Thanks, yeah the tube hybrid has a 6 ohm output impedance published specification (the solid state is less than .1 ohm), which is probably still way too low to have any affect on the HD800's frequency response.
When I tried to compare the tube hybrid amp to the solid state with the Mr speakers aeon (14 ohm flat impedance curve) I couldn't hear any difference either, despite the 6 ohm Zo of the tube hybrid being well inside the 1:8 Zo to hp impedance rule.
The only thing noteable, is that the amps weren't level matched with Aeon unless I readjusted from the hd800 volume settings. The tube hybrid was producing more voltage with the Aeon compared to the hd800 and had to be turned down.
With both amps calibrated to produce 1.033 volts on a 50 hz sine wave with hd800, the tube hybrid produced 1.135 volts and the solid state 1.012 volts with the Aeon connected at the same volume positions. The tube hybrid had to be turned down a bit with the Aeon as it was noticeably louder otherwise. Once I did that I couldn't discern an obvious difference in sound.
if the load has flat impedance, then you're much less likely to get FR change(unless the amp has protective caps at the output or some weirdo design). you'd need a really massive impedance ratio difference for the damping itself to be audibly different on most headphones, so yeah a headphone with flat impedance is more likely to sound the same on a lot of amps.
about the HD800, for the impedance change to make an audible variation, you'll need really good listening skill, or relatively significant impedance on one of the amps. with nothing getting below 300ohm, most amps won't create much change in frequency response(at least not typical SS amp trying to be flat). but when doing the Big Sound challenge on Innerfidelity, a few people were able to recognize some of the amps with a hd800. while they would tend to fail with some of the other headphones with flat impedance like most planars.
of course if you were to test some multidriver IEMs the same way, which often have impedance as low as the Aeon but as variable as the hd800, going from 1ohm to a 6ohm amp would almost never go unnoticed, just thanks to the frequency response change.
as a rule of thumb, when you stick to the 1/8 damping ratio even with non flat loads(as long as the lower impedance value of the headphone is still good for the 1/8 ratio), you can expect that the FR variations will stay below 1dB. so while possibly audible, FR alone shouldn't be much of a concern.
*edit to put back all the letters my laptop's keyboard had eaten.
As a rule of thumb, when you stick to the 1/8 damping ratio even with non flat loads(as long as the lower impedance value of the headphone is still good for the 1/8 ratio), you can expect that the FR variations will stay below 1dB. so while possibly audible, FR alone shouldn't be much of a concern.
.5 dB variation in frequency response is completely inaudible when you're playing music. Overkill. If you can keep variations under 1 dB you can move on to worry about something else.
.5 dB variation in frequency response is completely inaudible when you're playing music. Overkill. If you can keep variations under 1 dB you can move on to worry about something else.
Below 1 dB, it doesn't matter at all. You're safe for the purposes of listening to music. Maybe not tones, but I don't listen to tones if I don't have to.
Below 1 dB, it doesn't matter at all. You're safe for the purposes of listening to music. Maybe not tones, but I don't listen to tones if I don't have to.
Audibility of any response change depends strongly on bandwidth (Q).
For example, if you change 1dB but the area of change covers 200Hz to 5000Hz (Q= approx 0.2) that will likely be an audible change for anyone. Adjust Q up to 10000, and now you can suck out 40dB and nobody can hear it unless one note lands exactly on it because that change affects a tiny sliver of an octave.
It ain't just how many dBs, it's how many Hz too. If you just talk dBs you've missed half the story.
No, most of them involved tones. It's easier to detect differences in constant tones than dynamically changing music. The dB scale was designed for each unit to be a JDD measure. If you get below a dB, you are doing fine. No need to worry or quibble. You have a damn fine sounding system if you can get within a dB of flat throughout the frequency range.
0.5 dB or less puts you on the safe side so that's why I use it as the target criteria for output impedance (there is also damping and linear distortion criteria, but they are often less demanding).
I was only giving the practical margin ensured by that 1/10 impedance ratio "rule"(protective caps playing high pass filters not included in the max 1dB variation estimate).
also the rule usually goes suggesting to get "at least 1/10".
1dB is the limit of spl differences I can hear on a 1khz test tone. Probably more like 3db on music, but I haven't tested that. About .05 volts of variance seems to be where volume differences in music are apparent when I'm level matching with my multimeter. I haven't used an spl meter to try and see what that equates to in dB.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
