Does Anyone have any experience with Nuforce Amps?

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Adamay

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Nuforce 8.01 highs
« Reply #480 on: 19 Sep 2005, 02:39 pm »
I detect a clear improvement with the 8.01; I had some concerns about my version 8.0, but absolutely none regarding my 8.01.  These amps are subtle, sweet and beautiful from top to bottom, with a huge soundstage.  Currently running with a custom tubed pre, but I have had a Sonic Euphoria passive in the system too; the two preamps have different presentations but I could be very, very happy with either.

gostan

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Tuner Interference
« Reply #481 on: 20 Sep 2005, 10:51 am »
I am seriously missing the triple Ref 9's that I had the opportunity to demo for four days.  The music no longer has that deep bass and full soundstage.  Cannot wait to move my Aragon 8008 to power the surround.  I will count off the days until the Ref 9's that I ordered arrive in early October.  Hopefully, they will be on time.

The only downside was that the tuner section on my Arcam AVP-700 is useless with the NuForce amps in play.  Jason has indicated that the Ref 9's need to be 3 meters away from the tuner and or antenna.  This is impossible for me to do with my system setup.  Is there anything that I can do to alleviate this issue.  The only things I listen to on the tuner are the Patriots and the Eric In The Evening jazz show on WBUR in Boston (it is a fabulous jazz radio show).  The Ref 9's are so good I will give them up, but there must be something else that I can do to deal with the interference.

brj

Re: Tuner Interference
« Reply #482 on: 20 Sep 2005, 01:51 pm »
Quote from: gostan
The only downside was that the tuner section on my Arcam AVP-700 is useless with the NuForce amps in play.  Jason has indicated that the Ref 9's need to be 3 meters away from the tuner and or antenna.

3 meters?

Even if you don't have a tuner in your system, the fact that the amps put out enough EMI to require that much distance makes me wonder how they will affect other components and cabling in the system.  Aren't the amps shielded??

KJ

Does Anyone have any experience with Nuforce Amps?
« Reply #483 on: 20 Sep 2005, 02:26 pm »
Quote from: gostan
Jason has indicated that the Ref 9's need to be 3 meters away from the tuner and or antenna.

3 meters does seem a bit excessive.  I'll have Jim plug in the same units you used this evening and see what happens with a tuner going.

-KJ

gostan

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Does Anyone have any experience with Nuforce Amps?
« Reply #484 on: 20 Sep 2005, 02:27 pm »
There is no interference with any of my other components or interconnects, including my hyper-sensitive turntable.   Generally, unless the tuner in a receiver or pre-pro is well shielded, they will not generate a good acceptable signal quality due to normal RF interference.  As my tuner antenna is RF based, its' proximity to the NuForce amps (which do promote more RF noise/interference than normal amps) is problematic.  But this does not mean that any other component is being affected.  IMO, they were otherwise silent except for the tuner issue.  And, they were the best sounding amps that I have ever had the opportunity to use.

rustydoglim

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Does Anyone have any experience with Nuforce Amps?
« Reply #485 on: 20 Sep 2005, 06:52 pm »
FM tuner uses very low power RF and even if an amp passed FCC/CE certifications, it can still generate sufficient RFI to interfer with FM reception when the antenna is close to the amp.  Therefore we recommend you bring the shielded FM antenna (the tuner and amps can be close together) as far away as possible. Those people with roof top antenna reported no problem with their reception. 5 meters away should allow you to receive most of the channels.

ScottMayo

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Does Anyone have any experience with Nuforce Amps?
« Reply #486 on: 20 Sep 2005, 08:52 pm »
Quote from: nuforce-jason
FM tuner uses very low power RF and even if an amp passed FCC/CE certifications, it can still generate sufficient RFI to interfer with FM reception when the antenna is close to the amp.  Therefore we recommend you bring the shielded FM antenna (the tuner and amps can be close together) as far away as possible. Those people with roof top antenna reported no problem with their reception. 5 meters away should allow you to receive most of the channels.


Um... I've used a variety of amps over the years and I've never had one interfere with an FM tuner, even when the tuner, a dipole antenna and the amps were inches apart. Requiring things to be spread over ten feet apart is extreme.

Devices that put out noise RF really should have internal shields - no exceptions. Especially if you ever want European sales - if I remember, they get stringent on this point. Would it really take more than a metal  foil lining inside the case?

Russell Dawkins

RF contamination
« Reply #487 on: 20 Sep 2005, 09:11 pm »
I think you're right about the European strictness re: RF behaviour.
I wonder if in this case the RF is being radiated from the box or from the wires attached, in which case ferrite chokes around all the attached wires at the closest point to the amplifier should help. If RF is being sent down the interconnects, power cord or speaker wires any of these will serve as a transmitting antenna.

gostan

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Does Anyone have any experience with Nuforce Amps?
« Reply #488 on: 20 Sep 2005, 09:27 pm »
Quote from: nuforce-jason
FM tuner uses very low power RF and even if an amp passed FCC/CE certifications, it can still generate sufficient RFI to interfer with FM reception when the antenna is close to the amp.  Therefore we recommend you bring the shielded FM antenna (the tuner and amps can be close together) as far away as possible. Those people with roof top antenna reported no problem with their reception. 5 meters away should allow you to receive most of the channels.
 Well, I do use a rooftop antenna (my OTA HD antenna) with a splitter that runs coaxial cables to my satellite receiver and to my tuner.

Aether Audio

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Does Anyone have any experience with Nuforce Amps?
« Reply #489 on: 20 Sep 2005, 09:42 pm »
Jason,

Tell Casey to make sure the AC safety ground coming from the power cord is shorted to the chassis as close to the chassis entry point as possible.  We're talking no more than a few millimeters here.  DO NOT allow a "pig-tail" length of it jumper over to the PCB ground-plane first.  That's probably were the problem is if you're bussing your ground over to the board.  Then, just ground the PCB to the board stand-offs.  Star grounding at one point may not work - wavelengths are too short and will radiate from board traces before reaching the chasis ground point.  You may have to tie the plane to the chassis at as many stand-offs points as possible..

You can try the chokes, ferrite beads and all, but you're likely to just push the radiated spectrum around like trying to hold an air buble under water - it just pops up somewhere else.  As long as you get rid of the internal pigtail ground wire and as long as any holes in the chassis are smaller than the radiated waveleghts, you should be able to clean it up with little more than a common-mode choke in the IEC mains connector.  If not, well...please excuse and then quickly forget this posting.  Sorry.

Don't mean to tell you guys how to design, just trying to help.  I've worked with VERY LARGE switching power cicuits in the past.  The biggest was 40 kWin a space the size of 2 shoe boxes that ran (fixed frequency) at 2MHz.  I had the task of cleaning up that very problem in one project - and that's what I found that worked - only after playing around with chokes, beads and caps ad infinitum.

Good luck, I hope this helps.

-Bob

rustydoglim

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Does Anyone have any experience with Nuforce Amps?
« Reply #490 on: 21 Sep 2005, 08:28 am »
Gostan,
We need to investigate this further. I use Denon AV recevivers (48xx and 53xx) and have no problem with using a FM antenna about 15 feet long.

Here's what I extracted OUT OF Arcam AVP 700 manual:
THE AVP700 IS A DIGITAL AUDIO DEVICE WHICH HAS BEEN DESIGNED TO VERY HIGH STANDARDS OF ELECTROMAGNETIC COMPATIBILITY. THE UNIT CAN RADIATE RF (RADIO FREQUENCY) ENERGY. IN SOME CASES THIS CAN CAUSE INTERFERENCE WITH FM AND AM RADIO RECEPTION. IF THIS IS THE CASE, KEEP THE AVP700 PLAYER AND ITS CONNECTING CABLES AS FAR FROM THE TUNER AND ITS AERIALS AS POSSIBLE. CONNECTING THE AVP700 AND THE TUNER TO DIFFERENT MAINS SOCKETS CAN ALSO HELP TO REDUCE INTERFERENCE
http://www.arcam.co.uk/prod_diva_AVP700_intro.cfm
May be with NuForce and AVP the RFI got too high? We're not the only one recommending using long FM antenna  :)

Can you try using the FM ribbon cable that came with AVP700 to see if there's any different ?

Or switch to XM radio  :wink:

gostan

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Does Anyone have any experience with Nuforce Amps?
« Reply #491 on: 21 Sep 2005, 11:51 am »
Quote from: nuforce-jason
Gostan,
We need to investigate this further. I use Denon AV recevivers (48xx and 53xx) and have no problem with using a FM antenna about 15 feet long.

Here's what I extracted OUT OF Arcam AVP 700 manual:
THE AVP700 IS A DIGITAL AUDIO DEVICE WHICH HAS BEEN DESIGNED TO VERY HIGH STANDARDS OF ELECTROMAGNETIC COMPATIBILITY. THE UNIT CAN RADIATE RF (RADIO FREQUENCY) ENERGY. IN SOME CASES THIS CAN CAUSE INTERFERENCE WITH FM AND AM RADIO RECEPTION. IF THIS IS THE CASE, KEEP THE AVP700 PLAYER AND ITS CONNECTIN ...
Jason:
Thank you for this information.  I suspect that this may be a fairly normal disclaimer as I have had issues with FM tuning sensitivity with other built in tuners in receivers.  My demo Ref 9's have now been returned to Jim P. at NextLevelAV, so I will have to await your delivery of my own triplet Ref 9's in early October to experiment with this issue.  FYI, the tuner sensitivity/reception issue has not stopped me from purchasing and awaiting delivery (very anxiously) of these wonderful sounding amps. Early October (I hope they are on time) cannot come soon enough.  I am sure that when I get my own Ref 9's that I can find some type of a work-around.

Jim P. advised me last evening that he conducted a simple experiment with an Arcam AVR-300 and a SN P-965 and that he received fm signals (varying degrees based on the strength of the individual stations) by moving each unit about 2 or 3 feet away from the Ref 9's.

Stan

gostan

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Does Anyone have any experience with Nuforce Amps?
« Reply #492 on: 5 Oct 2005, 12:29 pm »
NuForce Reference 9’s  Review:  My triplets have arrived.

System:  Arcam AVP-700, Denon DVD-2900, B&W N803, HTM1, N805 & ASW-850 and Aragon 8008ST with Kimber 8TC and Cobalt speaker cables and a combination of Kimber, Audioquest and Apature interconnects.

Packaging & Aesthetics:  Each of the three Ref 9’s each came packed in its’ own  “plain jane” box just a little larger than their minute’ form factor with the power cord at one end of the box.  As I unpacked them and lifted each out of the box, I could not believe how light and small they are.  The black versions are well milled and pleasing too look at.  The face plate is plain with a blue power on diode in the middle and no power switch on the front, as it is located in the rear.

Hook-Up:   I checked to make sure that the toggle switch on the back was pointed to RCA and not the balanced connections.   My Ref 9’s came with the upgraded Eichmann Cable Pod connectors and these provide for a very clean and tight speaker wire connection at the amplifier end.

Initial Observations:   Right from the get go it is apparent that these very fast switching amplifiers are very musical in nature with a very low quick bass.  They are dynamic and extremely detailed.  The soundstage is full, but retains its realism.  These comments are made in direct comparison to how my system sounded when being powered by the Aragon amp, and formerly, by a Rotel RMB-1075.

Music Demonstrations:

Julia Fordham-That’s Live:  A great test as the combination of Larry Klein’s bass and Julia’s vocals provide a beautiful but difficult to power low-hi instrument-vocal recording.  The first thing that I noticed is the deep deep bass.  The response speed between Julia’s vocals and the instruments and the individual nature of the sound of each simply sounded wonderful.  I could hear the individual strings of Larry Klein’s bass twanging back and forth. The guitars and vocals on Concrete Love with India Arie and the vocals on Lovin’ You, a Minnie Ripperton composition sounded like I had never listened to either before.  Not different,  but more noticeable and realistic.

Super Session:  Mike Bloomfield’s guitar on His Holy Modal Majesty has always been a favorite of mine.  Soulful and jazz-like, the Ref 9’s definitely bring this recording to another level.

John Coltrane-Blue Train:  I listened to this on SACD and on an Analogue Productions 45rpm recording.  Coltrane’s sound is very different and the reproduction of his tenor sax is true to both recordings.  Kenny Drew’s piano solo on Blue Train again sounds full, dynamic and just like he was sitting and playing in my living room.  For me, the Ref 9’s helped to reproduce this historic recording with a very deep soundstage, when directly compared to other amps.

The Chronicles Of Riddick:   The soundtrack on this one is definitely superb.  A first test of the DD/DTS capabilities of my Arcam AVP-700 when mated with the NuForce amps across the front.  The speed and transient responses of the Ref 9’s really shines with this soundtrack.  I heard individual sounds like the pounding of metal on metal, or a warrior hitting the floor, etc. which I had never heard sounding so real on previous viewings.

Summary:  The amps only been running for about 45 hours.  When I initially demoed them, my comment was that they brought a new speedier and lower bass response and a clearer and more dynamic mid-range to my B&W’s.  My opinion has not wavered.  The NuForce Ref 9’s are small in size, but produce a deep and detailed soundstage.  I am just beginning to realize how musical sounding they are.  They definitely do not change the recording, but I am now able to listen to certain recordings in a different light, as a veil has been lifted, and the recordings have come alive. Only negatives are the lack of power switch on front (I leave them on 24-7) and the rf interference with built in tuner in my pre-pro (I am going to try relocating them further away).  Easy to install and move due to their size, and easy on the pocketbook at a fabulous price point, when compared to many other more expensive amplifier options; the NuForce amps have been worth waiting for.

timothyharnett

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Does Anyone have any experience with Nuforce Amps?
« Reply #493 on: 8 Oct 2005, 07:48 pm »
Quote from: nuforce-jason
Gostan,
We need to investigate this further. I use Denon AV recevivers (48xx and 53xx) and have no problem with using a FM antenna about 15 feet long.

Here's what I extracted OUT OF Arcam AVP 700 manual:
THE AVP700 IS A DIGITAL AUDIO DEVICE WHICH HAS BEEN DESIGNED TO VERY HIGH STANDARDS OF ELECTROMAGNETIC COMPATIBILITY. THE UNIT CAN RADIATE RF (RADIO FREQUENCY) ENERGY. IN SOME CASES THIS CAN CAUSE INTERFERENCE WITH FM AND AM RADIO RECEPTION. IF THIS IS THE CASE, KEEP THE AVP700 PLAYER AND ITS CONNECTIN ...


I'm also having problems with FM reception.  I've got an outdoor aerial with a modern tuner (Sony STSDB900) as well as a Leak Troughline and a Quad FM4.  Basically the Ref 9 killed my reception stone dead and I'm having to use a different amp for radio listening.  It's not bad enough to want to give up with the amps but if there is a mod, I'm interested.  

I'm using a fully grounded power supply with a transormer separating the amps from the power supply.

KJ

Does Anyone have any experience with Nuforce Amps?
« Reply #494 on: 8 Oct 2005, 11:04 pm »
Quote from: timothyharnett
I'm also having problems with FM reception. I've got an outdoor aerial with a modern tuner (Sony STSDB900) as well as a Leak Troughline and a Quad FM4. Basically the Ref 9 killed my reception stone dead and I'm having to use a different amp for radio listening.

Out of curiosity, I plugged in a generic dual-ear antenna to my receiver and sat it directly on top of the Ref 9s.  The only way I could interject radio interference was if the antenna base was sitting directly on top of the amps.  I only had to move it 1-2 inches away and everything cleared right up.  What is the proximity of your tuner to the amps Timothy?  BTW, welcome to AC!

-KJ

timothyharnett

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Does Anyone have any experience with Nuforce Amps?
« Reply #495 on: 9 Oct 2005, 01:55 am »
Quote from: KJ
Out of curiosity, I plugged in a generic dual-ear antenna to my receiver and sat it directly on top of the Ref 9s.  The only way I could interject radio interference was if the antenna base was sitting directly on top of the amps.  I only had to move it 1-2 inches away and everything cleared right up.  What is the proximity of your tuner to the amps Timothy?  BTW, welcome to AC!

-KJ


Hi KJ,

About 1.5 feet diagonally in an Arca cabinet.  I'm actually going to go to the trouble of having a new aerial mast erected with new shielded down line.  Hopefully the extra shielding will help.  

Really impressed with the amp but it feels like a defeat to turn it off and switch to the T amp when I need the radio!  I'll try what you suggest with the aerial on top of the chassis.

I can get digital (DAB) radio but the audio quality is poor when you move away from the analogue format.  DAB isn't really hifi.

While the problem remains, it would probably prevent me from moving forwards and bi-amping at some later stage.

mmm

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Re: DC Offset Deal Breaker
« Reply #496 on: 14 Oct 2005, 06:22 am »
Quote from: Casey


In general, only Apogee users have to be concerned with the 0.1V DC offset, this is not an issue with all other speaker types.

The 24VDC to ground limit with the Definitive Technology is because of its built-in subwoofer amp tapping signals from the speaker terminals ...


I will use a TBI active sub (via speaker terminals, no alternatives)and Fostex speakers which have no crossovers and caps to filter out DC...

so do I have both issues to deal with??? I will receive my ref 8 soon..

is it possible for me to change the opamp mysel? I read something says that the DC offset is from the opamp?? If this opamp is not a Surface mount part, I will really like to do it myself...

any dc from amplifier speaker outputs  can be SEEN on my tiny fostex derivers, which have very short p-p linerty.....
:nono:

thanks..

thanks...    :mrgreen:

rustydoglim

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Does Anyone have any experience with Nuforce Amps?
« Reply #497 on: 14 Oct 2005, 09:04 am »
Quote
I will use a TBI active sub (via speaker terminals, no alternatives)and Fostex speakers which have no crossovers and caps to filter out DC...


The small DC offset between the TWO speaker terminals should not hurt your speakers (we have no complain at all so far). The power from 0.1V DC is too small to cause any problem.

BUT, the 24V DC offset between EACH speaker terminal and ground will present problem for some active sub. I believe it is a problem for TBI active sub.  Don't connect it to your TBI directly. Connect each speaker terminal to a capacitor to block out DC that can reach the TBI.

rustydoglim

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Does Anyone have any experience with Nuforce Amps?
« Reply #498 on: 14 Oct 2005, 09:06 am »
Alright, another reviewer has chosen NuForce as his reference amp.
Erik Vermeulen, hifi.nl
"...The NuForce amplifiers have stolen my heart. They will no longer leave my house. I will use them as my reference amplifier from now on. Every amplifier which I will listen to in the future must be compared to NuForce."
http://www.hifi.nl/recensies.php?id=2429

mmm

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Does Anyone have any experience with Nuforce Amps?
« Reply #499 on: 14 Oct 2005, 11:10 am »
I bought four NX series Black gate 1000uf 25v..... I guess that's ok!??? they will not cut off any low frequency I guess??

Can i purcahse the litz wire from nuforce at all?? what brand is it??

thanks