Calculations says I need a power amp with 250 watts for KEF R11.

[john20182050]

Calculations say I need a power amp with 250 watts for KEF R11 if I want to listen to music at 105db with some headroom. I sit about 10 feet from the speakers.
Is it possible to just use a power amp (without preamp) to connect to my receiver AVR 4400H? Do I need to buy an integrated amp or power amp + preamp to get HT bypass? If don't buy a power amp(without preamp) without HT bypass, what will be my problem?

 

[AcuDefTechGuy]

Yes, you can add an external amp to your Denon X4400H.

Do you really listen THAT LOUDLY?

 

[PENG]

View attachment 55243

Calculations say I need a power amp with 250 watts for KEF R11 if I want to listen to music at 105db with some headroom. I sit about 10 feet from the speakers.
Is it possible to just use a power amp (without preamp) to connect to my receiver AVR 4400H? Do I need to buy an integrated amp or power amp + preamp to get HT bypass? If don't buy a power amp(without preamp) without HT bypass, what will be my problem?

No unless you have another good reason, adding a power amp alone should be your best option. I have the X4400H with external amps and the sound quality is amazing. Integrated amps are for specific reasons, they are typically not the best value because they don't benefit as much from the scale of economy, and manufacturers know they can get away with a higher mark up, knowing that many so called audiophiles believe they "sound better" than most AVRs.

 

[TLS Guy]

View attachment 55243

Calculations say I need a power amp with 250 watts for KEF R11 if I want to listen to music at 105db with some headroom. I sit about 10 feet from the speakers.
Is it possible to just use a power amp (without preamp) to connect to my receiver AVR 4400H? Do I need to buy an integrated amp or power amp + preamp to get HT bypass? If don't buy a power amp(without preamp) without HT bypass, what will be my problem?

There is no 5" midrange that will take that power. The mid crosses at 400 Hz so the power to the mid would exceed 100 watts. No 5" driver will tolerate that.

If you drive those speakers to 105 db that mid will be toast I guarantee.

 

[Pogre]

Calculations say you "need" 250 watts? How loud do you "need" to listen??

 

[Pogre]

Calculations say I need a power amp with 250 watts for KEF R11 if I want to listen to music at 105db with some headroom

You do realize 105 dB is dangerously loud and will destroy your hearing, right? Lol

*Edit: And will also destroy those speakers!

 

[PENG]

There is no 5" midrange that will take that power. The mid crosses at 400 Hz so the power to the mid would exceed 100 watts. No 5" driver will tolerate that.

If you drive those speakers to 105 db that mid will be toast I guarantee.

Good point, but he may be able to use a 1 kW McIntosh to drive the R11 and I guarantee the mid range driver would not be toasted unless that 105 dB are produced by that 5" driver only and for a long enough duration. We have to assume he listens to music, stereo, not mono, and not sine wave tones.

 

[Pogre]

Good point, but he may be able to use a 1 kW McIntosh to drive the R11 and I guarantee the mid range driver would not be toasted unless that 105 dB are produced by that 5" driver only and for a long enough duration. We have to assume he listens to music, stereo, not mono, and not sine wave tones.

105 dB with some headroom tho? That's just ridiculous and literally deafening. Reference is s'posed to be 85 dB with room for 20 dB peaks and even that's too loud for any prolonged listening session.

 

[PENG]

You do realize 105 dB is dangerously loud and will destroy your hearing, right? Lol

*Edit: And will also destroy those speakers!

Will, or may?

See my counter points to TLSG..

Also, don't forget TLSG tend to under estimate the share of the woofers, he doesn't even believe in setting crossover to 80 Hz would help off loading an AVR or power amp.

 

[Pogre]

Will, or may?

See my counter points to TLSG..

May, I stand corrected sir.

I may have jumped on the bandwagon a little hastily there.

*PS, I don't think I'm jumping the gun on that volume level and damaging hearing tho!

 

[AcuDefTechGuy]

There is no 5" midrange that will take that power. The mid crosses at 400 Hz so the power to the mid would exceed 100 watts. No 5" driver will tolerate that.

If you drive those speakers to 105 db that mid will be toast I guarantee.

Maybe it's okay if that "105dB" is coming from the ENTIRE SYTEM (all speakers + Subwoofers).

But not a good idea for ONE speaker to play 105dB.

 

[Pogre]

But not a good idea for ONE speaker to play 105dB.

Or to listen at 105 dB period, if you value your hearing.

 

[PENG]

Maybe it's okay if that "105dB" is coming from the ENTIRE SYTEM (all speakers + Subwoofers).

But not a good idea for ONE speaker to play 105dB.

Exactly my point, thank you.

 

[TLS Guy]

Will, or may?

See my counter points to TLSG..

Also, don't forget TLSG tend to under estimate the share of the woofers, he doesn't even believe in setting crossover to 80 Hz would help off loading an AVR or power amp.

No, you underestimate the power required above 400 Hz. That IS the lions share of the spectrum of most instruments. Insufficient power and resources in the region is a major failing of most speakers. Dynamic compression is a huge problem of three way designs. 400 Hz to 4 KHz is a major power band. For most midrange drivers, two are required and not one!

 

[AcuDefTechGuy]

Or to listen at 105 dB period, if you value your hearing.

Yeah, that's why I asked him, "Do you really listen THAT LOUDLY?"

I can see the ENTIRE SYSTEM, especially when the SUBS are firing away during short loud action scenes, to reach 105dB.

I think I have measured my ENTIRE system to be 105dB with all the subs firing away for a relatively short period of time.

 

[Pogre]

Yeah, that's why I asked him, "Do you really listen THAT LOUDLY?"

I can see the ENTIRE SYSTEM, especially when the SUBS are firing away during short loud action scenes, to reach 105dB.

I think I have measured my ENTIRE system to be 105dB with all the subs firing away for a relatively short period of time.

Yeah, 105 dB peaks is one thing. Listening at 105 dB and expecting to need headroom on top of that is just... literally, dangerously a recipe for permanent hearing loss!

 

[AcuDefTechGuy]

Will, or may?

See my counter points to TLSG..

Also, don't forget TLSG tend to under estimate the share of the woofers, he doesn't even believe in setting crossover to 80 Hz would help off loading an AVR or power amp.

I think the KEF R11 will be JUST FINE with a 200/250WPC amp.

A friend of mine has the KEF R11 and the ATI 200WPC amp. He plays very loudly.

 

[Pogre]

No, you underestimate the power required above 400 Hz. That IS the lions share of the spectrum of most instruments. Insufficient power and resources in the region is a major failing of most speakers. Dynamic compression is a huge problem of three way designs. 400 Hz to 4 KHz is a major power band. For most midrange drivers, two are required and not one!

Well, like ADTG points out the system as a whole can hit those volumes when you count the other drivers and subs. I'm switching direction and pointing out that's far too loud as a baseline to be listening to anything.

 

[PENG]

May, I stand corrected sir.

I may have jumped on the bandwagon a little hastily there.

*PS, I don't think I'm jumping the gun on that volume level and damaging hearing tho!

Right! That's why I didn't fix the hearing part for you.

On the speaker damage part, keep in mind the OP also did not say he wants one speaker to produce 105 dB, let alone one driver. In stereo, most of time there will be two 5" driver is to produce 105 dB peak, so on average each will only have to produce 102 dB, and power required will be cut to half, and will also be cut by another half in terms of average power.

So again
Average power = 0.5 peak power, or avg power to peak power ratio = - 3 dB
Two drivers would produce 3 dB more SPL than one driver would, assuming both gets the same signal obviously.

 

[Pogre]

I will say, if op wants a powerful amp then I say just get one. It's certainly not necessary, but that hasn't stopped most of us from getting one. There's no need to justify it by claiming ridiculous listening levels tho.