[swannie007]

Arrrr....The Boson from the Bush! I always get a big smile when you report in Swannie.

Just letting my Captain know that I am still alive and well. Stole some time from preparing a lecture for my students that I will deliver tomorrow. I am a teacher at a local community college having retired from the tools as an instrumentation and controls technician for about 40 years. Time to pass the knowledge base on to the next generation.
Take care my friend and continue to captain the good ship SS Gustard in good health and spirits.

 

[spaech]

I've been switching back and forth between the H10 and the Valhalla, and noticing the distinct tubey shimmer & sparkle in the top end with the Valhalla which is entirely absent in the H10. Which is expected, but I was trying to quantify what exactly is happening to the waveform that makes the tube amp less neutral? Longer attack and decay? Resonance?

 

[DDDamian]

  I've been switching back and forth between the H10 and the Valhalla, and noticing the distinct tubey shimmer & sparkle in the top end with the Valhalla which is entirely absent in the H10. Which is expected, but I was trying to quantify what exactly is happening to the waveform that makes the tube amp less neutral? Longer attack and decay? Resonance?

I think it just filters some of the highs that give you that air and sparkle. All audio gear has (at it's most basic) resistor-capacitor (R-C) filters to constrain the bandwidth to the audio spectrum. This is known as a low-pass filter. The H10 seems to have a fair roll-off up in that high-end. This results in a warmer, smoother, less-fatiguing sound at the expense of air and treble detail.

 

[spaech]

  I think it just filters some of the highs that give you that air and sparkle. All audio gear has (at it's most basic) resistor-capacitor (R-C) filters to constrain the bandwidth to the audio spectrum. This is known as a low-pass filter. The H10 seems to have a fair roll-off up in that high-end. This results in a warmer, smoother, less-fatiguing sound at the expense of air and treble detail.

The H10 sounds detailed but neutral in the highs, it doesn't sound at all rolled off to me. Whereas the Valhalla has this chime-like shimmer to the highs. I'd have thought any low pass filters in the SS amp would only affect frequencies well outside the range of human hearing? But I don't know enough about how the electronics work. I hate these ambiguous metaphors when describing sonic qualities so I'm trying to nail down what the tubes are doing to the sound in objective terms.
 
Perhaps it's this ringing effect that tube amps apparently suffer from in various degrees:
 

 
I guess you could call it a feature rather than a bug. It's not unpleasant -- quite musical, but it does seem to be an added quality that the tube amp colours the sound with, not present in the recording.

 

[DDDamian]

  The H10 sounds detailed but neutral in the highs, it doesn't sound at all rolled off to me. Whereas the Valhalla has this chime-like shimmer to the highs. I'd have thought any low pass filters in the SS amp would only affect frequencies well outside the range of human hearing? 

Out of four amps (2x tube, 2x SS) on my desk right now, plus three Fiio portable players, the H-10 is by far the warmest of the bunch. IMO it has very rolled-off (or more likely shelved) highs. It even seems to tame the upper frequencies of the HD-800 and HE-400's - two cans known to have a little more energy up top. I usually use it paired with them. For something already a bit warm like the HD-650 I find it goes too far in reducing treble. That's been my experience with it anyways.
 
And sure, the circuitry should amplify in a neutral way all the way through to 20kHZ or so, but subjectively most don't. It'd be unusual to see a "brick-wall" filter in an amp - some roll-off is normal in any filter - it's the slope/curve of it and the starting point that define what gets through. Though I mention R-C circuits there are also other components that act as filters like transformers, chokes, etc.
 
For sure tubes can add ringing, filtering and other characteristics to the sound - often in very nice ways. Part of the fun with tube-rolling!

 

[stuartmc]

  Out of four amps (2x tube, 2x SS) on my desk right now, plus three Fiio portable players, the H-10 is by far the warmest of the bunch. IMO it has very rolled-off (or more likely shelved) highs. It even seems to tame the upper frequencies of the HD-800 and HE-400's - two cans known to have a little more energy up top. I usually use it paired with them. For something already a bit warm like the HD-650 I find it goes too far in reducing treble. That's been my experience with it anyways.
 
And sure, the circuitry should amplify in a neutral way all the way through to 20kHZ or so, but subjectively most don't. It'd be unusual to see a "brick-wall" filter in an amp - some roll-off is normal in any filter - it's the slope/curve of it and the starting point that define what gets through. Though I mention R-C circuits there are also other components that act as filters like transformers, chokes, etc.
 
For sure tubes can add ringing, filtering and other characteristics to the sound - often in very nice ways. Part of the fun with tube-rolling!

I would agree that the stock H10 has a warm, almost "tubey" sound for a solid state amp.  My op-amp "swabbing" has led me to the conclusion that it is more the character of the chosen op-amps than it is a filtered limitation of high frequencies. The AD797 and AD823 combination is very neutral with a lot of top end detail as compared to the stock opa123 and 5532.

 

[spaech]

  Out of four amps (2x tube, 2x SS) on my desk right now, plus three Fiio portable players, the H-10 is by far the warmest of the bunch. IMO it has very rolled-off (or more likely shelved) highs. It even seems to tame the upper frequencies of the HD-800 and HE-400's - two cans known to have a little more energy up top. I usually use it paired with them. For something already a bit warm like the HD-650 I find it goes too far in reducing treble. That's been my experience with it anyways.
 
And sure, the circuitry should amplify in a neutral way all the way through to 20kHZ or so, but subjectively most don't. It'd be unusual to see a "brick-wall" filter in an amp - some roll-off is normal in any filter - it's the slope/curve of it and the starting point that define what gets through. Though I mention R-C circuits there are also other components that act as filters like transformers, chokes, etc.
 
For sure tubes can add ringing, filtering and other characteristics to the sound - often in very nice ways. Part of the fun with tube-rolling!

I wonder if artifacts / distortions like overshoot and ringing will add to the total energy in the higher frequencies, or the perception of it. If the H10 is producing a clean signal without much in the way of these artifacts, and providing enough current to clamp the drivers tight to the waveform without deviation, that might be why it seems darker in comparison. Just speculating here, but it seems plausible that a powerful and neutral amp with low THD might seem darker in comparison. Looking at the specs, the Valhalla has "THD Less than 0.5%, 20Hz-20KHz, at 1V", whereas the Gustard has "THD + N (1kHz 1W @ 100ohm): <0.00035%". Seems like a big difference.

 

[spaech]

Just reading about it a little more, supposedly most amps are designed to produce a "ruler flat" frequency response in the range of human hearing, but that's only if the output impedance is constant. Since headphones with dynamic drivers are far from constant in their impedance over the frequency range, that would provide a plausible explanation for significant differences in the sonic signature between amps.
 
So for instance, according to the graphs here, the HD800's impedance drops by nearly half between 200hz and 1000hz, and stays around 350ish ohms up to 10khz. So let's say we have an amp that has a high variation in output over that impedance range -- it's going to sound brighter than an amp that has less variation over the same impedance range. Which is perhaps suggesting the Gustard is more consistent with its output between 300 ohms and 600 ohms, compared to other amps.

 

[mandrake50]

  I think it just filters some of the highs that give you that air and sparkle. All audio gear has (at it's most basic) resistor-capacitor (R-C) filters to constrain the bandwidth to the audio spectrum. This is known as a low-pass filter. The H10 seems to have a fair roll-off up in that high-end. This results in a warmer, smoother, less-fatiguing sound at the expense of air and treble detail.

The spec for the H10 is
Frequency response: 0-55kHz (-0.5dB).
Believe it, I had mine at a friends with some test gear. At 1 watt into 100 ohms (purely resistive), it looked extremely flat to 50K and well beyond. There is no filtering going on in the audible range.
People like tube sound, as do I, but what the  tubes  "add" to the sound is distortion pure and simple. It may be distortion that is pleasing to the ear, but it is distortion just the same.
 
The varying impedance question. The load does shape the output to some extents. The Amp and drivers have a sort of symbiotic relationship. I have heard many times how much people favor the H10 with planar headphones. I wonder how much of that is due to their pretty much flat impedance curve over the audio range?

 

[DDDamian]

Currently running with two OPA2604 and two AD797AN op-amps - have a few more to try.
 
It's hard to subjectively judge whether an amp is neutral - I can only compare to all the others I have, and regardless of HP the H-10 sounds warmer. Whether it's the op-amps or other components I don't really know, but bright cans sound good, and very warm cans too warm, so the amp is the common factor in my listening experiences with it.
 
Not slagging it for it. Quite the opposite: I would've ditched the HE-400's until I tried that pairing. Another tool in the kit. Kinda like how the 650 is a great relaxing can, the H-10 has a similar effect compared to ones with a bit more high-end emphasis. Note I did not say neutrality there lol.

 

[DDDamian]

  The spec for the H10 is
Frequency response: 0-55kHz (-0.5dB).
Believe it, I had mine at a friends with some test gear. At 1 watt into 100 ohms, it looked extremely flat to 50K. There is no filtering going on in the audible range.
People like tube sound, as do I, but what the  tubes  "add" to the sound is distortion pure and simple. It may be distortion that is pleasing to the ear, but it is distortion just the same.

I knew that was coming lol - or that someone would pull out a graph. Compare it to the BHA-1 which is also razor-flat in the serialized graphs they supply with each unit (and made in Canada at about four times the price) . The H-10 sounds substantially warmer with any given can. Which one's right?

 

[mandrake50]

  I knew that was coming lol - or that someone would pull out a graph. Compare it to the BHA-1 which is also razor-flat in the serialized graphs they supply with each unit (and made in Canada at about four times the price) . The H-10 sounds substantially warmer with any given can. Which one's right?

There is not "right"  as to the sound... it is what it is, but the question was ...or statement was about some level of filtering that might be responsible for the sound differences between the H10 and the Schiit. Valhalla.
 
 
I am not going to tell anyone that I have the answers to why amps sound different. We all know that they do. Apparently attributing it to FR curves is not all there is to the equation. That is the only point that I was trying to make.
In addition to the tubes adding coloration, that is.

 

[DDDamian]

  There is not "right"  as to the sound... it is what it is, but the question was ...or statement was about some level of filtering that might be responsible for the sound differences between the H10 and the Schiit. Valhalla.
 
 
I am not going to tell anyone that I have the answers to why amps sound different. We all know that they do. Apparently attributing it to FR curves is not all there is to the equation. That is the only point that I was trying to make.
In addition to the tubes adding coloration, that is.

I don't have the answer either
 
I know just about every audio device out there (speakers, amps, whatever) claims incredible linearity - you would think they all sound exactly the same lol. Especially SS amps where there's no moving drivers or anything. I can see things like slew rates affecting sound in tubes and the like, but op-amps have slew rates that are way past audibility so that can't really be a factor either. Either someone's lying about the FR graphs / stats or there's some deeper mystery here. If the FR's are flat then the transient response is about all I can think of when comparing with the same can (along with impedance swings in the can and the amps reaction to it). I think we're basically agreeing
 
I totally agree that what a tube brings is colouration or distortion. Some love it, some don't and ofc every tube has a different sound, even within the same types and makes. Some have made me go ugh - too dull or too coloured. Some are just amazing.
 
Great hobby isn't it? 

 

 

[spaech]

So this little exercise in excel was an attempt to quantify how these two amps (bha-1 and h10) might differ in terms of power output across the frequency range for the HD800s. And therefore, whether we could expect one to sound darker/brighter than the other based on relative power output across the spectrum. I had to make a few extrapolations due to limited data for the H10. If the Gustard does indeed sound darker than the BHA-1, then I've either messed something up in this analysis or there's something else at play.
 
 

 

[DDDamian]

Wow - that was quick. But how does the power at 1Khz (the usual reference point) into the given load (300ohms) translate across the whole spectrum? I.e. what if at 300ohms one amp puts out xxma but at 5khz puts out yyma into the same load? Think that's more the question. You're extrapolating based on the one data point (power at 1kHz) and assuming it's flat right on through the rest of the spectrum. That's not what most are finding when the describe the H-10 as warm and detailed, and the BHA-1 as on the brighter side.