Who have experience diy Hi-End amp using SMD component?
Is it difficult to install?
Any information about install SMD component?
Is it better than normal amp using big component?
Is it difficult to install?
Any information about install SMD component?
Is it better than normal amp using big component?
Hello!
It should be better than hole mounted assemblies because of the smaller size (less prone to picking up radiated emissions etc). One issue is of course the resistors where surface mounted 0805s have a bad reputation. When I build SMD assemblies I allways use 1206-MELFs (cylindrical resistors with very low current noise and high pulse power capability) in the signal chain.
It is also important to remember that smaller components have less power capability so adding copper fills around dissipating components is a good advice. When it comes to the emitter resistors in the output stage I build them from four parallelled 1ohm 2010 MELFs with large copper fills around them (Farnellinone order code 308-6483).
It should be better than hole mounted assemblies because of the smaller size (less prone to picking up radiated emissions etc). One issue is of course the resistors where surface mounted 0805s have a bad reputation. When I build SMD assemblies I allways use 1206-MELFs (cylindrical resistors with very low current noise and high pulse power capability) in the signal chain.
It is also important to remember that smaller components have less power capability so adding copper fills around dissipating components is a good advice. When it comes to the emitter resistors in the output stage I build them from four parallelled 1ohm 2010 MELFs with large copper fills around them (Farnellinone order code 308-6483).
It's not much use to change to SMD if not the pcb is made for it. The really benefit SMD you must have a pcb made for SMD.
I like SMD... but never tested MELF resistors yet.
I like SMD... but never tested MELF resistors yet.
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I've constructed a pair of Randy Slone "11.4" amp using a mixture of 0603/1206 SMT and through-hole parts, with larger transistors and large capacitors done through-hole. The amps worked quite well, except I didn't estimate a couple of resistor dissipation numbers correctly and ended up having to bodge larger resistor values onto the board 😉
The pros are short signal paths and a smaller PCB, which makes the amplifier a fair bit smaller and less likely to pick up EMI. And for designs like the 11.4 and 11.6 Slone amps, which are prone to oscillation if you make traces too long, this helps immensely.
You'll definitely need a 2-layer board to construct one though, since you lose the ability to sneak multiple traces underneath resistors. This means etching your own PCBs and making your own vias with bits of wire is painful, and you're best going to a board house. Also, you'll likely run into trouble getting certain SMT NPO capacitor values unless you order a 5000 piece reel...
The pros are short signal paths and a smaller PCB, which makes the amplifier a fair bit smaller and less likely to pick up EMI. And for designs like the 11.4 and 11.6 Slone amps, which are prone to oscillation if you make traces too long, this helps immensely.
You'll definitely need a 2-layer board to construct one though, since you lose the ability to sneak multiple traces underneath resistors. This means etching your own PCBs and making your own vias with bits of wire is painful, and you're best going to a board house. Also, you'll likely run into trouble getting certain SMT NPO capacitor values unless you order a 5000 piece reel...
bmpa said:
Most consumer electronics uses SMD components. These boards are assembled by pick and place machines which get the components from reels or tubes, place them, glue them in place; then the board is reflowed using infrared. You can't duplicate this process inexpensively. However, you can use the components with certain special SMD rework tools for soldering.
If you take advantage of the small size, you will have a more compact design which may eliminate some strays and noise with proper layout. An example of a partially surface mounted amp for home assembly is Anthony Holton's as yet unreleased new N-channel amp, pictured here:
http://www.aussieamplifiers.com/New N-channel.htm
This is not a particularly compact layout, it could be half this size. Only the driver transistors are surface mounted. Note that the power devices and filter caps are huge relative to everything else, so there is a limit to how small you can make it.
bmpa said:
HI!
Densen - among others- is using SMD in their amplifiers. I belive this is one of the reasons for the good quality of the sound.
Beside that - if You find metal film resistors in SMD- You will only find them from few companies (with names and nothing like no name stuff). I have used SMD in my d/a converter and one can solder them - it is not a problem- You have to have temperature controled soldering iron and use 200-220 Celsius. Also You have to be quik with soldering and it would be good to have the third hand to put the smd's to the place while You are soldering. My girlfriend is used to help me with that. I have used pin sharp needle to hold the smd's to the place.
Hope this would help
regards
daniel
😀 😀
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