Early-stage "Introduction to audio" guide. Care to take a look, and possibly give your advice?

[Entropy.]

Hey, 

        TL;DR: I feel like there's not many great resources out there for new faces that are interested in audio to get started building their knowledge. I'm currently drafting a guide to try and help those that might need that information. Down below is the link to the very rough guide that I'm drafting. If you have any thoughts or opinions, I'm open to all suggestions, and if you have any ideas or want to contribute, The doc is open for comments. Thanks!

     The journey to where I am now in terms of knowledge in audio- specifically with headphones and speakers, as well as their associated accessories- wasn't an easy one. Searching through youtube, multiple forums, and just the interwebs, I was hard-pressed to find a competent guide that provided a proper, fact-based, and easy to understand introduction to audio. After finally finding people that could provide definitions and satiate my thirst to know, I looked back and found that there really weren't a ton of resources currently available to help guide those who are interested through the beginnings of this hobby. I am aware that there are resources such as the r/audiophile resource guide, however I feel like even that doesn't grasp all the subjects that I'm interested in, and can be confusing for newcomers. With that said, I want to help make that introduction to new audiophiles that are curious and learning about the hobby something that isn't remotely as confusing as how I beileve It was for me- bringing me to what I'm attempting to do.

 

     Currently, I'm drafting a guide that'll get most people regardless of technical knowledge up to speed on the facts that they need to know about audio. This includes the enormity of audio, Audio terms and what exactly this hobby is, and some general advice for people new to the hobby. This also includes more specific advice for people interested in headphone and stereo systems, as well as possibly adding amps, dacs, ect. to their setup. Finally, this guide will include an introduction to graphics/data and objective sources, and It'll address things such as room treatment, connections and cabling, and How various audio systems work together (Componentry, connections, ect.). Currently what I'm working on addresses the topics specifically mentioned above, as well as headphones and stereo speaker systems that will be used for listening and general use- not home theater systems-esque, surround-sound systems, microphones, or much of DIY audio. This is purely due to the limitations in my knowledge of these topics. 

 

With all that being said, by no standard am I extremely experienced or knowledgeable in this field, and I'm unsure if I've missed something. I'd love to hear your thoughts and opinions about this- and if you'd like, the doc is open for comments, if you'd like to contribute in any way shape or form that'd be really appreciated. Thanks!

Intro to audio subjects - Google Docs

[The_russian]

Looking forward to this. I'm interested in improving my audio setups but there is so much conflicting information, non-answers, and the biggest problem I've found: guides that use way too much technical jargon to be understood by someone just getting into the hobby. I'm not asking for an article that can be understood by an 8 year old, but if an introduction guide requires you to already have a good understanding of the topic to even know what is being talked about, it's not a very good introduction guide. Point is I want to get into the hobby, but it seems like a lot of effort to establish a good enough understanding to know what to buy and how to not get ripped off/misled by marketing.  

[rice guru]

I think covering genric terms like Warm, bright, midforward. and many ways to describe sounds would be a good section to have. Also one thing I would love covered from a few perspectives is properly powering gear. Im sure you have seen several argu8ments and debates about how much power you need on specific headphones and why having overhead on an amp is beneficial. things like gear synergy is something nice to cover as well. and if you need help with recommendations with headphone gear sub $500 as that's what I'm most comfortable with I would also be glad to help 

[Entropy.]

On 5/23/2021 at 6:02 PM, The_russian said:

Looking forward to this. I'm interested in improving my audio setups but there is so much conflicting information, non-answers, and the biggest problem I've found: guides that use way too much technical jargon to be understood by someone just getting into the hobby. I'm not asking for an article that can be understood by an 8 year old, but if an introduction guide requires you to already have a good understanding of the topic to even know what is being talked about, it's not a very good introduction guide. Point is I want to get into the hobby, but it seems like a lot of effort to establish a good enough understanding to know what to buy and how to not get ripped off/misled by marketing.  

Hey, Right now I'm drafting the general overview for the guide, and I just realized... I got into this hobby well over a year ago, and I understood the basics of audio for a decent amount of time before that. I don't really know a ton of the basic questions that somebody that is less familiar with the field might have. So er, I think you know where I'm going with this. Do you have any just general, broad questions about the hobby? Maybe something you're a little foggy on, or just something that you heard about online somewhere? No matter how broad or seemingly obvious- or on the flipside, obscure and niche, the question, I would really appreciate the feedback. Perhaps maybe even things you already know, honestly anything. I'd love any help you could provide, if you'd be willing.

 

On 5/23/2021 at 6:08 PM, rice guru said:

I think covering genric terms like Warm, bright, midforward. and many ways to describe sounds would be a good section to have. Also one thing I would love covered from a few perspectives is properly powering gear. Im sure you have seen several argu8ments and debates about how much power you need on specific headphones and why having overhead on an amp is beneficial. things like gear synergy is something nice to cover as well. and if you need help with recommendations with headphone gear sub $500 as that's what I'm most comfortable with I would also be glad to help 

Hi there, I wanted to ask you for help as well, just in a slightly different vain. Are there any "beginner" -esque questions that you think are underrepresented in the community, or maybe is there stuff you just see getting asked over and over again? And if so, do you mind sharing them with me? Thanks a million.
 

Thanks to both of you

[The_russian]

1 hour ago, Brok3n But who cares? said:

Do you have any just general, broad questions about the hobby? Maybe something you're a little foggy on, or just something that you heard about online somewhere? No matter how broad or seemingly obvious- or on the flipside, obscure and niche, the question, I would really appreciate the feedback. Perhaps maybe even things you already know, honestly anything. I'd love any help you could provide, if you'd be willing.

Here's a list of questions that either I currently have, have had at one point, or just questions in general in no particular order. Hope some are useful or at least help you think of other topics/questions to cover. I want to start looking into a good headphones setup at some point, but so far I have been getting into speaker/loudspeaker setups with a home theater and a 2.1 setup for my computer, so if it seems like there are more questions about speakers than headphones, that is why. 

 

• What is the audible difference in sound quality in terms of bit depth and sample rates? Obviously higher is better and there are diminishing returns, but more of how do the higher quality files actually sound better? Do higher and/or lower frequencies in particular sound better? Does the sound have more clarity in general? 
• You're probably already covering this, but overview of bit depth and sample rate. 
• What are the differences in a headphones setup vs speakers? Probably personal preference, but in general why would one be preferable over the other? Does one make more sense than the other for certain budgets? Does one give a better audio experience and/or quality?
• Do certain music genres benefit more from a hifi setup than others? For example rock, pop, EDM. How about time periods? Do older songs (for example from 60s - 80s) benefit more from higher quality audio, or is it just that the people more likely to have the money to spare on good audio are often older and grew up listening to those songs? 
• What should I look for when looking for a subwoofer? If I just look at specs such as woofer size, amp wattage, frequency response, and max dB output (loudness), it seems like relatively cheaper subs often have similar specs for the above (size, wattage, etc.) on paper as more expensive subs. What makes the better subs better? Are the cheaper ones just lying about their true specs? (I'm sure that is the case for many of them, but this also applies to bigger companies that I wouldn't expect to list incorrect specs).
• On the topic of subs, front-firing vs down-firing, advantages and disadvantages. Is one better than the other in certain rooms or setups? Is one preferable in general?
• Sticking with subwoofers do you always need a sub for a good listening experience? When would you/would you not? Mostly applies to music not home theater, and assuming a decent budget (not $100 for a setup)
• Is matching a subwoofer to speakers important or even a thing? For a home theater you want to match the sound qualities of front speakers and center speaker so you get a consistent sound, particularly when sound moves left to right or right to left. Does something similar apply to matching the sound characteristics of a subwoofer with speakers for a 2.1 setup used for listening to music?
• Preamp, power amp, A/V receiver. What does each one do, what are the benefits of getting dedicated preamp and power amp, when (at what general price point or user case) does it make most sense to switch from AV receiver to separate components
• How do you know what sound qualities you prefer, which will in turn influence what speakers you choose? Do you go to an audio shop and test out a bunch of different speakers and setups? Do you just go through different iterations every few months/years until you settle on something you like? 

[H713]

I'm currently working 60 hours a week, so I'm relatively limited in how much time I have to work on this. 

 

-I don't see much need to talk about amplifier classes in this. People can research that if they really care. Fact of the matter is, it's a useless generalization and even well-respected engineers differ on terminology. If people want to know about amplifier classes, go to the ESP site or buy Douglas Self's book on power amplifiers.

 

-The issues of DAC information is a constant question, particularly with regard to sample rates, but also in bit depth. The big disconnect between most people on the LTT forum, and the reality of this issue, is that these numbers mean almost nothing about device performance because the limiting factor is almost always in the analog domain (very often grounding / PCB layout related). Also worth taking the time to point out that DACs are generally the most ideal part of the audio chain, with some onboard audio having better THD+N numbers than many power amplifiers.

 

-Impedances, sensitivity and amplifier power. Another constant question, related to how hard a particular pair of headphones is to drive. NwAvGuy did a pretty decent writeup on this that may be useful.

 

-In order to understand any specs or graphs, it's necessary to understand the decibel scale. This is another really common area where beginners get confused, particularly since there are a lot of units that look similar but mean very different things. For example, dB, dB SPL, dBA, dBu, dBv, dBFS and dBm all mean different things and are not interchangeable. The Wikipedia page for "decibel" covers this, two thirds of the way through the article, after some math that looks scarier than it really is. Helpful for the engineer who forgot WTF dBZ is, less helpful to someone just getting started in audio.

 

-Help make priorities clear based on what really matters. For example, most will agree that for speakers, room acoustics, then speakers, then amplifiers, then DACs. The first two (speakers and room acoustics) trade blows for importance, but amplifiers and DACs are much less noticeable unless they are broken or inappropriate for the task. For headphones, it would be headphones, then headphone amplifiers, then the DAC. Source files fit in somewhere after transducers and room acoustics, but after DACs. The point is to emphasize what parts of the chain are least ideal, and which ones are most ideal. 

 

-Briefly discuss the issues of balanced interconnects (which usually use XLR or TRS connectors) and balanced headphone outputs. Discuss the benefits of balanced interconnects. Make sure to note that the advantage of balanced headphone outputs is an increase in output power (from the same rail voltage) and nothing more, since this is a common misconception

 

-Tube amps. At some point somebody is going to need to tackle a section on one of the most commonly misunderstood pieces of audio equipment. A lot of this is going to come down to the fact that the performance of tube amps is highly variable, with some sounding almost the same as a good solid-state amp and others being distorted messes that are still fun to play with. 

 

-I see quite a lot of posts from people asking about XXXX vintage receiver / amplifier. There seem to be three questions people ask. They want to know if it's any good, how to hook it up to a modern computer or TV, and how to go about recapping / restoring it. 

 

-I think that it's worth taking a couple sentences to explain what DIY audio is as a hobby, since it's closely related. 

 

I think this is a great project, but it's one that could easily be an entire book. I think that the most useful thing for a lot of these will be to find some good web resources to link to. A few useful resources that may be useful:

 

The ASR Youtube channel has a few videos that do a reasonable job of explaining how to read measurements:

https://www.youtube.com/channel/UCWp1NY1KXGwcOh1RxKp_-FA/videos

 

Excellent writeup on grounding in the audio system:

https://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf

 

Some useful articles from the NwAvGuy blog:

http://nwavguy.blogspot.com/2011/02/headphone-impedance-explained.html

 

http://nwavguy.blogspot.com/2011/02/headphone-amp-impedance.html

 

 

[rice guru]

3 hours ago, Brok3n But who cares? said:

Hey, Right now I'm drafting the general overview for the guide, and I just realized... I got into this hobby well over a year ago, and I understood the basics of audio for a decent amount of time before that. I don't really know a ton of the basic questions that somebody that is less familiar with the field might have. So er, I think you know where I'm going with this. Do you have any just general, broad questions about the hobby? Maybe something you're a little foggy on, or just something that you heard about online somewhere? No matter how broad or seemingly obvious- or on the flipside, obscure and niche, the question, I would really appreciate the feedback. Perhaps maybe even things you already know, honestly anything. I'd love any help you could provide, if you'd be willing.

 

Hi there, I wanted to ask you for help as well, just in a slightly different vain. Are there any "beginner" -esque questions that you think are underrepresented in the community, or maybe is there stuff you just see getting asked over and over again? And if so, do you mind sharing them with me? Thanks a million.
 

Thanks to both of you

If you could convert what impedance means, why it matters, like the relationship between out put impedance on an amp and the impedance of a headphone. What sensitivity is. And how sensitivity is measured and how sensitivity of a headphone isn't even a great way of telling you how hard it is to power. And how nuanced powering a headphone is even something as powering something as popular as a 650 is a complicated topic due to how notoriously hard to power certain frequencies are and there is even measurable proof like this 

[Derkoli]

10 hours ago, Brok3n But who cares? said:

Are there any "beginner" -esque questions that you think are underrepresented in the community, or maybe is there stuff you just see getting asked over and over again?

"How much power do my headphones need?" is a big one I see alot. Most beginners tend to see "high impedance = hard to drive" then follow that. Which obviously ain't true.

 

Another thing is the difference between driver types.

 

Here's a list of all the driver types I can think of:

 

Plasma arc - Pretty rare, related to Ion Thrusters for spacecraft. Kits available for purchase @ https://www.imagesco.com/kits/plasma-speaker.html

 

Radialstrahler - Very rare. Only the company MBL really makes them (I currently own a pair of Radialstrahler speakers, and they're excellent)

 

Piezo - Only really used as tweeters in cheap speakers, and for little buzzers and what-not.

 

X-ART - Older S-ART by Adam Audio

 

S-ART - Newer X-ART by Adam Audio

 

U-ART - Cheaper version of the S-ART, mostly based on the X-ART AFAIK.

 

Ribbon - A thin foil diaphragm (usually aluminium) is suspended between two magnets. A high voltage audio signal is then passed over the diaphragm. Which then makes it vibrate, creating sound. Needs to be paired with a transformer on its input, as an audio amplifier does not have the voltage required to get it moving.

 

AMT - Doesn't require high voltage. Effectively squeezes and pulls the diaphragm apart, which creates pressure in the folds of the diaphragm. This then creates sound.

 

Dynamic - Your classic driver. In both the cheapest speakers, and also some of the most expensive. Uses a voice coil that the audio signal runs through to make the diaphragm move back and forth to create sound.

 

Planar Magnetic - Similar to Electrostatic, but the diaphragm has the audio signal running through it, and is sat in a permanent magnetic field. So the voltage makes the diaphragm vibrate.

 

Electrostatic - The diaphragm holds a constant voltage, and the flipping charge of the two plates it's surrounded by makes the diaphragm vibrate, creating sound. Made primarily by Martin Logan. Typically need a large surface area to create enough SPL.

 

Magnetostatic - Same as Electrostatic, but uses high current instead of high voltage.

 

Magnetostrictive - Made by Feonic, which is a spinoff of Hull University. This same effect is what creates the "electric hum" you can hear near things like transformers.

 

Rotary woofer - Essentially a large fan spinning, and each blade changes pitch in accordance to the audio it's receiving. Operate down to 0 Hz and up to roughly 30 Hz. Require a VERY large backwave chamber, which is usually an entire room.

 

Digital transducer - pretty much not used

 

Bending wave - Rare, made by Manger and incorporated into speakers by Ohm Walsh.

 

Moving iron - Used in some earphones and PC speakers.

 

Balanced Armature - Used in IEM's.

[rice guru]

2 hours ago, Derkoli said:

"How much power do my headphones need?" is a big one I see alot. Most beginners tend to see "high impedance = hard to drive" then follow that. Which obviously ain't true.

 

Another thing is the difference between driver types.

 

Here's a list of all the driver types I can think of:

 

Plasma arc - Pretty rare, related to Ion Thrusters for spacecraft. Kits available for purchase @ https://www.imagesco.com/kits/plasma-speaker.html

 

Radialstrahler - Very rare. Only the company MBL really makes them (I currently own a pair of Radialstrahler speakers, and they're excellent)

 

Piezo - Only really used as tweeters in cheap speakers, and for little buzzers and what-not.

 

X-ART - Older S-ART by Adam Audio

 

S-ART - Newer X-ART by Adam Audio

 

U-ART - Cheaper version of the S-ART, mostly based on the X-ART AFAIK.

 

Ribbon - A thin foil diaphragm (usually aluminium) is suspended between two magnets. A high voltage audio signal is then passed over the diaphragm. Which then makes it vibrate, creating sound. Needs to be paired with a transformer on its input, as an audio amplifier does not have the voltage required to get it moving.

 

AMT - Doesn't require high voltage. Effectively squeezes and pulls the diaphragm apart, which creates pressure in the folds of the diaphragm. This then creates sound.

 

Dynamic - Your classic driver. In both the cheapest speakers, and also some of the most expensive. Uses a voice coil that the audio signal runs through to make the diaphragm move back and forth to create sound.

 

Planar Magnetic - Similar to Electrostatic, but the diaphragm has the audio signal running through it, and is sat in a permanent magnetic field. So the voltage makes the diaphragm vibrate.

 

Electrostatic - The diaphragm holds a constant voltage, and the flipping charge of the two plates it's surrounded by makes the diaphragm vibrate, creating sound. Made primarily by Martin Logan. Typically need a large surface area to create enough SPL.

 

Magnetostatic - Same as Electrostatic, but uses high current instead of high voltage.

 

Magnetostrictive - Made by Feonic, which is a spinoff of Hull University. This same effect is what creates the "electric hum" you can hear near things like transformers.

 

Rotary woofer - Essentially a large fan spinning, and each blade changes pitch in accordance to the audio it's receiving. Operate down to 0 Hz and up to roughly 30 Hz. Require a VERY large backwave chamber, which is usually an entire room.

 

Digital transducer - pretty much not used

 

Bending wave - Rare, made by Manger and incorporated into speakers by Ohm Walsh.

 

Moving iron - Used in some earphones and PC speakers.

 

Balanced Armature - Used in IEM's.

damn the differences between driver types are so nuanced they have to be experienced. Its really hard to interpret differences with words or charts fully that for a full experiece especially discerning between driver types it needs to be experienced. 

Also I mean in regards to how much power something needs I think other people also try to reduce it to measured sensitivity and even then the conversation is a little more nuanced than that as there are flaws down to how sensitivty is measured. 

[The Flying Sloth]

I just had a quick look through,

While perhaps slightly outside your area of expertise, mentioning Audio Interfaces as an alternative to purchasing a standalone DAC if the user is wanting to upgrade their microphone or even just using an interface instead of DAC for price/performance reasons. If you're looking to borrow any content about microphones or interfaces feel free to nick it from the guide in my signature.

I'll have a deeper look when I get the time but the only other thing that jumped out at me is that you've not yet written the section about used audio gear, the used market is something I have quite a lot of experience in and should be something very prominently displayed in your guide, especially when considering purchasing speakers. When you get to writing that bit, if you're looking for any info feel free to shoot me a message.

[H713]

Used gear is especially worthwhile when it comes to power amplifiers. I'm not aware of any amplifiers under $350 that I would really recommend, but there are tons of excellent power amps on the used market, many of which are available for practically nothing (you can get a really good power amplifier on the used market for $250).

 

@Derkoli Isn't a ribbon driver an extremely low impedance device requiring lots of current, rather than high voltage? You might be mistaking it for an electrostatic design, which traditionally does require extremely high voltage (and a step-up transformer). 

 

Also, has anyone actually developed a plasma speaker that is even remotely useful / practical? I know we've played around with driving flyback coils with an AM modulated signal from a big amplifier as a physics demonstration, but short of making everyone at a science fair flock to the booth set up by the plasma physics department, I struggle to see a use.

[The Flying Sloth]

4 hours ago, H713 said:

Also, has anyone actually developed a plasma speaker that is even remotely useful / practical? I know we've played around with driving flyback coils with an AM modulated signal from a big amplifier as a physics demonstration, but short of making everyone at a science fair flock to the booth set up by the plasma physics department, I struggle to see a use.

Magnat made plasma ion tweeters in the 70s and Acapella still makes them iirc. As for true, full-range plasma speakers, I don't recall any being commercially available but I may be wrong.

[Derkoli]

15 hours ago, H713 said:

 Isn't a ribbon driver an extremely low impedance device requiring lots of current, rather than high voltage? You might be mistaking it for an electrostatic design, which traditionally does require extremely high voltage (and a step-up transformer).

Alot of ribbon drivers are laid out like this:

 

 

And usually, most Ribbon speakers use Dynamic drivers below 1-2 kHz ish, as you need alot of surface area to produce bass when using a Ribbon. Which tends to lead to distortion.

 

15 hours ago, H713 said:

Also, has anyone actually developed a plasma speaker that is even remotely useful / practical? I know we've played around with driving flyback coils with an AM modulated signal from a big amplifier as a physics demonstration, but short of making everyone at a science fair flock to the booth set up by the plasma physics department, I struggle to see a use.

AFAIK, Acapella is the only company that still makes ready built, high-end Plasma speakers. They're supposed to be quite good. They're also the only company that are certified for Health/Safety by the EU, because their Plasma tweeters don't produce any harmful by-products, as they don't make Ozone from ionizing Helium. They also claim to have invented the Spherical Horn, which is a bit iffy.

 

Specs of their Plasma tweeter:

 

 

The speakers it is implemented in are pretty efficient, at 95dB-100dB per Watt at 1M. But I assume they measure at 1 kHz, which is below what the tweeter will handle.

 

Another company called Magnat were the first guys to chuck a Plasma driver into a commercially available speaker. But they have moved back to more traditional drivers now. Magnat still makes some pretty cool products, like the smallest THX Ultra 2 certified subwoofer.

 

11 hours ago, The Flying Sloth said:

As for true, full-range plasma speakers, I don't recall any being commercially available but I may be wrong.

This company called Sonarc have claimed to have made a full range Plasma speaker. But it looks real iffy.

 

http://sonarcinnovations.com/

[H713]

The transformer is used as an impedance matching device so that it can be driven by a normal power amplifier. The voltage across the ribbon is tiny. It's much like a ribbon microphone being used in reverse (though obviously a bit beefier).

 

The physics behind a ribbon driver isn't all that different from a traditional electrodynamic driver. Both rely on the same principle. 

http://labman.phys.utk.edu/phys222core/modules/m4/The magnetic force.html

 

The voltage potential on the ribbon doesn't matter- it's the current passing through the ribbon that matters. 

 

Since traditional power amps behave like a very low-impedance voltage source, the ribbon, which is essentially a dead short, would trip the protection circuit in an amplifier almost intstantly. 

 

 

An electrostatic loudspeaker is a high-impedance voltage-driven device that is essentially a capacitive load. Ideally, you'd drive your electrostatic loudspeaker directly from a custom-designed tube (valve for the rest of the world) amplifier, which wouldn't use an output transformer. Obviously you need to know what you're doing if you're going to attempt this.

 

[HenrySalayne]

4 hours ago, H713 said:

which wouldn't use an output transformer.

It mustn't have an output transformer. Electrostatic loudspeakers need a bias voltage exceeding the actual signal several times to work with only little distortion.

 

@Brok3n But who cares?
Maybe you should start with a glossary so you don't have to explain every word you are writing. The current list of things will already fill a few dozen pages with text.

[ShearMe]

On 5/25/2021 at 3:08 AM, rice guru said:

If you could convert what impedance means, why it matters, like the relationship between out put impedance on an amp and the impedance of a headphone. What sensitivity is. And how sensitivity is measured and how sensitivity of a headphone isn't even a great way of telling you how hard it is to power. And how nuanced powering a headphone is even something as powering something as popular as a 650 is a complicated topic due to how notoriously hard to power certain frequencies are and there is even measurable proof like this 

 

What are you even trying to say? Is this a question or a statement?

 

[rice guru]

2 hours ago, ShearMe said:

What are you even trying to say? Is this a question or a statement?

 

Sorry this was a very unclear late night statement. I wanted the subject or powering a headphone covered  how  important it is. While also covering the nuances of it. I also want to cover sensitivity and how it's measured as well and how sensitivity is also not end all and be all of drivability.

[H713]

18 hours ago, HenrySalayne said:

It mustn't have an output transformer. Electrostatic loudspeakers need a bias voltage exceeding the actual signal several times to work with only little distortion.

 

@Brok3n But who cares?
Maybe you should start with a glossary so you don't have to explain every word you are writing. The current list of things will already fill a few dozen pages with text.

It could use an output transformer, depending on how that transformer is configured. It would not necessarily be a step-down. All of this depends on the design of the ESL and the choice of tubes. Of course, designing a good output transformer that also holds off 10 kV is a royal PITA.

 

More on topic, I think a glossary is absolutely essential for something like this. Additionally, I think you'll want to have a "further reading" section with links to useful sources.