[robzy]

Hey guys

Im looking to build a Dynalo and was talking with another that has already built one. He recommended that i socket as much as possible. For a number of reasons, one being so that if i cant stuff up a certain component when soldering it in, and if i do its easily fixable, no hard to do desoldering. (We are talking transistors and things like that).

This sounds all good and fine, but the purists voice in my head keeps on telling me it is a bad idea, that its going to affect sound quality!

Of course, i really dont have much idea about things like this, so tell me - Does socketing components (transistors, etc...) affect sound quality in something like a Dynalo? (or any other amp for that matter?)

Thanks a lot,
Rob.

 

[Voodoochile]

That's a bit of a loaded question. Soldering, if done properly, will make a better long-term connection than your typical socketed connection, IMHO.

There are very nice sockets available or course, and if you install a socket and plug in a chip or transistor, it's probably fine, as far as continuity goes. With a lot of parts-rolling, the contacts will wear though, and also the more sockets in your piece, the more points of failure for a noisy connection due to dust or what have you.

There is also the potential for issues raised by the extra lead length added via sockets. A direct-mounted part has less liklihood of introducing undesireable behavior.

That said, sockets are a great way to confirm a configuration. If you have two boards, solder one up with sockets, and circulate components through it until you find what works ideally for youor application. Then transfer them to the nude board and solder away. I have done this many times, and it works very well, especially with a discrete design.

Many people have their op-amps socketed, which is nice. But (in a PPA example) having all op-amps, buffers, and resistors socketed makes for a huge amount of places for things to go wrong that are largely non-issues with good soldering. The sockets all have the same solder joints for attachment also, so you are doubling the connections for any given component.

 

[nikongod]

there is also the problems of relyability raised.

i hand-built a megasquirt (automotive fuel injection computer, with optional upgrades to control ignition) computer. the build was simple, with well spaced components, and only 2 screw-ups durring assembly. i put the main sower suply diode in backwards, and i did not jumper one position that required jumpering.

afterbuilding this beautyfull box, i sold it. the person i sold it to sold it again. that guy writes to me and asks why its not working, and all sorts of very specfic component value questions. i tell him "open the thing and look" that was the last time i heard from him.

click for pisture of my board
click for picture of front-face of box. note stainless 4-40 screws tapped into case.
y friend who works on these boxes apparently got hold of it to fix, he tests it on his "test-bench" with no results. he cracks open teh box, and the first thing he sees is that the only socketed component *the huge chip in the middle of the board) has wiggled loose on 1 corner. he pushes it down, and it runs like a dream.

immagine if 100 things were socketed. he would have been skrrod to find it.

if you are going to be changing a part or it is possibel that it may break in use, socket it. if not, dont. simple. resistors should rarely be socketed imho. maybee the one necessary to "change" the gain, or the turnon point of the bassboost (if applicable.) i personally think that except for the simplest of portable amps, opamp chips and buffers ALWAYS socketed. this is especically true if your chip lacks output "short to ground" protection.

 

[jamont]

A mechanical connection, such as a socketed component, must be oxygen-free or it will eventually oxidize and fail, even if it does not come loose. This is why most components are usually soldered, the main exception being expensive IC's, like opamps. There is a good discussion of these issues in AoE.

 

[Edwood]

I solder directly everything except OP amps. So I can swap them out later if I want.

If you don't ever plan on swapping them out, measure the voltage supplies for the OP amps before you solder them in place.

-Ed

 

[Emon]

Quote:

Originally Posted by jamont A mechanical connection, such as a socketed component, must be oxygen-free or it will eventually oxidize and fail, even if it does not come loose. This is why most components are usually soldered, the main exception being expensive IC's, like opamps. There is a good discussion of these issues in AoE.

Indeed. Although for the oxidation to start affecting sound quality will take many many years, especially if there's good contact between the legs and the socket - if it's really tight, it's just about oxygen free. I've pulled ICs out of 20+ year old equipment only to see shining copper or tinned legs in contrast with the nasty corroded dull gray that was exposed to air.

Me, personally, I solder everything except ICs on my projects, which are just easier to socket, and safer. I have a lot of experience soldering and desoldering. Things like a good solder sucker, dry wick and especially a pnuematic desoldering gun ($$$) make desoldering easier and safer.

 

[skyskraper]

i can see benefit in socketing the output transistors in the dynalo. especially if it is a first completeley discrete project for someone. if there is a problem during testing then it's easier to track down and fix. i dont believe in the dynalo, that if you have decent sockets and connect them well that there will be a real or tangible negative for using them. better safe then sorry

 

[grasshpr]

If your also worried about oxidation, buy the sockets with gold plating. It will last longer compared with tin based sockets. However, it will cost a pretty penny

 

[robzy]

I fear people miss my point - does it affect sound quality or performance of the amp at all?

Im not really worried about oxidation because by the time that happens i probably will have blown up the amp by dropping a screwdriver in it or something. Although thanks for bringing it up nonetheless, because the issue of oxidation never occured to me.

Rob.

 

[PinkFloyd]

Read this:

 

[Emon]

Quote:

Originally Posted by robzy I fear people miss my point - does it affect sound quality or performance of the amp at all?

No.

 

[mono]

Quote:

I've pulled ICs out of 20+ year old equipment only to see shining copper or tinned legs in contrast with the nasty corroded dull gray that was exposed to air.

It's possible that the contact between the opamp and socket prevented oxidation at that tiny contact point, but it's also possible that the mechanical removal of the part cleaned of the oxidation through the friction.

Opamp connections can become capacitive and resistive in signal path, plus the added impedance and distance from power can matter too. The latter may matter more with faster opamps and those more power hungry. Higher running voltage, in conjunction with opamp current, potentially heats the opamp too which cases slight metal expansion and contraction thermal cycling- opamps can creep out of the socket slightly, just enough that same exact spot of electical contact moves and there is the potential for oxidation or environmental contamination of contacts.

On a new build or soon after rolling amps, the electrical contacts may be better than after a period of time. Even so there could be a gain in audio quality by foregoing the socket entirely and soldering in the opamps- thing is, whether that difference is significant enough to be audible is another matter, it may not be.

Personally, if I already knew for certain what opamp I preferred for a design (and that I wouldn't be selling the amp), I would solder-in the opamps, buffers, etc... after measuring voltages as Edwood mentioned.

 

[PinkFloyd]

Quote:

Originally Posted by Emon No.

so increased interlead capacitance doesn't affect sound quality?

 

[amb]

The major concern of socketing parts is mechanical reliability (if the amp is subjected to vibration and shock then parts may work loose or fall off). This depends on the part and the type of socket used.

For fast circuits there is the issue of trace distance, which the pins of the opamp socket and parts are a part of. However this is rarely an issue if the pcb is laid out well. The small incremental distance of a socket should not cause any difference in performance.

Since the original subject at hand is a dynalo (an all-discrete circuit), the distance added by sockets is miniscule compared to trace lengths that connect from part to part, so that's even less of an issue. If the amp is mostly going to sit on a table then socketing shouldn't be a problem, except for contact integrity over time (corrosion/oxidation). Using good quality sockets should mitigate or eliminate this problem.

 

[PinkFloyd]

Quote:

Originally Posted by amb The major concern of socketing parts is mechanical reliability (if the amp is subjected to vibration and shock then parts may work loose or fall off). This depends on the part and the type of socket used. For fast circuits there is the issue of trace distance, which the pins of the opamp socket and parts are a part of. However this is rarely an issue if the pcb is laid out well. The small incremental distance of a socket should not cause any difference in performance. Since the original subject at hand is a dynalo (an all-discrete circuit), the distance added by sockets is miniscule compared to trace lengths that connect from part to part, so that's even less of an issue. If the amp is mostly going to sit on a table then socketing shouldn't be a problem, except for contact integrity over time (corrosion/oxidation). Using good quality sockets should mitigate or eliminate this problem.

So "Analogue Devices" are talking bollocks when they say:

"IC sockets should be avoided, since their increased interlead capacitance can degrade the bandwidth of the device."

?