Burson Soloist 3X Performance Head/Pre Amp - 8Wpc XLR with MUSE72320 volume control
Mar 14, 2021 at 9:58 PM Post #781 of 1,579

JWahl

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This is the quote from his review that I am referring to:

"The output DC-voltage is already pre-adjusted by Burson to a minimal value. After a couple of minutes of warm-up, I was able to measure values between +/-1 mV and +/-5 mV of DC, so a respectable low value indeed. However, in case you intend to swap the default opamps inside, don’t forget to measure the DC on both jack and XLR plugs before connecting headphones and adjust the blue variable resistors ONLY if the DC is higher than +/-25 mV per channel (or wait more time to warm-up or swap back the opamps with the originals from Burson)."
 
Mar 14, 2021 at 10:45 PM Post #782 of 1,579

JWahl

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After reading this, I measured the TRS output for DC with the SparkoS as per @raoultrifan's review to make sure they aren't introducing any offset. My voltmeter isn't specially calibrated and not a particularly high quality one, but I measured an amount fluctuating between -23 mV and -30 mV on the right channel and -30 mV to -40 mV on the left channel with both SparkoS. His recommendation is below 25 mV. I haven't measured the XLR output yet. It probably isn't a big deal with the insensitive HE-6SE, but IEM users using full SparkoS without adjustment may have issues. if @raoultrifan is reading this, would you care to outline the way you measured and adjusted the offset for the XLR output? I'm curious to see if that yields any subjective differences in my impressions with the SparkoS.
One more quick follow-up. I threw the V6 Vivid back in both spots and repeated the measurement on the TRS jack. I checked the right channel right after power-on and watched the measurement drop quickly with warm-up down to less than 1 mV, but repeated measurements with a few seconds in between sometimes yield different results, but all under 25 mV. I'm guessing these slow changes are just due to temperature variations over time The biggest difference I noticed though, is that with the all V6-Vivid, there isn't the constant and somewhat rapidly fluctuating DC offset like I had with the SparkoS. I'm not 100% sure what this might indicate, though. Maybe the SparkoS exposure to air makes it more sensitive to temperature changes? I'm probably overthinking it, though.
 
Mar 15, 2021 at 1:28 AM Post #784 of 1,579

raoultrifan

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if @raoultrifan is reading this, would you care to outline the way you measured and adjusted the offset for the XLR output?
If speaking about headphones out, then ideally would be to keep the DC below 3mV when feeding 16-32 Ohms headphones (especially IEMs) and below 15-30,V if feeding hard to drive planars or high impedance cans. There are four blue DC adjust potentiometers on the board, but needs lot of care and attention to set them correctly; you need to measure all four headphones outputs from the balanced XLR-plug to set them up well (each pot. is adjusting DC for all 4 hot wires; there is no reference to GND there).
 
Mar 15, 2021 at 6:54 AM Post #785 of 1,579

JCANs

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Hello all,

So in my current search for a new amp (mostly to drive my ZMF Aeolus, sourced from RME), I value safety a lot (overvoltage, shorting, etc.).
Especially the protection for the headphone output is a must for me. How does the Soloist compare in this regard?
So far my eye caught the new Violectric amps (380, 550, 590) that do have nice safety implementations, but the Soloist being only half of the price also seems interesting.
Anyone familiar with the safety implementations of the Burson? :)

Thanks!
 
Mar 15, 2021 at 7:05 AM Post #786 of 1,579

Sam Spade

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If speaking about headphones out, then ideally would be to keep the DC below 3mV when feeding 16-32 Ohms headphones (especially IEMs) and below 15-30,V if feeding hard to drive planars or high impedance cans. There are four blue DC adjust potentiometers on the board, but needs lot of care and attention to set them correctly; you need to measure all four headphones outputs from the balanced XLR-plug to set them up well (each pot. is adjusting DC for all 4 hot wires; there is no reference to GND there).
@JWahl and @raoultrifan an so is what you two are saying is that swapping op amps in and out isn't just plug and play you need to adjust potentiometers and check voltages and do stuff that an electronics expert understands better than a biologist like me?

Burson do imply it is plug and play even with other brands

Note I did get some sparko Pros in my Conductor 3X ref as proof of concept. It sounded noticeably better. Now I'm working on a solution that allows me to put the lid back on and avoids shorting anything out.
 

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Mar 15, 2021 at 7:15 AM Post #787 of 1,579

Sam Spade

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Also that was just the LP stage, i'm going to try and fit the IV stage too. Andrew Sparko suggested changing all 4. Interestingly, Burson advised me to leave the vivids in the IV stage and try the classics in the LP stage. It looks like I'm going to be able to get the Sparko pros into the LP stage safely.

If I can't fit the sparko pros x 4 in I'll try the sparko SS3602 Dual Discrete Op Amp in the IV stage. and mix and match with the bursons and see what result is best.

 

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Mar 15, 2021 at 8:14 AM Post #788 of 1,579

MakubexGB

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Hello all,

So in my current search for a new amp (mostly to drive my ZMF Aeolus, sourced from RME), I value safety a lot (overvoltage, shorting, etc.).
Especially the protection for the headphone output is a must for me. How does the Soloist compare in this regard?
So far my eye caught the new Violectric amps (380, 550, 590) that do have nice safety implementations, but the Soloist being only half of the price also seems interesting.
Anyone familiar with the safety implementations of the Burson? :)

Thanks!
The more knowledgeable can provide more information but one thing I can tell you is that Burson boasts reverse voltage protection on the stock V6 opamps included in the Soloist 3XP.
 
Mar 15, 2021 at 8:34 AM Post #789 of 1,579

raoultrifan

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@JWahl and @raoultrifan an so is what you two are saying is that swapping op amps in and out isn't just plug and play you need to adjust potentiometers and check voltages and do stuff that an electronics expert understands better than a biologist like me?
In most amplifiers is the same: DC voltage on outputs will easily change after swapping opamps, especially if not using manufacturer recommended opamps. In most cases you won't need to adjust anything, but sometimes the output DC might be too high to accommodate low impedance headphones and a bit of adjustment should resolve this.
 
Mar 15, 2021 at 9:31 AM Post #791 of 1,579

JWahl

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If speaking about headphones out, then ideally would be to keep the DC below 3mV when feeding 16-32 Ohms headphones (especially IEMs) and below 15-30,V if feeding hard to drive planars or high impedance cans. There are four blue DC adjust potentiometers on the board, but needs lot of care and attention to set them correctly; you need to measure all four headphones outputs from the balanced XLR-plug to set them up well (each pot. is adjusting DC for all 4 hot wires; there is no reference to GND there).

Thanks for the reply. What I am uncertain of, is which XLR pins I need to measure across. Do I just measure across the positive and negative phase pins for each channel and then adjust the respective potentiometers while measuring? The TRS output is pretty straightforward being ground to hot.

EDIT: I just re-read the last part and think I understand. Would I just use the chassis ground to reference the measurement for each xlr pin?

@JWahl and @raoultrifan an so is what you two are saying is that swapping op amps in and out isn't just plug and play you need to adjust potentiometers and check voltages and do stuff that an electronics expert understands better than a biologist like me?

Burson do imply it is plug and play even with other brands

Note I did get some sparko Pros in my Conductor 3X ref as proof of concept. It sounded noticeably better. Now I'm working on a solution that allows me to put the lid back on and avoids shorting anything out.
It's never truly plug an play from an electronics perspective, since a circuit is typically designed around the parameters of an op-amp. I think Burson assumes that if someone is swapping op-amps with ones they don't manufacture, that the user has a certain level of technical experience or knowledge. That being said, the Soloist should be designed at least that typical audio op-amps aren't going to produce enough offset to damage the headphones (or so I would hope). As insensitive as the HE6-SE is, that measured amount probably isn't audible with that headphone. I didn't bother to measure it before because I didn't notice an audible problem on its own. With higher levels of DC offset, it could begin to produce audible distortion. This is likely one of the reasons amps like these sound a little harsher when they're first powered on versus once the temperature has stabilized; the offset is temperature dependent. With the SparkoS being exposed to air (versus being in a plastic case) they likely cool faster, which may be causing that more rapid fluctuation due to compensation. I hate to admit this, but although I'm in my senior year of an EE degree, I am by no means an expert on analog circuits, and I'm still learning as I go. Part of me is digging into this is purely for academic curiosity, so to speak.

From what I've read on the topic, there's debate about at what point the offset becomes an audible problem, thus the values provided are more rules of thumb. In certain rare cases, like amplifiers that have line-level signal transformers, even small amounts of DC present at the transformer can cause the core to saturate, producing audible and unpleasant distortion (that's not the case here). If it doesn't sound audibly unusually bad to you, and you don't feel comfortable messing with the technical aspects, it's probably just best to ignore it and enjoy the music.
 
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Mar 15, 2021 at 10:03 AM Post #792 of 1,579

raoultrifan

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Do I just measure across the positive and negative phase pins for each channel and then adjust the respective potentiometers while measuring?
Exactly! The 6.3mm jack output (TRS) will also be adjusted as well, after the XLR 4-pin will be adjusted by you first.
Would I just use the chassis ground to reference the measurement for each xlr pin?
No, as you said above: between V+ and V- of each channel (pins 1 & 2, then pins 3 & 4). Maybe you won't need to adjust anything, do a measurement first (no music playing, no input cables connected, volume to the min.).
 
Mar 15, 2021 at 2:48 PM Post #793 of 1,579

Hamlap

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I think they pair very well. Right now I'm running the Soloist 3XP stock, that's all Vivid opamps, so the sound is mostly transparent. It allows the VC to show off its wide soundstage. I say "mostly" transparent because if the Topping A90 is supposed to be "completely" transparent then there are minor differences. Most noticeably to me is that the A90 would be more "in your face", as in it sounded like it brought more of the sounds in a track forward to the same layer. With the 3XP it sounds to me like there's more layering, which can make some sounds/instruments that I was used to hearing louder sound a little more distant. The mids, especially upper mids, sound more forward in comparison. Depending on the song it can be a pro or a con. This can give the perception of an even bigger soundstage, and I love me a huge soundstage, but also sometimes I find myself raising the volume even more because I want to hear those distant sounds with more impact which can then make the highs a bit fatiguing.

I also have a pair of V6 Classics and a pair of Sparko opamps that I need to play around with and see what's my favorite combination.
The Soloist 3XP came in today. Love the build and it sound great (from my hour of listening). Thanks for helping me!
 
Mar 15, 2021 at 6:19 PM Post #795 of 1,579

Bazaar

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Where'd you get it? Brand? I'm pretty much running XLR balanced to my cans, but don't have that cable for my 660S.
 

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