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Is my amplifier likely to be transparent? Pioneer VSX-AX4avi.

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#1
Hi, I have the above multichannel home theatre amplifier which I use for 2 channel music playback. It has the following rated playback specs:

Continuous Power Output – Stereo
Front. . . 180 W + 180 W, (DIN 1 kHz, THD 1 %, 6 Ω)
Front. . . 150 W + 150 W, (DIN 1 kHz, THD 1 %, 8 Ω)

Rated Power Output – Stereo (20 Hz–20 kHz, 0.09 %, 8 Ω)
140 W+140 W

I currently use an iFi micro iDSD (silver version) as the DAC with an Allo USbridge for network bridging to a Roon Server. My speakers are quite good, Image Revelation, specs can be seen here: http://imageloudspeakers.nz/series-image/speaker-image-revelation2/ . Average sensitivity is 90db/watt. I use the amp in 'pure direct' mode which avoids all DSP. I also have a 10 inch powered subwoofer (Velodyne CHT-R) which is wired in parallel with the front speakers and connected to the high level speaker inputs. The crossover on that is set to 35 hz. I have measured the room using Room EQ Wizard and a UMIK-1. I used that to set the subwoofer volume relative to the fronts and positioned my speakers at the best compromise for a balanced frequency response without comb filtering. I have applied some minimal eq as a result of this which improved the sound somewhat. I don't think that the room is particularly challenging. It is carpeted and draped and furniture is well clear of the speakers.

What I am struggling with is getting tracks with a high energy content to sound good, particularly rock music. Things tend to sound great until the music gets into sections with distorted guitars and clashing cymbals. Any sections of music of this nature sound noticeably flat and harsh, with a lack of space around the instruments and a collapsing of the soundstage. My previous speakers (B&W DM603S3) were exhibiting this effect also but to a greater extent. Some tracks are worse than others (which is to be expected with varying standards of mastering).

If anyone can let me know their thoughts on this it would be much appreciated. Where should I focus my attention to improve the sound further? I'd like to get my system to the stage where I can just sit back and relax, and listen to the music rather than worrying about the sound!
 

nightfishing

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#2
My guess would be that some more clean power would help in driving those speakers. I had a similarly speced onkyo (686) that had issues driving my elac and/or KEF bookshelves. Upgraded the power and the speakers started to sing. Chased a lot of other parts before figuring it out. I may be wrong, I don't have any experience with pioneers of that era.
 

andreasmaaan

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#3
What levels are do you listen at normally, and what levels are you listening at when audible problems begin to become apparent?
 
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#4
Thanks for your replies. I haven't measured my listening volume sorry. But usually probably around 60-80db depending on my mood. I'm rethinking this and think there should be plenty of headroom with the amp. I'm noticing a bit of fatiguing brightness even with the good sounding tracks. So I'm thinking that early room reflections might be contributing. The seating position is fairly close to the rear wall. The room is 5.2m long by 4.2m wide, so not a large room. (17ft x 14ft). This is an area I know little about.
 

restorer-john

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#5
What I am struggling with is getting tracks with a high energy content to sound good, particularly rock music. Things tend to sound great until the music gets into sections with distorted guitars and clashing cymbals. Any sections of music of this nature sound noticeably flat and harsh, with a lack of space around the instruments and a collapsing of the soundstage. My previous speakers (B&W DM603S3) were exhibiting this effect also but to a greater extent. Some tracks are worse than others (which is to be expected with varying standards of mastering).
Welcome to ASR. :)

Perhaps consider taking some of this music to a local HiFi store and listen on other equipment. It may be inherent in the recordings, the level you play at, or it may highlight deficiencies in your gear and/or room treatment/speaker positioning.
 

Blumlein 88

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#6
restorer-john offers a good suggestion.

Home Theater gear is notoriously iffy on power amps. If they had ample current the spec from 150 wpc at 8 ohms would be 200 wpc at 6 ohms. So it is already current limiting with a very modest increase in current into a 6 ohm resistor.

You may or may not know this, but speakers don't represent a resistive load like amplifiers are tested with. They have reactance. Which can cause unexpectedly high amounts of momentary current to be asked for when playing loud music. So an AVR with 150 wpc might be wimpy on the current capability and choke when asked to play back music over an actual speaker. While another 150 wpc amp with hefty power supplies and good current capabilities would play right thru it with ease.

I see your speakers are rated at a nominal 4 ohms. If your amp has no ratings at 4 ohms it probably is struggling already to handle your speakers. While they are efficient they may be asking for more current than your amp is able to easily provide.
 
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#7
Thank you. Interesting. In response to your reply I found a thread on another forum referring to a measurement of the amp, saying it had a poor 4 ohm performance. Unfortunately the original review they were referring to cannot be found any more.

I still have a lot to learn.
 

Blumlein 88

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#8
Thank you. Interesting. In response to your reply I found a thread on another forum referring to a measurement of the amp, saying it had a poor 4 ohm performance. Unfortunately the original review they were referring to cannot be found any more.

I still have a lot to learn.
I think you are in a good place to learn. People here are very helpful.

So if your amp is poor at 4 ohms that is probably the answer. At least get one rated for 4 ohms. And don't forget restorer-john's suggestion to try your music on another system. It might be in the recording.
 
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#9
What would be a good guideline for a 4 ohm rated amp? I've read that twice the rating for the speakers is a good guide, which would mean I would need a 400w @ 4 ohm amp. But that seems like total overkill for the size of the room, so maybe I can go for less. Also, I've got an RME Adi-2 Dac on it's way, I understand I could avoid going through a preamp with that. But still think maybe I'd want to avoid too much power in the amp, otherwise I'd have use a lot of attenuation? My other option is to route through the existing receiver and feed a power amp through the pre-outs. This would be good if I could not have too big a volume differential between the L-R and rear speakers, so I can make some level adjustments for the rear and still continue to use the system for movies as well as music. I guess my other option would be to have a switch box of some kind.
 
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