[QQrydza]

raoultrifan thanks for detailed explanation. [EDIT] Looked closer and on schematic you posted it looks that each channel use single DUAL opamp. Is it the same in Burson design? Did they make a mistake in Manual saying there is there are 2 Dual LP and 1 Dual I/V?
Can you "ring" the lines from DAC to amps to confirm how they are configured?

[EDIT] Image deleted to not mislead anyone

kebcy since my last post it's radio silence from Burson

 

[raoultrifan]

@QQrydza, I believe it's wrong what you've painted in red. The ES9018 recommended design from above should be fine actually, but the first stage after the DAC would be the input-voltage converter stage, followed by the active low-pass filter for the RCA ouptuts and the passive LPF for the XLR outputs.

 

[QQrydza]

@QQrydza, I believe it's wrong what you've painted in red. The ES9018 recommended design from above should be fine actually, but the first stage after the DAC would be the input-voltage converter stage, followed by the active low-pass filter for the RCA ouptuts and the passive LPF for the XLR outputs.

I was thinking the same way but i also wanted to put schematic that you've posted into fact that in manual they state to have 2x DUAL LP (one for each channel?) and 1x DUAL I/V that's why red squares seems logical this way.
Can you check real connections on the device?

Other possible scenario is that U1 and U2 are from LP Dual opamp(one for each channel or splitted per Left/Right so one Dual LP is [U1 Left and U1 Right] and second DUAL LP is [U2 Left and U2 Right]) and U3 is shared between Left and Right for I/V.
This would create not balanced XLR output (when used different opamps in LP and I/V stage) but it does not matter for play since there are no XLR output. On the other hand this allows you to change "sound signature" with one opamp change.

 

[raoultrifan]

LPF can also change the sound flavor. I strongly recommend you identical opamps in those 3 DIP8 sockets.

 

[raoultrifan]

[...]
Can you check real connections on the device? [...]

Not sure what do you mean, but ostewart did a nice close-up/macro here: https://cdn.head-fi.org/a/10014852.jpg.

 

[QQrydza]

Not sure what do you mean, but ostewart did a nice close-up/macro here: https://cdn.head-fi.org/a/10014852.jpg.

I was thinking about checking electrical connection with DMM between DAC and Opamps to determine the schematic from your earlier post.
I'm pretty sure that they've split each DUAL to left/right channel to give most versatility but it would be good to prove it.
I also completely agree that LP filter has impact on sound/audio dynamics, nonetheless I think you can agree that I/V has most impact.

 

[raoultrifan]

Each dual opamp is dedicated to each channel, indeed, like stated in one of my previous posts. Everything was don by the book, according to ESS design recommendation, just opamps might differ.

On every DAC the I/V stage is the most important one; this is why some replaces the I/V opamps with low-noise resistors (10-ohms for example) or by expensive transformers, then uses active or passive LPF. However, this means to dramatically decrease the output voltage, so this is usually done to DIY kits per EE instructions and not inside the PLAY.

 

[QQrydza]

Each dual opamp is dedicated to each channel, indeed, like stated in one of my previous posts. Everything was don by the book, according to ESS design recommendation, just opamps might differ.

If that's the case I am just confused by the naming from manual. In manual they show 2x DUAL LP (which would be U1 and U2 from schematic for each channel) and then U3 would be I/V that's split between right/left channel?
I am not an expert in audio(I am electronic engineer by trade, but doing mostly digital stuff and C embedded programming) but it would be more logical for me if the split each of DUAL amp for channel.
This way we would have DUAL LP (having U1 for left and right channel), DUAL LP (having U2 for left and right channel), and DUAL I/V same as stated above. This way you have most versatility of switching and also you ensure that both channels will play with same characteristic - even if you put different DUAL opamps in each slot (LP | I/V | LP).

Looking closer on pic you've linked I've seen something concerning.

Soldering like this should never pass QA (assuming board was not modded/resoldered by someone).
Excessive amount of solder causing balls at the end of pins, what is worse even balls BETWEEN the pins that might couse a short. Could be easily fixed by:
1. Bigger pads on PCB to accomodate solder and also make accesing pins easier (would require PCB change).
2. Stencil correction by making smaller holes for solder to pass through or making whole stencil with thinner metal sheet (easy fix on assembly end - does not require PCB changes).
I know that it does not concern audio, just throwing my 2 cents.
Anyway this flaw could've been coused by someone modding the device or resoldering chip. If it was like that from production it might have been spotted and fixed with new revision

 

[Oscar-HiFi]

If that's the case I am just confused by the naming from manual. In manual they show 2x DUAL LP (which would be U1 and U2 from schematic for each channel) and then U3 would be I/V that's split between right/left channel?
I am not an expert in audio(I am electronic engineer by trade, but doing mostly digital stuff and C embedded programming) but it would be more logical for me if the split each of DUAL amp for channel.
This way we would have DUAL LP (having U1 for left and right channel), DUAL LP (having U2 for left and right channel), and DUAL I/V same as stated above. This way you have most versatility of switching and also you ensure that both channels will play with same characteristic - even if you put different DUAL opamps in each slot (LP | I/V | LP).

Looking closer on pic you've linked I've seen something concerning.

Soldering like this should never pass QA (assuming board was not modded/resoldered by someone).
Excessive amount of solder causing balls at the end of pins, what is worse even balls BETWEEN the pins that might couse a short. Could be easily fixed by:
1. Bigger pads on PCB to accomodate solder and also make accesing pins easier (would require PCB change).
2. Stencil correction by making smaller holes for solder to pass through or making whole stencil with thinner metal sheet (easy fix on assembly end - does not require PCB changes).
I know that it does not concern audio, just throwing my 2 cents.
Anyway this flaw could've been coused by someone modding the device or resoldering chip. If it was like that from production it might have been spotted and fixed with new revision

This was a pre-production unit, not the final revision.

 

[up late]

If that's the case I am just confused by the naming from manual. In manual they show 2x DUAL LP (which would be U1 and U2 from schematic for each channel) and then U3 would be I/V that's split between right/left channel?
I am not an expert in audio(I am electronic engineer by trade, but doing mostly digital stuff and C embedded programming) but it would be more logical for me if the split each of DUAL amp for channel.
This way we would have DUAL LP (having U1 for left and right channel), DUAL LP (having U2 for left and right channel), and DUAL I/V same as stated above. This way you have most versatility of switching and also you ensure that both channels will play with same characteristic - even if you put different DUAL opamps in each slot (LP | I/V | LP).

Looking closer on pic you've linked I've seen something concerning.

Soldering like this should never pass QA (assuming board was not modded/resoldered by someone).
Excessive amount of solder causing balls at the end of pins, what is worse even balls BETWEEN the pins that might couse a short. Could be easily fixed by:
1. Bigger pads on PCB to accomodate solder and also make accesing pins easier (would require PCB change).
2. Stencil correction by making smaller holes for solder to pass through or making whole stencil with thinner metal sheet (easy fix on assembly end - does not require PCB changes).
I know that it does not concern audio, just throwing my 2 cents.
Anyway this flaw could've been coused by someone modding the device or resoldering chip. If it was like that from production it might have been spotted and fixed with new revision

burson audio has been around for more than twenty years. the build quality of its products has been lauded by reviewers and owners alike, and they're backed by a five year warranty. i think they might know what they're doing.

 

[QQrydza]

burson audio has been around for more than twenty years. the build quality of its products has been lauded by reviewers and owners alike, and they're backed by a five year warranty. i think they might know what they're doing.

I never doubted that, just stated what I've noticed

 

[up late]

never?

 

[QQrydza]

Ye, that's why I wrote "flaw could've been coused by someone modding the device or resoldering chip" since I wouldn't believe this soldering would pass Q/A.
And as for a pre-production device, I've designed plenty of boards that had flaws like that, yet still worked

 

[up late]

no worries then

 

[raoultrifan]

If that's the case I am just confused by the naming from manual. In manual they show 2x DUAL LP (which would be U1 and U2 from schematic for each channel) and then U3 would be I/V that's split between right/left channel?
I am not an expert in audio(I am electronic engineer by trade, but doing mostly digital stuff and C embedded programming) but it would be more logical for me if the split each of DUAL amp for channel.
This way we would have DUAL LP (having U1 for left and right channel), DUAL LP (having U2 for left and right channel), and DUAL I/V same as stated above. This way you have most versatility of switching and also you ensure that both channels will play with same characteristic - even if you put different DUAL opamps in each slot (LP | I/V | LP).
[...]

Hello,

I'm sure that the design was done in respect with ESS recommendations published already in one of my previous posts. Each DAC channel's I/V is connected to one dual opamp, in a balanced manner, then aggregated into the active LPF created by a 3rd dual-opamp. This way we can get the lowest THD possible out of this DAC chip and the highest dynamic. What's written on that flyer it's not my concern, thanks for understanding.

Honestly, I would not worry much about the PCB design or about the soldering done on a pre-production/alpha-testing unit. Feel free to check the pics Ive posted on my review here: https://www.head-fi.org/showcase/burson-play.22702/reviews#review-19746. ES9018K2M is perfectly soldered and all the components around as well. Also, have a look to the backside of the PCB and the ground plane...quite well done I'd say.

Best,
Raul.

P.S.: Before publishing my review I've done extensive tests to my unit and besides the IEM noise everyone else is aware of, I found no other functional issues. The device survived perfectly, even when square-waves signal were applied directly to PCB-inputs and no significant roll-of was found from 10 Hz to 100kHz. I can only recommend this combo for it's design, sturdiness and audio quality.