RH450 + 1 x RS210 can I crank to full without fear of damage?

[charic]

[quote name='Bill Fitzmaurice' timestamp='1319118363' post='1410141']
Power ratings are moot. What matters is displacement. AFAIK only Barefaced reveals the displacement of their cabs. It's worth a look at Alex's site to learn what displacement is, why it matters, and ponder why every manufacturer doesn't provide it.
[/quote]

How is a power rating moot when the question at hand is can I turn my amp to full without breaking the cab?

[alexclaber]

[quote name='charic' timestamp='1319119073' post='1410160']How is a power rating moot when the question at hand is can I turn my amp to full without breaking the cab?[/quote]

Because it's only half the picture and not the important part. Speakers have to move to generate sound and the amount they can move limits power handling in a mechanical sense. The voice coils in speakers get hot and the amount of heat they can handle limits power handling in a thermal sense. With bass cabs 95%+ of the time you run into the mechanical limit before you reach the thermal limit. The standard power handling rating is unfortunately the less relevant thermal limit.

[charic]

[quote name='alexclaber' timestamp='1319119546' post='1410170']

Because it's only half the picture and not the important part. Speakers have to move to generate sound and the amount they can move limits power handling in a mechanical sense. The voice coils in speakers get hot and the amount of heat they can handle limits power handling in a thermal sense. With bass cabs 95%+ of the time you run into the mechanical limit before you reach the thermal limit. The standard power handling rating is unfortunately the less relevant thermal limit.
[/quote]

So in real world application the power rating is pretty much utter ollocks then as your going to hit the mechanical limit first?

Well that sucks! Based on that I would say it probably wouldn't be the brightest thing in the world to run it full out then. That day will have to wait until I'm running a 2nd 210 or a 212 then. Hopefully I won't need it anyway!

[Bill Fitzmaurice]

[quote name='charic' timestamp='1319119073' post='1410160']

How is a power rating moot when the question at hand is can I turn my amp to full without breaking the cab?
[/quote]
I already told you. Go to the Barefaced site and read why displacement, not thermal power ratings, is what's pertinent.

[4 Strings]

Just to repeat what someone else said, use your ears. You'll hear any distress way before it all goes wrong, its carrying on when the cab is in having trouble that causes damage. You've got loads of power available, using two cabs raises one off the ground and the difference just this makes in volume for monitoring is amazing.

Oh, just to add, listen to people like Bill and Alex.

Edited October 20, 2011 by 4 Strings

[charic]

Yeah I know to listen to Bill and Alex, incredible amounts of knowledge in the ol' amplification lab and can probably tell me all sorts of reasons why I shouldn't be using an RS210 but hey, it sounds good!

Really though, I know the basics about listening to the cab etc I just wondered whether anyone had any experiences with this turning this combination up to full volume and whether they had any issues.

[xgsjx]

Don't listen to any of them Cha, they're full of fairy dust.
What to do is turn every dial fully clockwise, plug your bass in & do the same with that, turn the power on, hold an E power chord with the open low E & whack those strings as hard as you can.
You'll be fine!

[alexclaber]

To address the specific problem, the real power output of the RH450 is ~130W into 8 ohms. The RS210 can handle 250W thermally so you can't overheat it. The woofers in the RS210 have small magnets (hence the low-ish weight for a ferrite thick-walled cab) and their sensitivity isn't that low so their maximum linear excursion must be low, thus I'd guess that the cab can handle somewhere around 100W before distortion/compression increases rapidly due to over-excursion (passing the mechanical limit) and you start to approach the failure point. As the RH450 only produces 130W into this load you're not going to be able to push the cab so hard that you reach the mechanical failure point (although you may hear some harmless distortion) so crank it to your heart's desires without fear!

[charic]

[quote name='xgsjx' timestamp='1319147138' post='1410673']
Don't listen to any of them Cha, they're full of fairy dust.
What to do is turn every dial fully clockwise, plug your bass in & do the same with that, turn the power on, hold an E power chord with the open low E & whack those strings as hard as you can.
You'll be fine!





[/quote]

I don't have an open E as I'm drop tuned to C will that suffice?

[charic]

[quote name='alexclaber' timestamp='1319197712' post='1411121']
To address the specific problem, the real power output of the RH450 is ~130W into 8 ohms. The RS210 can handle 250W thermally so you can't overheat it. The woofers in the RS210 have small magnets (hence the low-ish weight for a ferrite thick-walled cab) and their sensitivity isn't that low so their maximum linear excursion must be low, thus I'd guess that the cab can handle somewhere around 100W before distortion/compression increases rapidly due to over-excursion (passing the mechanical limit) and you start to approach the failure point. As the RH450 only produces 130W into this load you're not going to be able to push the cab so hard that you reach the mechanical failure point (although you may hear some harmless distortion) so crank it to your heart's desires without fear!
[/quote]

Thanks for that, makes for an interesting read too!

Does the fact that it is "louder than it's watts" make any kind of difference though, this is where I get confused tbh! 450 TCE watts have been proved not to be real world watts (although watts mean sod all anyway) however they reproduce a volume similar the standard output from a 450-500w head.

The bit that is a little stuck in my head is the fact that it's recreating these kind of volume levels which surely must translate into the speakers moving the same amount as they do for a standard 450-500w head (I know all these figures are for 4 ohms but it's easier to explain this way around). If they are moving that much then does that mean that damage can still be caused even though the real world watts would be nicely within spec?

Yours Confusededly
Charic

[xgsjx]

Drop C is even better!!!

I'd like to try a bunch of 450-500w rated heads & put them one after the other through the same cab & see how each compares in Db.

Alex, I dare say you've already tried this?

[Bill Fitzmaurice]

[quote name='alexclaber' timestamp='1319197712' post='1411121']
To address the specific problem, the real power output of the RH450 is ~130W into 8 ohms. The RS210 can handle 250W thermally so you can't overheat it. The woofers in the RS210 have small magnets (hence the low-ish weight for a ferrite thick-walled cab) and their sensitivity isn't that low so their maximum linear excursion must be low, thus I'd guess that the cab can handle somewhere around 100W before distortion/compression increases rapidly due to over-excursion (passing the mechanical limit) and you start to approach the failure point. As the RH450 only produces 130W into this load you're not going to be able to push the cab so hard that you reach the mechanical failure point (although you may hear some harmless distortion) so crank it to your heart's desires without fear!
[/quote]I wouldn't be so sure. That amp seems to have a very high compression ratio, the source of the magic 'TC watts', so the power density will be higher than the actual voltage swing capacity would indicate. Short term that's not a problem, but between that and the heat retention of ferrite drivers long term heat build up could be a problem. Far more drivers suffer toasted coils from long term heat build up than short term overpowering. IMO if the OP has to consistently push the amp hard to get adequate output he could be looking at shortened driver lifespan, perhaps drastically shortened, so the higher sensitivity of adding a second cab would be in order.

[charic]

Don't worry BillF 2nd cab is on order as soon as I can find the funds (despite the disapproving look from the mrs).

This really is more for curiosities sake

[charic]

[quote name='xgsjx' timestamp='1319201393' post='1411198']
Drop C is even better!!!

I'd like to try a bunch of 450-500w rated heads & put them one after the other through the same cab & see how each compares in Db.

Alex, I dare say you've already tried this?
[/quote]

Just the kind of experiments I enjoy, although I typically target microphones rather than bass gear

[alexclaber]

[quote name='charic' timestamp='1319201124' post='1411193']Does the fact that it is "louder than it's watts" make any kind of difference though, this is where I get confused tbh! 450 TCE watts have been proved not to be real world watts (although watts mean sod all anyway) however they reproduce a volume similar the standard output from a 450-500w head.[/quote]

They may sound as loud to many people but they don't measure as loud. I can see why people like them and I continue to recommend them to customers when that sound will suit them but having tried them myself at properly high SPL with a cab that can handle far more power without compression I can clearly hear what the processing's doing. Nice sounding and loud amp though, despite not being my bag!

[quote name='charic' timestamp='1319201124' post='1411193']The bit that is a little stuck in my head is the fact that it's recreating these kind of volume levels which surely must translate into the speakers moving the same amount as they do for a standard 450-500w head...[/quote]

No, they aren't producing the dB SPL of a more powerful amp, just as the peak dB SPL coming from an album like Californication isn't as loud as the peak dB SPL coming from Songs In The Key Of Life when both are turned up to equal loudness on your hi-fi. You can do a quick and dirty test of this by cranking up two such dissimilarly produced albums and see how much more your hi-fi woofers move on the 'quieter' album.

Regarding the thermal thing Bill, one would hope that if a cab is rated at 250W its woofers have endured the usual 1000W peak 250W average AES test for two hours. Surely it would have to be a really crazily loud and long non-stop gig for the RH450 to exceed those thermal challenges?

[LawrenceH]

[quote name='alexclaber' timestamp='1319203119' post='1411247']
Regarding the thermal thing Bill, one would hope that if a cab is rated at 250W its woofers have endured the usual 1000W peak 250W average AES test for two hours. Surely it would have to be a really crazily loud and long non-stop gig for the RH450 to exceed those thermal challenges?
[/quote]

I've seen woofers that have failed thermally when it seems hard to fathom given RMS ratings...probably because they were enclosed in a small, padded box. Porting aside, baltic birch, wool etc are rather good insulators! If given RMS specs are just based on driver ratings then they're not necessarily all that accurate in a given box.

PS I effing hate the mastering on Californication, ruined the album IMO. The Stevie, though, is lovely.

[Bill Fitzmaurice]

[quote name='alexclaber' timestamp='1319203119' post='1411247']

Regarding the thermal thing Bill, one would hope that if a cab is rated at 250W its woofers have endured the usual 1000W peak 250W average AES test for two hours. Surely it would have to be a really crazily loud and long non-stop gig for the RH450 to exceed those thermal challenges?
[/quote]
That test, as well as EIA 426a, is done with pink noise. The power density with a heavily compressed musical tone is far more stressful. I give builders maximum voltage specs for subwoofer cab/driver combinations, so that they may limit to that voltage to prevent going past xmax, not so much as to prevent mechanical damage but as to prevent long term heat build up. Eminence went through a nightmare situation with the LAB 12 driver and LabHorn, as telltale distortion when pushed beyond xmax couldn't be heard. Drivers dropped by the dozen, and almost all of them died from long term overheating even though they were seldom pushed past Pe. The problem was compounded by a driver chamber that was too small for adequate driver cooling, which was addressed with an aluminum chamber cover that doubled as a heat sink.

Edited October 21, 2011 by Bill Fitzmaurice