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Author Topic: yet another way to describe amp power  (Read 3418 times)

Keith Broughton

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yet another way to describe amp power
« on: July 02, 2017, 11:55:48 am »

Recently found in amplifier description...

Quote
Unusually these are not, ‘transient’, ‘burst’ or ‘peak’ power figures, they are the power levels that are delivered by both channels simultaneously even when driven with the same dense program material.
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Tim Weaver

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Re: yet another way to describe amp power
« Reply #1 on: July 02, 2017, 12:16:41 pm »

Wut?



Why is it a problem to just say XX watts at X ohms with X% distortion?
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Ivan Beaver

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Re: yet another way to describe amp power
« Reply #2 on: July 02, 2017, 12:39:24 pm »

Recently found in amplifier description...
Is this a review or in a spec?

Either way, it needs a lot more explanation
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Ivan Beaver
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Keith Broughton

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Re: yet another way to describe amp power
« Reply #3 on: July 02, 2017, 01:03:12 pm »

Is this a review or in a spec?

Either way, it needs a lot more explanation
This is from a description of a power amplifier on the product page of an amplifier manufacturer.
They use it on each of their model pages.
A bit of WTF from my POV!
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David Sturzenbecher

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Re: yet another way to describe amp power
« Reply #4 on: July 02, 2017, 01:16:24 pm »

Recently found in amplifier description...

Just cut to the chase.

http://linea-research.co.uk/44c-series/

Weren't these the same guys that gave the confusing specs that included crest factor into some other manufactures OEM amp?
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John Roberts {JR}

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Re: yet another way to describe amp power
« Reply #5 on: July 02, 2017, 02:15:29 pm »

It seems I have been writing about this subject a very long time. No not specmanship, but the difficulty in coming up with meaningful power duty cycle specs for use in live sound reinforcement.

Back last century, because consumers rewarded them for it, amp makers stopped designing continuous duty (24x7)  amplifiers and sold amps that made significantly more power for significantly less time. While extremely short term burst power could be abused, the market place would sort out what amps are wimps soon enough.

Marketing copy is rarely written by engineers and in this case it probably wouldn't help because AFAIK there is no concise spec that is meaningful across multiple genres and applications, and many have tried. Back in the 70's the hifi industry proposed a dynamic headroom spec and that kind of worked where everybody was running amps full range into modest (one box per channel) loads, playing pre-recorded music. In live sound the loading is all over the place and playback bandwidths too.

I wouldn't lose too much sleep, or read too much into these latest adventures in copywriting.

JR
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Roland Clarke

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Re: yet another way to describe amp power
« Reply #6 on: July 02, 2017, 03:33:24 pm »

They are a good product, slightly surprised that Ivan wasn't aware of their techno speak!
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Ivan Beaver

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Re: yet another way to describe amp power
« Reply #7 on: July 02, 2017, 06:46:14 pm »

They are a good product, slightly surprised that Ivan wasn't aware of their techno speak!
I generally don't read the "marketing speak".

But you can find the same sort of "what did they say/mean?" at all levels of products.

I especially love it when they come up with a new name for very common items.  Such as "Transportation assisting devices built in"  ie handles.  (I just made that up)
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Eric Dodson

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Re: yet another way to describe amp power
« Reply #8 on: July 02, 2017, 09:59:55 pm »

I generally don't read the "marketing speak".

But you can find the same sort of "what did they say/mean?" at all levels of products.

I especially love it when they come up with a new name for very common items.  Such as "Transportation assisting devices built in"  ie handles.  (I just made that up)
I like to clarify to a DJ when they brag how many watts their speaker's can handle......
"The wattage rating of a speaker doesn't tell you how loud it gets, all its telling you is what it takes to blow it up!"
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Chris Grimshaw

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Re: yet another way to describe amp power
« Reply #9 on: July 03, 2017, 03:38:30 am »

Recently found in amplifier description...

Sounds like a "pink noise, both channels driven" rating.

Chris
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Keith Broughton

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Re: yet another way to describe amp power
« Reply #10 on: July 03, 2017, 06:55:34 am »

The amp worked just fine and I think it's a good product but could not help sharing the "techno babble" for entertainment purposes :-)
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Brian Jojade

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Re: yet another way to describe amp power
« Reply #11 on: July 03, 2017, 03:40:37 pm »

Wut?



Why is it a problem to just say XX watts at X ohms with X% distortion?

Because the marketing department found out that you can get an amp to deliver a much higher number of watts, if even for an extremely brief, unusable period.  Bigger number = better marketing.

Also, the number of watts an amp can deliver will depend on the frequency that you're working with.  Again, some companies will pick the frequency that gives the biggest number to make their amp look better, even if that frequency is not the way the amp would be used.

So, unless there's an absolute standard that every manufacturer followed, just saying XX watts at X ohms with X% distortion will not give you an accurate picture to compare amps.
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John Roberts {JR}

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Re: yet another way to describe amp power
« Reply #12 on: July 03, 2017, 04:54:22 pm »

Because the marketing department found out that you can get an amp to deliver a much higher number of watts, if even for an extremely brief, unusable period.  Bigger number = better marketing.
I think the customers discovered it first by loading down 4 ohm amps to 2 ohms and discovering how smart they (thought they) were.  :o
Quote
Also, the number of watts an amp can deliver will depend on the frequency that you're working with.
Generally solid state amps make the same max power at all frequencies, but there can be a subtle difference in clipping power during continuous sinewave testing, for sine waves that are lower frequency that the PS refresh rate (120Hz). When testing at significantly higher sine wave frequencies than the PS charging rate, the draw is roughly 50% from each rail, but at lower frequencies the draw can be effectively from only one rail at a time (for 2x the capacitor sag). Increasing the size of the reservoir cap, a cost in power amps can mitigate this rail sag.
Quote
Again, some companies will pick the frequency that gives the biggest number to make their amp look better, even if that frequency is not the way the amp would be used.
A tell for amps with marginal reservoir cap size is higher rated output power at 1kHz than 20-20kHz (for same distortion, but they rarely rate them apples to apples). Music is not generally continuous sine waves, so don't expect a huge real world difference from oversized PS caps.
Quote
So, unless there's an absolute standard that every manufacturer followed, just saying XX watts at X ohms with X% distortion will not give you an accurate picture to compare amps.
In life we don't always get neat answers... I used to be product manager for power amps, so my day job was writing such specs.. I believe most companies try to be honest, but customers do reward specmanship (unfortunately).

JR
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Re: yet another way to describe amp power
« Reply #12 on: July 03, 2017, 04:54:22 pm »


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