Distortion at high volume - Why?

kkennyy

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Hi Guys,

I'm having some issues with setting up a new AV receiver in my home, i hope you can help me understand why and maybe fix it. I'll briefly sum up my history:

I was previosly living in an apartment and my setup was the Onkyo TX-SR608 receiver which powered Magnat Quantum 555 speakers (plus a center and two rears, but i'm interested in music for now). The receiver was rated at 160 W/Ch at 6 Ohms, 1 kHz, 1 Channel Driven, IEC, while the 2 standfloor speakers are 160W RMS with 4-8 ohm impedance. This setup worked very well, music was loud and distortion free even at 0db (reference level).

Recently i moved from that location to a house with a big living room. This meant a bigger tv, 4k, and of course, a new receiver. So my current setup is the Onkyo TX-NR646, rated pretty much the same at 160 W/Ch (6 Ω, 1 kHz, 1% THD, 1 Channel Driven, IEC);175 W/Ch (6 Ω, 1 kHz, 1 Channel Driven, JEITA), and of course the same speakers.

The problem is, when i raise the volume over 60 or so (out of 80max, this doesn't have thx, so no decibel reference volume), the sound becomes distorted. Receiver is set at 6 ohm (onkyo's setting for anyhing over 6ohm). I've tried this on bluetooth and airplay connections, not yet on hdmi or some other higher quality.

My question is, is this normal? Am i overpowering the speakers? Can't tell if 60 right now is higher power then 0db before, given the bigger room. Can the bluetooth/airplay cause the distortion (maybe limited on bandwidth)? Any ideeas on how to improve it? The sound pressure is pretty high, i'm not complaining, it's just that sometimes i would like a bit more.

Thanks very much for any opinions on this subject.
 
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Do you think the Onkyo gets maxed out at 75% volume?

I should add that i get distorting on the low end only. Highs are fine. Speakers are bi-amped.
 
If putting too much strain upon an amplifier then something called "clipping" can occur. When an amplifier is pushed to create a signal with more power than its power supply can produce, it will amplify the signal only up to its maximum capacity, at which point the signal can be amplified no further. As the signal simply "cuts" or "clips" at the maximum capacity of the amplifier, the signal is said to be "clipping". The extra signal which is beyond the capability of the amplifier is simply cut off, resulting in distortion.

I'd actually suggest you set the receiver's impedance switching to its default rather than switching it down to a lower impedance. All you are doing by reducing the impedance is reducing the receiver's rail voltage and therefore making it less powerful and less able to power your speakers.

Also note that the larger your room then the more powerful the amplification will need to be to attain any particulay level of volume. This is because the further away you are from the speakers then the more power is required to attain that level. You don't mention how far you are from the speakers so this makes it difficult to ascertain whether you'd need a more powerful amp for your listening room or not? You should ideally have a setup that can be calibrated so that 0db (reference volume) is portrayed without any distortion within the room you are using it in. Most AV receivers can attain this in your average sized living room.
 
Do you think the Onkyo gets maxed out at 75% volume?

I should add that i get distorting on the low end only. Highs are fine. Speakers are bi-amped.


Are you using the crossovers to divert lower frequencies away from your speakers to the active sub? If not then do so rather than regarding your speakers as being full range. You'll then increase the headroom associated with the speakers be having the more capable sub deal with the harder to reproduce lower frequencies.
 
The receiver's default impedance is actually 6ohm. Switching it down would mean 4ohm, but as you pointed out, it's not to be desired. So the problem is definetely not here. I should definetely get a sound meter to get it calibrated tough.

I don't have any active subs at the moment. Never really felt the need for one, until now. Speakers are set as full range. I thought about buying a sub, maybe now is the time ...
 
'The sound pressure is pretty high, i'm not complaining, it's just that sometimes i would like a bit more' - further down your timeline the least of your worries may be your system not going 'loud' enough.

Use an SPL meter or a Phone with an App to get some idea of how loud you are currently running the system at.

Joe
 
I had a very similar issue to this when I upgraded my receiver to a more powerful unit.

I didn't use a sub at the time and pretty soon I was noticing distorted bass at high volume levels.

As has already been alluded to, it was due to the receiver passing the sub-woofer element of the sound to the floor-standers and they just couldn't handle it. Removing the grilles and watching the excursions of the struggling bass speaker cone removed any doubt.

Applying that bass management should soon confirm if this is indeed the issue. It did it for me, and eventually I bought a sub.
 
Yeah, seems like this is the problem for me also. Just tried to crossover the standfloors at 80hz and there seems to be no distortion at 65 volume. Higher then that i cannot listen, as my ears would pop. Just to have an ideea, i would probably listen to this kind of music at 63, so don't need much more over the distort limit right now, and this over short periods of time, as it would damage my ears.

By the way, i tried an spl meter on android and it tells me i have around 107db. It's definetely loud, don't know how accurate a phone app could be.

In conclusion, it seems i need a sub. Maybe something over 160W (to match my standfloors). I'll be definetely adding it to my shopping list.

Thanks a lot for your input.
 
If measuring the SPL from your seated listening position then 107db is loud enough to permantely damage your hearing. It is advised you don't listen to audio above 90db. An AV receiver calibrates its relative 0db volume to a standardise 75 - 85db so the levels you are listening at are quite a lot higher than you'd ordinarily expect or indeed what would be recommended for safe listening. You are basically damaging your hearing so what the speakers sound like now wont really matter if you continue listening at similar levels.
 
"In conclusion, it seems i need a sub" - a Sub will help out, though I'd suggest you don't want to be listening at such high SPL's on a regular basis.

Possibly time to listen to systems you enjoy which don't need to be cranked so high.

Music and your hearing

Joe
 
So that explains why my previous receiver had no issues at 0db. Beacuse that was calibrated and volume was actually lower then my current volume at 75%.

I know this volume is not good for my hearing, but i like the, let's call it "club" sound, and i listen to it in short periods of time, one in a while. For those few moments, i want to make my system sound as clear as possible, and if that involves a sub to help out, so be it.
 
'but i like the, let's call it "club" sound' - buy a PA system rather than a HI-Fi/AV system, invariably you end up damaging the Hi-Fi/AV kit.

Joe
 
I think a more detailed and punchy bass would make this system more suitable to my ears, even at much lower volumes. Should help with the movies too...
 
I think a more detailed and punchy bass would make this system more suitable to my ears, even at much lower volumes. Should help with the movies too...

What you're lacking is clarity at higher volume. Also measuring with a phone app is not going to be accurate as most phones mics top out at 85dB. Measure it with something properly - 90dB is a live band in a mid sized venue at the desk that's about were health and safety put it.

I recently had a drummer mate who had to swap a cymbal in a smaller venue as it was hitting 105db acoustically.

Sounds like you're trying to get party bass and your floorstanders don't have a chance of reproducing it so you keep turning up. You need a good subwoofer, but you will be deaf after 15 mins at anything above 85dB, your ears will start shutting down so it's biologically impossible to get the loudness you're after.

Demo a sub.. it's likely what you're after and not actual volume.
 
Yeah, i guess the phone app is ridiculos anyway. I would say it's about as loud as a band in a mid sized venue, so more likely in the ~90 db range. Anyway, that's exactly what i'll do, i'll demo a sub. I think it will fix whatever i think is wrong with my setup. Thanks!
 
Yesterday i managed to get a sub and i must say the bass has been greatly improved, really a big difference on some boomy tracks, while also not flooding too much on some cleaner ones, i really like it. Must still tune it a bit to be perfect (playing with the crossovers, currently at 60hz) but mostly i think it better suits the big room, compared to standfloors only.

Still, this led to an experiment on some previously distorting tracks, where the standfloors couldn't cope with the low frequencies at very high volume. What i found out is neither the sub copes with those, so this leads me to thinking the problem is with the tracks themselves. Tried to reproduce the distortion on my turntable for example, nothing, even at crazy volumes. So it's either some specific frequencies that the speakers and the sub can't manage, or, more likely, something wrong with the tracks (mp3 320kbps in those cases).

Anyway, i'm glad i got into this issue, the sub really completes the system well and i don't feel the need for such high volumes as before. Thanks for your input!
 
Plug a CD player into the amp - try the crossover at 80hz or above see how it sounds then.
 

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