Does Anyone have any experience with Nuforce Amps?

Rocket · « **Reply #60 on:** 12 Apr 2005, 10:56 pm »

Hi Jason,

Thanks for the clarification regarding the gain setting of your amplifier. From what i have heard from werticus these amps are selling well in oz.

Werticus,

I wouldn't say that i am impulsive but I have had a bad run with amplifiers. I spent $2500au on my n.e.w. dc - 66 amplifier and it was a bad really bad investment. I had my aksa amplifier for over 2 years and really enjoyed it but i was ready to move on and try something different. It is a pity about the timing of the nuforce amplifiers as i only just purchased my amp in february.

The rest of my system is settled. speakers 5 years, preamp 4 years and dac is 3 years old.

Btw who built your speakers?

Regards

Rocket

nuforce · « **Reply #61 on:** 13 Apr 2005, 03:41 am »

Yap, we can't make them fast enough and have to go into allocations for dealers. New dealers who order 1 pair and existing dealers gets the priority. If you're end user and you don't have a dealer in your area, you might want to consider placing an order now for end of April or May shipment. We won't sell to users in the area where there is a dealer.

Jason

WerTicus · « **Reply #62 on:** 13 Apr 2005, 04:44 am »

nuforce: T-shirt!, sweet mate. one review coming up...

I'm afraid I'll have to be totally honest in it I wont lie for you! No matter how many Tshirts are on offer

rod:

glad to hear you have most of it sorted out - why dont you borrow a pair of nuforces from pat for a while - he would let you for a week or so and then you would know or not if your happy with what you have

i hate to see ya suffer

and it would be even worse if you switched over and felt you made a mistake.

also im surprised the NEW you didnt like - because i tried the 10w version and it sounded wonderful, just needed more power.

Agisthos · « **Reply #63 on:** 13 Apr 2005, 02:12 pm »

Jason, is your digital amp similar in technology to what these guys are doing? www.mueta.com

nuforce · « **Reply #64 on:** 13 Apr 2005, 04:26 pm »

I have never heard about their amp. I don't know if they're shipping any product or just a technology provider. Similar to switching power supplies, there are many topologies for switching amplifiers. Many companies have patterns and designs out there. Each modulation techniques or feedback & control system could be slightly different.
But actually come up with a good implementation that sounded very good is a different ball game. Our CTO got his first pattern granted in 2002. We have subsequent refinement and pending patterns in US and EU. It took us almost an entire year to go from 1st working prototype to the current shipping product.
Class D amplifier technology is quite common out there, just look at how many Class D ICs on the market. But going from IC with good THD spec to a high power system that sounded good requires different skills. Therefore you don't see that many good sounding (audiophile standard) switching amp on the market. We expect more of these systems to be available in 2006 as people begin to recognize the advantages and acknowledge that switching amp can indeed sounds as good as linear or tube amp (or even better).

Jason

Harmon · « **Reply #65 on:** 13 Apr 2005, 11:41 pm »

Could you provide us with a graph showing THD+N vs. Output Power of any Nuforce Amp. Thanks

nuforce · « **Reply #66 on:** 14 Apr 2005, 06:16 am »

We're waiting for more compresensive plot of the amp (with the power supply), should be available next week. Here's a typical plot at 1Khz, which is not comprehensive enough:
http://www.nuforce.com/picts/nuforce_thd_vs_power_1khz.jpg
Here's freq response:
http://www.nuforce.com/picts/nuforce_freq_100khz.jpg

enzo · « **Reply #67 on:** 14 Apr 2005, 04:50 pm »

Jason:
Can you also provide distortion vs. noise graphs of the individual harmonic components at various frequencies? For example, the level of 2nd order through 9th order harmonic distortion (in dB) at 50Hz, 1kHz, and 20kHz.

I'm specifically interested in the relation of upper-order harmonics to low-order, particularly at high frequencies, since this is where the several class D amps I've auditioned have disappointed me.

Thanks!

cryotweaks · « **Reply #68 on:** 14 Apr 2005, 08:14 pm »

I will have photos up soon, and impressions up next week. Will probably start a new post.

audiojerry · « **Reply #69 on:** 15 Apr 2005, 01:24 am »

My audition units arrived today, and I'm in the process of burning them in. I checked to make sure everything was working properly but I did sneak in a brief listen. Very quiet, and I must admit I am impressed by how pristine and clean it sounds right out of the box. No nasties, no harshness, very easy on the nerves.

I can't get over how tiny these monoblocs are!

Stay tuned for more.

Carlman · « **Reply #70 on:** 15 Apr 2005, 01:44 am »

Quote from: enzo

Jason:
Can you also provide distortion vs. noise graphs of the individual harmonic components at various frequencies? For example, the level of 2nd order through 9th order harmonic distortion (in dB) at 50Hz, 1kHz, and 20kHz.

I'm specifically interested in the relation of upper-order harmonics to low-order, particularly at high frequencies, since this is where the several class D amps I've auditioned have disappointed me.

Thanks!

Yes, Jason... we need to see every conceivable graph, chart, and analysis of your gear possible so we can know whether it will sound good.

I'll need the schematics, hook-up wire, and type of solder as well. I've been dissapointed when people used anything other than 14% copper content certified solder and Ultralitz-knotbraid cabling...

-C

nuforce · « **Reply #71 on:** 15 Apr 2005, 08:10 am »

Quote from: enzo

Jason:
Can you also provide distortion vs. noise graphs of the individual harmonic components at various frequencies? For example, the level of 2nd order through 9th order harmonic distortion (in dB) at 50Hz, 1kHz, and 20kHz.

I'm specifically interested in the relation of upper-order harmonics to low-order, particularly at high frequencies, since this is where the several class D amps I've auditioned have disappointed me.
!

You ought to be dissappointed. All current Class-D measurements are conducted with a brick-wall filter cutting off >20Khz information. Needless to say, you'll get pristine -100dB plots and perfect 0.001% measurement at 1Khz. The modulating frequency will cause trouble to the distortion analyzer, read white paper in Audio Precision web site.

nuforce · « **Reply #72 on:** 15 Apr 2005, 09:21 am »

I will add to what my colleague just posted. Our measurement should look pretty good, as we have done on earlier PCB. One of the challenge in measuring switching amplifier (see http://www.audioprecision.com/index.php?page=resources&id=1000000162) is how to seperate the very low level modulating frequency from noise and distortion. This is especially hard when an amplifier such as NuForce has 100Khz of bandwidth. User after user have found that this amplifier provide a wide sound stage among other benefits. We believe it is the effect of the wide bandwidth that allows hunman ear to distinguish the position of the sound. You can try this experiment if you have an AP equipment. As you move up the cut off frequency, the THD+n goes up proportionally. What it tells you is that the measuring equipment is being confused by the modulating frequency and think that it is noise. Publishing only 1Khz plot is a joke. But that's the best number everyone is able to get. We will show THD vs Freq plot and also THD vs power plot AT DIFFERENT FREQ.

You will also find almost all vendors use AES17 filter set at 22khz cut off. The effect of doing that is to practically drop the THD+N of anything > 10Khz. Meaurement result can be manipulated and presented in the best light.

For all those skeptics out there, I would say read up on the tech notes at Audio Precision website (so that you can tell if the vendor is hiding something), interpret the plots yourself, don't believe in marketing BS that claims 0.0x% THD at 1Khz. Or 0.0x% at 300W. Come on, as the power goes up, noise becomes less of a component of the output voltage.

You will hear what Jerry has to say. He is the first guy who recieved the amp in audition. We just posted a review from a user on the website. He is not a dealer. Listen for yourself. What we wrote on our website (home page, FAQ etc) are not marketing BS. Well, it certainly sound like it when you first read it. How can all that be true.

Well, we let our customers speak for us. It is time to throw away the misconception that a top performing amp has to cost a lot of money. Some people will say, hey, the amp is so small and light, there's nothing here. But wait a minute, look closely. What do you see in a linear amp that weighed 100 lbs ? Most of the space are filled up by big transformer. NuForce amp has more components than any linear amp. And it is not digital. If you compare all the reviews, you will find something unusual. They're all pretty much saying the same thing. We're still pretty shocked by what people have been telling us. If we have to write the reviews ourselves, we don't even dare to write it that way, even if we're a little drunk

.

Ok, lets see what Jerry has to say. Who knows, he might be the first one to say we suck. By the way, if you can read Italian, Dutch or Swedish, go read what those customers have to say on the internet. We have an Italian customer who started posting all over in Italy 2 days after receiving the amp.

Jason

WerTicus · « **Reply #73 on:** 15 Apr 2005, 12:36 pm »

nu force is where it is at ladies - I didnt even bother to look at any specs after hearing the thing for 2 hrs I bought one.

Your own ears will not lie - full review next week from me - the break in is about half way!

audiojerry · « **Reply #74 on:** 15 Apr 2005, 02:54 pm »

Fresh out of the box, the Nuforce sounded surprisingly good.
Four hours into burn-in, I snuck another listen. It didn't sound so good then. I've had this experience with other components during burn-in - especially interconnects and cd players. They start out good, then go into some kind of funk for awhile, and later emerge into the butterfly (bad metaphor). Another strange thing - at low volume the Nuforce sounded anemic with weak bass, but when I cranked it up, things improved significantly.

Nuforce, are you aware of this phenomenon?

cryotweaks · « **Reply #75 on:** 15 Apr 2005, 03:31 pm »

Jerry,

Read the WAR audio review on the nuforce web site. They experienced the same issue.

enzo · « **Reply #76 on:** 15 Apr 2005, 03:45 pm »

Thanks for the diatribe on measurement difficulty Nuforce. That probably accounts for the class A rating of the PSA HCA-2 by Stereophile, despite the rapid rise (and spike) in distortion over 20kHz... Their measurements may not have given an accurate assessment of its performance. I think the class A rating resulted more from their subjective opinions...

Having said that, John Atkinson's harmonic spectrum component of his technical reviews can tell one a lot about what the amp may sound like, hence my request above for your spectrum of harmonic components. Do you have these specs, or do you not really use them in voicing your product?

nuforce · « **Reply #77 on:** 15 Apr 2005, 04:43 pm »

Oh, I know what happen to your low volume problem. A batch of units that first came out of this production (not those that went to Australia) have the gain set to 23db (oops). I think the unit was sent to Jerry before we caught the problem and fixed it. When you send it back to us after the audion, we'll fix in for the next person in line.

Jason

WerTicus · « **Reply #78 on:** 15 Apr 2005, 05:36 pm »

yeah my pair went through a 'bad' phase...I actually checked all the connections it was so wrong....

found nothing wrong, left them on all night and the next morning they were great. At 15 - 20 hrs now and they sound perfect IMO, but then again slightly better than last time i listened

Looking forward to further break in!

One happy camper here people. Today i decided to see how loud i could push them - and they went well into 'im going to go deaf' territory on my 89db speakers, with absolute and perfect clarity.

and when you do push it so far she clips in a very gentle sort of way... its interesting

But you can reallllly appreciate the low distortion at high power these amps are capable of!

ted_b · « **Reply #79 on:** 15 Apr 2005, 06:06 pm »

Jerry and Werticus,
What speakers are the Nuforce amps driving? I did a search for "speakers" on both of you but couldn't find where you referred to your system layout.
thx,
Ted