Power amp specification vs speaker specification

[laidick]

I have doubt on how to judge if a power amp is capable to drive a speaker by just looking in the specification.

I try not to put the product name but just the spec here, hope if I could get some light from the expert here.

Power amp:
TECHNICAL SPECIFICATIONS
Stereo True Dual Mono Design
Distortion: THD+N – – 0.001 % 20Hz
Frequency Response: 0 – 50k Hz +0/-3dB
Low Distortion: THD+N – – 0.001 % 20Hz
High Input Impedance 47K
Sound to noise ratio: 135db
26 dB Gain
Ultra High Damping Factor
Power rating (channel): 550W @ 2ohm | 700W @ 4ohm | 400W @ 8ohm

Speaker:
SPECIFICATIONS
Type: 3 ½-Way, bass reflex
Crossover frequency: 140 | 360 | 2700 Hz
Frequency range (IEC 268-5): 28 – 50000 Hz
Sensitivity: 89 dB at 2,83 V/m
Suitable for amplifiers from… to: 4 – 8 Ω
Recommended amplifier power: 40 – 450 W/channel
Nominal | Peak power handling: 200 W | 280 W
Nominal | Minimum impedance: 4 Ω | 3,4 Ω at 105 Hz

In order to make the judgment , is there anything else from technical perspective we need to extract from the product?

Thanks.

 

[SIY]

In order to make the judgment , is there anything else from technical perspective we need to extract from the product?

Yes, actual measurements with conditions specified. Most of what's there is fairly useless.

Power amp:
TECHNICAL SPECIFICATIONS
Stereo True Dual Mono Design- Marketing speak and irrelevant
Distortion: THD+N – – 0.001 % 20Hz -At what power? What load? And how does that change with frequency?
Frequency Response: 0 – 50k Hz +0/-3dB- At what power? What load? And -3dB where?
Low Distortion: THD+N – – 0.001 % 20Hz- At what power? What load? And how does that change with frequency?
High Input Impedance 47K
Sound to noise ratio: 135db- What bandwidth? What reference level?
26 dB Gain
Ultra High Damping Factor- Numbers, please.
Power rating (channel): 550W @ 2ohm | 700W @ 4ohm | 400W @ 8ohm -At what frequencies? For how long? Continuous? Pulse?

SPECIFICATIONS
Type: 3 ½-Way, bass reflex
Crossover frequency: 140 | 360 | 2700 Hz- Meaningless and useless to the consumer
Frequency range (IEC 268-5): 28 – 50000 Hz- Measured where in space? And the IEC test signal described cannot be used to show a frequency response in that range, it's pink noise band-limited to 40-5000 Hz. And how does that vary horizontally and vertically?
Sensitivity: 89 dB at 2,83 V/m- With what test signal? At what frequencies?
Suitable for amplifiers from… to: 4 – 8 Ω Garbled
Recommended amplifier power: 40 – 450 W/channel
Nominal | Peak power handling: 200 W | 280 W- At what frequencies with what signal and for how long?
Nominal | Minimum impedance: 4 Ω | 3,4 Ω at 105 Hz - OK, nice to have a minimum, but what does the curve look like?

 

[laidick]

Yes, actual measurements with conditions specified. Most of what's there is fairly useless.

Power amp:
TECHNICAL SPECIFICATIONS
Stereo True Dual Mono Design- Marketing speak and irrelevant
Distortion: THD+N – – 0.001 % 20Hz -At what power? What load? And how does that change with frequency?
Frequency Response: 0 – 50k Hz +0/-3dB- At what power? What load? And -3dB where?
Low Distortion: THD+N – – 0.001 % 20Hz- At what power? What load? And how does that change with frequency?
High Input Impedance 47K
Sound to noise ratio: 135db- What bandwidth? What reference level?
26 dB Gain
Ultra High Damping Factor- Numbers, please.
Power rating (channel): 550W @ 2ohm | 700W @ 4ohm | 400W @ 8ohm -At what frequencies? For how long? Continuous? Pulse?

SPECIFICATIONS
Type: 3 ½-Way, bass reflex
Crossover frequency: 140 | 360 | 2700 Hz- Meaningless and useless to the consumer
Frequency range (IEC 268-5): 28 – 50000 Hz- Measured where in space? And the IEC test signal described cannot be used to show a frequency response in that range, it's pink noise band-limited to 40-5000 Hz. And how does that vary horizontally and vertically?
Sensitivity: 89 dB at 2,83 V/m- With what test signal? At what frequencies?
Suitable for amplifiers from… to: 4 – 8 Ω Garbled
Recommended amplifier power: 40 – 450 W/channel
Nominal | Peak power handling: 200 W | 280 W- At what frequencies with what signal and for how long?
Nominal | Minimum impedance: 4 Ω | 3,4 Ω at 105 Hz - OK, nice to have a minimum, but what does the curve look like?

All great points.
However, is that the grey area the manufacturer usually hide the information in this industry? Or if there is a 'standard' that the manufacturer doesn't put it explicitly in the specification?

Every seller wants to market the product as great as possible, but how could customer be treated fairly in this game ?

 

[SIY]

Take a look at the attachment from AP. It's a good start. And ignore manufacturer specs that are incomplete- if they won't provide useful measurements (and most don't), look for them being done by independent sources like ASR or AudioXpress. Stereophile's measurements are also pretty reliable, as long as you ignore the dribblings from the reviewer and the little dance at the end by Atkinson.

 

[Krunok]

I have doubt on how to judge if a power amp is capable to drive a speaker by just looking in the specification.

I try not to put the product name but just the spec here, hope if I could get some light from the expert here.

Power amp:
TECHNICAL SPECIFICATIONS
Stereo True Dual Mono Design
Distortion: THD+N – – 0.001 % 20Hz
Frequency Response: 0 – 50k Hz +0/-3dB
Low Distortion: THD+N – – 0.001 % 20Hz
High Input Impedance 47K
Sound to noise ratio: 135db
26 dB Gain
Ultra High Damping Factor
Power rating (channel): 550W @ 2ohm | 700W @ 4ohm | 400W @ 8ohm

Speaker:
SPECIFICATIONS
Type: 3 ½-Way, bass reflex
Crossover frequency: 140 | 360 | 2700 Hz
Frequency range (IEC 268-5): 28 – 50000 Hz
Sensitivity: 89 dB at 2,83 V/m
Suitable for amplifiers from… to: 4 – 8 Ω
Recommended amplifier power: 40 – 450 W/channel
Nominal | Peak power handling: 200 W | 280 W
Nominal | Minimum impedance: 4 Ω | 3,4 Ω at 105 Hz

In order to make the judgment , is there anything else from technical perspective we need to extract from the product?

Thanks.

Well, as @SIY explained, manufacturers pretty much always give vague and unprecised numbers. However, the thing I first look at when judging amp is if power supply can actually provide coninuous supply to declared power rating figures, so I suggest you check power consumption figure and if it exceeds those 700W per channel of declared power there is a chance you are indeed dealing with a decently designed amp. This means that power consumption figure should be at least 1500W.

 

[pozz]

All great points.
However, is that the grey area the manufacturer usually hide the information in this industry? Or if there is a 'standard' that the manufacturer doesn't put it explicitly in the specification?

Every seller wants to market the product as great as possible, but how could customer be treated fairly in this game ?

Manufacturer info is largely inaccessible unless they make it part of their business to disclose it.

And unfortunately there is no getting around the fact that the consumer is treated very poorly.

It's pretty frustrating and it makes research impossible unless you stumble on a technically knowledgable person that goes out of their way to test and review the product.

 

[laidick]

Manufacturer info is largely inaccessible unless they make it part of their business to disclose it.

And unfortunately there is no getting around the fact that the consumer is treated very poorly.

It's pretty frustrating and it makes research impossible unless you stumble on a technically knowledgable person that goes out of their way to test and review the product.

And probably that's why all we are here at ASR

 

[Victoria]

Manufacturer info is largely inaccessible unless they make it part of their business to disclose it.

And unfortunately there is no getting around the fact that the consumer is treated very poorly.

It's pretty frustrating and it makes research impossible unless you stumble on a technically knowledgable person that goes out of their way to test and review the product.

And this is actually one of the super big reasons I love Class-D amplifiers so much!

Since a very large portion of them utilise amplification modules which have been acquired from proper engineering firms who are in the business of dealing predominantly with other companies or professional users who demand detailed measurements and datasheets; so even if the manufacturer of the amplifier doesn't provide proper specifications, it's extremely easy to find out what modules they're using (mostly from inevitable teardowns of the product made accessible online) and to subsequently pull the datasheets from the original manufacturer of the amplification module. Just take a look at how many dozens of pages the typical Hypex, ICEpower, or Pascal -- just to name a few -- datasheets are.

Sure, some manufacturers will still meddle around with the modules or buffers or whatever else thinking they know better than the designers of the original modules -- and who knows, maybe they do, but maybe they don't (especially if they don't have the data to back up their claims) -- at least however it usually still gives you a decent idea with regards to how much power you have available. And as I always like to say: MORE POWER!~

Not to mention you'll also rest easy knowing that a good chunk of the amplifier is electrically safe.

 

[BillG]

Just take a look at how many dozens of pages the typical Hypex, ICEpower

Yes, I've a good deal of confidence in amplifiers built around these two manufacturers modules as well; Hypex being top tier to me, and numerous pro audio professionals, and ICEpower coming in second to that...

 

[edechamps]

Frequency range (IEC 268-5): 28 – 50000 Hz- the IEC test signal described cannot be used to show a frequency response in that range, it's pink noise band-limited to 40-5000 Hz.

IEC 268-5 is not just a test signal, it's a 58-page document that also describes a method of measurement for effective frequency range (IEC 60268-5:2007 section 21.2, page 25), which uses sines. That's most likely what they meant here.

 

[laidick]

So, what is the relation between speaker headroom and amplifier peak power?

Say, for example, I have a speaker 89db sensitivity ,4ohm, listening 3 meters apart, with 75db average, and 30db headroom (assume 105db peak).
The power requirement will be 358w peak, and normally use less than 1w...

How does speaker impedance impact in above calculation? (4ohm seems not anywhere in the formula)

Ideally, amplifier like AHB2 should fit the purpose.
Why sometimes people need an amplifier of 300w continuous and 1200w peak? Is there any benefit for such ?

Thanks.

 

[Blumlein 88]

So, what is the relation between speaker headroom and amplifier peak power?

Say, for example, I have a speaker 89db sensitivity ,4ohm, listening 3 meters apart, with 75db average, and 30db headroom (assume 105db peak).
The power requirement will be 358w peak, and normally use less than 1w...

How does speaker impedance impact in above calculation? (4ohm seems not anywhere in the formula)

Ideally, amplifier like AHB2 should fit the purpose.
Why sometimes people need an amplifier of 300w continuous and 1200w peak? Is there any benefit for such ?

Thanks.

How did you come up with 358 watts peak?

I'd make it more like 80 watts for 105 db output, and that is with some simplifying assumptions.

Here is a simple explanation of the IEC power rating guidelines.
https://www.jblpro.com/pub/technote/spkpwfaq.pdf

Notice they suggest the amp have twice the power needed for speaker peaks. So now you might be up to 160 watts for your example speaker.

There are many details as to why suggested power isn't precise. There are no 4 ohm or 8 ohm speakers. Magnepans come close to 4 ohms resistive. Most have lots of inductance and capacitance mixed in giving a roller coaster graph of impedance vs frequency. So maybe your speaker has a minimum impedance and phase angle that might require much additional current. Could easily be double or more theoretical values. Then maybe you aren't wrong to move up to 320 watts. Plus if you don't push your speaker to its very limits, then maybe even 40 watts is enough almost all the time. So you see things like 40-320 wpc recommended.

As for needing 300 wpc or more some speakers can require that to reach peak output cleanly. If your example speakers were only 86 db sensitive (which is close to average btw) you need to double all the numbers again.

 

[laidick]

How did you come up with 358 watts peak?

I'd make it more like 80 watts for 105 db output, and that is with some simplifying assumptions.

Here is a simple explanation of the IEC power rating guidelines.
https://www.jblpro.com/pub/technote/spkpwfaq.pdf

Notice they suggest the amp have twice the power needed for speaker peaks. So now you might be up to 160 watts for your example speaker.

There are many details as to why suggested power isn't precise. There are no 4 ohm or 8 ohm speakers. Magnepans come close to 4 ohms resistive. Most have lots of inductance and capacitance mixed in giving a roller coaster graph of impedance vs frequency. So maybe your speaker has a minimum impedance and phase angle that might require much additional current. Could easily be double or more theoretical values. Then maybe you aren't wrong to move up to 320 watts. Plus if you don't push your speaker to its very limits, then maybe even 40 watts is enough almost all the time. So you see things like 40-320 wpc recommended.

As for needing 300 wpc or more some speakers can require that to reach peak output cleanly. If your example speakers were only 86 db sensitive (which is close to average btw) you need to double all the numbers again.

I simply use the crown website calculator to do it.

 

[cistercian]

I trust the engineers at Harmon/crown/JBL. Use their calculator.