Shielding NuForce amps?

highdudgeon · « **Reply #20 on:** 8 Jan 2006, 11:08 pm »

Why should it matter whether the amps are plugged into a voltage/current regulating surge protector (ie, like a Monster device)?

Also, what would account for the very audible buzzing of the amp, v. 9.02?

rustydoglim · « **Reply #21 on:** 10 Jan 2006, 09:57 am »

If you encountered any audible buzzing, you're having ground loop noise. Every products inevitably will encounter such problems (incompatibility between components). You should contact [email protected].

NuForce Ref series amps and preamps' switching power supply already does the voltage and current regulation so plugging it into another power conditioner that does that appears to affect the sound.

Adamay · « **Reply #22 on:** 11 Jan 2006, 08:13 pm »

I have posted here about Nuforce RF interference with my tuner, and feel I need to give an update & mea culpa. In checking alternative shielding possibilities, I noticed that my FM antenna cable's ground lead had become disconnected from my tuner. Doh! I hooked it back up and the RF interference vanished. Nada. Brilliant, clear reception from a station 50 miles away _in stereo mode_. My recent concerns about RFI from my Nuforces are gone! Had me laughing for a good half-hour. (Tuner is a Sansui TU-217.)

rustydoglim · « **Reply #23 on:** 12 Jan 2006, 10:27 pm »

NuForce amps (current version) have RFI on FM or VHF TV but it is still possible to get good reception.

We found that a combination of the following works well:

- Good grounding in the system
- Use external antenna. If that’s not possible, use a long (>5m) shielded coaxial cable to reposition FM antenna.
- Do not use solid core speaker wire
- Use shielded or twisted pair interconnect
- Ref 9.02’s grounding scheme further reduce the RFI by 10db.

If you can get Satellite TV/FM, go with it

Halfdeaf · « **Reply #24 on:** 20 Jan 2006, 06:44 pm »

In my case the amps are about 16 feet away from my tuner (Magnum-Dynalab FT-101[modified]) which is using a MD SR100 indoor antenna, and I cannot receive any stations at all on the tuner.

Additionally, the amps are about 3 feet to the side of my television (Sony XBR) which receives its signal via cable, and channels 2 through 6 snow-out so bad they're unwatchable when the amps are on.

I love the sound of the amps - haven't heard this kind of bass control on a speaker since I got rid of my old Phase Linear 400 (with a DF>1000) 25 years ago - but it looks like I'm going to have to give 'em up.

(*sigh*)

Halfdeaf

rustydoglim · « **Reply #25 on:** 20 Jan 2006, 08:40 pm »

You should switch to Satellite TV and don't use VHF TV channels.
It is a matter of placing the antenna (not the position of tuner), using the right shield antenna wire and adjusting the cable to avoid the RFI.
You should email to [email protected] and we can put you in touch with customers who have successfully dealt with the problems.

brj · « **Reply #26 on:** 20 Jan 2006, 08:57 pm »

Quote from: nuforce-jason

You should switch to Satellite TV and don't use VHF TV channels.

I'd buy several NuForce amps if NuForce would start covering the cost of a full satellite TV package for me...

mdconnelly · « **Reply #27 on:** 20 Jan 2006, 09:08 pm »

Quote from: brj

Quote from: nuforce-jason
You should switch to Satellite TV and don't use VHF TV channels.

I'd buy several NuForce amps if NuForce would start covering the cost of a full satellite TV package for me...

That's in the 9.03 revision I believe

Adamay · « **Reply #28 on:** 20 Jan 2006, 10:18 pm »

My tuner is 2 feet from the Nuforces, and I have no problems whatsoever now. I use a shielded cable to the antenna, and the antenna is indoors, approximately 30 feet from the amps/tuner (I've had the antenna there for years, not in response to the Nuforce amps). Hope this helps.

rustydoglim · « **Reply #29 on:** 21 Jan 2006, 06:17 am »

Whiners

Somewhere down the road you can replace the circuit board

amplifierguru · « **Reply #30 on:** 21 Jan 2006, 07:23 am »

I trust these amplifiers are fully C-tick approved for EMR levels?
Radiated switching artefacts are a problem of the source not everything else.

Cheers,
Greg

brj · « **Reply #31 on:** 22 Jan 2006, 07:36 am »

Quote from: nuforce-jason

Whiners

Jason, what purpose does it serve to insult prospective customers?

I continue to be intrigued by the unique implementation of class D technology incorporated into NuForce amps, and everything I've read about Tran and his developments has been impressive. My admiration of clever engineering and good sound, however, are independant of my views regarding personal or corporate behavior. Personal and corporate behavior will affect where I choose to spend my money. NuForce appears to provide good sound through innovating engineering and so I congratulate NuForce on their positive reviews, but I would never pay money to a company that chooses to call prospective customers names. There are simply too many other competative products for me to reward such behavior.

Good luck in your future efforts.

bt44881 · « **Reply #32 on:** 22 Jan 2006, 12:51 pm »

I realised that once i turned on my Nuforce Ref 9, the Projector (or TV, the same results) from my DVD recorder becomes distorted, ie "raining/snowing" effect, move the power amp about 2.5 meter away, disconnect the interconnect from my Sony DVD recorder, the image improves dramatically, however once, connect back the interconnects (no "proper" interconnect of such length, make do with "normal, non-hifi grade" interconnect, the "raining/snowing" becomes worse. No so far, my own conclusions; i) the problem does not comes from power supply alone, whether the power supply contamination has an impact or not, not sure yet, ii) the problem seems affected significantly via the interconnects from the power amp to pre-amp and i suspect transfer back to the DVD recorder, the DVD recorder is not grounded in my case.... will investigate with grouding of my DVD recorder and other interconnects when i have the time .......

rustydoglim · « **Reply #33 on:** 22 Jan 2006, 01:21 pm »

Quote

Jason, what purpose does it serve to insult prospective customers?

Oh gee, can't you tell a tongue-in-cheek comment. If you have been following all my posting and have dealt with us before (oh, I forgot, you're not a customer yet), you'll know that we're the nicest and most service oriented people.

Now I am really affaid to have you as my customer. You're going to give me hell

rustydoglim · « **Reply #34 on:** 22 Jan 2006, 01:40 pm »

Ref 9 is being used in many HT setup (one customer in the bay area has 10 amps bi-amping 5 speakers). It is difficult to diagnose your problem for you (but you can post your result here) in a thread so it is best that you email support.
You should consider using a Brick Wall surge protector with good RFI/EMI shielding (do not use a power conditioner for switching amp).

We added extra grounding to the RCA in version 9.02 around early November and your Ref 9 might not have that extra ground.
Check if your Ref 9 has the following ground wiring:

Nick V · « **Reply #35 on:** 23 Jan 2006, 12:05 am »

How do you feel about non transformer-based power conditioners? I just picked up a Sound Application CF-X, do you think there would be any problems running your amps plugged into this unit?

I'm in the middle of an HT face-lift and am looking for 5 channels of amplification at the moment.

rustydoglim · « **Reply #36 on:** 23 Jan 2006, 02:03 am »

Our preamp and amp use high performance SMPS that does voltage and current regulation. It doesn't "hurt" to connect the them to a power conditioner that does the same thing. What we have found out at CES show (we tried with 3 different conditioners) tuning our system is that it sounded the best with the following setup:

Source device plug into conditioner or Brick Wall surge protector/filter
Amp & preamp directly into wall or surge protector.

The sound doesn't come through as transparent with the amp connecting to the conditioner. We speculate that it slows down the SMPS.

nuforce-casey · « **Reply #37 on:** 23 Jan 2006, 04:15 am »

Quote from: Nick V

How do you feel about non transformer-based power conditioners? I just picked up a Sound Application CF-X, do you think there would be any problems running your amps plugged into this unit?

I'm in the middle of an HT face-lift and am looking for 5 channels of amplification at the moment.

Although we have not had a chance to test Sound Application product, I do believe they are just filter and not a transformer-based design, but always start with plugging directly to wall AC as a starting and reference point.

ctviggen · « **Reply #38 on:** 23 Jan 2006, 12:29 pm »

Jason, doesn't connecting the shield to RCA ground increase the potential for a ground loop (assuming the opposite end has the shield also similarly grounded)? I've always been taught that the shield should only be grounded at one side (i.e., one component).

rustydoglim · « **Reply #39 on:** 26 Jan 2006, 07:05 pm »

That's what we thought too. But apparently for our case it worked out very well. If ground loop noise appears again in some rare cases, then it is easier to just cut off the wire.