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M3 gain recommendations

post #1 of 22
10/12/09 at 1:55pm
Thread Starter 
So I am putting together my parts for an M3 build and I just can not decide where to go with the gain. Currently I listen equally to Grado SR225 and ATH-A900 headphones, neither of them require a great deal of gain. So with that in mind I was thinking of a gain of about 5. However I do plan to get a pair of HD650 and those probably need a bit more gain.

So I was thinking of have a gain switch. Does anyone have examples of how they integrated a gain switch into the M3? Would prefer a High/Low switch over variable gain.

Would a gain of 8x or 10x just be too much for the SR225?

Any suggestions?
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post #2 of 22
10/12/09 at 1:58pm
Depends on the output of your source as well. I used to have a balanced m3 that had gain of 1/3/5/7 (which when fed with a balanced source amounted to 1/6/10/14). Mostly I used 1. The higher options were for really hard to drive headphones like K1000s and K340s, or for speaker use.
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post #3 of 22
10/12/09 at 2:09pm
Thread Starter 
Quote:
Originally Posted by grawk View Post
Depends on the output of your source as well. I used to have a balanced m3 that had gain of 1/3/5/7 (which when fed with a balanced source amounted to 1/6/10/14). Mostly I used 1. The higher options were for really hard to drive headphones like K1000s and K340s, or for speaker use.
Well my source is a Y2. And this will strictly be for headphone use.
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post #4 of 22
10/12/09 at 2:12pm
What gain you choose also depends on how good your volume control is. With a great volume control (think RK50) you could just go with a gain of 20 and be done. Most volume controls are only good at the top portion of their range, so what gain you choose is more important. And if you go with a stepped attenuator, then the number of steps matters, as well.

That said, a 2 step gain, with 5 and 11 seems to be a popular option.
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post #5 of 22
10/12/09 at 2:23pm
Thread Starter 
Quote:
Originally Posted by grawk View Post

That said, a 2 step gain, with 5 and 11 seems to be a popular option.
Yeah I would like to implement a 2 step gain, does anyone have an example of how they achieved this? I would like to keep the signal wire here short but not sure how that is accomplished while having a front panel switch. Can this be done and still have the bass boost option? I know the shaping of the bass boost is tied to the Gain however when playing with the calculator changing R3 only does not seem to affect it by a great deal.
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post #6 of 22
10/12/09 at 3:08pm
Quote:
Originally Posted by grawk View Post
With a great volume control (think RK50) you could just go with a gain of 20 and be done.
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post #7 of 22
10/12/09 at 5:06pm
Quote:
Originally Posted by luvdunhill View Post
I think what he's saying is that with a pot that has excellent channel matching at even the lowest levels that you could be ok with an extremely high level of gain. I'd argue that 11 is more than enough for just about anything unless you have a low-output source or the K340s/K1000s. Me, I'd go with 2/8 if I was going to implement a switch.
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post #8 of 22
10/12/09 at 5:21pm
Even a gain of 5 will be too high for the A900. Switchable 2-5 or 2-8 would be my ideal choice.
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post #9 of 22
10/12/09 at 5:26pm
Thread Starter 
Ok so it is confirmed that a gain of 5 would be the max for my current phones, however I would think that this would be a little low for HD650. So switchable 2/8 would be a good thing.

Anyone have a Best Practice of how to accomplish this switchable gain? I know for the idea resistance to change would be R3, however to bring say a DPST switch on the front panel to switch between to resistors would add a good bit of wire to the circuit. Is this extra signal wire a concern?
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post #10 of 22
10/12/09 at 5:30pm
Quote:
Originally Posted by m1abrams View Post
however I would think that this would be a little low for HD650
Based on what?
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post #11 of 22
10/12/09 at 5:31pm
Quote:
Originally Posted by m1abrams View Post
Yeah I would like to implement a 2 step gain, does anyone have an example of how they achieved this? I would like to keep the signal wire here short but not sure how that is accomplished while having a front panel switch. Can this be done and still have the bass boost option? I know the shaping of the bass boost is tied to the Gain however when playing with the calculator changing R3 only does not seem to affect it by a great deal.
I would stick with a gain of 4x. That seems to work the be best with my 32 ohm grados, 64 ohm q40, and 80 ohm 770pros. The gamma 2 puts out alot of voltage. 1.4rms with the anticlipping. by contrast the bantam/alien do 1vrms, and the gamma1 does 1.6vrms, the highest ive seen is the grub that does 2vrms. that converts to;3.95,2.82,4.5,5.65 pp voltages.
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post #12 of 22
10/12/09 at 5:37pm
HeadWize: View Post [DIY Workshop » M³ Build Discussion]
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post #13 of 22
10/12/09 at 5:38pm
Thread Starter 
Quote:
Originally Posted by Beefy View Post
Based on what?
The fact that it is a high impedance phone that seems to benefit from high voltage swing.
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post #14 of 22
10/12/09 at 5:44pm
But saying higher than 5 is required is still pretty arbitrary
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post #15 of 22
10/12/09 at 5:50pm
Thread Starter 
Quote:
Originally Posted by Beefy View Post
But saying higher than 5 is required is still pretty arbitrary
Not currently owning HD650 I do not really know what is needed, so that is why I posted the question. I just had a feeling though that the gain requirements for my Grado are significantly different than what would be needed by say HD650. The Grados probably could do with less gain than 5x, however I am not sure what would be a good mark for the HD650. Note I did not say required either, just that they may enjoy the extra voltage swing that a higher gain would allow.
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