Hello my fellow Head-Fi friends,
 
I sent in my Grado SR325i's to Grado Labs in New York about a month ago. The cord had lost contact in the left side of my headphones and I believe there was also an odd rattling noise that had began to plague my headphones (Grado Grattle?). From what I've researched, this can occur when the transducer becomes creased or folded. Anyhow, I noted both of these issues in the area provided on the repair request form. They managed to repair them in just over a week to my surprise and I was elated to have them back in my possession. That was until I gave them a listen. The bass seemed to be severely diminished and the highs notably more bright. Allow me to assure you, I am NOT a bass-head. I enjoy a healthy dose of EDM, but by no means to I saturate my ears with excessive amounts of low-frequency. Still, I could clearly tell that something was much, much different than it used to be in regards to the sound signature. Before the repair, they sounded like gold. No complaints. The bass what clear, even, and present. Mids and highs were balanced (it was ever so slightly bright, but not enough to notice during non-critical listening). What happened?!
 
Being the type of person I am, I'm never quick to conclude only one possibility when a problem arises. In this case, I came up with several possible causes for this (at least I think one of them might be the cause). I will list what I've come up with below. My hope though is that someone with more experience or insight than me can pinpoint what the issue is.
 
- Does Grado replace parts without informing the customer? One of my thoughts was that they may have replaced something in the can itself. Would that effectively make it "new" in the sense that I'd have to go through the process of burn in again?
 
- I'm also running a new setup. I recently purchased the refurbished Arrow G3 Amp from Headstage. I received it about two weeks after I got my headphones back. I really thought that it would improve my headphones but they still lack the sound they used to have before the repair. Does that say more about my headphones of the amp itself? *Note: I am running this through a 160GB iPod classic using the Fiio L9 as the LOD.
 
- I did have a new pair of L-cushions put on my Grados as part of the repair. I'm pretty sure those are still breaking in. Could that have something to do with the sound? I know that the cushions can have a large impact on the sound (I also have the larger "doughnut" cushions that go on the GS-1000's I think).
 
- I use the mini-adapter cable from Grado. I can tell it's getting old because the sound occasionally cuts out if I'm not careful about the position of the wire.
 
 
Welp. That's all I've got folks.Thanks for listening to me whine, lol. Seriously though, any explanations or suggestions would be greatly appreciated. Thanks guys!

I would guess that since you had reported a rattle, they may have found a defective driver and had to replace it. If so, they would have likely replaced both drivers in order for the sound to be consistent ear to ear. If this was the case, then yes, your headphones would effectively be "new" again and would require a period of time to burn in.
 
However, you also mentioned that you had replaced your setup... that too could certainly account for a change in sound.
 
I'm not sure if the L-cushions change over time enough to account for a significant difference, others may know.

So it sounds like maybe I wasn't too far off. I guess it's burn-in all over again.

Pretty much everything you mentioned could contribute. They probably replaced the drivers, which will have an effect. They definitely replaced the earpads, which will have an effect. You also have a new setup, which will have an effect. Additionally, your time away from them could contribute, especially if you're been using something with a heavier sound signature in the meantime. It's hard to isolate a single cause, but I believe you'll come back around to them after a week or two of listening.

Good news . . . I emailed Grado Labs and they replied back (in record time I might add (ten minutes)). Here is what they said:
 

"Hi Sean
 
both drivers were replaced.
 
it will take some time for the new drivers to relax.
 
please do not run them in over a long period of time, use them normally and the drivers will eventually relax.
 
running them in on a continuous basis will damgage the drivers"
 

 
What makes me curious is that they said specifically, not to run the over a long period of time and that a continuous basis will damage the drivers. I hear a lot about "burn in" for new headphones but never which method is best. By that I mean the two most common methods: Normal listening and artificial (e.i. Pink Noise files or an extended playlist for several or more hours). Makes me wonder if anyone should ever try any method aside from normal listening.

in limbo said:

  Good news . . . I emailed Grado Labs and they replied back (in record time I might add (ten minutes)). Here is what they said:
 

"Hi Sean
 
both drivers were replaced.
 
it will take some time for the new drivers to relax.
 
please do not run them in over a long period of time, use them normally and the drivers will eventually relax.
 
running them in on a continuous basis will damgage the drivers"
 

 
What makes me curious is that they said specifically, not to run the over a long period of time and that a continuous basis will damage the drivers. I hear a lot about "burn in" for new headphones but never which method is best. By that I mean the two most common methods: Normal listening and artificial (e.i. Pink Noise files or an extended playlist for several or more hours). Makes me wonder if anyone should ever try any method aside from normal listening.

Click to expand...

This is consistent with what Grado have recommended historically. The quote I have is:
 
"As any mechanical device, the headphones will improve in performance with use. We firmly recommend not allowing the headphones to play continuously for extended periods of time. We strongly suggest letting the headphones break in naturally with normal use."
 
...since that is what they recommend, that is what I have always done...