[BmWr75]

Thanks.  That one electronics course in college has come in handy over the years.  

 

[moodyrn]

Ha!!!!! Non of my courses have come in handy. Lol

 

[Shmitty]

Well some more trolling on craigslist and I found this

a Sony STR-6800 SD paid 150 probably could have gotten it a little cheaper but to be honest I could not be happier. A friend is going to stop by next week and we're going to go through it to see what we can do to clean it up a little and complete any service thats needed. My soundblaster 1240 is doing pretty good as a DAC for now but am still looking for some guidance there.

 

[Rawrbington]

Quote:

Ha!!!!! Non of my courses have come in handy. Lol

haha.  ain't that the truth.
 
great info from all of you guys.  greatly appreciated. 
now i just need to save up the dough for a pair of he-500.
 
thats a great lookin Sony you got there Shmitty!
too bad modern stuff doesn't look half as sexty

 

[Shmitty]

 
Quote:

Originally Posted by Rawrbington /img/forum/go_quote.gif
 
thats a great lookin Sony you got there Shmitty!
too bad modern stuff doesn't look half as sexty

Hey thanks! The lights don't work so it loses some cool points for looks so hopefully my friend can help me with that. HAPPY NEW YEAR YA'LL
doo doo doooo looking out my back door!

 

[Chris J]

 
Quote:

You're looking at it all wrong. Putting a 220ohm resistor at the headphone out doesn't make the output impedance 220ohms. It's just for lowering the gain since the headphone out is derived from the speaker taps. Actually, if they used a value higher than that, it would be a better match for 32ohm grados. If they only used a 32ohm resistor, grados would be fried. For example if the amp had a power rating of 80wpc at 8ohm, then with the 220ohm resistors the output would still be 2.5-3 full watts which is plenty for anything short an he-6 and grados would probably hiss like crazy without an additional -20db button.
 
My fisher tube integrated used 330ohm resistors at the headphone out and the speaker out wpc is only 25watts, and the headphone out was still plenty powerful the drive most headphones. But I did swap them out with lower ohm resistors to drive a pair of he-5's I use to have. But I may put the 330ohms back in since I won't be powering anything like that out of the headphone out anymore.

The output impedance of the CR-640 power amp ICs into a speaker is less than one ohm.
Yamaha then puts a 220 ohm resisitor in series between the power amp and the headphone jack.
This makes the output impedance at the headphone jacks approx. 220 ohms.
It doesn't alter the gain of the amp, it attentuates the signal from the power amp.
The reason why there are four resistors are:
two for each headphone jack
there are two for each headphone jack as one is for right channel, the other is for left channel.
 
However, you certainly are correct: the 220 ohm resistor limits the output to a 32 ohm Grado.
Historically, when the CR-640s were released, most headphones were 600 ohms or higher, for example, I used to use a 2,000 can with my CR-2020.
 
I calculated a few examples below:
220 ohms goes a long way towards protecting various value cans from frying.  (Slaps forehead!) So there is a point to having a large output impedance on this amp. (slaps forehead again!)

 


Quote:

Ohm's Law is V = I * R, where V = voltage, I = amperage and R = resistance
 
     or I = V / R is another way to state Ohm's Law.
 
Then, another useful equation is:  Power (P) = V * I
 
     So, P = V-squared / R if you substitute V / R for I in the equation above.
 
Let's now do the math on your receiver's headphone jack output..  Your receiver is rated to put out 45 watts (Power) at a load of 8 ohms (resistance) via the speaker outputs.    V-squared = 45 watts * 8 ohms, so V = 19 volts
 
Now we can calculate the Power output at the headphone jack using V = 19 volts and R = 220 ohms
 
P = (19*19)/220 = 1.6 watts at the headphone jack.
 
If I've messed this up, somebody speak up.

The math and formulas are absolutely correct, but we also need to take into account that the 220 ohm is in series with the headphone, so the headphone will get less than 1.6 Watts at clipping.
If we continue to use your 45 Watt amp example, and use some voltage divider math:
 
For example, for a 32 ohm Grado:
V = 19 * 32/(220+32)
   =  2.41 Volts
P = (2.41 * 2.41)/32
   =   182 milliWatts
 
For LSD,  60 ohms
V = 19 * 60/(60 + 220)
   = 4.07 Volts
P = (4.07 * 4.07)/60
   = 276 milliWatts
 
For a 600 ohm Beyer:
V = 19 * 600/(220 + 600)
   =  13.9 Volts
P = (13.9 * 13.9)/600
   = 322 milliWatts 
 
For 2,000 ohm 'phones:
V = 19 * 2000/(2000 +  220)
   =  17,2 Volts
P = 17.2 * 17.2 / 2000
   =  146 milliWatts
 
so should be able to drive the LCD-2 to ear bleeding volume.
you may need to lower the headphone jack impedance to drive HiFi Man HE-6, see Moodryn's post above.

however the headphone jack impedance is very high if that kind of thing concerns you......i.e. a headphone which needs a high damping factor and/or has an impedance which varies with frequency.
 
Oooops, I almost forgot......Happy New Year!
 
 
 
 

 

[Golfnutz]

Quote:

 

The output impedance of the CR-640 power amp ICs into a speaker is less than one ohm.
Yamaha then puts a 220 ohm resisitor in series between the power amp and the headphone jack.
This makes the output impedance at the headphone jacks approx. 220 ohms.
It doesn't alter the gain of the amp, it attentuates the signal from the power amp.
The reason why there are four resistors are:
two for each headphone jack
there are two for each headphone jack as one is for right channel, the other is for left channel.
 
However, you certainly are correct: the 220 ohm resistor limits the output to a 32 ohm Grado.
Historically, when the CR-640s were released, most headphones were 600 ohms or higher, for example, I used to use a 2,000 can with my CR-2020.
 
I calculated a few examples below:
220 ohms goes a long way towards protecting various value cans from frying.  (Slaps forehead!) So there is a point to having a large output impedance on this amp. (slaps forehead again!)

 


The math and formulas are absolutely correct, but we also need to take into account that the 220 ohm is in series with the headphone, so the headphone will get less than 1.6 Watts at clipping.
If we continue to use your 45 Watt amp example, and use some voltage divider math:
 
For example, for a 32 ohm Grado:
V = 19 * 32/(220+32)
   =  2.41 Volts
P = (2.41 * 2.41)/32
   =   182 milliWatts
 
For LSD,  60 ohms
V = 19 * 60/(60 + 220)
   = 4.07 Volts
P = (4.07 * 4.07)/60
   = 276 milliWatts
 
For a 600 ohm Beyer:
V = 19 * 600/(220 + 600)
   =  13.9 Volts
P = (13.9 * 13.9)/600
   = 322 milliWatts 
 
For 2,000 ohm 'phones:
V = 19 * 2000/(2000 +  220)
   =  17,2 Volts
P = 17.2 * 17.2 / 2000
   =  146 milliWatts
 
so should be able to drive the LCD-2 to ear bleeding volume.
you may need to lower the headphone jack impedance to drive HiFi Man HE-6, see Moodryn's post above.

however the headphone jack impedance is very high if that kind of thing concerns you......i.e. a headphone which needs a high damping factor and/or has an impedance which varies with frequency.
 
Oooops, I almost forgot......Happy New Year!
 
 
 
 

When I had my LCD-2's plugged into my CR-2020, I couldn't get the volume level to 1. It was just too loud. Same thing with the HD800.
 

 

[Chris J]

Quote:

When I had my LCD-2's plugged into my CR-2020, I couldn't get the volume level to 1. It was just too loud. Same thing with the HD800.
 

I will resist the impulse to ask you if the volume control went to 11! 

 
Did you try pushing in the "Audio Muting" button?  It reduces output by -20 dB which is significant!
The only other thing I can add to this is that 25-30 years ago my brother and I had:
1 pair of Sennheiser HD424
1 pair of AKG K241
1 pair of Koss headphones that looked kind of like Grados, they had a volume control on each ear!
 
We would often listen to music at the same time thru the two headphone jacks late at night.
We never had any problems with excessive volume or getting the right volume with any of those cans.

 
 

 

[Golfnutz]

Quote:

I will resist the impulse to ask you if the volume control went to 11! 

 
Did you try pushing in the "Audio Muting" button?  It reduces output by -20 dB which is significant!
The only other thing I can add to this is that 25-30 years ago my brother and I had:
1 pair of Sennheiser HD424
1 pair of AKG K241
1 pair of Koss headphones that looked kind of like Grados, they had a volume control on each ear!
 
We would often listen to music at the same time thru the two headphone jacks late at night.
We never had any problems with excessive volume or getting the right volume with any of those cans.

 
 

Good idea...
 
Loudness set to 10 (off), Audio Muting -20 db, Volume is now at 2 (out of 10).
 
Thanks!
 

 

[cifani090]

Has anyone here listened to headphone on a big Sansui, like a G-22000 or 33000?

 

[Meewoo]

Never see super big G in this thread. I think Skylab's SX-1980 is the biggest one in this thread.

 

[Rawrbington]

does anyone really own a G 33000?
 
i bet they go for more than my car

 

[Chris J]

Quote:

Good idea...
 
Loudness set to 10 (off), Audio Muting -20 db, Volume is now at 2 (out of 10).
 
Thanks!
 

Hi,
 
For flat response turn the Loudness knob fully Clockwise.  I always thought it was a weird feature......probably 'cos I never used it!  LOL
 
C.
 

 

[Shmitty]

Ya'll are killing me someone give me some opinions on a DAC under 200 dollars for my SRT-6800 as pictured above I'M OPEN TO ABOUT ANYTHING.

 

[singh]

the g22000 and the g33000 have power-pre parts , so i guess the headphone jack on them wont be that powerful.
 
yeah the sx-1980 might be the biggest , but i doubt its the best sounding, i think the best sounding one here is the au-20000 or the yamaha B1-C1 power pre.