Burson Soloist 3X Grand Tour 2023 - Teardown, personal thoughts and a few measurements

[trl]

Hello,

I recently got enough time to perform a teardown on the Burson Soloist 3X GT (2023 revised model) and I'm pleased to see very good quality electronic components inside and, of course, a different design than most other manufacturers. Although it's based on a classic A/B design, the way Burson was alternating SMPS regulators chained with Linear ones is interesting. Also, the high bias current make it one of a kind, though it's rather non-ECO and probably many folks will consider this a rather lowlight.

Then package contains the amplifier, the small shiny remote control, but also several accessories and the 5532 opamps too

Driving two headphones at both 6.3mm jack and 4-pin XLR if piece a cake

The OLED display -> Settings

Choosing between Headamp and Pre-Out, but also Sub-Out or No Sub-Out

Choosing the desired input

The blue light components are the "SP2" modules based on very low-noise linear regulators (four used on analogue parts and one for the digital parts)

Six V6 Vivid dual solid-state opamps containing

Side look

Close up with the opamps and the Panasonic relays used for In/Out operations

A look inside Burson V6 solid-state opamps

The output stage pairs of complementary 2SD2061 and 2SB1369 transistors

Backside of the output transistors

Backplate / Heatsink for the output stage transistors

The MUSES 72323 digital volume control chip

Headphones protection done around the dedicated C1237HA chip

Optical IR protection in case the top case gets open

Input / Output expansion chip PCF8574AT

The SP2 linear module created around the low noise LT3094 chip

The SP2 linear module created around the low noise LT3045 chip

Low noise Noctua fan situated on top of the amplifier board blows discretely the heat outside the case

Temperature on the case while listening to low volume

I measured on Pre-Out a SINAD of 107.4 dB vs. the 100 dB stated by the manufacturer

I measured on 4-pin Headphones-Out a SINAD of 100.2 dB vs. the 93-94 dB stated by the manufacturer
​

 

[trl]

This is really a Class A headamp, so it consumes a lot of energy. I measured 74 Watts with no music playing, although whoever is purchasing such a Class A amplifier usually cares not about how much power it consumes, especially if nearby the desk there’s a tube amp glowing that takes few times more power than this Soloist. However, I do appreciate that Burson implemented a neat Auto Power Off feature that can be activated from the Settings menu, this making the device a bit more eco friendly, even if we’re talking about a Class A amplifier.

I do like the Crossfeed feature and I'd like to see it in more headamps, so I've no idea why it's not implemented on a larger scale. The lowest Crossfeed setting is what I was using and I find that I can listen more hours without getting tired to my ears; not talking about high SPL levels, but about not getting tired of listening to music.

The amplifier is cooled down by a very silent fan (18.8 dB A-weighted) from NOCTUA, model NF-A12x25 PWM, that blows the hot air outside the case (negative air pressure) while the cold air from the room is sucked in from the bottom of the case. This way the entire PCB, which acts as a big interior heatsink for all the electronic components, and the eight powerful transistors from the output stage are getting cooled down efficiently. The top-case vents are somehow increasing the air noise with a few dB’s, but still the noise is well kept under control, especially if the distance between amplifier and the listener is 1 meter or more. However, rotating it 90 degrees, with top fan oriented backwards, will make the amplifier virtually dead silent. Also, placing the amplifier on a shelf, above ear level, will also make it virtually dead silent as well.

The Soloist amplifier has a series of protective circuits that activates and powers off the device when someone tries to operate the device with the top cover open or when the active cooling fan gets unplugged by the customer. This is a good thing to know it’s implemented, due to the fact that the heat generated by the powerful amplifier from inside, if not evacuated quickly by the Noctua fan, might quickly damage some of the electrical components inside and, of course, this will void the warranty. Of course, the amplifier is also protected against any accidental DC voltage that might occur on headphones outputs, but it could also trigger if a Silent Power module was not properly installed in its socket, grace to the dedicated circuitry designed for this around the C1237HA chip. However, I measured exactly 0 (zero) mV of DC on each channel from both jack and XLR plugs for headphones.

The power adapter outputs 24V @5A max. directly into the Soloist equipment from where a powerful MOSFET transistor, IRF5210S, that is most likely a rail splitter that delivers couple of +/-20.5V rails for the output stage, so a total of 41V RMS is used to make the eight powerful transistors to pump up the audio signal into the headphones.

The audio input stage is created around the solid-state Burson V6 Vivid dual op-amps (solid-state actually), followed by a couple of Japanese digital volume control chips MUSES 72320 that act both as volume control and pre-amp as well. Pre-amp buffer is also based on Burson V6 Vivid op-amps. When used strictly as a pre-amp, the audio signal goes into one pair of V6 Vivid opamps, then into the MUSES 72320 volume controller, then it gets to the output pair of V6 Vivid opamps.

The low-pass filter, responsible for connecting an external subwoofer, is created around NE5532 op-amps.

The above op-amps are powered by four dedicated low-noise modules manufactured by Burson and named “Silent Power”, based on the very low-noise chips LT3094 and LT3045.

The output stage is crafted around four pairs of complementary 2SD2061 and 2SB1369 transistors encapsulated in TO-220 outer shell package and able to dissipate up to 30-40W @25C case temperature, so quite a beefy output stage for a headphone amplifier. The transistors are biased with a higher current than usual, making them to operate in Class-A. Running the output stage in Class-A comes with increased power consumption (I measured about 74W with no music playing), which translates in increased temperature on the surface of the case as well. I was able to measure around 40C on the sides of the case, in a room with a rather constant 24C.

 

[Cbdb2]

This is modern technology? A HP Amp that burns 75 watts to put out a couple? How much does that bad engineering cost?

 

[trl]

@Cbdb2 you can read more about Class A amplifiers here: https://www.electronics-tutorials.ws/amplifier/amp_5.html. It's up to every manufacturer to choose their own design and their customers will decide if is worth purchasing or not.

 

[Cbdb2]

Thank you but I studied class A designs when you were 4. They typically waste 70% of the power at full output. This design wastes %7400 of the power, and needs a fan for zero advantage. Its also running the signal thru 3 opamp stages where only one is needed. Bad engineering that no one needs. And you still haven't told us how much it costs.

 

[trl]

I totally got your point, thanks for the update. The price can go up to 2.7k, but it was recently on sale for about 1.5k and their showroom devices are as low as 1.2k, so quite an expensive audio device, although its look & feel and the international warranty can be appealing for many.

 

[Cbdb2]

Ok so over priced bad engineering. Perfect audiophile gear. Theres $200 HP amps that perform better.

 

[trl]

Narrowing everything down to price/performance ratio is not what every customer is looking for, instead design, look & feel, warranty, electronic volume control, features and options and customer support might matter more for some, especially that given that above a SINAD of 90 I doubt anyone will hear any differences.

I always appreciated companies like Schiit and Burson that had the guts to come up with a completely different design for both inside and outside of their equipment, including the valve headamps from Schiit that measures rather poorly with their 0.1-0.2% THD+N. This is what others are looking for, despite of a rather inferior price/perf. ratio.

I remember when I bought my Topping A90 Discrete from a friend, he told me there's no way for him to place that small and ugly headamp in his living room due to the size and how it looks, so he sold it to me for like 2/3 of the original price. I was very happy buying it from him, given that I was looking for a top performing headamp with enough juice to power all of my cans. But this doesn't stops me owning a Burson and many other headamps made since the Objective2 era till now.

 

[Cbdb2]

All of the things you mention consumers want can be gotten at a fraction of the price, period.

 

[AnalogSteph]

You know they've got a decent margin when they can afford to put a Noctua fan in there. Mind you, at these kinds of prices...

The top-case vents are somehow increasing the air noise with a few dB’s, but still the noise is well kept under control, especially if the distance between amplifier and the listener is 1 meter or more.

They may be too restrictive or too close to the fan. You will often see often see the perforated areas over rear exhaust fans bowing outwards in newer PC cases for this reason. Anything near the rotor can cause noise as each individual fan blade is pushing along a wave of air. Even the design of fan struts is a science in itself. You may have noticed how the number of fan struts and fan blades never shares a common denominator, e.g. 4 vs. 7 or 9, and how in more modern designs the struts are also curved to be as perpendicular to the blades as possible, so the impulses generated by them passing over are stretched out to a maximum. It is essentially the same problem that contra-rotating propellers are facing to a much more severe degree.

However, rotating it 90 degrees, with top fan oriented backwards, will make the amplifier virtually dead silent.

I am not sure I get this. The unit doesn't look high enough for the fan to be place vertically...?

This fan setup reminds me of what we put in our old Topfield satellite receiver / PVR back in the day, with either 5 or 7 V tapped off from the HDD power connector. These things were super toasty stock and prone to premature failure as a result (who would have guessed).

74 W idle would run a decent 150+ Wpc AB amp. The interesting question: How much does the unit draw in standby/off? I mean, I don't see why it would not be <1 W or even <0.5 W, but still it's good to check...

 

[Cbdb2]

You know they've got a decent margin when they can afford to put a Noctua fan in there. Mind you, at these kinds of prices...

They may be too restrictive or too close to the fan. You will often see often see the perforated areas over rear exhaust fans bowing outwards in newer PC cases for this reason. Anything near the rotor can cause noise as each individual fan blade is pushing along a wave of air. Even the design of fan struts is a science in itself. You may have noticed how the number of fan struts and fan blades never shares a common denominator, e.g. 4 vs. 7 or 9, and how in more modern designs the struts are also curved to be as perpendicular to the blades as possible, so the impulses generated by them passing over are stretched out to a maximum. It is essentially the same problem that contra-rotating propellers are facing to a much more severe degree.

I am not sure I get this. The unit doesn't look high enough for the fan to be place vertically...?

This fan setup reminds me of what we put in our old Topfield satellite receiver / PVR back in the day, with either 5 or 7 V tapped off from the HDD power connector. These things were super toasty stock and prone to premature failure as a result (who would have guessed).

74 W idle would run a decent 150+ Wpc AB amp. The interesting question: How much does the unit draw in standby/off? I mean, I don't see why it would not be <1 W or even <0.5 W, but still it's good to check...

Its a headphone amp???? and it needs fans?? There something terribly wrong here.

 

[trl]

[...] I am not sure I get this. The unit doesn't look high enough for the fan to be place vertically...?

Yes, they have their own stand here: https://www.bursonaudio.com/shop/cool-stand/.

[...] The interesting question: How much does the unit draw in standby/off? I mean, I don't see why it would not be <1 W or even <0.5 W, but still it's good to check...

It's complete 0 (zero) while in stand-by and there's also an automatically stand-by as well, just in case someone forgets to power it off over night.

I do like the optical barrier they have implemented inside, so when you open up the top case (which is shiny like a glass underneath) the unit gets in stand-by/error mode instantly and it gets back only after pressing the power for about 30 sec. or if you unplug the unit from mains and replug it back after a few sec. This is a good thing because the Noctua fan is unable to properly cool off the unit with the top case open. Also, this is a good protection in case someone want to swap op-amps or voltage regulators without getting the unit off.

 

[Snoopy]

Its a headphone amp???? and it needs fans?? There something terribly wrong here.

It’s not like you will hear the fan with headphones on your head . It’s a Class A amp after all. I’m sure people purchasing this will know about all the shortcomings of such a design. 75 Watt is a lot for a headphone amp but it’s still not horrible high .. a Oled tv, gaming console and other stuff wastes more energy for „entertainment „

 

[Cbdb2]

You missed my point, or you didn't read all my posts. A class A HP Amp needs 5 watts, this unit is wasting 70 watts for no reason. Just bad engineering, like using 10 times the amount of steel to build a bridge. Besides, very few 100 watt amps need fans.