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Quotes From The TI Site

65.12.113.3

In Reply to: RE: Op-amp = Slop Amp? posted by djk on June 29, 2007 at 18:37:56

"The TLE207x series of JFET-input operational amplifiers more than double the bandwidth and triple the slew rate of the TL07x and TL08x families of BiFET operational amplifiers."

And a feature which was important to me, "Direct Upgrades to TL05x, TL07x, and TL08x BiFET Operational Amplifiers"

I'm not normally a spec chaser, but this seemed like a good upgrade to me, especially since TI says it's a direct replacement. I'm no expert, and when my fellow tweaks suggest "well, it should work, but it MAY oscillate" I get a bit uncomfortable.

I assumed that if nothing else, it would improve the performance (if not the sound) of the amp. And it very well may have, but at the expense of bottom end control...at least so far. And in a subwoofer amp, giving up the bottom doesn't make any sense.

I'll post again once I've used the amp for a while.

Thanks.

Follow Ups:

Could you explain why - clifff 13:15:57 07/01/07 (8)
you are worrying about the slew rate performance of an op-amp in a sub-woofer than rolls off at (say) 200Hz ??

A complete mis-hit, IMO.
- RE: Could you explain why - 1973shovel 18:01:22 07/01/07 (7)
  Could I explain why? Honestly, no, I couldn't. Not in terms of "the increased slew rate will cause the amp to perform in a more liner parameter at 80 CPS because blah blah blah".
  
  I'm no expert, and don't pretend to be. I'm a music lover, kit builder, and parts upgrader. If the experience of many posters is that upgrading a 4558 op-amp to a 2604 results in better sound, with rarely a problem, I consider giving it a try.
  
  In this case, the Texas Instruments web site says the TLE2072 is a direct replacement for the TL072 which was in my amp, and it's a better performer. Who am I to argue with TI? For $2.25 it was worth a shot.
  
  I hope I don't sound rude in my reply. That's certainly not my intent. It seemed easy and cheap, and it was. It also may have been the complete mis-hit you describe. But I figured the "mis-hit" would be in the form of overkill, and no sonic change, rather than a somewhat degraded performance.
  
  If there was no audible change from the increased slew rate and bandwidth of the new op-amp I never would have posted. It was the "better part = worse sound" that made me ask the question.
  - RE: Could you explain why - nightdoggy 07:56:02 07/02/07 (6)
    I'm sure that op amp changeout is much more audible then say the differences between two audiophile polypropylene caps. The TL2072 is orders of magnitude "better" than the ancient (30 year old) TL072.
    For a couple of bucks, why not? I might be hesitant to go with a $25 op amp, but I'd still be tempted.
    Also get rid of that 4558 as fast as you can.
    It's bothering me and It's not even mine!
    LOL
    doggy
    - get rid of that 4558 as fast as you can - 1973shovel 18:51:42 07/02/07 (5)
      I've got a couple of AD827's I took out of the JVC 1050 a few months ago which I replaced with OPA 2604's.
      
      Think the 827 would work in place of the 4558 or should I wait and order another 2604?
      - RE: get rid of that 4558 as fast as you can - nightdoggy 02:29:03 07/03/07 (4)
        
        In Reply to: RE: get rid of that 4558 as fast as you can posted by 1973shovel on July 02, 2007 at 18:51:42
        
        I'm sure it will be fine. I don't know what purpose your 4558s serve. I have Luxman tuners that use them to drive signal strength LEDs.
        
        RE:I have Luxman tuners that use them to drive signal strength LEDs. - 1973shovel 03:11:51 07/03/07 (3)
        
        In Reply to: RE: get rid of that 4558 as fast as you can posted by nightdoggy on July 03, 2007 at 02:29:03
        
        And you lef them in?!! Oh my gash! LOL!
        
        Below is a section from my original post on the function of the 4558 in my subwoofer amp. Looks (and sounds!) to me as if it's in the signal path.
        
        When Stereophile reviewed this amp in 1994, during the bench-testing phase they reported "amplifier's low-pass crossover functions, implemented using 4558 dual op-amp chips..",
        
        To tell you the truth, it's the other chip (the TL072) which I'd like to know the function of, now that I've played with it.
        
        Doggy, thanks for all your input!
        
        Actually I ripped it out of both tuners! - nightdoggy 16:12:23 07/03/07 (2)
        
        In Reply to: RE:I have Luxman tuners that use them to drive signal strength LEDs. posted by 1973shovel on July 03, 2007 at 03:11:51
        
        And stomped up and down on them and then dropped the remnants down into the sewer in front of my house!
        Actually I stole a bunch of OP270EZ (ceramic dips-nice!) op amps from work and used those.
        The OP270 is a great op amp for dc applications like that and less than ideal for ac applications.
        It is a hundred times better than the RC4558.
        Yes, a hundred times exactly!
        Gotta go, my cat just ran by me with another mouse in her chops.
        doggy
        
        RE: my cat just ran by me with another mouse in her chops - 1973shovel 04:38:03 07/04/07 (1)
        
        In Reply to: RE: Actually I ripped it out of both tuners! posted by nightdoggy on July 03, 2007 at 16:12:23
        
        Did the mouse have a 4558 in his chops? That's some well trained cat you have there doggy!
        
        She left the last corpse on my bed! - nightdoggy 09:28:39 07/04/07 (0)
        
        In Reply to: RE: my cat just ran by me with another mouse in her chops posted by 1973shovel on July 04, 2007 at 04:38:03
        
        Kinda gross but I guess she loves me!

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