Crown Amps, the hype is real!

[SoCal Sam]

Square wave performance is a red herring if you're not troubleshooting a broken amp. The rise time and ringing are the result of output inductors and Zobel networks, not to mention the frequency response of the signal generator and cable impedances. You don't need (or even want) power bandwidth too far into the ultrasonic, no good can come of that. If you're -3dB is at 100kHz, past about 10kHz your square waves become decidedly less square. But who cares? By Nyquist your square wave can become a perfect sine at 20kHz and nobody will hear the difference.
Full power square waves aren't even much of a torture test, since they give maximum efficiency (minimum output device dissipation) in *all* amplifier classes.

Too many misconceptions here to even address. Speed and clarity are correlated. An amp with sloped rise will run on causing blurring and dull sound which is commonly mistaken for warmth in the SS world.

 

[E-Stat]

Trying to translate: If "cold and austere" means "no added 2nd harmonic distortion or coloration, plain, simple, and severe", then that's describing the performance of an ideal amplifier.

70s era Crowns were horrible when run full range. Had a D150 as a teenager. Powerful, reliable but hard and closed in sounding. Nice amp for subs, but...

For me, characterized by high order harmonics given its use of first gen op amps, largely class B operation and dependence on lots of corrective feedback.

I've also owned one of their current switchers, an XLS1500. Very different character. Nice midrange, no hardness but no apparent extension and air at the top either. Uppermost harmonics hit a brick wall and die. A current Hypex Ncore fares better in that regard.

 

[twiiii]

Cold and austere rares its ugly head with issues like TIM distortion, etc, which Crown first stereo pre-amp had an over abundance of and the first DC 300 would go crazy and burn up. . PSA-2 was a great amp, it just couldn't be pushed in the high frequencies at lower impedances which generated a lot of distortion and is why I never used mine above 400 HZ. My DC-300 A's would go from ,o4 percent distortion at 9 KHZ at 250 watts into 4 ohms to over 10 % at the same level at 12 KHZ. Only the two Reference Crown amps were truly great Hifi amps putting out all the extra current you needed even down close to 2 ohms. Look at all the new amps, they have much higher distortion than the reference series and they don't have any. head room to speak of, neither does Crest, QSC and other commercial amps. Professionals realize the worse operating condition is when a compressed signal requiring an average of 1/8 power over a long haul can be the most detrimental to amplifiers and design the amps to be able to cope. Consumer amps rarely use more the 1/20 the power average, unless dealing with over processed pop or movie sound tracks. And then the subs which are normally self powered take most the abuse. Go listen to the differences between a Bryston and a Crown amp some time and throw in a Krell, it isn't a commercial amp, but try one. If you want to hear a great commercial amp you can listen to all day, try a Hafler. Upon first hearing one you will think some is missing but over the long haul you will find out what it is. Hearing fatigue.

 

[fill35u]

Too many misconceptions here to even address.

Of course. Feel free to reply when you can actually support your assertions.

Speed and clarity are correlated.

Please define "speed" and "clarity" as they apply to amplifiers?

An amp with sloped rise will run on causing blurring and dull sound which is commonly mistaken for warmth in the SS world.

You're confusing frequency response with ringing. Again, your square wave test is just an indicator of the properties of the output inductor and Zobel, which are after the negative feedback. Many amps have a damping resistor across the output inductor, this will reduce the "running on" you see from a square wave test- but none of this matters at audible frequencies.

Got any references to studies that show humans perceive ultrasound as "warmth"?

 

[SoCal Sam]

Of course. Feel free to reply when you can actually support your assertions.



Please define "speed" and "clarity" as they apply to amplifiers?



You're confusing frequency response with ringing. Again, your square wave test is just an indicator of the properties of the output inductor and Zobel, which are after the negative feedback. Many amps have a damping resistor across the output inductor, this will reduce the "running on" you see from a square wave test- but none of this matters at audible frequencies.

Got any references to studies that show humans perceive ultrasound as "warmth"?

Do you know what a square wave test is and how the results correlate to sound? Judging by your answer, no. Any departure from a square wave is technically distortion and that includes ringing which can been seen as the slight oscillation of the top of the plateau. Other "defects" are sloped rise, rounding, and tilting, all off which affect sound to varying degrees. To give latitude to all tastes in music, the terms defect and distortion are used only to show departure from the source square wave. Some distortion can be pleasant to the ears and therefore desirable.

 

[David_NC]

I have run Crowns and Yamaha also but I am now testing out a QSC RMX2450. its well known and not as old as some of the other pro amps I have used. I am also waiting on a QSC Powerlight amp which is some form of class D from QSC.

I have a couple QSC USA 900's which are older models with big transformers and lots of output transistors. This model has output limiting (similar to Power Guard), DC detection, and some other protections systems., which made me feel better about using them and not damaging speakers. I last used one of them on a pair of 4 ohm ADS M12's, and it's 400+ watts sounded really good. Right now, a friend has one of them with his Martin Logan somethings (I can't recall the models), and he reports that it sounds much better than his restored Hafler amp. These amps are quiet - in terms of output at idle and cooling fan, though I was able to hear the fan for a few minutes after a 112+dB 'test'. There was clearly no sound from the fan when it was playing that loudly. I'll end up using one bridged into 8 ohms for my upcoming Sonotube subwoofer for 800+ watts. I'd be curious how the 2450 works out.

 

[fill35u]

70s era Crowns were horrible when run full range. Had a D150 as a teenager. Powerful, reliable but hard and closed in sounding. Nice amp for subs, but...

What's "closed in"? I guess the opposite of "open, airy", whatever that means?

For me, characterized by high order harmonics given its use of first gen op amps, largely class B operation and dependence on lots of corrective feedback.

The uA739 wasn't first generation, not even among IC op amps. The designs advanced so rapidly, the first generation belongs only to the first - uA702. The uA739 had better performance than the ubiquitous uA741, although plastic cased versions used by Crown didn't fare well in that environment.

High(enough) feedback *reduces* higher order distortion. If there was inherently high distortion to the design, it would show up in the specs. Otala's flawed legacy dies hard!

And the DC150 isn't Class B, it's a proprietary scheme, "Class AB+B". The drivers provide current until the outputs kick in.

I've also owned one of their current switchers, an XLS1500. Very different character. Nice midrange, no hardness but no apparent extension and air at the top either. Uppermost harmonics hit a brick wall and die. A current Hypex Ncore fares better in that regard.

Might be a consequence of a particular load- simpler Class D has always had trouble with matching top end performance to a variety of loads.

 

[E-Stat]

What's "closed in"? I guess the opposite of "open, airy", whatever that means?

Two different concepts. The former indicates a lack of separation and soundstage width. The latter refers to HF transparency.

The uA739 wasn't first generation, not even among IC op amps.

Call it whatever you will. Op amp sound quality sucked in 1968.

High(enough) feedback *reduces* higher order distortion.

Nelson Pass certainly disagrees with you on that.

"Negative feedback can reduce the total quantity of distortion, but it adds new components on its own, and tempts the designer to use more cascaded gain stages in search of better numbers, accompanied by greater feedback frequency stability issues.

The resulting complexity creates distortion which is unlike the simple harmonics associated with musical instruments, and we see that these complex waves can gather to create the occasional tsunami of distortion, peaking at values far above those imagined by the distortion specifications."

And the DC150 isn't Class B, it's a proprietary scheme, "Class AB+B". The drivers provide current until the outputs kick in.

Hence, "largely" class B. It employed zero bias to the output stage. Poor sounding design.

Might be a consequence of a particular load- simpler Class D has always had trouble with matching top end performance to a variety of loads.

Whatever. A NAD 325BEE was markedly superior at the top driving New Advents. As is the Hypex Class D amp now used in the garage system.

 

[DaveVoorhis]

Do you know what a square wave test is and how the results correlate to sound? Judging by your answer, no. Any departure from a square wave is technically distortion and that includes ringing which can been seen as the slight oscillation of the top of the plateau.

A perfect square wave means infinite bandwidth, which is impossible.

If you're seeing what looks like a square wave at the output of an amplifier, you're viewing it at too slow of a sweep speed (assuming an oscilloscope) to see the slope of the "square" wave edges. It's never really a square wave, but its rise-time slope can be used to roughly compute the bandwidth of the amplifier. Measure how long it takes in nanoseconds to rise from 10% to 90% of its amplitude and multiply by (a conservative figure of) 0.35 to get the (rough) bandwidth in Hz. This is essentially treating the square wave waveform as a sine wave and extrapolating the frequency it must be to have a particular slope.

 

[SoCal Sam]

A perfect square wave means infinite bandwidth, which is impossible.

If you're seeing what looks like a square wave at the output of an amplifier, it's never really a square wave, but its rise-time slope can be used to roughly compute the bandwidth of the amplifier. Measure how long it takes to rise in nanoseconds from 10% to 90% of its amplitude and multiply by (a conservative figure of) 0.35 to get the (rough) bandwidth in Hz. This is essentially treating the square wave waveform as a sine wave and extrapolating the frequency it must be to have a particular slope.

Square wave test is used by the industry to compare sound reproduction. It is run 20-20kHz which is what really interests humans. My tech was a circuit designer and I sat in on at least a dozen tests of receivers, high powered amps, and tubes. 'Scope results can be heard at the speakers. Square waves are not sine waves. Sine waves are easy to generate and do not reveal how an amp will behave with a dynamic signal.

 

[fill35u]

Do you know what a square wave test is and how the results correlate to sound? Judging by your answer, no.

A square wave test is helpful for making sure gear meets specs, i.e. troubleshooting. As I pointed out, square wave performance of a functioning adequately designed amp has no bearing on sound. It reveals minor design and test setup differences that aren't audible. It does give the uneducated something to talk about, though.

Any departure from a square wave is technically distortion and that includes ringing which can been seen as the slight oscillation of the top of the plateau. Other "defects" are sloped rise, rounding, and tilting, all off which affect sound to varying degrees.

None of these things are audible if they are due to ultrasonic harmonics. Rise time is merely a function of frequency response, or rather slew rate if the signal is high enough. An amp only needs enough slew to achieve its power bandwidth. Even then, many amps have high frequency limiting to protect in case of oscillation (and not many high frequency drivers can withstand full power from most amps). The power spectral density of music drops like pink noise, so practically there's little need for power bandwidth to extend to the top. If you're triamping an array of compression drivers at full power, you might care. But otherwise your precious square wave rise time is meaningless.

Tilt of a (20Hz) square wave top/bottom is a useful test for low frequency rolloff. But it's a convenience, not some especially revealing trick.

You seem to be stuck on this idea that there's something special about square waves. They're just positive and negative step response tests. What you see in the time domain in the waveform on the scope is just frequency response illustrated in a different way. Oscillation (ringing) will show up with a high frequency sine wave input. Slew rate limiting that causes a slope will show up as THD-20. These are tests for *bad* amplifiers, not indicators for audible differences from *good* amplifiers.

*Bad* amps or amps used badly can sound different from good amps or each other. *Good* amps used properly sound the same- by definition.

To give latitude to all tastes in music, the terms defect and distortion are used only to show departure from the source square wave. Some distortion can be pleasant to the ears and therefore desirable.

It's anybody's prerogative to like whatever they want. But if you prefer imperfection, just don't call it "high fidelity".

 

[DaveVoorhis]

Square wave test is used by the industry to compare sound reproduction. It is run 20-20kHz which is what really interests humans. My tech was a circuit designer and I sat in on at least a dozen tests of receivers, high powered amps, and tubes. 'Scope results can be heard at the speakers. Square waves are not sine waves. Sine waves are easy to generate and do not reveal how an amp will behave with a dynamic signal.

Depending on the rise-time of the square wave, it will potentially have harmonic content way beyond the bandwidth of any input to the amplifier. That can provide a useful repair tool -- one channel ringing more than the other, or with a different rise-time might be indicative of problems -- but it's not of much use beyond that. THD is tested with a pure sine wave and measuring harmonic content at the output. Bandwidth (EDIT: and frequency response) is tested by sweeping a pure sine wave over a range of frequencies and measuring the amplitude.

 

[fill35u]

Two different concepts. The former indicates a lack of separation and soundstage width. The latter refers to HF transparency.

Thank you!
There's no excuse for a lack of channel separation, and in practice about 20dB is all that's needed. Hard to believe the DC150 couldn't achieve that.

Ok, what's "HF transparency"?

Call it whatever you will. Op amp sound quality sucked in 1968.

Then all albums mastered using op amps from that era anywhere in that chain must suck, too?

Got any proof that any particular op amp inherently sounds bad? Individual components don't have any sound, it's how they are used.

Nelson Pass certainly disagrees with you on that.

I'm fine with disagreeing with Pass, as he often points out he's "in the entertainment industry". I don't use gear to be entertained by it or its designer, I use gear to be entertained by the *music*.

"Negative feedback can reduce the total quantity of distortion, but it adds new components on its own, and tempts the designer to use more cascaded gain stages in search of better numbers, accompanied by greater feedback frequency stability issues.

The resulting complexity creates distortion which is unlike the simple harmonics associated with musical instruments, and we see that these complex waves can gather to create the occasional tsunami of distortion, peaking at values far above those imagined by the distortion specifications."

Pass deceptively doesn't show how his testing would have looked at 20dB or more of negative feedback, as the higher order distortion products would have been reduced. Hood's graph that he borrows clearly shows this. Pass goes on to reveal that his approach is just a preference, with no real argument to explain why.

None of this is meant to disparage any of Pass's designs. But there's a lot of hype going on.

The thing I've always found most fascinating about that article was his comment that, anecdotally, he has found that one third of people prefer some 2nd harmonic THD, a third prefer 3rd, and the last third prefer none at all.

Hence, "largely" class B. It employed zero bias to the output stage. Poor sounding design.

It's actually a clever idea, albeit tricky to pull off. It avoids the issue of thermal dynamic distortion from chasing the optimal bias point, which can indeed be an "elephant in the room" with poor sound from typical Class AB biasing schemes. Obviously I can't speak to your personal experience and impressions, though.

 

[fill35u]

Square waves are not sine waves.

Somebody needs to hit the books about the Fourier series.

 

[SoCal Sam]

A square wave test is helpful for making sure gear meets specs, i.e. troubleshooting. As I pointed out, square wave performance of a functioning adequately designed amp has no bearing on sound. It reveals minor design and test setup differences that aren't audible. It does give the uneducated something to talk about, though...

Sine wave is used for trouble shooting, not square wave. A properly function amp can show the "defects" that I mentioned in my previous post. An amp with a fault will in most cases be revealed as a defect in a sine wave.

...It's anybody's prerogative to like whatever they want. But if you prefer imperfection, just don't call it "high fidelity".

Hooray, we have common ground. In fact, it looks like you prefer objective accuracy.

 

[SoCal Sam]

Somebody needs to hit the books about the Fourier series.

A square wave is still not a sine wave as applied to audio. They do not sound the same and they are not applied the same. We will have to disagree on that. I'll go with the industry on this, not you.

 

[DaveVoorhis]

A square wave is still not a sine wave as applied to audio.

Every square wave is an added series of sine waves, whether applied to audio or not.

A "square" wave in audio is a troubleshooting and diagnostic tool. A sine wave in audio is a measuring tool.

 

[E-Stat]

Thank you!
There's no excuse for a lack of channel separation, and in practice about 20dB is all that's needed.

You're kidding, right?

Ok, what's "HF transparency"?

Quality of high frequency resolution.

Pass goes on to reveal that his approach is just a preference, with no real argument to explain why.

He hears what many others hear when it comes to reproducing live, unamplified music. And continues to design and build some of the highest sound quality amplifiers.

Then all albums mastered using op amps from that era anywhere in that chain must suck, too?

Decidedly less good than using discrete devices. Those like Robert and Wilma Cozart Fine clearly understood the value of the entire chain. The Living Presence Mercury recordings remain a reference today.

Got any proof that any particular op amp inherently sounds bad?

Do you have extended listening experience with either the D-150 or DC300A? Twiii and I heard the same lack of quality. The ICK preamp was far worse.

 

[fill35u]

You're kidding, right?

Under most situations, that's all you need. Or get. A great phono cartridge might get you 30dB... at 1kHz, and dropping from there. Some folks find *adding* crosstalk at higher frequencies helps imaging. There's of course the 10dB dip around 2kHz of the phantom center with two-speaker stereo due to the HRTF.

Quality of resolution

Ok, what's "quality of resolution"? That implies being to tell at least two things apart, what are they?

He hears what many others hear when it comes to reproducing live, unamplified music. And continues to design and build some of the highest sound quality amplifiers.

So... he agrees how 0.01% of all music sounds to some other folks?
And he makes amplifiers that are just as sonically neutral as the majority of amplifiers on the market?

Decidedly less good than using discrete devices. Those like Robert and Wilma Cozart Fine clearly understood the value of the entire chain. The Living Mercury recordings remain a reference today.

Coincidence is not correlation, nor causation. What the Fines understood isn't clear at all. That studio had a variety of new and used gear. IC op amps were still new and expensive in the late 60's, I wouldn't expect too many recording consoles would be designed with them. Especially with all the mic pre's necessary, high gain with low noise wasn't practical until later. But the input stage of a power amp is transconductance, it doesn't need that much gain, and you only need one chip.

Do you have extended listening experience with either the D-150 or DC300A? Twiii and I heard the same lack of quality. The ICK preamp was far worse.

No, but my experience would have no bearing (unless the speakers caught fire, which might be a concern given the lack of DC protection). @BMWCCA liked the sound of his D-150 just fine.

 

[BMWCCA]

https://audiokarma.org/forums/index...ir-generalization.831096/page-2#post-11809429

I replaced a Fisher SA1000 with a brand-new Crown D150 (pre-A, no faceplate version) back around 1972 paired with a McIntosh C20 running a pair of JBL 030 with the 075 ring-radiator many claim to be harsh and beamy. I enjoyed these for a decade before replacing the Crown with a D150A-II and moving the D150 to a new pair of L112s around 1982 where it still resides today sounding fine with the 044 tweeters and the C20. Eventually I replaced the D150A-II with a DC300A-II and now run PS200 and PS400 biamped with JBL 4345s with the ultra-high-frequency 2405 drivers. None of these sound "dreadful" but to the contrary all have been very musical while remaining revealing on bad recordings, and maybe that's what "dreadful" implies. I have no experience with the newer "lightweight" Crowns. I'm old and quite satisfied with the D-type amps and their ilk.

I've often said it before but when I purchased my first Crown, my dealer was a McIntosh and JBL dealer (among other brands) who happily compared Crown to the Mac amps and even invited me to bring my Crown to the Mac Clinics where Dave O'Brien commented on the lack of distortion exhibited by the Crown even when driven beyond its rated power capacity. Granted, everyone's experience (and ears) are different, and this is just to reaffirm my satisfaction with Crown in answer to the topic of this thread.[quote/]