b&c 21sw152-8 voltage question

[abraham]

hi everyone

can you help me to know 

how many volts does b&c 21sw152-8ohms can handle long term in order to set amp limiting?

im using a crown itech 9000hd in mono config with a pair of subs at  a total of 4 ohms  charge in parallel

i have been testing voltage with a uni-t multimeter

thanks in advance

 

[peniku8]

The driver can handle around 400-500W true long term average power, which is about 55V at Zmin. You'll have to find out the minimum impedance of the driver in the cab to be sure, but pure voltage limitation isn't ideal anyways.

[abraham]

I have already tested tone 60 to 100 hz with multimeter reading 160 volts,but i dont know how many volts long term it can handle

 

[SME]

1 hour ago, abraham said:

I have already tested tone 60 to 100 hz with multimeter reading 160 volts,but i dont know how many volts long term it can handle

 

That depends on the impedance at that frequencies of interest, which depends on the cabinet design.  Also, long-term is a very loaded word.  How long is long-term  One second?  One minute?  One hour?  One full day?  Those are all likely to have different answers, and the longer durations will also depend on the cabinet ventilation and ambient air characteristics.  To echo @peniku8, pure voltage limiting is not ideal.  The driver can probably take 3-4X as much or more voltage (meaning at least 9-16X power!) in the very short term than it can take in the very long-term.  A "fool-proof" voltage limit setting will completely waste your amp's potential.  Anything higher and you can certainly fry the driver if you try hard or screw up bad.

So ideally, you want a limiter that's based on actual power output over time and that responds relatively slowly so that it doesn't get in the way with normal music.  I have no idea what limiter options you have available to you, but it's also helpful to consider what kind of content you're going to play, including the crest factor, which is the ratio (in dB) between peak and average signals.  There's a huge difference between signal that peaks hot for kick drum every 60 bpm and EDM bass drones that might blast the sub at its port tune frequency with square-wave like signals for an entire track.

[peniku8]

A nice video on the topic by Bennett Prescott, B&C US sales manager:

 

[abraham]

I need 5 hours working the sub, i know tone test is very diferent to real music audio data and i know there is peaks in data music and nominal data in music ,i am trying to find how much is too much power and how much is a waste for the sub , i have never used 6 inch voice coils in subs and never have used 2000 rms subs ,in the past i aleays used 4 inch voice coils for 18 inch subs and crown macrotech 2400 , now im using crown itech 9000 in mono for 2  21 inch subs

 

 

 

[Ricci]

Hello Abraham...It depends.

The usage and material being put through the subs make a big difference. If we consider that the B&C rating is 1700w continuous and the min impedance will be somewhere around 5.5 to 6 ohm in a cabinet, it seems like a starting point of about 100v would be suitable. This may need to be adjusted up or down depending on the specific use case, but this seems a reasonable starting point. I'd advise watching the video from Bennett posted above. 

As previously mentioned a strict peak voltage limiter isn't the best for this type of job.