Headphone Amps

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Headphone Amps

Post by ITHertz »

Hi All,

I mostly do editing and post work so I spend quite a bit of time using headphones (HD650s). Currently, the headphones are running off the headphone output of a Scarlett 18i20.

While looking at higher-end headphones I've come across quite a few articles that recommend using a dedicated headphone amp, particularly with higher impedance headphones like the HD650s. And something that surprised me a bit as I dip a tentative toe into the "audiophile" world is that a lot of these amps aren't particularly expensive (e.g. the Atom Amp+ here https://jdslabs.com/product/atom-amp/).

So I have a few questions about headphone amps in general - anyone using one? Do you think they provide better headphone performance compared with those built into interfaces (I know this probably varies a lot across different brands)?

Or am I at the top of a slippery slope leading into "audiophile land" and the next thing I'll be asking about is special mains cables :lol:

Cheers,

Chris
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Re: Headphone Amps

Post by Bob Bickerton »

Some years ago I bought a Lehmann Audio Studiocube which I think was recommended by folk around here. I was using HD650 headphones then and there was a minor improvement over whatever audio interface headphone output I had at that time.

More importantly, I liked the fact that I could have it a little remote to the AI, it had a nice big knob (not Mackie), two outputs and a mono switch.

I'm using lower impedance Beyer headphones these days and whilst I haven't done a serious A/B, I'm guessing there would be little difference relative to the headphone out on my Drawmer monitor controller.

All of which is probably not helping you at all!

Bob
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Re: Headphone Amps

Post by James Perrett »

High impedance headphones are easier to drive in most respects than low impedance headphones. They require less current and you can even drive them from a good line output at a pinch. The one issue with them is that they require more voltage for an equivalent sound level compared to low impedance headphones but it is usually fairly obvious when a headphone output is struggling to deliver sufficient volume without distorting.

Having said that, there are very slight audible differences between low budget headphone outputs but, personally, I wouldn't go spending large amounts of money on a headphone amp.
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Re: Headphone Amps

Post by forumuser931182 »

I would think that the Scarlett has quite a capable headphone amplifier that is up to the standard you would be happy with.
I have an Apogee One interface that I too feed into a Lehmann headphone amplifier however the audible difference I hear probably comes about because the Apogee has a 30 ohm output and I’m using 32 ohm Beyer headphones. I particularly find this with a different work computer where I use a Tascam interface. It’s headphone out is around 80 ohms I believe and the additional headphone amp is a major improvement.
Most headphone amps use low distortion high output opamps, fairly easy to put together so quite cheap to make. There are plenty of “hifi” headphone amps with discrete semiconductors, even valves for “that” sound.
As the first reply mentioned having a simple dedicated volume knob on a headphone amp is handy but with the Scarlett this may be all you gain. Maybe try before buy if you can.
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Re: Headphone Amps

Post by ITHertz »

I found this info online:

- For all 1st Gen, 2nd Gen, and 3rd Gen Bus-Powered Scarlett interfaces (Solo, 2i2, 2i4, and 4i4), iTrack Solo and Saffire 6 USB look for headphones with a maximum impedance of 200 ohms.

- For all 1st Gen, 2nd Gen, and 3rd Gen mains powered Scarlett interfaces (6i6, 8i6, 18i6, 18i8 and 18i20) look for headphones with a maximum impedance of 250 ohms.

- For all Clarett Interfaces (Clarett Thunderbolt, Clarett USB and Clarett+) and Red (Thunderbolt) interfaces, headphones with impedances of up to 600 ohms will be fine.

The HD650s are 300 ohm so it would appear that they're not an ideal match for the 18i20.
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Re: Headphone Amps

Post by forumuser931182 »

The output impedance of the amp doesn’t need to match the headphones. The smaller it is the less power you will lose through it and the less the amp will affect speaker response.
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Re: Headphone Amps

Post by sonics »

Headphone outputs do matter if you rely on them. As well as needing to provide enough voltage to attain the required listening levels, they need to work correctly with your chosen headphones. There are also the issues of pure audio quality and stereo balance.

Some cheaper interfaces struggle with these things. For example, I think that (as well as providing more power) the Clarett headphones outputs sound better than those on the Scarlett interfaces I've used. I have heard many other examples of sub-quality headphone outputs.

If you are doing detailed post editing (as I do) then the better clarity you can get the easier it is to hear what you're working on; this is a critical listening job.

I would consider a better headphone amp myself, and yes, you only need spend about $100 or so to get one.
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Re: Headphone Amps

Post by Hugh Robjohns »

ITHertz wrote: Fri Dec 02, 2022 7:13 amThe HD650s are 300 ohm so it would appear that they're not an ideal match for the 18i20.

In general terms, the higher the impedance the lower the maximum output level... but if it's more than loud enough with your current headphones and you've got sufficient detail and transparency
I wouldn't worry about a separate amp.

On the other hand, if you're struggling to get enough volume, or you're struggling with the detail, a new high-quality mains-powered headphone amp designed for higher-impedance phones might be beneficial.
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Re: Headphone Amps

Post by ITHertz »

At the moment, loudness isn't an issue however the question of detail is what concerns me a bit. Without actually trying a headphone amp it's hard to know if I'm missing something with my current setup.
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Re: Headphone Amps

Post by ITHertz »

sonics wrote: Fri Dec 02, 2022 4:55 pm Headphone outputs do matter if you rely on them. As well as needing to provide enough voltage to attain the required listening levels, they need to work correctly with your chosen headphones. There are also the issues of pure audio quality and stereo balance.

Some cheaper interfaces struggle with these things. For example, I think that (as well as providing more power) the Clarett headphones outputs sound better than those on the Scarlett interfaces I've used. I have heard many other examples of sub-quality headphone outputs.

If you are doing detailed post editing (as I do) then the better clarity you can get the easier it is to hear what you're working on; this is a critical listening job.

I would consider a better headphone amp myself, and yes, you only need spend about $100 or so to get one.

You've hit the nail on the head!

In the info I posted about the various Focusrite interfaces it's noticeable that the Clarett range are recommended for headphones up to 600 ohms, so it's likely that they're at least "different" in some way.

And I've also heard that headphone outputs are an area where cheaper interfaces cut corners. Not saying that's the case with the Scarlett but I imagine it could be.

Are you using a separate headphone amp and if so, what kind?
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Re: Headphone Amps

Post by sonics »

ITHertz wrote: Fri Dec 02, 2022 10:30 pm In the info I posted about the various Focusrite interfaces it's noticeable that the Clarett range are recommended for headphones up to 600 ohms, so it's likely that they're at least "different" in some way.

Where I live the cheapest Clarett is three times the price of the cheapest Scarlett. I'm sure that has an impact on the quality of the electronics, including the headphone circuitry. The main Clarett output also sounded noticeably better to me than the Scarlett (gen 2) when I compared them.

If your hearing and headphones are good enough (and the 650's are excellent), you may hear a difference too. I usually use an RME interface, which sounds great to me. I also have a PreSonus Studio series USB interface, which sounds very good too.

Put simply, better monitoring means it's easier to hear what you're doing, but you probably know that! :)
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