Dussun R30 "Hyper Class A" amplifier

[stax fart]

I was very tempted to buy Audio GD Master 10 integrated amplifier, I know that Audio GD makes incredible stuff at low prices, Master 10 is 250w/8ohm in class A/B...but, searching in the web, I found this integrated amplifier:

Dussun R30

This is the description and specifications of the amplifier:

The R30  beside others in its design offers the following highlights: High precise volume control in 0.1dB steps with left and right channel fine-synchronized: Considering the volume control device is one of the souls of an amplifier, R30 employes a DUSSUN- developed volume control device, which set up by a 16-bit performance, digital controlled analogue circuit and possesses 1/65,535 level superfine resolution within whole volume control range. This volume control comprising circuit high linear solid state switch and precision resistors, ensures precise synchronization of R30's left and right channel volume control at any position within its 80 dB volume control range. It practically eliminates all the problems such as  sound quality degradation, application intervention from frequency and phase distortion, volume synchronization errors, sliding friction noise, limited lifetime attribute of traditional volume control potentiometers, various voltage ratio, and so on. No matter whether working principle or practical performance, as a fact the R30 reached the highest technical level fully among the state of the art hi-end amplifier volume control and takes part  "Club of 0.1 dB volume control'. Power output stage with low distortion, non-feedback at power output terminal: The new designed "Optimized Self-Adaptive Bias Circuit", much different from routine design where output stage feedback always leads to large non-linear distortion especial at high frequency side, improves significantly linearity in output stage signal crossover region, while maintaining large power output without switch distortion. By adopting this system R30 accomplished super low crossover distortion. Along with the most nature and spacious tone from a "non-feedback at output terminal amplifier'', R30 achieved the perfect result of full power output, low distortion, high sound quality in whole audio frequency. Thorough independent dual-mono channel design: R30 left and right channel circuit as well as control units are equipped with individual independent power supply systems. Data used to control individual channel is transmitted optically. Absolute electric isolation made R30 is true to its name, dual mono channel amplifier, working same as two sets of precisely synchronized independent mono channel amplifiers, with nil stereo crossover between left and right channel, resulting in pinpoint accurate sound images. Strong control and pre-set functions, such as: Individually pre-set gain level for all input terminals Individually pre-set channel name for all input terminals Display screen brightness adjustable for 4 levels Maximum volume pre-set to protect expensive loudspeakers Fade-in volume when switching on Aluminum full function remote control unit

About "Hyper Class A"

The "Hyper Class A" is a "Green" Class A solution, whose technically successful adaptive-bias circuit achieves the extra-large class A power output objective under conditions of low-power consumption and low heat producing. The adaptive-bias circuit with an ideal specification permits the amplifier to maintain class A mode output even if the speakers 'impedance drops largely and output power increases several times. This situation is different from the traditional pure class A amplifiers' inevitable situation of returning to class B when the speaker load impedance goes down, and is much close to the ideal class A amplifier essence.

Technical Data
No. of Input Groups RCA: No. of Input Groups XLR: Input Impedance: Voltage Gain: Gain Resolution: Volume Control Range: Line Out / Recording Output: Rated Output: Frequency Range: THD + Noise:  S/N Ratio: Output Impedance: Remote Control: Power Consumption: Power Supply: Environment Temperature: Enclosure:  Color: Dimensions: Shipping Weight:	4 2 50 kΩ 6, 12 or 18 dB in line stage 0.1 dB steps above 31 in display (-50,0 dB) 80.0 dB 1 2x200W at 8Ω Class A, 2x 360W at 4Ω, Class A 20Hz-20kHz ± 0.5dB ≤ 0.3% ≥ 105 dB, A-weighted ≤ 0.07Ω, A weighted Infrared, in alumina enclosure 1500 VA max. A/C 110V/60Hz, 220±10 V / 50-60 Hz 0-40°C Aluminum Black-Silver 440x197x500 mm, WxHxD 36.5 kg approx.

 

Now, price is 2975€ / 3225usd

I'm not an expert in amplification, I'm looking for an integrated amp so please, to the people in the forum with knowloedge, is this the bargain of the century or too good to be true?

2x200W at 8ohm, all in class A (wtf!!!)

Edited September 21, 2016 by stax fart

[skullguise]

Don't know about this specific amp, but the Dussun amps that Mark Levinson (the man) imported as Red Rose - and bumped up the cost pretty big - got some nice reviews overall.

I think it's funny that THIS amp looks kind of like Mark Levinson (the post-man-company) products....

I would bet this is very good, but without real-world info it's tough to jump right in.

Edited September 21, 2016 by skullguise

[swt61]

I did not know that Levinson employed imported amps. That's rather disappointing to know. 

[spritzer]

It was Levinson back in the late 90's (not the company by the same name) with Red Rose Music.  Bunch of amps and speakers all sold for silly prices while actually being rebranded stuff from China.  His new company is more along the lines of Cello though. 

As for this amp, it could be good but a marketing blurb tells us nothing.  I've got the "JC-3" clone from China and it is pretty good for the money. 

[RudeWolf]

I've heard nothing but bad rep about these bias changing class-A amps. Used to be all the rage in eighties.

[mypasswordis]

If done right there is nothing bad about it. Krell uses something they call iBias in their new amps, and I'm working on implementing my own version right now (not knowing anything about what they did, other than whatever they mention on their site).

Gotta love 65000 discrete volume settings

[swt61]

The Cello stuff was amazing. The Palette specifically.

[skullguise]

Krell's first foray into variable bias, Sustained Plateau Bias, was a fucking horror show.  I traded in a fantastic KSA-50 Mk II (with confirmed boards from KSA-100 as they were close to end of manufacturer life, so shared some parts), and got the KSA-50S.  BIG drop in sound quality, had major seller's remorse on that one.

They got it better in later lines, but that first one sucked.  I'd hope others like Dussun wouldn't make similar mistakes.

[mypasswordis]

If you have the chance to listen to a new Krell with iBias, I'd be interested in your impressions. Especially since these were probably developed after the D'Agostinos were ousted from the company.

Check out this pic from Dan D'Agostino's new high-end company, especially the huge heatsink difference between the new and old (KSA-250):

 

 

 

Edited September 22, 2016 by mypasswordis

[Craig Sawyers]

2 hours ago, skullguise said:

Krell's first foray into variable bias, Sustained Plateau Bias, was a fucking horror show.  I traded in a fantastic KSA-50 Mk II (with confirmed boards from KSA-100 as they were close to end of manufacturer life, so shared some parts), and got the KSA-50S.  BIG drop in sound quality, had major seller's remorse on that one.

They got it better in later lines, but that first one sucked.  I'd hope others like Dussun wouldn't make similar mistakes.

One of the reasons Krell went with variable bias was that the sustained Class A beasts (KSA50, KSA100, KMA100 etc) ate power transistors. Krell rebranded them Krell A and Krell AA to hide what the real part was (in the same way Audio Research ground off the part number of transistors and painted on a three colour code). My KSA100 blew three times, in a final last gasp taking out the drivers and their emitter resistors to the extent they burnt part way though the board. This was typical of the entire series. So variable bias was introduced, not from some kind of green reasoning, but to mitigate self immolation tendencies.

[RudeWolf]

10 hours ago, mypasswordis said:

If done right there is nothing bad about it.

Well, you could say the same about Class AB and maybe even Class D. Even classic Class A doesn't guarantee anything, unless it's done right.

[Hopstretch]

"Does it sound good?"

"No, it Dussun."

[emoji322]

[johnwmclean]

 

Edited September 22, 2016 by johnwmclean

[Craig Sawyers]

On 9/21/2016 at 10:48 PM, swt61 said:

The Cello stuff was amazing. The Palette specifically.

Found this lurking on my PC

CELLO_AUDIO_PALETTE (1).pdf