[TKSingh]

Hi All,
I am still waiting on my Wheatfield HA-1 and a pair of Senn 600's BUT, my first impressions of Grado 325 through my receiver's(Yamaha RX-V2200) headphone output are:

Sound is good, need to turn up the volume, but no where near my expectations. I have been reading lots about the ease of driving Grado's but really it is not that great out of the reciever. The headphone jack is rated at 150mV/100OHMs.

Here is hoping that the Wheatfield makes them come alive !

Ken

 

[Eagle_Driver]

Guess what? Blame your receiver's headphone jack for your problems with the SR-325's. Grados have an impedance rating of only 32 ohms, compared to the 100-ohm output impedance of your receiver's headphone jack. The end result of such impedance mismatching includes (but not limited to) the following:

1. Bloated mid-bass response,
2. Reduced volume,
   OR
3. Increased likelihood of clipping and distortion at even moderate volumes.

Headphones should have an impedance that's higher than the output impedance of a given jack just to sound decent. Unfortunately, Grados just happen to be a poor match for most receiver headphone jacks; they sound best from a jack with an output impedance of less than 10 ohms.

 

[Joe Bloggs]

Build the impeder to fix that! (see signature below)

(my standard greeting this week?

)

 

[TKSingh]

Eagle D,
does this mean my Senn600 would probably be driven better out of the receiver jack ?

Cheers
ken

 

[TKSingh]

Well, Got Senn's today and my Amp. No time to set up the amp, but the 600's seem very similar out of the receiver, maybe more bass ! Still need to turn the volume up a lot, sounds compressed. Anyway the real review to follow this weekend, Grado 325, Senn 600(stock cable

) and Wheatfield HA-1...

Cheers
Ken

 

[Spad]

I think you may be misinterpreting the 150mV/100 ohms spec. Unless I'm mistaken, the 100 ohms is not the output impedance of the jack, but rather the reference load for the 150mV power output.

Spad

 

[Eagle_Driver]

Quote:

Originally posted by Spad I think you may be misinterpreting the 150mV/100 ohms spec. Unless I'm mistaken, the 100 ohms is not the output impedance of the jack, but rather the reference load for the 150mV power output. Spad

That would have resulted in a power output of only 0.225 mW (225 uW) at 100 ohms, or only 1.4 mW at 16 ohms! That's much weaker than even a PCDP!

 

[ServinginEcuador]

Quote:

Originally posted by Eagle_Driver That would have resulted in a power output of only 0.225 mW (225 uW) at 100 ohms, or only 1.4 mW at 16 ohms! That's much weaker than even a PCDP!

Actually..... the rating IS 150mW @ 100 ohms Therefore at:

32 ohms he should get something like a potential of 450mW.
16 ohms he should get something like a potential of 900mW.

As the resistance of the load goes down the potential and ease of making power goes up also. That's why most speaker amps rate their power at 8 ohms, then it is usually, but not always, doubled for 4, and doubled again at 2 ohms.

P=IE
P=E^2R
P=I^2/E
E=P^2*R

 

[Eagle_Driver]

Quote:

Originally posted by ServinginEcuador Actually..... the rating IS 150mW @ 100 ohms Therefore at: 32 ohms he should get something like a potential of 450mW. 16 ohms he should get something like a potential of 900mW. As the resistance of the load goes down the potential and ease of making power goes up also. That's why most speaker amps rate their power at 8 ohms, then it is usually, but not always, doubled for 4, and doubled again at 2 ohms. P=IE P=E^2R P=I^2/E E=P^2*R

Well, you're confusing mV (millivolts) with mW (milliwatts). And the only way that 150mV can equal 150mW is if the load impedance is only 0.15 ohm (150 milliohms).

 

[ServinginEcuador]

Eagle,

You're right about that. I was assuming that is was a typo and the original post was supposed to be 150mW, not mV. Since 150mV is WAY too little voltage for any headphone jack to put out, again I assumed it was mW instead. It is usaully more like 2-8 full volts, not millivolts.

Good catch on that one!! I've not seen a manufacturer give a rating to their headphone jack output in voltage. It is always in mW. didn't mean to correct you or start a contest about who was right. I just made the assumption and went with it. Apologies to you Eagle_Driver.

 

[Spad]

Quote:

Originally posted by ServinginEcuador Eagle, You're right about that. I was assuming that is was a typo and the original post was supposed to be 150mW, not mV. Since 150mV is WAY too little voltage for any headphone jack to put out, again I assumed it was mW instead. It is usaully more like 2-8 full volts, not millivolts. Good catch on that one!! I've not seen a manufacturer give a rating to their headphone jack output in voltage. It is always in mW. didn't mean to correct you or start a contest about who was right. I just made the assumption and went with it. Apologies to you Eagle_Driver.

I missed the typo as well and just copy/pasted the numbers as they were stated. Obviously he didn't mean mV since this would indicate a totally useless headphone out, and Yamahas have among the best.

Reminds me of the $150M Mars probe that missed the mark because one group used the metric system while the other did not.

Spad

 

[ServinginEcuador]

Quote:

Originally posted by Spad Reminds me of the $150M Mars probe that missed the mark because one group used the metric system while the other did not. Spad

I remember that fiasco. What a waste of money. Then there was that little multi-million dollar rover they used on Mars. It worked for a little while then went away. Those guys should be fired and teh money used for something really important here in our own country. But I digress into a canof worms I don't want to open up.

Thanks for the post Spad. Always good to hear from you.