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NuForce DDA-100 impressions thread (computer, but not headphone, DAC/amp) - Page 4

post #46 of 72
Originally Posted by chrisnew View Post

How about this?
Behringer UCA202 2-In/2-Out USB Audio Interface S/PDIF Out



Thanks Chris. Are you using this?  All I know about Behringer is that they put low-quality studio equipment on the market in the 90's ;-)


Thanks anyway. I believe I first should follow the advice from Barbes above and let it 'burn-in' some more before I invest in a DAC's or UPS's etc. Even though my feeling about ''burn-in' is that it's merely listener habituation time.

post #47 of 72
Double post
Edited by chrisnew - 1/17/13 at 5:39am
post #48 of 72
Originally Posted by briansorensen View Post

Thanks Chris. Are you using this?  All I know about Behringer is that they put low-quality studio equipment on the market in the 90's ;-)

Thanks anyway. I believe I first should follow the advice from Barbes above and let it 'burn-in' some more before I invest in a DAC's or UPS's etc. Even though my feeling about ''burn-in' is that it's merely listener habituation time.

Good choice, Brian.

Nope not using it, but read good things about it being value for money and giving those costing several times a run for their money. Furthermore, imo, it doesn't make sense to buy a converter that cost the same as the amp.

my speakers are on the bright side of things and my ears definitely don't take well to listening fatigue. Both my pioneer and nuforce sound better after run in, removing that bright edge that caused fatigue. Give it a shot smily_headphones1.gif
post #49 of 72



We're sorry to hear of your experience and you can rest assured your observations as well as those from a handful of others certainly have us perplexed.  As most have read or heard by now from both professional reviews such as that from TAS as well as private users, most customers experience an exceptional level of performance from the DDA-100 and are quite pleased with it.  As it stands, the torch has been passed to me in the effort to analyze why there exists this handful of negative experiences.  What I have discovered is as follows:


First, there is the issue of break-in.  Most agree the effect is real and that some minimum amount is required for any audio product to perform at its best.  Being an engineer, that concept has always represented a bit of a mystery to me.  Of course, I have experienced it personally... so I know the effect is real.  But, one would suspect that it be more commonly encountered in analog equipment.  Capacitor dielectrics are known and have been proven scientifically to relax over time, becoming "faster" and exhibiting less hysteresis than when first placed in operation.  It's a fact of physics that all materials change somewhat over time.  The real mystery is how the multitude of variables in an audio product can change, such that they converge over time to yield better sounding performance.  Why doesn't the product end up sounding worse rather than better?  You'd think that statistically, it would 50% of the time?  But no... they always seem to improve - or at least stay pretty much the same.  Maybe the effect is akin to a well-worn pair of shoes becoming more comfortable? Who knows?


All we know is that from our own empirical observation is that virtually all audio products benefit from a certain amount of break-in, with the DDA-100 being no different in that respect.  Seeing it is an all-digital device, that seems even more perplexing... at least to me personally.  The only thing I can make a guess at that might be going on is that the PWM output stage has parts that are "relaxing."  Seeing that all PWM amps do have a number of passive parts associated with their construction, that would make more sense.  Whatever the cause though, empirical observations made by both ourselves and others seem to indicate that a solid 75 hours of break-in seems to be the "magic" number for the DDA-100. (I hate that word).


With regards to your specific case, the only other variable is the speaker used and (to a far lesser degree) the speaker cables.  I don't even wanna touch the cable issue as I'll be here all night.  Speakers, on the other hand, have numerous variables with all of their moving and non-moving parts (not to mention parts that move, but aren't supposed to).  Being a loudspeaker designer myself, I could go on forever with this line of discussion, but it would be better to stick to the reported observations of others.


John Marks of Stereophile reported in his column regarding the Dali Ikon 2 :


"Due to the Ikon 2's crossover design, DALI recommends that the speakers be set up with zero toe-in..."


That tells me (as a speaker designer) that the Ikon 2 has a slightly accentuated high frequency response - probably a result of the crossover at 14kHz to the ribbon tweeter it uses. At 14kHz there is probably a (relatively) broad hump (+ 3dB maybe?) in the on-axis response, so keeping the speaker toed-out reduces the hump at the listening position because the dispersion in that range is relatively narrow.  If listened to on-axis, that hump could result in a bright and excessively detailed (i.e., irritating) sound.


Then Marks goes on to say:


" I can easily imagine a person whose musical tastes are similar to mine, but who has a more acoustically damped room and whose listening position is farther away than mine, being very happy with the Ikon 2s. And people whose listening tastes are not like mine will prefer this speaker's clarity to that speaker's warmth. Not that the Ikon 2 is cold; it's more like "nonpartisan."


John Marks makes it a point to state that the speaker is not "cold" sounding?  Hmmm... Also, that listening "further away in a damped room" may be better? It's a fact of physics that greater listening distances = less HF energy.  None of the above is intended to imply that the speaker is in any way "at fault," per se.  Just that it might not be a good "match" for the DDA-100.  Overall, John Marks gave the Ikon 2 a big "thumbs up" and we are not about to take issue with him on that.


UPSHOT: Factor in the above and for use with the DDA-100, we recommend speakers with a flat frequency response.  Better yet, maybe even with a slightly "tilted-down" HF response above 5kHz.  Not much though.  Only 2 dB or so at 15kHz. should be plenty.  This makes sense because unlike much analog gear, an all-digital design will have an extremely detailed HF response. There is absolutely nothing in the signal path like stray capacitance or inductance that will tend to soften the top end, like there can be in analog equipment and interconnecting cables. That being said, if one adds a boosted top end from the speaker to an amp like the DDA-100... then everything may start falling apart rather quickly.  We hope this helps.
Take care,
-Bob smile.gif
post #50 of 72
Bob, glad to see the manufacturer paying attention to feedback in the forums. just curious, will we potentially be seeing any upgrades for the dda-100 from nuforce?
post #51 of 72
Hi Bob, another question. Why does the dda-100 sound better at higher volume? Is it down to the power or is there another explanation?
post #52 of 72


Dear Bob, 


Thank you for paying attention and spending your time on this.


As said, I will grant the nuforce some benefit of doubt and let it play a few more hours before I conclude anything or invest in remedies. I am keeping expectations low though. It seems that neither of us really believe in ‘burn-in’ time, but for very different reasons, we have somewhat surrendered ourselves to earwitness accounts of this strange phenomenon. As you point out it lacks technical explanations and until I have heard it for myself, I believe it’s all about the ears and brains get accustomed to the sound, more than it’s the equipment growing up. As opposed to the nuforce, we’re human and have survived as a race because we are able to adapt to almost anything. Eventually, my brain will start compensating for gaps, holes, peaks – any flaw in the sound reproduction, and, as bad as it ‘objectively’ sounds, my nuforce will become my new reference for proper sounding hifi. 


I cannot make myself blame the Ikon 2 speakers. Especially not in the high frequencies. Of all the speakers I have listened to over the years, none in this price range have reproduced horns, cymbals and vocals more convincingly. As it’s said in this review in What hi-fi, "That twinned-tweeter arrangement works well, too. The pairing of conventional soft-dome and ribbon keeps dispersion wide – so toe-in isn't so critical – and ensures truly extended highs."


My nuforce or speaker setup does not need fine-tuning. My problem is not just the treble and it’s not at all minor details that I am unhappy about. Overall performance is just really bad. It sounds like you would expect it from any cheap digital amp. Bass/drum is weak and imprecise (drum are suppressed at all volumes), the mid-range is acceptable, but hollow and enclosed – the sound does not come out and detailing is weak. Stereo perspective is flat and listener positioning becomes critical. Treble is strained and unnatural – detailing not impressive. Sound reproduction is generally inconsistent. You never know how the music will sound. Even the volume changes. You just know its’ going to be unmusical, uninspiring and unpleasant.


When my nuforce has played some more, I will take advantage of its tiny size and bring to my friends and try it there with their speakers and room layout. That should also take the listener habituation out of the equation.


Bob, I have a question. My nuforce DDA-100 was bought here in January 2013. Is there any reason to believe, that my unit is different from the early production units that have previously been tested with strong results? 


post #53 of 72

Dear Brian,


Sorry for the late response. Just heard back from engineering and my "skeptical" suspicions were right.  Turns out the Wima capacitors have a long break-in period and once they settle in, they make a BIG difference.  I know for a fact as it has been demonstrated with clear measurements and scope photos that capacitors DO change over time.  Due to the molecular mass of the dielectric materials (the "stuff" between their plates such as Mylar, Teflon, etc.), they exhibit a property known as "hysteresis."  It's a type of "memory effect" where the material tends to retain a bit of the signal that it was just exposed to.  Transformers or coils with metal cores are well known to exhibit this effect, and therefore it is the main reason we don't like to use (if we can avoid them) iron-core coils in speaker crossover networks (I'm a speaker designer too :-), because it causes significant distortion. In mechanical systems it's called "back lash."


Anyway, as the dielectric material is repeatedly exposed to a changing voltage and current, the bonds between the molecules weakens or "softens" a bit. Not enough to be detected in a physical strength measurement, but enough to allow the molecules to change their orientation in the molecular matrix more quickly.  When the electric charge on the molecules' surface doesn't "flip" polarity as fast and in lock-step with the applied voltage, that represents the memory effect or hysteresis - which is (or ends up being) distortion. So, the "faster" the capacitor (meaning its dielectric), the less added distortion from hysteresis.


Well, the same properties (high dielectric constant) that make a good dielectric (at least the plastic based ones), the longer they take to "soften up."  In fact, some of the most highly rated caps are reported to take a very long time to break in.  As an example, one of my former speaker customers wanted me to build him external crossovers for the speakers he purchased from me, and he wanted "the best" capacitors, coils, etc.  Well, the "customer is always right" so I built them - nice, big and EXPENSIVE. Then when I listened to the system before I shipped it out, I thought "my God, these things sound worse than the standard crossover parts."  I was about sick thinking how much $$$ this guy had thrown away.


Anyway, he gets them and is totally cool about it, saying that he knew they would take some time to break in.  Every week thereafter I got a new report on how they were doing.  Finally, after he reported about 700 hours on the speakers, he said they were pretty much broken in, had settled down nicely and were sounding wonderful. "Well... Okie Dokie then - so long as he's happy" :-) Whew... whatever!


Then a year or so later I had cause to visit him and got to hear just how good "my" speakers were. HOLY $#@! They did sound fantastic - nothing like the pieces of "crap" that I heard before I shipped them out.  Now remember... these were my "babies" and I had been listening to numerous pairs of their elder siblings for years. Every "parent" knows its kid like nobody else. Talk about "Invasion of the Body Snatchers" though? I scarcely recognized them as my own design (except nobody else' could have touched them in performance to begin with, so they had to be mine :-))


So now I'm a "reluctant" believer in break in. I still don' like the idea, but I can't deny the effect's existence.  OK then... Wima caps are VERY good capacitors, so I'd expect the same from the DDA-100 to some degree.  Therefore, if that darn thing doesn't start sounding good after a few weeks (at most), contact us at NuForce to get a replacement unit... 'cause yours is frick'n busted. That's the only explanation that makes sense.  The power supplies were changed, but the present production is supposed to be better than the "Off The Shelf" ones used early on.  That's why it was changed and a new one was designed from scratch.  After internal review, the OTF ones weren't considered to be quite as good as was expected.


Take care, smile.gif


post #54 of 72

Dear chrisnew,


Thanks... we try.  Just need a few "more" of me to keep up is all. confused_face.gif


I doubt there will be any future upgrades available for the DDA-100.  Unlike our Reference Series products, that some models of which do get upgraded from time to time (like our Ref Series amps), it's a model in our Home Series.  I don't expect any of those models will be upgradeable.  Then again, I don't work directly in product development, so what do I know?  The engineering gurus manage to surprise me every once in a while.  What I have heard though is rumors of another model based on the same technology that *may* be on the drawing table.  Don't know if it will have more power or less though.  Truth be told, I really don't know enough of anything certain to make it even worth mentioning.  "Ignorance" never seems to stop me though - hasn't yet anyway. etysmile.gif  If interested, just keep watching our website. We'll all (including yours truly) probably find out at about the same time.


As far as why the thing is reported to sound better at higher volumes goes... your guess is as good as mine. I know that data isn't being dropped due to digital attenuation, so what the heck is going on has me puzzled. Being a speaker designer, I wonder if it isn't the speakers and the ulta-low distortion from the DDA-100 at low levels.  I know from my own speaker designs that they offer exceedingly low levels of distortion over the whole range and a dynamic capability that will leave your ears ringing while the speaker barely breaks a sweat. You know what, no matter the electronics ahead of them, they don't "come alive" until they're playing at a certain level.  I can measure anything you want - THD, IM, Phase, Spectral Waterfall, Burst Decay, Dynamic Linearity... you name it.  All the specs look more like a good amplifier than a speaker at ANY level (which few would believe unless they'd seen the measurements for themselves). Makes no difference.  They don't "sing" until they hit "XX" dB SPL - period.  In fact, my smaller models (monitors) that DISTORT sooner (at lower power levels) actually sound BETTER than my bigger "better" models at lower listening levels. The big floor-standers just have to be "pushed" harder to start really sounding good. Go figure.


The only explanation I can think of - and God how this grates on my engineering brain - is that we must all "like" or "need" a little distortion to fill in for what's lacking in the recording process??? As much as I hate the very thought of that concept, I don't know what else is left to explain the effect.


A funny thing happens on the other end of the volume spectrum though too.  The lower the speaker's distortion (electronics quality being a fixed constant and no amplifier clipping), the LOUDER you can play the music without it actually SOUNDING loud.  This was always the bane of my speaker designs because folks thought they needed a lot of power.  They didn't "need" any more power than any other speaker of the same sensitivity and impedance.  But because they played so cleanly at such high volumes, they didn't SOUND as loud as they were actually being played.  Therefore folks never realized how loud they were listening and pushed their amps to the limit.  THEN... when they could clearly begin to hear AMPLIFIER CLIPPING kick in, they thought, "Gee... these speakers really need a lot of juice."  If they had used an SPL meter so they could have seen how LOUD the music really was, they would have freaked out and turned the volume down just to save their ears from damage.


So I suspect our brains are "wired" such that distortion is a necessary part of our hearing experience.  I also think it has something to do with dispersion too and how it relates to volume. I've always noticed how wide dispersion speakers (especially omnidirectional types) seem to sound better than others of narrower dispersion at lower volumes.  Without the added room reverberation that results from wide dispersion speakers, maybe our brains get confused and loose their sense of "spacial recognition" when listening to speakers at lower volumes.


Makes sense because the ambient cues in the recording would be at such low levels when listening at low volume that they would be "buried in the mix."  Maybe our brains need a certain ratio of direct to reflected sound in order to process the spatial location of instruments and voices.  When listening to a stereo system (i.e., an artificially reproduced sound stage) at low volumes and with speakers of moderate dispersion properties, the ambient cues just aren't of sufficient volume to impart the illusion of "real-ness."  Spray the same sound at the same volume around the room a bit more (with wide dispersion/omni speakers) in order to "synthesize" a proper direct-to-reflected energy ratio... and VIOLA!!! Everything sounds as it should.


Could be wrong, but Bose sure made a name for themselves starting out with the original 901... for some strange reason.  In lieu of a  "synthesized" sound stage, then when using more "typical" speakers of average dispersion, maybe all that's left is to... TURN UP THE VOLUME so you are able to hear the real sound stage captured in the recording. In addition, if the amp and driving electronics are of exceptionally low distortion (read: DDA-100), then *maybe* you have to turn up the volume even MORE.


But I'm just a hack, so what do I know?  By the way, did you know that human hearing is very non-linear such that certain ranges/frequencies have to attain a certain minimum volume to even be heard AT ALL???  It's called the Fletcher-Munson hearing curve, with bass being the hardest to hear.  Hence, the old "loudness" controls you used to see on stereo receivers.  Heck, a 20Hz tone has to be a minimum of 80 dB to just be barely audible.  Try that at 3kHz and see what happens.  You'll be sticking your fingers in your ears and wincing at the same 80 dB level.  So in light of the above, is it any wonder why we all like to "turn up the wick" once in a while?  In some cases... it might even be necessary just for a given combination of components to start sounding what we all call "GOOD."  Hey, maybe there's nothing wrong with that new digital gizmo after all! :-)


Take care,


post #55 of 72

Dear Brian,


I suspect that your gears are not matching well with DDA-100. Do your speakers have a low sensitivity?


I listened to the amp at a local shop a month ago. The brief audition session was very disappointing. The tone of every orchestral instruments, especially the lower-pitched ones, and the human voices all sounding unbelievably thin and therefore screechy.


But then I contacted the sole agent of nuforce here and to my surprise, they sent the amp to my place and offered me a trial period on it for a few days. I tried it with a pair of Rogers 3/5A and a pair of wharfedale floorstanding, connected by audionote speaker cables. It sounded completely different from what I had heard at the retail shop. The tone was not thin at all, although right out of the box, it didn't sound smooth enough, especially at higher frequencies, and the sound stage was a bit compressed. But the separation of instruments, the black background and the detailed tonal presentation were impressive. After burning in for a few days, the sound smoothed out and opened up. Now the timbres of the instruments and voices are naturally sweet and rich, although it doesn't have the warmth from a tube amp. The performance is formidable, and at this price, it's a real bargain.


Strangely, I found that it goes better with the wharfedale floorstanding (sensitivity: 89dB) than with the much smaller 3/5A, which has a lower sensitivity (83dB).

post #56 of 72
Originally Posted by Gavin Ly View Post

Strangely, I found that it goes better with the wharfedale floorstanding (sensitivity: 89dB) than with the much smaller 3/5A, which has a lower sensitivity (83dB).


Nothing strange about it :)


83db is a power guzzler, terribly inefficient. It's a standard sensitivity of the BBC monitor design. Even the new harbeth one is 83db.


The nuforce shouldnt be paired to something below 88db. Even 88db is at the limits of what I feel the dda-100's advantages can provide.

post #57 of 72
I disagree - I'm having good results with several monitor speakers in the mid 80dB range. I guess it depends on how loud you want to go.
post #58 of 72

Hi guys!


What kinds of speakers do you use with this amp - what kind of floorstanders would you recommend for it?

post #59 of 72
Originally Posted by briansorensen View Post

Thanks Chris. Are you using this?  All I know about Behringer is that they put low-quality studio equipment on the market in the 90's ;-)

Thanks anyway. I believe I first should follow the advice from Barbes above and let it 'burn-in' some more before I invest in a DAC's or UPS's etc. Even though my feeling about ''burn-in' is that it's merely listener habituation time.

How is the run in, brian?
post #60 of 72

Didn't get any replies above. Currently I am using Klipsch RF-52 speakers with my DDA-100 but sometimes I find them a bit bright and tiresome when the materieal isn't top notch.


Anyone care to name some speakers they have found matches well with it. What speakers are used by Nuforce when demoing the kit?


I am mostly into floorstanders.

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