Review: Rockhopper Audio M3
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tkam

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Review: Rockhopper Audio M3

Intro

It’s been a few months since I’ve bought anything headphone related and after hearing a M3 at the Maryland meet in mid April the time to try something new bug bit. I decided I could really use one at work with my mp3 player (H320) and as secondary amp to the Dynahi. After e-mailing back and forth with thrice (Stephen, Mr. Rockhopper Audio himself) I settled on having him build me one of his Home M3’s with a few extras. The whole process from initial inquiry to delivery was both smooth and pleasant. Stephen kept me up to date on the progress of the amp including a few small delays, the first due to him changing to the new and much nicer cases and the 2nd believe it or not was due to a delay in the supplier shipping him the shiny new knobs (they are really, really shiny
. The delay was really quite short and Stephen was very professional throughout the whole process. Photos and specs of the amp are listed at the bottom of this review. Ok on to the stuff that everyone really wants to read….

Build Quality and Looks

The new cases Rockhopper are using for the M3 Home Edition are solidly built and look exceptional. The case has a nice anodized silver finish and big shiny knobs for volume control, variable bass boost and selectable inputs. The amp would look right at home on a store shelf somewhere. There is zero flex in the panels and the case has a solid feel with more weight to it than one might expect. The three knobs also have a good feel to them. The volume knob smoothly clicks along through the DACT’s steps. The bass boost knob tracks very smoothly and the input selector knob clicks into its three available positions. It also has three relatively large feet on it which hold it firmly in place on my audio rack. I can safely say it’s one of the nicest looking and well built cases I’ve seen especially from the DIY-esque small manufacturers.

Sound

Usually when I purchase something I have a pretty solid idea in my mind what it is going to sound like. Well this time I thought I had a pretty good idea but I was quite wrong. I thought it would be a warm sounding solid state amp similar to the HR-2 but after having the amp for awhile I think it’s actually closer to the typical tube sound. It has a really strong, deep bass and a full, liquid mid range. It also has that pleasant gentle roll off in the upper treble region that is typically found in tube amps. It’s not a drastic roll off but the treble can get lost in the music with the pronounced midrange that the M3 has. The M3 has very good bass it’s very deep and powerful but does have a tendency to be a little bloated sometimes. Upper bass and mid range are the real strengths of the M3 as they both have a fullness and liquidity that most solid state amps in this price range can’t touch. The treble has a clean and coherent sound and there is a little bit of roll off in the upper registers but I don’t think there is too much if any detail loss because of it. The M3’s tonality really does remind me of a tube amp it has a very rich “musical” sound. As I think about it the best words to describe the sound are “refreshing and soothing.” It’s not overly analytical and wouldn’t point out every mistake in a poor recording but it’s also not going to gloss over them. It’s like the mild mannered bully, a nice pleasing sound but you know there’s a lot of power and it’s not afraid to use it.

Comparisons

I have done some direct comparisons with the Dynahi but before I get to that I want to mention how I think the M3 matches up against two of my most recent amps, a high end PPA and the Melos SHA Gold. I always liked the PPA it was a pretty decked out one, but from memory it had nowhere near the mid range presence of the M3. The PPA’s treble was more extended but it was a less coherent amp than the M3 is. If I was in the market and had my choices down to a PPA or M3 I’d go with the M3 almost every time, it’s considerably less expensive and provides a richer sound. On to the Melos, I actually think the M3 has a very similar sound to the Melos it has that same rich powerful tonality about it. I’d be hard pressed to say which one is better, the Melos had better bass but the M3 has more precise imaging and separation it would come down to personal preference more so than quality.

Now the Dynahi comparison, I’ll get this out of the way quickly the M3 is not as good as or better than the Dynahi. This is not a knock on the M3 at all my Dynahi cost twice as much as my M3. If anything I was surprised at how well the M3 held its own in this comparison. Bass response is pretty even but the Dynahi has much better control and goes a little deeper. The Dynahi’s bass also has greater impact and is much quicker. The mid range comparison was by far the most evenly matched. The Dynahi is cleaner and more transparent but the M3 is pretty much neck and neck when it comes to tonal accuracy and liquidity. The M3 stays pretty close through sound stage, separation and imaging comparisons. It takes a bit of a beating when it comes to the treble though the Dynahi’s extension and speed are too much for the M3 and it just can’t keep up. I’m going to say that the M3 gets you roughly 80% of the Dynahi’s quality and keep in mind that it is half the cost.

Conclusions


I really do like the M3 and it would choose it over any amp under $500 it’s tube like tonal quality and solid state precision make it a truly versitale amp. The M3 can also drive any headphone on the planet, it very easily drove my PS-1, HP3000 and K3000.

The Rockhopper Audio M3 is a very fine headphone amp and deserves to be considered in any conversation of the under $1000 headphone amps. It has certainly earned a right to be mentioned there. I want to congratulate the M3 team for the great design that I’m sure will lead to many happy hours of listening and I also want to thank Rockhopper for the great product and even better service.

Photos








Specs

Clear anodized aluminum enclosure
STEPS PSU
Elna Cerafine Electrolytic Caps
Wima and Vishay Roderstein Film Caps
Vishay-Dale Resistors
Solen Caps for the Bass Boost
DACT Stepped Attenuator
ALPS Blue for Bass Boost Control
OPA637 for gain channels 627 for ground
Neutrick headphone jack
Cardas CTFA RCA jacks for 3 inputs and 1 loop out
MOSFET and Op-amp Biased to 80ma per channel
Variable Bass Boost
 
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amb

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Thanks for the excellent review. When you get a chance, it would be interesting to roll some different opamps in your M³ (e.g., AD8610, AD8065 or others) and do another round of comparisons. Tests show that the M³ with any of these opamps has flat frequency response up into the MHz range with no "roll off", nevertheless the Burr-Brown opamps are said to have a laid-back sonic signature, perhaps the AD opamps will bring out the top-end a bit more.
 
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Quote:

Originally Posted by amb
Tests show that the M³ with any of these opamps has flat frequency response up into the MHz range with no "roll off", nevertheless the Burr-Brown opamps are said to have a laid-back sonic signature, perhaps the AD opamps will bring out the top-end a bit more.


This is a very interesting aspect of psycho-acoustics.
I guess every modern opamp and even the older ones have a totally flat frequency response curve within human perception range and widely into infra- and ultrasound.
Where do the different sounds of opamps come from? Why do we talk about more extended bass, "roll off" or veiled highs and "liquid midrange". Is it harmonic distortion? - in case of tube amps, I believe this is important, on the other hand most of the modern solid state amp designs we are discussing about here, show very little harmonics. Is it slew rate, intermodulation or any other distortion product?
There must be some scientific explanation for the different sonic signatures of opamps. Any ideas?
 
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amb

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Well in this particular case it would certainly not be slew rate or intermodulation distortion (The M³'s slew rate with the good opamps are all very fast, certainly far faster than any music content, and IMD test results are vanishingly low). I've never measured a dynahi but I have no doubt that it also measures excellently in these respects. Both amps are pure class A, devoid of any crossover distortion, and both have stout output stages with very low output impedance.

The following thread explores some of this and is worth a read if you haven't already. It doesn't draw any conclusions, and I don't think there will ever be any definitive answers to these issues, but check it out FWIW.
http://www6.head-fi.org/forums/showthread.php?t=48966
 
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tyrion

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tkam, another great review. It speaks well of the amp that it compares favorably with the Dynahi. I think another comparison I would like to see is the M3 to the GS-1.
 
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Quote:

Originally Posted by tyrion
..." I think another comparison I would like to see is the M3 to the GS-1."


I agree, and I have asked for it too earlier.

Both apply extensively filtered PSU's, i.e. a M3 with STEPS, something which seems to have a considerable audio signature in general.

Perhaps in a meet soon?

BTW. My GS-1 arrived today. Straight out of the box, it is very tight in the sound with no bass extension and very narrow soundstage. It's on the burn-in rack though, should make a tasty listening experience in a couple of days I think
 
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tyrion

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Quote:

Originally Posted by Glod
I agree, and I have asked for it too earlier.

Both apply extensively filtered PSU's, i.e. a M3 with STEPS, something which seems to have a considerable audio signature in general.

Perhaps in a meet soon?

BTW. My GS-1 arrived today. Straight out of the box, it is very tight in the sound with no bass extension and very narrow soundstage. It's on the burn-in rack though, should make a tasty listening experience in a couple of days I think



Maybe Headamp and Rockhopper will send an amp each to the South Florida Meet on June 4. I promise to take good care of them.
 
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Glod

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Quote:

Originally Posted by tkam
The M3 can also drive any headphone on the planet, it very easily drove my PS-1, HP3000 and K3000.



I am curious, have you had any opportunity to test it with really high impedance phones like the HD 6xx?

My GS-1 is just in the first hours of burn-in, and it is having a handful in driving a HD650. I guess, like with the M3, those power caps need to get a fair amount of burn-in to develop the needed agility.

EDIT. Thank you for a very interesting and well written review on the M3. Sorry I didn't mention that earlier...
 
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amb

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Not speaking for tkam, but lots of people are using Senn HD600/650s with the M³. The HD600 is my own "reference" headphone, and Morsel's early DT990 is even higher-Z at 600 ohms. These combos work great too.
 
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tkam

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The highest impedance phones I tested with it are the K3000's which use the 120 ohm k1000 drivers. If someone wants to loan me a GS-1 I'd be more than happy to do a comparison
.
 
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I recently tried Rockhopper's demo M3, and was quite happy with it's sound. One thing of certain to note, it was IMO a siginificantly better match for the SA5000 than the PPA, with the rich midrange and strong bass, and a bit less of a biting edge on the highs. Much more involving, and less fatiguing experience.
 
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tkam,

Wonderful review and congrats on a great amp. I also recently had a chance to listen to the PPA V2 and M3 and posted my comments here - link - along with another friend who did the same comparison. Most of our impressions are similar to yours (it's nice to know I'm not crazy
) but I'm curious, I didn't notice a source listed in your review. Care to disclose what you were using? I found that the M3 was not nearly as source sensitive as the PPA and tended to present a nice listening experience regardless.

Nate
 
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tkam

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Thanks for the kind comments, the sources used were: Music Hall Maverick w/ underwood mods and RME 96/8 PAD.
 
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wang228

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thanks for the excellent review tkam. i'm now demoing rockhopper M3 and I generally agree with your impressisons. The warm rich sound is probably the first thing that came to mind when thinking of M3. IMO, this amp (with AD8065 and driven by a 24V elpac) when paired with my HD650 produces just the right amount of bass, with a warm rich mid and sweet blooming lower treble... it makes piano sound so good. The high is also very coherent and not piercing with (maybe maybe) a slight impression of roll off, but that could as well be the tonal charisteristic of the HD650. Overall a very pleasing amplifier. Love it... It makes my pimeta (OPA627) sound hollow/dull in comparision.
wang
 
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Quote:

Originally Posted by devwild
I recently tried Rockhopper's demo M3, and was quite happy with it's sound. One thing of certain to note, it was IMO a siginificantly better match for the SA5000 than the PPA, with the rich midrange and strong bass, and a bit less of a biting edge on the highs. Much more involving, and less fatiguing experience.


This is very encouraging - I've been looking for an amp that will be a good match for my SA5ks, and I've read several times that this amp would make a very good choice (well, the M^3 in general) ...

Anyway thanks for the great review, tkam! Your efforts are greatly appreciated, and I think I will be ordering from Rockhopper when the time comes (maybe mid-June) ... BTW, what was the turn around time on your amp?
 
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