[JaZZ]

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Originally Posted by Prog Rock Man /img/forum/go_quote.gif Of the two cables I have made I have the volume at between 9 and 10, rather than the stock cable's 9 maximum.

Do you have an ohmmeter at your disposal?
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[JaZZ]

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Originally Posted by aimlink /img/forum/go_quote.gif They sound great...

I'm sure they do.

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They're spartan in appearance yes, and like cables and other audio equipment, their spartan appearance has the opposite effect with regard to expectations.

You mean they sound better than you would expect? Now if that's not a clear disproof of the placebo effect!

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[Head Injury]

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Originally Posted by JaZZ /img/forum/go_quote.gif You mean they sound better than you would expect? Now if that's not a clear disproof of the placebo effect! .

Actually...

If you pay a lot of money for something that looks like a piece of crap, it's reasonable to think that your expectations of the sound will be even higher

 

[aimlink]

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Originally Posted by Head Injury /img/forum/go_quote.gif Actually... If you pay a lot of money for something that looks like a piece of crap, it's reasonable to think that your expectations of the sound will be even higher

The Ugly Duckling. Haha!

 

[Shike]

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Originally Posted by JaZZ /img/forum/go_quote.gif So in which respect was I wrong? It would be more productive if you could offer your version instead of speaking in riddles.

You're making it sound like I assume all amps sound the same - regardless of anything.

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I think you're trying to nebulize the discussion. Those were tube amps, as you may remember. And we don't know their measuring specs. Apart from that they were reported to sound excellent nonetheless. But let's not lose track!

The point is it was screwed circuitry that caused an issue, and didn't show till someone measured and actually opened the box up to find crap quite frankly.

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I'm so quick because I'm 100% sure that those HeadRoom amps can drive the HD 650 and the HD 800 and the T1...

Evidence? Or are you a hundred percent assuming too?

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And litterally every solid-state headphone amps I've tried has smoothly driven all headphones I've attached to them. The amp you're speaking of must be an exotic.

An exotic? Hardly . . . have you not heard of AMB Labs? The Mini^3 only goes to 300ohms, while the M^3 is much more capable.

Not all amps are equivalent or made for all loads. On the other hand I don't think it's particularly expensive accomplishing good amp design either, and gets blown out of proportion too.

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So far you haven't addressed absolute numbers. Which data would you consider above the hearing threshold?

That's rather vague - in terms of a question. The numbers they provide only tell so much. What's the THD of the amp at 16ohms and 650ohms? Are we to assume it's impervious to different loads for no reason?

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I don't think it applies to the published HeadRoom specs, do you? What other criteria would you consider important, e.g. what IMD numbers are you expecting to come into play to save the hierarchy among HeadRoom's line-up? Or which output impedances are there implanted into the cheaper models to make them sound cheaper?

I'm not implying anything unlike you. I hope Headroom wouldn't sabotage one of their own products to create an artificial tier. Again though, I'm not going to assume one way or the other like you seem to.

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And a general question: Do you hear sonic differences with different amps?

Depends if they reach levels that are measurably inaudible and don't cause problems with the transducers. If we can talk about speaker amps for a moment, if I hooked my Magnepans to an old 5.1 receiver it would surely burn up and sound awful. While it may not be as dramatic with headphones there's no doubt that something such as clipping will cause distortion.

All of the amps I've purchased meet the needs of my headphones, so I really can't tell a difference. The only time I could tell a difference is when the ground opamp on the Mini^3 was going shot.

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Have you auditioned a HeadRoom amp or two? – I haven't, but would like to (and I'm sure they sound good, although they're ugly).

You keep saying "I'm sure", but you haven't even touched one. They may be great amps, but headroom doesn't provide enough information for anyone to be sure.

And all of this doesn't take into subjective taste - such as people that use high distorting tubes or force them into clipping (not talking about low distortion designs, though they may have their own problem).

 

[Prog Rock Man]

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Originally Posted by JaZZ /img/forum/go_quote.gif Do you have an ohmmeter at your disposal? .

Well I have a multimeter and so far I have only learned how to us it to check continuity. I did think myself that cable resistance and some for of attenuation is going on. This is day two of the new cable and day one of some new ICs I made. I can now listen with the volume from 8 to 12. Even 7 and 1 are do-able without 7 being a total loss of sound and at 1 there is still no clipping or distortion. But it feels too loud for my ears.

 

[JaZZ]

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Originally Posted by Shike /img/forum/go_quote.gif You're making it sound like I assume all amps sound the same - regardless of anything.

Yes, I did. But that was just a working hypothesis to have a starting point. You have the opportunity to correct it anytime.

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Evidence? Or are you a hundred percent assuming too?

100% assuming, too. I take it from the reviews I've read about the good synergy between HeadRoom amps and the 300-Ω Sennheisers. So I'm indeed 100% sure that HeadRoom amps can drive 300-Ω headphones. And 600-Ω headphones as well.

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An exotic? Hardly . . . have you not heard of AMB Labs? The Mini^3 only goes to 300ohms, while the M^3 is much more capable.

No, I don't know this company, but I've heard of the M^3. The Mini^3 apparently is an exception among headphone amps. A budget model, as it seems?

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Not all amps are equivalent or made for all loads. On the other hand I don't think it's particularly expensive accomplishing good amp design either, and gets blown out of proportion too.

I can't speak for amp designs in detail, but I think it's easy to build a headphone amp that measures perfect. And still I don't agree on the criticalness of impedance matching. I don't know one single solid-state amp with impedance restrictions. Even if we accept this exceptional case, the call still stands that with solid-state amps you (usually) don't have to care for headphone impedances. And any sonic mismatches are unlikely to be caused by such problems.

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That's rather vague - in terms of a question. The numbers they provide only tell so much. What's the THD of the amp at 16ohms and 650ohms? Are we to assume it's impervious to different loads for no reason?

Not at all. But these HeadRoom specs are in line with other solid-state amps, and since they offer a near-perfect picture, deviations from them towards different load impedances won't destroy it. Not in headphone amps. Even if the THD is increased by a factor of 3 at low impedances (which is a realistic scenario) it is still way below audibility*. As mentioned, I have access to many measuring results, and among solid-state amps they're definitely no evaluation criterion, since frequency responses are linear enough, distortion figures low enough to be inaudible by a large margin – at least *according to established psychoacoustics.

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I'm not implying anything unlike you. I hope Headroom wouldn't sabotage one of their own products to create an artificial tier. Again though, I'm not going to assume one way or the other like you seem to.

Combine your statements («I don't think it's particularly expensive accomplishing good amp design either, and gets blown out of proportion too» ... «all of the amps I've purchased meet the needs of my headphones, so I really can't tell a difference») with the manufacturer specs at hand, and it would be a logical assumption from your part that all HeadRoom desktop amps will most likely sound the same. Yet you're desperately trying to obfuscate this self-evident possibility. I don't have to tell you why.

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You keep saying "I'm sure", but you haven't even touched one. They may be great amps, but headroom doesn't provide enough information for anyone to be sure.

You know, «I'm sure» means: «I'm not 100% sure, but I think...». I get this impression from the multitude of positive reviews. That's where our approaches differ fundamentally: I don't rely on specs (as they tell nothing in the context of headphone amps – see above), but rather on reviews and of course personal audition.

This excursion to amplifiers actually served for demonstrating that cables and electronics can be treated equally when it comes to measuring data (although they still differ by one or two magnitudes): If properly designed and made, they don't show significant* differences. This also applies to the reported blind-test results. In this forum corner you'll find several proponents of the «all amps sound the same» philosophy. You belong to them yourself in my book, despite your reservations.

My point is that if you think all cables sound the same, because the measured differences are too small to be audible, you also have to think that more or less all (solid-state) amps sound the same – for the very same reason. This based on established hearing-threshold figures. (Nick Charles is an expert in this field. Maybe he will help us out with this.)

My point behind the point is that I don't take established hearing-threshold paradigms as seriously as some. There's more to be discovered in audio electronics and psychoacoustics than commonly accepted (or rather: ...whereas many think there's nothing more to be discovered at all). That's why I can live with the «cable-sound mystery».
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[Prog Rock Man]

I have started a thread on the What Hifi series of blind tests, including one on cables here

http://www.head-fi.org/forums/f133/w...esting-486219/

 

[nick_charles]

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Originally Posted by JaZZ /img/forum/go_quote.gif My point is that if you think all cables sound the same, because the measured differences are too small to be audible, you also have to think that more or less all (solid-state) amps sound the same – for the very same reason. This based on established hearing-threshold figures. (Nick Charles is an expert in this field. Maybe he will help us out with this.)

Amps are not quite as straightforward as cables especially when tricky loudpspeaker loads come into play, and impedance mismatches can mean that two ostensibly near identical amps can interact differently under some circumstances.

There are a few DBTS of speaker amps that were positive, David Clark did some way back. The Carver challenge also shows that amps can be audibly different as Bob Carver had to post-fix his amp to null differences to win the challenge.

That said when you put aside exceptional conditions and have two competent (flat FR, low distortion) and near identically specced amps with unproblematic loads driven below clipping differences are harder to find. See "Do all amplifiers sound the same".

As for psychophysics new reserach emerges periodically that refines our knowledge of discimination thresholds, for instance in some carefully controlled circumstances TIM of 0.003% is detectable, but not as distortion only as "different". Other thresholds are remarkably stable. Though more research id always a good idea.

 

[Shike]

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Originally Posted by JaZZ /img/forum/go_quote.gif Yes, I did. But that was just a working hypothesis to have a starting point. You have the opportunity to correct it anytime.

I'd say they're the same if there's nothing dramatically different.

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100% assuming, too.

Then it's not worth delving into.

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No, I don't know this company, but I've heard of the M^3. The Mini^3 apparently is an exception among headphone amps. A budget model, as it seems?

It's a portable amp, and most of them tend to have power limits which would cause issues with loads above 300ohms. Even a few desktop amps have this problem, so it's worth considering.

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I can't speak for amp designs in detail, but I think it's easy to build a headphone amp that measures perfect. And still I don't agree on the criticalness of impedance matching.

The impedance limits, just to make sure we're talking about the same thing, have no relation to impedance matching. If an amp can only support a 300ohm load, it's due to the fact that it can't sufficiently power anything above it without clipping (same for going below the minimum load).

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I don't know one single solid-state amp with impedance restrictions.

Well now you do.

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Even if we accept this exceptional case, the call still stands that with solid-state amps you (usually) don't have to care for headphone impedances. And any sonic mismatches are unlikely to be caused by such problems.

It's one of those "maybe" situations. Most of the time it's probably not an issue, but that still leaves those other times someone will get bit in the butt because they didn't research enough.

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Not at all. But these HeadRoom specs are in line with other solid-state amps, and since they offer a near-perfect picture, deviations from them towards different load impedances won't destroy it.

Proof?

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Not in headphone amps. Even if the THD is increased by a factor of 3 at low impedances (which is a realistic scenario) it is still way below audibility*. As mentioned, I have access to many measuring results, and among solid-state amps they're definitely no evaluation criterion, since frequency responses are linear enough, distortion figures low enough to be inaudible by a large margin – at least *according to established psychoacoustics.

Once again, you're assuming. If the amp clips the distortion can raise dramatically. For example, some digital (speaker) amps can climb to 10% THD based on speaker impedance and output power. So yes, we do need to ask these questions regarding amps regardless of whether they're headphone or speaker - as you simply never know.

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Combine your statements («I don't think it's particularly expensive accomplishing good amp design either, and gets blown out of proportion too» ... «all of the amps I've purchased meet the needs of my headphones, so I really can't tell a difference») with the manufacturer specs at hand, and it would be a logical assumption from your part that all HeadRoom desktop amps will most likely sound the same.

Probably. If I had a set of HD650s and tried them with a portable Headroom amp than no, it probably wouldn't sound the same (almost guaranteed clipping just considering design limitations)

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Yet you're desperately trying to obfuscate this self-evident possibility. I don't have to tell you why.

Actually you do. You've been running the circle jerk here, so what's wrong with you continuing?

Just because something "probably" will work doesn't mean it "will" work. You're just assuming.

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You know, «I'm sure» means: «I'm not 100% sure, but I think...».

And that sums up your entire argument. I'm not going to waste anymore of my patience on it.

 

[JaZZ]

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Originally Posted by Shike /img/forum/go_quote.gif ...The impedance limits, just to make sure we're talking about the same thing, have no relation to impedance matching. If an amp can only support a 300ohm load, it's due to the fact that it can't sufficiently power anything above it without clipping (same for going below the minimum load).

Sorry, I don't have experience with clipping amps (none of the ones I auditioned did), so this is new to me.

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Proof? Once again, you're assuming. If the amp clips the distortion can raise dramatically. For example, some digital (speaker) amps can climb to 10% THD based on speaker impedance and output power. So yes, we do need to ask these questions regarding amps regardless of whether they're headphone or speaker - as you simply never know.

I have every reason to assume that HeadRoom's amps can drive 300-ohm headphones. And I'm astonished about your stubbornness. A majoritiy of HeadRoom's customers use their desktop amps with high-impedance headphones, preferrably HD 650 and 600 and now additionally HD 800. So what's your point? Have you seen reviews of clipping HeadRoom amps?

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Probably. If I had a set of HD650s and tried them with a portable Headroom amp than no, it probably wouldn't sound the same (almost guaranteed clipping just considering design limitations)

You're assuming something? And I disagree: I think as long as you avoid exessive volume levels, the amp with battery drive will sound about the same as with external power supply.

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Actually you do. You've been running the circle jerk here, so what's wrong with you continuing?

I really thought you'd understand what I mean. So I will elaborate. If you think there's a high likelihood of the HeadRoom line-up to sound more or less identical, where's your protest stance against such a fraud and rip-off? I can tell you why you don't dare to say what you think: Too many people would refuse to take you and your conspiracy theory seriously. Am I right?

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And that sums up your entire argument.

I don't think so, and I don't think you really mean what you're saying. It's more like a final kick in the ass.

Your own argumentation is mainly based on special cases: clipping... (actually: what else again?) As mentioned, I didn't and don't experience clipping with the auditioned amps (speakers in the past and now exclusively headphones). And I don't listen at particualrly low levels. Nevertheless, all of them had and have their individual characteristics – not clearly better or worse, just different.

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I'm not going to waste anymore of my patience on it.

Well then, thanks for your previous patience!

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[BIG POPPA]

Some people just like to argue with no motivation to find out for themselves on their own.

 

[JohnFerrier]

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Originally Posted by JaZZ /img/forum/go_quote.gif Have you seen reviews of clipping HeadRoom amps?

Actually, two of the eight HeadRoom amplifiers have clipping indicators and are powered with four AAA batteries. This, of course, means 3 V rails. The clipping indicators "not only tells you when you’ve got a hot signal, it also tells you when your batteries are low." The Airhead and Bithead amps will clip when played loudly enough (performance level rock music and orchestra crescendos).

HeadRoom Total AirHead Owner's Manual

 

[JaZZ]

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Originally Posted by nick_charles /img/forum/go_quote.gif Amps are not quite as straightforward as cables especially when tricky loudspeaker loads come into play, and impedance mismatches can mean that two ostensibly near identical amps can interact differently under some circumstances.

I guess you're speaking of speaker amps. Yes, they're difficult to judge, as they react differently to complex loads with phase shifts as well as to back EMF.
 
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...when you put aside exceptional conditions and have two competent (flat FR, low distortion) and near identically specced amps with unproblematic loads driven below clipping differences are harder to find.

That's for sure. But in sighted tests it's still pretty easy.

 
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As for psychophysics, new reserach emerges periodically that refines our knowledge of discimination thresholds, for instance in some carefully controlled circumstances TIM of 0.003% is detectable, but not as distortion only as "different". Other thresholds are remarkably stable. Though more research id always a good idea.

Good to know that psychoacoustics are not as deadlocked-monolithic and conservative as I thought. 0.003% is remarkably low. I can absolutely reproduce how it's not perceived as such but as an altered characteristic. That's what I expect from (and I think perceive with) harmonic distortion, too, also at such low figures.

The German audio magazine «Stereoplay» has done some research to find a common denominator between their listening tests (according to the chief editor's statements they're done blinded, but I got no details) and their technical tests of amplifiers. And they believe to have found it: The most important thing is a «harmonic» spectrum of harmonic distortions with a continuous, smooth increase with power – clearly more important than low values.

Moreover they believe to have found a further correlation between «good» sound and a low sensitivity to back EMF (in speaker amps). Therefor they have developed a special measuring system including a MLS signal, which reveals parasitic signal alterations in the form of irregular decay phenomena, and this especially with solid-state amps with high negative feedback.

So I think there's really something going on, and maybe one day even cables will find universal rehabilitation: the same test method has revealed cable effects which wouldn't have been noticed with conventional measuring methods.
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[Shike]

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Originally Posted by JaZZ /img/forum/go_quote.gif Sorry, I don't have experience with clipping amps (none of the ones I auditioned did), so this is new to me.

Really? I question whether you actually know what clipping sounds like.

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I have every reason to assume that HeadRoom's amps can drive 300-ohm headphones.

If it's a true 300ohms then I'd have little reason to doubt HeadRoom's portable line even. The problem is some headphones are more inductive than others.

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And I'm astonished about your stubbornness. A majoritiy of HeadRoom's customers use their desktop amps with high-impedance headphones, preferrably HD 650 and 600 and now additionally HD 800. So what's your point? Have you seen reviews of clipping HeadRoom amps?

What about their portables and a HD650 with an impedance curve that can go much higher than 300? Same for the HD800.


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You're assuming something? And I disagree: I think as long as you avoid exessive volume levels, the amp with battery drive will sound about the same as with external power supply.

Portable amps are limited due to design contraints in terms of max voltage and battery life will be sacrificed for increases in current.

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I really thought you'd understand what I mean. So I will elaborate. If you think there's a high likelihood of the HeadRoom line-up to sound more or less identical, where's your protest stance against such a fraud and rip-off?

I never considered them a rip-off, I just prefer to have full measurements? I do consider them a bit overpriced though - but the xfeed circuit may be worth it to some.

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I can tell you why you don't dare to say what you think: Too many people would refuse to take you and your conspiracy theory seriously. Am I right?

HAH, that's the most ridiculous thing I've heard from you yet.

Let's examine something real quick. This is the full impedance graph of the HD650:

If we accept the assertion that most portable amps won't have the voltage to drive 350+ohms (usually limited to 300 at stated - at least while maintaining advertised specs), then we can see that the portable amps (still solid state mind you) wouldn't be suitable.

On the other hand their desktop amps more than likely could with little trouble. This is more based on design principle. Regardless, that's just one example of why full measurements of amps is needed to really speak on them.

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I don't think so, and I don't think you really mean what you're saying. It's more like a final kick in the ass.

You can think all you want, but it's still wrong.

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Your own argumentation is mainly based on special cases: clipping... (actually: what else again?)

Clipping is one of the largest factors, though I'd like to see measurements regarding multiple types of distortion beyond THD. They're also missing specs for things like SNR, which I'm honestly surprised they don't list. I haven't heard anyone complain of hiss though and haven't heard any complaint of it so it's probably safe to (yes, assume) that it's relatively high.

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As mentioned, I didn't and don't experience clipping with the auditioned amps (speakers in the past and now exclusively headphones). And I don't listen at particualrly low levels. Nevertheless, all of them had and have their individual characteristics – not clearly better or worse, just different.

Maybe you just don't know what clipping sounds like?

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Well then, thanks for your previous patience!

Hopefully this final post ends the matter. It's not a conspiracy or anything of the sort, I don't believe in such things. I just won't speak on the capability of an amp without having numbers to back it up.


Next you're going to tell me a cmoy could drive AKG K1000's with no distortion

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Originally Posted by JohnFerrier Actually, two of the eight HeadRoom amplifiers have clipping indicators and are powered with four AAA batteries. This, of course, means 3 V rails. The clipping indicators "not only tells you when you’ve got a hot signal, it also tells you when your batteries are low." The Airhead and Bithead amps will clip when played loudly enough (performance level rock music and orchestra crescendos). HeadRoom Total AirHead Owner's Manual

That helps a lot, thank you for informing us on this fact.

I'm glad they have a form of indication though - something many amps just don't have.