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Speaker amps for headphones - Page 101

post #1501 of 2933
Thanks brunk
post #1502 of 2933
OK - that's a plan I think I can execute. Thanks!
post #1503 of 2933
Quote:
Originally Posted by brunk View Post
 

Lol despite ALRAINBOW's scotch/iPad predicament, he is right. Just buy a bunch of these resistors -the cheap ones, and experiment. Get them in incremental values so you can mix and match easily, and use alligator test leads instead of soldering or whatever. I had a similar situation with finding a good crossover for my supertweeters. I bought a bunch of different value caps and played around until I found the best compromise.

Better yet, do a little math, consider what compromises you want to make, then buy a range of resistors around the solutions with those compromises accounted for THEN experiment...

post #1504 of 2933
Quote:
Originally Posted by potterma View Post
 

Better yet, do a little math, consider what compromises you want to make, then buy a range of resistors around the solutions with those compromises accounted for THEN experiment...

Yeah. I was just assuming that. :tongue: Have fun Mike!

post #1505 of 2933

One more thing...

 

If you feel extra adventurous, the overall best solution is to custom tailor the amp for said headphones. DiyAudio member OPC just so happens to have a very versatile speaker amp. Check it out here. Very portable too Mike. :evil:

post #1506 of 2933
Quote:
Originally Posted by potterma View Post
 

Better yet, do a little math, consider what compromises you want to make, then buy a range of resistors around the solutions with those compromises accounted for THEN experiment...

 

 

Oh, I'm running out of steam with this mysterious black art, but I'll bite...

 

With respect, I have to ask, what math?  The math I've done tells me there's an infinite number of solutions just to satisfy a single criteria - truly.  (That criteria being the previously discussed goal of outputting 1000mW into 50 Ohms - for the LCD-2 rev.1 - from an amp that's rated at 32Watts into 8-Ohms.) 

 

In truth, I don't even know whether I'll start hearing hiss from the MG3 at an output of 1000mW.  To state my goals as succinctly as possible, I want to get as close as possible to 13Wpc into 50-Ohm without hearing hiss - but I doubt there are any formulas that can predict the hiss, even if there are formulas that can predict the power output with various combinations of resistors.

 

So... Trial and error seems to be the only way to proceed - and I suppose it's a lot cheaper to experiment with a bunch of resistors than it is to experiment with a bunch of amps other than the MG3.  

 

:-)


Edited by zilch0md - 11/28/13 at 6:17pm
post #1507 of 2933
Quote:
Originally Posted by brunk View Post
 

One more thing...

 

If you feel extra adventurous, the overall best solution is to custom tailor the amp for said headphones. DiyAudio member OPC just so happens to have a very versatile speaker amp. Check it out here. Very portable too Mike. :evil:

 

Interesting....  You built one yet?  How's it sound with headphones?  Come on, we need a review!  :blink:

post #1508 of 2933
Quote:
Originally Posted by brunk View Post
 

One more thing...

 

If you feel extra adventurous, the overall best solution is to custom tailor the amp for said headphones. DiyAudio member OPC just so happens to have a very versatile speaker amp. Check it out here. Very portable too Mike. :evil:

 

Uggh!  

post #1509 of 2933
Yea me too brunk give it up man..
post #1510 of 2933
Quote:
Originally Posted by zilch0md View Post
 

 

Oh, I'm running out of steam with this mysterious black art, but I'll bite...

 

With respect, I have to ask, what math?  The math I've done tells me there's an infinite number of solutions just to satisfy a single criteria - truly.  (That criteria being the previously discussed goal of outputting 1000mW into 50 Ohms - for the LCD-2 rev.1 - from an amp that's rated at 32Watts into 8-Ohms.) 

 

In truth, I don't even know whether I'll start hearing hiss from the MG3 at an output of 1000mW.  To state my goals as succinctly as possible, I want to get as close as possible to 13Wpc into 50-Ohm without hearing hiss - but I doubt there are any formulas that can predict the hiss, even if there are formulas that can predict the power output with various combinations of resistors.

 

So... Trial and error seems to be the only way to proceed - and I suppose it's a lot cheaper to experiment with a bunch of resistors than it is to experiment with a bunch of amps other than the MG3.  

 

:-)

No, that's not the only way to proceed...  See my previous post.. If you want one watt into 60 ohms, the best attenuation you can get is about 5 dB.  Now, no, that doesn't say anything about the hiss.  That part of the problem I don't have any data on, so I can't state an opinion.  

 

Now, if you want 13 watts (I'm assuming RMS?) into 50 ohms you'll need an amp that can supply you with 25 VRMS (at 1/2 an amp) or 36 volts peak.  Don't know what you want to drive with that much power, but there are some target numbers for you.

 

That's sure not the MG3.  MG3 will only do 20 - 22 volts peak.

post #1511 of 2933
Quote:
Originally Posted by Chris J View Post
 

They are trying to attenuate noise.

 

With R1 = 8 Ohms and R2 = 2 Ohms you could easily (for example) reduce the volume (and also noise outputted by amp) by a factor of 5:1 (for example), i.e. 14 dB.

 

But we're talking about the LCD-2 here. You can achieve the exact same thing with a single 250 ohm series resistor. Because they're orthos, you don't have to worry so much about source impedance as you do with dynamics.

 

se

post #1512 of 2933
Zil the math is so you may have an assortment to use to acquire many of the combo,s needed to test your headphones.

Think of this has just using whole numbers . The fractions do not matter in this. An example would be what I posted

2, 3,5,10 ,20,30,50,100. In having about 10 of each you can play around and achieve good sound as well a resister network to lower the noise floor and increase the volume on the preamp, allowing getting closer to the sweet spot in the amp output. You will simple add the resistors when increasing the amount that is required.

You can use 10 represented as a 5,2,3. All In series and the output to your headphones across the 2 ohm resister .

Al D
post #1513 of 2933
Quote:
Originally Posted by Steve Eddy View Post
 

 

But we're talking about the LCD-2 here. You can achieve the exact same thing with a single 250 ohm series resistor. Because they're orthos, you don't have to worry so much about source impedance as you do with dynamics.

 

se

 

Sure that will work, but with the ability to only push 250 mW peak into the LCD-2.  Maybe not enough for transients.  

 

Let me throw out the disclaimer that I'm just working from specs, here.  I've never been fortunate enough to hear a pair of LCD's of any flavor...

post #1514 of 2933

OK, I'll just work on the unquantifiable hiss and ignore all the other criteria that are quantifiable.  

 

I'll just add series resistance, right?  Starting low and working my way up until the hiss is gone?  

 

At that point, I'll have as much voltage as possible in the absence of hiss.  Then I can do the math and see if I've got more than 124mW into 50-Ohms (as I do currently, with the TBI box).

 

Thanks again,

 

Mike

post #1515 of 2933
Quote:
Originally Posted by ALRAINBOW View Post

Zil the math is so you may have an assortment to use to acquire many of the combo,s needed to test your headphones.

Think of this has just using whole numbers . The fractions do not matter in this. An example would be what I posted

2, 3,5,10 ,20,30,50,100. In having about 10 of each you can play around and achieve good sound as well a resister network to lower the noise floor and increase the volume on the preamp, allowing getting closer to the sweet spot in the amp output. You will simple add the resistors when increasing the amount that is required.

You can use 10 represented as a 5,2,3. All In series and the output to your headphones across the 2 ohm resister .

Al D

Which will only give you 175 mW into the LCD's...

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