The Authoritative and Potent Violectric V281 Headphone Amplifier

INTRODUCTION
Roughly three years ago I reviewed a pair of headphone amplifiers from a German firm called Lake People. I quite liked both models and to this day they remain very strong recommendations in their respective price categories. The Lake People gear is geared more towards studio applications, meaning less creature comforts and practically zero eye candy—depending on your definition of course...I happen to like the black box look.

Lake People also has a division specifically for audiophiles and their unique needs. Dubbed Violectric, it takes those pro-audio sensibilities and ratchets them up a few notches. The result is a range of amplifiers which formerly culminated in the $1,069 HPA V200. The V200 is practically legendary these days—seems like nearly everyone has heard one at some point, and I know many people who use it as a reference. I did the same for several years and might still be doing so to this day were it not for the topic of this review: the Violectric V281. At $2,299 the V281 is serious business in every sense of the word, with the looks, features, and most importantly, sound, befitting a world class device.

Frankly, I'm a little late to the party here. Violectric set me up with a V281 review unit some months ago, and I've been using it extensively for various other product evaluations. It's served me so faithfully, without drawing attention to itself, that I found myself slipping on the actual review. I also decided early on that I simply must have one of my own for my reference system—I arranged to buy my own unit, in a different configuration (which I'll discuss shortly), but kept the review loaner around so as to compare the sonic impact of certain upgrades. So, I feel apologies are in order both to the folks at Violectric as well as the many readers who have patiently waited to read this review. I get emails and HeadFi messages on a regular basis asking when it might be complete. The time has finally come, and the V281 certainly deserves the attention.

Violectric_V281_Photo_SilverBlack

DESIGN
The V281 is by far the largest piece of equipment Violectric has done. Prior amps including the V200 all used the same compact form factor which made for very easy placement and system integration at the expense of some flexibility. There was only so much room for inputs and outputs, so the devices weren't the most suitable for complex systems. Violectric sought to counter that by offering a wide range of gear in matching compact enclosures—V600 phono stage, V800 DAC, V630 preamp, and of course the various headphone amps. The V281 has the same width (five inches) but is exactly twice as tall as the other units. So V800 DAC and V600 phono stage stacked together would perfectly match a V281 in height and width, though not in depth where the V281 is about three inches deeper. Think "shoe box" and you're on the right track.

Violectric_V281_Photo_RearPanel

This extra room allows for a broader feature set than ever before. The V281 is equipped with inputs and outputs in both RCA and XLR format along with the very useful pre-gain switches, and there's room on board for an optional DAC module. The DAC adds $240 to the bottom line and comes in three flavors: Asynchronous USB, Coaxial, or Optical, all of which boast 24-bit/192kHz capabilities. Up front we get a 4-pin XLR output along with a pair of 1/4" jacks, balance control, a humongous volume knob, and individual buttons for input and output selection. The device also acts as a high quality preamp, allows for routing of any input through any output, and can independently activate headphone out, line out, or both together. It's really quite versatile and should be able to insert into just about any system without much trouble.

Build quality is phenomenal. These are hand assembled at Lake People headquarters in Konstanz Germany with stereotypical Teutonic attention to detail. Even in things as simple as pressing the power button or cranking that huge volume knob, one can feel the quality at hand. It just feels right. I've had dozens of DACs, amps, and other gear come through here in the past year alone and I have to say the V281 is right up there with the very best. The Nextel coated chassis is somewhat unique and the grey color fits in whether one chooses the silver or the black faceplate. Did I mention this thing was fairly customizable? The footers can be had in silver, black, or gold—factor in the various DAC options and the several optional volume control upgrades, and there are quite a few possibilities to be sorted through.

Inside that lovely chassis, the V281 is a beast. Violectric took their already quite potent V200 concept—a discrete design using 8 output transistors per channel—tweaked it for improved performance, and then essentially doubled it, along with beefing up the power supply. We're talking a pair of large toroidal transformers flanked by 36,000 uF worth of capacitance. When using the XLR output this is basically like having an improved V200 driving each channel of your headphones. This makes for some very serious juice. Max output is 5600mW per channel into 100 ohm loads which corresponds almost perfectly with Audeze's LCD-3 Fazor. For higher impedance headphones, V281 can swing over 40 volts into a 600 ohm load, which is head and shoulders above most others. Competitors such as the Bryston BHA-1 or Schiit's Mjolnir, both powerful amps in their own right, do less than half that. Of course, power means nothing if it isn't of utmost quality, and Violectric certainly isn't just going for big numbers alone. Their strategy remains the same as always—high damping factor due to very low output impedance (.1 ohm single ended, .2 ohm balanced), high current due to powerful output stage, low noise due to low internal gain, and very high output voltage. The formula is unchanged from the lowest Violectric model to the highest—it just gets more extreme as you move up the range, culminating in the V281.

It might be worth noting that Violectric also has another new model called V220, for those who aren't interested in recabling their headphones in the 4-pin XLR termination. The V220 ($1,669) sits between V200 and V281—it has the upgraded V200 circuit (but only one, rather than one for each channel) while offering increased inputs and options like the V281. My first thought is that it makes sense to either save money by using the still excellent V200 or else go all out with the flagship V281. But I suppose intermediate options are always nice to have. Then again, someone using the device primarily as a preamp in a nice speaker setup, with headphone use as a secondary function, might find the V220 just the ticket. More casual headphone users won't be as likely to have balanced headphones, and the expanded inputs/outputs over the V200 would certainly come in handy. So perhaps the V220 makes more sense than I initially thought.

Of course, expensive gear must do a lot to justify such a high price. At over $2k, Violectric's flagship belongs to an exclusive club with only handful of members. A select few of these expensive offerings do in fact justify the dough in my book. But there are quite a few others which I don't consider worth the money at all. Is the big Violectric worth the increase over the already stellar V200? Let's find out....

COMPANY INFO
LAKE PEOPLE electronic GmbH
Turmstrasse 7a
78467 Konstanz
Germany
+49(0)7531-73678
ARTICLE CONTENTS

COMMENTS
XVampireX's picture

Great review.

Any chance for an Audio-gd review by you or Tyll?

Innerfidelity has never done 1 review of an audio-gd product, seems fishy.

John Grandberg's picture

Not sure what to make of your "fishy" implication. What do you suspect is happening? But, to answer the accusation: I have a generally positive view of Audio GD. I reviewed their Reference 7 DAC at HeadFi some years back (when it was first released), and quite enjoyed it. I haven't spent any meaningful time with their newer gear.

Several issues have prevented me from seeking something to review. The main thing is how their lineup changes so rapidly. By the time I have a review unit shipped, do my listening, write it up, and wait for my spot in the publishing schedule, there's a good chance a new model will be out to replace the thing I reviewed. That's obviously not desirable from our standpoint - we want to keep our reviews relevant, and covering something that is no longer available is not the best approach. Not to mention their rapid pace has always made me somewhat skeptical... how much time is spent designing each one, when a replacement is always far behind? I know I'm not the only one to voice this objection.

Of lesser concern are build and reliability issues, language barriers, the massive size of the higher end models, the rather confusing naming conventions.... but the ever changing lineup is really the key issue.

That said, the Master series has proven to have staying power (for Audio GD products at least), so perhaps things are changing a bit. I will consider reviewing something from them if I spot one looking noteworthy.

cspirou's picture

Even more surprising to me is that there isn't a single review of a Schiit audio product. Considering how popular they are I would expect a write up of one of their amps or DACs somewhere. I see the Schiit ad all the time when I visit innerfidelity so maybe its a conflict of interest? Although I doubt that because I see an ad for Audeze as well and they have plenty of reviews.

John Grandberg's picture
We've actually given quite a bit of coverage to Schiit. Bifrost was favorably reviewed. "How Schiit happened" was highlighted. Modi and Magni were named "showstoppers" at T.H.E. Show 2013. Bifrost appeared in one of our Holiday Gift Guides. This in addition to plenty of other show coverage. And Tyll intends to cover Ragnarok soon enough. So no, we aren't avoiding them at all, I think most of us hold them in high esteem.
cspirou's picture

I missed the Bifrost review somehow but I found it. Although there is no review on their amps like you have done for the Violectric. I wasn't really insisting that you never mentioned Schiit but show reports aren't really reviews.

I look forward to the Ragnarok review though.

John Grandberg's picture

We've actually discussed this internally, and at one point had an amp review in the works (Mjolnir maybe?) but review loaners were hard to come by at the time, so it eventually fell by the wayside.

But you're right, we could do a better job on this, as Schiit deserves all the attention they get.

Impulse's picture

The one Schiit review on the site was also by Guttenberg... No offense to him, but I don't exactly come to Innerfidelity for his occasional guest articles (I can go to this CNet blog for that anyway).

Just saying, I come to InnerFidelity to read your reviews, Tyll's, joker's, etc. I'd welcome any and all reviews of more affordable amps/DACs tbh.

Bob Katz's picture

So, for low impedance cans, is it the headroom that makes it sound better? We know you're only using a fraction of that 5 watts. I ask facetiously because I believe in headroom having an effect. Why not match the output voltage of the Violetric with that of the $200 O2 amplifier (600 mw capable) and feed them both from the same external DAC. Then A/B compare the two. Inquiring minds want to know. In my upcoming review of mid-priced cans I intend to do the same with the Burson versus the O2, but I need to find a neutral killer amp (class D?) that won't blow my ears as well.

John Grandberg's picture

I tend to agree with you - headroom is important, probably more so than most people think. That may very well play into the subtle differences I hear between various well-designed amps.

Speaker designer Jim Salk once relayed to me a story about testing amplifiers. They set up both average power meters (RMS) and peak-reading meters and monitored power levels while playing music. While the RMS meters showed in the 5 to 8 watt range, the other meters showed peaks in the 200-250 watt range during instantaneous transients such as drum hits. So, while on average 5-8 watts was sufficient, the best possible performance was achieved with a far more powerful amplifier.

This seems to line up well with my subjective experience. A nice amp delivering doing even 100 mW can sound excellent most of the time. However, with some headphones and some music, a far more powerful amplifier pays dividends.

I'm glad we are are somewhat on the same page here. I look forward to reading the results of your upcoming experiment.

Bob Katz's picture

Dear John: The hardest part will be the "all things being equal" department. I could test my Burson and O2 at matched gain, but they obviously sound so different anyway how do I know the sonic improvement of the Burson is due to its headroom? So I would like to hear a more powerful but more neutral amp than the Burson. The highest peak to RMS ratio that I have ever measured is with some of my own audiophile recordings, and that could be as much as 24 dB.

I really should compare this in volts, but having the figures in my head, if the maximum wattage of the O2 is 0.650 and the Vioectric is 5 watts, that's a ratio of only 9 dB. OK, let's be more practical. Audeze LCD-X maximum power rating is 15 W for 200 ms. Let's not exceed that. It produces 103 dB with 1 mW. With a nominal RMS forte level of 83 dB, that would be 0.01 mW average power. 24 dB above that would be 2.5 watts. So 2.5 watts rating is probably enough to handle the most extreme transient peaks and not go deaf.

Bob Katz's picture

I didn't get my milliwatts and watts right. And there's no way to revise a post in this dang forum. I'll be back with the correct numbers after my afternoon run!

Bob Katz's picture

OK, so since the LCD-X are rated at 103 dB with 1 mW that's already the peak level you would ever want to drive within a few dB. So even a 1 mW amp has the headroom. The question that has to be asked is: Is headroom beyond, say, 1 watt in an amp at all meaningful when 1 watt is already 143 dB! So the numbers are saying enough is enough. It would be nice to make a controlled experiment and for me matching up the $200 O2 with the $2200 Violectric at matched voltages would be a very interesting test. As is my experience with subtle differences, most of them will dissolve when the loudness is matched and what's left will not be 10 times the improvement or whatever. But as usual, prices go up exponentially for the tiniest perceived improvement. That's the audiophile world.

zobel's picture

A $150.00 portable amp vs a $2300.00 stationary unit is a little like a Chevy vs a Lamborghini, but why not? I think they both will get you there, but the O2 will make music during the trip and at home, while the Lake People unit will only play for you while you sit in you stationary chair. I'm happy to see this comparison, and look forward to reading what you find out in the Burson vs O2. Choice of cans will be crucial there.

xnor's picture

If you use an O2 then keep in mind that high gain and high input levels can clip the signal regardless of volume control position.
Max gain = 7/Vsource, all in RMS, e.g. 3.5x with a CDP that outputs 2V.

Secondly, you need to level match with your headphones connected else you will ignore output impedance - load interaction.
If you want to do this properly then levels should be matched really carefully.

As killer amp, it's probably best to use a clean, low power (25W into 8 ohm should do), class AB speaker amp.

johthor's picture

This is a really great review. I have had the V800/V200 stack for about 6 months and really thought I was at a place where I no longer needed to upgrade. Now after reading this really superlative review I am not so sure about not needing to upgrade anymore. One thing I know for sure there will always be a Violectric component to my listening equipment

John Grandberg's picture

I spent several years enjoying the V800/V200 combo. It is EXCELLENT! The mere fact that something better exists, should not at all diminish your enjoyment of what you already have. You certainly don't NEED to update anything.

johthor's picture

Thank you for the response, John. I most certainly agree with you and will be quite happy with what I have until, and if, I decide to give the balanced route a try.

Bob Katz's picture

To repeat: I really want to test the contention that more power sounds better, at equal matched loudness. Can you at least do an informal (non-blind) test. Measure and match the voltages of the O2 (a very good sounding inexpensive amp) with the Violectric and let us all know what you think. Thanks!

John Grandberg's picture
I just boxed up the Violectric and will be shipping it over to Tyll as soon as he is back from vacation. I'm sure he would be interested in giving that a go.
Bob Katz's picture

I always test the losses of an amp under load. Most of the amps with low enough source impedances don't vary more than 0.1 dB under 20 ohm load versus high impedance. I'm not going to do the load test with the actual headphones. It'll be done with a load resistor. Too much money to lose if an accident happens.

My idea of a killer amp would not be Class AB. It would be fully Class A or possibly Class D.

xnor's picture

I guess that level-matching technique works okay if your dummy load matches the nominal impedance of your headphones.
A 0.1 dB deviation would be bad since your "profession is to make 0.1 dB decisions and to discern small differences". :P

I thought you referred to "killer" as in an amp with so much power that it could destroy any headphone in an instant, i.e. a power amp. :D
You know that AB does run in class A for typically up to a few watts, right? But sure, class A is fine as well.

I wouldn't choose a class D power amp due to output filter <-> headphone load interaction. These things are designed e.g. for 8 ohm loads, so you'd probably need to add such a resistor in parallel or measure the loaded frequency response to be sure.

Bob Katz's picture

Xnor, to answer both your comments: The problem with "reply" in this forum is that the forum software has no way to search for "unread posts" so it's easy to miss posts. So it's tempting to put a newest post at the bottom of the list. I know i'm going to miss a new post when replying within the stream because the software forces you to keep reading and re-reading every long thread.

Next, well, for me as is obvious by your :D sign is that "killer amp" would be one that sounds better than anything else. The hard part will be to determine why and make sure we're not fooling ourselves.

As far as output filter load interaction, you're talking about ancient Class D or those cheap chip amps. The best current-day Class D amps can deliver amazing power to most any load. Take a good look at the Hypex NCore spec sheets. Anyway, I had a long talk today with Bruno Putzeys, developer of the Hypex, and while there is no current-day Hypex headphone amp, maybe someday there will be, and it could become then the killer headphone amp if someone designs a discrete, 5 to 10 watt model. We shall see. Those little Class D chips do not excite me, but the discrete Hypex have changed the world.

However, Bruno recommended (and when Bruno talks, people listen) a small Class A amp for cans. I would concur. Basically there's no point in doing Class D for small signals. While it's true that Class AB amps operate in Class A for small signals, my experiences with Class A in loudspeakers have turned my head and I'll take Class A over AB for loudspeakers any day; their purity of tone just turns me on. And that was the case until Hypex and some competitors came along. Class D, however, has converted me and I have 5600 total watts of Class D power driving my 5.1 system. I no longer have any Krells or similar eating up my bankbook, electric bill or heating my Florida studio. And I don't miss the Krell now that the best of Class D has proved its worth.

Since pure Class A (when would it be "impure"? I guess if it turned into Class AB at some higher wattage) is reasonably simple to engineer for a small signal amplifier there's no reason to make a 5, 10 or 20 watt amp with any other topology, if you like Class A sound as much as I do. And it won't draw so much as to kill your kilowatt-hour budget.

cspirou's picture

If you are willing to build it I think a firstwatt F5 would be a good amp to try. Very low distortion and noise at 2x25w class A into 8 ohms which should translate into 6 watts at 32 ohms.

My other choice would be the NAD D3020. It is an ultra low distortion class D amp based on Hypex technology. Something built with a couple NC400 modules would be even better!

Bob Katz's picture

You just blew my mind. I have no idea why I didn't think of driving headphones directly from the speaker terminals of a D3020! I couldn't see the forest for the trees so many thanks for your suggestion. The NAD also includes a DAC for that price so it's a very special piece of kit.

I do wonder if the sensitive LCD-X will reveal any noise, however from the loudspeaker outputs. I can ask Bruno. The NAD price is amazingly good and it has that magic Hypex inside. If I could afford the price and the time I would build a Firstwatt. I've seen already-built Firstwatts going for about $2200 so someone should shoot that out against the Violectric! Again many thanks for that suggestion. And again the question arises whether sensitive headphones would pick up the noise of a Firstwatt as well. Have to settle that question before venturing into a 25 wpc amp, whether it's Class D or Class A.

Bob Katz's picture

Before buying that I would have to determine several things:

1) if it's ok to common the black terminals together or if I have to run the headphones balanced (floating common)
2) If the noise at the loudspeaker terminals is audible through the headphones. That would be a no-no
3) If the gain of the 3020 is so high that it would have to be modified inside.

Quite a few concerns! At least with the Pass amp you get a full schematic.

Bob Katz's picture

I just heard back from Bruno who said that very bad things could occur with a D3020 if making a common of the black terminals so I definitely would have to run my headphones without a common.

No answer yet on the gain structure of the 3020 and if I purchase it I would want to get a money back guarantee in case it's too noisy for sensitive phones.

The review and the NAD manual seem to imply that the built-in headphone jack of the D3020 is NOT derived from the class D amp and since it is an unbalanced jack that would be a clincher. A "dedicated headphone preamp" is described somewhere in a review or the manual.

Next I have to check with the wife to see if another $500 for "fun audio stuff" would even be permitted in our current financial times.

Bob Katz's picture

Similar question if using a first watt's speaker outputs: Would it blow up if using unbalanced headphones and common connecting the low speaker terminals?

cspirou's picture

At least for the F5 amp it shouldn't be an issue. According to the schematic the negative speaker terminal goes to ground and wouldn't really hurt the headphones. There are a couple fully balanced builds and you need more caution with those.

Looking up the Hypex amp modules it looks like the speaker outputs are not differential outputs and the negative terminal goes to ground as well. Although the NAD amp has a headphone jack which might be driven by the speaker outputs instead of a separate circuit.

xnor's picture

The best current-day Class D amps can deliver amazing power to most any load.

I didn't say otherwise. I said there can be output filter <-> load impedance interactions with some class D amps.
But with the Hypex designs this appears to be indeed of no concern.

The important thing to watch out for is noise in power amps. Even super-duper class A heaters will usually produce an audible noise floor if you directly drive headphones.

cspirou's picture

Just looked up the numbers for the amps I mentioned. F5 is around 100µV. The O2 has a noise level of about 3µV so the F5 is certainly much more noisy then headphone amp. Of course this is a major issue with driving IEMs and sensitive headphones. With high impedance headphones and planar magnetics the noise might not be an issue. There are some Firstwatt amps that have noise level from 30-50µV which is about the level of a tube amp and a bit more acceptable.

Assuming the D3020 is similar to other hypex amps, the noise should be about 30µV which is also acceptable. Note that the NAD amp has a headphone jack which is limited to about 6V RMS. I don't know if this is coupled with the speaker outputs or if it has a separate amp to drive the headphones. Either way, its worth checking to see.

Bob Katz's picture

Where did you get the 100 microvolt noise spec on the F5? These being unweighted figures probably make it tough to compare but on this page www.firstwatt.com/f5.html Nelson says it's got about 60 microvolts of noise. Don't know the bandwidth that's measured, but if it's wide band that's QUIET. The Audeze LCD-X produce 103 dB SPL with 1 mW/20 ohm, which is 0.1414 volts. 60 microvolts is 67.4 dB below that. So 103 -67 = 35 dB SPL. Which may or may not be audible in a quiet room, depending on the spectrum of the F5 noise.

cspirou's picture

I got it from the product page comparing all the amps.

http://www.firstwatt.com/prod.html

The page probably needs to be updated.

zobel's picture

Everyone knows that 1 dB is the smallest change in loudness humans can normally discern. Bob probably got his decimal point off again.
We should be kind though, he is aging like the rest of us, and forgets things, just like the rest of us, even, for example, what is bass, midrange, and treble in Hz. Forgiven.

xnor's picture

Nope, 1 dB level differences can be heard. Depending on the situation even fractions of a dB can be heard.

Fastl and Zwicker document 0.5 dB for random white noise at 70 dB SPL, or just 0.2 dB for a 1 kHz tone at 80 dB SPL.

There is a reason for the recommended 0.1 dB level matching in ABX tests.

Bob Katz's picture

This is the one and only time I will probably agree with Xnor. If you want to compare two amplifiers, you must match them to 0.1 dB or better. I guess the poster who mentioned the 1 dB never read my blog here :-)

xnor's picture

Oh and please use the reply button to reply.

zobel's picture

Has it ever been shown in blind tests that people, while listening to music can distinguish overall loudness level differences under 1dB? That is what I was wondering. No doubt for measurement purposes the 0.1dB matching accuracy is a good, probably necessary thing to achieve. I can't imagine a person having to make 0.1dB decisions by ear every day, with music or test signals. I think I would be a basket case, if I'm not already.

xnor's picture

Yes, smaller differences in volume than 1 dB have been detected.

But the claim about 0.1dB is indeed ridiculous.

Bob Katz's picture

Gilmore Dynalo looks like the bees knees and would give a run for the money of any commercial discrete Class A amp. If I build it from parts it would be a big money saver, but do I have the time and the energy it requires to find all the parts from a B.O.M. and then align it, match transistors and then debug it if it doesn't work first time. Egad.... So tempting.

The Twisted Pear Virtus is much closer to ready to go, buy the kit, power supply, add a case, 1/4" connector, input pot, input connectors and it should deliver a little more than a watt. The chip has a good reputation. In the end would it sound better than my discrete O2? Would it ever come up to the quality of a Dynalo? Would it prove anything about headroom?

Bob Katz's picture

I think the Dynalo build looks very serious if there's no kit. But the AMB M3 is cool because AMB provides such a nice helping hand, very nice step-by-step instructions. What a nice company, AMB! I calculate >2.5 wpc with the M3 maxed out with the 40 volt power supply into 20 ohms. And a lot cheaper than a Violectric. I can handle this! It's now on my list for rainy days in Florida.

xnor's picture

I wouldn't trust any of amb's numbers, see amb mini3 review.
Also see virtual grounds and 3 channel amps.

Bob Katz's picture

AMB measured their equipment using a Motu Firewire interface and made it clear that a lot of the noise and distortion that they found was latent in the interface. I use a Prism Lyra-2, which is about as close to the state of the art in converters as you can get, an order of magnitude better numbers and would be a better interface to measure with. AV guy did not find giant differences between the AMB "specs" and his own specs that could not be explained either by his use of different load resistors than they used, or the latent noise/distortion of his interface. Didn't he use an Audio Precision, after all?

As for the virtual ground thingy, AV guy may be right, but it's not as if the AMB M3 is suffering because of his insistence on that particular technology. It didn't get that reputation for that reason. One would have to build two otherwise identical M3's, with equivalent power supply quality, one with a bipolar and one with the virtual ground, and carefully A/B them in order to truly answer that question.

xnor's picture

amb's numbers are indeed very far off, even the simple math as discussed in his forum was off. This has nothing to do with the audio interface used.

Besides, the numbers are too good, not too bad. NwAv suspected that some of these tests were done completely unloaded - and he was right. Another user confirmed this by doing an unloaded test with similar result. I'm not sure if you can still find it, because these topics were closed or deleted and people silenced.

IIRC one of amb's defenses was that dynamic music is a far easier load than test signals, which of course doesn't explain the wrong math and fake "loaded" test results.

Anyway, I'm not saying the M3 is bad, just to be careful what this guy is selling.

woobanger's picture

I've been a happy use of the Auralic Taurus the past couple of years as my reference SS amp but have had the itch to replace with the V281 the past few months based on other reviews and a couple of short auditions at a local retailer.

My urge to upgrade had been in check recently simply due to being occupied with other things, but your review is reigniting the fire so to speak as I know you thought very highly of the Taurus and it seems you prefer the Violectric.

One other recent contender for the spot in my rack as the reference SS amp is the Moon Neo 430HA which I have heard excellent things about. I haven't had a chance to audition yet, but I'm a big fan of Sim Audio amplifiers and a sucker for power so I can only imagine it will be a positive experience.

Have you had a chance to hear the 430HA and if so, any thoughts in comparison to the Taurus or the V281?

John Grandberg's picture
Thank you for the relevant post. I don't have experience with the 430HA but Tyll has been enjoying it for a bit. I'll be shipping the V281 his way, so expect comparisons from him soon enough (along with several other high-end alternatives).
SonicSavourIF's picture

Nice review, poetic and all, but alas, non blind reviews, what can they tell you in the first place?

I really appreciate Bob's suggestion of doing a level matched blind comparision of the O2 versus the Violectric amp (maybe against the other amps, too?). Come on people, we know how much our brains can fool us. I'm really getting tired of reading long raving reviews on gear, when every time I am wondering, why doesn't any of those golden ear reviewers take the step of just comparing blindly?
If I saw the pricetags and the features and build quality of these super expensive amps, I would immediatelly be driven to think they can only sound better than an inexpensive amp like the O2. But do they really? Why is everybody so scared of really ansering that question.

Afterwards, you can still prefer the more expensive amps for ther fearure richness and build quality expensiveness and whatnot, so what do you acutally loose? Scientifically speaking, it is simply an interesting question to explore our perception, our ability to hear (or not to hear) a bit more thoroghly.

It would be so awesome to gain some reliable statistically significant blind test data with people that are really trained to listen to details (like Bob for example). It could be a huge fun to check the audability of amps that measure within a certain range of specs and for the fun of it, why not also include amps that don't? Just to see how much certain specs really matter?

cspirou's picture

Blind tests are a gigantic pain to run and I can live without those as far as regular reviewing goes, especially with anything involving headphones. Maybe specialized one-off articles where they get a bunch of reviewers in the same room but otherwise its a distraction.

What I would really like are measurements like we see with the headphone reviews. I understand that Tyll is getting close to getting his measurement setup up and running.

Bob Katz's picture

Actually I did not advocate a blind test for the amp comparison unless it was conducted and supervised by a psychoacoustician experienced in performing blind tests. There is no such thing as an informal blind test. I personally know two of the world's experts on blind testing and they can support that contention: Only the most formal and regulated blind tests under the BS.1116-3 protocol with proper training and proper choice of sources have any chance of succeeding on subtle variances.

With subtle differences such as we are likely to find and matched levels, a fully blind test on an ampifier is more than likely to come out statistically invalid and not satisfy anyone. We are a long ways from being able to make a funded (figure $100,000) blind test on the audibility of something even as simple as harmonic distortion.

So I'm fine with a level matched nonblind comparison. It's as good as it's going to get without taking years off and doing it blind.

xnor's picture

Repeating this doesn't make it right.

First of all: all audio engineers I know have done informal blind tests. You match the volume and then you either have a friend switch, or you use a switch box, or switch by software.

What you are talking about is a formal test that is conducted so rigorously, that it would be accepted for publication in a scientific journal. Nobody is asking for that here.

In previous comments I explained that just level matching and doing a couple of blinded back and forth switches is an experience that every reviewer should make - and I think such a procedure should be included in any comparative review.

Even a more formal test (something you could put into a review without being laughed at) is not that hard to do if you know what you're doing.

Saying it would take years is just a cheap excuse, because it most likely only takes a small fraction of the time you spend on sighted comparisons.

Bob Katz's picture

Xnor, sorry, you are wrong. An informal blind test is an improperly done blind test and is more than likely to produce null results. End of discussion. I can't waste my time talking about blind tests with non-experts.

xnor's picture

Then why do you keep talking about it? :D
Feel free to participate in blind testing discussions on hydrogenaudio -- let's see how much of an 'expert' you are..

Also saying "you are wrong" and then making a factually wrong statement doesn't help your anti-blind testing case.

If you don't do the level matching or switching or 'blinding' properly then you are more likely to produce false positive results.

And your sighted comparisons will overwhelmingly produce false positive results for exactly that reason - because it's not just a bad 'test', it's the negation of it.

zobel's picture

and years of reading totally subjective reviews of audio gear, I find myself in complete agreement with you, xnor, regarding the necessity and responsibility of reviewers to make at least one properly run informal blind test to compare what they are reviewing to at least part of the field of competition.
To me, the reviews with that information and some relevant measurements actually mean something and carry some weight, especially if the blind tests show no difference between products.

It is similar to blind taste testing food. In case of a draw, I would like to know the ingredients, and the breakdown of the measured nutritional factors, as well as who made it and where.

John Grandberg's picture

I'm truly sorry you are getting tired of reading this type of review. May I facetiously suggest you stick with only review sites which follow your preferred methodology? Your selection rapidly diminishes there, doesn't it?

You ask: What can reviews such as this tell you in the first place? I'll answer that I think it's pretty straight forward.... it tells you my experience with the device in question, how I enjoy it, what aspects could use improvement, how I feel it stacks up against others, etc. Seems to me this is directly representative of what a potential owner might want to know.

I'd love to get together with Bob and Tyll and some others, to answer the big questions in life. While we're at it, I'd love Tyll's full amp measurement procedure to be available right this second so we can begin to correlate (or at least try our best) what we hear with what we measure. Alas, neither of those are doable at present, so I'm left simply listening and reporting what I hear, using my modest experience in the hobby. Again, sorry if this doesn't satisfy, it is what it is.

SonicSavourIF's picture

Thanks for talking the time to answer, John.
You are right about the necessity for me to look out for articles and websites that follow the methodolody, I prefer. I do so. I stoped devouring articles about electronic gear, I don't believe them to have any validity. Either I don't read them at all or skim through them to see if there is some information, I can use.

For innerfidelity, there are parts or the site that are still interesting for me (like comparing headphones, which just is subjective and the efforts towards more measurements. Yes please! And of course Richard Stallman ocasionally commenting on free software =D). That's why I keep comming back, though I cannot consider every article helpfull anymore.

My rethorical question expresses some frustration because non subjective reviews and relieable measurements are hard to find. Also the remark should encourage you and other contributers to innerfidelity to continue to work towards more measurements and blind testing. For me, this would bring back some trustworthyness to the articles and raise my interest in them.

roskodan's picture

v281, cma800r, taurus, hp8 mk2... paired with hd800

could you describe each of em in one word, in regard to your sonic experience, when paired with the hd800

... i'll accept 'no' too, as a valid and meaningful answer

regards

Bob Katz's picture

Someone should check that out against anything else as a headphone amp. It's only money :-(

xnor's picture

15 ohm output impedance, no feedback, only 10W into 4 ohm ...

Nope.

Bob Katz's picture

Well, Nelson has designs with fractions of an ohm output Z I believe. But it's academic as I'm not going to spend $2000 on an amp right now.

cspirou's picture

Actually the output impedance is meant to be high because its a current driven amp. Similar to the Bakoon hp-21. It actually has added resistors to drop the output impedance from 600ohms. Personally I would rather try it with high impedance. Because its current driven it also means there is less power when you use lower impedance and more power when you increase impedance. This sort of amp was conceived for single full range drivers like Lowthers. For speakers this amp would be very limited however most headphones are essentially single full range drivers so it seems like it would be ideal for headphones. I actually have a DIY project to make an F2 modified for headphone use.

xnor's picture

15 ohm might be considered a current source for 4 ohm speakers, but not precisely for 30-300 ohm headphone loads.

Still, with dynamic headphones you will run into frequency response deviation problems. So I don't see how it is a good match, especially not for a blind test / comparison.
With mostly resistive planar magnetics you will see little difference however.

--

I don't think this makes much sense. If you want high output impedance simply put a resistor in series with the outputs of a 'normal' power amp, e.g. a few hundred ohm.

cspirou's picture

Like I said, the 15ohms can be easily modified to an output impedance of 600ohms so it's not a valid criticism. I agree that I wouldn't use it for the Burson/O2 comparison test but my commentary was more about how the F2 can definitely work for headphones. High output impedance is not always an indication of bad headphone behavior.

http://www.innerfidelity.com/content/musings-headphone-amplifier-output-...

xnor's picture

Sorry, I missed the bit about modifying the output impedance, but I still don't see a necessity to build such an amp. With a 'normal' amp you have the flexibility from ~0 to X ohm output impedance using a simple adapter.

I'm sorry, but what Jan Meier showed is not that high output impedance leads to better performance.
Let's ignore that his electrical model of a speaker completely ignores suspension compliance and suspension loss.. and go straight to what's happening:

If you feed a speaker an impulse the voice coil and diaphragm will start moving. At the end of the impulse this moving mass wants to continue moving - mechanical ringing - that's not what we want.
This movement induces a voltage. Now there are basically two options:
a) the amplifier has a high output impedance, little to no current can flow, the driver will keep ringing
b) the amplifier has a low output impedance, current can flow and the mechanical ringing will be additionally damped electrically

You can simply model this yourself. Without suspension losses and high output impedance the driver would keep ringing for a very long time. With low output impedance it would stop very quickly.

Jan measured the amplifier current which includes this "corrective" current which gets lower the higher the output impedance of the amp.

This is also the reason why you will effectively get a bass boost with high output impedance: the speaker wants to oscillate/ring at some low frequency, and high output impedance enables that.

zobel's picture

You are referring to, and defining what is called the damping factor of an amplifier, which as you know, is the ratio of an amplifier's load impedance to it's output (or source) impedance. The lower the output (source) impedance, the better the amplifier controls driver resonances and ignores load impedance variations.

Another good measure is the slewing rate of an amplifier, which, as you know, is the rate in volts per microsecond at which the output signal from the amp is capable of rising above, or falling below its zero point. These measurements used to be done routinely, and were usually included as part of the published specs of amplifiers.

hd 800's picture

Hi,

great review !

so for what i understood from the reviews, the violectric v281 surpasses the auralic taurus mkii and the icon hp8 mkii when used with the sennheiser hd 800 ? right ?

regards

John Grandberg's picture
I like all three amps quite a bit, but when push comes to shove the V281 in balanced mode is my top choice. Depends on what you are after though.... the Icon amp can be made to sound the smoothest and warmest of the bunch via tube rolling (and/or cranking up the adjustable output impedance). That may appeal to some users more than others.
doraymon's picture

Hi guys,
Thanks for all the very useful reviews.
I have the impression that the headphones amp section of the Wall of Fame is a bit dated.
May I suggest you run a full update of the section with tons of comparisons?
I know it’s not easy but hey, asking is never wrong!
Cheers,
Dom

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