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Could someone recommend an amp for m50s

post #1 of 10
12/18/10 at 6:13pm
Thread Starter 

Howdy, my friend told me he would like an amp and DAC to go along with his new m50s that he's getting for Christmas. I was thinking that he should get a grubDAC and a Mini3, but I was curious if anyone would recommend an alternative. The phones will be used as his home pair, so a desktop amp isn't out of the question.

 

His budget is ~100-120 with an amp and DAC. 

 

I haven't actually heard an m50, so I don't really know what to recommend him as far as amps go.

 

I'd appreciate your help.

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post #2 of 10
12/18/10 at 7:24pm

The m50s are very sensitive.  The Mini3 would be fine with low gain (2x gain).  I'd go further and say just a unity gain buffer.  The M50s really need no gain.

 

a20 or JISBOS would be a good choice, IMO, with a pot in front.

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post #3 of 10
12/18/10 at 10:33pm
Quote:
Originally Posted by holland View Post

The m50s are very sensitive.  The Mini3 would be fine with low gain (2x gain).  I'd go further and say just a unity gain buffer.  The M50s really need no gain.

 

a20 or JISBOS would be a good choice, IMO, with a pot in front.



 I would agree. I've got a GrubDAC and Mini^3 with the default 5x gain with my M50s, I normally have 15dB of attenuation in fb2k on my laptop and then I still don't turn the volume pot much past 9 o'clock. I'm planning to swap the resistors for 2x gain but am wondering if that will still be fine when I get my HD650s.


Edited by porthillsbomber - 12/18/10 at 10:39pm
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post #4 of 10
12/18/10 at 11:13pm
Quote:
Originally Posted by porthillsbomber View Post

 I would agree. I've got a GrubDAC and Mini^3 with the default 5x gain with my M50s, I normally have 15dB of attenuation in fb2k on my laptop and then I still don't turn the volume pot much past 9 o'clock. I'm planning to swap the resistors for 2x gain but am wondering if that will still be fine when I get my HD650s.


I'm using a gain of 2 in my M³. No problem at all with the HD650s. (Nor with the M50s, but that's a given.) You get lots of room to play with on the volume knob to get it to just the way you like. 12 o'clock is the highest I can turn it up with the HD650s before it gets uncomfortably loud. This is with the gamma2 as source, btw, so YMMV.

 

This also depends on the pot used. I'm using the default 50KΩ one in the M³. The Mini³ on the other hand, has a 10KΩ default pot. OP, see if you can get a higher Ω pot for the Mini³, even if you use the lowest gain option. You'll minimize the channel imbalance issues that most pots have at the lowest levels that way. Just in case your friend wants to listen to some soft music before bed or something.

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post #5 of 10
12/19/10 at 12:52am
Thread Starter 

Well, it sounds to me like the m50s don't really need an amp. Would my friend be better off with a cmoy?

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post #6 of 10
12/19/10 at 10:10am
Quote:
Originally Posted by BobSaysHi View Post

Well, it sounds to me like the m50s don't really need an amp. Would my friend be better off with a cmoy?


Sure, just use low gain or unity gain.  All you really need for the DAC is a buffer, to make a line out stage, but with a pot in the middle (pre-amp style).  I understand your budget is low, but you should be able to build a Pimeta-style buffered opamp fairly cheap, especially if you use PC board.

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post #7 of 10
12/19/10 at 2:09pm
Thread Starter 

Ok, thanks for your help. I haven't ever actually built anything on PC board before (haven't even built a cmoy, but I have a lot of experience building on pcb boards), but I have to learn how eventually.

 

I'll come back if I have any questions.

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post #8 of 10
12/23/10 at 3:38pm
Thread Starter 

I'm back, confused and obviously in over my head.

 

I'm confident I can copy a design/layout, but I don't think I can create one. I was thinking an apheared 47 or just straight up cmoy. Would I just use a higher resistance to lower the gain? I've been reading about amplifier design, but I lack a basic electronics background, so most of it is lost on me (I just ordered several textbooks that should help with this, though).

 

I found this (http://williamneo.blogspot.com/2008/03/grado-ra1-headphone-amplifier.html) and while it's the most basic of basic, I figure it would work. I'd use the virtual ground, and several higher end capacitors. 

 

Will that do? Is there anything I should modify on this circuit?

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post #9 of 10
12/23/10 at 6:08pm

I like the Pimeta. The circuit is simple, and the class A stuff (transistors, two LEDs, trimpot, and some resistors) can be omitted. I don't recommend PC board though since the original PCB has four layers (IIRC), and the buffers are all SMD unless you go with Pimeta v1. I like the RK27 and dislike the RK097, and the M50s does benefit from the better channel tracking.


Edited by ShinyFalcon - 12/23/10 at 6:13pm
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post #10 of 10
12/23/10 at 6:19pm
Thread Starter 
Quote:
Originally Posted by ShinyFalcon View Post

I like the Pimeta. The circuit is simple, and the class A stuff (transistors, two LEDs, trimpot, and some resistors) can be omitted. I don't recommend PC board though since the original PCB has four layers (IIRC), and the buffers are all SMD unless you go with Pimeta v1. I like the RK27 and dislike the RK097, and the M50s does benefit from the better channel tracking.


I'll pass it along.  I'll have to see if he's willing to pay extra for it. It would simplify things a lot though.

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