Replacing VTB1 Opamp?

Hi Chessrock. Are the LT 1469 and OP275 OpAmps better/more suitable for the output stage only? Would either of these be better than the OPA2134 for the MIC or Line In stages?
 
dickiefunk said:
Hi Chessrock. Are the LT 1469 and OP275 OpAmps better/more suitable for the output stage only? Would either of these be better than the OPA2134 for the MIC or Line In stages?
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I can't really answer that question without knowing more about the design, but for the most part, these are all technically interchangeable, and it would be a matter of dropping them in and seeing how they behave ... but since SP recommended the opa2134, I would imagine that one would be a safer choice at the input.

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chessrock said:
Well, it's not like building a house.

You spend (hopefully) a few hours on it, you're done and you move on.

Generally speaking. It's talking about it in threads like this one that burn a lot of hours. :D

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You're done until you have the burning desire to replace that op amp with a "better" one just one more time....just for that ever so slight improvement in sound. LOL.
 
Good advice

mshilarious said:
OK you need to understand some very basics about opamps before you go crazy with swaps. First off is the package you are replacing (I assume it's DIP-8?). If the opamp you are thinking about isn't 8 pin DIP, it will be a much bigger hassle to swap.

Second, 4580 is a dual opamp. AD845 in the DIP-8 package is single, OPA627 is single. OPA2132 is dual.

Finally, superfast, wide bandwidth opamps can oscillate under the wrong conditions. If the VTB's circuitry isn't set up to deal with that, it's a potential problem.

Also you need to make sure you are swapping in a FET input opamp, which 2134 is (and the others mentioned above too, but double check). You don't want a BJT input opamp in the place of a FET input unless you really know the circuit and what you are doing. You can *usually* swap out a BJT input and replace with FET input on a mic input stage, but elsewhere in a circuit (especially in a mixer), the BJT opamps could be necessary to drive the required outputs.

Is it easy to swap opamps? Well, can you solder? Can you desolder without lifting traces? How robust is the VTB1's PCB? Are the holes plated-through? I don't know the answer to any of those questions, but I've swapped many opamps, even when I wasn't that experienced, and it isn't too difficult, but you should get some experience before you jump in. Find an obsolete PCI card with thru-hole components (an old modem should be good for that) and desolder it for fun.

I have swapped the x134 series into many units, always with little trouble and good results. I've used 2604 too, which chess mentioned. They are fairly similar parts, I think 2604 is a bit quieter and 2134 is lower distortion. Both are good, and much better than 4580.
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Just like to re-quote this fine piece of advice. I've replaced many 45XX/5532 devices with the BB 2134/2604 with great results and zero hassles.

Stick with the unity gain stable devices too.

Regards
 
warble2 said:
You're done until you have the burning desire to replace that op amp with a "better" one just one more time....just for that ever so slight improvement in sound. LOL.
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:D Well, guitar players do it with their tubes. I play bass, and I change my strings - occasionally - and no on gives me too much grief about that!

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Thanks. The reason why I'm asking about the TL072's is someone from Studio Projects has recommended that the OPA2134's and TL072's would be the most suitable to use :confused: I have had different messages from them saying either don't replace the OpAmps at all, use OPA 2134's at the input stage to use an OPA 2134 and TL072's?
 
dickiefunk said:
Thanks. The reason why I'm asking about the TL072's is someone from Studio Projects has recommended that the OPA2134's and TL072's would be the most suitable to use :confused: I have had different messages from them saying either don't replace the OpAmps at all, use OPA 2134's at the input stage to use an OPA 2134 and TL072's?
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That's because any one of them should work ... and which one is best is mostly a matter of opinion.

Not to give any excuses for SP -- I mean, I still don't think they know their asses from their elbos :D -- but in this case, I doubt anyone is deliberately trying to be cryptic. Although actually recommending TL072s .... as an upgrade ??? ... is somewhat puzzling.

It really says a lot when what you have to work with is a piece of equipment that's so bad ... that your "upgrade" essentially takes you from Behringer quality to Mackie quality. :D Maybe rather than component upgrades, we should be talking about upgrading the whole thing by either taking what you can get for it on fleabay, or simply chucking it out the window.


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I'm surprised that the TL072's are not much of an upgrade because Rane are fitting their current MS-1b's with these:confused:
 
dickiefunk said:
I'm surprised that the TL072's are not much of an upgrade because Rane are fitting their current MS-1b's with these:confused:
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What are they actually doing in the circuit though?

I'm shit at reading shcematics but it looks to me as if they're not in the audio path at all (maybe something to do with the overload circuit)?

http://www.rane.com/pdf/ms1bsch.pdf

Maybe MS (or somone else who knows what they're talking about) might give us a better idea.

You know if you’re that interested in how different opamps sound you should really get a load of the ones recommended or any that will work in the circuit and just spend some time comparing. Getting opinions on the net is valuable to an extent but you’re never going to get all the answers unless you listen for yourself.

Personally, I don’t think it’s really worth it but if you’re that intrigued then go for it.

If they’re socketed it should be a doddle, if not then put sockets in, that’s not exactly difficult and DIP-8 sockets are cheap and easy to find. You don’t need any special tools or skills, just a screwdriver to open the thing up, a soldering iron if the existing opamps aren’t socketed and maybe some needle nosed pliers to get the things out.
 
Kevin DeSchwazi said:
You know if you’re that interested in how different opamps sound you should really get a load of the ones recommended or any that will work in the circuit and just spend some time comparing. Getting opinions on the net is valuable to an extent but you’re never going to get all the answers unless you listen for yourself.QUOTE]

Hi, yeah I agree with you but some people have told me that it's not advised to simply swap different OpAmps in because I could permanantly damage the circuit?

The Rane Ms-1b also use MC 33078 OpAmps with the TL072
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I'm not suggesting you just chuck in any opamp that fits that's why i said the ones that have been recommended or that you know will work.

Physically swapping them isn't difficult is all I meant.
 
Ok no worries, that's the reason why I posted this thread. I am looking for advice on what OpAmps would be suitable for using and what peoples experience were with them.
 
Kevin DeSchwazi said:
What are they actually doing in the circuit though?

I'm shit at reading shcematics but it looks to me as if they're not in the audio path at all (maybe something to do with the overload circuit)?
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They are being used as comparators to drive the clipping LEDs :D

TL072 isn't horrible, it works fine, yes, even for audio. A&H uses them in the MixWiz series (at least the v2); some of the other consoles did too. It's just that it isn't a chip you'd swap into something if you were going to the trouble to swap chips.
 
Hi. I spoke to Mick Hinton over at DAV Electronics and he's seen the schemo for the VTB1. He's suggested replacing all the OpAmps with OP275's. I'm gonna try this in a few days and let you know how I found them.
I'm also gonna eventually get round to replacing the capacitors aswell.
 
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