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Speaker amps for headphones - Page 105

post #1561 of 2631
Yes no hiss when music is playing
post #1562 of 2631

That sounds more like a fault in the source than the amp. What if you play a blank track?

post #1563 of 2631
Quote:
Originally Posted by ALRAINBOW View Post

Yes no hiss when music is playing

Then I wouldn't worry about it. Unless of course you prefer to sit listening to silence instead of music. biggrin.gif

se
post #1564 of 2631
Lol. I understand it is not broke.

Al D
post #1565 of 2631

I understand how to calculate resistance with combined parallel and series resistance but I don't understand how the Resistance In and Resistance Out in this schematic was calculated. Could someone give a brief explanation?

 

 

Also, how was the Attenuation calculated?

 

Thanks in advance,

Rob

post #1566 of 2631

Search me!  (But I feel for you!) 

post #1567 of 2631
Quote:
Originally Posted by robrob View Post
 

I understand how to calculate resistance with combined parallel and series resistance but I don't understand how the Resistance In and Resistance Out in this schematic was calculated. Could someone give a brief explanation?

 

 

Also, how was the Attenuation calculated?

 

Thanks in advance,

Rob

What amp was this calculated for?  Either they are using the output impedance of the amplifier as part of the Resist Out (as they should) or I'm missing something...

 

Their "attenuation" doesn't take into account the impedance of the headphone, so Attenuation is calculated wrong.  It would be close for anything 600 ohms and higher.

The "attenuation" they have calculated is just the voltage divider ratio:  Vin/Vout = (R2 + R3)/R3

 

Resist In (the resistance seen by the amplifier) is calculated as R1 || (R2 + R3).  But, the impedance of the headphone is not included in the calculation, so its not quite right.  You need to put (R4 + Rheadphone) in parallel with the above so you'd have  R1 || (R2 + R3)||(R4 + Rheadphone)

post #1568 of 2631

Thanks potterma, I don't know what amp or phones this was calculated for. It's the translation from Italian of the network posted very early in this thread.

 

Is Resist Out the resistance seen by the headphones? (((Amp Impedance || R1) +  R2) || R3) + R4

post #1569 of 2631

I have a Lyr which I I love, but Steve Eddy made me some speaker adaptors, so I can connect my Trends amp too (I just wanted to experiment).  Not using any resistors, I hear a lot of hiss with the Trends amp, however it does sound quite different from the Lyr, and when music (at least compressed music) is playing, I don't hear the hiss - it sounds very good considering it is a suboptimal setup.

post #1570 of 2631
Quote:
Originally Posted by robrob View Post
 

Thanks potterma, I don't know what amp or phones this was calculated for. It's the translation from Italian of the network posted very early in this thread.

 

Is Resist Out the resistance seen by the headphones? (((Amp Impedance || R1) +  R2) || R3) + R4

Yes, resist out is apparently the resistance seen by the headphones.

I knew I had seen that circuit somewhere before, but it was too long ago... Didn't remember it was from this thread... :confused_face_2:

 

Anyway, why the interest in such a complicated network?  

 

Quote:
Originally Posted by NinjaHamster View Post
 

I have a Lyr which I I love, but Steve Eddy made me some speaker adaptors, so I can connect my Trends amp too (I just wanted to experiment).  Not using any resistors, I hear a lot of hiss with the Trends amp, however it does sound quite different from the Lyr, and when music (at least compressed music) is playing, I don't hear the hiss - it sounds very good considering it is a suboptimal setup.

 

And so, the adventure begins... :D

post #1571 of 2631
Quote:
Originally Posted by potterma View Post
 

 

 

And so, the adventure begins... :D

 

I need to get my SET 300b amps up and running again - I expect to be amazed !  :beerchug:

post #1572 of 2631
Quote:
Originally Posted by NinjaHamster View Post

I need to get my SET 300b amps up and running again - I expect to be amazed !  beerchug.gif

Be sure and post your results!
post #1573 of 2631
Quote:
Originally Posted by potterma View Post


Be sure and post your results!

Will do !

post #1574 of 2631
Quote:
Originally Posted by robrob View Post
 

I understand how to calculate resistance with combined parallel and series resistance but I don't understand how the Resistance In and Resistance Out in this schematic was calculated. Could someone give a brief explanation?

 

 

Also, how was the Attenuation calculated?

 

Thanks in advance,

Rob

 

I can't think of any arrangement where you would need R4 in that diagram.

 

R1 is roughly the load your amp sees, and is only important if your amp needs a specific load to run optimally

R2 and R3 form your voltage divider

R3 is roughly the output impedance seen by the headphone (assuming R3 is small, which it should be)

post #1575 of 2631
Quote:
 Anyway, why the interest in such a complicated network?  

 

I'm working on a spreadsheet that will calculate values for networks using 4, 3, 2 and 1 resistors.

 

If you only use R1, the amp load resistor, will that affect the impedance the headphone sees too? It seems like it would.

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