What is pressed vs machined opamp sockets?

[axero]

I was reading this article:

http://www.guru3d.com/articles_pages/sound_blaster_x_fi_titanium_hd_review,12.html

and it said:

"... the company used pressed opamp sockets; they should have used machined units.  Machines units last longer and are higher quality for the end user when swapping out opamps..."

What is 'pressed opam sockets', what is 'machined opamp sockets', and what is the difference between them? Google fails to help me with that.

[c4757p]

They're just IC sockets, nothing special for op amps.

Pressed:


Machined:


The machined ones indeed often last longer, as the spring-like contacts of the pressed sockets eventually wear out.

[amyk]

In my experience the machined ones also require a lot more force to extract ICs from them... anyone remember these?

[yashrk]

True they require the same amount of force

[axero]

The price difference cannot be significant so I cannot see why an OEM would go for pressed sockets if they don't last as long as the machined sockets, unless they want the device to break sooner. But then again, would it matter so much on a device where you don't swap IC's frequently anyway?

I read however, posts on forums from people complaining that Creative cards develop a scratchy and noisy sound after a few years of use.

Thanks a lot for your answers!

[Monkeh]

The price difference cannot be significant

Oh, yes, it can.

http://www.digikey.com/product-detail/en/ED08DT/ED3044-5-ND/4147594
http://www.digikey.com/product-detail/en/SA083000/ED3038-ND/3313520

[electronics man]

I hate whith a passion the machined type as I often find that the legs of the is get damaged more easily, I can understand why they are used in a product but not in hobby stuff, but pressed are much better for prototype units.

[uwezi]

anyone remember these?

Yes I do - its companion the '387 had to go in a similar socket next to it 

About the sockets in general: I always wondered if there was a long-term difference between those sockets. Of course they behave (and last) differently when the chip is frequently taken out and replaced, but in steady operation...?

[cybermaus]

I agree with electronics man above.

For pressed (flat) DIP chips, pressed sockets may actually be better. Even if you replace the chip dozens of time, the machined socket may last, but the chance of having one hole filled because a flat leg got caught and broke of is not imagined.

And the 386/387 example above: those chips have nice round machined pins. So I think this rule makes sense:

Machined (round) pins go into machined (round) sockets.
Pressed (flat) pins go into pressed (flat) sockets.

[pickle9000]

I have noticed over the years when it comes to chip creep. Pressed (flat) sockets do a better job, at least with 8/6 pin dips. Not uncommon to find chip creep with any socket but often with machine contact (round) the chip can fully eject from the socket (and be found loose in the product).

I do like machine contacts so try to ensure that it can be caged / held in place.   

[SeanB]

Standard for socketed IC's in military and aviation is to have a hole each end of the package so you can either use a tie wrap or some lacing twine to hold the chip in the socket so it does not vibrate out. With both you have a drop of locking varnish to hold the knot or the tie rachet so it does not loosen as well. been a while since I did loom knitting, must see how bad I have become. Tie wraps and spiral binding make it all too easy. Still have 2 rolls of waxed lacing twine, and 1 of unwaxed.

[linux-works]

I prefer machines, generally, but in one case, the pressed socket is better: really big chips.  when I do proto builds of arduinos, I prefer the pressed sockets.  they just insert and remove a lot easier when its a skinnydip-280 form factor.

for 16 and 14 and 8pin chips, machined is the only way to go.

[sleemanj]

I can understand why they are used in a product but not in hobby stuff

With some machine pin socket strips in your drawer you can make a socket for any through hole IC length/width you want.

[linux-works]

at least we've gotton away from those horrid 'molex pins'!

I bought a bunch of those in the 70's, thinking they were so cool.

now that I look inside heathkits (recently bought a nixie counter by heath) I see how badly those do, over time.  lots of metal there, too, which isn't so good for capacitance on nearby pins.

[axero]

I think I understand the reviewer's concern about the pressed IC sockets now. The thing is that it is not too uncommon among audio enthusiasts to swap out the OP-amps and try other varieties in the hardware. There are companies that specialize in designing and selling such circuits for such enthusiasts to try and experiment with...

[deth502]

i detest machined sockets. i like the idea of them, and they sure do look a lot prettier, but trying to get anything in/out of them is mostly a lesson in straightening bent ic pins.

[linux-works]

which is why for 28 pin chips, I tend to avoid the machined pin style.

I have had arduino chips go bad on me before and pulling them out of MP sockets is no fun at all.