[Mcp1]

I am looking to dive in and buy a decent pair of open back headphones. A dedicated headphone amplifier is probably in my future, but for the time being, I was hoping to use my Belles Aria integrated’s headphone output. The only spec I an find is:

600 milliwatts into 30Ω peak

I guess I am wondering if there is maximum impedance that I will be facing when trying to decide on new headphones. Can anyone help me understand what to be looking for?

Thanks.

 

[Me x3]

That spec alone means very little.
My advice is to get the right headphone according to your preferences. Then start thinking about the amp.

What type of sound are you looking for?

 

[onevstheworld]

Impedance matching means picking an amp that has an output impedance less than 1/8th of your headphone's impedance... i.e. if your HP is 32 ohms, your amp's output impedance should be less than 4 ohms.

I don't have any experience with your amp, but several things make me suspicious that your Belles Aria may not be very versatile as a H-amp:

• it's marketed primarily as a speaker amp... unless it's got a dedicated circuit for the H-amp, these usually have a very high output impedance. If that number isn't available, it's possibly embarrassingly high. This would be less than ideal for low impedance phones... e.g. portable headphones and IEMs.
  
• it's H-amp output is rated at 600mW @30 ohms (peak)... which results in approx 400+mW RMS @30 ohms. That's not much power for a desktop amp. They don't publish numbers for higher HP impedance, but output power tends to decrease as HP impedance increases. For comparisons, Schiit Magni 3 is 2W @32 ohms, and even a portable amp like ifi iDSD BL is 950mW @32 ohms. Low sensitivity HP's are likely to struggle.
  
• the 2 above combined means many planar magnetic HP's (which tend to be low impedance, low sensitivity) won't be driven well. Classic example being Fostex T50rp.

Best approach would be to contact the company to get more specs. If they don't have those numbers, I'd be very pessimistic. But you can always try it out, then get a dedicated H-amp if you find it unsuitable.

 

[Nick 214]

I would recommend deciding on the cans first, trying them out, then looking into a new amp if you feel it necessary.

Jump in with both feet, and get to listening!

 

[ProtegeManiac]

600 milliwatts into 30Ω peak

I guess I am wondering if there is maximum impedance that I will be facing when trying to decide on new headphones. Can anyone help me understand what to be looking for?

Doesn't tell you a whole lot. At best, as load impedance rises (or sometimes, if it's lower than 32ohms or 16ohms), power output also goes down. Most high impedance headphones compared to their low impedance competitors tend to have higher sensitivity so that is usually compensated for. At the same time, speaker amps/preamps tend to have very high output impedance on their headphone output, and higher impedance headphones are less severely affected, so high impedance headphones are generally safer unless voltage performance isn't up to snuff that the sensitivity can't compensate for the severe drop in output.

That said, for the most part, if you're planning to get high impedance headphones, the less severe effect of lowered damping factor means that you're not really altering the sound, so what you hear will basically not be far off from a dedicated headphone amp, so if you like the sound, then at least you've pretty much heard what they really sound like. You will likely hear differences with a better headphone amp if you listen loud, but the thing is, with low impedance (let alone those with lower sensitivity and need more power), it's hard to tell if you just don't like the sound as driven by an integrated amp that likely has high output impedance or the headphone itself.

 

[Mcp1]

Thanks to all for the advice.

 

[Caribou679]

Impedance matching means picking an amp that has an output impedance less than 1/8th of your headphone's impedance... i.e. if your HP is 32 ohms, your amp's output impedance should be less than 4 ohms.

• They don't publish numbers for higher HP impedance, but output power tends to decrease as HP impedance increases. For comparisons, Schiit Magni 3 is 2W @32 ohms, and even a portable amp like ifi iDSD BL is 950mW @32 ohms. Low sensitivity HP's are likely to struggle.
  

I am confuse about the comment that output power decreases as HP impedance increases. On the Schiit Magni 3 website it is stated like that but on the Little Dot MK IV specs it is the reverse. Less HP impedance less power.
There is something I do not get ?

Little Dot MK IV specs

Technical Specifications:

• SEPP (Singled-ended Push Pull) OTL in Class-A
• Frequency response: 10 hz~100 Khz (-1dB)
• THD+N: 0.1% (100 mW @ 300 ohm)
• Power Output:
• 500 mW @ 300/600 ohm
• 300 mW @ 120 ohm
• 100 mW @ 32 ohm
• Power Consumption: 30W (228V x 0.133A)
• Variable Gain: 3,4,5, or 10x
• Recommended Load Impedance: 32 ohm~600 ohm
• Input Impedance: 50K ohms
• Pre-Amplifier Output Impedance: 600 ohms
• Pre-Amplifier Gain: 3-10x (also controlled via gain switches)
• Pre-Amplifier Voltage: 10V RMS

 

[ProtegeManiac]

I am confuse about the comment that output power decreases as HP impedance increases. On the Schiit Magni 3 website it is stated like that but on the Little Dot MK IV specs it is the reverse. Less HP impedance less power.
There is something I do not get ?

An Output Transformerless tube amplifier biases its output profile to high impedance loads. Max output is typically at 300ohms, and 600ohm output is still higher than what it can spit out at 32ohms. Only this amp design behaves in this matter, and among all other topologies, even if it's push-pull, it has a tendency to be the worst in current delivery vs solid state, hybrids, or transformer-coupled tube amps (whether PP or SET).

Here's another example.

By contrast, here's the Lyr 3 with 9watts per channel into 16ohms, then drops to 600mW per channel into 300ohms.

 

[Caribou679]

So the power output is relative to the Type of amplification use by the amp and the HP impedance. Interesting!

 

[ProtegeManiac]

So the power output is relative to the Type of amplification use by the amp and the HP impedance. Interesting!

Think of the amp topology like engine designs. A good SS or hybrid amp is basically like a German engine, like the old BMW 5.0L V8 - you can put it on a two seater without screwing up weight distribution or have to save the revs in the corners as much as an American V8 as on the Z8, you can put it in a midsize sedan and still have enough torque without being sluggish for grand touring overtakes as on the M5, small enough to relatively easily swap it into a small sedan like the Alpina 3-series with the same engine, and even its smaller, non-M variant does well enough on the X5.

 

[onevstheworld]

I am confuse about the comment that output power decreases as HP impedance increases. On the Schiit Magni 3 website it is stated like that but on the Little Dot MK IV specs it is the reverse. Less HP impedance less power.
There is something I do not get ?

Little Dot MK IV specs

Technical Specifications:

• SEPP (Singled-ended Push Pull) OTL in Class-A
• Frequency response: 10 hz~100 Khz (-1dB)
• THD+N: 0.1% (100 mW @ 300 ohm)
• Power Output:
• 500 mW @ 300/600 ohm
• 300 mW @ 120 ohm
• 100 mW @ 32 ohm
• Power Consumption: 30W (228V x 0.133A)
• Variable Gain: 3,4,5, or 10x
• Recommended Load Impedance: 32 ohm~600 ohm
• Input Impedance: 50K ohms
• Pre-Amplifier Output Impedance: 600 ohms
• Pre-Amplifier Gain: 3-10x (also controlled via gain switches)
• Pre-Amplifier Voltage: 10V RMS

What @ProtegeManiac said. I intentionally avoided mentioning OTL amps because those are tube amps and OP's isn't .

 

[Caribou679]

Well I am happy of what I learn in this thread. I'll be a little less ignorant.

@ProtegeManiac about the BMW when we talk of current delivery in ss amp, is this only a factor of loudness or is there more to it in regard of quality ,clarity, etc...

 

[ProtegeManiac]

@ProtegeManiac about the BMW when we talk of current delivery in ss amp, is this only a factor of loudness or is there more to it in regard of quality ,clarity, etc...

Without getting too deep into Ohm's Law and its engineering applications where it wouldn't be so straight cut - for example where most amps are voltage drive and OTLs have a lot of it, but have very weak current output and hence wattage output at low impedance - current performance has more to do with output at low impedance while voltage output has more to do with producing power or sustaining a higher output even as impedance rises.

In some cases for example if you take some amp specs side by side there are some can have much better current delivery and yet not that much better at voltage output. Compare the Asgard2 and Schiit Lyr2. At 16 or 32ohms they produce 1000mW and 6000mW; but at 300ohms, it's 300mW and 450mW. At low impedance the Lyr2 produces 600% the output of the Asgard2 but at high impedance it only has 50% more. That doesn't make the Lyr2 a bad amp though - it's just an example of how power delivery isn't always proportional to increases in impedance.