Amp question

[VMPS-TIII]

My March Audio P452 Purifi based amp has 26.5dB gain spec. I was a little concerned about that with the Denon 4700 RCA inputs. However, in reality it translates into a 2dB gain loss. Where the Sierra Towers were set at -2dB in levels with Audyssey using the Monolith 7X, they are now set as 0dB in Audyssey with the P452.

 

[PENG]

My March Audio P452 Purifi based amp has 26.5dB gain spec. I was a little concerned about that with the Denon 4700 RCA inputs. However, in reality it translates into a 2dB gain loss. Where the Sierra Towers were set at -2dB in levels with Audyssey using the Monolith 7X, they are now set as 0dB in Audyssey with the P452.

That sounds about right and predictable, but the real issue is about the pre out voltage needed for the power amp it feeds to reach the specified rated output. In this case, 250 W into 8 Ohms according to the Rotel's power output specs. Calculations shows it will be almost 2 V, that is a fact, and reality.. And we already know how poorly the NAD T758 V3's pre out perform at 2 V, unlike your X4700H.

The NAD sits right at the bottom of the ranking chart lol!!

 

[VMPS-TIII]

That sounds about right and predictable, but the real issue is about the pre out voltage needed for the power amp it feeds to reach the specified rated output. In this case, 250 W into 8 Ohms according to the Rotel's power output specs. Calculations shows it will be almost 2 V, that is a fact, and reality.. And we already know how poorly the NAD T758 V3's pre out perform at 2 V, unlike your X4700H.

The NAD sits right at the bottom of the ranking chart lol!!

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In an ideal world these speakers might be a better fit for a Yamaha AVENTAGE RX-A3080 or a Denon 4700 with Monolith or Outlaw amp. Or maybe even the Hegel H90 integrated amp. I'm still surprised how the Hegel H90 60W amp sounds better to my ears than many 200W amp configurations.

 

[PENG]

In an ideal world these speakers might be a better fit for a Yamaha AVENTAGE RX-A3080 or a Denon 4700 with Monolith or Outlaw amp. Or maybe even the Hegel H90 integrated amp. I'm still surprised how the Hegel H90 60W amp sounds better to my ears than many 200W amp configurations.

I agree with you on a lot of thing but you know not about that 60 W of the Hegel being comparable to real power amps such as the Monolith 200W or Outlaw monoblock. 60 W is 60 W if the specs is honest, it may be 120 W into 4 ohm if it can truly "double down" but not more than that, no magic there, sorry. I understand you are very happy with the "sound quality" of that amp, and I am happy for you.

 

[ski2xblack]

I suspect that the good Doc is correct. He usually is. Swerd, too. Current limiting would certainly explain the OP's predicament.

But it's a shame that an AVR with an msrp of $1400 or so can be such a dud with real world, reactive loads, or exhibit such mediocre performance on the pre/processing side too.

 

[VMPS-TIII]

The first watt is the most important watt for me. Who cares what an amplifier sounds like at 200 watts if it sounds less desirable at one watt? While a 200W rating is nice, it doesn't tell the user whether that particular receiver/integrated amp will sound better to their ears than a unit with a substantially different power rating.

As usual, this all depends on the size of the listening area, sensitivity of the speakers and the loudness level. My listening levels are usually at 80dB or less. Users looking for loudness more than the quality of sound at 1 watt may have a different view.

 

[PENG]

The first watt is the most important watt for me. Who cares what an amplifier sounds like at 200 watts if it sounds less desirable at one watt? While a 200W rating is nice, it doesn't tell the user whether that particular receiver/integrated amp will sound better to their ears than a unit with a substantially different power rating.

As usual, this all depends on the size of the listening area, sensitivity of the speakers and the loudness level. My listening levels are usually at 80dB or less. Users looking for loudness more than the quality of sound at 1 watt may have a different view.

Sure, If you look at ASR's THD+N vs Output curve you will know how the amp performs in the first watt, in distortions. Such info is available for the Hegel H160 by Stereophile, and the few Denon/Marantz measured by ASR.

 

[tmurnin]

Now this whole thread has me wondering if the real correct thing to do is to sell the NAD and just get a better pre-pro/amp or AVR. That will obv cost more than $500, but if the ultimate issue is with the NAD power and an amp is unlikely to help, perhaps I should replace it?

Ideally I'd find some separates that would support basic video (I need about 3 HDMI inputs) but with a focus on audio. I don't want to deal with ARC or running video direct from source (AppleTV and cable box) and audio into the processor, so an integrated amp is probably out as well. This is really where I want the focus to be on great audio - we occasionally turn on a sports game or something if we have friends over, but HT is not what I'm looking for.

 

[Alex2507]

an amp is unlikely to help

That's not a forgone conclusion. Is it? And you can return the amp if you don't like it? Or you could sell it to me for $250.

 

[ryanosaur]

To the Monoblock question before, @tmurnin , yes you can stack them. Outlaw recommends no more than 3 high. Mine, even in spirited sessions, never get more than slightly warm.
I like Monoblocks because each speaker has its own power supply. I am never concerned about my program material and whether I may be taxing the amp stage of my AVR. For that, my AVR is more than adequate to handle the demands of Rears and eventually Atmos.
As to whether you should upgrade the AVR now... or later? That's a toss up. It works, but power is questionable. Amp may help in your situation. I cannot speak to the manner with which that NAD of yours handles the processing duties. If it is capable of outputting a clean signal to the External Amp(s), then you have no reason to ditch it and can put in on the 2-year plan.
On the other hand, just swapping out now can save you some headache, but will be a more immediate and larger investment than you seem to want to commit to right now.

Personally, I would look at the Amps now, and see if you can make the AVR work for the rest of its useful lifespan, or as I suggested, put it on a replacement plan in next year or two. The Amps will be nice for a long time to come if you get solid tech. (No experience with that Rotel, so I can't help you there.)

 

[AcuDefTechGuy]

Now this whole thread has me wondering if the real correct thing to do is to sell the NAD and just get a better pre-pro/amp or AVR.

Audio 101. Lesson #1. Get a Digital SPL meter for $50 and measure how LOUD you listen from your 10ft listening distance.

If you already have some kind of SPL meter, use that.

Report back to us for Lesson #2 before everyone else continues to jump to conclusions ALL OVER CREATION.

Jumping to conclusions is exactly what happens to most people. They end up selling and buying and end up worse than where they started (at least financially).

 

[AcuDefTechGuy]

That NAD unit is going to be way under powered and I highly doubt it will give its rated power into those speakers.

I think he needs an amp that can deliver at least 150 watts into a four ohm load.

So when S&V Magazine measured that NAD AVR and measured an output of 164 Watts Continuous x 2Ch into 4 ohms, this is FAKE power or something? Because it came from an AVR? It’s only REAL power if it came from an “Amp”?

 

[tmurnin]

Audio 101. Lesson #1. Get a Digital SPL meter for $50 and measure how LOUD you listen from your 10ft listening distance.

If you already have some kind of SPL meter, use that.

Report back to us for Lesson #2 before everyone else continues to jump to conclusions ALL OVER CREATION.

Jumping to conclusions is exactly what happens to most people. They end up selling and buying and end up worse than where they started (at least financially).

I have an old radio shack meter that I can use tomorrow but will say my everyday listening isn’t what most people would consider very loud. There may be a party 2x/year where we’re cranking the volume but that def isn’t typical

 

[ski2xblack]

You cou

So when S&V Magazine measured that NAD AVR and measured an output of 164 Watts Continuous x 2Ch into 4 ohms, this is FAKE power or something? Because it came from an AVR? It’s only REAL power if it came from an “Amp”?

Those results were produced using a purely resistve load. Aczel style power cube measurements would be more revealing.

Look at the ST impedance/phase plot, particularly the spot above 2khz with the steep negative phase angle that TLS mentioned. The effective load at that point drops below 4 ohms. Thats the sort of reactive load that will expose current limits of the amp, or trigger some sort of busybody thermal protection circuitry that cuts power (protecting the avr from heat, but simultaneously preventing it from properly driving the speakers, and even putting them at risk by causing clipping at lower power levels).

Hey @tmurnin check and see if your NAD has a speaker impedance switch on the back. If so, putting it in the high impedance setting will bypass some of the current limiting safety circuits and allow the greatest power output. It will generate more heat that way, but it may unleash the amps enough to drive the salks properly.

 

[AcuDefTechGuy]

SongTowers are clearly 4 ohm speakers. Look at the red trace in the 200-300 Hz range. Their mild phase angle changes, less than 90° in that range, are what makes them relatively easy to drive – for a 4 ohm speaker.

So they are relatively easy to drive 4-ohm speakers with 88dB/2.83V/m sensitivity.

The NAD has been measured by S&V Magazine to output 164W x 2Ch into 4 ohms Continuous.

@PENG based on these facts and the fact that the OP sits 10FT away from the speakers and he does not listen very loudly (he will measure SPL, but I think we get the picture), is there reason to believe that the NAD doesn’t have enough power?

Should we DOUBT all AVR power measurements because the real life speaker load is a lot more difficult than in the lab? For example, the old Denon 3000- series that was able to survive the 1-ohm load in the lab would be killed in real life?

 

[Swerd]

So they are relatively easy to drive 4-ohm speakers with 88dB/2.83V/m sensitivity.

Yes, that's what I previously said. Easy to drive for a 4-ohm speaker is not the same as easy to drive for an 8-ohm speaker. In my hands, SongTowers could be adequately driven by a mid-price Denon AVR capable of 70 wpc. It was my experience (in my home, with my listening preferences, yada yada) that these speakers benefited when they were driven by a 200 wpc external amp. This question about 'what is enough power' has answers in many shades of grey. Don't look for black or white answers.

The NAD has been measured by S&V Magazine to output 164W x 2Ch into 4 ohms Continuous.

… based on these facts and the fact that the OP sits 10FT away from the speakers and he does not listen very loudly (he will measure SPL, but I think we get the picture), is there reason to believe that the NAD doesn’t have enough power?

ski2xblack already responded to that.

Normally, I would be inclined to accept the S&V results. I, along with others have learned, over the years, that NAD receivers don't always seem to deliver the power that they claim. Is this universally true for all NAD products, with all speakers, under all circumstances? Of course not. I didn't say that. This question does not have simple yes or no answers.

Should we DOUBT all AVR power measurements because the real life speaker load is a lot more difficult than in the lab? For example, the old Denon 3000- series that was able to survive the 1-ohm load in the lab would be killed in real life?

Now you're being absurd. I think you know better.

 

[lovinthehd]

If not listening at significantly loud levels it would be hard to believe there would be a significant change by changing amp....but staying tuned in....sometimes ya just gotta buy that amp to scratch the itch (and then find out how little difference it can make)

 

[Mikado463]

Yes, that's what I previously said. Easy to drive for a 4-ohm speaker is not the same as easy to drive for an 8-ohm speaker. In my hands, SongTowers could be adequately driven by a mid-price Denon AVR capable of 70 wpc. It was my experience (in my home, with my listening preferences, yada yada) that these speakers benefited when they were driven by a 200 wpc external amp. This question about 'what is enough power' has answers in many shades of grey. Don't look for black or white answers.
ski2xblack already responded to that.

Normally, I would be inclined to accept the S&V results. I, along with others have learned, over the years, that NAD receivers don't always seem to deliver the power that they claim. Is this universally true for all NAD products, with all speakers, under all circumstances? Of course not. I didn't say that. This question does not have simple yes or no answers.
Now you're being absurd. I think you know better.

the sad thing is 'back in the day' it was just the opposite, NAD was known for conservative specs whereby they offered superb headroom.

 

[AcuDefTechGuy]

In my hands, SongTowers could be adequately driven by a mid-price Denon AVR capable of 70 wpc.

It was my experience that these speakers benefited when they were driven by a 200 wpc external amp.

NAD receivers don't always seem to deliver the power that they claim.

Now you're being absurd.

I'm being Absurd?

You're the one claiming pairing these Salk speakers with a 200WPc amp will "benefit" the sound when a 70WPC AVR sounds just fine. Didn't they even use a weak Tube amp to power these Salk speakers at an audio show like TLS Guy say? If more power will benefit, why did Salk use a weak tube amp at the show?

And we're not taking about what NAD CLAIMS. We're talking about what was actually MEASURED by S&V Magazine.

It's absurd to say that you believe the measurements by S&V are okay, except for NAD.

 

[Swerd]

Didn't they even use a weak Tube amp to power these Salk speakers at an audio show like TLS Guy say? If more power will benefit, why did Salk use a weak tube amp at the show?

You've got important details wrong.

TLS Guy heard a 35 wpc tube amp driving SongTowers when he visited the amp maker, Frank Van Alstine, in Minneapolis. I've also heard that same combination, and I agree that the amp's power was inadequate. It's lack of power could be most easily heard in the bass frequencies.

At that time, Jim Salk would often team up with Van Alstine at audio shows, but both preferred to use large and expensive solid state amps, such as this, or hybrid tube-solid state amps, such as this, all made by Van Alstine. Jim Salk never claimed that tube amp was a good choice to drive any of his speakers. Neither did Dennis Murphy.