Ich bin ein diy'er

thom0911 · 19th August 2011, 06:59 PM

Hello, I'm new to the community and beginning my journey/hobby of diy Audio. I bought an old SM Pro Audio TB202 and looking to replace the Op amps TL084. I have read many posts of possible replacements; TLE2074, LME49740, and AD713.

Can anyone give me some useful info or input on the above referenced Op amps ?

Thanks in advance,
Thom

thaumaturge · 19th August 2011, 09:22 PM

The TLE2074 has a significantly higher noise floor than the others. Given choice I'd choose one of the others. The National looks good.
Doc

thom0911 · 20th August 2011, 01:25 AM

Quote:

Originally Posted by thaumaturge

The TLE2074 has a significantly higher noise floor than the others. Given choice I'd choose one of the others. The National looks good.
Doc

Thanks for the input Doc.. I read some posts indicating that the National was recommedned as well.... Not sure if I would need to change anything else if I were to use the LME49740?

Luke · 20th August 2011, 04:55 AM

und ich machen zwei diy'er

thom0911 · 21st August 2011, 04:59 PM

Truth be told... I don't know a lick of german... other than what I learned from watching Hogan's Heros... My intro was a poor attempt at at humor/history though JFK... I'm a total newbie with an interest and a willingness to learn...

thaumaturge · 21st August 2011, 06:14 PM

Quote:

Originally Posted by thom0911

Not sure if I would need to change anything else if I were to use the LME49740?

From the data sheets the National part looks to be pin for pin compatible. Myself I'd probably swap one as a test case before proceeding.

If you are looking to quiet noise a good look at filter cap ESR might be worth it. Old electrolytics dry out and get higher internal resistance. Very typical source of noise increase. I'd have to take a peek at a schematic or at least maybe some digital pics of the innerds to realistically suggest more.

Doc

thom0911 · 22nd August 2011, 02:19 AM

Quote:

Originally Posted by thaumaturge

From the data sheets the National part looks to be pin for pin compatible. Myself I'd probably swap one as a test case before proceeding.

I'd have to take a peek at a schematic or at least maybe some digital pics of the innerds to realistically suggest more.

Doc

Thanks Doc.. I have been after the schematics for 2 weeks now... the company (SM Pro AUdio) seems to be hesitant to the up... Not sure why

? But I will continue to peter them... hopefully this squeaky wheel will get the oil.. In the Meantime I will post some pics..

Thanks again
-Thom

thom0911 · 23rd August 2011, 12:21 AM

Quote:

Originally Posted by thaumaturge

From the data sheets the National part looks to be pin for pin compatible. Myself I'd probably swap one as a test case before proceeding.

I'd have to take a peek at a schematic or at least maybe some digital pics of the innerds to realistically suggest more.

Doc

Hi Doc... No schematic as of yet but I do have some pics of the inerds for you to take a peek...

Michael Bean · 23rd August 2011, 12:44 AM

The TLO84 is a JFET input device and the National chip is a bipolar input device, it's not really a drop-in replacement, so chances are the National chip won't preform as expected. The AD713, though somewhat dated, is a decent performer, so it would be a better chioce. The problem with "rolling chips" that are significantly faster into an existing circuit is the greater likelyhood there will be oscillation, usually in the MHz range. So unless you're prepared to redesign the existing circuitry to accommodate a different opamp type, stick with something similar to what's already there.

Mike

thom0911 · 23rd August 2011, 01:58 AM

Thanks for the input Mike...

I overlooked posting my pics in my previous thread...

19th August 2011, 06:59 PM	#1
thom0911 diyAudio Member Join Date: Aug 2011 Location: Perkasie, PA	Ich bin ein diy'er Hello, I'm new to the community and beginning my journey/hobby of diy Audio. I bought an old SM Pro Audio TB202 and looking to replace the Op amps TL084. I have read many posts of possible replacements; TLE2074, LME49740, and AD713. Can anyone give me some useful info or input on the above referenced Op amps ? Thanks in advance, Thom

19th August 2011, 09:22 PM	#2
thaumaturge diyAudio Member Join Date: Aug 2011 Location: Utah	The TLE2074 has a significantly higher noise floor than the others. Given choice I'd choose one of the others. The National looks good. Doc __________________ Ne timeas a facie mulierum ea ignorare

20th August 2011, 04:55 AM	#4
Luke diyAudio Member Join Date: Sep 2001 Location: Wellington NZ	und ich machen zwei diy'er __________________ If you give a man a fish he will eat for a day. But if you teach a man to fish he will buy an ugly hat. And if you talk about fish to a starving man then you are a consultant. Dilbert

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21st August 2011, 04:59 PM	#5
thom0911 diyAudio Member Join Date: Aug 2011 Location: Perkasie, PA	Truth be told... I don't know a lick of german... other than what I learned from watching Hogan's Heros... My intro was a poor attempt at at humor/history though JFK... I'm a total newbie with an interest and a willingness to learn...

23rd August 2011, 12:44 AM	#9
Michael Bean diyAudio Member Join Date: Sep 2004 Location: Minneapolis, Minnesota, USA	The TLO84 is a JFET input device and the National chip is a bipolar input device, it's not really a drop-in replacement, so chances are the National chip won't preform as expected. The AD713, though somewhat dated, is a decent performer, so it would be a better chioce. The problem with "rolling chips" that are significantly faster into an existing circuit is the greater likelyhood there will be oscillation, usually in the MHz range. So unless you're prepared to redesign the existing circuitry to accommodate a different opamp type, stick with something similar to what's already there. Mike

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