[Edwood]

Quote:

Originally posted by 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?

Stillpoints ERS Paper? Oh man this looks like snake oil. I guess it's not too expensive to to experiment with. Luckily the Grace 901 is small. 1 sheet may suffice.

Is there a cheaper place to order from than http://www.cryotweaks.com/Ers.shtml ?

-Ed

 

[Hirsch]

Quote:

Originally posted by Edwood 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.

The Headroom Max comes with a switch for floating the ground. When I auditioned one, the only way to keep it quiet was to keep the ground floated. I did not consider this to be a problem. Ground loops happen.

Note that lifting the ground does not unground the unit. It's still going to be grounded through the neutral side of the AC, and through your interconnects to the ground on your source. The only real disadvantage of a floating ground is when a major short develops in your unit, it may not set off the circuit breaker on the AC line if it doesn't go directly to ground.

 

[Orpheus]

you know, if you use the balanced ins on the grace you probably won't have this problem. on balanced cables, the shield is not part of the signal path.

 

[ServinginEcuador]

That's the normal price, and the only price, for the ERS. It has received universal accalim so far, and AC1 announced a new innovation for his power cords he had built that is nothing more than a small amount of this stuff installed on one end. It really works.

 

[Wodgy]

You won't solve ground loop problems by adding shielding, no matter how fancy the shielding. Don't waste your money on this. Shielding is completely unrelated to how ground loops form.

Just use a cheater plug. Your entire system should only have one earth ground. If you have multiple paths to earth ground your system is not set up properly. Fancy power supply tricks can help with this, but they're just workarounds to compensate for you not having a correctly set up system. Even though you don't hear the hum with the Gilmore, you will likely improve the performance of the Gilmore by adopting a proper grounding scheme (the noise level will probably drop from -120dB to -126dB or something similar) -- even more inaudible, but something to strive for anyway.

 

[Orpheus]

Quote:

You won't solve ground loop problems by adding shielding, no matter how fancy the shielding.

yeah, actually wodgy's right.... see, you said that you have your amp in the same place, but simply disconnecting the interconnects solved the problem right? so, it's not a matter of shielding from any radiation, since you don't move your unit... it's clearly a ground loop problem. so, do the cheater thing like wodgy says, or you can use my line isolator. if you can get away with the cheater plug, that'll be better, cause transformers always color the sound to some degree (though maybe not audible.)

 

[Edwood]

Quote:

Originally posted by Orpheus you know, if you use the balanced ins on the grace you probably won't have this problem. on balanced cables, the shield is not part of the signal path.

You are absolutely right.

I now have my RME PAD with the analog output stage bypassed and now with balanced outputs. The ground loop is gone! There is a weird noise (very slight) if I turn the high gain on. But I would never want to listen at those volumes with my R10's. At standard gain. No buzz.

Guess there is no need for $30 paper inside the Grace.

Thanks again for the help, guys.
Special thanks goes to Iron_Dreamer for having the cahones' to start ripping things off of his sound card.

-Ed

 

[Edwood]

Quote:

Originally posted by Hirsch The only real disadvantage of a floating ground is when a major short develops in your unit, it may not set off the circuit breaker on the AC line if it doesn't go directly to ground.

Ah yes, that's right. Then the fuse won't be able to do it's job then. So no listening to headphones in the bath then, right?

-Ed

 

[Iron_Dreamer]

Quote:

Originally posted by Edwood [B Thanks again for the help, guys. Special thanks goes to Iron_Dreamer for having the cahones' to start ripping things off of his sound card. [/B]

You're welcome, after all life would be quite a bore to me without a little risky business every now and then

 

[Orpheus]

Quote:

Note that lifting the ground does not unground the unit. It's still going to be grounded through the neutral side of the AC, and through your interconnects to the ground on your source. The only real disadvantage of a floating ground is when a major short develops in your unit, it may not set off the circuit breaker on the AC line if it doesn't go directly to ground.

hirsch, can you explain a little further? i was under the impression that there could be risk of shock if the ground is lifted. this isn't true? then why don't we lift the ground on everything, save one designed unit?--then that would assure the quietest configuration. i just don't do that cause i didn't want to be shocked... but if you're saying there's no danger of that... well... what you think?

 

[Orpheus]

oh my gosh, the unit's so perfect now!!!

all problems are GONE. the unit is absolutely silent to my ears, even with the Sony CD3000's. the tech tested it with Grado's before it left, and said it was silent with those phones too. MAGNIFICENT. i'm happy now!... looks like this week's gonna be good for me.

...man, i've just had some terrible luck lately..... it's looking better now. heh he.

the only problem at all with this unit is that the feet aren't 100% level. but oh well. i don't care too much as long as the performance is perfect. and now it is.

incidentally, i did open it to see what they did... but sorry, i still dunno cause they wrapped the whole damn transformer in electrical tape! but they probably just wrapped it in some kind of metal underneath.

anyway.... going to lunch. then i'll be back for my baby.

 

[Orpheus]

by the way, here's the letter the tech returned with the unit:

"Hi Dean- As discussed initially your amplifier was run through a comprehensive bench and listneing test. All noise specs (both boradband and 60Hz induced) were within spec. Additionally common nmode rejection on both channels was great. On the listening bench, broadband noise was at the common low level and 60Hz hum was undetected. We wrapped your transformer in a special mu-metal band in order to further isolate the radiated energy. This provided a measurable decrease in induced noise. Broadband noise was reduced to -88.5dBu unweighted and -94dBu A-Weighted. Listening once again revealed no induced hum or extraneous noise on the audio outputs. It was tested under many different loads and positions. After our conversation the tests were repeated using a 32ohm load. The results did not change. Your unit was given a complete burn-in cucle, bench and listening test. Everything is great! Enjoy. Please let us know if we can be of any further assistance. -jamie"

so, if this isn't "going out of your way" to help a customer, i don't know what is.

 

[gpalmer]

Hmmm, I might have to take them up on that myself. There is a slight bit of hum in high gain mode that is more than i care for...

 

[Orpheus]

heh he..... if all of a sudden they get 100 calls for hum problems in the 901, i'm gonna go hide under the desk...

but i want to make VERY CLEAR:

for those concerned about hum in the 901, we're talking a volume that is REALLY REALLY REALLY low. this is in the "high gain" mode.... and honestly, only deaf people would use this amp in high gain mode with low impedance phones!!! you can't hear the hum in low gain mode, even with the most sensative phones. to give you an idea of how much gain there is in high gain mode: the Grace uses a stepped attenuator. 3 clicks above no volume and it's already too loud to listen to. that's a rotation of about 1-2 hours. that's how loud the high gain mode is.

so, please don't worry about any Q.C. issues. it's not like that. we're talking the last bit of performance from an ultra-high performance amplifier. it's the Halcro of headphone amps. you know what i mean?

so, no fears on buying one, if you're considering it. it's the best. EVERY amp i have ever owned exhibited some form of hum on the most sensative phones. the 901 is by far the quietest of any of them, even without the transformer mod.

 

[Edwood]

But we demand perfection!

And it looks like Grace Designs delivers!

With a little bit of coaxing......

I'm so happy about the Balanced input rejection of the Ground Loop. Either that or the analog output stage bypass broke the loop. I will have to remember to test Iron_Dreamer's modded RME PAD for that. His is the unbalanced mod.

But yes, I never had the "constant" buzz.

gpalmer:
Is your buzz present only when you crank the volume with high gain switch on? With or without anything connected to analog inputs? i.e. with nothing playing, of course, crank the volume all the way up. Hit the "digital" switch. Do you notice a difference in noise?

-Ed