Amplifier + speaker pairing, have I messed up?

[foamy]

Hi everyone! I've recently made a new purchase as my entry into the Hi-Fi ecosystem. I'm still awaiting the order to be delivered but am having some concerns about if I've made a huge mistake with the wattage pairing of amplifier and speakers. Some experienced advice would be much appreciated.

What I've purchased are an Onkyo A-9110 amplifier and Triangle Borea BR02 speakers. Specifications are as follows:

Onkyo A-9110: 50 W @ 4 Ohm/30 W @ 8 Ohm
Triangle BR02: 89 dB / 80 W(RMS) / 8 Ohm(Nominal)

The logic I applied to the pairing was based on attempted normalisation of speaker specifications. I did some googling and collected speaker pairing recommendations for the Onkyo A-9110 from around the web. Here are the results:

Mission LX-2: 85 dB / 80 W(RMS) / 6 Ohm(Nominal) [link]
Monitor Bronze BX5: 90 dB / 120 W(RMS) / 30-120 W(Recommended) / 8 Ohms(Nominal) [link]
Monitor 50: 87 dB / 70 W(RMS) / 15-70 W(Recommended) / 8 Ohm(Nominal) [link]
Monitor Bronze 2: 90 dB / 100 W(RMS) / 30-100 W(Recommended) / 8 Ohms(Nominal)
DALI Spektor 2: 84.5 dB / 25-100 W(Recommended) / 6 Ohms(Nominal)
Polk T50: 90 dB / 150 W(Maximum) / 8 Ohm(Nominal) [link]
KEF Q150: 86 dB / 10-100 W(Recommended) / 8 Ohm(Nominal) [link]

Attempted normalisation of values below. Where a min-max range is provided, I got a percentage, ignoring the sometimes RMS and sometimes maximum, because both were rarely provided. Where only an RMS or maximum is provided I took the average of ~25%, (excluding the KEF Q150 as it's range is very wide and so I didn't want to take the chance).

Mission LX-2: @25% => 20-80 W(RMS)
Monitor Bronze BX5: 25%
Monitor 50: 21.4%
Monitor Bronze 2: 30%
DALI Spektor 2: 25%
Polk T50: @25% => 38-150 W(Maximum)
KEF Q150: 10%

With the above considerations and the available specs of the Triangle Borea BR02 speakers I came to the following:

Triangle Borea BR02: @25% => 20-80 W(Recommended)

Considering the above, I'm assuming that the Triangle Borea BR02 can be powered within the range of 20-80 W @ 8 Ohms. The Onkyo A-9110 provides 30 W @ 8 Ohm.
Is this reasonable to consider or have I made a big mistake?

Thanks in advance for taking the time.
foamy

 

[NTK]

Welcome to ASR. Glad to have you here.

Now some unfortunate news. Speaker manufacturers' recommended amplifier power is one of the most meaningless "specifications", if not the most. There is no standard on how a manufacturer comes up with these numbers (and they don't explain how the numbers are measured or determined), so across different manufacturers, you are definitely not comparing apples to apples. You also have no idea what those numbers really mean. For example, if it is the maximum rated power, does it mean if the power is exceeded, the speakers will be permanently damaged? If it is, what is the duration? 1 microsecond or 1 second or 1 minute or indefinitely (i.e. the speaker can be played at the rated power indefinitely)? And at what frequency or mix of frequencies? We know that the tweeter can handle a lot less power than the woofer, so the power handling capacity of a speaker is frequency dependent.

The rule-of-thumb I (and many others here) use is the more power the better. If you are going to damage you speakers, you are simply playing them too loud. (That's why the max SPL rating is much more meaningful.) Having an anemic amplifier is not a good solution as you'll probably run into the problem of not having enough power a lot.

 

[Mudjock]

NTK makes a good point about the unknown nature of what that 80W spec means.

Ultimately, your amp and speaker requirements will be based on how loud you would like to listen in what size room. I am a DIY speaker designer/builder and find that if I design something capable of playing 95-100 dB cleanly at 1m distance from the speakers, there will rarely if ever be problems in an in-home setting. If Triangle's sensitivity rating and nominal impedance ratings are reasonably accurate, you are looking at about 5W of amplifier power to hit 95 dB and 20W to hit 100 dB at 1m (calculations are slightly on the conservative side).

In my experience, these are failure modes you have to consider in amplifier/speaker systems.

• Woofer overexcursion
  • In many speaker systems, this will happen before thermal damage to the voice coil. When this is happening, you will hear funny sounds on deep bass passages or very dynamic passages (i.e. percussion).
  • This is most common when small woofers are placed in vented enclosures tuned for maximum bass extension. The BR02 has a +/- 3 dB lower response spec of 51 Hz with a 13 cm woofer. If the woofer response is 3 dB down at 51 Hz, it probably isn't designed to play very loud (Triangle recommends 20 sq meter room or less for best results). If that 51 Hz point is really 6 dB down from the midrange response (which is actually more likely), then I wouldn't be concerned.
• Thermal damage to the voice coil
  • This happens when too much current is sent through the voice coil, and it can't dissipate the heat. This is more common for woofers, but can be an issue if the tweeter is playing down to an unusually low frequency. This is pretty rare when the speaker is playing a normal music signal unless one takes a speaker intended for home use and tries to play dance music in a large venue. Even then, many speakers do fine because music signals usually only draw high current in short bursts.
  • Every time I have seen this happen, it has come down to 1 of 2 issues.
    • Not enough amplifier power to play as loud as called for - signal sent to speakers is clipped and starts to look more like continuous high current than short pulses.
    • Small, but high excursion woofer playing deep bass - these sorts of drivers tend to be very inefficient (more like 75-80 dB at 1W/1m than the 89 dB for your Triangle speakers). In that case, it can take a lot of amplifier power to get the speaker to play loud and this can heat up the voice coil.

I think you will be okay with the Triangle/Onkyo combo unless you have a very large room and like to listen unusually loud. If that is the case, you may need to limit how much low frequencies you send to the speakers and/or incorporate a subwoofer.

 

[foamy]

Thanks a million for the warm welcome and wealth of information! I needed a little time to do some follow-up research based on what you've provided me. There's a little bit of a thought ramble to follow, please share all of your thoughts/feedback/correction/advice, it's all appreciated.

So, my understanding is that there's at least two ways to damage speakers: by providing too much power or providing clipped signal to speakers.

I'm going to focus on the clipped signal issue right now since from my understanding it's the most likely of the two scenarios to occur in this case.

Thinking out loud now...

Clipped signal from the amplifier occurs when the amplifier is outputting its upper power (W) limit but the speaker needs to draw above this in order to realise the desired signal(?).

Can this potential extra power demand by the speaker be calculated from the speaker's sensitivity/efficiency specification?

Then building upon this and the calculations provided by Mudjock above.
Would it be possible to determine a safe operating power (W) output limit to accommodate ample speaker draw demand/fluctuation, without hitting the clipping point? Conservative calculations are good in my opinion also, especially given the stakes.

Then... Could one attach a multimeter to the amplifier output terminals, find the determined safe operating power (W) limit according to volume control position? Assuming it might not necessarily be linear and obtainable as a percentage of the maximum volume position representing 30 W.

Finally, just some information on the listening environment.

The intended room is ca. 10 sq meter, and while I don't have a dB meter to hand I would certainly not consider my usual listening volumes to be loud by any stretch of the imagination. This Hi-Fi adventure is more about hoping to experience new depth from music that I already love as opposed to making myself deaf. If myhealth.alberta.ca is anything to go by, I'll be very satisfied with staying under 85 dB

I can't thank you enough for the detail you've gone to in the above post Mudjock, it's much appreciated!

foamy

 

[raindance]

How big is your room and how loud do you listen?

A multimeter isn't going to help, a scope is needed to show clipping, and even then the data is hard to interpret unless it's a pure sine wave, which music isn't. However, if you can't hear clipping, you shouldn't be worrying about audio gear, just hearing aids.

The challenge with music is clipping on the peaks, but fortunately most music is so compressed that there aren't any.

 

[raindance]

Also, when your amp runs out of steam, the music will start to sound thin, ie bass gets less and treble gets harsh. This is because the amp can't deliver any more current.

 

[foamy]

Hi raindance, thanks for the reply. I've edited my previous post to hopefully make things a little clearer (although it's still awaiting moderator approval).

What I mean above is to use a multimeter to measure amplifier power (W) output at different volume positions, not detect clipping.
The intention is that by knowing and staying below a given power (W) threshold, clipping could be confidently avoided. This is of course only hopeful speculation based on being able to calculate the point (Watts) at which clipping could occur. Again, just thinking out loud

That's interesting what you said about the music starting to sound thin and running out of steam, thanks, I'll bear that in mind.

The intended room is ca. 10 sq meter, and at a guess I would think that somewhere in the region of 95 dB (based on Mudjocks information above) should be more than enough for me. I'd most likely stay below that I think, but it might be no harm to factor it in for distance.

foamy

 

[FloatingPoint]

I have the Onkyo A-9010 (the previous generation) driving a pair of Paul Carmody's Classix II in my basement. The A-9010 is rated at 44w/ch and the Classix are rated 87db. and 8 ohms nominal. I don't think I've ever turned the knob past 12 o'clock. If I have, it was just barely. I think you'll be fine

 

[raistlin65]

The logic I applied to the pairing was based on attempted normalisation of speaker specifications

A better method is to figure out your average listening level in db using an SPL meter. Add some more db for dynamic peaks. Then, since sound decreases by -6db as you double the distance from the speakers, you can calculate what volume in decibels your speakers need to achieve.

Once you know that, there are web calculators where you punch in the sensitivity of your speakers and what db you need that will tell you what wattage you need from an amplifier.

 

[Voo]

I have owned lots of gear last 30 yrs. it all matters. pre amp matters, amp matters, speakers, cables...it all matters. the good news is that it can be done for cheap. avr's usually suck.

 

[raindance]

Triangle speakers are fairly sensitive. I don't think you'll have any issues. Honestly, just hook it up and listen. My first amp was 20 watts per channel and it drove Boston A40's (les sensitive) with ease in a larger room. Where the volume control points to is a meaningless measure; all recordings have different average levels and all amps have different amounts of gain.

 

[Mudjock]

Based on your description of room size and intended listening volume, I think your amp/speaker combo will be more than up to the task.

I think what you suggest for an average listening level is realistic for typical home use. I tend to design for enough headroom to handle peaks without compressing too much and handle the possibility of using the speaker in a larger venue (for instance demonstrating them at an audio show or providing music at a larger gathering). Your combo might even do okay for that, but if you did use them for a large gathering, you might want to borrow a more powerful amp. When considering that, it is important to realize that doubling the power only gains 3 dB's of SPL, which is audible - but not by much...

What we have discussed as possible limitations will come into play if/when you decide to repurpose the equipment.

 

[foamy]

Thanks so much for all of the advice and input. It's great to hear the stories of similarly powerful amps still being up the the task. It's definitely put my mind to ease. I'll leave the multimeter in the toolbox!

The speakers arrived yesterday and I'm blown away by the build quality, weight and substance to them (not that I have any previous reference point at this price though). I am usually aesthetically allergic to plastic laminates, but damn... they're pretty, classy pretty and my wife even thinks so! The arrival of the amplifier isn't looking too good. It seems stock is non-existent due to virus and supply chain issues I guess. Delivery has been pushed back by 2 weeks twice already and I see that some other online sellers are advertising delivery dates 12 weeks from now.

Anyway, fingers-crossed!