Bottlehead Crack Headphone Amplifier Kit Review

[generic]

Are you confusing the purpose of guitar vs headphone/speaker amps?

Guitar amps are considered as part of the instrument chain. Musicians use their understanding of the amps (including exploiting characteristics of tubes) to create interesting sounding distortions, on top of their original function as sound amplifiers. The resultant sound is recorded.

Never mix up the producing of a sound with reproducing this sound.

This is completely missing the point. I fully understand both the guitar signal chain and the playback signal chain. The point is that having a tube in either chain results in a different tone and quality of sound. The differences are obvious with side-by-side comparisons.

Electric guitars generate very low volume sounds by having strings vibrate over magnets -- this is either sent through a clean amplifier or a distorted amplifier. The amplifier can use tubes or not. Tubes produce a different, smoother tone and at a predictably louder perceived volume.

Audiophile music sources are sent through either tube or non-tube amplifiers, but generally clean amplifiers (excepting Audio GD and a few others). The fringe characteristics (i.e., marginal distortion) with playback is predictably different between tube and non-tube amps.

The bottom line: Tubes produce similar overtones and second or third order effects with both guitar amps and playback amps. This can be easily demonstrated. Tubes test poorly but have an integrated coherence to their distortion -- in my experience this is lost in the conventional audio charts (at ASR) and the quick rejections by some of "bad, bad tubes." Yes, tubes objectively suck. I don't dispute that and don't personally like them for many uses, but I want the SCIENCE to be complete as to why. I want to know what makes for "desirable" tube output versus muddy and "undesirable" tube output. To this end, I'm seeking more advanced measurements of 2nd and 3rd order effects, and presentations of those measurements.

 

[generic]

Comparison with guitar amps is interesting but limited. Guitar amps are designed from the outset to distort. Designers actually deliberately misuse design elements in a way that is calculated to deliver gross distortion.

Yes, I have experience with both types of amps. Guitar + solid state = often clean, dry, and brittle. Audiophile + solid state = often clean, dry, and brittle. Guitar + tube = smooth complex distortions and the ability to distort. Audiophile + tube = smooth complex distortions and often a perceived experience that is 'better than the numbers suggest.' [Per the panther vs. data in this Crack review.]

For any and all cases I want to see effective charts as to why tube amp distortion (e.g., the grass in the sawtooth charts) is routinely preferred over the grass or other factors with solid state products. I'm merely seeking charts to show meaningful differences. While I routinely check ASR reviews as a useful data point, the tube-related charts leave me wanting more. There are indeed pleasing tube amps and unpleasant tube amps. What makes them different?

 

[tomtoo]

This is completely missing the point. I fully understand both the guitar signal chain and the playback signal chain. The point is that having a tube in either chain results in a different tone and quality of sound. The differences are obvious with side-by-side comparisons.

Electric guitars generate very low volume sounds by having strings vibrate over magnets -- this is either sent through a clean amplifier or a distorted amplifier. The amplifier can use tubes or not. Tubes produce a different, smoother tone and at a predictably louder perceived volume.

Audiophile music sources are sent through either tube or non-tube amplifiers, but generally clean amplifiers (excepting Audio GD and a few others). The fringe characteristics (i.e., marginal distortion) with playback is predictably different between tube and non-tube amps.

The bottom line: Tubes produce similar overtones and second or third order effects with both guitar amps and playback amps. This can be easily demonstrated. Tubes test poorly but have an integrated coherence to their distortion -- in my experience this is lost in the conventional audio charts (at ASR) and the quick rejections by some of "bad, bad tubes." Yes, tubes objectively suck. I don't dispute that and don't personally like them for many uses, but I want the SCIENCE to be complete as to why. I want to know what makes for "desirable" tube output versus muddy and "undesirable" tube output. To this end, I'm seeking more advanced measurements of 2nd and 3rd order effects, and presentations of those measurements.

Missinterpretation? It's easy just never talk about instrument amps and cabs when the talk is about hifi. Two worlds, dont mix them. Then the room for missinterpretations is much much smaller. The rest i forget. It's easy, no distortion for hifi. No second, no third and no seventh, very easy.

 

[generic]

never talk about instrument amps and cabs when the talk is about hifi

I'm not trying to talk about instrument amps. I'm seeking persuasive charts for measuring and interpreting the characteristics of tube output, as predictable across a wide range of different use cases. These characteristics might be measured scientifically on any amp with an adjustable gain setting.

 

[Jimbob54]

I'm not trying to talk about instrument amps. I'm seeking persuasive charts for measuring and interpreting the characteristics of tube output, as predictable across a wide range of different use cases. These characteristics might be measured scientifically on any amp with an adjustable gain setting.

You want to see the fairies

Edit :

 

[generic]

see the fairies

If progress has been made in simulating tube distortion than progress might be made in measuring fine details, nuances, etc. We have vast computing resources today, and plenty of sophisticated visualization methods. Why must we stay frozen with old school charts?

 

[SIY]

This is completely missing the point. I fully understand both the guitar signal chain and the playback signal chain. The point is that having a tube in either chain results in a different tone and quality of sound. The differences are obvious with side-by-side comparisons.

If I run a signal through two different gain stages (you pick the gain), one tube and one solid state, and verify the frequency responses as essentially equivalent, then record music through them to generate two level-matched files, differing only in the choice of tube vs SS, would you be willing to post ABX logs showing you can actually detect the "obvious" differences?

 

[whazzup]

The bottom line: Tubes produce similar overtones and second or third order effects with both guitar amps and playback amps. This can be easily demonstrated. Tubes test poorly but have an integrated coherence to their distortion -- in my experience this is lost in the conventional audio charts (at ASR) and the quick rejections by some of "bad, bad tubes." Yes, tubes objectively suck. I don't dispute that and don't personally like them for many uses, but I want the SCIENCE to be complete as to why. I want to know what makes for "desirable" tube output versus muddy and "undesirable" tube output. To this end, I'm seeking more advanced measurements of 2nd and 3rd order effects, and presentations of those measurements.

My point is simply, when using any amp that 'measures poorly', it means that it's adding distortions (desirable or not is up to personal preference) on top of the captured distortions in the audio file.

I believe this process below takes place, do you agree or disagree with any of the steps below?

1. Musician uses guitar + guitar amp, produces music / tones / overtones / distortions and whatnots, all gets captured by mic, recorded as computer file. Agreed?

2. Someone else now listens to that audio file on an amp with 0.XX% distortions. He or she will be listening to that captured music with the captured distortions (of the performance) AND the distortions introduced by the amp. Agreed?

 

[whazzup]

Yes, I have experience with both types of amps. Guitar + solid state = often clean, dry, and brittle. Audiophile + solid state = often clean, dry, and brittle. Guitar + tube = smooth complex distortions and the ability to distort. Audiophile + tube = smooth complex distortions and often a perceived experience that is 'better than the numbers suggest.' [Per the panther vs. data in this Crack review.]

For any and all cases I want to see effective charts as to why tube amp distortion (e.g., the grass in the sawtooth charts) is routinely preferred over the grass or other factors with solid state products. I'm merely seeking charts to show meaningful differences. While I routinely check ASR reviews as a useful data point, the tube-related charts leave me wanting more. There are indeed pleasing tube amps and unpleasant tube amps. What makes them different?

What happens if you find a tube amp that doesn't exhibit noticeable distortions? Jump to 1:31 for the measured FR.

 

[solderdude]

This is completely missing the point. I fully understand both the guitar signal chain and the playback signal chain. The point is that having a tube in either chain results in a different tone and quality of sound. The differences are obvious with side-by-side comparisons.

Electric guitars generate very low volume sounds by having strings vibrate over magnets -- this is either sent through a clean amplifier or a distorted amplifier. The amplifier can use tubes or not. Tubes produce a different, smoother tone and at a predictably louder perceived volume.

Audiophile music sources are sent through either tube or non-tube amplifiers, but generally clean amplifiers (excepting Audio GD and a few others). The fringe characteristics (i.e., marginal distortion) with playback is predictably different between tube and non-tube amps.

The bottom line: Tubes produce similar overtones and second or third order effects with both guitar amps and playback amps. This can be easily demonstrated. Tubes test poorly but have an integrated coherence to their distortion -- in my experience this is lost in the conventional audio charts (at ASR) and the quick rejections by some of "bad, bad tubes." Yes, tubes objectively suck. I don't dispute that and don't personally like them for many uses, but I want the SCIENCE to be complete as to why. I want to know what makes for "desirable" tube output versus muddy and "undesirable" tube output. To this end, I'm seeking more advanced measurements of 2nd and 3rd order effects, and presentations of those measurements.

No distortion (or below audible limits) is always better for playback (as with HD also comes IMD) than with distortion. Tube distortion is quite popular with musicians because it ONLY distorts the guitar sound and not voices or other instruments. Why add HD, IM and FR alterations to instruments/voices that do not need it ?
Sure you can, if you like that. And some actually DO prefer/like it. Nothing wrong with that.
Claiming that tubes are 'better' is nonsense. That's the whole point.
Preferred may seem better to those that prefer it but claiming it IS better in a fidelity/music kind of way is not.
A question of choosing words.

Tubes do not contain magic properties that somehow can create or return 'musicality' that was supposed to be lost in the countless solidstate components it went through.

When your stereo sounds clean, dry, and brittle try to move to better speakers, headphones or room treatment
My systems are all SS and everyone of them sounds full bodied, smooth and pleasantly detailed. On recordings that are poorly made it sounds poor as well.

 

[tomtoo]

I'm not trying to talk about instrument amps. I'm seeking persuasive charts for measuring and interpreting the characteristics of tube output, as predictable across a wide range of different use cases. These characteristics might be measured scientifically on any amp with an adjustable gain setting.

Sure its easy, its called THD measurement. You can split it up into the parts of the harmonics, if you like to. For hifi its still easy, as low as possible.

 

[generic]

You can split it up into the parts of the harmonics, if you like to.

That is exactly the point here. Scientific interest has nothing to do with seeking accuracy (i.e., high fidelity), but how and why distortion qualitatively differs between production methods. There must be a better and more informative way to examine and present this.

 

[generic]

If I run a signal through two different gain stages

What happens if

One central goal is to understand what is in the intentional distortions typical of commercial tube amps, vs. solid state amps. Why? What is predictable? How can scientific charts better show why one implementation or form of distortion might be preferred over another? A clean tube amp and clean solid state amp would serve as control conditions for various levels of distortion.

 

[solderdude]

There must be a better and more informative way to examine and present this.

One central goal is to understand what is in the intentional distortions typical of commercial tube amps, vs. solid state amps. Why? What is predictable? How can scientific charts better show why one implementation or form of distortion might be preferred over another? A clean tube amp and clean solid state amp would serve as control conditions for various levels of distortion.

Education of what plots can actually tell you makes it more informative. Those that only see grass, have no real idea of audibility levels and the differences in different types of distortions and levels can easily draw the wrong conclusions.
The plots at ASR and elsewhere, IMO, are far more informative by those that measure, experiment, listen and understand plots than those that don't.

The informativeness thus depends on the one that is trying to be informed by looking at measurements.
technical savvy people simply get more info out of these plots and kind of know the limitations and consequences of certain measurements and what they can or cannot say about its performance when tested under specific conditions.

 

[Francis Vaughan]

Guitar + solid state = often clean, dry, and brittle. Audiophile + solid state = often clean, dry, and brittle. Guitar + tube = smooth complex distortions and the ability to distort. Audiophile + tube = smooth complex distortions and often a perceived experience that is 'better than the numbers suggest.'

I would say you are over generalising. Audio reproduction tube amps might add a little bit of euphonic distortion - and don't imagine there are not a lot of audiophile semiconductor amps that don't also try. But a tube guitar amp is distorting in a totally different manner. The grass in the sawtooth graphs will have grown to the top of the graph. It actually isn't all that hard to understand the nature of a guitar amp. But you have to start from it being part of an instrument. It acts in the total instrument in much the same way as a bow on a string acts, or as a vibrating reed acts. (It just happens in an unusual order.) The instrument is not finished. The speaker and cabinet are to come, and are also a critical part of the instrument. And like any instrument, the person playing it can make it sound fabulous or terrible. It isn't just some magic in the tube circuits.

There are aspects of euphonic sound that are not captured in the THD. IM is one, and IM is a very very wide question. For a guitar amp that includes things like power supply sag. You won't see that on a THD graph, but it is very much a part of the sound of some amps. Working out a euphonic distortion is a lot harder than eliminating distortion. Some is art, much is taste, and all involves luck and experience. Heck, slashing the speaker cone with a razor was once an established way of getting a desired tone.

Guitar players (and idiot audiophools) go tube rolling. Swapping out a gain stage 12ax7 for a 12au7 will drop the gain, and get you a totally different amp sound. If you didn't rebias the tube you also put the entire circuit out of whack in an uncontrolled manner. Some of the sound change is easy to define, some a crapshoot. And so it goes. Just swapping say a vintage Mullard for a Sovtek of the same notional type will change the sound - with most of that sound change not due to some magic sauce in the tube, but simply due to each tube being best suited to slightly different operating conditions, something that could be trivially fixed by checking the load lines and biasing it out. But then the tubes would sound the same, and where is the fun in that? I'm raving, but you get the idea.

In the end, one person's euphonic distortion can be another's harsh and brittle or slow and bloated. A lot will depend upon what you listen to. A real lot. Applying some simple harmonic theory can give you some clues as to what is happening. But beware. Just looking at the mix of odd and even harmonics isn't enough. There are iron clad rules about how the transfer function of an amplifer and these harmonics work that makes it much more messy than is usually appreciated. (And indeed why the simple THD and IM graphs can tell you when an amp is clean, but won't reliably tell you when a distorting amp will sound euphonic.)

 

[generic]

Those that only see grass, have no real idea of audibility levels and the differences in different types of distortions and levels can easily draw the wrong conclusions.
The plots at ASR and elsewhere, IMO, are far more informative by those that measure, experiment, listen and understand plots than those that don't.

Yep. However, over the last few years ASR has become incredibly influential (e.g., the rise of THX, the rise of Topping, shaping the Schiit product catalog, the recent PS Audio dust-up). If directed at audio engineers then the current charts and discussion might be fine. What troubles me is some of the earlier comments to the effect that tubes are garbage when they can be qualitatively very different (and pleasing to some). I strongly recommend that ASR consider the impact on social media (and thereby buying decisions). As with umpteen other industries, one must balance engineering with human factors and (ugg) marketing.

 

[generic]

In the end, one person's euphonic distortion can be another's harsh and brittle or slow and bloated. A lot will depend upon what you listen to. A real lot. Applying some simple harmonic theory can give you some clues as to what is happening. But beware. Just looking at the mix of odd and even harmonics isn't enough. There are iron clad rules about how the transfer function of an amplifer and these harmonics work that makes it much more messy than is usually appreciated. (And indeed why the simple THD and IM graphs can tell you when an amp is clean, but won't reliably tell you when a distorting amp will sound euphonic.)

Full agreement here. I'm by no means a tube defender for many use cases, and personally focus on audio neutrality/clarity with headphones and amps. Per my prior reply (#276), ASR's charts might consider the current expanded website audience. On another forum I encountered a newbie audiophile who added in every other sentence "This product doesn't test well at ASR so the vendor must be trying to improve it for ASR." No, not at all...

Measurements have little meaning for many users, and user preferences can vary dramatically between individuals (per human factors research). I believe we have the computing power to improve the scientific presentation of the messy and "euphonic" stuff. I put euphonics in quotes because I generally don't seek anything more than mild softening of harshness or mild tone control.

 

[tomtoo]

My point is simply, when using any amp that 'measures poorly', it means that it's adding distortions (desirable or not is up to personal preference) on top of the captured distortions in the audio file.

I believe this process below takes place, do you agree or disagree with any of the steps below?

1. Musician uses guitar + guitar amp, produces music / tones / overtones / distortions and whatnots, all gets captured by mic, recorded as computer file. Agreed?

2. Someone else now listens to that audio file on an amp with 0.XX% distortions. He or she will be listening to that captured music with the captured distortions (of the performance) AND the distortions introduced by the amp. Agreed?

Absolutly! Thats why opera singers usually dont like to sing through a marshall amp and cab. And thats why u usally also mic a akustik guitar direct and not trough a fender bass amp.

 

[tomtoo]

Yep. However, over the last few years ASR has become incredibly influential (e.g., the rise of THX, the rise of Topping, shaping the Schiit product catalog, the recent PS Audio dust-up). If directed at audio engineers then the current charts and discussion might be fine. What troubles me is some of the earlier comments to the effect that tubes are garbage when they can be qualitatively very different (and pleasing to some). I strongly recommend that ASR consider the impact on social media (and thereby buying decisions). As with umpteen other industries, one must balance engineering with human factors and (ugg) marketing.

Tubes in hifi power amps are economicly seen garbage for the buyer. At least if you only talk about sound.

 

[lashto]

No distortion (or below audible limits) is always better for playback (as with HD also comes IMD) than with distortion.

How about a multioption poll on that one (like 100%right/somewhat right/dont know/somewhat wrong/100% wrong) ?!

Or if you dont feel like it, may i use your words to create one?