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Can an amp be fatiguing?

qui

qui

New Member
Hi, I'm fairly new to hifi, so apologies if this is rambly/unclear.

My setup:
- Polk SDA CRS+
- NAD 7155 or Yamaha RX-385
- Sony PS-2000 w/ Sony VC-8E
- MacBook Pro M4 or JVC XL-V282 for digital

My first amp was the Yamaha RX-385. I would describe the sound as clean, clear, but lacking oomph. Altogether very listenable for long sessions. The problem I'm facing now is that I recently picked up an NAD 7155 which sounds a lot better on the whole, bottom end is much more fleshed out, but it also has a weird quality that I'd describe as "oppressive". It's like when you're in the movie theatre and there's an explosion, or something with really heavy low frequencies, and it makes your ears feel "full". It's honestly hard to listen to for long periods and it's not really enjoyable in the same way that the Yamaha is. I should mention that its more noticeable when using the Mac as a source than the CD player or the turntable, but it is noticeable for all of them.

Is this a real phenomenon? Am I imagining it? Is there something wrong with my amp and how would I test it? I've already cleaned the potentiometers on both amps, as they were pretty scratchy when I got them. The NAD was actually triggering its protect mode when changing volume at higher volumes.
 
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Sounds more like bass management issues to me but there are differences in the sound of amps due to how they control woofers. I think polks are great speakers but better amps can reach deeper with them and you might just now be noticing a bass trap is a useful thing.
 
Or...... sell the NAD and use the proceeds to add a sub. You love the Yamaha sound but it just lacks a bit of oomph so give it a little bit with a sub. No need to reinvent anything - just add what you want. It will be a lot easier and more likely to get you to where you want to be. It's what I would do - I like the paths of most likely to succeed.
 
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The NAD is a great unit with a lot of headroom. That said, NAD stuff often needs service to be at its best. Not only the pots, but the internal switches. It's old enough for caps to be going bad, but without a good look on the bench it's hard to know. IMO, it's a keeper regardless. Time to look at speaker placement, bass traps and whether your stands put them where they need to be.
 
Set all tone controls to neutral. Turn off "Loudness". Set robust playback level for reference music, Then.

Move speakers to different locations.

I've had good results just moving the speakers closer, Away from the wall's.

My favorite classical conductor story is ***** always rejected masters saying.. Too much bass...

One day someone visited the conductor and moved the speakers off the floor on-to shelves...

From that point on the conductors recordings had great bass.... dang...

TRUE STORY...

Buck
 
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I went through my NAD phase. 1988 to about 2018. So a good thirty years. At the end things just didn't work quite as well as they did before. Also I think I tired of the look. Found a Technics SU-V6 on Ebay for a great price and went that way. Unfortunately I drove that amp a bit hard one day and kind of killed it. Oops... Gifted the NAD away. Now I still have Technics. I have always liked the brand, even though now I realize that there were different levels of quality between different models. They went the way of BPC as well. But I have a couple of good units. An MCS 3842 (Technics). Discrete ouptuts and sounds good. A Technics SU-V707 that I just got from England. Have not even fired it up yet with speakers. Really need to do that. But I had one before and it sounded very good.

With all vintage units there may come a time when it will need to be serviced. Just part of the hobby. And frankly I have two other amps. One Scott and one MCS (NEC) that are both really good units. So much stuff out there to simply stay using one thing if you have the opportunity to try others. Finding good amps is a little bit of luck and a lot of patience. But you will know it when you hear it. And remember that there is no one size fits all. Each to his own...

It's an addiction. But a good one...
 
So many variables indeed, I would posit that it could include the speaker cross overs ( internal restoration need?).
Try getting an NAD cd player
 
May be room issues. Nulls and peaks that make for excessive bass in spots. Moving speakers around is a free thing you could try to see if it helps any.
 
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Would be interesting to run a sinewave at, say 2kHz through the amp and observing the outputs on an oscilloscope while connected to the speakers.
I suspect asymmetrical distortion.
 
Although I've not really encountered it, you hear people talk about "synergy" when certain components are paired. Perhaps your particular combination works best with one amp over the other?

Any real electrical testing would require some equipment and skills. Do you have any test equipment like an O'scope and signal generator?

"Listening" tests could be done but would require a calibrated microphone like a UMIK-1 and software like Room EQ Wizard i.e. REW. That would allow you to do frequency sweeps of each amp and see if there were any difference in the response.
 
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There is a 10 watt per channel difference with the NAD being more powerful.

Something to take into consideration?


Q
 
Buck Rogers said:
Set all tone controls to neutral. Turn off "Loudness". Set robust playback level for reference music, Then.

Move speakers to different locations.

I've had good results just moving the speakers closer, Away from the wall's.

My favorite classical conductor story is ***** always rejected masters saying.. Too much bass...

Later, Some one visited the conductor and moved the speakers off the floor on-to shelves...

From that point on the conductors recording had great bass.... dang...

TRUTH...

Buck
Click to expand...

gadget73 said:
May be room issues. Nulls and peaks that make for excessive bass in spots. Moving speakers around is a free thing you could try to see if it helps any.
Click to expand...

This seems to be the problem, thanks guys. I was following the Polk setup guide that recommends a very short distance between the wall and the passive radiator on the rear of the speakers; I had them at about 8 inches. I suppose my room is too small or something, because moving the speakers about 20in from the wall seems to have helped a whole lot. Spitballing, but I've been reading about the current capabilities of the NAD, and I'm guessing that while the Yamahas output is only 10w lower/channel, it just couldn't push the same current that the NAD can. Even at low volumes the NAD provides noticeably more "body" to the sound. However, this could just be the difference between the "Yamaha sound" and NAD I suppose, I just don't have enough experience at this point I think. And yes, loudness is off lol.

Thanks all.
 
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qui said:
Is this a real phenomenon? Am I imagining it? Is there something wrong with my amp and how would I test it? I've already cleaned the potentiometers on both amps, as they were pretty scratchy when I got them. The NAD was actually triggering its protect mode when changing volume at higher volumes.
Click to expand...
It's real, just hard to sometimes pin down to one thing (or one unit in a system). I find that systems that put an "edge" onto bright sounds often become fatiguing — whatever the reason for that unnatural edge.
 
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Being too close to the wall may have reinforced the bass a little too much. Possible the Polk guide was written with that in mind.
 
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