Sub Watt rating?

[Frisbee78]

Hi all.
I have a sub made by Jamo called Pro Sub 1000ex.

At the back I read:
- long term power 2x300W
- short term power 2x500W

How short is short term and how long is long term? Am I right to assume that these Watts are RMS?

Thx

[janneman]

I have never seen a clear definition of long term and short term. Is there not more info on the Jamo website?
I personally would interprete long term as being save to connect it to an amp of that power. If you use a higher power amp (say 500) I would try to make sure that it is not always at max volume.

RMS? Don't know. From the type number (1000ex) I assume they sell it as a 1000W sub. I would GUESS that that's music power or whatever, and that the RMS power handling is less. But I am just reasoning backwards from the fact that they always want to show the largest numbers, and RMS normally is the lowest number.

Anyway, I would feel comfortable with "normal" use with an amp up to 200W (RMS) or so.

But, as they say, YMMV

Jan Didden

[bjtaudio]

Yes it is most likely the power ratings are RMS figures however that are usually based on a duty cycle say for long term power might mean 10 minutes on and 10 minutes off and for short term it would be say 1 second on and 1 minute off, however this may depend on the manufacture to waht the actual duty cycle times are.

You could try getting in contact with Jamo or a distributor and they may be able to tell you or find out for you the exact figure.

I believe there is an actual standard however.. I had a quick search arround and cannot locate the artical where I read about it, sorry.

However, If your worried about overdriving the sub woffer with a big or over sized amplifier.. I have found it's better to have a big amp giving a little more headroom than to have a smaller amplifier clipping..If a speaker has a continous rms power rating of 200 Watts a 200 ~ 300 Watt amp is fine provided it's not clipped!

Note music program is dynamic up and down (dutycycled) is not a constant sine wave from a signal generator for example! We'll you hope it's not? the music these days..bass cd's for example.

Another options exist either keep the volume under control, or use a compressor. Some powered subwoffers include this in thier designs to save the driver! and prevent an expensive reapair bill for the customer.

hope I helped,
cheers Bevan.

[Frisbee78]

Thanks for your inputs

I intend to power the sub with a 2x350W RMS / 1x1kW RMS amp I am working on.
I don't think the amp clips but I'll double check that when I finish it! I now there is a DC protection if anything.
It also has a pair of (pretty cool) RMS/peak wattmeters so I'll be able to keep an eye on what is being fed to the sub and control the volume acordingly.

Unfortunately, there is nothing on Jamo's website about discontinued products but I'll try to contact them to get more details. I don't want to do any damage here

[janneman]

Originally posted by bjtaudio
Yes it is most likely the power ratings are RMS figures [snip]Bevan.

What I mesant is that they most probably are NOT RMS values. The fact that it is not specified almost always means that there is a much more loosely spec, like music power. RMS would be lower, so they don't want to spec that.

Jan Didden

[Frisbee78]

What I mesant is that they most probably are NOT RMS values. The fact that it is not specified almost always means that there is a much more loosely spec, like music power. RMS would be lower, so they don't want to spec that.

I would be tempted to agree... Danm marketing people

Even though, professional gear is sometimes rated in real Watts... (can you imagine going to an Oasis concert and seeing all the speakers going down because of a misunderstanding on the power rating? )

Hopefuly Jamo will be able to tell me. I don't want to hasard a guess.