[sdiy] TL072??

Thu Jun 12 09:08:01 CEST 2014

In my opinion, the tiny differences I saw in the datasheet between TL07XC
and TL08XC (the only grades where there were differences in anything except
CMRR) would never be noticed in any normal application.

I still say they are interchangeable.

> -----Original Message-----
> From: Dan Snazelle [mailto:subjectivity at hotmail.com] 
> Sent: Wednesday, June 11, 2014 11:46 PM
> To: David G Dixon
> Cc: Tim Ressel; Synth-Diy
> Subject: Re: [sdiy] TL072??
> 
> david... i see here you said two things which relate to the 
> question of What the differences are between the two opamps
> 
> at first i thought you said they ARE interchangeable ( which  
> for me means you can safely switch them on a BOM with no 
> detrimental effects )
> 
> but then I saw that before that you did a great job of 
> listing the three "small" differences some of which you said 
> are in the cheaper versions (which many people use) 
> 
> but those small differences can matter in situations where 
> those specs were crucial to something working : current draw 
> limited situations, repair situations or people ordering kits 
> which ask for 82s or 72s ( i would never want a population 
> place to switch 72s to 82s or vice versa as that is throwing 
> enough difference into a circuit which might use 5-10 tloxx 
> chips...which could cause sub-optimal operation
> 
> and since they are all so low in price, i always keep 72s and 
> 82s on hand (and of course 62s)
> 
> i guess i just wanted Tim to know that there is definitely 
> SOME difference thats all
> 
> 
> 
> funnily enough, tonight I stumbled across a repair techs 
> blog... when i found someone else who has had issues helped 
> by switching from 72s to 82s ...ultimately he went to a 62 
> but i think it gives more credence to the idea that 72s and 
> 82s are not always exactly the same.
> 
> anyway its a funny anecdote about why keeping all three 
> around is useful! ( well we all know 62s are great for many 
> apps anyway)
> 
> korg polysix repair: 
> 
> Another day dawned, and the keyboard was taken out once again 
> to allow test equipment access to the oscillator section. 
> Apart from the K30A O FET, everything in voice 5 was brand 
> new but also of the original type. In a moment of desperation 
> we replaced the TLO72 with a TLO82 just to see what 
> difference it made.
> It did make a difference, voice 5 was now sharp, we thought 
> great, trim it down and job done.
> Not so, when voice 5 was flat, the tune low trimmer ran out 
> of track before tuning was achieved, when it was sharp the 
> same thing happened at the other end of the trimmer.
> We next tried a TLO62, and in a Goldilocks moment, it was just right."
> 
> 
> (from here:
> http://retroactivesynth.com/index.php?page=march-2011
>    
> 
> Sent from my iPad
> 
> > On Jun 11, 2014, at 3:54 PM, "David G Dixon" 
> <dixon at mail.ubc.ca> wrote:
> > 
> > The slew rate specs are identical for 8X and 7X.  The input current 
> > specs are actually a little better for 8X.  All the other specs are 
> > more or less identical, except that the very lowest grade 8X are a 
> > little lower than the lowest grade 7X on the input voltage 
> specs, and 
> > the CMRR spec for 8X is slightly lower generally (86dB vs 100dB).
> > 
> > Verdict: they are interchangeable.
> > 
> > 
> >> -----Original Message-----
> >> From: Dan Snazelle [mailto:subjectivity at hotmail.com]
> >> Sent: Wednesday, June 11, 2014 9:11 AM
> >> To: David G Dixon
> >> Cc: Tim Ressel; Synth-Diy
> >> Subject: Re: [sdiy] TL072??
> >> 
> >> they are not always interchangeable
> >> 
> >> at least not in terms of certain applications.
> >> 
> >> i can think of at least one case of my own and im pretty 
> sure others 
> >> have told me of cases where they needed an 82 vs 72 or 
> vice versa. ( 
> >> my instance was involving a product of mine and in the BOM 
> there is 
> >> an 82) where a. 82s (poorer?) performance versus the 72 was more 
> >> desirable.
> >> 
> >> (it was in an lfo btw)
> >> 
> >> however this was NOT based on a noise consideration but, I seem to 
> >> recall (this was waaaay back in 2009) based on either slew or 
> >> current.
> >> 
> >> 
> >> maybe verbos can remember ?
> >> 
> >> 
> >> best
> >> 
> >> 
> >> 
> >> 
> >> Sent from my iPhone
> >> 
> >>>> On Jun 11, 2014, at 12:23 AM, "David G Dixon"
> >>> <dixon at mail.ubc.ca> wrote:
> >>> 
> >>> I think they're interchangeable. 
> >>> 
> >>>> -----Original Message-----
> >>>> From: synth-diy-bounces at dropmix.xs4all.nl
> >>>> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of
> >> Tim Ressel
> >>>> Sent: Tuesday, June 10, 2014 9:04 PM
> >>>> To: Synth-Diy
> >>>> Subject: [sdiy] TL072??
> >>>> 
> >>>> Hi,
> >>>> 
> >>>> Someone please explain to me the difference between the
> >> TL072 and the
> >>>> TL082. I keep hearing about its low noise, but according to the 
> >>>> datasheets the noise is identical, as is the input 
> offset current.
> >>>> The input bias current is actually higher on the TL072.
> >>>> 
> >>>> I don't get it.
> >>>> 
> >>>> 
> >>>> 
> >>>> Tim Ressel
> >>>> Circuit Abbey
> >>>> 503-750-9331
> >>>> timr at circuitabbey.com
> >>>> _______________________________________________
> >>>> Synth-diy mailing list
> >>>> Synth-diy at dropmix.xs4all.nl
> >>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> >>> 
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