LM308 & OP07 IC Comparison in ProCo™ Rat™ Replica

This is a comparison between opamps (LM308 and OP07) for those on the cusp of deciding which sounds better in the Rodent offered by http://www.generalguitargadgets.com/ . The original ProCo Rat (tm) came with a 308 leaving many to suggest the original sounded better.

Technical notes:

The circuit in the two pedals is identical. So, too, are the pots used for volume, filter, and gain. I even took great pains as closely match the length of wiring within the box when wiring up the Rodent with the 308 (for the scrutinous ones).

Each pedal has a Duracell battery taken from a brand-new double pack and placed in the pedals at the same time. The voltages on the batteries read identical.

Category:

Music

Tags:

• opamps/IC
• LM308
• OP07
• Rodent pedal
• GGG
• general guitar gadgets
• Carvin
• Les Paul Deluxe
• George Ls
• ProCo Rat.

[matthewcjenkins]

But who uses a rat at low gain?

[jwyatt4]

@matthewcjenkins: Lol, good point.

[taigkyo]

Great & useful demo, thanks for posting this!

[jwyatt4]

@taigkyo Thanks for tuning in. 

[AngrySemite]

Thanks. Useful info. We're really in cork sniffing territory here. I can get way more tonal variation from my picking hand. Interesting, because I found an LM308 in my friend's basement, swapped it into a turbo rat and completely transformed it into a super pedal. Never liked the stock Turbo, but it blows away my original RevB now. The combo of the LM and the diode is nice. Dumb luck. I am a tube guy and had never heard of the LM308 mod.

[jwyatt4]

@AngrySemite Yeah... playing style is definitely a variable that heavily influences tone. Also glad to hear the swap transformed the Turbo into a better sounding pedal. That is awesome and (I suppose) why some of us have become cork-sniffing geeks.

[miguelangelobc]

Man, you just proved that there's no difference between lm308 and op07!!! I listened to ths video several times and didn't notice any difference! Now I believe that the difference between the old Rat and the new Rat that is shown in other videos doesn't occurs due to the op amp that's being used... that warm sound lies on another thing... maybe a capacitor, maybe a resistor, or even a pot!... who knows? any clue? greetings from brazil!

[matthewcjenkins]

@jwyatt4 I've watched the video again and decided they both sound better. :) Just added an OP07 to my Mouser order.

[youzektube]

Honestly?.. don't heard any difference on my pc speakers!

[hithisishal]

I'm surprised that you would get a rolloff from the trebs in the LM308. There is plenty of feedback...I bet the amp could handle it. I don't mean to criticize your methods, but did you use tight tolerance parts in your pedals? I feel like a +/- 10% capacitor somewhere in the feedback circuit is more likely to influence tone, but I could be wrong about that.

I wonder what an older, "worse" opamp would sound like...something like a 741.

Thanks for posting!

[jfrizzlle]

not big enough of a difference to justify saying the lm308 is better

[DarkAngelEU]

it's barely there, but yeah I can hear a difference.. I can choose to buy a new RAT2 or a vintage one (with the LM308 in it), guess I'm gonna go with the vintage one ;)

[askwho69]

Op07 is a little bit compress rather than LM308 ! but its a tiny winny can hear it if your not focusing on it