DIY amp advice for Grado SR-80 (with crossfeed)
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rhooper

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Hi Everyone,

I'm sure this question has been asked many times before... However I'm just not having much luck finding the answers I want by searching -- probably because there's just too much good advice on all matters hanging around!

I'm looking for a good DIY amp project for Grado SR-80 phones with a crossfeed circuit. Read on for more background.

I've recently acquired an iPod, which re-invigorated my enthusiasm for music. Somehow in the last 10 years, I stopped listening to music all the time. I used to listen to it pretty much non-stop.

I quickly noticed that the iPod headphones were uncomfortable and fatiguing to listen to. So I began my search for a replacement set. Like everything I do nowadays, I research on the net before I buy. I'm not happy to have low quality products unless I know what I'm getting into because i've had to comprimize due to cost.

After reading mixed reviews, I decided to get a set of Grado SR-80 headphones for home listening. Fortunately, they were one of the few good sounding phones I can find in town readily.

At first, listening to the SR-80s was more fatiguing than the iPod phones, however, after what is now about 40 hours of break in, they're sounding much nicer. I'm not yet "experienced" enough in audiphile terminology to describe the subtle changes that have happened during break in, but they are much more pleasing to listen to now than when first plugged in.

I started to notice that some recordings are disturbing when listened to on headphones due to the strong left/right seperation... So I started reading up on crossfeed filters, which I had previously heard mentioned when researching headphones.

This got me fiddling with WinAmp and Foobar, with no satisfactory (or even any results for that matter). I also fiddled with the headphone setting of the Audigy 2 ZS Creative drivers. I didn't like the flat sound. I've been listening on my PC using 2.1 speaker mode, or using my iPod. In the end, I uninstalled the Creative drivers, intalled the xk project drivers, got the crossfeed rigged up in the DSP and had a listen. Even if the setting wasn't optimal, I could feel a huge difference while listening to tracks that had too much left/right seperation. The recordings no longer sounded unnatural and jarring.

Unfortunately, I can't keep the kx driver installed, as it breaks the 3d sound in games, which I also play a few of. So I have the Creative driver back installed, and need a new way to get crossfeed filtering.

I could just build a crossfeed filter, but frankly, I suspect the Audigy 2 (and to a lesser extent, the iPod) do not have strong enough amps to drive the Grado phones optimally. The biggest hint about the Audigy 2 amp being weak is the fact that listening at the same volume to the same recordings on the PC is more fatiguing than the iPod. If the Audigy amp is weak, I can't imagine that the iPod is that much better.

So -- I'm competent with a soldering iron and schematics, so I'm looking to make myself a (not necessarily portable) headphone amp with a crossfeed filter in it. I'm not looking to go broke, however, building my first amp. I'd like something that has as little noise as possible (as neither the iPod and Audigy 2 has any audible hiss at any volume setting on the Grado phones)...

Cheers and thanks in advance.
Roy
 
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shimage

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Quote:

Originally Posted by rhooper
This got me fiddling with WinAmp and Foobar, with no satisfactory (or even any results for that matter).


For clarification, does that mean that you tried the crossfeed filters and they sucked, or you just couldn't find them? I'll admit that I prefer the Meier crossfeed, but the foobar plugin generally gets the job done for me.

I don't know if you've seen this yet, but it sounds sort of like what you're looking for. Tangent's website is an excellent place to start. Beyond that, I don't really have the experience to suggest much of anything, though it seems that most people suggest you start with a cmoy or mint, if you haven't done DIY audio before. Personally, though, I don't think pimetas are really that much harder to put together (and I have a severe aversion to SMDs, which makes the pimeta more appealing than a mint). As a side note, shouldn't this be in the DIY forum?

If you're feeling a bit more ambitious, there's always Jan Meier's crossfeed and amplifier projects, but I don't believe that he sells PCBs, so you'd have to etch your own.
 
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rhooper

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You're right: I should have been in the DIY forum. I just didn't notice it down there! Bad me.

I tried the crossfeed filters and didn't hear any change whatsoever with Foobar and the Winamp one caused the audio stream to be corrupted when enabled.

Yeah, I've seen the CMoy and Jan Meier models -- but i'll have to look at the mint and pimeta.

Cheers, off to the right forum now.
 
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n_maher

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My advice, would be to take a look at the Millett-Hybrid amp
. It has wonderful synergy with the Grado line and is a pretty simple DIY project.

Nate
 
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rhooper

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After spending a fair bit of time reading, I'm torn between building a CMoy/CMoy variant or a PIMETA.

I'm also having indecision about which OP Amp to use. I'm tempted to grab several at the same time and roll them.

Realistically, I think I'll likely start by building a CMoy with a OPA132/OPA227 and then build a PIMETA. I suspect that the AD8065 is not well suited to Grado SR-80s.
 
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samlasker

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Roy,

We've got similar requirements - so, I thought it might be useful if I posted some of my findings. However, I suspect that you've probably read much (or all) of the original sources yourself. A few differences between your requirements and mine: (1) I'm ultimately shooting for a portable design, (2) croosfeed is not so important to me. (I don't find it fatiguing to listen to contemporary pop/rock/alternative/classical without crossfeed. Beatles-"stereo", on the other hand, is pretty much unbearable on headphones for me, regardless of crossfeed; for this reason, I usually convert these tracks to mono.)

Also, I hope that the experts here will point out any errors in what I'm saying.

Quote:

Originally Posted by rhooper
After spending a fair bit of time reading, I'm torn between building a CMoy/CMoy variant or a PIMETA.


I recommend a 3-channel design like the PIMETA. Why? Well, Xin says so.
I've decided on a Morsel 3-channel, which is basically a PIMETA sans buffers. I might add buffers later to see what difference they make.

Quote:

Originally Posted by rhooper
I'm also having indecision about which OP Amp to use. I'm tempted to grab several at the same time and roll them.


I've narrowed it down to AD8610's and AD843's since they have very good sound and, important for Grados, can provide a lot of output current. The 8610's are SMD's, however. I don't mind that since I wanted some surface mount practice anyway. One can also get premounted ones from brndog.com or amb's shop - probably, there are other sources as well. Since I'm on a budget, I get my chips as free samples.

Quote:

Realistically, I think I'll likely start by building a CMoy with a OPA132/OPA227 and then build a PIMETA.


I say "Screw realism!" though I should probably add "Whatever you do, don't listen to me!"



EDIT: Regarding crossfeed in foobar2000: I'm surprised that it doesn't work for you. Have you tried getting the plugin directly from the source? The plugin should be very noticable with Beatles-"stereo". Also, the winamp plugin works with foo via "winamp dsp plugin".
 
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rhooper

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Quote:

Originally Posted by samlasker
A few differences between your requirements and mine: (1) I'm ultimately shooting for a portable design, (2) croosfeed is not so important to me


I've placed the order for the parts for my first amp. I can't wait for them to arrive. I expect it will be relocated to work at some point and that I'll build myself a second amp shortly afterwards. I have a feeling it'll be a PIMETA. I decided that in order to keep costs moderate and complexity down, I'd start with the CMoy with a modified Linkwitz Filter.

The build is going to be fairly modular, with the CMoy and crossfeed built on seperate boards. The idea is that i'll be able to swap in a different amp and convert the Cmoy into a pocket amp.
Quote:

Originally Posted by samlasker
Also, I hope that the experts here will point out any errors in what I'm saying.


Me too!
Quote:

Originally Posted by samlasker
I recommend a 3-channel design like the PIMETA. Why? Well, Xin says so.
I've decided on a Morsel 3-channel, which is basically a PIMETA sans buffers. I might add buffers later to see what difference they make.



I will eventually build a PIMETA or Morsel. I consider the CMoy my first amp
It'll be fun to hear the difference. Maybe i'll build both so I can hear the difference between a CMoy, Morsel and PIMETA. I was sorely tempted to build one of the many other amp variants I saw posted... 3 channel definitely was on the short list, but... This is a new obsession, I suspect.
Quote:

Originally Posted by samlasker
I've narrowed it down to AD8610's and AD843's since they have very good sound and, important for Grados, can provide a lot of output current. The 8610's are SMT, however.


Based primarily on Tangent's Notes on Audio Op-Amps , I picked the OPA132 and OPA227 to try out to start with, primarily due to cost. The statement about the AD823 sounding agressive put me off trying Analog Devices Op-Amps it as my first Op-Amp. I'll have to get some samples to try many different Op-Amps out. The laid back description that applies to the Burr-Brown amps seems to make more sense with the Grado phones -- but i'll let you know if I'm wrong!

Cheers!
 
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samlasker

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You are of course right re pairing bright headphones with more or less aggressive opamps. There is, however, at least one reason why I would like a snappy sound: radiohead.
Also, the AD843 is supposedly smooth as per tangent's site. But of course, your own listening tests are what matters.

On a side note, the OPA627 isn't available for (straight-forward) sample requests anymore!
 
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