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published: Oct-29-2017

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NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons flat’ sharp peaks and ‘wiggles’. I do not use smoothing because some info about sound quality is lost when plots are smoothed.

Aside from a small correction of the microphone itself also some correction in the lowest frequencies is applied to the plots to compensate for the perceived loss of bass when using headphones. This is described HERE in more detail.
A ‘horizontal‘ frequency response curve on the shown frequency response plots on this website thus indicates a perceived ‘flat’ tonal signature.

ALL measurements are made with a good SEAL on a flatbed measurement rig.
The shape of your head, bone structure, pad size, pad ‘softness,  (compliance), hair or no hair and or wearing glasses may (drastically) change the frequency response of some headphones, so… your personal experience may differ substantially from these plots.

Frequency response (tonal balance) is the most sound-determining aspect of headphones. A horizontal line shows audible neutral response in the plots on this website. Deviations in different severities at different frequency bands have an effect on the sound character.
The bigger the deviation the stronger the effect.

Below an aid to help determining the sound character of headphones with relation to the frequency response.


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Grado SR125i

The Grado SR125i is one of the many Grados in a line up. All of them are highly related to each other and appear to have similar drivers.
They have quite a following cult. These are a love-or-hate headphones.
The biggest differences between the cheaper versions, SR60, SR80, SR125, SR225, SR325 seems to be in the pads and perhaps in better driver matching. The SR125 has been replaced by the SR125i (measured here) and lately by the SR125e versions. Differences between the various suffixes seem small, certainly not as big as some reviewers would like you to believe.
The e versions have a slightly higher efficiency.
These are low impedance headphones (32 Ω) and are suited to be driven directly from portable gear.
The 6.3mm plug on this SR125i won’t fit and you would need a 3.5 mm to 6.3 adapter cord. I wouldn’t use a 3.5mm to 6.3mm adapter because the weight of the cable and plug will ruin the 3.5mm socket.
The newer versions do have a 3.5mm plug and a 6.3mm adapter and have less thick and stiff cables.
That cable is very thick, heavy and stiff. Fortunately it isn’t very microphonic and dual entry. Comfort and modern looks aren’t great… I would even say poor compared to most other headphones. Clamping force is low.
These headphones can only swivel in one axis and may be a poor fit to some because of it.

First up is the measurements. Frequency response is shown below (Left, Right):

SR125 freq response
O.K…. do they really sound like this ?  Yes… they do, unfortunately. I know there is quite a following cult highly praising the Grado sound.
I can go along with this a bit with the PS series and the early Grados but not these ones.The driver matching isn’t that great but it isn’t audible to me. What is audible is the steep bass roll-off. Very similar to the AKG K400/K500 series. Bass doesn’t appear to be really ‘lacking’ but it sounds ‘thin’ and without any ‘body’. Very obvious on direct comparisons.
These headphones DO sound very ‘forward/open’ and appear to sound highly detailed and have good ‘clarity’. The forward/clear sound is partly to blame on the substantial 2kHz peak and raised treble. Also the seemingly hyper-detailed sound finds its origin in the elevated treble. The sharp peak(s) and combfilter effect usually indicate ‘rough’ or ‘grainy’ treble, where as much less peaky and not elevated treble usually indicates ‘smooth’ treble. While sometimes these kites won’t fly they do in this case.
The SR125i treble sounds a bit ‘coarse’ and ‘sharp’. Sibilant on some music and ‘piercing’. Together with the lack of ‘body’ and the flat upper-bass to mids it sounds anemic and thin.  Not particularly bad sounding as it also has some decent qualities to it but it lacks in certain areas that, to me, matter.

Below the CSD (a.k.a. waterfall plot) where Left and Right are superimposed:

csd sr125

It appears as that the 2kHz peak is a resonance. The peak around 4-5kHz and 9-10k as well. The CSD looks a bit messy when comparing it with most other (better sounding) headphones. That 2kHz resonance may have something to do with the Grado lacking real detail as well and the accentuation of ‘sharp details’.
The FR can be changed with other pads and Stratocaster has shown the drivers themselves are capable of producing better sound.

The Grado can also be connected to a high output R amplifier (120Ω in this case) but this will ‘cost’ about 11dB in SPL. You gain a little lift in the bass area by max 2dB, and the upper treble by +1dB. A slightly bassier sound is the result.
Below the plots of the SR125i when driven from a near amplifier and a 120Ω amplifier (right channel only).

SR125 120 ohm

Having owned an SR60 for a while, and loving certain aspects but hating others, and having measured and heard this headphone I will gladly stay away from the ‘standard’ Grado line up. Perhaps with the exception of the PS series and ‘original’ Grados.

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