using a home subwoofer as a PA-subwoofer (small event)

[dasdoing]

Hi guys. I am going to "test" my new PA speakers I bought by providing the sound for our neighborhood new-year party. it will be at a small open manual car-wash and the street infront, so my 2x 120dB(z) peak (line source) mains should easily take care. problem is they are made to be crossed at 100Hz or above, so I need a sub. my sub is not a PA sub though. it is prety strong though, in my room at least (using it in 3 o'clock position). I don't expect it to make a full PA subwoofer cause it is obviously not made for this (Kef Kube 12b). since it is rated 114dB max it should at least give me some bass though, so I hope. I also pretend to use the frontwall to add some gain. Now I see some problems beforehand and kindly ask here because I know that a lot of users here have advanced tecnical knowledge:

1) Is this a bad idea? can I damage my sub by playing it at it's limit? (I obviously will be very carefully increasing the volume)

2) the sub plays very deep (rated 22Hz and goes much deeper with room gain) and is sealed. should I use a highpass? at 30Hz-ish or higher?

3) does the low-pass point make any diference?

4) a nother option would be using my 2 old KRK Rokit 8's to provide the/some bass (would be lowpassing them at 100Hz)

 

[ernestcarl]

Hi guys. I am going to "test" my new PA speakers I bought by providing the sound for our neighborhood new-year party. it will be at a small open manual car-wash and the street infront, so my 2x 120dB(z) peak (line source) mains should easily take care. problem is they are made to be crossed at 100Hz or above, so I need a sub. my sub is not a PA sub though. it is prety strong though, in my room at least (using it in 3 o'clock position). I don't expect it to make a full PA subwoofer cause it is obviously not made for this (Kef Kube 12b). since it is rated 114dB max it should at least give me some bass though, so I hope. I also pretend to use the frontwall to add some gain. Now I see some problems beforehand and kindly ask here because I know that a lot of users here have advanced tecnical knowledge:

1) Is this a bad idea? can I damage my sub by playing it at it's limit? (I obviously will be very carefully increasing the volume)

2) the sub plays very deep (rated 22Hz and goes much deeper with room gain) and is sealed. should I use a highpass? at 30Hz-ish or higher?

3) does the low-pass point make any diference?

4) a nother option would be using my 2 old KRK Rokit 8's to provide the/some bass (would be lowpassing them at 100Hz)

According to Rythmik (my current sub), if you want to protect a sealed box and make it play louder, reduce/cut the infrasonic extension. Seems reasonable that should apply to other subs as well. Perhaps try a 24-36dB/octave HPF at 20-28Hz. If possible, maybe add a limiter/compressor DSP as well. Dunno about the low-pass, but why not just set it to whatever xo already works best with the mains.

 

[LTig]

Hi guys. I am going to "test" my new PA speakers I bought by providing the sound for our neighborhood new-year party. it will be at a small open manual car-wash and the street infront, so my 2x 120dB(z) peak (line source) mains should easily take care. problem is they are made to be crossed at 100Hz or above, so I need a sub. my sub is not a PA sub though. it is prety strong though, in my room at least (using it in 3 o'clock position). I don't expect it to make a full PA subwoofer cause it is obviously not made for this (Kef Kube 12b). since it is rated 114dB max it should at least give me some bass though, so I hope. I also pretend to use the frontwall to add some gain. Now I see some problems beforehand and kindly ask here because I know that a lot of users here have advanced tecnical knowledge:

1) Is this a bad idea? can I damage my sub by playing it at it's limit? (I obviously will be very carefully increasing the volume)

2) the sub plays very deep (rated 22Hz and goes much deeper with room gain) and is sealed. should I use a highpass? at 30Hz-ish or higher?

3) does the low-pass point make any diference?

4) a nother option would be using my 2 old KRK Rokit 8's to provide the/some bass (would be lowpassing them at 100Hz)

I wouldn't risk using Hifi equipment for any PA application. Loudness goes easily out of hands. A sub may clip a lot before it becomes audible in a negative way so both its amp and woofer may see much higher load/power than designed for. Better borrow a PA sub for one day at the local pro musicians shop.

 

[NiagaraPete]

I wouldn't risk using Hifi equipment for any PA application. Loudness goes easily out of hands. A sub may clip a lot before it becomes audible in a negative way so both its amp and woofer may see much higher load/power than designed for. Better borrow a PA sub for one day at the local pro musicians shop.

I concur. Renting a bass bin is not that expensive.

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[dasdoing]

thanks @ernestcarl

A sub may clip a lot before it becomes audible

now this is something I didn't know. I thought I would be able to hear it's limit. In that case I surely wont risk losing my beloved sub

Better borrow a PA sub for one day at the local pro musicians shop.

I concur. Renting a bass bin is not that expensive.

I will see if I get one here for cheap in the neighborhood. it's not that I am paid for the service, though; I might just stick to the mains only, it's not that important of an event and there will be no bass heavy music

 

[LTig]

[..] I might just stick to the mains only, it's not that important of an event and there will be no bass heavy music

In that case you won't miss anything below 100 Hz anyway. I own a pair of FBT Jolly 8ba (8" woofer / 1" compression horn tweeter) PA speakers and a single RCF PA sub (12" woofer) for my E-Drums, and I used the Jolly's without sub for a multi media show (male voice and soft background music) and the sub was not missed. FR of the Jolly 8ba begins to drop at 110 Hz.

 

[LTig]

now this is something I didn't know. I thought I would be able to hear it's limit.

Humans are bad in detecting THD at low frequencies in the first place. And then it might be even pleasing - if the sub is driven into clippling by a 40Hz tone playing too loud it will create harmonics at 80 Hz and 120 Hz which creates a "fuller" sound people may prefer over the clean tone.

 

[dasdoing]

In that case you won't miss anything below 100 Hz anyway. I own a pair of FBT Jolly 8ba (8" woofer / 1" compression horn tweeter) PA speakers and a single RCF PA sub (12" woofer) for my E-Drums, and I used the Jolly's without sub for a multi media show (male voice and soft background music) and the sub was not missed. FR of the Jolly 8ba begins to drop at 110 Hz.

nice. I can probably EQ mine to get output to 80Hz if I don't hit the limiter (gotta love the fact that PA stuff shows a light when on limit). it's a dubble 6" (plus horn) though. not made to play anything there *EDIT I actualy think it has a high pass there, for subwoofer matching. it's DSP is not acessible though

 

[LTig]

nice. I can probably EQ mine to get output to 80Hz if I don't hit the limiter (gotta love the fact that PA stuff shows a light when on limit). it's a dubble 6" (plus horn) though. not made to play anything there *EDIT I actualy think it has a high pass there, for subwoofer matching. it's DSP is not acessible though

Do you have a link to the speakers manual? Or specs?

 

[kyle_neuron]

Do you have a DSP to run your main speakers? Does it have a spare output channel for you to process your subwoofer? If so, just make sure to low and high pass the sub appropriately, and apply a reasonable limiter to prevent damage.

You can do the limiter at home. Connect up the sub via the DSP, apply the filters, and play a pink noise signal at high level into the DSP.
Turn the sub’s own volume control up fully (to avoid someone on the day of the event doing so when you’re not looking) and reduce the limiter threshold on the DSP until the subwoofer is not clipping, and excursion seems controlled.

It’s not scientific, but would do the trick. Ideally, you would use a multimeter on the DSP output channel and play a 60 Hz sine wave, then adjust the limiter until the DSP output voltage is below the maximum input voltage stated by the subwoofer manufacturer in the manual or spec sheet. Do that, if you can.

 

[Inner Space]

Don't do it. It takes immense acoustic power to make LF audible outdoors, and no domestic sub could get close. It will blow up for sure. Plus, what people at parties think of as LF punch is about 100Hz. You'll be fine with your mains only. Happy new year!

 

[dasdoing]

Do you have a link to the speakers manual? Or specs?

manual and ease file:

http://markaudio.com.br/downloads/manuais/MANUAL%20TECNICO%20HMK6.pdf

http://markaudio.com.br/downloads/easefocus/HMK6%20REV1.gll

they do measure semi-anechoic though

here it is without the grill in my room

Do you have a DSP to run your main speakers? Does it have a spare output channel for you to process your subwoofer? If so, just make sure to low and high pass the sub appropriately, and apply a reasonable limiter to prevent damage.

You can do the limiter at home. Connect up the sub via the DSP, apply the filters, and play a pink noise signal at high level into the DSP.
Turn the sub’s own volume control up fully (to avoid someone on the day of the event doing so when you’re not looking) and reduce the limiter threshold on the DSP until the subwoofer is not clipping, and excursion seems controlled.

It’s not scientific, but would do the trick. Ideally, you would use a multimeter on the DSP output channel and play a 60 Hz sine wave, then adjust the limiter until the DSP output voltage is below the maximum input voltage stated by the subwoofer manufacturer in the manual or spec sheet. Do that, if you can.

allready gave up on the idea. Kef stuff is expensive here in Brazil. wont risk my sub only to impress neighbours

Don't do it. It takes immense acoustic power to make LF audible outdoors, and no domestic sub could get close. It will blow up for sure. Plus, what people at parties think of as LF punch is about 100Hz. You'll be fine with your mains only. Happy new year!

You are right. Happy New Year

 

[LTig]

manual and ease file:

http://markaudio.com.br/downloads/manuais/MANUAL%20TECNICO%20HMK6.pdf

http://markaudio.com.br/downloads/easefocus/HMK6%20REV1.gll

Whatever an ease file is - the data look familiar to my Jolly 8ba, just two 6.5" woorfs vs. one 8" woofer, and more power and I think a DSP crossover. My knowledge of portuguese (?) is nil but I recognize familiar words.

 

[kyle_neuron]

Oh, you're in Brazil! Well, now I have some context. It may be the nature of the work I do, but all the Brazilians I met expected loud to be loud.

Here's some output from the GLL data for your speakers:

The shaded areas indicate the region of validity for the measurement setup.

My suggestion was to add some general extra low end, but no. You'll probably be fine without, and it's too much effort and risk when I'm sure you just want to revel in being able to be together with music! So na maciota, right?!

 

[dasdoing]

Whatever an ease file is - the data look familiar to my Jolly 8ba, just two 6.5" woorfs vs. one 8" woofer, and more power and I think a DSP crossover. My knowledge of portuguese (?) is nil but I recognize familiar words.

the speaker is DSP corrected, yes

Whatever an ease file is

you can use it with Ease software to simulate your PA setup: https://www.afmg.eu/en/ease-enhanced-acoustic-simulator-engineers
normaly you have these for line source speakers only, your speaker is a point source

It may be the nature of the work I do

what do you work with?

Brazilians I met expected loud to be loud

My suggestion was to add some general extra low end, but no. You'll probably be fine without

I suspect that the speaker is loud enough that I will actualy have lot of headroom. will run some REW sweeps and try to get at least more 80Hz for the kick. the speaker has protections and limiters