[_Spanky_]

Quick question for those that know more about electronics and ohms and whatnot than I do... Would it be "bad" if I used say, 4 opamp sockets between a PCB and the opamp itself? I could cut it down to 3 (which is what Kingwa uses on HDAM's if you include the extension leads) but I would prefer 4.

I'm not going to say what this is for just yet as I'm in the fact checking stages but basically it would go something like this:
Opamp socket soldered to PCB > opamp socket > CAT5 (solid wire) extension leads > opamp socket > opamp socket > opamp

Also, I looked around and it looks like the following are what I want:
8 PIN SOLDER TAIL DIP SOCKET - 08-3518-10
Is that right?

 

[FallenAngel]

Really depends on the opamp; if it's a high speed opamp that requires psu bypassing close to the power pins to stay stable and these caps are too far from the chip, the opamp may become unstable.

 

[Juaquin]

If you're using that much space between the opamp and it's feedback network it might be a problem (small resistances, capacitance, inductances), especially using Cat5 which isn't exactly the best sounding stuff (if we're talking about audio). It's something I'd personally try not to do if there was any other way - I mean, it might work (I'm not an expert on this by any means) but why risk it if you can get around it. Also, the stability issues as mentioned.

 

[_Spanky_]

I would be using the Audio-GD HDAM's. Basically they won't fit where I want them to so I would route them to another box. For the length, I'm only thinking a maximum of 6 inches. I have vast amounts of CAT5 and the number of pairs/strands works out pretty good. I MIGHT have some Mogami Neglex that I could use but would I notice the difference?

 

[amb]

Not just supply bypassing, but some opamps are very finicky about having a very short feedback loop. Any added inductance in that path (which would be introduced by stacking sockets) could make the circuit unstable. Certain opamps can't tolerate even one socket, and must be soldered directly to the board. Fortunately these are usually SMD devices that can't be socketed anyway.

 

[_Spanky_]

Well, I've re-thought what I wanted to do and will be using 3 opamp sockets now between the PCB and the HDAM. This would be the same setup as the Zero & HDAM users had.

My only thing now, would CAT5 be such a bad idea? Like I said, I could use Mogami Neglex but I would rather use it for something else. I'm now looking at a maximum of 10 inches.

Thoughts?

 

[Juaquin]

I'm not a big believer in cables making a huge sonic difference, but I've played with Cat5 for interconnects and I'm not a fan at all. It's stiff, brittle, and the quality of the wire inside just didn't leave me impressed. I would go for the Mogami, even if you remove the outer casing/shield and just use the internal wires.

 

[_Spanky_]

Alright, I may just have some spare Mogami after the cables I make soon. I would strip out the individual wires of it to make it a diameter that would fit in my application. Thanks for the advice, better to do it right the first time

 

[FallenAngel]

These Audio-GD "HDAM" things aren't really opamps and they look to have bypassing caps on the boards themselves. 10 inches is WAY longer than I would ever want a feedback loop, and as it's effectively 20 inches since there is the input/output wires, it's scary. Anyways - try and see for yourself. Just make sure to measure offset and test for heat (or better yet, with a scope for ringing) before plugging anything into it.

 

[_Spanky_]

Hmmm, I don't want any major problems and I don't have scope to test it only a DMM. I might be able to fit the HDAM's in the socket but I would have to cut the case for the height. Also I might have to use a socket in the socket soldered to the PCB to give me enough height around the surrounding components. Would that be any better or "right" to go PCB > socket > socket > HDAM?

BTW, thanks for informing instead of flaming FallenAngel. I'm not suggesting anyone has on these forums but it's nice to see people that inform without flaming and I try to thank those people

 

[ROBSCIX]

The audio-GD units aren't really high speed, so I would doubt you would have any trouble with them becoming unstable. Though, you never know.

What about the extension wires they make for those opamps, Would those work for your project? As you noticed some will frown on such things (I am not to cool with them either) but they are needed to use these modules in most circuits because of their size.

 

[_Spanky_]

Yea, Kingwa said that 6 inches wouldn't be a problem but I didn't ask him about how many sockets and whatnot. I couldn't use his leads because I need to run the wire through a hole that would be too small for the opamp socket so I would have to cut the ones he made and re-solder them. By that time, I may as well make my own the right length. However, I'm thinking of abandoning this route and instead cut holes in the box to allow the HDAM's to poke through. Now the only problem is the area around the socket on the PCB...

 

[Juaquin]

Let us know how it turns out, I'm interested in seeing some HDAMs sticking out of a case. You could try your cable solution and hook it up to a dirt-cheap pair of earbuds to listen for ringing if you don't have a scope (obviously, don't put them directly in your ears until you're sure it sounds ok).

 

[_Spanky_]

Quote:

Originally Posted by Juaquin /img/forum/go_quote.gif hook it up to a dirt-cheap pair of earbuds to listen for ringing if you don't have a scope.

Ah, those I do have

I will have to get a few bucks together to buy the HDAM's and a few parts from digikey but right now it seems I have too many things to spend my money on... I do plan to start a thread and I will link to in this one. Thanks for the help everyone