resistors revisited
Ok, Vishay-Draloric is kind enough to provide non-linearity and current noise specs for their resistors.
The SMM0204 - MS1 parts are Mini-Melf (i.e. cylindrical SMD) metal film parts with a rating of 0.25 W. Non-linearity A3 for a 10 k part is 110 dB. I do not remember the exact definition, but I believe it is resistance change per volt and hence should read -110 dB. Current noise for 10 k is 0.05 µV/V.
The D...-CRCW series (available down to 0.5% tolerance) are rectangular metal glaze SMD parts. A 10 k 1206 (also rated at 0.25W) has a nonlinearity of 65 dB, a 0402 will only have 50 dB. Current noise is 0.1 µV/V for the 1206 package and 0.5 µV/V for the 0402.
So we can safely conclude that metal glaze, whatever its composition, is sonically inferior and should be avoided as feedback and filter resistors.
Eric
Ok, Vishay-Draloric is kind enough to provide non-linearity and current noise specs for their resistors.
The SMM0204 - MS1 parts are Mini-Melf (i.e. cylindrical SMD) metal film parts with a rating of 0.25 W. Non-linearity A3 for a 10 k part is 110 dB. I do not remember the exact definition, but I believe it is resistance change per volt and hence should read -110 dB. Current noise for 10 k is 0.05 µV/V.
The D...-CRCW series (available down to 0.5% tolerance) are rectangular metal glaze SMD parts. A 10 k 1206 (also rated at 0.25W) has a nonlinearity of 65 dB, a 0402 will only have 50 dB. Current noise is 0.1 µV/V for the 1206 package and 0.5 µV/V for the 0402.
So we can safely conclude that metal glaze, whatever its composition, is sonically inferior and should be avoided as feedback and filter resistors.
Eric
Re: resistors revisited
How anyone conclude anything from this data? You have not compared the numbers to the same specs of any leaded parts. You also have not provided figures for audibility of any of those numbers, which I suspect would vary significantly depending upon the application.
This is exactly the sort of jumping to conclusions that makes reasonable people laugh at audio maniacs. Decisions/beliefs are presented as if they are based on science/engineering, but with very little scratching at the surface it becomes apparent how shallow the reasoning really is.
MR
capslock said:
How anyone conclude anything from this data? You have not compared the numbers to the same specs of any leaded parts. You also have not provided figures for audibility of any of those numbers, which I suspect would vary significantly depending upon the application.
This is exactly the sort of jumping to conclusions that makes reasonable people laugh at audio maniacs. Decisions/beliefs are presented as if they are based on science/engineering, but with very little scratching at the surface it becomes apparent how shallow the reasoning really is.
MR
Panasonic smd film caps
Hi there!
Panasonic also makes PPS smd caps, and digikey sells them.
And something quite interesting is "acrylic resin" film smd cap (ECPU series) made by the same company. (Digikey has them too.) They say something like "it sounds very good."
Check out the URL:
http://www.maco.panasonic.co.jp/eccd/index.html
tiroth said:
Hi there!
Panasonic also makes PPS smd caps, and digikey sells them.
And something quite interesting is "acrylic resin" film smd cap (ECPU series) made by the same company. (Digikey has them too.) They say something like "it sounds very good."
Check out the URL:
http://www.maco.panasonic.co.jp/eccd/index.html
based on science/engineering
Tempo and Voltage Coefficient seem to be two of the most often quoted specs for high precision resistors. Since the power dissapated in a resistor will very with signal swing, a dynamically changing temperatures are varying the value of the resistance with signal ie. a nonlinearity. A simular argument can be made for
chance in resistance with voltage due to Voltage Coefficient. Data for two of the more highly regarded resistors for audio are at:
http://www.caddock.com/Online_catalog/Mrktg_Lit/TypeTF.pdf
http://www.vishay.com/document/63001/63001.pdf
Further complicating this are thermal conductivity and thermal mass of the resistive film, substate, and encapsalating material.
Several zealots are using "naked" Vishays without the encapsulation. Perhaps the thermal characteristics are better without the thermal insulation. There has also been trend in using oversized resistors by some manfactures. Differences in thermal mass perhaps? I believe there are many engineering parameters that could cause resistors to sound different. The datasheets above will give a bench mark for good numbers for Tempco and Voltage Coefficients for the spec readers.
H.H.
Also for more background:
http://www.riedon.com/handbook_default.htm
http://www.riedon.com/app_notes.htm
http://www.metechinc.com/solutions/voltage.html
Tempo and Voltage Coefficient seem to be two of the most often quoted specs for high precision resistors. Since the power dissapated in a resistor will very with signal swing, a dynamically changing temperatures are varying the value of the resistance with signal ie. a nonlinearity. A simular argument can be made for
chance in resistance with voltage due to Voltage Coefficient. Data for two of the more highly regarded resistors for audio are at:
http://www.caddock.com/Online_catalog/Mrktg_Lit/TypeTF.pdf
http://www.vishay.com/document/63001/63001.pdf
Further complicating this are thermal conductivity and thermal mass of the resistive film, substate, and encapsalating material.
Several zealots are using "naked" Vishays without the encapsulation. Perhaps the thermal characteristics are better without the thermal insulation. There has also been trend in using oversized resistors by some manfactures. Differences in thermal mass perhaps? I believe there are many engineering parameters that could cause resistors to sound different. The datasheets above will give a bench mark for good numbers for Tempco and Voltage Coefficients for the spec readers.
H.H.
Also for more background:
http://www.riedon.com/handbook_default.htm
http://www.riedon.com/app_notes.htm
http://www.metechinc.com/solutions/voltage.html
For my prototyping, and I do a lot of it, I stay away from thru-hole parts. SMD have very low inductance, to allow high bandwidth amps etc...Sure, they're small and difficilt to handle for many. Here's a definite solution to their handling:
http://www.t-rexelectronics.com/
http://www.t-rexelectronics.com/
Those amps are nice examples of SMT parts.
http://groundsound.com/images/pa3cc_l.jpg
http://groundsound.com
http://mirand.dk/smallheats3.jpg
http://mirand.dk
http://groundsound.com/images/pa3cc_l.jpg
http://groundsound.com
http://mirand.dk/smallheats3.jpg
http://mirand.dk
Metal film surface mount resistors are certainly fine for all audio applications. Thick film SM resistors are ok too for less critical use and are much cheaper than metal films. If you want precise gain matching go for the 1% or tighter tolerance metal films.
As has been mentioned here and there on this forum, ceramic SM caps with NP0 or C0G dielectric are fine for all audio applications. X7R and other dielectrics aren't as good as NP0/C0G, but work fine for decoupling.
As has been mentioned here and there on this forum, ceramic SM caps with NP0 or C0G dielectric are fine for all audio applications. X7R and other dielectrics aren't as good as NP0/C0G, but work fine for decoupling.
I love SMT for prototyping because I can avoid all that tedious drilling ...
I have no trouble hand assembling SMT (0603, 0402, QFP etc), even with a fat, butcherous iron. Its all in the technique.
And if you want to parallel resistors, SMTs just stack on top of each other!
All those complaints about Tc etc apply equally to leaded parts - its not specific to SMT .
I have no trouble hand assembling SMT (0603, 0402, QFP etc), even with a fat, butcherous iron. Its all in the technique.
And if you want to parallel resistors, SMTs just stack on top of each other!
All those complaints about Tc etc apply equally to leaded parts - its not specific to SMT .
peranders said:
I agree with peranders. You have to really bend a board to get parts or solder joints to break, although orientation and location on the PCB have a big influence on this. Most boards are fairly stiff, especially if the dimensions are under about 4-5 inches a side and the PCB is the standard 0.062in FR4, double sided, 1oz copper. For 0805/0603 types the part itself usually breaks before the solder joints if the pads are the correct size and the soldering is done properly. Ceramic caps are more prone to breaking/cracking than resistors.
Is there a better way to solder SMD other than soldering on end and then soldering the other end? Does it pay to dispense solder paste then glue the SMDs on to the PCB, then pass it thru a "reflow" owen.
I use home owen to smooth out the solder joints but I wonder about the use of solder paste. Any wisdom out there?
I use home owen to smooth out the solder joints but I wonder about the use of solder paste. Any wisdom out there?
koolkid731 said:
Its not really worth it imo unless you use small pitch or no lead parts, then it should be much easier w/ reflow. But if you are already throwing the board in the oven, it would save time.
Tube of solder paste from digikey is ~$50 if you want to try it out. No need to glue the parts down if you are careful.
koolkid731 said:
Paste and a reflow oven is best, but you'd be lucky to have access to a real one let alone have one
The next best method is to use paste and a hot air rework station. The next best method is a good old adjustable temperature soldering iron with a chisel tip. Use liquid flux when possible for any method to get good solder joints with surface mount parts and clean with isopropyl alcohol and lint free wipes/cloth to remove any flux residue.koolkid731 said:
thomas997 said:
Usually glue is used for wave soldering. When heated properly most parts will center themselves when passing through a reflow oven thus no need for glue to hold the parts down.
Thx for the replies.
I haven't tried solder paste because of the need to dispense it onto the pads, in small droplets (????) then to place the SMDs, all of them. What if I hit the boards and dislocated some SMDs? I would have to reposition them again, wouldn't I. Plus solder paste seems expensive. I bought some but never got around to use it and it's expired by now, most likely (I haven't dared opening the vial!)
I looked at some sites on SMD soldering. They seem to use just solder wire, like what I still do.
Why should one remove flux with isopropanol? for reliability? to prevent further chemical reaction? (acid attack?)
I haven't tried solder paste because of the need to dispense it onto the pads, in small droplets (????) then to place the SMDs, all of them. What if I hit the boards and dislocated some SMDs? I would have to reposition them again, wouldn't I. Plus solder paste seems expensive. I bought some but never got around to use it and it's expired by now, most likely (I haven't dared opening the vial!)
I looked at some sites on SMD soldering. They seem to use just solder wire, like what I still do.
Why should one remove flux with isopropanol? for reliability? to prevent further chemical reaction? (acid attack?)
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