[NCSUZoSo]

Hey guys/gals, it has been a good while since I posted, been so busy with school. However I am testing out some op-amps for Burson audio and instead of setting up a complete A/B switch with two identical rigs, is it possible to pull and insert op-amps while the card is inserted and the power is on?
 
I know on a breadboard this is safe, but I don't know the ZXR circuit well enough to say that this is safe. Of course the orientation will be correct!
 
Has anyone tried this?  I guess I could use a few of my cheaper op-amps to test the theory first, but is there any risk of damaging the card? Surely there is built in safe guards to prevent anything from going awry too badly.
 
Pic of rig:
 

 

[tomb]

No offense, but your subject line is a recipe for disaster.  If you think it's safe on a breadboard, it's only because you've been lucky.  Dropping a paper clip in there while things are running may get you the same results.

 
You should be able to do this without an A/B switch, too.  Get familiar with a piece of music - listen to the specific dynamics and response of certain passages, then use that to compare.  A giant cymbal crash, a singer's voice with clear breathing, a significant drum hit, or string plucks - many of these can become invisible on lesser equipment.  Or, details are not the same and become smeared or subdued.
 
It's not that difficult to tell the differences with the right passages if you have good familiarity and are listening for the right things.

 

[NCSUZoSo]

Sound like you under the impression hot swapping op-amps in any scenario is dangerous, which isn't true. Op-amps can be used to accomplish a variety of tasks in circuits, so it really depends on what you are building. I haven't built a DAC or headphone amp yet (no time..), so I can't say what what would happen with how they are used in this sound card. Many people assume pulling a transistor with power on is dangerous to the transistor, it's really (possibly) dangerous to the rest of the circuit, not the transistor being pulled.

I do agree with you that it is possible to do it without doing A/B testing, but every reputable review site is using some form of A/B testing (usually double blind A/B). I am looking to start up a review and electrical modding/building site (already have the domain), so I'd like to have semi-professional testing techniques. I do have an oscilloscope which would allow me to actually view/capture the raw output signals for comparison.

I just finished speaking with Creative Inc. and their Engineering Department is going to email their recommendation on this topic. That tells me there is no red flag popping up to the normal Creative support guys on the topic. My plan is to build two switches with each one connecting two DIP-8 sockets together, this way you could literally pop back and forth between the op-amps (not quite as simple as it sounds, but that is the general idea).  The problem is, electrically this is the exact same as pulling/inserting them with the power on as described in the OP (which is why I asked the way I did).

 

[tomb]

  Sound like you under the impression hot swapping op-amps in any scenario is dangerous, which isn't true. Op-amps can be used to accomplish a variety of tasks in circuits, so it really depends on what you are building. I haven't built a DAC or headphone amp yet (no time..), so I can't say what what would happen with how they are used in this sound card. Many people assume pulling a transistor with power on is dangerous to the transistor, it's really (possibly) dangerous to the rest of the circuit, not the transistor being pulled.

I do agree with you that it is possible to do it without doing A/B testing, but every reputable review site is using some form of A/B testing (usually double blind A/B). I am looking to start up a review and electrical modding/building site (already have the domain), so I'd like to have semi-professional testing techniques. I do have an oscilloscope which would allow me to actually view/capture the raw output signals for comparison.

I just finished speaking with Creative Inc. and their Engineering Department is going to email their recommendation on this topic. That tells me there is no red flag popping up to the normal Creative support guys on the topic. My plan is to build two switches with each one connecting two DIP-8 sockets together, this way you could literally pop back and forth between the op-amps (not quite as simple as it sounds, but that is the general idea).  The problem is, electrically this is the exact same as pulling/inserting them with the power on as described in the OP (which is why I asked the way I did).

 
You seem a bit unwilling to accept advice, but regardless - please let me point out a few things:
 
1. Russian Roulette is not "dangerous" in every scenario, either.  However, you still have at least one chamber with a live round that may rotate into position at any time.  This is perfectly analogous to your "hot swap" proposal.
 
2. Ever tried to find a 8-pole, double-throw switch? There are some special order ones available at Mouser, starting at $524.  (OK, maybe it wouldn't be 8-poles with some shared grounds in there, but maybe you get the idea.)
 
3. Wire leads leading from a switch(es) to multiple opamp pins on two different opamps?  There is so much extra inductance (even a little extra resistance) in those wire leads that the opamps may not even be stable, much less provide any meaningful results of how they would perform in a circuit.  It is decidedly not the same, electrically.

 

[DaveLT]

  Sound like you under the impression hot swapping op-amps in any scenario is dangerous, which isn't true. Op-amps can be used to accomplish a variety of tasks in circuits, so it really depends on what you are building. I haven't built a DAC or headphone amp yet (no time..), so I can't say what what would happen with how they are used in this sound card. Many people assume pulling a transistor with power on is dangerous to the transistor, it's really (possibly) dangerous to the rest of the circuit, not the transistor being pulled.

I do agree with you that it is possible to do it without doing A/B testing, but every reputable review site is using some form of A/B testing (usually double blind A/B). I am looking to start up a review and electrical modding/building site (already have the domain), so I'd like to have semi-professional testing techniques. I do have an oscilloscope which would allow me to actually view/capture the raw output signals for comparison.

I just finished speaking with Creative Inc. and their Engineering Department is going to email their recommendation on this topic. That tells me there is no red flag popping up to the normal Creative support guys on the topic. My plan is to build two switches with each one connecting two DIP-8 sockets together, this way you could literally pop back and forth between the op-amps (not quite as simple as it sounds, but that is the general idea).  The problem is, electrically this is the exact same as pulling/inserting them with the power on as described in the OP (which is why I asked the way I did).

You could pull one halfway up and wind up not pulling the other side up but otherwise, it just cuts power off to the opamp.
 
The biggest worry is putting an opamp in on the wrong pins though.

 

[NCSUZoSo]

Quote:

   
You seem a bit unwilling to accept advice, but regardless - please let me point out a few things:
 
1. Russian Roulette is not "dangerous" in every scenario, either.  However, you still have at least one chamber with a live round that may rotate into position at any time.  This is perfectly analogous to your "hot swap" proposal.
 
2. Ever tried to find a 8-pole, double-throw switch? There are some special order ones available at Mouser, starting at $524.  (OK, maybe it wouldn't be 8-poles with some shared grounds in there, but maybe you get the idea.)
 
3. Wire leads leading from a switch(es) to multiple opamp pins on two different opamps?  There is so much extra inductance (even a little extra resistance) in those wire leads that the opamps may not even be stable, much less provide any meaningful results of how they would perform in a circuit.  It is decidedly not the same, electrically.

What "advice" did you give in your first post that was related to what I am trying to do?  You basically said don't do it; excuse me for not blindly accepting that answer. 

Now I do greatly appreciate what you said in your 2nd post, as this is exactly the type of info I was looking for. I'm going to do some more research on this idea.

Probably the easiest way for me to directly compare op-amps is with my FiiO E12 DIY. You can quickly turn off the unit and pop out an op-amp and try another immediately with the song paused or looping a certain part. Compare that to shutting down a computer and then removing/inserting op-amps inside the case (or remove the card) and then boot back up.
 

  You could pull one halfway up and wind up not pulling the other side up but otherwise, it just cuts power off to the opamp.
 
The biggest worry is putting an opamp in on the wrong pins though.

Do you know this for certain or are you just speaking from experience/knowledge on the subject? I agree the biggest concern here is putting one in the wrong way. 

The only other question I have right now, will removing the 1st stage of the op-amp chain present any danger to the 2nd stage op-amp in the chain?

See image below
 

 

[DaveLT]

 
What "advice" did you give in your first post that was related to what I am trying to do?  You basically said don't do it; excuse me for not blindly accepting that answer. 

Now I do greatly appreciate what you said in your 2nd post, as this is exactly the type of info I was looking for. I'm going to do some more research on this idea.

Probably the easiest way for me to directly compare op-amps is with my FiiO E12 DIY. You can quickly turn off the unit and pop out an op-amp and try another immediately with the song paused or looping a certain part. Compare that to shutting down a computer and then removing/inserting op-amps inside the case (or remove the card) and then boot back up.
 

Do you know this for certain or are you just speaking from experience/knowledge on the subject? I agree the biggest concern here is putting one in the wrong way. 

The only other question I have right now, will removing the 1st stage of the op-amp chain present any danger to the 2nd stage op-amp in the chain?

See image below
 

I am speaking from experience with EEE. Opamps are generally ok with a open circuit, if they weren't we'd blowing input circuitry everytime we unplugged equipment but it really depends.
 
Also, what 1st stage do you mean? the 1st stage looks like SMD to me and you can't remove SMD opamps.

 

[NCSUZoSo]

  I am speaking from experience with EEE. Opamps are generally ok with a open circuit, if they weren't we'd blowing input circuitry everytime we unplugged equipment but it really depends.
 
Also, what 1st stage do you mean? the 1st stage looks like SMD to me and you can't remove SMD opamps.

Funny you mentioned that, I am planning on replacing those surface mount op-amps soon! I have been practicing with my new SM Hot Air Re-Work station (852D+) and I plan to work on the card soon. Any recommendations for SMD  op-amps that are better than the JRC's that are being used?

The big thing about replacing those is you don't want to roll op-amps there.  You need to pick something you know is better than stock for sure.  Unless I want solder in some DIP-8 sockets to the SMD pads!
 
However I was talking about the stage 1 and stage 2 in the yellow boxes.  They didn't label it stage 1 and 2, but it is setup the same as the front/sub and rear channels are with how the op-amps are arranged/used.

By the way, I have already done one hardware mod to my ZXR, so I am not shy about soldering perfectly good hardware

If curious about this mod, see here: http://www.head-fi.org/t/705284/germaniums-sound-blaster-zxr-mod-thread

 

[DaveLT]

 
Funny you mentioned that, I am planning on replacing those surface mount op-amps soon! I have been practicing with my new SM Hot Air Re-Work station (852D+) and I plan to work on the card soon. Any recommendations for SMD  op-amps that are better than the JRC's that are being used?

The big thing about replacing those is you don't want to roll op-amps there.  You need to pick something you know is better than stock for sure.  Unless I want solder in some DIP-8 sockets to the SMD pads!
 
However I was talking about the stage 1 and stage 2 in the yellow boxes.  They didn't label it stage 1 and 2, but it is setup the same as the front/sub and rear channels are with how the op-amps are arranged/used.

By the way, I have already done one hardware mod to my ZXR, so I am not shy about soldering perfectly good hardware

If curious about this mod, see here: http://www.head-fi.org/t/705284/germaniums-sound-blaster-zxr-mod-thread

 
Tbh, that cap mod is just stupid. It just introduces more lead inductance which leads to a worsened reactance which if it makes a difference is negative impact.
 
Also, most opamp upgrades usually won't make any difference. 

 

[Speedskater]

As Jay Leno (he was a late night talk show host & comedian) would say:
"What could possibly go wrong?"

 

[NCSUZoSo]

   
Tbh, that cap mod is just stupid. It just introduces more lead inductance which leads to a worsened reactance which if it makes a difference is negative impact.
 
Also, most opamp upgrades usually won't make any difference. 

 
Say what you want about the mod, but it is one of the most obvious changes in sound I have ever witnessed in my 10-15 years of modding. It brings a warmth to the sound, similar to what a tube amp sounds like compared to an SS amp. Twice as big a difference as all the mods that were thought up for the Aune T1 used at once.

Direct coupling mods aren't uncommon, so I'm not sure why you are acting like it's a bad thing.

(Don't forget about the 12 electrolytic caps on the card I shorted before adding the Erse PulseX caps.)

Anyway, I am working on the review now for Burson Audio. I have confirmation that there is no real danger to the op-amps, but I think I will review them with the E12 DIY and not the ZXR.

 

[DaveLT]

   
Say what you want about the mod, but it is one of the most obvious changes in sound I have ever witnessed in my 10-15 years of modding. It brings a warmth to the sound, similar to what a tube amp sounds like compared to an SS amp. Twice as big a difference as all the mods that were thought up for the Aune T1 used at once.

Direct coupling mods aren't uncommon, so I'm not sure why you are acting like it's a bad thing.

(Don't forget about the 12 electrolytic caps on the card I shorted before adding the Erse PulseX caps.)

Anyway, I am working on the review now for Burson Audio. I have confirmation that there is no real danger to the op-amps, but I think I will review them with the E12 DIY and not the ZXR.

That exactly, is what I mean by "negative" effect. You really need to read up on circuit reactance to know that extended protruding leads are BAD.

 

[Speedskater]

Whenever I handle op-amps or digital chips I follow normal anti-static procedures.