[Orpheus]

hi.

some of you might remember that i sent out my Grace 901 finding some small amount of hum while listening to Sony CD3000's. well, i just got off the phone with the tech there that's still evaluating my unit. well, he says it all was well within specs (actually 3-5db better than their benchmark.) but still, he ran a full load of tests, and even modded the transformer!!!--he said he removed it wrapped it in some "mu?" metal to block radiated low-frequency noise. and now he said it measures even 5db better than before!

anyway, i'm happy that though he didn't hear the problem, he still continued to work on the unit.

well, he said that after he gets off the phone with me, he would try with more phones, and let the unit burn in for 24 hours before sending it to me--i guess that's the procedure when they mod the power supply, for safety reasons.

...hmm, looks like i'm gonna be out a couple grand now, after i buy some of their mic preamps!

great company.

 

[Budrew]

I had an RCA jack come loose on the back of my 901, something I thought I could fix myself. But while trying to remove the cover I stripped one of the screws and was dead in the water. I emailed Grace and they said ship it in. No haggling over the DIY attempt or whatever. Quick turnaround, friendly people, and they even included a Grace baseball cap in the return box. Excellent! Still the best dang amp I've had too.

 

[Edwood]

Hoping that it all works when you get it.

Oh, yeah. I have to get back to Grace about their ground loop problem. Pulling the ground pin out of a power cord is not my idea of a long term solution. I'm being picky, I know, but for a product with a $1400 MSRP, I damn well better.

-Ed

 

[Orpheus]

ed...

don't be upset, but i just want to say: your problem is clearly caused by your own environment and is not caused by any deficiency of the Grace's design. at least, by the symptoms you have mentioned earlier, this is by far the most logical conclusion.

and i offer again to lend you my line isolation transformer. you should try that after you try rearranging your grounding scheme.

we know there's nothing wrong with your unit, since i remember it being hum-free, and performing supremely well at the last meet.

...though, during my conversation with the tech, he mentioned that the 901 is housed in an aluminum enclosure, which is good at rejecting high-frequency noise, but not so good at rejecting noise around the 60hz area. he said many other products are housed in steel cases, which would be better at rejecting radiating sources of hum-like noise.

so, perhaps you got it too near another source of radiation.

but again, i would suggest you to rearranging the grounding scheme, or taking me up on my offer to lend you the line isolator.
Quote:

Hoping that it all works when you get it.

yeah, i hope so too. but it seems more probable now that it's a problem of my environment, just like yours... since they found no problems. the tech ran all the tests, and as i have said, found that my unit also outperforms their average benchmarks. after the transformer mod (5db drop in noise floor), i should have the best performing 901 out there... if this doesn't do it, nothing will.

i should note though, even with the infinitely small amount of hum i heard, this unit still outperforms any amp i have heard. i'm looking for perfection. and no amp is closer to perfect than this one.

anyway, i believe in good service... and that's why i write all this. companies that offer outstanding service deserve more business.

(of course, that means that i also believe companies that have dang awful service deserve less business... and there's plenty of those too... unfortunately.)

 

[Music Fanatic]

Orpheus -- I am happy the Grace service department is (apparently) doing right by you. I'm looking forward to seeing your reviews when you get the unit back home.

 

[ServinginEcuador]

Wow, that is over the top good customer service. Sadly, far too many companies just do a quick listen, and upon finding nothing send it back as being "in specs." It's good to hear that these folks are going the extra mile to make it work for you, and that's encouraging.

Hey, we'll have to see how this one sounds when compared to Ed's. This June meet is starting to get too good to be true now! I can't wait.

 

[Edwood]

Quote:

Originally posted by Orpheus ed... don't be upset, but i just want to say: your problem is clearly caused by your own environment and is not caused by any deficiency of the Grace's design. at least, by the symptoms you have mentioned earlier, this is by far the most logical conclusion.

Don't get me wrong, I love my Grace 901. BUT I tested it vs. a Gilmore V1, which is also properly grounded, and it has almost zero problems compared to the Grace when it comes to ground loop buzz. Now either Kevin got something right where Grace did not, or my unit is defective. Yanking the ground pin on my power cord or simply throwing my hands up and saying I should go to a CD player or external DAC is nonsense.

I just think that such a well engineered (or so I thought) and built amp designed specifically to be used with computers and such should not have this problem. It just adds insult to injury when a DIY amp that costs 1/4 the price does not have this problem.

Are my expectations too high? I don't think so. Not at these prices.

BTW, it is the least noticeable in my environment, because I have the Grace on my PS Audio P300, my computer on a Brickwall Surge Suppressor. On another computer in an entirely different location(Iron_Dreamer's) the ground loop buzz was so loud it was unlistenable.

-Ed

 

[Iron_Dreamer]

Quote:

Originally posted by Edwood It just adds insult to injury when a DIY amp that costs 1/4 the price does not have this problem.

Well not really, the Gilmore V1/V2 sells for $500 new, so its' more like 1/3, if you consider a DACT V1 similar to what I have, it would have sold for more like $700, so now were talking about barely more than half.

At any rate, however, I agree with you that the Grace should not have such issues, especialy considering the circumstances you drew out.

 

[Edwood]

Quote:

Originally posted by Orpheus ...though, during my conversation with the tech, he mentioned that the 901 is housed in an aluminum enclosure, which is good at rejecting high-frequency noise, but not so good at rejecting noise around the 60hz area. he said many other products are housed in steel cases, which would be better at rejecting radiating sources of hum-like noise.

Hnmmmm. Perhaps lining the inside with a thin layer of copper sheet metal might help? Does anyone know where to buy copper foil? perferably adhesive backed?

Would copper be better than steel for shielding?

-Ed

 

[Music Fanatic]

Quote:

Originally posted by Edwood Yanking the ground pin on my power cord ... is nonsense.

Why? Your environment is feeding the Grace dirty power. I'm not sure why you don't have the same problem with your Gilmore -- I assume that the Gilmore either filters for this or does not have ground in the signal loop.

I don't think this it is fair to consider this a design problem ... but an environmental problem.

On the other hand, I can certainly understand how this could be very frustrating.

Anyway, please let us know what the Grace service department says when you call them up.

 

[ServinginEcuador]

Get a sheet of ERS and stick it in there instead of copper shielding. The stuff is supposed to work wonder with systems, so why not try a sheet for $20, $30 for adhesive backed sheets, and try it for yourself?

 

[Orpheus]

Quote:

Now either Kevin got something right where Grace did not, or my unit is defective.

your unit probably is not defective. ground loops are mysterious things. but the fact that your unit works fine in one environment, but does not in another only proves further it's the enviroment.

yes, there is something that's keeping Kevin's unit from humming while the Grace does. but that is not necessarily a fault of the Grace. it is merely a coincidence. do you know what i'm saying?

the way you can go about prroving that the Grace is bad is by trying it at other environments along with Kevin's amp. if the same situation is repeatable in 3 different locations, i'd have to agree with you. but otherwise, no, i seriously think there's nothing wrong with your unit.
Quote:

I just think that such a well engineered (or so I thought) and built amp designed specifically to be used with computers and such should not have this problem.

well, i guess... sorta. i mean, it's made to perform well, not necessarily just with computers. your computer isn't much different from any other type of audio device--a CD player for instance. so, i wouldn't say the Grace is made specifically for a computer, but for any audio device.

anyway, my Grace was hooked up to a Motu 896, which in turn was connected to my computer via firewire. i did not experience the same problem you had.

so, yes, it's possible yours is faulty, but HIGHLY unlikely based on your symptoms. i think that's what the tech would say too.

your symptoms are very indicative of ground loop problems, which plagues any audio component. there's where you should look first.

and AGAIN, i offer your my line isolation transformer. it should help.

 

[Orpheus]

you know, Ed, do me a favor and try this really fast:

get two RCA plugs and short the shield to the pin. then go ahead and plug those in, instead of what cables you got on there. disconnect the digital cables too, if you have them plugged in, leaving just the power chord in. now listen....

is there any hum?

 

[Edwood]

Yes, it's the sound card that's causing the ground loop. I have already confirmed this fact. If I yank the cables from the sound card (any sound card) the buzz dissappears. BUT the Gilmore V1 does not have the buzz. Curious. Does the Gilmore amp have something that specifically breaks ground loops?

I'll try the shorting plug trick later for the hell of it. I don't have any spare RCA plugs, so I'm just going to sacrifice a really cheap IC.

BTW, I am nit picking here. I am in no way saying that the Grace is crap. I wish I had the newer PS Audio xStream cable with removeable ground pin. I have to go with a crappy power cable in which I've yanked the pin. And I am not going to yank the pin on the xStream cable.

*edit* I found a cheap IC, I cut the RCA's off of it, I'll test it tomorrow. I packed up the Grace for a trip to Iron_Dreamer's place for another RME PAD mod session. This time we're going to make it have balanced analog output.

-Ed

 

[Edwood]

Quote:

Originally posted by Music Fanatic Why? Your environment is feeding the Grace dirty power. I'm not sure why you don't have the same problem with your Gilmore -- I assume that the Gilmore either filters for this or does not have ground in the signal loop. I don't think this it is fair to consider this a design problem ... but an environmental problem. On the other hand, I can certainly understand how this could be very frustrating. Anyway, please let us know what the Grace service department says when you call them up.

It's not the power. I have the Grace on the P300. If I disconnect it from the analog output of the RME PAD, no more ground loop. If I switch to the Grace's DAC, no more ground loop. The ground loop is coming from the sound card. I know every audiophile snob and their grandmother will simply say "Ha! Use a CDPlayer, sound cards are crap!" But not so fast! The Gilmore V1 did not have a ground loop in these identical setups.

So far, I would blame my environment too, except for the fact that I have not been able to duplicate the same ground loop in another amp. The Gilmore V1 I tested does have ground to earth ground in the signal loop (by testing continuity between ground pin of IEC and ground of the RCA jack, this is correct method?). Damn, Kevin. He's an evil genius. Must be some weird voodoo in there.......

I will test this again tomorrow. This time I will double check to make sure both are hooked up to the same outlet and conditioner.

-Ed