Review and Measurements of NuForce STA-200 Power Amp

[amirm]

Why is this not used all of the time then?

Patents would be one reason. Quad for example popularized the so called "current dumping" method but they patented it so others could not easily follow.

 

[amirm]

All in all, I can see a $299 maximum retail as being reasonable, but at $1299, it's utter theft.

I couldn't sell just the case for $299 and still stay in business. From what I can tell, the unit is always on sale for $499 so the $1299 is just a random number they put out there.

 

[amirm]

Glad to see amps receiving the same level of scrutiny as DACs. Next frontier should be AVR's...

It is a challenging category due to size and weight of these units. Shipping them back and forth will be expensive so I don't expect to be able to test larger number of units unless manufacturers loan gears.

I do have a few AVRs I bought 10 years back so I could test them. But testing more of them would be hard due to logistics.

I also have a few more amps that I have here. I will probably review the Behringer A500 next.

 

[amirm]

@amirm I see Grados on a measurement rig in the background of your photo. Is this a hint of things to come?

That was the original plan. But so far, I am not seeing good value in publishing measurements of headphones due to high variability.

 

[restorer-john]

Can shielding prevent/mitigate this issue?

It can help of course, but based on the photos, they already have acknowledged there may be an issue. Notice the input RCAs are insulated from the chassis and there are resistors (probably 10+ ohms or so) tacked from the RCA shell outer down to OV (near the screws).

This was common practice when trying to keep noise out of front ends from chassis eddy currents etc. Problem is, those low value resistors can vaporize in certain situations and leave the RCA jack outer with no ground reference.

 

[Blumlein 88]

Glad to see amps receiving the same level of scrutiny as DACs. Next frontier should be AVR's...

I'd like to see some of that too. I've posted a couple reviews of AV pre/pro's. They are somewhat recent though not up to date models. I can see the problem doing such measurements for Amir however.

 

[Blumlein 88]

These pictures below I found on the internet show internals. There appears to be several versions and cable dress changes between them. There also appears to be dual vs single transformer (perhaps a deluxe higher powered version) and ones with half the number of driver and output devices populating the PCB, discrete paralleled diode bridges and monolithic bridges in other images.

If the photos below are an accurate representation of the unit you tested, I would certainly expect wild variations between the channels with transformer/psu induced harmonics due to the proximity of the input cabling and the mains/transformer wiring. The right channel would logically be the worse performer based on the photographs.

View attachment 17068

View attachment 17069

View attachment 17070

All in all, I can see a $299 maximum retail as being reasonable, but at $1299, it's utter theft.

I see they are using RG 142 b/u input wiring.
https://www.pasternack.com/images/ProductPDF/RG142B-U.pdf
I've used it before. Silver clad solid core steel center conductor and teflon insulation with silver braided shielding or some versions have silver clad copper braid. That is very stiff wire.

 

[graz_lag]

I have been looking forward to you reviewing a NuForce product since I have known that they were shit since NwAvGuy measured one of their DAC/amps a long time ago and they defended it by saying that they "design by ear."

http://nwavguy.blogspot.com/search?q=nuforce

shit or Schiit ? I'm new on this forum, I live in France so pls. excuse any mistake in the grammar ...

 

[Dialectic]

This amplifier appears to use the JOB circuit invented by Goldmund. Perhaps that circuit is not all it's cracked up to be.

 

[oliveoilthansnakeoil]

This amplifier appears to use the JOB circuit invented by Goldmund. Perhaps that circuit is not all it's cracked up to be.

Is JOB Goldmund's little company? Someone say they are not relevant, and other people say it's like OEM. What is exact?

 

[oliveoilthansnakeoil]

JOB is Goldmund's amplifier circuit, and Goldmund sells surplus amplifier modules in the unusual-looking JOB cases at a massive discount to Goldmund amplifiers.

http://www.jobsys.com/
So they are same company group....? It looks american company in LA.

 

[Frank Dernie]

Is JOB Goldmund's little company? Someone say they are not relevant, and other people say it's like OEM. What is exact?

Job is a Swiss company that Goldmund bought back in the mid 1990s in order to obtain their patented power amp circuit.
Job produced a pro power amp with a single input and 10 turn volume potentiometer back then.
Goldmund kept Job going as their pro arm and slowly merged their product lines in terms of circuit boards.
Currently the Job circuit boards are similar, if not identical to, the Goldmund ones but in a much cheaper case and often with a smaller power supply.
I bought Goldmund Mimesis 29.4 monos in around 1996 iirc which may be the first Goldmund products to use the Job circuit.
I also have the Job Pre, 225 power amp and also the Integrated, which has a DAC with USB and SPDIF inputs and a single analogue input which I use a lot.
The Job products are sold in US$ on an American web site but shipped from the Goldmund factory in Switzerland.

 

[Frank Dernie]

JOB is Goldmund's amplifier circuit, and Goldmund sells surplus amplifier modules in the unusual-looking JOB cases at a massive discount to Goldmund amplifiers. They tout extremely wide bandwidth, but my JOB 225 amplifier had issues with various kinds of noise. I sold it at a small loss.

Interesting. My Goldmund Mimesis 29.4 monos had a bit of noise into my Epilog 1&2s, only audible with no music playing, but both my Pre/225 and the Job INTegrated are completely quiet. I can -just- hear slight noise from my 105dB/watt Tune Audio Animas with my head inside the mid range horn
For me the biggest limitation of the 225 is its way higher than average gain, making it all but unusable with any preamp other than their matching one.

 

[Frank Dernie]

This amplifier appears to use the JOB circuit invented by Goldmund. Perhaps that circuit is not all it's cracked up to be.

Where did you find that info?
Looking at pictures I see similarities to the Job225 pcb layout but lots of differences.
It is nothing like the other Job circuit boards I have seen.

 

[Dialectic]

Interesting. My Goldmund Mimesis 29.4 monos had a bit of noise into my Epilog 1&2s, only audible with no music playing, but both my Pre/225 and the Job INTegrated are completely quiet. I can -just- hear slight noise from my 105dB/watt Tune Audio Animas with my head inside the mid range horn
For me the biggest limitation of the 225 is its way higher than average gain, making it all but unusable with any preamp other than their matching one.

I believe the Mimesis amplifiers used a different circuit, with the JOB circuit (in its various iterations) appearing only in the later Telos and Metis amplifiers and in Goldmund's active speakers.

I used the 225 with the Mytek 192 DSD as preamplifier. It always had a bit of hiss (including through insensitive Genesis and KEF speakers) and had a ground loop problem that Goldmund kindly fixed at their expense.

 

[Dialectic]

Where did you find that info?
Looking at pictures I see similarities to the Job225 pcb layout but lots of differences.
It is nothing like the other Job circuit boards I have seen.

I saw the similarities, and my impression is confirmed here:

http://www.theabsolutesound.com/articles/optoma-nuforce-sta200-power-amplifier/

 

[Frank Dernie]

I saw the similarities, and my impression is confirmed here:

http://www.theabsolutesound.com/articles/optoma-nuforce-sta200-power-amplifier/

Thanks.
I tried a Chord Hugo and a Beresford Caiman 2 DAC as "preamps" but they were both poor matches so I ended up getting the matching preamp and using the DAC's fixed output. Currently I am using the Integrated for CD and FM tuner.

 

[Frank Dernie]

I

I switched to a Devialet 120 in my second system, and I've been pleased with the improvement over the JOB, which has been substantial.

I must have cloth ears! I used the Job Pre/225 whilst my Devialet Original d'Ateliers were being updated to Core Audio spec and I didn't notice a particular difference in sound, though the Job is more limited for inputs and I detest using up/down volume buttons on remotes so was delighted when the Devialets got back!

 

[Dialectic]

I must have cloth ears! I used the Job Pre/225 whilst my Devialet Original d'Ateliers were being updated to Core Audio spec and I didn't notice a particular difference in sound, though the Job is more limited for inputs and I detest using up/down volume buttons on remotes so was delighted when the Devialets got back!

I like the extremely low noise floor of the Devialet, as well as the SAM feature, which is wonderful for minimonitors in nearfield setups.

 

[amirm]

I looked at Job 225 specs/website before finishing this review. They show the same poor distortion metrics as I got/NuForce advertises. So they are no better in this regard.