Measurement and Review of Burson Play DAC & Headphone Amplifier

[Jimster480]

I am no expert on the digital side of things but analogue volume controls rarely need "full volume" for rated output and in many traditional amps the rated power is achieved at the nominal sensitivity with the volume control well below maximum, allowing a bit of headroom for inputs with a lower output. I don't know whether this is a limitation with this product but "full volume" on a traditional amp may well be well into clipping.
It is 30 years + since I checked myself but the amp I had then went into clipping using the rated input voltage with the volume control around 1 o'clock, where the end stop was around 4 o'clock.

The issue is that they are amping the RCA outputs... So he is trying to balance the RCA output to match a level of another DAC (in this case the Topping) but if he does so, then the wave falls apart as he mentioned.

If this product used a traditional RCA output like every other product, then "volume" wouldn't be a concern and it would be left to 100% (assuming its also a pre-amp) so that it gets the cleanest output.

 

[Frank Dernie]

The issue is that they are amping the RCA outputs... So he is trying to balance the RCA output to match a level of another DAC (in this case the Topping) but if he does so, then the wave falls apart as he mentioned.

If this product used a traditional RCA output like every other product, then "volume" wouldn't be a concern and it would be left to 100% (assuming its also a pre-amp) so that it gets the cleanest output.

What do you mean?
All DACs will have an analogue amplifier after the DAC chip, surely, the variation from one to another being gain. Generally the standard output for a CD player or DAC at full modulation was 2 Volts, but plenty had different to this, not least since raising it a bit may make your product sound better on and A/B comparison in a shop, for example.
This model does seem to have more gain than others, probably for use as a preamp, but that doesn't mean that the amplifier won't be clipping into a real load on the headphone output if the volume control is set at maximum.
This doesn't surprise me one whit.

 

[Jimster480]

What do you mean?
All DACs will have an analogue amplifier after the DAC chip, surely, the variation from one to another being gain. Generally the standard output for a CD player or DAC at full modulation was 2 Volts, but plenty had different to this, not least since raising it a bit may make your product sound better on and A/B comparison in a shop, for example.
This model does seem to have more gain than others, probably for use as a preamp, but that doesn't mean that the amplifier won't be clipping into a real load on the headphone output if the volume control is set at maximum.
This doesn't surprise me one whit.

Its not a pre amp, the rca is amped. At even a volume level of 10, it would power my headphones through my o2 with the o2 volume near 8 o'clock vs normal 12 o'clock.

 

[Frank Dernie]

Its not a pre amp, the rca is amped. At even a volume level of 10, it would power my headphones through my o2 with the o2 volume near 8 o'clock vs normal 12 o'clock.

Is it not normal for the rca output to be amplified? You seem to think there is or should be, some sort of standard for volume control position versus volume from one unit to another. In my 50 years of buying kit I have become used to this not being the case, and often by a very considerable margin!

 

[Jimster480]

Is it not normal for the rca output to be amplified? You seem to think there is or should be, some sort of standard for volume control position versus volume from one unit to another. In my 50 years of buying kit I have become used to this not being the case, and often by a very considerable margin!

Yes there is usually a standard VRMS output, different DAC's have different levels. They are typically static levels, if a DAC has a pre-amp, it turns its volume down from that point. But it isn't providing current such as this. For example the DX7 does 2VRMS via SE and 4VMRS via Balanced @ 0dbfs.
This unit on the other hand provides many volts at a seriously varying rate. Additionally they usually have like 100 ohm output impedance on their RCA. I believe this unit has close to 0 ohm output impedance on its RCA jack. So it has no pre-amp functionality because there is such a strong signal going out of RCA that you can most likely damage other gear you were to plug in via RCA.

 

[Frank Dernie]

Yes there is usually a standard VRMS output, different DAC's have different levels. They are typically static levels, if a DAC has a pre-amp, it turns its volume down from that point. But it isn't providing current such as this. For example the DX7 does 2VRMS via SE and 4VMRS via Balanced @ 0dbfs.
This unit on the other hand provides many volts at a seriously varying rate. Additionally they usually have like 100 ohm output impedance on their RCA. I believe this unit has close to 0 ohm output impedance on its RCA jack. So it has no pre-amp functionality because there is such a strong signal going out of RCA that you can most likely damage other gear you were to plug in via RCA.

That is absurd. Yes, it is unconventional but most of what you write is due to your own lack of experience, sorry.

 

[RayDunzl]

Its not a pre amp

https://www.bursonaudio.com/products/play/

• "Pure Class A with no ICs on the signal path, the Play is a remote controlled preamp that teams perfectly with any power amp or active speakers."
• "Output impedance (Pre Out): 35 Ohm"
• "Outputs: RCA Pre-Amp / Headphone Jack"

Looks like Burson thinks it's a pre-amp...

I don't understand what is being argued here...

 

[Sal1950]

I don't understand what is being argued here....

Neither do I.
It is an unfortunate truth that there never has been a real standard either for a pre-outs level at WOT or from it's line level jacks.
Nor a amps input sensitivity. Not to mention impedance's.
A bugAboo we've lived with forever.

 

[Jimster480]

That is absurd. Yes, it is unconventional but most of what you write is due to your own lack of experience, sorry.

I'm not sure why you are saying such a thing.
Please let me know what other device you can find that is a DAC/Pre-Amp with a 0-ohm RCA output impedance and 6+VRMS (10 max) output on that 0-ohm impedance...

https://www.bursonaudio.com/products/play/

• "Pure Class A with no ICs on the signal path, the Play is a remote controlled preamp that teams perfectly with any power amp or active speakers."
• "Output impedance (Pre Out): 35 Ohm"
• "Outputs: RCA Pre-Amp / Headphone Jack"

Looks like Burson thinks it's a pre-amp...

I don't understand what is being argued here....

He is upset that I am saying its not actually good as a pre-amp because it is actually amplifying the RCA jacks with the same impedance as the headphone output. Effectively making it the same as plugging a 6.35mm to RCA Cable into the back of another Amp.
Taking a look at the DX7 (just for reference here) http://www.tpdz.net/en/products/dx7/index.htm -> Output Impedance on the RCA Jacks are 100 Ohm, with 2VRMS. The SMSL M8 has 2.15VRMS and the M8A with 2VRMS (I believe both have a 70 or 80 ohm output impedance).

 

[amirm]

FYI, I just got my USB linearity test working. This is still PRELIMINARY. So don't bank on it. But I think it is showing reasonable results:

At -95 dB the error is just 0.005 dB. At -100 dB though it changes to 0.169 so I went with -95 dB which results in 16 bits of resolution.

That said the error stays small until -120 dB. So I say performance is good up to about -115 dB (19 bits).

And yes, I am horrible at making graphs in Excel! So the above graph is reverse of what Audio Precision shows (left to right vs right to left).

Anyway I thought I post this to make Jim happy.

Almost forgot: the above is at 52% level which matches my other DACs output over RCA.

 

[RayDunzl]

Here's my DAC's specification, which can be and is fully intended to be utilized as a preamp.

Spoiler

Unbalanced:

Clip point:

Balanced:

Clip point:

(not sure I believe that calculation)

Headphone:

My "real" preamp is a little light on its specifications, but here goes:

And the associated (same brand) amplifier:

[\spoiler]

 

[Jimster480]

So it looks like the Analog RCA output is 30 ohms with 2VRMS? Clip point looks to be 3.6vrms?

 

[Jimster480]

FYI, I just got my USB linearity test working. This is still PRELIMINARY. So don't bank on it. But I think it is showing reasonable results:

View attachment 11022

At -95 dB the error is just 0.005 dB. At -100 dB though it changes to 0.169 so I went with -95 dB which results in 16 bits of resolution.

That said the error stays small until -120 dB. So I say performance is good up to about -115 dB (19 bits).

And yes, I am horrible at making graphs in Excel! So the above graph is reverse of what Audio Precision shows (left to right vs right to left).

Anyway I thought I post this to make Jim happy.

Almost forgot: the above is at 52% level which matches my other DACs output over RCA.

Awesome work! So at 52 on the volume dial the voltage matches?

It does show that the output is quite clean in terms of accuracy. Thanks for getting this working

 

[amirm]

Awesome work! So at 52 on the volume dial the voltage matches?

Yes, I think I was comparing it to Topping DX7 or D50. Wasn't an exact match but close.

 

[Jimster480]

Yes, I think I was comparing it to Topping DX7 or D50. Wasn't an exact match but close.

The voltage isn't the same though with the same output impedance though right?
I mean that in the sense that 2VRMS @ 100ohm output impedance isn't the same as 2VRMS @ 0 ohm output impedance.

 

[RayDunzl]

The voltage isn't the same though with the same output impedance though right?

I mean that in the sense that 2VRMS @ 100ohm output impedance isn't the same as 2VRMS @ 0 ohm output impedance.

Look to Ohm's law and a resistor divider (Voltage Source and Output Impedance, and Load Impedance) for the simple answer of where the volts go.

Are you familiar with those concepts?

If Vin = 2V
Vout (and the voltage across the load) will vary with the relative values of Z1 (output impedance) and Z2 (load).

Make the signal (Vin) AC, and the impedances can vary with frequency.

 

[Jimster480]

Look to Ohm's law and a resistor divider (Voltage Source and Output Impedance, and Load Impedance) for the simple answer of where the volts go.

Are you familiar with those concepts?

View attachment 11035

If Vin = 2V
Vout (and the voltage across the load) will vary with the relative values of Z1 (output impedance) and Z2 (load).

Make the signal (Vin) AC, and the impedances can vary with frequency.

Yes, but I am not an EE so I'd rather confirm with people who understand voltage division better than me.

The part I was confused with is not your graph, but where this falls in the line.
For example if you measure where it says "load" on your graph and its 2VRMS then that is after the output impedance on your graph....

I know from personal experience that higher output impedance = lower volume from the same source.
I just haven't ever specifically measured volts vs loudness from my amp.

 

[amirm]

The voltage isn't the same though with the same output impedance though right?
I mean that in the sense that 2VRMS @ 100ohm output impedance isn't the same as 2VRMS @ 0 ohm output impedance.

That kind of thing matters when the load impedance is small. In my case the input impedance of my measurement gear is 100 kOhm so well above any output impedance. And regardless, both are measured across the same load (i.e. 100 K).

 

[Jimster480]

That kind of thing matters when the load impedance is small. In my case the input impedance of my measurement gear is 100 kOhm so well above any output impedance. And regardless, both are measured across the same load (i.e. 100 K).

Ah alright, so it doesn't make a difference then in your testing scenario.

 

[trl]

Hello,

I see that even Pavel Macura calls his perfectly designed DISPRE headmp a "preamp", so probably BURSON's right after all.

However, after the LowPass opamps I got around 4.5V RMS and the preamp/output stage has a gain of about 2X. I managed to get through a couple of resistors connected immediately after the 3rd opamp (the LPF) a "new" RCA output signal, so I'm bypassing now the output stage to get a lower volume for the RCA plugs.

I've seen some naked pics posted for some DACs on this great forum, so I'll be posting some inside pics myself here, just in case you're interested:



It looks like there are no caps on the signal path and if using SS V4, V5 or V6 opamps from BURSON then there are no ICs too.

Best,
Raul.