[gihe]

Sorry about the cryptic title - it's just that I've been a long-time SR-80 user and have recently acquired some brand new SR-225i's. From all accounts, these cans are supposed to be pretty bright but, on first listen, there's a huge difference between them and the 80's.
The 80's are a heck of a lot brighter and more forward in presentation.
Sure, there's more bass and warmth and depth in the 225's but the treble seems to lack something. Could it be that I'm just used to the 80's and have adapted to too much treble over the years?
I'm looking to achieve a neutral sound with my setup; as little coloration as possible (given my pathetic budget). The phones are going straight into a Mission Cyrus 1 amp.
 

 

[NA Blur]

You should hear more treble with the 225 solely based on the bowl pads.  The 80's and 225's are actually virtually the same excluding a more precise driver match ( db ) for left and right as well as the 225 having the bowl pads.
You can see here on the Gradolabs site that there is only a 2kHz extension on the 225 over the 80.  The 80's go from 20Hz - 20kHz and the 225's go from 20Hz -22kHz.  This makes the 225 brighter than the 80's and the comfy pads on the 80's filter the driver more so you should hear less treble and bass.
http://www.gradolabs.com/page_headphones.php?item=ec27f1750be96023333af0dfe546af44
 
Here are the FR curves for both the 80 and 225 overlapped.  See how there is really no discernable different in the curves?  I did the same thing you did and went from the 80 to 225 and ended up selling both for a pair of RS-1i's.  After discovering the severe discomfort I sold them as well and am frankly done with Grado headphones.  I only recommend the SR-80i now.
=353&graphID[]=373]http://graphs.headphone.com/graphCompare.php?graphType=0&graphID[]=353&graphID[]=373
 
 
The only major improvement I ever heard going from the 80 up, besides the treble on the 225, occured at the 325 level where the bass goes down a bit deeper.  The RS-1i's sound awesome, but are terribly uncomfortable.
 
Hope that helps.

 

[gihe]

Thanks for the reply. My SR80's have bowl pads - and have always had bowl pads - so I don't think that's the cause.
These new 225i's are simply less bright than the 80's.  I think the extreme top end is there but I estimate a drop in the 5kHz-8kHz range which, together with the heavier bass, makes the whole sound a lot darker.
Either it's me or the cans. I'm not saying I dislike the sound - but I do want the reassurance that my cans are factory standard. Is there any way you can send Grado phones off to be tested?

 

[Argo Duck]

NA Blur's overlap of the FR curves is really helpful here. It would seem both should sound pretty similar - in fact, indistinguishable if FR is all there is to sound signature. However, there is supposed to be a gain in quality as one goes up the Grado range. If one makes the minimal assumption the only difference is quality control, then one might suspect your SR80 is at fault. Specifically, elevated in the 5-8kHz range you mention.
 
Maybe you should contact Grado? Or search the threads here a bit more. Unfortunately, I have only the RS1 and SR60 to compare. The RS1 is darker (or less brash), and much more controlled and neutral, but you'd expect it to be!
 
Small point but I'm not sure a 2KHz extension to 22KHz would make a perceptible difference in brightness to most people. We're not particularly sensitive up there, especially those of us past our 20s <ahem>! 
 
 

 

[gihe]

Yes, I have considered that the original SR-80's were maybe a tad too bright. The 225's certainly have a smoother top end.
 
However, I think I'm onto something that may be the cause....
 
The pads are subtly different. About a year ago, I replaced the bowl pads on the 80's with some fresh bowls ordered from a Grado supplier. I've just taken a look at the new 225i pads and there's definitely a difference in the construction.
 
The pic below shows the new 225i pad on the left and, on the right, the replacement pad I've been using on the 80's. Not a great pic but the 80 pad is clearly about 2mm thicker. 

 
 
The second pic shows the 80's replacement pad (right) to have firmer, straighter walls and a firmer and wider "shoulder" before the inward slope - a bit like a car tyre once it's been filled with air. These pads also have a stiffer back. The 225i pad (left) feels softer with slightly less dense foam, so one could see how the pad on the right could hold one's ears a few mm further away from the driver.

 
I've experimented by swapping the pads between the cans. The 80's replacement pads on the 225i reveal more treble and slightly less bass, while the stock 225i pads on the 80's give a better bass and ever-so-slightly decreased treble. With the pads swapped, there even less difference now between the two phones (the 225i just edging with a sweeter midrange and soundstage)
 
Has anyone come across these pad designs before and could 2mm really make this much of a difference??

 

[Argo Duck]

I haven't experimented with different pads but there's certainly information here and there (e.g. one of the RS1 owners threads; the LCD2 thread) that highlights that subtle positional changes in the phones on (RS1) or over (LCD2) the ears make quite detectable changes in sound.