LM741 opamp substitute?

[langleycello]

Greetings,

I am hoping to replace the somewhat dated LM741 opamps in an old 1970s
PKE phono preamp. There are 3 in each channel (6 total). I can post a
close-up pic of the circuit board to anyone who may be happy to comment
specifically. I am hoping to apply a drop-in solution if possible, but
understand that this may not be preferable.

Many thanks,

Stephen

 

[Phil Allison]

"langleycello"

I am hoping to replace the somewhat dated LM741 opamps in an old 1970s
PKE phono preamp. There are 3 in each channel (6 total). I can post a
close-up pic of the circuit board to anyone who may be happy to comment
specifically. I am hoping to apply a drop-in solution if possible, but
understand that this may not be preferable.

** The nearest * readily available * op-amp to replace the venerable LM741
in most audio applications is the TL071.

It is indeed pin for pin and a drop in replacement - much more bandwidth
& slew rate but very similar noise level to the 741.

Need to see a schematic to exclude any ( not very likely ) issues with the
substitution.





........ Phil

 

[Rheilly Phoull]

Greetings,

I am hoping to replace the somewhat dated LM741 opamps in an old 1970s
PKE phono preamp. There are 3 in each channel (6 total). I can post a
close-up pic of the circuit board to anyone who may be happy to comment
specifically. I am hoping to apply a drop-in solution if possible, but
understand that this may not be preferable.

Many thanks,

Stephen

PKE are still active, why not ask them ?
Rheilly P

 

[langleycello]

PKE are still active, why not ask them ?
Rheilly P

Yes, I have, but they no longer have the available info.

Thanks Phil for your suggestion.

For the sake of it, I include some photobucket URLs of one phono card
(back and front) which may cast some extra light on things, in the
absence of a schematic.

http://i16.photobucket.com/albums/b17/langleycello/IMG_2144-1.jpg

http://i16.photobucket.com/albums/b17/langleycello/IMG_2145-1.jpg

Cheers,

Stephen

 

[Phil Allison]

"langleycello"

Thanks Phil for your suggestion.

** " Lament of the 741 "


Why substitute me for another type ?

Have you all fallen for a load of hype ?

I look pretty small but my pins are high

The simple specs you see are all complicated

I may be pretty old but I'm not outdated - yeah ...



Note:

The uA741 first appeared in May of 1968 - it was very expensive.

The TL071 first appeared in July of 1977 - it was dirt cheap.




........ Phil

 

[Lord Garth]

For the sake of it, I include some photobucket URLs of one phono card
(back and front) which may cast some extra light on things, in the
absence of a schematic.

http://i16.photobucket.com/albums/b17/langleycello/IMG_2144-1.jpg

http://i16.photobucket.com/albums/b17/langleycello/IMG_2145-1.jpg

The circuit is easily traced in order to create a schematic. From there you
should be able to update the circuit.

 

[Trevor Wilson]

Greetings,

I am hoping to replace the somewhat dated LM741 opamps in an old 1970s
PKE phono preamp. There are 3 in each channel (6 total). I can post a
close-up pic of the circuit board to anyone who may be happy to comment
specifically. I am hoping to apply a drop-in solution if possible, but
understand that this may not be preferable.

**Assuming no oddball circuit highlights, the OPA604 will do nicely. If you
want to take it further, the AD825 (a carrier PBC will be required) will be
(slightly) better again.

 

[langleycello]

Thanks everyone for your thoughts,

I'll get some 8-pin sockets and opt for a flexible arrangement. Maybe
I'll first experiment with some TL071s, which hopefully should be OK as
an immediate drop in, and then perhaps the OPA604 down the track.

Cheers,

Stephen

 

[Phil Allison]

"langleycello"

Thanks everyone for your thoughts,

I'll get some 8-pin sockets and opt for a flexible arrangement. Maybe
I'll first experiment with some TL071s, which hopefully should be OK as
an immediate drop in, and then perhaps the OPA604 down the track.

** Another low cost & readily available op-amp type that ought not be
ignored is the very famous NE5534P - available from DSE and many others.

It will likely require a 33pF capacitor between pins 5 and 8 to be " unity
gain stable " - as the 741 is inherently.

According to my ( not inconsiderable) experience and also that of renound
pommy audio expert Doug Self, the NE5534 is the lowest noise, best
performing MM phono stage op-amp available.


( MM = moving magnet = high impedance = 47 kohms)




......... Phil

 

[Trevor Wilson]

Whats wrong with the 741?

**Let's see:
* It's noisy
* It has a crappy slew rate.
* There are other, audibly superior devices available.

741s should be removed from almost ANY product which uses them. They work
fine at or near DC, however.

If it aint broke, dont fix it!

**The 741 is already broke.

 

[Trevor Wilson]

Thanks everyone for your thoughts,

I'll get some 8-pin sockets and opt for a flexible arrangement. Maybe
I'll first experiment with some TL071s, which hopefully should be OK as
an immediate drop in, and then perhaps the OPA604 down the track.

**Just a point: With the OPA604 and most other replacement chips (the 5534
is notorious in this regard), you need to ensure that the supply rails are
up to the task. Most other chips consume considerably more current than the
741, although, in absolute terms, we're not talking about a great deal of
current.

 

[Two Bob]

I am hoping to replace the somewhat dated LM741 opamps in an old 1970s

PKE phono preamp. There are 3 in each channel (6 total). I can post a
close-up pic of the circuit board to anyone who may be happy to comment
specifically. I am hoping to apply a drop-in solution if possible, but
understand that this may not be preferable.

Whats wrong with the 741? If it aint broke, dont fix it!

 

[Phil Allison]

"Trevor Wilson"

"Two Bob"

** Big mistake asking Australia's most notorious audiophool plus hi-fi
dealer vampire.

* It's noisy

** EIN = 3 uV ( in 20 kHz bandwidth )

Signal to noise = 110 dB ( unweighted) relative to 1 volt at unity gain.

* It has a crappy slew rate.

** An ignorant audiophool opinion TW gets to keep.

* There are other, audibly superior devices available.

** Another ignorant audiophool opinion TW gets to keep.

741s should be removed from almost ANY product which uses them.

** An ignorant audiophool opinion TW gets to keep.

They work fine at or near DC, however.

** Yawn - all totally irrelevant.

**The 741 is already broke.

** An ignorant audiophool opinion TW gets to keep.

Trevor Wilson
www.rageaudio.com.au

** Do look at the vampire's lair.




........ Phil

 

[Bob Parker]

**Let's see:
* It's noisy
* It has a crappy slew rate.
* There are other, audibly superior devices available.

741s should be removed from almost ANY product which uses them. They work
fine at or near DC, however.


**The 741 is already broke.

Geez - now I understand why the ACS demodulator kit (EA 1993)
doesn't sound so crash hot. I shouldn't have used a 741 to do the
de-emphasis! ;-)

Bob