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Headphone and Amp Impedance (2011)

nwavguy.blogspot.com

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Re: Headphone and Amp Impedance (2011)

#91

Post by snvzz »

mckirk wrote: post #90
snvzz wrote: post #71

Earlier quoted context omitted.

Sennheiser HD600 and Topping DX3Pro+[0] are the combination I recommend today. The Atom doesn't hold up as well as when it launched in today's market at that price point. That DX3Pro+ is a strongly measuring dac+amp single unit at the price. As for HD600, they're the time-proven, neutral, uncolored, accurate timbre kings. Great overall balance. 0. https://www.audiosciencereview.com/forum/index.php?threads/t...

The DX3 Pro+ seems like a great recommendation, I might have gone for that as well if it had been available when I was researching. And I concur regarding the HD600, it's a great choice for many people. I was trying out both a HD650 and the DT1990 before making my choice, and for me the 'precision' of the 1990s was just too enticing compared to the laid-back sound of the 650s -- but it was a hard choice, because some…

Note the HD650 are warm and laid-back not just relative to DT1990, but also relative to HD600.

Re: Headphone and Amp Impedance (2011)

#93

Post by shadowpho »

kragen wrote: post #58
shadowpho wrote: post #39

Earlier quoted context omitted.

What’s wrong with type c connectors? They are dirt cheap, psu/cable is already done for you, thoroughly tested, and easy to solder(6pin version)

usb c? they're fragile as shit, they're a pain in the ass to solder compared to 3.5mm jacks or rj-11 jacks, the data protocol is a fucking nightmare, making a compliant psu is even worse, 90% of the market consists of noncompliant devices that are thoroughly tested to not work, you have to insert them at the right angle, and, worst of all, here in argentina they aren't even dirt cheap basically in many ways usb c rep…

>they're fragile as shit.

Which part?

>data protocol is a fucking nightmare

How come? I’ve done many projects with type c and never felt that way. For basics (5v/1A) it’s just two resistors. For higher voltages I stick a pd controller that handles it.

Re: Headphone and Amp Impedance (2011)

#94

Post by kragen »

shadowpho wrote: post #93
kragen wrote: post #58

Earlier quoted context omitted.

usb c? they're fragile as shit, they're a pain in the ass to solder compared to 3.5mm jacks or rj-11 jacks, the data protocol is a fucking nightmare, making a compliant psu is even worse, 90% of the market consists of noncompliant devices that are thoroughly tested to not work, you have to insert them at the right angle, and, worst of all, here in argentina they aren't even dirt cheap basically in many ways usb c rep…

>they're fragile as shit. Which part? >data protocol is a fucking nightmare How come? I’ve done many projects with type c and never felt that way. For basics (5v/1A) it’s just two resistors. For higher voltages I stick a pd controller that handles it.

the pins on the usb-c connector are tiny, which makes them individually fragile, but also the connector inside the device is short, and usb-c cables invariably have a long semi-rigid strain relief to protect the cable from breaking, so the cable has a large lever arm to torque the connector off your pcb. it's a huge problem with micro-b jacks, which are about the same size. usb-c fixes some of the micro-b mechanical problems, but not that one

one problem with the usb data protocol is that it won't work over a bus; it requires point-to-point links. but, more generally, my complaint about the data protocol is this. i want two devices with no usb hardware, clocked at 8 megahertz ±10%, with a kilobyte or less of code memory, to communicate with each other. there are multiple reasons that is just never going to happen over usb. usb requires timing precision of ±0.5%, so a crystal or at least a ceramic resonator is mandatory (not a reasonable option on an 8-pin micro), and v-usb requires over a kilobyte of code memory to run at all. and even v-usb only provides a slave device! even if all your devices are avrs with crystals, you can't run a wire between two devices running v-usb and have them communicate. and bitbanging a usb master requires, as i understand it, several times more code (i've never done it)

also, v-usb won't let you do anything else while you're communicating; it needs every clock cycle

so, i want something that's about 3% or less of the complexity of the usb protocol, with timing specs that are 40 times more relaxed

i agree that if you only want power and not communication, and your durability requirements are not high, usb-c is a very practical option. and, even with communication, it's an even more practical option for connections at a larger granularity than what i'm talking about, where the devices involved are big enough for one of them to be a usb master. but that's a different order of magnitude: tens of kilobytes of ram on each endpoint, not tens of bytes

Re: Headphone and Amp Impedance (2011)

#95

Post by kazinator »

lelanthran wrote: post #66
kazinator wrote: post #36

Earlier quoted context omitted.

Unlike what other commenters are saying, this Zout == Zin is applicable to audio. For a fixed Zout much higher than zero, if we want to suck the most power out of the amplifier, we should use a matching Zin indeed. E.g. if an amplifier has 16 ohms output impedance, then we will draw the most power out of it with a 16 ohm load. Loads higher than 16 ohms will result in less current flowing. Loads lower than 16 ohms wil…

> In amplifiers we care about efficiency, That is at odds with what the blog post says. I'm now confused - for the best sound quality, are we to maximise efficiency of power usage or maximise accuracy of signal reproduction? I didn't think you can do both.

You are right. Audio amplifiers have not historically been power efficient.

In the case of a headphone amplifier on AC power, we don't have to think about efficiency, as long as it isn't ridiculous, like drawing 100W.

Class B amplifiers are only efficient when producing no output, or when producing output clipped to the power rails (like a square wave). Due to being almost fully off or fully on.

For a sinusoidal signal, the worst case efficiency occurs at about 40% of the output power delivered to the load, when the transistors will dissipate another 20%.

Source: https://eng.libretexts.org/Bookshelves/Electrical_Engineerin... Section 9.2.4: Class B Power Dissipation

Re: Headphone and Amp Impedance (2011)

#96

Post by tanseydavid »

dusted wrote: post #44

I find myself guilty of deep-diving into headfi-territory audiophilia once in a while, this time it got to me as well and I started thinking how neat it'd be to finally do it and get some high-end replacement for my 250 ohm dt990 pro cans, and I've heard both the hifman arya and sennheiser hd800s and know they are quite a lot better.. but THEN comes the amp question... and the rabbithole deepens.. and then the DAC an…

>> Of course, audiophilia is a sickness, and it never ends

Thank you for helping diagnose one of my obsessions for me.

Re: Headphone and Amp Impedance (2011)

#97

Post by em3rgent0rdr »

kragen wrote: post #59
em3rgent0rdr wrote: post #29

Earlier quoted context omitted.

Apple's iPod Shuffle 2G did charging and USB syncing over its 3.5mm TRRS socket. And for people concerned about accidentally shorting a power line when inserting the plug, hypothetically could use a socket with built in switches so power is only sent once the plug is fully inserted into the socket.

oh hey, that's a pretty good idea, thanks! you can tell i'm a novice it would still probably burn out my earbuds if i put 5 volts at 100 milliamps on the tip connector once the plug was fully inserted

oh ok, I understand your concern now "how do i keep from burning out headphones if someone accidentally plugs them in".

I am hesitant to give advice because I don't know a great way, but a possible method of detecting what type of device (a headphone or USB device) is plugged in could work by doing an impedance measurement right after the device is inserted. USB standard specifies that the signal-to-ground impedance on the data lines is 30 ohms and between data lines is differential impedance of 90 ohms. The right and left channel of headphones meanwhile have an impedance to ground (from 4 ohms to 32 ohms or higher), but aren't set to a differential impedance between the left and right channel. So maybe there is a simple circuit that could measure the differential impedance that is triggered just after a device is inserted, and if it matches 90 ohms, then will treat the device as a USB device, but if a measurement matches a headphone, then treat the device as a headphone. But the specifics on how to do this, I'm not sure.

Re: Headphone and Amp Impedance (2011)

#98

Post by kazinator »

kragen wrote: post #63
kazinator wrote: post #30

This business of damping or lack thereof, is really just a frequency response change. The concern with the resonance of the speaker is overblown. When you boost a frequency range electronically with an equalizer, that is also resonance (electronic rather than mechanical). Instead of your speaker ringing for a couple of cycles, the circuit is doing it.

a couple of cycles? q=2 isn't much of a resonance

There seems to be this idea circulating among some audiophiles that unless your amplifier has five digit damping factor, the speakers will ring like tympani drums, which is wildly exaggerated.

Re: Headphone and Amp Impedance (2011)

#99

Post by em3rgent0rdr »

em3rgent0rdr wrote: post #97
kragen wrote: post #59

Earlier quoted context omitted.

oh hey, that's a pretty good idea, thanks! you can tell i'm a novice it would still probably burn out my earbuds if i put 5 volts at 100 milliamps on the tip connector once the plug was fully inserted

oh ok, I understand your concern now "how do i keep from burning out headphones if someone accidentally plugs them in". I am hesitant to give advice because I don't know a great way, but a possible method of detecting what type of device (a headphone or USB device) is plugged in could work by doing an impedance measurement right after the device is inserted. USB standard specifies that the signal-to-ground impedance…

Also see figure 3 of https://www.onsemi.com/pub/collateral/and8074-d.pdf which gives a schematic of USB lines and says "if a 1.5 k pull up resistor is connected on either the D+ or D− line, the port is identified as upstream". Unfortunately downstream devices have pull-down to ground, so when not being driven would rest at low voltage, which I can't think of a great way to help to distinguish downstream USB from headphones.

Re: Headphone and Amp Impedance (2011)

#100

Post by marxisttemp »

itsoktocry wrote: post #88
0x008 wrote: post #87

Earlier quoted context omitted.

In my humble opinion the sound of the headphones is just preference. Of course some people will tell you the arya is great or the hd800s or whatever, but in the end it just is a sound preference. Do you prefer airy highs or warm mids or whatever the terminology is. When it comes to DACs and amps its just simple: get the one that has the best signal to noise ratio. Usually they should not alter the sound profile at al…

> Do you prefer airy highs or warm mids or whatever the terminology is. There is no terminology, that's the problem. What is "airy"? What is "warm"? You're right, subjective. We can only care about what can be measured.

Is your username a SOPHIE reference?
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