, it was almost 5dB up on my setup.

Edit:

Just checked the manual and its actually in there too.

Seriously though, its not going to hurt to try some things out. If you leave it flat and find that you need to do some cutting on your <75hz EQ bands, turn on the amp filter and flatten out the EQ. Similarly, if you turn on the filter and find that you need to boost on the EQ, turn it off. Its more about how it sounds in the room than what the numbers say on the box.
 
#11
JackANSI said:
Don't forget with the RMX1450 (Which is identical to a Behringer EP1500, just in case you ever wanted to know) the 50hz filter produces a slight hump around 100hz. bust out your RTA and see for yourself.

Edit:

Just checked the manual and its actually in there too.
Click to expand...

Thanks for the research. When all else fails, read the manual. I should be able to tame it with the Rane.

Riis
 
#13
Just skimmed, so if I missed something don't hate me ; }

Even with smaller or higher-tuned subs, I like the smoother 30 Hz setup that I find in QSC amps better than the humpy 50 Hz one. I find that handled right it can actually sound tighter and that any further adjustment can be handled with EQ, which is usually in use anyway. Also, realize that the Hz number usually means the response is 3 dB down by that point, so often a 40 Hz figure is actually what you'd want with a lot of these subs with +50 hz specs.

That's my take anyway.
 
#14
greenboy said:
Just skimmed, so if I missed something don't hate me ; }

Even with smaller or higher-tuned subs, I like the smoother 30 Hz setup that I find in QSC amps better than the humpy 50 Hz one. I find that handled right it can actually sound tighter and that any further adjustment can be handled with EQ, which is usually in use anyway. Also, realize that the Hz number usually means the response is 3 dB down by that point, so often a 40 Hz figure is actually what you'd want with a lot of these subs with +50 hz specs.

That's my take anyway.
Click to expand...

Funny you should mention that as I have the 40 hz filter engaged on the crossover. Guess I should have said something earlier but it slipped my mind.

Doug / dcr.....get back to work.

Riis
 
#15
The bump in the filter is only about 0.5 dB max.

The main benefit of the high-pass filter is to prevent speaker damage due to overexcursion. The 30 Hz filter setting will give you a little more low end, if you have much down there, but the 50 Hz setting is safer for the loudspeaker drivers.
 

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