[Edwood]

Quote:

Originally posted by Orpheus hey ed, can you open your unit really fast and describe to me the chips attached to the heatsink? there should be 2 small ones and one huge chip. are the two small ones different from each other? thanks.

I'm out and about, but I'll crack that puppy open when I get back home this afternoon. And yeah, I'm taking pics too.

This ground loop thing is pissing me off. How is it that a professional amp that is more likely to be used with computer audio is prone to these ground loops and other consumer amps are not?

I'm going to get to the bottom of this....


-Ed

 

[Wodgy]

Orpheus, the two things attached to the heatsink towards the back of the unit are the power regulators. The positive and negative regulators are different and so may look different. There is only one op-amp (and no buffers); it's the thing attached to the heatsink closest to the front of the unit.

 

[Born2bwire]

Quote:

Originally posted by Edwood How is it that a professional amp that is more likely to be used with computer audio is prone to these ground loops and other consumer amps are not?

Well I wouldn't say that. How many people are going to use a $1,400 amplifier on a computer instead of a $1000+ CD player? Out of curiosity, can you plug your amp into a different outlet or better yet a different circuit than the computer?

 

[ooheadsoo]

Ed's trying to say that computers are common recording engineering tools, and the grace is a pro amp designed to be used in the recording room.

 

[Orpheus]

Quote:

Orpheus, the two things attached to the heatsink towards the back of the unit are the power regulators. The positive and negative regulators are different and so may look different. There is only one op-amp (and no buffers); it's the thing attached to the heatsink closest to the front of the unit.

oh okay, thanks wodgy for the clarification! okay... cool, i'm calmer now.

 

[Edwood]

Quote:

Originally posted by ooheadsoo Ed's trying to say that computers are common recording engineering tools, and the grace is a pro amp designed to be used in the recording room.

Exactly.

I'm not going to beat the dead horse of the whole sound card vs CDP here.

I am discussing about the ground loop issue with the Grace 901.

We'll see if the "cheater plug" works.

-Ed

 

[strohmie]

Hey Orpheus, just curious about something -- which amplifiers have you tried that do satisfy your noise floor needs? I recall with the "fixed" v0.3 Perreaux there was still a low hum that you could hear.

 

[Music Fanatic]

Quote:

Originally posted by Edwood Exactly. I'm not going to beat the dead horse of the whole sound card vs CDP here. I am discussing about the ground loop issue with the Grace 901. We'll see if the "cheater plug" works.

But it sounds as if it is the computer that is improperly grounded from your description.

Anyway, keep us posted on what happens.

Edit: I think I may have found the source of your problems. There is a hampster wearing R10's bouncing on top of your Grace 901. The Grace is not designed for this.

 

[Edwood]

Well, it's a ground loop for sure.

I took pliers to a cheap pair of power cables.

No more hideous ground loop.

Too bad I have the older PS Audio Xstream cable. The new ones have a removeable ground pin.

Now here's my question.

How is it that a $500 amp has no ground loop, but an amp that costs more than twice as much have ground loop problems?

Granted, practically speaking, it's at too high a level for me to hear it with my setup.

I'm just being a picky person.

-Ed

 

[Edwood]

Quote:

Originally posted by Music Fanatic Edit: I think I may have found the source of your problems. There is a hampster wearing R10's bouncing on top of your Grace 901. The Grace is not designed for this.

Yeah, I took em away from him. They're on my head now playing sweet sweet music.........

-Ed

 

[Music Fanatic]

Quote:

Originally posted by Edwood How is it that a $500 amp has no ground loop, but an amp that costs more than twice as much have ground loop problems?

Maybe ground isn't properly connected on the cheaper amp.

 

[Edwood]

You may be right, I'll check it's continuity with the ohm meter.....

-Ed

 

[Wodgy]

Some amps have a ground loop "breaker" (usually a resistor in parallel with a capacitor) to filter out 60hz currents and reduce the likelihood of ground loops. Jan Meier describes how he implements this in his own amps here:
http://home.t-online.de/home/meier-audio/headamp.htm
Some amps don't. My guess is that Grace depended on the powerline filter in the Schaffner IEC assembly they use. It probably wasn't enough for Ed's computer. Computers have extraordinarily dirty grounds, for obvious reasons (millions of switching transistors).

 

[Orpheus]

Quote:

Hey Orpheus, just curious about something -- which amplifiers have you tried that do satisfy your noise floor needs? I recall with the "fixed" v0.3 Perreaux there was still a low hum that you could hear.

heh he.... you have a good memory. i've bought 2 different ppa's, 1 super-modded sugden headmaster (which arrived DOA.... great....... 3 months for my insurance payment, and the seller seems to be ignoring me right now), and now my grace ($3000 later.... heh he)

but the 901 should be good after Grace fixes it. should be the end of my quest hopefully.

 

[Edwood]

Yep, you're right. The cheaper amp is not grounded to Earth ground.

The Grace is. Continuity goes beeeeeeeeeeeeeeeeeeeep!

-Ed