Op Amp upgrade

[carvinbassplyr]

I have an SWR SM900 and I'm looking to improve the quality/clarity of the preamp. I know thet used TL072 chips which alot if people say are "OK" but not the greatest sounding overall...I know "back in the day" even the "in-house" SWR guys were replacing their op amps right off the shelf but I can't find any info as to what they used now that fender has taken over. I recently did a session through an avalon AD2022 and was simply stunned by the clarity and tone with no EQ and am now unsatisfied with the murky "colored" tone of the SWR. I know it will never sound like an Avalon, but I know putting nicer op amps would help. I'd prefer "drop in" ones that would work without having to revamp other circutry...any help would be great!

[WingKL]

The TI TLE2072 is a direct upgrade substitute for the TL072. It cut the noise in my Thunderfunk by at least half if not more and made it clearer. I think this is the opamp upgrade you're looking for.

[carvinbassplyr]

What did it do for the, if anything, for the tone of the amp?

[BassmanPaul]

Most often just changing out the op-amps will not accomplish all that much. It tends to be the ancillary components that contribute as much or more noise than the devices themselves.

[greenboy]

Originally Posted by BassmanPaul

Most often just changing out the op-amps will not accomplish all that much. It tends to be the ancillary components that contribute as much or more noise than the devices themselves.

Indeed. Often, changing out the player component has the most marked effect on signal quality.

[Matt Dean]

Originally Posted by greenboy

Indeed. Often, changing out the player component has the most marked effect on signal quality.

That was funny...

[lowfreqgeek]

Couple things come to mind. First, the "SWR Sound" is essentially a passive tone stack that is built into the preamp - the Aural Enhancer. Just changing out opamps won't do anything to change the AE circuit. Second, the bipolar preamp supply is severely current limited and can not supply enough current for the high-end audio-grade opamps in every position. Third, not every opamp really needs to be changed. The most important would be the initial gain stage, where you want a very low noise opamp.

But in general, you're not going to make an SM900 or any SWR sound like an Avalon - and certainly not by replacing opamps. I agree that the Avalon in an amazing piece of gear - I used to have a U5 and wish I still did, but I also found that the DI on my Bass 350 was actually less colored than the U5 when I run it direct. The Avalon has it's own "tone stack", whereas there's only a 12ax7 tube and then an electronic differential driver (opamp) in the SWR DI, so not a lot to get in the way (unless you run it post-EQ).

Even my fancy-schmancy Epifani UL502 uses TL0xx opamps throughout. It sounds totally different than the SWR, and more like the Avalon.

[billfitzmaurice]

Originally Posted by carvinbassplyr

What did it do for the, if anything, for the tone of the amp?

Chip swapping won't change tone. It might increase the signal to noise ratio, but unless it's got really cheap 741 family chips chances are the resistors are the major noise source.

[seamonkey]

Originally Posted by carvinbassplyr

I have an SWR SM900 and I'm looking to improve the quality/clarity of the preamp. I know thet used TL072 chips which alot if people say are "OK" but not the greatest sounding overall...I know "back in the day" even the "in-house" SWR guys were replacing their op amps right off the shelf but I can't find any info as to what they used now that fender has taken over. I recently did a session through an avalon AD2022 and was simply stunned by the clarity and tone with no EQ and am now unsatisfied with the murky "colored" tone of the SWR. I know it will never sound like an Avalon, but I know putting nicer op amps would help. I'd prefer "drop in" ones that would work without having to revamp other circutry...any help would be great!

I doubt there'd be much if any change. Op amp designs use a lot of feedback to equal things out.

It shouldn't be a problem to try different chips. I think the old SWR's had chip sockets on hand soldered circuit boards. You can search for replacements or alternatives - seems to be all over google. Other component may matter more, Maybe many more components.

Why not get an avalon AD2022 and run it in the effects return and bypass the SWR pre-amp.

Or just try some other pre's.

[carvinbassplyr]

I would love to run that avalon...but it's almost $3k and is only a preamp...that's twice as much as most of the "top of line" bass heads

[BassmanPaul]

Originally Posted by carvinbassplyr

I would love to run that avalon...but it's almost $3k and is only a preamp...that's twice as much as most of the "top of line" bass heads

And that's why it sounds better than most top of the line bass heads!

[UncleFluffy]

Originally Posted by greenboy

Indeed. Often, changing out the player component has the most marked effect on signal quality.

Ah, PEBKAC, as we'd say in the software world

[BogeyBass]

Doubt they are using sockets anymore for those opamps
its surface mount. So it would be a royal pain to change them for very little change in sound.

With all the EQ options available on a SM 900 it could just be your settings that muddy up the tone.
Sorry guys the SWR has nothing close to a passive "tonestack"
blah blah blah.
Its the problem with the sweepable parametric bands that SWR's offer....and 8 times out of 10.....its to many options and users tend to dial in weird muddy tones. The only thing close to a tonestack is the Bass and Treble controls...which are plain jane active shelving filters....blah blah again nothing close.

To the OP its not that i doubt your EQ settings or skills...it just happens.
And i highly suggest you set your ego to the side and actually try the recommended tone settings in the manual it might help you understand the EQ better instead of blindly going at it with your ears. In the PDF manual , pages 10 and 11 have tone charts and a recommend trying all of them.

Otherwise Electronic wise.....

The big culprit is most likely the Single tube for the preamp...
The low cost tubes that come from the factory are not so great from the start....and if its still in there.

I highly recommend changing it.....even if its "new"
with a high quality 12AX7.

which means to Not just buy another cheap china "Groove Tube" at the music store.

[Jerrold Tiers]

Just piling on.......

The opamps won't do much....... most opamps, including the TL072, are free of major issues*, and a bass pre is NOT an audiophile device......... not that 90% of the "audiophiles" have a clue whether they think the latest gizmo sounds better anyway.... you can sell them anything by implying they have cloth ears if they don't hear the imaginary improvement that YOUR device provides.... "well, you probably are just not an XYZ customer, you seem perfectly happy with a lower priced amp, and that's OK"......

I see folks here fussing over certain things that don't matter, while ignoring the things that do....... and I have heard really good players get amazing sound out of actually bad amps...... Way back a long time ago I quit asking really good players to check out a new amp until we were pretty darn sure it WAS good..... They were totally unreliable as testers, EVERYTHING sounded good.

* Noise is an exception, BUT, watch out for noise vs high impedance..... sometimes all is not as it seems.

[carvinbassplyr]

Originally Posted by BogeyBass

Doubt they are using sockets anymore for those opamps
its surface mount. So it would be a royal pain to change them for very little change in sound.

With all the EQ options available on a SM 900 it could just be your settings that muddy up the tone.
Sorry guys the SWR has nothing close to a passive "tonestack"
blah blah blah.
Its the problem with the sweepable parametric bands that SWR's offer....and 8 times out of 10.....its to many options and users tend to dial in weird muddy tones. The only thing close to a tonestack is the Bass and Treble controls...which are plain jane active shelving filters....blah blah again nothing close.

To the OP its not that i doubt your EQ settings or skills...it just happens.
And i highly suggest you set your ego to the side and actually try the recommended tone settings in the manual it might help you understand the EQ better instead of blindly going at it with your ears. In the PDF manual , pages 10 and 11 have tone charts and a recommend trying all of them.

Otherwise Electronic wise.....

The big culprit is most likely the Single tube for the preamp...
The low cost tubes that come from the factory are not so great from the start....and if its still in there.

I highly recommend changing it.....even if its "new"
with a high quality 12AX7.

which means to Not just buy another cheap china "Groove Tube" at the music store.

I have tried all of them...I was very happy with my SWR until I played through the avalon. The problem is dead flat SWR's sound harsh and honky with alot of upper mids...the avalon flat sounded like a post processed smooth clean andrew gouche/marcus miller tone...and that's what irritated me! I have to do quite a bit of tweaking to get even close that kind of tone from an SWR. So I don't believe "ego" is the issue here...I just never realized how lacking a "professional" level preamp was to studio equipment.

[fdeck]

As I recall, SWR has a "scooped" voicing when its EQ knobs are centered. That could be most of what you're experiencing. With bass gear, nothing is dead flat unless you've measured its response curve for yourself.

[greenboy]

Originally Posted by fdeck

As I recall, SWR has a "scooped" voicing when its EQ knobs are centered. That could be most of what you're experiencing. With bass gear, nothing is dead flat unless you've measured its response curve for yourself.

And then you have to suspect user error ; }

[solarplexus]

Changing the IC could improve the noise, but not the tone. If you really want to swap them, buy a socket and try different IC's. Make sure to record each IC to compare recordings, otherwise you'll have a hard time finding one that does make a difference. I had modded a Boss GE-7 with IC's and did get lower noise depending on the IC. You should look at the NE5532.

[carvinbassplyr]

Originally Posted by fdeck

As I recall, SWR has a "scooped" voicing when its EQ knobs are centered. That could be most of what you're experiencing. With bass gear, nothing is dead flat unless you've measured its response curve for yourself.

I understand that...even when I owned an Eden Highwayman 500 I could never run it flat (despite the companies claims of being able to "run it flat and set ur gain for amazing tone"). I really think the problem is that the avalon is ALL solid state where as the SWR has a tube preamp which adds mud, or "warmth" as some people like to call it, to the sound.

[carvinbassplyr]

Originally Posted by WingKL

The TI TLE2072 is a direct upgrade substitute for the TL072. It cut the noise in my Thunderfunk by at least half if not more and made it clearer. I think this is the opamp upgrade you're looking for.

Which sub-model? When I click on that it takes me to a page that has so many different version I can't even take an educated guess...