AVR Power Ratings & How to know when I need an external amp?

[Barron]

Alright Audiophiles hit me with some math formulas please and how to peel out the variables from OEM sites I would use to calculate the formulas. That way I can optimize my set up.

I watched this video by Gene DellaSala about "specmanship" https://www.audioholics.com/audio-amplifier/ftc-consumer-audio and I came out with a couple questions. First of all really insightful video which is why I love exploring this website for material and education.

Running
Yamaha RX-A1080 (OEM Site

• Rated Output Power (1kHz, 2ch driven) 120 W (8 ohms, 0.9% THD)
• Rated Output Power 20Hz-20kHz, 2ch driven) 110 W (8 ohms, 0.06% THD)
• Maximum Effective Output Power (1kHz, 1ch driven) (JEITA) 165 W (8 ohms, 10% THD)
• Dynamic Power / Ch (Front L/R, 8/6/4/2 ohms) 135 / 165 / 210 / 280 W

Klipsch RP-8000F
Klipsch RP-404C
Monoprice Monolith 10"
(soon two rear and two ceiling speakers)

Questions:
1. First of all what is full range and how do I make sure my speakers (when I have them all) are operating at full range vs. speaker mode (just two fronts)? As simple as plugging in multiple channels or do I need to learn my AVR capabilities more?
2. When does the Yamaha RX-A1080 start clipping? {maybe the OEM site already gave me that answer?}
3. How do I determine when my speakers will start going flat once clipping begins?
4. What are the formulas to determine if I need 1 or 2 external amps? For example do I need an external Amp for my Klipsch RP-8000Fs? What about for my subwoofer?

Thanks!

 

[Leemix]

Alright Audiophiles hit me with some math formulas please and how to peel out the variables from OEM sites I would use to calculate the formulas. That way I can optimize my set up.

I watched this video by Gene DellaSala about "specmanship" https://www.audioholics.com/audio-amplifier/ftc-consumer-audio and I came out with a couple questions. First of all really insightful video which is why I love exploring this website for material and education.

Running
Yamaha RX-A1080 (OEM Site

• Rated Output Power (1kHz, 2ch driven) 120 W (8 ohms, 0.9% THD)
• Rated Output Power 20Hz-20kHz, 2ch driven) 110 W (8 ohms, 0.06% THD)
• Maximum Effective Output Power (1kHz, 1ch driven) (JEITA) 165 W (8 ohms, 10% THD)
• Dynamic Power / Ch (Front L/R, 8/6/4/2 ohms) 135 / 165 / 210 / 280 W

Klipsch RP-8000F
Klipsch RP-404C
Monoprice Monolith 10"
(soon two rear and two ceiling speakers)

Questions:
1. First of all what is full range and how do I make sure my speakers (when I have them all) are operating at full range vs. speaker mode (just two fronts)? As simple as plugging in multiple channels or do I need to learn my AVR capabilities more?
2. When does the Yamaha RX-A1080 start clipping? {maybe the OEM site already gave me that answer?}
3. How do I determine when my speakers will start going flat once clipping begins?
4. What are the formulas to determine if I need 1 or 2 external amps? For example do I need an external Amp for my Klipsch RP-8000Fs? What about for my subwoofer?

Thanks!

1. Full range just means without bass management, usually you want speakers set to small wi5 a crossover to let the sub or subs do the low frequency work but your sub is probably by far the weak link.
2ch vs multichannel depends on the source and what you prefer. Stereo, direct (or similar, unsure what name yamaha use) just use 2 speakers, direct without sub (probably) stereo can use sub if main speakers set to small. For multichannel it usually defaults to the right mode or if you want multi speaker from just 2 channel source then use different sound modes like multi channel stereo or such.

2. That depends on speakers efficiency (yours are efficient), distance and volume you listen to. When clipping begins it usually starts to sound harsh/compressed/noisy.

3. Not sure what you mean but might be the same as i wrote for point 2.

4. I dont have any links handy, many posts with those on this forum and others probably do. You likly dont really need it according to the formulas.
Your sub is powered, it cant be connected to an external amplifier in addition. It gets a line level signal from the reciever that is amplified by the subs own internal amplifier. The sub you have is probably the weakest link in your system if thats what you are looking for.

Remember placement is very important for all speakers and the sub. The room is a big part of any systems sound.


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[Barron]

Thanks for the reply. Room is about ~1600ft^3.

I'll keep digging around for the formula's and OEM variables I'm looking for.
Sounds like I need to beef up my Sub. Since I haven't experienced many products out there I think doing the math on paper will show me what to buy in the future.
I was going to buy the RSL Speedwoofer 10" but one of our friends here suggested going with SVS, Monoprice, or HSU to go with my RP-8000F's. I'll try the monoprice and return it if need be. I'm a bassaholic so I do want a sub that's not the weak link. I went with this one because it was medium room rated and I didn't think I wanted to completely blow my windows out with a large room sub.

1. Thanks for giving me something new to research. Crossovers and how to use them!
2 & 3. My intention here was to learn what the Knee is on the Yamaha. And separately what the max Vrms (I think) the Speakers can handle. Mainly trying to learn how to read and understand specs better. The graph, formula/variables in the video I tagged is what my mind see's now when I see AVR specs. Except now of these 4 which one is the "knee" if one is? And pretty much how do you or someone else read these?

• Rated Output Power (1kHz, 2ch driven) 120 W (8 ohms, 0.9% THD)
• Rated Output Power 20Hz-20kHz, 2ch driven) 110 W (8 ohms, 0.06% THD)
• Maximum Effective Output Power (1kHz, 1ch driven) (JEITA) 165 W (8 ohms, 10% THD)
• Dynamic Power / Ch (Front L/R, 8/6/4/2 ohms) 135 / 165 / 210 / 280 W

4. Thanks I was wondering how the internal amp would stack up with an external one. Now I know it cannot!

 

[PENG]

Thanks for the reply. Room is about ~1600ft^3.

Given that room size, you probably sit no further than 11 ft away from your RP-8000F and RP-404C. That means even if you de-rate your speakers by 6 dB in sensitivity just to be super conservative, you can hit reference level with the RX-A1080.
https://myhometheater.homestead.com/splcalculator.html

I'll keep digging around for the formula's and OEM variables I'm looking for.

Formula to calculate what? Regardless, the linked below should take you to sites where you can find all sorts of audio related formulae:

http://www.sengpielaudio.com/calculator-gainloss.htm
http://www.sengpielaudio.com/calculator-ohm.htm
http://www.sengpielaudio.com/calculator-FactorRatioLevelDecibel.htm
http://www.acousticfrontiers.com/2013322spl-calculator/ (there is a link to the calculator)

If you have trouble understanding some of the specific ones, just ask, I'll be happy to help. You should have no trouble if you have good knowledge in physics and/or EE and are familiar with the hifi audio related terminologies.

2 & 3. My intention here was to learn what the Knee is on the Yamaha. And separately what the max Vrms (I think) the Speakers can handle. Mainly trying to learn how to read and understand specs better. The graph, formula/variables in the video I tagged is what my mind see's now when I see AVR specs. Except now of these 4 which one is the "knee" if one is? And pretty much how do you or someone else read these?

• Rated Output Power (1kHz, 2ch driven) 120 W (8 ohms, 0.9% THD)
• Rated Output Power 20Hz-20kHz, 2ch driven) 110 W (8 ohms, 0.06% THD)
• Maximum Effective Output Power (1kHz, 1ch driven) (JEITA) 165 W (8 ohms, 10% THD)
• Dynamic Power / Ch (Front L/R, 8/6/4/2 ohms) 135 / 165 / 210 / 280 W

To see the knee point, you should see the lab measurements such as the ones (just examples) below:
Unfortunately, it would be tough to find such graphs for the RX-A1080

https://www.soundandvision.com/content/yamaha-rx-a1020-av-receiver-ht-labs-measures

https://www.audioholics.com/av-receiver-reviews/yamaha-rx-a860/measurements

My best guess for the "knee point" for the RX-A1080 would be between 110 and 120 W, 20-20 kHz, 0.1% THD

4. Thanks I was wondering how the internal amp would stack up with an external one. Now I know it cannot!

It may depend on the external amp you are comparing to. In my opinion though, the internal amps of the RX-A1080 should stack up very well against any external amps if used well below it's rated output.

 

[Leemix]

PENG did a nice reply on power so ill only make a note about subs. Its the settings and volume you play at that determine if the windows blow out or not (to some extent, some subs just wont be able to). Many belive that a big sub or multiple subs will give a lot more bass but thats not neccessarily true. If set up right and not boosted by a lot(like many bass heads do) they wont shake the house unless you play loud. It/they will play effortlessly with control while a single small sub will struggle while trying to do the exact same job (and volume) even at moderate volumes.


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[PENG]

PENG did a nice reply on power so ill only make a note about subs. Its the settings and volume you play at that determine if the windows blow out or not (to some extent, some subs just wont be able to). Many belive that a big sub or multiple subs will give a lot more bass but thats not neccessarily true. If set up right and not boosted by a lot(like many bass heads do) they wont shake the house unless you play loud. It/they will play effortlessly with control while a single small sub will struggle while trying to do the exact same job (and volume) even at moderate volumes.


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Thanks, by the way, I think his room is small enough. The 10" Monolith should be more than adequate even for a bass head.

 

[Leemix]

Thanks, by the way, I think his room is small enough. The 10" Monolith should be more than adequate even for a bass head.

If so then he should be good already.

(Feet, horizontal or cubed is not my friend, we use the metric system where i live so difficult to quickly estimate size or room for me. I assumed a somewhat spacious room especially with quite large klipsch speakers)


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[Barron]

Thank you both! Digging into all of this information PENG sent now.

 

[Andrein]

I have almost identical room. A1070, 9ft to LP. Getting ref level + 20db with my 2 svs sb2000. Which are small sealed subs. Which means for your room you can use almost any subs to get HT experience.

 

[PENG]

If so then he should be good already.

(Feet, horizontal or cubed is not my friend, we use the metric system where i live so difficult to quickly estimate size or room for me. I assumed a somewhat spacious room especially with quite large klipsch speakers)


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Yeah he used that ^3 symbol that means to the power 3, as he said "Room is about ~1600ft^3 ". So that is 1,600 cubic ft.

In the the AH review on the 10" and 12" subs, the reviewer said:

"Both these subs have enough output to meet Audioholic’s Bassaholic ‘Large’ room rating, with the 10” THX Select just squeaking by to capture that rating and the 12” THX Ultra very comfortably meeting that room rating. The Bassaholic ‘large’ room rating means that these subs should be suitable for a room in size from 3,000 cubic feet to 5,000 cubic feet. While the 10” THX Select does technically qualify for that rating, I think it would get overwhelmed in a 5,000 cubic foot room."

https://www.audioholics.com/subwoofer-reviews/monolith-10201d-12/conclusion

Obviously it won't hurt to add a second 10".

 

[Barron]

I have almost identical room. A1070, 9ft to LP. Getting ref level + 20db with my 2 svs sb2000. Which are small sealed subs. Which means for your room you can use almost any subs to get HT experience.

I've got another monolith in the cart. I'm thinking I need to wait a few months before I spend more money, or maybe one more month, or a week. Thanks for the input guys!

 

[markw]

you can crunch numbers all you want but until you have the speakers and hook them up, you're just engaging in mental masturbation. You just might find that those speakers will play stupid loud and clean with just that receiver, particularly since you're adding sub woofers into the mix.

Of course. if you just want an external amp to have an external amp, that's OK too,

 

[ryanosaur]

I've got another monolith in the cart. I'm thinking I need to wait a few months before I spend more money, or maybe one more month, or a week. Thanks for the input guys!

Unless you're waiting for a sale... ...do it! They do go on sale from time to time... but Monoprice seems to be a little random in that practice.

Just a side note re: the elusive Full Range speaker... Finding a speaker that is capable down to 20Hz is pretty challenging. It seems that at almost any price bracket now, they don't really exist.
(They can and do... but along with usually being expensive, they also are very large due to the necessities of physics. Consider that the Hsu VTF2 Sub which is capable of a low end extension between 18-22Hz is roughly 2.75'3 internal volume (about 77 liters). Following is a link for a very cool looking DIY speaker that might not actually be full range... I'm estimating maybe 25Hz @ F3. But as a point of comparison, consider that the woofer cabinet alone has a volume of 60 liters, and the cabinet overall is about 43.5"H x 13.75"W x 17.75"D: HUGE by modern speaker standards.)
http://www.troelsgravesen.dk/Illuminator-4.htm
Regardless, thought this to be an interesting addition to the conversation, considering part of your first point stated above... (and the ongoing conversation in other threads about whether DefTech speakers, for example, are actually full range).

 

[lovinthehd]

https://www.audioholics.com/home-theater-connection/connecting-an-external-amp-to-a-receiver

 

[Barron]

you can crunch numbers all you want but until you have the speakers and hook them up, you're just engaging in mental masturbation. You just might find that those speakers will play stupid loud and clean with just that receiver, particularly since you're adding sub woofers into the mix.

Of course. if you just want an external amp to have an external amp, that's OK too,

You caught me! My mind is turned on by the physics in audio. I keep recalling memories from taking vibrations in college and know that a lot of these terms I see use are derived from some sort of sinusoidal equation. I'll probably pull my old notebook out and start another forum with that stuff just for fun.

And you caught me again so get out of my head. Yes I want an external amp to have an external amp! I also and going to run a zone 2, maybe that's justified.