Frequency response graphs will only depict linear distortion; non-linear types of distortion (harmonic and IM) won't affect the FR graph at all.

Strictly speaking, you're right, virtually no piece of modern solid state gear should have any audible differences from any other piece of modern solid state gear, since the distortion levels are vanishingly small. But of course things don't seem to work out that way. (Life would be much simpler if they did!) From their specs, every op-amp should sound identical, but I haven't met anyone yet, even non-audiophiles, who couldn't tell the differences between even two op-amps. The little things do seem to make a difference.

I don't find Ray's amps to be rolled off in the highs at all. And if you do, you have the option of swapping op-amps to season to taste.

As for "bloated midrange" of HR-2, I strongly disagree. Many solid state devices just don't do midrange, and this is why many people prefer tubes. HR-2 has a very full and realistic middle (for a solid-state amp), sounds emerge like they are supposed to, they aren't muddy, restrained, closed-in, and vague or hazy. All the life and soul of the music is in the midrange. Midrange is not supposed to be exactly 1/3rd of the whole picture. Midrange is more like 2/3rds of the whole picture. If treble, bass and midrange sound evenly distributed and proportional, IMO, that amp is deficient in the middle and lacking body and life.

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!

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Interesting. Do all (non super-cheap crap) op amps measure the same in all aspects tested by RMAA, including THD+N and IMD? Has anyone measured this? I think morsel and Fixup measure their projects with RMAA, would like to hear more on this...

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Yes and no. They're all basically in the same ballpark. Noise varies a little. Distortion profiles vary a little. PSRR varies. Back when Iron_Dreamer was modding computer sound cards, he generally did a good job of doing before/after RMAA plots. He probably still has them around. You should send him a PM.

Sound varies considerably though, independent of the measurements.

A highly knowledgeable and reasonable subjectivist. Just what I need to keep my head-fi interesting.

Of course I disagree with your last statement. It's part of my religion.

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I was wondering when someone would mention the op amps used (Thanks Markl).

Both the PPA and HR-2 (also XP-7) allow you to change op amps. Some of the characteristics mentioned, such as, mid & treble impacts are definitely affected by these. While one could use the stock Emmelines as a reference they would have to state the op amp used in the PPA to make a comparison meaningful. Note I'm not saying to prove one is better or worse than the other for a particular individual ... just to make a comparison that makes sense.

The effects of different op amps from AD8610, AD8065, AD797, OPA134, OPA604, ..., OPA627/637, etc do make a noticable difference in "both" families of amps. Therefore, while one can prefer one or the other version of either headamp, it is not logical to make definitive statements about the amps in general unless you identify all the relevant factors. For example, one HR-2 might be preferred to another HR-2 (similarly between two PPA's) depending on the op amps in them.

Back to listening to the music ... Gord SW Ont.

Duh, am I to understand that SR-71 "rolls off" high freq. in a way that is unmeasurable/(or at least beyond common equipement resolution), yet this roll off is still audible (to others) ?

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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

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This is all relative to other amps. Gilmore V2 and Lite sound awesome when they are done right. The headamp lite is stunning. The headamp V2-SE is a bit dry but not too bad. The PPA on the other hand is sterile.


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Coloration is muddy water - we have no way of knowing if an amplifier is coloring the sound or not because we have no way of telling how the source behaves.

However I can assure you that myself and other trained ears have done extensive AB between Emmeline, Singlepower, Woo Audio, Eddy Current amplifiers and found that they sound almost the same - especially the Emmeline and Singlepower amps - very hard to tell the difference for many of us and impossible for most

So - I have personally heard this - Even the Gilmore's are hard to tell apart from the Emmeline counterparts.

My inference is that they are all very close and true to the source since they sound the same. The differences in the soundstage, speed and precise response at different areas of the spectrum (markedly the bass spectrum) is what allows you to positively ID one amp from the other in an AB test.

Now - the point I am trying to make is - all these people at the meet - did not hear any rolloff, midrange bloating (I will not use the word coloration - if someone else does then I will launch another debate about this ). If Emmeline had it - so did all the other amps because they were honestly VERY VERY hard to differentiate from each other.

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For me the A/B method works fine for me. The luxury of doing the 2-3 weeks method is something I usually couldn't make enough time for. I'm pretty discriminating in my audio and know what I like fairly quickly and it's served me well. Then again if someone wants to send me their Stealth for say 8 or 9 months I think I can properly review it!

AB testing works fine for me as well. The first time I hear an amp I establish its tonality. I usually start with a higher volume than normal and then scale down once I know what I am hearing so that the finer details filter through.

AB is where it is at and I am talking about spending at least 30 - 60 minutes on the AB test for reliable results. This is what I did at the meet.

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...

Biggie.

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I wish all of us would talk and describe our experiences the same way
Simple straightforward and to the point. well put archos.
That is how I go when something is playing the music.
the A-B method of 2-3 weeks is something I have only performed in about 3 different cases. other than that, it is pretty easy to pointout what the differences are.
Still, it is harder to put in a meet condition what the signatures are especially with Open headphones. what with all the noise around you and excited buzzing going on upon seeing new equipment, you knwow

I think the only way to know a certain piece of gear is to have it for a couple weeks or more. You, or at least I, really need that time to grow indifferent to that particular piece of gear, and it's there to simply play music; and that's when I can really identify it's traits. It's pretty easy to 'imagine' things when you're looking hard to define differences between pieces in a short time period. It's much easier when you're in the comfort of your home and listening at your leasure for indefinite amount of time.