PPA values for Grado's?
Jun 3, 2004 at 2:40 AM Thread Starter Post #1 of 11

MN Ham Phones

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I'm driving myself crazy trying to choose values for R3, R4, R7, and C7.

Is a gain of 3 excessive for Grado's?

I'm looking for only reasonable gain and modest bass boost, when powering Grado's. I'll change the components later when I add to my collection of cans.

R3 1k
R4 1 or 2K
R7 3K
C7 .39uF

These are the values I'm looking at now. Any comments?

Tangent's calculators are great, but I'm looking for values you were satisfied with in a PPA with Grado's.

Thanks,
 
Jun 3, 2004 at 9:05 PM Post #2 of 11

DCameronMauch

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Hello. I would say a gain of 3 is quite excessive. According the the Grado Labs web site, every headphone they make is roughly 32ohms with 98dB SPL @ 1mVrms sensitivity. This must be a typo. Doing a web search revealed several sites which show the sensitivity is actually 98dB SPL @ 1mWrms. That's very different. I will be assuming you are using a standard 2Vrms line level source. So, 2Vrms yields roughly 125mW, and thus 119dB SPL. Should be more than loud enough. Unless you like physical pain and immediate permanent hearing damage. Basically, it looks like you don't really need any gain at all.

Update: Sent an email to Grado Labs asking for clarification.
 
Jun 4, 2004 at 2:48 AM Post #3 of 11

ITZBITZ

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I think the RA-1 has a gain of 4, based on the schematic. So a 1k/3k combo should handle it. You need to stick with 1K in R3, or else adjust R5/R1 to match the source impedence on the input to the PPA. R1=R3+R5
 
Jun 4, 2004 at 8:14 AM Post #5 of 11

Glassman

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what you really need for Grados is not voltage gain, but pretty good current capabilities, you should look for Diamond Buffer instead of those Intersils, they are nowhere as good as discrete buffer..
 
Jun 4, 2004 at 8:42 AM Post #6 of 11

rayofsi

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Quote:

Originally Posted by Glassman
what you really need for Grados is not voltage gain, but pretty good current capabilities, you should look for Diamond Buffer instead of those Intersils, they are nowhere as good as discrete buffer..


so whats holding up those diamond buffers?
600smile.gif
 
Jun 4, 2004 at 9:07 AM Post #7 of 11

Glassman

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Quote:

Originally Posted by ufokillerz
so whats holding up those diamond buffers?
600smile.gif



be prepared, they are comming soon!
biggrin.gif
 
Jun 9, 2004 at 9:28 PM Post #9 of 11

guzzler

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Quote:

Originally Posted by Jam_Master_J
I went with the default gain of 10 with my PIMETA. I just got rid of my SR-80s for MS-1s and will likely stick with Grado phones. Will I regret the gain of 10? I could still probably change my order if I act quick.


yes, it will really limit the volume control, and you'll be stuck at the bottom where the tracking isn't so good. Change to 2x or 3x

g
 
Jun 10, 2004 at 6:02 AM Post #10 of 11

doobooloo

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Quote:

Originally Posted by Jam_Master_J
I went with the default gain of 10 with my PIMETA. I just got rid of my SR-80s for MS-1s and will likely stick with Grado phones. Will I regret the gain of 10? I could still probably change my order if I act quick.


You'll also get a much higher noise level with higher gain. My biggest complaint with gain of 10.
wink.gif
 

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