[chesebert]

amp input is a much much easier load to drive than any headphone. Driving 50K load with constant imp and phase is not the same as driving a nominal load of 33ohm with variable imp and phase over the audio band. 

 

[chesebert]

@chesebert, if bass from Hugo's RCA out is very good , it will be very good too from headphone out because there is no difference between RCA and headphone out as both are same and share the same output from the circuit of hugo.

No. They are not driving the same load. Try with a good amp (e.g., pass labs or Headamp are both good choices as are all the other Gilmore and AMB lab designs) and report back. 

 

[JaZZ]

  amp input is a much much easier load to drive than any headphone. Driving 50K load with constant imp and phase is not the same as driving a nominal load of 33ohm with variable imp and phase over the audio band. 

 
That's certainly true to an extent, but highly overrated. I have experimented with DAC line-outs in the past, using them for driving headphones directly. As long as the output impedance is sufficiently low for a decent damping factor, both my then Theta Pro basic 2 (6 Ω) and my Bel Canto DAC2 (15 Ω) could drive the HD 650 with ease and to ear-bleeding volume levels – and sounded faster and cleaner than any amp. I used the configuration as a reference for testing the sonic characteristics of different headphone amps. It was a fascinating and enlightening experience that's left traces in my audio philosophy. One major insight is that the notion of «good» or «beautiful» or «spectacular sound» has little to do with high fidelity. Now with the Hugo or DAVE it's even easier to get to know how the (attached) headphone amps really sound. A common trait is that they make the sound richer. The original signal sounds relatively empty in comparison, bordering on dryness in some cases. From Rob Watts' posts on this forum I've learnt that it's in fact the added harmonic distortion that's responsible for the phenomenon. It's astonishing how his technical excellence is consequentially underrated, in turn the own subjective perception and its personal interpretation is massively overrated.
 
It's revealing that none of the die-hard amp advocates has ever seriously tried the alternative I've repeatedly proposed: compensating for the logically imperfect tonal balance of the own reproduction system in the form of equalizing instead of the crude component synergy approach relying on euphonic masking effects.

 

[chesebert]

Did Hugo ever publish the imp and watt (rms) chart? Do we know the rise time for Hugo driving HD650 or another headphone? 
 
Having been in this hobby for almost two decades, I have tried almost everything there is to try (including direct DAC drive) and I am at a point where I just want to have good sound - I really don't care about technical perfection anymore. For example, I like my Harbeth not because it's technical brilliant (with vibrating panel and all that), but because it sounds good to me. Same goes for Linn gear.
 
If you chase perfection, you journey will never end.

 

[phonomat]

   
That's certainly true to an extent, but highly overrated. I have experimented with DAC line-outs in the past, using them for driving headphones directly. As long as the output impedance is sufficiently low for a decent damping factor, both my then Theta Pro basic 2 (6 Ω) and my Bel Canto DAC2 (15 Ω) could drive the HD 650 with ease and to ear-bleeding volume levels – and sounded faster and cleaner than any amp. I used the configuration as a reference for testing the sonic characteristics of different headphone amps. It was a fascinating and enlightening experience that's left traces in my audio philosophy. One major insight is that the notion of «good» or «beautiful» or «spectacular sound» has little to do with high fidelity. 
Exactly. You've got your answer right there. Btw, these are actually adjectives that are positively connotated. Can you give me a good reason why, given the choice, I, or anyone else for that matter, should not prefer "good" or "beautiful" sound to whatever you term "high fidelity"? (Fidelity to what exactly? Every piece of music is being "colored" at the point of its recording. There is no way around it. The ideal you seem to be evoking exists in theory only.)
Now with the Hugo or DAVE it's even easier to get to know how the (attached) headphone amps really sound. A common trait is that they make the sound richer.
Exactly. Many people would consider this a good thing.
The original signal sounds relatively empty in comparison, bordering on dryness in some cases. From Rob Watts' posts on this forum I've learnt that it's in fact the added harmonic distortion that's responsible for the phenomenon.
That is just a matter of nomenclatura. Is it really important what you call it? The interesting part is how it is perceived by the listener. If it has a agreeable effect, then it's all good.
It's astonishing how his technical excellence is consequentially underrated, in turn the own subjective perception and its personal interpretation is massively overrated.
This point is the most baffling to me. How on earth could you overrate subjective perception? It is literally all that counts in this hobby!
 
 
From the posting guidelines of this forum:
 

'Having doubts about something you see in a design is fair enough, but to quote Robert Pirsig: "

The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility, it's right. If it disturbs you it's wrong until either the machine or your mind is changed."

 It is quite possible to derive satisfaction from listening with any audio gear as much from your appreciation of the design (whether how it looks or how it measures) as much as how it reproduces music. No method of appreciation is "wrong".'
 
It's revealing that none of the die-hard amp advocates has ever seriously tried the alternative I've repeatedly proposed: compensating for the logically imperfect tonal balance of the own reproduction system in the form of equalizing instead of the crude component synergy approach relying on euphonic masking effects.
 
That might or might not have something to do with the fact that, frankly, equalizing is a huge PITA. 

 

[JaZZ]

Spoiler: Warning: Spoiler!

 

  That's certainly true to an extent, but highly overrated. I have experimented with DAC line-outs in the past, using them for driving headphones directly. As long as the output impedance is sufficiently low for a decent damping factor, both my then Theta Pro basic 2 (6 Ω) and my Bel Canto DAC2 (15 Ω) could drive the HD 650 with ease and to ear-bleeding volume levels – and sounded faster and cleaner than any amp. I used the configuration as a reference for testing the sonic characteristics of different headphone amps. It was a fascinating and enlightening experience that's left traces in my audio philosophy. One major insight is that the notion of «good» or «beautiful» or «spectacular sound» has little to do with high fidelity. 
Exactly. You've got your answer right there. Btw, these are actually adjectives that are positively connotated. Can you give me a good reason why, given the choice, I, or anyone else for that matter, should not prefer "good" or "beautiful" sound to whatever you term "high fidelity"? (Fidelity to what exactly? Every piece of music is being "colored" at the point of its recording. There is no way around it. The ideal you seem to be evoking exists in theory only.)
Now with the Hugo or DAVE it's even easier to get to know how the (attached) headphone amps really sound. A common trait is that they make the sound richer.
Exactly. Many people would consider this a good thing.
The original signal sounds relatively empty in comparison, bordering on dryness in some cases. From Rob Watts' posts on this forum I've learnt that it's in fact the added harmonic distortion that's responsible for the phenomenon.
That is just a matter of nomenclatura. Is it really important what you call it? The interesting part is how it is perceived by the listener. If it has a agreeable effect, then it's all good.
It's astonishing how his technical excellence is consequentially underrated, in turn the own subjective perception and its personal interpretation is massively overrated.
This point is the most baffling to me. How on earth could you overrate subjective perception? It is literally all that counts in this hobby!
 
It's revealing that none of the die-hard amp advocates has ever seriously tried the alternative I've repeatedly proposed: compensating for the logically imperfect tonal balance of the own reproduction system in the form of equalizing instead of the crude component synergy approach relying on euphonic masking effects.
 
That might or might not have something to do with the fact that, frankly, equalizing is a huge PITA. 

 
Hi Phonomat
 
I'm glad that you offer me the opportunity to respond to the questions my arguments have raised.
 

One major insight is that the notion of «good» or «beautiful» or «spectacular sound» has little to do with high fidelity. 
Exactly. You've got your answer right there. Btw, these are actually adjectives that are positively connotated. Can you give me a good reason why, given the choice, I, or anyone else for that matter, should not prefer "good" or "beautiful" sound to whatever you term "high fidelity"? (Fidelity to what exactly? Every piece of music is being "colored" at the point of its recording. There is no way around it. The ideal you seem to be evoking exists in theory only.)
Now with the Hugo or DAVE it's even easier to get to know how the (attached) headphone amps really sound. A common trait is that they make the sound richer.
Exactly. Many people would consider this a good thing.

 
I don't mean to prescribe any specific sonic ideals to others. But the common approach to use amplifiers for tayloring the sound comes with a serious downside: reduced transparency, reduced fidelity. And despite this reproducible mechanism it is considered a golden standard by many. That's my ongoing motivation to offer an alternative approach promising even higher sensual delight: ultimate purity combined with euphony and spectacularity if the recordings call for – or if the listener wants it. It's unfortunate that this main intention behind my proposals gets constantly ignored.
 

The original signal sounds relatively empty in comparison, bordering on dryness in some cases. From Rob Watts' posts on this forum I've learnt that it's in fact the added harmonic distortion that's responsible for the phenomenon.
That is just a matter of nomenclatura. Is it really important what you call it? The interesting part is how it is perceived by the listener. If it has a agreeable effect, then it's all good.
It's astonishing how his technical excellence is consequentially underrated, in turn the own subjective perception and its personal interpretation is massively overrated.
This point is the most baffling to me. How on earth could you overrate subjective perception? It is literally all that counts in this hobby!

 
Yes, certainly! Therefore my constant attempt to convince people for trying the alternative approach. But I'm certainly criticizing statements that proclaim the truth solely on the basis of subjective perception like the above. From own experience I fully agree with Rob Watts. Not least because I do have insight in both approaches, whereas the experience of people claiming reamplification be the Holy Grail is usually limited to the latter approach.
 

It's revealing that none of the die-hard amp advocates has ever seriously tried the alternative I've repeatedly proposed: compensating for the logically imperfect tonal balance of the own reproduction system in the form of equalizing instead of the crude component synergy approach relying on euphonic masking effects.
That might or might not have something to do with the fact that, frankly, equalizing is a huge PITA. 

 
I read a lot of posts claiming «I don't equalize». No further explanation. It's not even questioned on this forum, because it's considered a valid approach. I'm aware that equalizing is not for everyone, and I'm fully aware that for some or many coloring the signal via amps to make it more euphonic may be the better, more convenient way to listening pleasure. But it should be noted that all the excuses around this approach including the proclamation of full-fledged desktop amps as afterburners being necessary for Chord DAC/amp combos aren't oriented on reality, but on convenience and lack of flexibility. I understand that it's also an effect of a consumer mentality established on Head-Fi. An important part of the hobby is buying gear.
 
There's a useful tool called SonarWorks consisting of preproduced EQ curves for many buyable headphones. I don't know it from own experience, but it looks very good from what I gather and does the job for those who don't want to experiment themselves with equalizers – for a fraction of the price of high-end amps. It's a much more powerful tool and «effect device» than any amp, and you can taylor the curves to your preferences. Maybe I would use it myself, but none of my headphones is standard – two are partly homegrown and two are modified. However, for me equalizing is fun, maybe just as fun as buying gear is for others. And you can learn a lot (by the inevitable constant errors) on an admittedly long and hard way to perfection.

 

[Here2rock]

On Hugo: 100 ohm load, 127.18 milliwatts is the maximum power. On TT: 31 ohm load, 336.26 milliwatts. For both units that's the maximum power observed.

Thank you that makes sense, newbie question, ideally should you be looking to pair the TT with 31 Ohm load HP? If you look at just the numbers 336.26 miliwatts is not earth shattering, yet listeners say it is more than loud enough.
 
Are these specifications official? If they are then they maybe very conservative numbers on the safe side. 
 
Looking at these numbers:
 
Ohm mW
16 15,87
25 20,51
31 41,48
62 80,84
100 127,18
199 101,49
300 67,28
763 26,48
 
Why there is more output with higher harder to drive HPs? It does not make sense to me.

 

[chesebert]

As suspected, Hugo is severely current limited.

 

[headwhacker]

  Thank you that makes sense, newbie question, ideally should you be looking to pair the TT with 31 Ohm load HP? If you look at just the numbers 336.26 miliwatts is not earth shattering, yet listeners say it is more than loud enough.
 
Are these specifications official? If they are then they maybe very conservative numbers on the safe side. 
 
Looking at these numbers:
 
Ohm mW
16 15,87
25 20,51
31 41,48
62 80,84
100 127,18
199 101,49
300 67,28
763 26,48
 
Why there is more output with higher harder to drive HPs? It does not make sense to me.

Where did you get these numbers?

 

[reeltime]

Would you consider an AK120 II a better player solution for the Hugo compared to MacBook Pro running Audirvana+?

Same connection in both cases (optical, to avoid RFnoise) and obviously same HiRes source files.

I use the USB connection.  You can't pass native DSD over the optical connection.  

 

[rkt31]

@chesebert, hugo is current limited ? can't believe this statement. did you even check the output impedance of hugo ? did you come across any other dac with such low output impedance ? if it was current limited , what was the purpose of such low output impedance ? I am not an expert but I have driven 8ohm single driver speakers directly from mojo and hugo to more than enough listening levels ( I barely needed to go beyond dark blue ) and never did I feel sound was restrained. can you drive 8ohm speakers directly from any other dac ? in fact current and low output impedance is the forte of these chord dacs . I drive my benchmark ahb2 power amp directly from hugo and share same RCA out to amp and powered sub by RCA splitter and believe me there is no degradation of sound by sharing same RCA to two devices. many have reported that adding two headphones simultaneously to hugo causes very little sound degradation/attenuation. how is that possible if hugo is current limited ? in fact once I attached my fiio x3 2k headphone out to my benchmark power amp and the sound became slow and devoid of any punch which is the indication of not enough current ability/ high output impedance. only one word for these chord dacs , transparency to transport you to the venue. I don't care about bass , warmth, sweetness as long as I feel the singers/performers in front of me courtesy mojo and hugo ( dave is out of reach of me but I am happy with these two little magical devices )

 

[Mojo ideas]

Actually John, you just made me want to purchase some Lego for my son (who happens to be 18)! :veryevil:

Well I hope to see a good an accurate representation of the two waveforms better get some big douplo ones too though for the typical Dac though. ‍

 

[Mojo ideas]

Thank you that makes sense, newbie question, ideally should you be looking to pair the TT with 31 Ohm load HP? If you look at just the numbers 336.26 miliwatts is not earth shattering, yet listeners say it is more than loud enough.

Are these specifications official? If they are then they maybe very conservative numbers on the safe side. 

Looking at these numbers:

Ohm mW
16 15,87
25 20,51
31 41,48
62 80,84
100 127,18
199 101,49
300 67,28
763 26,48

Why there is more output with higher harder to drive HPs? It does not make sense to me.

I may have missed something but has anyone yet stated just how these sets figures were obtained are these impulse tests.

 

[Jawed]

On Hugo: 100 ohm load, 127.18 milliwatts is the maximum power. On TT: 31 ohm load, 336.26 milliwatts. For both units that's the maximum power observed.

Thank you that makes sense, newbie question, ideally should you be looking to pair the TT with 31 Ohm load HP?

No.

The power of an amplifier basically tells you how loudly it will play, if you have hard to drive headphones. Headphones with low impedance need more current than headphones with higher impedance. BUT the sensitivity of the headphones is an important number.

For example lots of IEMs have very low impedance, but they are also very sensitive. That means the voltage can be low. So IEMs normally sound loud with a much lower volume setting than full sized headphones.

So the low impedance of IEMs doesn't matter very much.

There are full size headphones that are low in impedance and also low in sensitivity. So you have to turn the volume control much higher. And because they have low impedance, that requires the amplifier to deliver more power. There are two simple formulae:

power = volts x amps

volts = impedance x amps

So a bit of algebra gives you this formula:

power = impedance x amps x amps

or:

power = volts x volts / impedance.

So if we use the second formula we know that 300 ohm headphones can be driven at 4.49V by Hugo:

4.49 x 4.49 = 20.1601

Divide that by 300 ohms:

= 0.0672 watts.

Which is the same as 67.2 milliwatts (thousandths of a watt). Which is very close to the number that is reported: 67.28 milliwatts.

If the amplifier can't deliver the power it will crackle and make other horrible noises.

In the end you have to know the sensitivity specification for a headphone and the impedance, to get an idea of how hard it is to drive. If the sensitivity is really really low then something like Hugo won't have enough volts. In that case Hugo isn't running out of power, instead the volume control just doesn't go far enough! It will also sound crackly though when you reach the maximum loudness.

Are these specifications official? If they are then they maybe very conservative numbers on the safe side. 

No these numbers are from a site that did some testing.

Looking at these numbers:

Ohm mW
16 15,87
25 20,51
31 41,48
62 80,84
100 127,18
199 101,49
300 67,28
763 26,48

Why there is more output with higher harder to drive HPs? It does not make sense to me.

If we use the formula above you can see that at 199 ohms:

power = volts x volts / impedance
0.10131 = 4.49 x 4.49 / 199

everything is fine (the measured number is 0.10149 watts). With lower impedance at the same voltage, more power is required, 101 milliwatts at 199 ohms compared with 67 milliwatts at 300 ohms.

That's the same as saying "a lower impedance headphone needs more power at the same volume control position."

Less impedance is like a fat water pipe. More impedance is like a narrow water pipe. The amount of water that can flow through the pipe depends on how fat the pipe is. So if the water pressure is the same, more water flows through the pipe that impedes less. The pipe on your toilet where all the **** goes is FAT. It needs to be fat because lots of water wants to travel through it very quickly in 3 or 4 seconds (and you might have done a fat ****!). But the pipe that puts water into the tank is much thinner, because it's OK to fill the tank slowly in a minute or two. So the fat pipe has low impedance and the thin pipe has high impedance.

Back to the measurements for Hugo, when you look at 100 ohms you see something has gone wrong:

0.201601 = 4.49 x 4.49 / 100

but the measured power is only 0.12718 watts - quite a lot of power is missing: 0.201601 - 0.12718 = 0.074421. That's about 74 milliwatts that's gone missing. That's because Hugo isn't very powerful. And the numbers get worse as the impedance falls lower.

The lack of power only matters if the headphone needs lots of volts (water pressure). If the headphone is an IEM, which doesn't need lots of volts, then the formula is fine. For example, Shure SE 535:

http://reference-audio-analyzer.pro/en/report/hp/shure-se-535.php

has 26 ohms impedance. In the table for Hugo at 25 ohms there's 20.51 milliwatts of power available. According to that page, for 94dB SPL (that's quite loud) you need 4 milliwatts of power. So Hugo has plenty of power. You can turn it up even louder as there's more voltage range left and more power available.

Eventually you'll get crackling distortion from Hugo if you keep on increasing the volume. But you might kill the IEMs by playing them too loudly first.

 

[Jawed]

I may have missed something but has anyone yet stated just how these sets figures were obtained are these impulse tests.

I don't think they are impulse tests, I believe they are continuous tests. They are from a Russian language test site, so it's hard to fully understand their testing. I wrote about these tests here:

http://www.head-fi.org/t/702787/chord-hugo/14235#post_13060495