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Old 23rd August 2013, 12:29 PM   #31
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It's very easy to transform this simple project into diyer's nightmare by two simple steps:

1. use hard to obtain expensive parts from many different sources
2. use miniature SMD parts that many diyers find difficult to solder

We do not want to compete with Nagra Kudelski in miniaturization game, don't we?
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Old 23rd August 2013, 01:56 PM   #32
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We are having first batch of 250 PCBs produced for our DIY Subbu V3 DAC that is mostly SMD and even some very small parts. Not an easy PCB to solder for inexperienced builders. In fact I discourage new DIYers to join such a project. Yet there are quite a lot of DIYers that do this DAC as a first SMD project... (not my choice). I have seen examples of great workmanship by inexperienced "SMD DIYers" with the previous version. "Hard to get" parts come from various sources as well. PCB is smaller than a packet of cigarettes while having 4 power supplies with decoupling etc.

Please see PCB in the first drawing:

"Subbu DAC V3 - ES9023/WM8804 SPDIF & Power Supply PCB" Group Buy

I think the "DIYers nightmare" is not everybody's nightmare...if one wants to achieve something then just do it. There is more than enough mediocre stuff around so building something very good for a reasonable amount of money is one of my goals in audio. Building standard or below standard stuff automatically makes the design redundant from the start.

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Last edited by jean-paul; 23rd August 2013 at 02:18 PM.
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Old 23rd August 2013, 03:10 PM   #33
Bonsai is offline Bonsai  Taiwan
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So no SMD - ok clear.

JP, the PSRR of the middle circuit I poster up worst case ( so at LF) is - 90 dB and it gets better as frequency goes up. Now, this is using perfect components, so esr is not modeled for example, but this is way better than an IC reg.

I am in the middle of testing a big new preamp I am building, and spent a lot of effort on the PSU. The humble RC filter, CCS and cascoding can work wonders.

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Old 23rd August 2013, 04:27 PM   #34
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I've seen preamp section psu in Yamaha integrated AX492 consisting of simplest shunt reg (resisitor+zener) and RC filters close to opamps. Measured and subjective level of noise is very low! (Almost all preamps using series three terminal regulators have more psu generated noise.) For the simple circuit like this buffer nothing else is necessary. Only for the circuits that consume much more current we could think of three terminal IC regulators.

In industrial applications for portable electronics SMD is great but all the best sounding gear that I heard use only TH parts. I am surprised that builders are willing to accept such drag in diy audio electronics.

Last edited by ivanlukic; 23rd August 2013 at 04:37 PM.
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Old 23rd August 2013, 07:26 PM   #35
qusp is offline qusp  Australia
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the lowest noise, highest performance parts of just about any type currently available are SMD parts, the layout benefits are many, shortest signal path, lowest parasitics, most compact and built from reasonably priced commonly available parts available at the major vendors.

soon enough you wont be able to build anything if you keep resisting SMD. most of the highest dollar gear in high end audio, instrumentation, video, computing, avionics, space flight, deep space exploration, medical imaging, the highest performance, lowest noise, fastest 'camera' ever built, with unlimited budget, the LHC sensor arrays that recorded the 'God Particle'.. SMD

nothing to do with portable, though it has advantages there too. its not to save money, not to cut corners, not just to save space, not just to automate assembly, but for higher performance

simple low noise circuits need better power supply in general, i'm not following your logic there.

SMD is really not that hard, but it requires a couple new tools perhaps and some practice for new technique, do not think you have to solder each little pin individually, flux is your friend. I find it much less of a pita than PTH. fine if you dont want to do build with it, but soon enough you will only be able to use NOS, thats the reality of the situation. many of the higher performance discrete parts, even the same dies as were in to92 or similar, are now packaged in SMD only, with the PTH going, or already gone EOL.

it will be better if you just pick a simple, fairly cheap circuit thats easy to troubleshoot, like this one for example … and build it in SMD, stop making excuses caused by reasons other than audio quality. you do want to keep building stuff yes? honestly I cant think of a better starter SMD project to pop your cherry with

like JP, i'm not going to push, I wont hang around, but I post these reminders here on DIYA now and again, as the situation is becoming more and more real

Last edited by qusp; 23rd August 2013 at 07:37 PM.
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Old 23rd August 2013, 07:53 PM   #36
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qusp,
Having never done any smd work how is it that you solder multiple leads without having to heat each junction with an iron? Obviously in mass production they use other methods but how does it work in diy? Does that mean that the boards are already coated with solder and you are only re-flowing the solder? Even then how do you heat multiple connections simultaneously?
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Old 23rd August 2013, 08:39 PM   #37
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flux the pads, use a 3-4mm chisel tip, or hoof or well tip; lightly tin the tip; swipe each side, clean up excess or bridges with braid and flux if necessary. with these little sot232 etc parts its dead easy. same with the sot236 or soic8. if your PCB has a decent soldermask and already has a solder layer applied even better, surface tension does most of the work for you.

then you have drag soldering, which takes it another step further with the same idea

HowTo: Drag Soldering Demo - YouTube

I think its this idea that you need to be soldering every single little pin with a fine tip, which is not only the wrolng way to do it, but is also a big part of the fear people have. its the surface tension and flux, with hand soldering and reflow soldering or hot air soldering, that does all the work. dont use too much downward pressure with this technique, just glide along the pins, dont be shy with the solder and flux, you can always clean it up; dont linger, keep moving.

a larger tip is generally preferred to overcome the thermal mass of ground planes etc, using a too small/fine tip makes it much more difficult IMO, the PCB and parts can easily wick all the heat out of the tip and it wont solder/flow properly

Last edited by qusp; 23rd August 2013 at 08:58 PM.
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Old 23rd August 2013, 08:59 PM   #38
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Thanks Jeremy,
That U-Tube video sure makes it look easy. So with the quick movement of the iron you don't have any problems of bridging the solder between pins it appears.

Steven
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Old 23rd August 2013, 09:54 PM   #39
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F..ck SMD!
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Old 23rd August 2013, 10:08 PM   #40
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Wow, no SMT,sorry but definitely a bunch of amateur's here!! It' is like a kid who won't eat but has never even tasted.
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