[dfarina]

I finally got my Ra-1 back from Grado,so far so good.I don't notice any extra noise from the conversion,and even though I have not had much time with it,to me it sounds the same except for one difference.The output of the amp seems to be much higher,meaning I do not have to turn the volume as high as I used to.My listening level has gone from the 12-1 o clock position to around the 11 o clock position,quite a noticeable difference.Seems kinda strange do to the fact the output of the adapter is 12v and .15 amps,compared to the 2 nine volt batteries??
Dave
http://www.pbase.com/image/14693242
http://www.pbase.com/image/14693245

 

[Sovkiller]

If I look correctly, you are running it now on +/- 12V instead of +/- 9V, it has to be a gain, the AC adaptor is giving it about 3 volts more per line.....

 

[dfarina]

Quote:

Originally posted by Sovkiller If I look correctly, you are running it now on +/- 12V instead of +/- 9V, it has to be a gain, the AC adaptor is giving it about 3 volts more per line.....

I believe the 2 nine volt batteries were wired in series giving it a total of 18 volts......not certain but I think that was the case.

 

[joelk]

Can I ask what Grado is charging for the conversion?

 

[dfarina]

Quote:

Originally posted by joelk Can I ask what Grado is charging for the conversion?

No problem,$75 rerturn shipping included.

 

[Sovkiller]

No they use 9 volt per line, if you want to use an external adaptor, before the mod, IIRC KR used two 9v eliminators from Radio Shack one for each side, I think that they are not on series, not according to the squematic... but you have +/-12V, that is 24 volts from one leg to the other, anyway is more voltage, if not, why do you think they used +/-12 instead of just 12? This cannon connector has at least three wires inside, one for +12, other for -12, and the ground, here is the squematic of the amp....


http://www.geocities.com/rubin_jpk/rubin/page_4c.html

 

[dfarina]

Quote:

Originally posted by Sovkiller No they use 9 volt per line, if you want to use an external adaptor, before the mod, IIRC KR used two 9v eliminators from Radio Shack one for each side, I think that they are not on series, not according to the squematic... but you have +/-12V, that is 24 volts from one leg to the other, anyway is more voltage, if not, why do you think they used +/-12 instead of just 12? This cannon connector has at least three wires inside, one for +12, other for -12, and the ground, here is the squematic.... http://www.geocities.com/rubin_jpk/rubin/page_4c.html

Sovkiller

Ok.............I got it now,I did not realize that the ac converter was like two units in one.It does have 3 wires coming out,two seperate 12 volts,and a ground.That explains why the amp has more output!!!!
Thanks
Dave

 

[sTaTIx]

Quote:

Originally posted by dfarina The output of the amp seems to be much higher,meaning I do not have to turn the volume as high as I used to.My listening level has gone from the 12-1 o clock position to around the 11 o clock position,quite a noticeable difference.

What headphones are you using with this amp? 12-1 o'clock seems kind of high to me, so I was wondering if you were using low sensitivity 'phones or Grados? Are you using a portable to drive this amp? Or maybe the Grado amp is just a low gain device?

 

[TimSchirmer]

Maaan that RA-1 is a sweet lookin amp...

 

[PatM]

I have the same question as STaTix. When using Grado phones, I cannot get the volume pot past the 8:00-8:30 position.

 

[Zanth]

Hmmm, my cd player must output some crazy volume...cause I can't listen louder than 7:00-7:30 position, I approach 8 on jamming albums and never past 9 even on the low level cds. 12? Damn...I'd be deaf.

 

[Eagle_Driver]

I agree with a lot of your replies about the Grado RA-1 (battery-powered) amp. The output - and sound quality - depends on which source that you're using to drive this amp. Portable MD units and Panasonic PCDPs cannot properly drive this amp even from their line-out (due to their relatively low output voltage), so you'll end up with *somewhat* weak, thin, overbright and shrill sound. The RA-1 amp works pretty well with Sony PCDPs (yep, even recent ones with a line-out) and the iRiver SlimX, but it really works best with standalone home component sources. I just have a feeling that the RA-1 amp requires a minimum of 0.5V (500mV) delivered from the device's line-out in order to properly drive the amp. Sony CD Walkman and iRiver SlimX PCDPs deliver adequate voltage from their line-outs, but Panasonics cannot (they are rated at 0.6V - but actually delivers only 0.3V from those line-outs).

It also depends on the batteries used. You see, alkaline 9V batteries actually lose voltage gradually over the life of the batteries, so that most "regular" alkalines will perform no better than a typical 8.4V/150mAh rechargeable NiMH battery - as far as sound quality is concerned. (In fact, the open-cell voltage of a 9V alkaline battery measures roughly the same voltage as a typical store-bought 8.4V NiMH or NiCd rechargeable battery.) "Ultra" or "high drain" 9V alkalines do perform somewhat better - but are they really worth double the price compared to "regular" 9V alkalines?

This is why I'm going to order two sets (four total) of the Plainview 9.6V NiMH rechargeable batteries, along with two of the Plainview chargers. You see why: Most commercially-sold NiMH chargers that can charge "9V"-size batteries can properly handle only the 7.2V batteries (the Energizer brand is the only brand of "9V"-size rechargeables that I know of that's rated at only 7.2V, most other brands are rated at 8.4V), since those chargers output only 9V to the batteries; the 8.4V batteries need at least 9.2 to 9.4V out of the charger in order to properly charge them. And of all the chargers that accept "9V"-size batteries that I currently own, only the earliest model of the Energizer ACCU charger (which is labeled CHM4AAWB) can properly charge 8.4V or 8.6V batteries, since that charger delivers 9.8V - the newer Energizer chargers output only 9.0V, which cannot properly handle 8.4V batteries.

 

[dfarina]

Quote:

Originally posted by Zanth Hmmm, my cd player must output some crazy volume...cause I can't listen louder than 7:00-7:30 position, I approach 8 on jamming albums and never past 9 even on the low level cds. 12? Damn...I'd be deaf.

There are a few factors that go into the volume level as previously stated.I have pulled off my volume knob,and maybe had replaced it in a different position than you,also the output of my cd player and so on. All these things were the same before and after the conversion,so a fair comparison can be made,and the AC version has a fair bit higher output.

http://www.pbase.com/image/14728145/large

 

[Zanth]

It must be the removal and replacement of the knob. No way 12 can be standard with grados...seriously...that is sooo loud