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Twisted Pear Audio - Buffalo32S (ES9018 DAC)

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The problem is the very low impedance of polymer caps, it can sometimes cause LM317/337 stability problems on their output
Somebody also hinted to me polymer is best left to digital decoupling, it seems these caps are better at higher frequencies than at low frequencies making them less suited to analogue circuits.
How true this is I'm not sure yet, its something I'm reading up on at the moment to satisfy curiousity

Edit
To answer the last question, no I've not yet replaced the SVP's , they sound much better to my ears since I fitted the discrete PH shunt regs

I can't guarantee replacing these caps is going to solve peoples problem with the sound though, its mainly just an idea and might be worth trying.
Also this is not to say the LM317/337 regs are a problem for everybody, I 'm just posting from my experience so far;)

IMHO LM317/337 are fine to start you off as a simple,convenient cheap means of regulation, theres certainly way better performance alternatives to be had though although more expensive
 
Duffy Moon said:
Can someone with an electronics/physics background explain to me (or point me in the right direction to) the science behind 'burn-in' please.
Also, does it make a difference whether the input is I2S or SPDIF and if so, why?


Javin5 said:


I agree, tricky question. Burn-in is extensively used in military, space and medical electronics to catch early defects of components, not because the characteristics or performance of the system or its components has to settle in. It would be entirely unacceptable if such electronics would have to be switched on for days before it would perform to the fullest. Burn-in for reliabilty reasons (weeding out infant mortality) has been thoroughly investigated and is well documented. Burning in cables? No science behind that one.

...


Yeah, basically to catch infant mortality. Electronics are powered up, sometimes in oven to weed out marginal parts.

But the semiconductor industry has gotten so good that burn-in is only done is critical applications like life support, military or space applications. Commercially, if something dies, you return it. much cheaper than burn-in.

In audio, I think burn-in happens inside your ear :).
 
scanspeakman said:
oh boy.....after reading all these (positive) review I am getting more and more frustrated every day that my buffalo32s still hasn't arrived. The package is still stuck/missing somewhere in the customs procedure..............

Scanspeakman


Hi Scanspeakman,

Mine were in customs May 15th and out of customs May 27th (also Holland).

No charges btw.
 
leo said:
The problem is the very low impedance of polymer caps, it can sometimes cause LM317/337 stability problems on their output
Somebody also hinted to me polymer is best left to digital decoupling


Hi Leo, the LCBPS and the BUF32S rails has been scoped with absolutely no hint of stability issues with driving low impedance caps. Low impedance is exactly what you want. :)

If it were truly a cause of stability issues you would never see film or ceramic caps after LM317/337s, and they are quite common and they have even lower impedance.

Also there is enough track and wire length to make the point moot as far as the reg goes.

Historically it is actually shunt regs that have issues with capacitance directly at the outputs. But it is very easy to compensate for this, so for most shunt regs it is not a problem.

Linear regs very rarely have any issues with capacitance, as this is what they are designed to drive. :)

As for whoever said that the OSCONs are best used for digital. I will have to humbly disagree. :)

Cheers!
Russ
 
leo said:
TBH I still think this dull sound some people are experiencing is partly down to those SVP polymer caps

Leo, interesting theory, but there is one huge problem. Far more people report exactly the opposite experience. :)

Those SVP caps are actually purpose designed exactly for the application we are using them in.

I presently had some professional folks over who are interested in my design. Lots of comments, but absolutely none of them contained "dull". :)
 
100Hz
 

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protos said:


Why not try bypassing the tube output and trying the voltage output direct from the dac to see where the problem lies.That way you can rule out or not the output stage.

Just to clarify: I'm dealing now with BUF32S as it is, no tubes here. The tubed BUF was the one I heard before, and this one sounded much better in all aspects, even when taking voltage output from the DAC directly, as you suggest.
 
Ringing

Hello Andy:

Thanks for posting the scope pictures. You have far more ringing on that 1kHz square wave than I would expect to see. There was a previous post on either this thread or one of the original Buffalo threads that showed a much cleaner square wave. Search for "Gibbs" because I think the Gibbs phenomenon was discussed.

How are you conducting the test? What is the amplitude of the input signal waveform? What is the scale of the picture? Where are you placing the probe? What load are you driving? More details will be helpful.

What do your supply voltages look like on the scope? You will have to switch to AC coupling to use measure at high sensitivity.

I will try to put the scope on my Buffalo32S later today or tomorrow for comparison.
 
Re: Ringing

wackyterbacky said:
Hello Andy:

Thanks for posting the scope pictures. You have far more ringing on that 1kHz square wave than I would expect to see. There was a previous post on either this thread or one of the original Buffalo threads that showed a much cleaner square wave. Search for "Gibbs" because I think the Gibbs phenomenon was discussed.

How are you conducting the test? What is the amplitude of the input signal waveform? What is the scale of the picture? Where are you placing the probe? What load are you driving? More details will be helpful.

What do your supply voltages look like on the scope? You will have to switch to AC coupling to use measure at high sensitivity.

I will try to put the scope on my Buffalo32S later today or tomorrow for comparison.

The signal amplitude, both sine and squre, is 5Vpp, as the result of "0 dB" level recorded at my test CD. The probe is placed at BUF SE output. The load is passive pre AudioSynthesis, ca 15k input/output impedance, further feeding AN monoblocks.
I'm going to take a closer look at psu voltages as you suggest.
 
Russ White said:


Leo, interesting theory, but there is one huge problem. Far more people report exactly the opposite experience. :)

Those SVP caps are actually purpose designed exactly for the application we are using them in.

I presently had some professional folks over who are interested in my design. Lots of comments, but absolutely none of them contained "dull". :)

Hi Russ,


Well its just advice I was told, we could turn this into a cap debate but its not my intention , all I'm doing is trying to help and not to stand on toes, unfortunately there is a few who are craving more dynamics and life, its basically giving those people some idea's what to try if the sound does not suit them, as I'm sure your aware theres more than this forum discussing your dac and people DO tend to post more PM's than posts on public threads :)

As said earlier I've currently no problem with the sound, I've played about with a lot of stuff and heard a range of dacs , both Buffalo's came out high regarding SQ, beauty with diy is that we can tweak until it suits

Cheers,
Leo
 
Re: Re: Ringing

brgds said:


The signal amplitude, both sine and squre, is 5Vpp, as the result of "0 dB" level recorded at my test CD. The probe is placed at BUF SE output. The load is passive pre AudioSynthesis, ca 15k input/output impedance, further feeding AN monoblocks.
I'm going to take a closer look at psu voltages as you suggest.


Heres what I get 1k 0db, SE output


Buffalo32s

001small.jpg
 
glt said:


In audio, I think burn-in happens inside your ear :).


Ahh - more psychological phenomena misinterpreted as physical phenomena. Pretty much what I thought.

Perhaps the people describing the Buffalo 32s as "dull" are simply registering an absence of the (pleasing?) distortion that they had grown accustomed to from other, less accurate DACs?
Food for thought...
 
Duffy Moon said:



Ahh - more psychological phenomena misinterpreted as physical phenomena. Pretty much what I thought.

Perhaps the people describing the Buffalo 32s as "dull" are simply registering an absence of the (pleasing?) distortion that they had grown accustomed to from other, less accurate DACs?
Food for thought...

The only type of burn-in I've experienced is with people voices: some voices I get to like more (they sound more gentle, soothing, etc) as I get to "know" and hear that voice more. The opposite also happens :). But seriously, if burn-in is a physical phenomenon, then why is it always for the better?. If you look at a piece of silicon integrated circuits, the more you use, the more defects are created into the substrate increasing the level of traps. It is never the case where use will result in a more pure silicon substrate. (Granted those impurities are below the level that they will cause any problems, but stressing it -burn in in an oven- will eventually cause failure)
 
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