Singlepower Square Wave Solid State Headphone Amp: Impressions & ReviewIntro
Thank you Asr for providing me with this review sample, and the opportunity to kick the tires on Singlepower's latest solid state amp. It's folks like you that make this site so great.
In general, I'm a "solid state" guy. I like the stereotypical tube sound well enough, but I've always hated the extra hassles and paranoias that come along with valves. Tube amps I've owned in the past include an Earmax, Earmax Pro, Berning MicroZOTL, Melos Gold, and Melos Maestro. I also had review samples of Ray Samuels' Stealth and Raptor. All fine amps, but only the Earmax truly exhibited the stereotypical "tube sound".
My experience with these amps left me wary of tubes. I found I resented the extra expense, the anxiety about whether this or that tube lets me hear my amp at its best, having to burn in each new tube swap for hundreds of hours, having to deal in the shadowy world of the rare tube dealer, worrying if my expensive "new" old stock tubes weren't in fact ripped out of some junkyard TV set and already completely drained, anxiety about the fact that eventually my costly "perfect" tubes will one day burn out and I may never be able to get another pair. Etc.
Of course I've read all the glowing reviews of Mikhail's tube amps, but never had the chance to hear one. It seems evident that he's a gifted engineer. So I was quite curious when Mikhail first announced he was going into the solid state amp business. I naturally jumped at the chance to get my hands on the $999 Square Wave when Asr made his generous offer.
So, here we are! Let's begin....
My System
Headphones: Sony MDR-R10.
Reference Headphone Amp: Rudistor RP010.
Source: RAM Modified Sony XA9000ES SACDP.
ICs: Virtual Dynamics Master 3.0 RCA.
Power Cords: Virtual Dynamics Nite II and Michael Wolff Bohica.
Pics!
Like the Ray Samuels HR-2, the Square Wave comes in two separate boxes-- the headamp module itself and an additional power supply.
Here is the amp itself:
Here is the separate power supply:
Here's a close-up shot of the front:
Here's a shot of the rear:
Finally, here's a shot of my whole equipment stack for scale. As you can see, the Square Wave is dwarfed by the RP010:
Build Quality / Ergonomics
Straight off the bat, let me just say that the Square Wave does not look like a $1000 amp. Unlike the $900 Ray Samuels HR-2 that comes with a custom designed and built power supply made by Ray himself, the Square Wave comes with an off-the-shelf molded plastic job. I hesitate to call it a "wall wart" because it's not a wall wart as it's too large and heavy to hang from a socket and sits separately on its own rubber footers. But it still doesn't impress if I'm being honest, especially at this price point. It reminds me of the Earmax and Earmax Pro which has a similarly disappointing-looking plastic power supply, though the Earmax's unit is roughly half the size and weight of the Singlepower's.
Like with the HR-2, the umbilical connecting the unit to the power supply of the Square Wave poses a major dilemma for how to store it in your gear stack. No matter what you do or how you set the power supply, you'll always end up with a mildly unsisghtly tangle of wires clearly visible on your shelf. Speaking of wires, unlike the HR-2, the power cord on the Square Wave is
not detachable. This means you can't use aftermarket power cords with the Singlepower. As a big believer in aftermarket cords and someone who's done
a lot of research on them in order to find the best, being unable to use them is very frustrating.
The headamp unit of the Square Wave has a smokey plastic front and rear fascia that kinda-sorta allows you to see inside the unit if you peer inside with a bright flashlight. If Mikhail really wanted to let us see what's inside, he should have simply used the clear plastic on the top of the unit. Personally, I worry about the clear plastic picking up scratches, so I'd be happier all around with a pure metal case.
The volume knob also does not inspire much confidence. It's dinky, plastic, and ever so slightly wobbly to the touch. This would be fine for a much cheaper portable amp, but not on a home amp like this, especially when you consider the $900 Ray Samuels HR-2 uses a much bigger and more secure knob with a nice, firm action. So, it surely can be done at this price point.
Also like the HR-2, you will notice there's something missing from the square wave-- no on/off switch. It's always on once you plug it in. I understand this may be done in the name of audiophile purity, but I was never comfortable with this for the several years I owned the HR-2. I live in an area with lots of electrical storms, and I'd be concerned about damage. Yes, I suppose all I have to do is unplug the unit, but I'd prefer a simple on/off switch, YMMV.
Finally,
this unit is not wired correctly. In the pic of the rear of the unit, you'll see two sets of inputs with white on top of red. As it turns out, you have to plug your cables into both of the white inputs in order to get sound in both channels. The red inputs don't seem to function. However, without proper white and red labeling of the inputs,
I can't be sure I have the channels set correctly!
Overall, the Square Wave does not impress one physically as a $1000 headamp. Honestly I would expect a little more and have received a little more from other vendors at this price point.
But all that can very easily be forgiven if the Square Wave performs well above its price tag. So does it?
Listening Impressions Day 1
So, I'm presented with a bit of a dilemma. My ears are now spoiled by having moved up into the world of the truly high end headphone amp. First with the remarkable Rudistor RPX-33 ($1800), and now the Rudistor RP010 ($3200).
There's almost no way that a $1000 amp could be expected to deliver comparable performance, and clearly, right away I can tell the Square Wave does not. But that's not at all a fair comparison anyway. It would be an uphill struggle to find enough nice things to say about the Square Wave in comparison to the much more costly Rudistors. So I have to re-adjust and take the amp on its own terms at its own price point. This is a good lesson and exercise for me as a reviewer.
A more relevant comparison is to pit the Singlepower against the similarly priced Ray Samuels HR-2. Now, I no longer have this fine product to do direct A/B comparisons, so I have to work from memory, which I recognize can be a tricky thing. But I did own the HR-2 for several years and knew it like the back of my hand; I believe it's sonic signature is imprinted in my memory. I loved that amp, even better than Ray's more expesnive tube amps, and happily stuck with it for a long time.
Anyway, please don't read these initial impressions as being overly negative. These are the observations of someone now accustomed to a $3200 amp.
I also don't know how many hours of burn-in this unit has, but I will try to clarify that with its owner and will update.
Observations
1. Overall tone is warm. But it's not especially rich or full or tubey, erring more on the thin, dry side. But because the edges are so soft, it doesn't have any typical solid-state "etch" to it of the kind that makes sounds seem sharply "outlined" or "digital". It's a very "analog" sounding amp, maybe too much so. Because it's sort of "soft-focus", any sense of solid-state granularity or grainy-ness is pleasantly smeared away, making the sound as smooooth as a baby's behind.
2. Punchy, "active" sound. Fast and nimble. Seems to have adequate power for the notoriously power-hungry R10s. Should easily power any other headphone.
3. Highs are clearly rolled at the very extreme, yet what is there is a bit overly excitable and "projecting" at times (not always). They can kind of leap forward and stab the ear a little bit. It's like there's a little bit of overshoot or extra topspin on the mid-treble. I find this a bit distracting and fatiguing.
4. Bass is one-note, but reasonably firm, warm and full of mid-bass bloom. No real deep bass is present. Overall, the amp is slightly rolled at both frequency extremes.
5. Soundstage is relatively compact, but coherent. However, it lacks depth.
6. Images are kind of soft-focus, with a bit of gauze or vaseline on the lens, lending it a bit of that fuzzy 70's-style "glow" around the edges you see in old family portraits at the Sears studio.
7. Background is not completely black, and this is not nit-picking, as at this price-point you can buy a unit that delivers Ray Samuels' famous "blackground".
8. Because the sound is not especially crisp, individual instruments are not clearly dilineated and lack a sense of air and dimensionality. You are sitting in a warm-ish soup of sounds and instruments that blend together, albeit pleasantly. You never get the feeling you could reach out and "touch" the musicians. The Square Wave is better at presenting the overall picture than in defining the individual elements that make it up.
9. I would say the Square Wave is not an especially "transparent" amp. It sounds a bit same-y on eveything, applying its own sonic pallette to everything it paints. Warm and mostly pleasant except for the occasional mid-treble spike. If one likes this particular sound, you are in luck because it will apply it to everything in your music collection.
Summary
It's possible that this review sample is not fully burned in, but I know that Asr wrote a review of this very model on Stereo Mojo, so I am assuming he's fully run it in.
I'm not especially taken with the build quality of this amp. The fact that this sample isn't wired to accept white-to-white and red-to-red cables is really concerning to me. I know this isn't a mass-produced product from Sony, but IMHO, this "quirk" of its construction is unprofessional. Mikhail should have caught this.
Sound quality is pretty good, if you like its basic tone. If it weren't for the occasional mid-treble spike, this amp would easily appeal to those who like audio products that do everything they can to not offend. The Square Wave is clearly rolled at both frequency extremes, with a warm, soft-focus sound that will handily disguise most upstream flaws.
That's either its chief appeal or its major flaw. If you have a badly-behaved source, the Square Wave will help homogenize and tame the sound for the most part. Should be a boon for people who use their computer as their source. But what if you have a high-quality stand-alone player? At this point, I'm not convinced it will suffice for you.
My mind is still open, and I will burn this unit in for the duration of the time I have, but I'm not optimistic my opinion will change. IMHO, the incredibly well-built Ray Samuels HR-2 is a much better value with superior sound quality over the Singlepower Square Wave.
More impressions to follow...
2nd Impressions-- Day 8
So, I've been burning in the Square Wave 24/7 since my last post. That puts roughly 200 more hours on it, though it's still not clear exactly how many hours the unit had on it to begin with.
I have not listened to the Square Wave in the intervening 8 days, so I came again to it fresh. Has it changed, or did my perception change?
In a word, "no". I think I pretty much nailed it (if I do say so myself
) in my initial impressions. After another dozen rounds of A/B-ing again my Rudistor RP010, I found myself writing down pretty much the exact same comments I already made.
While I was not over-whelmed by it, the Square Wave is far from a "bad" product. It has many positives:
1. Relatively grainless/clean, natural "analog" sound with a pleasant warm tone. Getting a nice tone out a piece of solid state is no small thing, so big-time kudos to Mikhail here. I would say the friendly tone of the Square Wave is it chief selling point. I think many people on this board overlook tone as an aspect of the gear they buy and review, when it's really THE most critical feature after which nothing else really matters. Who cares how low the bass goes if the tone is artificial, mechanical, or "fake". Maybe we just take it for granted, but we shouldn't.
2. Speaking of bass, the Square Wave's is solid and punchy in the mid-bass (if a bit loose). There is noticeably more mid-bass on the Square Wave than on my RP010, but again bottom octave is missing. Which unit is right about the correct proportion of mid-bass? The Square Wave is just a *hair* intrusive to me with its thick throbbing mid-bass, but that's purely a matter of taste. It's also a pity that the Singlepower's bass is not as articulate, being relatively one-note (albeit a pleasant warm note).
That said, IMHO, the Square Wave has some down-sides, and not just relative to my RP010 but to comparable units at its price point (i.e. Ray Samuels HR-2):
1. There is this annoying mid-treble spike that I just can't escape. It's such a revelation going from my RP010 back to the Square Wave. The top-end treble extension disappears, replaced by a slightly edgy, intrusive mid-treble that's a little "fizzy" (for lack of a better term). The RP010 has so much more extension and presence up top, yet it's so easy on the ears. I guess that's one of the things you get with a truly high-end amp like the Rudistor. On the Square Wave, cymbals and other high tones have a tendency to sizzle and splash, and this is fatiguing over time. The Ray Samuels HR-2 with stock AD797 op-amps never gave me this same problem.
2. While the Square Wave succeeds handily with the fundamentals of tone, IMHO it falls short on the other audiophile niceties we expect. Things like soundstage, blackness of background, air, and imaging. I think the chief culprit is the lack of clearly defined edges around individual sounds. Sounds get softer and less focused at the front and rear ends. This makes everything seem slightly smeared together, soup-y and non-specific. The soundstage is quite flat from front to back, there's no depth. It doesn't throw a clear hi-rez image like some other amps I've owned. Things aren't easily locatable in the soundstage, they can kind of drift around ghost-like. When you try to focus all your attention on one performer or one instrument, you can never quite get a firm grip on it, it sort of slips away from you like a wet wriggly fish. The lack of complete top-end extension also means there is a noticeable lack of "air" around the instruments and performers, leading to a moderately closed-in, self-contained sound.
Conclusion
Ultimately, I can't recommend the Singlepower Square Wave when there is a nearly identically priced product on the market that out-performs it in 80% of all other areas, the Ray Samuels HR-2. The obvious question arises, is it merely a matter of taste between the two with me simply picking the other amp? I don't think so. I would guess 80% of people who A/Bed the two amps would end up going home with the HR-2. I think we are talking about pure performance rather than taste.
In terms of build quality, however, it is indisputable that the HR-2 beats the Square Wave hands down. The HR-2 makes the Square Wave look like a $400 amp (at most). The fact that the jacks on the rear aren't wired correctly on this sample epitomizes the standard of build on display here.
It will be very interesting to hear from the other reviewers to see what they think with their amp history and perspective. I may end up being an outlier. They may tell you it's the greatest thing since sliced bread. We'll see...
