How to stop Grado RA-1 hiss?
Jul 25, 2003 at 3:30 PM Post #16 of 40
Sounds like a rare problem unit. The gain shouln't be that high. I wonder if Grado mixed up the their Phono Unit board with the amp board.
 
Jul 25, 2003 at 5:43 PM Post #17 of 40
Holy Smoke! My retailer won't do an exchange for me. I wonder if I pissed them off somehow, but their attitude towards me seemed like they didn't want to deal with me anymore and they just wanted me to deal with grado myself or just return the unit and be done at that. No way am I returning it to lose shipping and a 20% restocking fee.

Guess I'm sending it off to Grado today and hope a perfect unit comes back to me.

By the way, on a working RA-1, where do you normally put the volume dial to listen with a grado headphone from a full size CD player? Assuming your volume dials all start at about 6'clock for 0 volume.
 
Jul 25, 2003 at 7:17 PM Post #18 of 40
Quote:

Originally posted by bcwang
Guess I'm sending it off to Grado today and hope a perfect unit comes back to me


Give Grado a call, as bootman suggested. They will take care of you.

Quote:

Originally posted by bcwang
By the way, on a working RA-1, where do you normally put the volume dial to listen with a grado headphone from a full size CD player? Assuming your volume dials all start at about 6'clock for 0 volume.


I listen between 7 and 9, with Grado phones.
 
Jul 25, 2003 at 8:00 PM Post #20 of 40
Oh, 7 to 9 seems pretty low too. I guess my amp wasn't that out of line. Oh well, I've already sent it off to Grado, so it looks like at least 2 weeks without the amp. It sounded great even though there was a hiss. I can't wait for it to come back.
 
Jul 26, 2003 at 3:08 AM Post #21 of 40
Likewise, between 7 and 9 o'clock with Grado headphones. If you want/need to get some attenuators like those made from Harrison Labs - there's -6dB and -12dB. Get the - 12dB if you want the volume pot to be in the 11 o'clock to 12 o'clock position. Do no that attenuators do change the sound. The attenuators go into the Amp RCA's. Good luck.

Also since you like in the US get the Painview rechargeable batteries as the RA-1 depend on battery output. As the batteries discharge (alkeline) the performance drops.
 
Aug 19, 2003 at 5:52 PM Post #22 of 40
Grado finally got to look at my ra-1 after being away from me for almost a month now. But they say it measures within spec and there's nothing wrong with it.

Does that mean it's only blind luck to get one that happens to be much quieter than another even though they are all within spec? I'm afraid even if they do send me another one it will have the same hiss problem. The person at Grado said they'll test my amp again tomorrow, but my feeling is it'll still measure the same, but if I got it back it'll still have the same hiss.
 
Aug 21, 2003 at 3:04 AM Post #23 of 40
Hello,

Another view:

I find that the ability to hear amplifer hiss in any equipment is directly related to the sensitivity of the headphones.

If the noise heard is coming from the Grado amplifier (which I believe it is) then attenuators at the RCA inputs will do nothing to eliminate the residual background hiss. Remember, this hiss is heard at the lowest setting. I'll even venture to say that the hiss in this Grado's case is heard with no equipment connected to it.

Some headphones, earbuds, etc. are incredibly sensitive. Sometimes 108db or more at 1kc for 1mw. Others are less sensitive and may be 95db at 1kc for 1mw. With the higher sensitivity the headphone will be touted as "easier to drive", "have more punch", etc. This increased sensitivity comes at a price - the ability to reproduce low level noise very efficiently, i.e. amplifier hiss. Another side effect is that the phone reaches listening levels so quickly that any possibile analog volume control non-linearities (typical at the beginning of the rotation) are going to be revealed resulting in unbalanced sound. Anyone desiring "high sensitivity" phones should consider these consequences. In my opinon and experience, given the "nosiness" of most of today's portable gear, a sensitivity spec of greater than 100db is going to have more negative consequences than positive.

Less sensitive phones while labeled "harder to drive" have some benefits: low level hiss may not be reproduced to audible limits, the phone while appearing to be "harder to drive" because of the increased volume control rotation necessary will allow the volume control to be utilized in more linear regions, thus resulting in better balanced sound. Might help keep one from blasting out their ears too.

Check the sensitivity rating of the phones you are currently using. If the rating is 108db, try using a pair spec'ed at 100db or less and see if the hiss goes away or is markedly reduced. If one is utilizing an outboard headphone amp, then the higher sensitivity phone (if it is being used for its "easy to drive" aspect) should not be necessary.

Otherwise, the solution is going to be:

1) To utilize some precision trim pots at the headphone output of the Grado (or any amp) to reduce the hiss below audibility when the Grado's volume control is turned all the way down.

2) A cheaper solution may be to utilize a separate stereo in-line volume control for headphones. Radio Shack sells them.

Best regards,

Paul
 
Sep 18, 2003 at 7:07 AM Post #24 of 40
Well, I just got my Ra1 back from Grado after over a month of tinkering with it over there. Actually, it's not the same one, because though they could find no problem with the unit I sent them, they tested another unit which they deemed fine and sent it to me. This unit has the exact same problem, excessive hiss.

I don't know if it's that I just have bad luck, or this is just the way it is and my hearing is too sensitive to this hiss. But I don't like this at all. I'm really liking my supermini now, it's almost completely silent, takes really hard listening in a really quite room to hear the background noise on that.
 
Sep 18, 2003 at 3:39 PM Post #26 of 40
I don't see this in any other posts....


Try another pair of headphones, maybe they are the cause of your hiss.
Also with a PCDP, I find with higher impedence headphones (like your Senns), you have to turn up the RA-1's to 1:00, to achieve the same sound than from a good AC CDP source at 10:00. (found out during blackout). When batteries fail, the sound gets fuzzy, not hissy.
 
Sep 18, 2003 at 5:52 PM Post #27 of 40
I did try more than one headphone, an RS1 and a HD497. I also used two fully charged plainview batteries, and also went and bought two brand new sanyo alkaline batteries just to see if it could be the battery. Same problem. Noticeable on the grado, terribly loud on the sennheiser. It's also not my headphones because both of them are pretty much silent on my supermini.

This unit is even more annoying in that at the very beginning of the volume stop, it is louder on the left side than the right. It doesn't equalize until it's quite loud, but at that volume it is louder than I'd like to listen to some of my music.
 
Sep 19, 2003 at 5:37 AM Post #28 of 40
Well... maybe the RA-1 isn't your cup of tea. Have someone build you an amp to suit your needs. Then you'll have a choice... you could sell the RA-1 or gut it and put your new amp in there. I seriously thought about gutting my RA-1and putting my JMT in there since to my ears it beats the RA-1's ass into the ground. Just can't justify tearing it up even though I hardly use it. Hmm... I could call it the JMT "Grado" mod!
 
Sep 19, 2003 at 6:32 AM Post #29 of 40
The only thing you can blame now is your IC. You use the same source and headphones, but the hiss only comes when your using the RA1. Im assuming your using a mini-to-rca IC for the supermini and an rca for the ra1 right?
 
Sep 19, 2003 at 8:46 AM Post #30 of 40
About the interconnect, it's not that for sure. I can have the RA1 with no inputs connected to it, just turn it on and plug in my headphones and there is the hiss. Do the same thing on my supermini and it's not there. I've also tried it with interconnects just in case anyway, same problem. Only difference with the supermini is I add an rca to mini adapter, and with the ra1 I don't use the adapter but just the interconnect.

The problem here is, I actually do like the way the RA1 sounds, except in the quiet parts of the music the hiss is really annoying. And the fact that others have said their units is dead quiet makes me wonder why my luck is so bad. And even two amps that grado checks out as working 100% ok has this hiss problem concerns me. Maybe only the lucky few get ones that don't hiss, but the majority hiss.
 
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