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WolfX700 Measurement of Topping A90 Headphone Amp

imrul

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Can the A90 or the new topping pre-amp be used as the input to an energizer for electrostatic headphones?
 

Veri

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Can the A90 or the new topping pre-amp be used as the input to an energizer for electrostatic headphones?
Sure why not. As long as you don't exceed the maximum input level on the energizer.
 

imrul

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Sure why not. As long as you don't exceed the maximum input level on the energizer.

The reason I ask is that I've read that if you're going to use an energizer to power electrostats, you have to feed it with a power amp. So that made me think that regular headphone amps or preamps weren't powerful enough for energizers.
 

JohnYang1997

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The reason I ask is that I've read that if you're going to use an energizer to power electrostats, you have to feed it with a power amp. So that made me think that regular headphone amps or preamps weren't powerful enough for energizers.
Ok well, as you stated, you need a power amp.
 

Tks

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I think the explanation is much simpler. In the 1980’s and 1990’s, audiophool rags like The Absolute Sound and Stereophile would rail against opamps because of an uninformed, unscientific belief that they must sound worse than discrete solid state or tube circuits because they were (supposedly) less expensive to implement.. Similarly, they nonsensically railed against the use of JFET and MOSFET transistors (using such make-believe terminology as hearing a “MOSFET mist” to the sound), preferring circuits using bipolar transistors. Finally, they insisted on solid state equipment using toroidal transformers and tube using E-I core transformers instead of other less impressive looking but in actuality better performing transformers such as split bobbin, R-core, or C-core (dependent on what the application warranted). Generally, they took the position that the older or more esoteric the technology, the better the sound. That’s why in large measure they preferred turntables to CD players and tubes to solid state. It was all quite silly and undoubtedly based on advertising dollars. They duped a lot of their readers into this type of thinking, and several of the biases they introduced, including their anti-opamp positions, survive to this day, 20-30 years later.

You give me more credit than my noob-ass to audio deserves. I was more along the lines addressing the modern day DIY and people with some electrical literacy and basic understandings. The people you allude to are bygone era fossils that are a generation away from being put into the ground along with their laughable nonsense. MOSFET mist lmao... Reminds of the modern day ESS glare term. That made my laugh a bit.

But to the topic.. You say they preferred esoteric/bespoke designs. Well sure, there's nothing really wrong with that from a artistic approach. But as I alluded to earlier(in contrast to mechanical watch making, or car production), it's hard to make electrical engineering sexy seeing as how PCB's are usually hidden away and such. But these people are insane to think some boutique no-name company could ever outperform the skills of doctors of electrical engineering involved in multi-billion dollar R&D projects if their teams were granted free reign on designing a top their product not destined for the mainstream market. So unless those morons who believe these boutique companies can out-do something like an instance of AP's design team asked to go wild making a cost-is-no-object performance DAC/ADC or AMP for instance... I don't even see the logic of even holding this belief EVEN IF all the advertising in the world was piled on to me in the modern day. It was okay to be blind in the advent of digital... To hold such beliefs today to me seems tantamount of thinking the Earth is flat, or the solar system's model is geocentric.

It just doesn't make sense even if you're a complete noob like me by simply looking at the fact that hyper-price sensitive multinational research departments are blowing through money like no tomorrow, are somehow going to be producing products destined for millions, and oversight/reliability expectations of a global market - and have those products somehow be inferior to some esoteric nonsense from boutique companies hiding in bushes from audio analyzers, praying no one sends in one of there devices for independent evaluation most of the time.

I don't know - I'm relatively young and just can't fathom a reason beyond ignorance, or psychosis that would lead grown adults, with life experiences doing transactions with money in their lives, to somehow hold these wildly incomprehensible beliefs. Like they won't even air on the side of caution, they go all in as if fighting as activists for their cases sometimes...
 

YSC

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You give me more credit than my noob-ass to audio deserves. I was more along the lines addressing the modern day DIY and people with some electrical literacy and basic understandings. The people you allude to are bygone era fossils that are a generation away from being put into the ground along with their laughable nonsense. MOSFET mist lmao... Reminds of the modern day ESS glare term. That made my laugh a bit.

But to the topic.. You say they preferred esoteric/bespoke designs. Well sure, there's nothing really wrong with that from a artistic approach. But as I alluded to earlier(in contrast to mechanical watch making, or car production), it's hard to make electrical engineering sexy seeing as how PCB's are usually hidden away and such. But these people are insane to think some boutique no-name company could ever outperform the skills of doctors of electrical engineering involved in multi-billion dollar R&D projects if their teams were granted free reign on designing a top their product not destined for the mainstream market. So unless those morons who believe these boutique companies can out-do something like an instance of AP's design team asked to go wild making a cost-is-no-object performance DAC/ADC or AMP for instance... I don't even see the logic of even holding this belief EVEN IF all the advertising in the world was piled on to me in the modern day. It was okay to be blind in the advent of digital... To hold such beliefs today to me seems tantamount of thinking the Earth is flat, or the solar system's model is geocentric.

It just doesn't make sense even if you're a complete noob like me by simply looking at the fact that hyper-price sensitive multinational research departments are blowing through money like no tomorrow, are somehow going to be producing products destined for millions, and oversight/reliability expectations of a global market - and have those products somehow be inferior to some esoteric nonsense from boutique companies hiding in bushes from audio analyzers, praying no one sends in one of there devices for independent evaluation most of the time.

I don't know - I'm relatively young and just can't fathom a reason beyond ignorance, or psychosis that would lead grown adults, with life experiences doing transactions with money in their lives, to somehow hold these wildly incomprehensible beliefs. Like they won't even air on the side of caution, they go all in as if fighting as activists for their cases sometimes...
I believe that anti opamp thing hold some truth in cases like high output power need that most opamp just isn't capable of a few years ago, and headphones like the HE-6 are out and back then. but now tech advances and seeing the A90 and THX amps it seems like that advantage of discrete have been going away also
 

Tks

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I believe that anti opamp thing hold some truth in cases like high output power need that most opamp just isn't capable of a few years ago, and headphones like the HE-6 are out and back then. but now tech advances and seeing the A90 and THX amps it seems like that advantage of discrete have been going away also

I mean people involved in hardware modifications. Those are primarily the people I would assume are the MOST up to date on the latest technological developments. Also, I really should get the HE-6... I am dying to find out what are these supposed headphones are THAT demanding, that somehow amps are starved for power to drive them. I got HD6XX's 58X's and LCD2C's... I am sitting currently at the lowest reference level on my RME (-5) at -3.5db, with lowest gain on my 789... I cannot breach 12 o'clock at all unless I am listening to a VERY select few albums.

I have never understood this power facination people have with headphone amps. Every single one I've tried... feels like it can blow my ears to pieces..
 
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JohnYang1997

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I believe that anti opamp thing hold some truth in cases like high output power need that most opamp just isn't capable of a few years ago, and headphones like the HE-6 are out and back then. but now tech advances and seeing the A90 and THX amps it seems like that advantage of discrete have been going away also
Well. A90 in fact can be designed with the very same way in 2009. There's nothing that's changed from the purely component perspective.
Even in higher power domain, lm3886 can be used in parallel, in bridge configuration which can result in 300W+ monster if design correctly.
There are people that can take advantage of some aspects of discrete with sacrifice of simplicity and perhaps reliability. In some cases it can be better using discrete components.
 

JohnYang1997

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Right but what's the reason for that? Is it merely an issue of power deliver or something else?
That really depends on what energizer you have. Some(in fact majority) are actually line input and drive the headphone in itself. Some may use a transformer to boost up voltage. In the end, I don't recommend to use any product outside the use condition it's designed for.
 

maverickronin

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Right but what's the reason for that? Is it merely an issue of power deliver or something else?

Which kind are you talking about? A step up transformer box like the Stax SRD-7 or Woo WEE or an actual amplifier? (Anything from the Stax 252S to the Blue Hawaii)

Sometime people apply the word "energizer" to both kinds just because 'stats have completely different requirements than normal headphone.

The transformer boxes need input from a power amp. They might step of the voltage 20 or 30 times and they need some current capacity to get that done. You probably shouldn't use the output from a high power headamp either. Most wouldn't like putting out full power into an 8 ohm (or less) load which is what most of the step up transformers are likely to be.

You could use something like the A90 as a preamp for a full electrostatic amp if you had a problem with the pot on the amp.
 

YSC

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Well. A90 in fact can be designed with the very same way in 2009. There's nothing that's changed from the purely component perspective.
Even in higher power domain, lm3886 can be used in parallel, in bridge configuration which can result in 300W+ monster if design correctly.
There are people that can take advantage of some aspects of discrete with sacrifice of simplicity and perhaps reliability. In some cases it can be better using discrete components.
Right, I am personally technically noob here but I am not sure about things like slew rate etc. In the amp design segment. For the power requirements of big plan are like he6 I have read that the manufacturer Hifiman have said something like in low notes they benefit from more W of power to control the diaphragm, but no idea why that’s the case, maybe high magnetic flux of the planar and the large driver diaphragm? Really plan guessing but the thx 789 according to the measurements here should be able to deliver what even the he6 needed, the power crave is more when most headlamps only able to deliver mW range of power and while some like the auralic Taurus, Bryston BHA-1, headamp GS-X etc. Achieve the power with discrete, be it marketing or actual design need
 

Veri

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most headlamps only able to deliver mW range of power and while some like the auralic Taurus, Bryston BHA-1, headamp GS-X etc. Achieve the power with discrete, be it marketing or actual design need
headlamps able to drive christmas lightning? :p
 
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JohnYang1997

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Right, I am personally technically noob here but I am not sure about things like slew rate etc. In the amp design segment. For the power requirements of big plan are like he6 I have read that the manufacturer Hifiman have said something like in low notes they benefit from more W of power to control the diaphragm, but no idea why that’s the case, maybe high magnetic flux of the planar and the large driver diaphragm? Really plan guessing but the thx 789 according to the measurements here should be able to deliver what even the he6 needed, the power crave is more when most headlamps only able to deliver mW range of power and while some like the auralic Taurus, Bryston BHA-1, headamp GS-X etc. Achieve the power with discrete, be it marketing or actual design need
It's really a complex situation.

It's probably due to that there weren't people wanting to design best measuring amps while able to do so.

The old school guys like Violectric were really good years ago and is pretty consistent in performance. But that's still less than 110dB of performance.
Pretty much the same thing applies to SPL as well. They both use discrete circuit in some area.

Another reason is that there weren't great DACs to pair with performance of the amp we and THX make. Hence there's simply no need for such performance.

Also a big helping point is the existence of APx555. It's easy to use and let us to see harmonics down to -150dB. Highly automatic process save us lots of time and energy while doing development. The tools weren't that good at the time and rarely people can afford it. I used pre-distortion to calibrate my measuring rig in order to measure down to -130dB it's really frustrating.

Also people who has the ability to do such design may not want to design audio products to begin with. So I am surprised in some way that it took so long for THX to make those designs and even then the noise performance is simply not great. There should have been people making such design in early 2010s. O2 could have been as good as Atom or even better.

Tom from neurochrome made some designs pretty early in 2014 and 2016 but rarely people talk about it. Majority of people don't even pursue high performance audio.They want some coloration. It is only brought up after THX hit the market. Same thing as Harman Target curve, where Etymotic has done it 30 years ago but rarely people talk about it. Only after Harman does it, companies started to follow. And the target doesn't even sound that great especially the IE targets.

So to sum it up a bit. The need for it, the people who are able to do it and the tools needed to do it are all essential for a wave.
 

YSC

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It's really a complex situation.

It's probably due to that there weren't people wanting to design best measuring amps while able to do so.

The old school guys like Violectric were really good years ago and is pretty consistent in performance. But that's still less than 110dB of performance.
Pretty much the same thing applies to SPL as well. They both use discrete circuit in some area.

Another reason is that there weren't great DACs to pair with performance of the amp we and THX make. Hence there's simply no need for such performance.

Also a big helping point is the existence of APx555. It's easy to use and let us to see harmonics down to -150dB. Highly automatic process save us lots of time and energy while doing development. The tools weren't that good at the time and rarely people can afford it. I used pre-distortion to calibrate my measuring rig in order to measure down to -130dB it's really frustrating.

Also people who has the ability to do such design may not want to design audio products to begin with. So I am surprised in some way that it took so long for THX to make those designs and even then the noise performance is simply not great. There should have been people making such design in early 2010s. O2 could have been as good as Atom or even better.

Tom from neurochrome made some designs pretty early in 2014 and 2016 but rarely people talk about it. Majority of people don't even pursue high performance audio.They want some coloration. It is only brought up after THX hit the market. Same thing as Harman Target curve, where Etymotic has done it 30 years ago but rarely people talk about it. Only after Harman does it, companies started to follow. And the target doesn't even sound that great especially the IE targets.

So to sum it up a bit. The need for it, the people who are able to do it and the tools needed to do it are all essential for a wave.
Right, for the part of colouration personally I think that’s what this hobby is about, especially all headphones have it own signature so the crossfeed/talk, high frequency roll off and things like potentiometer or stepped attenuators are stuffs ppl willing to pay extra (and a lot) for. And for transparency tbh from my own experience anything measures with SINAD >80 already is very difficult if not impossible to detect while listening, but if saying underpowered amp for said phone will be much more obvious
 

JohnYang1997

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Found something weird. I didn't care much about SNR at maximum output. Just looking around the forum and saw 133dB SNR from benchmark hpa4. The noise is 2uV, the full range output is 11V. But what A90 has is much less than 2uV noise and full range of 19V balanced how come it's worse. Assuming A90 has 2uV noise, with that output voltage I should be getting 139dB SNR. hmmmm
 

YSC

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Found something weird. I didn't care much about SNR at maximum output. Just looking around the forum and saw 133dB SNR from benchmark hpa4. The noise is 2uV, the full range output is 11V. But what A90 has is much less than 2uV noise and full range of 19V balanced how come it's worse. Assuming A90 has 2uV noise, with that output voltage I should be getting 139dB SNR. hmmmm
I think it maybe the measurement gear problem? I think wolfx have demo that the base noise of his apx is around 120db?
 

JohnYang1997

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Just did the measurements.
136dB of SNR for BA in BA out
141dB of SNR for SE in BA out
The residue noise with BA in when maxed out volume isn't particularly low that is 2.6uV. When turn the volume to null, it reduces to 1uV for BA out.
 
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