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[zenharmonix]

Dear Klaus,

I have read some of your replies and comments on using SMT [SMT = Surface Mount Technology, whereby miniaturized components like transistors, resistors capacitors, microchips, etc. are placed on circuitboards through robotics and other automated processes, KH] in mic design. If I understood correctly, you stated that achieving phase integration and low artifact signal is harder with SMT. Sorry if I did not get it right.

I am using analog hardware in my studio, mostly 'older' designed gear with no SMT components (mastering EQs, compressors, some tube gears), and I found their sound very pleasing and satisfying. I also have some gear with SMT (preamps, EQs), and - I know it is not a proper A/B comparison - I feel they sound different. For example, if I try to use a little more extreme settings (pushing them more, applying heavier compression, adding more gain to an EQ band) they start to sound more 'desintegrated'. It does not mean they sound bad at their sweet spot. I have an impression I have to set them more carefully.

I am not searching an answer for a non-existing problem, and I certainly do not have enough knowledge in electronics. In many forums, people say that SMD components are the same if not better than TH parts [TH = Through Hole, whereby individual components of traditional sizing are soldered in place, KH]. Others says that the design is different, so the two technology cannot be compared at all.

Again, my intention is not to get a one-dimensional truth (SMT is bad, TH is good), I just like to see clearly. Most of the manufacturers went towards the SMT road but some of them seems to resist. Would be good to have any insight if the difference I can hear is based on the technology change or something else.

Thank you very much. And sorry if it is a kind of silly question.
Peter

[Kai]

SMD / SMT parts are not in general different to or worse than Through-Hole parts.

Active chips like OP-amps and transistors can benefit from the SMD’s housing’s shorter signal path and less stray capacitance and inductance.
The internal chips are the same anyway.

Resistors are so-so, largely depending on their purpose and values, but no general problem.
Just a question of correct dimensioning.

The main problem are electrolytic caps:
All caps sound different anyway, specially electrolytic caps have highest non-linear distortions of all types.
This is objectively measurable, and I have a test fixture for these measurements.

The tiny SMD electrolytic caps are, on average, worst of all, plus:
They deteriorate much faster than bigger ones, making the situation even more worse.
Good circuit designs avoid them completely.

RME’s ADI-2 series is a perfect example how to do it:
All SMD, but no SMD electrolytic caps, and no electrolytic caps in the signal path at all, with the exemption of one non-avoidable position where selected, big audio-El-caps are used.

[klaus]

Two additional issues worth considering when choosing mics using an SMT layout and/or chipped components:

1. Cross talk, parasitic capacitance, reactance and especially inductance are unintended changes in the behavior of circuits, due to extreme proximity of components or traces; parts are so closely spaced, their electric properties influence and "rub off" on each other. 

As an example, here is a simple explanation of the parasitic inductor effect, where a change in the current flowing through the conductor creates (induces) a voltage in that conductor, as well as all nearby conductors:
https://eepower.com/capacitor-guide/fundamentals/parasitic-inductance


2. With micro-sized or fully embedded components, servicing, improving or repairing at the component-level is made difficult or impossible.
For example, no schematic is made available for the ICs (Integrated Circuits) used in Neumann's TLM mics, and no work-around is possible to repair or improve such components or circuits.
 

[soapfoot]

It's important, I feel, to remember that correlation doesn't always equal causation.

"Mic preamp A has SMT components and sounds bad, mic preamp B has through-hole components and sounds good" is very poor evidence against SMT components.

A current-production piece of gear that uses exclusively through-hole parts in 2023 will not have been made with manufacturing expediency or cost-consciousness in mind, and this will almost certainly inform other aspects of the design.

But that doesn't mean that a device designed with SMT parts was made to be cheap--the designer may have gone that route due to:

• a use case in which the smaller parts were advantageous due to reduced intra-component capacitance and inductance
• choosing a more-optimized part where a through-hole equivalent has gone EOL (i.e. "discontinued by manufacturers, or soon will be")
  
• the ability to achieve a high level of functionality in a physically-smaller form factor than would be possible using through-hole technologies
• other non-cost-related factors