Muroidea | Proco RAT

[apc42069]

First time, long time.. so went as stock as possible given my current stores.

The IC is OP07, and the tranny is 2N5457. Apart from those components, everything else is spec'ed to PPCB BOM.

She chugs. She a fuggin RAT.

Tayda UV printing with varnish gloss on matte grey sand - second pic at an angle showcasing the scuzziness on Rat Fink's tank top/onesie/old timey swimming costume that I was going for.

I'll probably make the suite of mods at some point, and use said tank top/onesie/old timey swimming costume for an area to label which are which.

 

[geoffrey]

I guess this is a question for everybody: how does the OP07 sound compared to a LM308?

 

[steviejr92]

Id imagine the same, I dont think youre going to hear a difference at least to what your ears are going to be able to pick up. @apc42069 Amazing artwork btw! Im really loving the rats face

 

[harmaes]

I recently build a Muroidea and noticed a big difference between a LM308N and a TL071. The latter sounds more open, brighter and less nasal especially on higher gain. The OP07 doesn’t need the 30pf cap BTW. Try the TL071 and see what you think.

The reason I experimented with the opamp was because my Muroidea build sounded more nasally, almost like a cocked wah on higher gain settings compared to an AION Helios build a few years ago. Comparable circuits where the Helios has a Ruetz mod (controls lows and gain) and clipping selection. I’ve also incorporated these in the Muroidea build. Changing to the TL071 because I noticed Brian Wampler using it in his Ratsbane which sounded brighter. I now have an OP07 in my Helios (with no 30pf cap) and the TL071 in the Muroidea.

Hard clipping
If you want a better clean/low gain response use 2 red leds symmetrical or a 1n4148 together with a 5mm red led anti-parallel with a 1n4148. I used a 6-way rotary with the 2 led options. You can select the ones you like from other options like asymm 1n4148, 5mm red led and 1n60, 2 symm low fv germaniums, 2 high fv germaniums, bat46 and 1n4148 anti-parallel with bat46 or 2x bat46 with 1 anti-parallel 1n4148. You can also use bat41 instead of the bat46.
You’ll notice that changing the clipping diodes results in more “compression” and differences in harmonics. I also noticed that the 1n4148+red led anti parallel to an 1n4148 added more nasal frequencies where the bat46 or bat41 combinations tighten up the lows while reducing the output level for instance.

 

[geoffrey]

Great stuff you guys. Thanks!

 

[geoffrey]

Finished my Muroidea as well. NOTHING compared to @apc42069's aesthetically...pretty standard look (and still dusty from the build, as you can see lol).

I tried both a LM308N and a TL071, and there was indeed a wee bit of a difference at high gain, but for me it was negligible (and I have a decent ear I think). Stuck with LM308N for now because I need the TL071 for another project. Will probably experiment further later.

As @apc42069 stated: She chugs. Pure RAT. Love it!

 

[apc42069]

Id imagine the same, I dont think youre going to hear a difference at least to what your ears are going to be able to pick up. @apc42069 Amazing artwork btw! Im really loving the rats face

Thanks dude! Wish I could take credit, but all credit to the late great Big Daddy Roth https://en.wikipedia.org/wiki/Ed_Roth

 

[apc42069]

View attachment 40235Finished my Muroidea as well. NOTHING compared to @apc42069's aesthetically...pretty standard look (and still dusty from the build, as you can see lol).

I tried both a LM308N and a TL071, and there was indeed a wee bit of a difference at high gain, but for me it was negligible (and I have a decent ear I think). Stuck with LM308N for now because I need the TL071 for another project. Will probably experiment further later.

As @apc42069 stated: She chugs. Pure RAT. Love it!

Love it man!

 

[Laundryroom David]

I guess this is a question for everybody: how does the OP07 sound compared to a LM308?

the same

 

[jimilee]

the same

This. If you can hear the differences in those things, you've not been exposed to loud music for many years.

 

[harmaes]

The difference between opamps is more noticable on lower gain.

 

[cdwillis]

Personally, I can tell a difference between a ua741, tl071, and OP07. I can't tell a difference between the OP07 and LM308.

 

[DGWVI]

The difference between opamps is more noticable on lower gain.

The 308 and OP07 both start ducking and gating
at higher gain, most other opamps won't do that without significantly larger compensation caps, if at all

Personally, I can tell a difference between a ua741, tl071, and OP07. I can't tell a difference between the OP07 and LM308.

Same here, though with my current stock of metal cans, the OP07s do seem to have a touch more noise than the 308s/108s I have on hand