TH vs SMT for audio
T Chap
Posts: 4,223
I’m thinking about cloning an old mic pre that is “Class A discrete”. All transistor, all through hole components hand mounted, transformer in and out. bar graph LED display. With most of these high end boutique hand made pre’s they always boast hand made, point to point wiring as part of the “magic”. In this case it hands down one of the best mic pre’s comparing to classic Neve etc.
One of the problems for these small company is they would not try to cut costs on the single rack space quad channel or dual channel product. I’m wanting to find out I can concert much of the resistors, diodes, transistors, small non signal caps, non signal inductors to SMT that I can pick and place to make a board take just a minute to populate vs a ton of hand wiring. Then use TH for the large expensive signal caps so they can be replaced as needed or swapped for sound. Can the sound be just as good with 0603 resistors? I notice they claim they were “hand matching” transistors and sorting them into matched sets for assembly. Not sure what that really accomplishes or if it’s worth it, but SMT transistors would be not as easy to do that to.
One of the problems for these small company is they would not try to cut costs on the single rack space quad channel or dual channel product. I’m wanting to find out I can concert much of the resistors, diodes, transistors, small non signal caps, non signal inductors to SMT that I can pick and place to make a board take just a minute to populate vs a ton of hand wiring. Then use TH for the large expensive signal caps so they can be replaced as needed or swapped for sound. Can the sound be just as good with 0603 resistors? I notice they claim they were “hand matching” transistors and sorting them into matched sets for assembly. Not sure what that really accomplishes or if it’s worth it, but SMT transistors would be not as easy to do that to.
Comments
All good questions. Welcome to the realm of "audio voodoo". Not saying there would be no-difference between hand-wired, through-hole and auto-assembled, printed circuit cards. I'm saying that it can be a situation of diminishing return based on what you hear and how you perceive what you're hearing. Oh, and the target market.
If your target market expects hand-wired, discrete through-hole components, then convincing them that an SMD, PC assembled unit would sound the same (or as good) would be a hard sell. If your target market only listens to music through ear-buds, then the likely hood of hearing subtle nuances in circuit design will be small.
The "sound of components" has been embroiled in controversy for decades; welcome to the party (smiles).
Build what you want, the way you want. Use good quality components and stable circuit designs. Someone will buy it and will be happy with their choice.
Merry Christmas!
Dave
Amplifier is only one piece of the puzzle. Don't forget the $10,000/each cables
And the $20,000 record player
Oh and forget about the crappy wiring behind the wall....you still need a $2,000 AC power cord.
In many audio circuits, to minimise distortion, you need matched pairs of transistors with near-identical gains. A typical small-signal transistor is specified with a wide gain range; it's not unusual to see 3:1, or even 5:1, variations in small-signal gain.
ha ha yes! fix the network copper with a meter of kryptonite!
I wonder if adding trim pots to the specific transistors that need to be matched and hooking up test points could be more rapidly done it more cost-effective than taking a transistor out of the circuit by hand trying to match. I’m meeting with a guy that designed the original circuit next week then so I’ll get an explanation of what is involved in the hand matching and how that could be streamlined
https://www.analog.com/en/parametricsearch/10988
https://www.mouser.com/Search/Refine?Keyword=matched pair transistor&gclid=Cj0KCQiA0ZHwBRCRARIsAK0Tr-qcM_u342hu5rNbLR6lkwfwQsEX47XbiADQRmLR4SB7WEswuQPNMO8aAtSGEALw_wcB
https://www.diodes.com/products/discrete/bipolar-transistors/matched-pairs/
or do these not fit into the audio category?
Thanks for that suggestion I’m gonna bring it up and see if that helps reduce some labor