Is my AV reciever under powered?

barmyllama

barmyllama

barmyllama

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Did my amp overheat because of a lack of ventilation or am I asking too much of it to drive my system?

Here's what happened and my set up.


I was watching a blu ray movie today, at a decent volume, about two thirds of the way through my amp switched off and the standby light was flashing. The top of the amp was very hot to the touch so I assume it's overheated and tripped out.

The amp isn't enclosed at all except for a glass shelf about 40mm above it. TV unit is an Off The Wall Origin S3 and the amp sits on bottom of the unit.

https://off-the-wall.tv/products/origin/

I have a Denon X2300 AV receiver. Probably a couple of years old and it's never tripped out before.

It's running a 5.1.2 speaker set up comprising of Q Acoustics 2050i fronts, 3090 centre and two pairs of 7000 as rears and heights. With a BK Gemini II subwoofer.

Crossovers are set to 60hz front, 90Hz centre, 110Hz rears and 200Hz height

Speakers are rated as follows.

Floorstanding fronts: Frequency Response (+/- 3 dB), Recommended Power: 25-150w, 6ohm Nominal Impedance, 4ohm Minimum Impedance, 92dB Sensitivity

Centre speaker: Frequency Response (+/- 3 dB): 75Hz - 22kHz, Nominal Impedance: 6ohm, Sensitivity: 89dB, Recommended Power: 25 - 100w

Rear and height: Frequency Response (+/- 3 dB): 95Hz-20kHz , Nominal Impedance: 6ohm, Sensitivity: 85dB, Recommended Power: 25 - 100w
 
The heat you felt certainly suggests that the amp was working very hard. If you're using bare wire, then it's worth checking for bits of stray wire bridging the speaker terminals at the amp end and also at the speakers. If all that's okay, then it's the amp struggling with the loads (speakers and speaker cables) and the volume.

Your Denon makes about 65W per channel as a real-world power delivery. The 6 Ohm speaker rating means that the amp is burning through the power a lot quicker than it would do with an 8 Ohm speaker. The relatively-low sensitivity of the rears and heights isn't helping either. When you have a look at the speaker set-up menu screen, how are the dB levels for those speakers compared to the front left?

Speaker wire can also have a suprisingly-large impact on the power from the amp too, especially where speaker impedance is low.
 
Thanks for the reply. I'm using banana plugs so it's not a short. Speaker wire is 2 x 1.5mm Multi-Strand 260 (2x 130 Strand) Outer Dimensions: 6.5mm x 3.1mm. Don't know if that's good or bad. It wasn't expensive.

I'm not sure if this is the setting you're referring to but

I have the rears at -3db each and the heights at +7db each. The other speakers are at 0db.

Any suggestions on an amp with enough power to drive my speakers?
 
Before you look at changing your amp, have a think about your speaker cable. You could be throwing 40% of your power away simply because of wire choice.

I can't be 100% certain it's the same product you have, but Googling seems to throw up the same product via Ebay and the Rain Forest place that comes from a seller called Electrosmart. Prices vary, but the lowest price I've seen so far is 100m for £29.99. That netts down to 30p per metre, and that price includes delivery. The specs are incredibly vague.

The bottom line is that it's not possible to sell 1.5mm 100% copper cable for 30p per metre. Copper costs more than that. Something doesn't add up. The vague specs are a clue.

The answer is that this is almost certainly an aluminium speaker cable that has a copper "flash" finish bonded to the surface. To a casual glance it looks like far more expensive solid copper cable, but it isn't. The industry term for this type if cable is CCA. It stands for Copper Coated Aluminium.

Aluminium is much cheaper than copper. It's a lot lighter in weight, too. However, it's nowhere near as good a conductor. Using copper as the benchmark, Aluminium wastes 40% of the power transmitted down the cable due to higher resistance. Slick salespeople and marketeers try to spin the benefits of the copper coating by talking about skin effect. It's bull crap as far as power loss is concerned. I've even heard folk trying to justify CCA cables by saying that aluminium is used in high tension power lines. It is, and when we start driving our speakers with 100,000~400,000 volts then maybe aluminium speaker cables will have their day. Until then, we'll continue driving our speakers with 0~30 volts (approx), and anything up to 10 Amps of current, for which we need bloody efficient conductors and that means 100% copper of an appropriate thickness for the cable length.

The other issue is the individual conductor sizes. There is a point at which the individual strands become so thin that they're no longer good conductors for low voltage, high current signals. For speaker cable, we are balancing efficiency, flexibility, cost and (depending on your view of thiese things) the sound too. The optimum for a 1.5mm cross section speaker cable appears to be about 80 strands. 40 strands for a 0.75mm. A cable with 100+ filaments per 1.5mm connductor isn't working to the advantage of the system.


A question of time and money

Suggesting to someone to change their speaker cable before changing the amp sounds crazy, right? Not to mention, a whole heap of work. But there's a very good reason to do this; and it's the cost of Watts.


10 mtrs of cheap 1.5mm CCA cable costs under 30p per metre. 10 mtrs of decent 100% copper stuff costs 90p per metre (probably plus delivery). Lets say a system requires 70m of cable. Our cable cost is £21 vs £63. The difference in cost is £42, and if we allow £8 for delivery of the decent stuff we get a round figure of £50.


Lies, damned lies and manufacturer specifications

We know that aluminium is a rubbish conductor compared to copper, and it will throw away 40% of the power sent down it. Your amp is 65W per channel. Wasting 40% of that means losing 26W per channel. To make up for the power wasted by the £50 cost saving in speaker cable, we need an amp that can deliver a real world power of 90W/ch in to 7 speakers.

That doesn't sound so difficult until you realise that spec sheet power figures are not the same as real worrld power figures. Your X2300 claims to be 7 x 150W, and yet you're still running out of juice; so what gives?

The answer is in how the manufacturers fiddle the figures.

For a more reliable real world power figure, take the mains power consumption, then knock off 10% for heat losses and running the pre-amp features. Then divide what's left by the number of powered speaker channels. Your Denon is 500W. Working the sum through gives 500 - 50 = 450, then 450/7 = 64.28 W per channel.

Starting from a target of 90W/ch real world and then working back gives us a mains consumption figure of 700W for a 7 channel receiver, but you're going to struggle to find that. The closest Denon gets is their X3500h which is a 600W mains consumption receiver. That'll give you 77W/ch real world power. The rub is the price. It's £900.

You have a toss-up then. Spend a small amount of money on better cable to get the power through from your existing amp. Or, spend a huge lump of money for a halfway house solution. £50 versus £900. That's the true cost of the Watts.









Denon X2300 spec: https://www.denon.co.uk/uk/product/homecinema/avreceiver/avrx2300w
 
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I'd imagine it would be heat, the denon amps run mega hot! (I have a 2400 model, but never had it cut out)

Edit: great informative posts from @lucid !

I know I paid a bit more for hifi speaker cable! Shame if it's already hidden in walls etc tho!
 
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Thanks Lucid for taking the time to write a detailed and informative post.

Yes you're correct the cable came from Amazon.

I certainly like the idea of spending £50 rather than £900.

Can I be cheeky and ask for cable recommendation?
 
As long as it's 100% copper, and at least 1.5mm cross-sectional area (CSA) then it'll do.

- Monoprice Nimbus Series 14 Gauge AWG 2 Conductor is available in white or black, and 2.08mm CSA. The price is £70 for 250ft (76m)

- Bandridge OFC Oxygen Free Copper Loud Audio/Speaker Cable 2 x 1.5mm² is £80 for 100m reel

- Fisual Dualcon is on clearance at 99p per metre at the moment.



AWG - American Wire Gauge - the smaller the number the thicker the wire. 14 Gauge is 2.08mm CSA. 16 Gauge is 1.3mm CSA
 
And with no pre outs can't connect to your Denon won't power speakers just sit there as an expensive paper weight.

Still you'll never need more power if you get one ( or lower power ATI)

I would say 4 ohm speaker and low sensitivity a problem with your amp
 
Cable power handling is directly related to the cross section of the cable. Given alu and CCA are less conductive than pure copper, the cross section has to be bigger to compensate. look at 16AWG copper vs 14 AWG pure alu

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The difference in resistance per 1,000 feet is withing 0.13 ohms. At 1,000 feet.

Now, assume your putting 50v at 4 amps in to 10ft of cable = 200watts. the voltage drop on 16AWG copper would be around 0.65%. for 14AWG alu.....0.66%. It's within 0.01%. And that's pure alu, not CCA which will be slightly closer (for what it's worth) to copper.

In other words, i don't expect the cable to make a difference unless there's something wrong with your current stuff.
 
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I bought 2 X 2.5mm 99.99% OFC cable.

Amp hasn't tripped out so far.

Not sure if it's a placebo effect but sound seems to be a touch louder at the same volume than before.
 
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