[TrevorNetwork]

Quote:

Gord told me that with the opa627 in, it does not occur. I didn't get to compare though...

In my experience the OPA627/637 tend to have rolled off highs. I do find them generally pleasant sounding however.

To all those wondering about my amplifier preferences, I prefer to hear exactly what the source is putting out. I use a KG Dynahi. If you want to hear exactly what's there, it is the only way to go. Alternatively, the Headamp Gilmores are quite nice as well. I utilize a Benchmark DAC1 as a source. The DAC1 is known to be true to the source medium as well. If one desires to hear exactly what's there, again, the DAC1 is the one.

I am confident in saying that my setup is of reference quality, and I would gladly put it up against -any- headphone setup for resolution. I consider all tonal change performed by the amplifier / cables / source to be colouration. I consider tonal change performed by the headphones to be flavour. I do not mind changing the flavour at times. What arrives at the headphones should be exactly what the studio engineer recorded.

 

[Dane]

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Originally Posted by ampgalore The high frequency noise should either be there or not, and that high frequency IS present in the source. Ray Sammuels' amps did not reproduce those high frequency noise. Other amps did. This is a fact, not an opinion.

Concluding anything on high frequency roll-off based on whether or not there are niose artifacts in the signal chain and component interaction seems highly questionable to me. Noise is not something that's there to be reproduced, it's something to be avoided by proper grounding etc. This is all backwards - you may well have turned down the pretty girl

Also, AFAIK noise/hiss is made up off both low and high frequencies.

 

[GainHead]

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Originally Posted by gaboo Trouble is we don't know what op amps SR-71 uses, except for the red nail polish. Oh, wait, that is coloring the sound

Yes, we do. It is the AD8610 and BUF634. See here: http://headwize.com/ubb/showpage.php?fnum=3&tid=5276

 

[TrevorNetwork]

Dane:

What you're saying makes absolutely no sense. The source was producing noise that is added to the output signal. An amplifier's job is to amplify whatever it is fed via its inputs. RS amps do not "filter" the noise. In fact, it would be damn near impossible for an amplifier to make a decision on what was noise, and what was signal coming from the source.

 

[gsferrari]

No - thats what that dude "thinks" he knows.

Sad the way some people behave though...I have internal pics of PIMETA and SR-71 if you are curious and want a peek...I also know the differences between the SR-71 and the MINT, META-42, PIMETA...

Besides - there is only SO MUCH you can do with op-amps. Whatever CMOY did was there in the data-sheets...nothing special or incredibly innovative. That he did it is great news because it sure has taken things in DIY a long way but - it is nothing special, cannot be patented because the data-sheets with this information are already property of the manufacturers for these op-amps.

Ray uses resistors specified as "optimal" in the data-sheets. No fancy black gate stuff here...with reason. Why dont you guys send him a PM and ask him for his opinion - he will happily tell you what is going on in his amps and why he chose certain components over others.

I had this conversation with him a few days back and I think you should do the same.

 

[gsferrari]

Quote:

Originally Posted by TrevorNetwork Dane: What you're saying makes absolutely no sense. The source was producing noise that is added to the output signal. An amplifier's job is to amplify whatever it is fed via its inputs. RS amps do not "filter" the noise. In fact, it would be damn near impossible for an amplifier to make a decision on what was noise, and what was signal coming from the source.

So can you explain why they are rolled-off in the treble spectrum?

The amp cannot filter the noise
It has to amplify the noise
But there is no noise

It is a MINT according to some people - a MINT should amplify the noise - but this "mint copy" amp doesnt amplify the noise.

The noise is usualy a hiss resulting from a bad ground. perhaps the SR-71 ground took care of this unlike the other amps ampgalore used. Improper grounding in his "other" amps is also a possible explanation for this phenomenon.

But we are not talking about noise - we are talking about high frequency roll-off and noise includes a variety of frequencies - bass/mids/highs and everything in between.

I just want an explanation - theoretical - as to why this is happening with ALL of Ray's amps. Surely he is not stupid enough to let these amps out into the market like this? Surely me, archosman (professional AV specialist with excellent ears...better than mine) and others would have noted it?

Its just too bizarre to believe what you guys are saying because I clearly dont experience what you seem to be experiencing...

 

[markl]

Quote:

To all those wondering about my amplifier preferences, I prefer to hear exactly what the source is putting out. I use a KG Dynahi. If you want to hear exactly what's there, it is the only way to go. Alternatively, the Headamp Gilmores are quite nice as well. I utilize a Benchmark DAC1 as a source. The DAC1 is known to be true to the source medium as well. If one desires to hear exactly what's there, again, the DAC1 is the one.

"Neutrality" is a chimera. One man's "neutral" is another man's "colored". Things that measure identically sound different. No one knows "what's there", only what each piece of equipment is showing them. Everything in the signal path imposes it's own signature on the sound, as you know. You state "the DAC1 is known to be true to the source medium"-- how exactly? From other people's *subjective impressions* and your *subjective impression* of it, of course.

In one sense, though, we're all pursuing "neutrality"; we pick those pieces of gear that sound "right" to us. We wouldn't choose something that didn't sound "right" or had some obvious anomolies. Since we all assemble completely different systems to meet our needs, it's clear that each of us has a very different idea of what sounds "right".

And don't forget about the subject of "synergy" too, as different components will sound better or worse in conjunction with different gear, as we all also know. When someone says "Component A is very neutral and accurate", as if its some objective fact, it makes me chuckle. Neutral and accurate "*to you*", and "*in your system*".

 

[Dane]

Quote:

Originally Posted by TrevorNetwork Dane: What you're saying makes absolutely no sense.

OK.
Quote:

Originally Posted by TrevorNetwork The source was producing noise that is added to the output signal. An amplifier's job is to amplify whatever it is fed via its inputs. RS amps do not "filter" the noise. In fact, it would be damn near impossible for an amplifier to make a decision on what was noise, and what was signal coming from the source.

How was it verified that the source itself was producing the noise and that it wasn't a ground issue etc. that the other amps were unable to suppres or perhaps even contributed in creating?

Also, was it a hiss-like noise (which AFAIK isn't specifically high frequency) or was it really a very high pitched whine?

Example: When my Talisman is powered by my outlet in another room there is a weird interaction between it and my old Marantz CD player - the player seem to inject noise into the Talisman. When using my battery powered Larocco PR this noise isn't there. By your logic I should then conclude that my PR has rolled-off highs compared to my Talisman. This is absurd, if anything it's quite the opposite.

I suggest using a test CD instead of electrical noise to judge stuff like this.

 

[Gord SW Ont]

Quote:

Posted by Biggie: I found the hr-2 to have rolled off highs with the stock opamp. Gord told me that with the opa627 in, it does not occur. I didn't get to compare though...

Actually the highs in the OPA627 are not as rolled off as the AD797 to my ears. On the other hand they are not as emphasized as the AD8065 or 8610 for example.

As to which one is correct/neutral ... that probably depends on the individual, their audio experience, their hearing, etc???

Again in my opinion many of these discussions aren't making a whole lotta sense when people state these things as absolutes.

 

[Steve999]

Noise is not so simple, and I find it rather interesting.

Here, I did a quick google search, this stuff looks pretty good:

http://www.gcaudio.com/resources/how...stemnoise.html

http://www.epanorama.net/documents/g...erhumming.html

 

[markl]

I think there's another possibility re: hiss.

IMO, one of the things that the HR-2 does really really well, and leapt out at me, as I've commented on numerous times in my review(s) is its remarkable ability to portray subtle shades of volume. It has a full dynamic range, quiet sounds stay quiet, loud sounds stay loud.

Tape hiss is a small low-volume sound. It's possible that the other amps being compared to the HR-2 are *compressing* the sound, boosting low-level sounds up to a more audible level. Think of modern remastered Cds from analog tapes. They are heavily compressed and volume maximized, and the tape hiss is many dbs louder than it would be from a normal flat transfer. The dynamic range is compressed, the distance between the quietest sounds on the CDs and the loudest sounds is greatly reduced. Many people when hearing modern compressed CDs often say they sound "bright", confusing their loudness and forward nature with "brightness".

Since Ray's HR-2 is not compressing the signal, it may therefore sound "dark" relative to other amps, where other amps are compressing the signal, boosting tape hiss and making it more audible, and coming across as "brighter" than the HR-2. Some people may like the compression effect, and prefer the "brighter" more maximized sound.

Is this what is happening here? I don't know, but it's another possibility. Here's a snippet from my review of the HR-2 (I was the first to hear it, this review is from middle of last year). Should prove amusing and relevant to this discussion, as I definitely noticed this phenomenon:

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WHERE’S THE TAPE HISS? One of the most bizarre attributes of the HR-2 is its seeming suppression of the sound of tape hiss on analog recordings. Where does it go? With The Emmeline, I am much less aware that I’m listening to a recording, and feel more like I’m witnessing an event. Somehow, in the Emmeline’s presentation of this amazing soundfield, tape hiss becomes much less pronounced. It’s like the amp is pulling so much information off the master tape that the small matter of tape hiss is muted somewhat in relation to the music which is blooming all over the place. I suspect this all has to do with the Emmeline’s fantastic ability to distinguish between loud and soft sounds. It doesn’t compact everything into a narrow band, shoring off dynamic peaks and boosting low-level info to a similar plane as the music. I also believe that the ability to play soft sounds soft and loud sounds loud contributes to the sense that everything has been mixed and mastered correctly that I spoke of a moment ago. I think this quality of being able to accurately portray subtle shadings in volume can be as important to good sound reproduction as the ability to reveal subtle shades of tone and timbre, yet is often overlooked. In any case, when you hear this amp, you’ll see that suppression of tape hiss does not mean the amp is truncating sound or has a high noise floor. With the AD797 this amp extends forever in all directions, is dead quiet, very detailed and extremely “vivid”.

And besides, do you listen to music for the tape hiss, or for the music?

 

[Born2bwire]

Quote:

Originally Posted by TrevorNetwork Dane: What you're saying makes absolutely no sense. The source was producing noise that is added to the output signal. An amplifier's job is to amplify whatever it is fed via its inputs. RS amps do not "filter" the noise. In fact, it would be damn near impossible for an amplifier to make a decision on what was noise, and what was signal coming from the source.

I think what he's getting at and what some have suggested is that if ampgalore was hearing some hiss or noise that's present in the original recording, then the noise would be made up of a range of low to high frequencies. If the SR-71 was attenuating the high frequencies, then parts of the noise should still be present. In fact, since we're much less sensitive to the high frequencies, the noise should not appear to be greatly attenuated and at it's most extreme would reduce to a low frequency hum. So this isn't a good line of reasoning to support the idea of high frequency roll off, in the end it justs seems to be up to the tastes of the listener.

 

[Dane]

Just did some Googling and I found that tape hiss does indeed contain many frequencies:

http://peufeu.free.fr/audio/extremis...ackground.html

"If the noise is quite white, its energy being spread all around the frequency spectrum (like tape hiss)..."

So, if the noise you heard resembled anything like tape hiss, I'm afraid the "no noise => high-frequency roll-off" theory falls.

 

[archosman]

Quote:

Originally Posted by markl ...I sometimes think people try to pick the gear that they will enjoy the least. If *anything* makes you emote or respond, there must be something "wrong" with the device. It must be "colored" somehow if I am enjoying it and feeling it. Therefore I try to pick the most clinical, detached, sterile and lifeless piece I can find for the sake of "neutrality". Nothing must stick out so I don't notice anything, it just sits there as dead as dead as could be. Ahhhhhh..... sweet netrality....zzzzzzzzzzzzzzzzzzzzzzz...... So many high-end devices are voiced this way, bland, bland, bland, distant and hazy and dull. Not for me!

That's kind of the way I feel about my RKV. It seems kind of lifeless there. I do need to spend some more time with it....

 

[GainHead]

Quote:

Originally Posted by gsferrari No - thats what that dude "thinks" he knows.

RS had an opportunity to deny the claim and he did not, so that is a fairly good indicator that the AD8610/BUF634 combination is correct.

Other factors also indicate this combination is correct. RS admitted the SR-71 uses a buffer. What other buffer besides the BUF634 are you aware of that he could be using? Also, the SR-71 reportedly can last up to 60 hours with alkaline batteries according to RS. At best you get about 340mA from two 9 volt alkalines. Assuming just quiescent current and full battery drain, what other combination of buffer and op-amp could possibly last this long?