[jinschoi]

I built a cmoy as my first project some time ago, and more recently an extended life version of the mini3. I've been enjoying the mini3 with HD650s from a gamma1 source, but I just went back to the cmoy and found to my surprise that in some ways I like the sound better. In all respects, looking at their data sheets, the LMH6643 should be a better opamp than the Burr Brown OPA2132PA, but the latter just seems to have more impact with certain genres of music. Clearer high frequency transients such as cymbal hits and chimes, better resolution, drumming has more presence... I don't know quite how to describe it, but switching back and forth made it clear that the cmoy isn't entirely subsumed by the mini3, for me.

This is surprising to me because the cmoy is the basic build from tangent's site: doesn't use a rail splitter, has output caps. What could account for this? Maybe it's just personal preference, as the OPA2132PA has been described as having "tubby" bass and I'm just picking up on that. Maybe it's because the op amp has more headroom, being driven from external 12V rather than a 9V battery? Although the LMH6643 should have better output current, and can get plenty loud.

Thoughts?

 

[lutwey]

i would say its personal preference. one quetion though. do you listen at a low volume. im asking because a cmoy would not be able to power the senns adequately. if i have the diy skills ill look in to building an m3 w/ sigma 11......then i would guess youll start hearing significant difference.

 

[JamesL]

When I entered headfi, my listening preferences were all over the place. and they still are a little, though it's settled down quite a bit. One day, I'm admiring the sound of my new hd650's and thinking my d1000's terribly muddy and flat. Next week strongly preferring my d1000's over my hd650's. At one time, I preferred my computer output (apparently, it has really small output caps), and now, I can't stand listening to it's overall shoutiness, dryness, and complete lack of bottom end.

Quote:

What could account for this?

My guess is that it doesn't have anything to do with any measurable quality of the sound, but just signature of the sound that your brain is adhering to.

 

[jinschoi]

I normally listen at fairly low levels, but I turned it up to get a good feel for the sound.

I never quite understood how to determine how much current a particular set of phones will need. The Sennheisers have an input impedance of 300 ohms. Doesn't that indicate that they would be easier to drive than IEMs with 30 ohms? cmoy has 40 mA output current, the mini3 about 70 mA. How much does the M3 put out?

I'm very tempted to try my hand at an M3 build, but have been putting it off because I'm uncomfortable with casing work. I haven't researched it yet, but any comments on what would be the easiest casing options with the least amount of special case work necessary would be helpful.

 

[amb]

Quote:

Originally Posted by jinschoi /img/forum/go_quote.gif How much does the M3 put out?

Many amperes, practically limited only by the powers supply. Much more than what a HD600 would draw.

 

[Earwax]

Quote:

Originally Posted by jinschoi /img/forum/go_quote.gif Maybe it's because the op amp has more headroom, being driven from external 12V rather than a 9V battery?

That would be my guess.

 

[gurusan]

My cmoy uses a rail splitter and is driven from 15V....it sounds ok but my Millet SS sounds much better....I have a mini3 kit on its way to me so I hope it sounds better than the cmoy!

 

[amb]

Quote:

Originally Posted by jinschoi Maybe it's because the op amp has more headroom, being driven from external 12V rather than a 9V battery?

Sorry, no. The LMH6643 (Mini³ extended runtime) and AD8397 (Mini³ high performance) are both rail-to-rail opamps and can swing voltage to within ~0.2V or each rail (even when loaded with low-Z loads). The OPA2132 is not rail-to-rail, not even close. Either edition of the Mini³ running on a single 9V battery can swing more voltage than a cmoy on 12V, and could match a cmoy on two 9V batteries.

Btw, the LMH6654 and AD845 are not rail-to-rail either.

 

[andrew3199]

Quote:

Originally Posted by amb /img/forum/go_quote.gif Sorry, no. The LMH6643 (Mini³ extended runtime) and AD8397 (Mini³ high performance) are both rail-to-rail opamps and can swing voltage to within ~0.2V or each rail (even when loaded with low-Z loads). The OPA2132 is not rail-to-rail, not even close. Either edition of the Mini³ running on a single 9V battery can swing more voltage than a cmoy on 12V, and could match a cmoy on two 9V batteries. Btw, the LMH6654 and AD845 are not rail-to-rail either.

So are you saying that the Mini³ would do a good job at driving the Senn HD600's?

 

[amb]

Quote:

Originally Posted by andrew3199 /img/forum/go_quote.gif So are you saying that the Mini³ would do a good job at driving the Senn HD600's?

"Good job" is a relative word. But yes, the Mini³ does a respectable job of driving the HD600s, as good as an amp could with only one 9V battery as the power source, and does not pale in comparison to many others with two 9Vs.

 

[Llama16]

I use my Cmoy (1 9V battery) to drive my HD650, They do a great job. Very clear sound and no hiss at all. I prefer using these headphones with my Cmoy over some 32ohm ones

Dries

 

[amb]

Quote:

Originally Posted by Llama16 /img/forum/go_quote.gif I use my Cmoy (1 9V battery) to drive my HD650, They do a great job. Very clear sound and no hiss at all. I prefer using these headphones with my Cmoy over some 32ohm ones Dries

If you like the cmoy with HD650s, then you're really going to like the Mini³.

 

[andrew3199]

There are reviews on this site that compare the Mini³ to some of Ray Samuels amps. There are people that actually prefer the Mini³ to the SR-71. I think Ray also tuned his amps using Senn headphones. A quick search should find the comparisons.

 

[pdupiano]

I'd vote for the mini3 and use a dedicated psu rather than the battery. As far as I'm concerned, the Mini3's one of the most powerful "portable" amps I've listened to. The reason why it's "Portable" is that I rarely used it for portability, I wound up using it at a desktop amp at my lab. The SR71A is probably the only one that could drive the hd650's using actual portable power supplies (Batteries not wallwarts). On a side note you could try other DIY amps that use 2 9v batteries, add an opamp socket and you're in business.

 

[amb]

Yup, when running on wallwart power, the Mini³ supply rail voltage increases to 12V (regulated internally), so its maximum output voltage swing increases a little bit over battery power (which also depends on the state of battery charge). The increase is not large (about 2-3dB typical), but it's there.