Axiom Home Page Forums General Discussion Hearing Things AVR vs Seprerate- Measured

Is it possible amps sound different? Frequency response measurements say maybe.... Or do they?

To be fair, this is a garbage test, including subs not recalibrated between amps. The gain between the amps is slightly different, so the bass in the room slightly differs between tests. Could this be why people perceive a "fuller" sound between amps? Or is there enough variability above the crossover frequency (60hz plus rolloff in this case) to call differences audible. You decide.

The 2ch amp needs a 1.5db boost in the preout settings to match the AVR's internal amp gain I'm guessing, but we're in the ballpark anyway.

2ch amp- 1/12 octave pink noise averaged

AVR - 1/12 octave pink noise averaged

Without more sweeps being run, and blind tests conducted between the two, it's pretty much impossible to make any substantive observations on the two graphs. The general shapes are comparable, and the smoothing applied plus other factors (air movement in the room, slight change in microphone position, etc ... ) are unknowns.

Researching and asking are good things, though.

I thought the graphs would be the same. Slight variations can be seen between 1-4khz. There is more of a tilting into the valley trend with the AVR and a bump right before 2khz. May be nothing.

I dont test using sweeps most of the time, the reason is as you stated, variability. I run pink noise and set the FFT to average the spl per frequency over time. I give it 30 seconds or so, but usually the graph has fully stabilized by the 7-10 second mark.

I use 1/12 octave resolution (twice what we are thought to be able to hear) because 1/3 or even 1/6 resolution can hide narrow high Q problems. Not that we are very good at hearing those either.

As a curiosity, sighted, I preferred the sound at first of the AVR over the power amp..... Once I started to turn it up however, the Amp remained sounding composed while the AVR started to sound brassy. Its hard to describe, but guitars start to sound more twangy with the AVR at higher volumes. Audible distortion perhaps? I would have never noticed it without a comparison like this.

I could be imagining things. I should re-run the measurements at a higher db and see.

I used the track "Timshel" from Mumford and Sons album Sigh No More for testing.

I've been watching/listening to a lot of content lately with my father in law. He is a little older than me and his listening volume preference is a little higher than mine. I would say my average level is somewhere around 60-65db avg while his is 70-75 db avg.

Anyway, I have started to notice brief moments when listening to concerts and the lotr: two towers with him that my AVR was sounding a little strained.

My room is pretty much treated now and I've lived with it long enough to be pretty keen on subtle changes. It is not hard to hear when channel levels are out of whack even a couple db now and it is pretty easy to hear differences in balance when the sub levels are adjusted by a single db in the AVR setup menu.

As a bit of a test I hooked up my 2ch power amp. I'm still waiting to get it properly integrated into my system. Stupid proptrietary gear! I reset the trim levels for the preouts to match the spl of the other channels (75dba) and sat for a listen to some Daft Punk -RAM.

AMPS DO SOUND DIFFERENT. Or do they?

It sounded like a step backwards. I preferred the sound of my AVR I had just bypassed...... What?! I tried to think why as I clicked through tracks and it dawned on me. The towers were now producing bass at levels that were enough of a change to throw out the sub/speaker balance. I turned the sub trim down by 1db. Yes, 1db, and everything fell right back into place.

1db. Wtf. Audio is a strange game.

The amplifier is capable of much more current vs the AVR at any listening level and the entire power balance had shifted towards slightly more bass. Not a ton, but enough I could notice the fingering on guitars in "get lucky" was being masked by what I perceived as bass a little proud of the balance I had.

After the slight adjustment, the balance now sounds right again, and it is indistinguishable from the old setup to my ears.

1db.

I can now listen at any volume and the pitch of the track doesnt shift with loudness, as it did with the AVR. There is no more "brassyness" or hardness at loudish listening levels. I have a few tracks I crank and listen to to relax. I really like Enya's Caribbean Blue loud. So euphoric. I always thought the track had been mixed so the first couple loud tones in the song had a pronounced peakiness or attack to them. They aren't supposed to. My AVR was adding distortion once I poured the volume on. Not at agressive levels either.... Like 80db or so.

Food for thought if nothing else.

For anyone interested, I'm trying to get a technical explanation of why the response of the 2 setups differed over at AVS.

If you wanna see me get beat up soon here you go!

http://www.avsforum.com/forum/91-audio-t...nt-mention.html

And in no small way, because the "mind plays tricks..."

As Craig inferred, this is always fun to do for the sake of fun, but realistically, one requires a very controlled setup to determine the most valid results.
It has long been published in science literature that human audio memory is very short. Without an instantaneous switching method the observations anyone makes (and believes are real) are subject to bias. It doesn't matter if a person had a 20 year musician in the room, or their wife who never heard the setup the first time, etc. etc.

All that being said, and taking Craig's comments re: room atmosphere alone into account, the two graphs produced are EXTREMELY similar (overlay the two and you will see how little difference exists; anything at delta 1dB for a minor frequency range would not likely be audible). If repeated and averages over multiple trials, i would doubt there would be any statistically significant differences in those curves and for the most part, that was already demonstrated for most of that spectrum reproduction.

The suggestion that the AVR is being strained in its power output is certainly plausible depending on the playback SPL and speakers being driven. I have found our AVR to have a change in sound as SPL increases much earlier than i ever expected, though the point at which i "perceive" that to be happening is still pretty loud (>85 dB at 11 feet).

BTW, that's a nice looking amp!

I haven't ventured over there in years b/c of the idiots that exist in droves, but surprisingly you've got a few decent responses so far that hearing damage at high (and clipped) SPL, as well as noting importance of DBT (double blind tests). I didn't think anyone over there supported such a logical notion.

I think i'll stop looking at the thread while it still remains civil.

I am in the midst of changing out my equipment.

As this thread is about separate components, I figure that I would chime in about my experience. I personally found that my Pioneer AV receiver doesn't produce as pleasing a sound as my older Yamaha amp. I think that has something to do with the Yamaha has an older A/B design amp with a sizably large transformer. Where the Pioneer has moved to a more efficient Class D amp bit it just doesn't have what it takes to power a 4ohm speaker.

I have an Anthem that is a large Toroidal Transformer with it's Class A/B amp and produces a warm sound that is very enjoyable. Rated at 200w @ 8ohm, I am told it is stable down to 2ohm.

I have pulled the Anthem from my rack and started using the AudioSource One/A amp. This is an 80w @ 8ohm and is supposed to be stable down to 2ohms as well. I have a pair and use them to drive my LFR1100 speakers, but find the sound is not as pleasing as what I got from my Anthem amp. it just doesn't feel as warm and at volume feels a bit more lacking. I don't know if it's the design of the amp or the 120w less power in the unit. There would also be less current capacity inside the amp.

All un-scientific view based on sighted tests. It's not that I have some opinion one way or another that something should sound better so it does. I don't know.