software

Hey, I'm messing around modding my MXR Distortion , changing the caps, diode configuration, and clipping style, and I'm thinking I might change the IC. What would you recommend? How would a JRC4558 sound in a hard clipping circuit? After doing some research, I came upon these possible chips:LM741 (stock)
JRC4558D (TS808, SD-1)
TL072 (Marshall Blues Breaker, etc)
TL070 (ProCo Rat)
TL07x (070, 071, 072, 073, 074)
RC4558P (TI version of the JRC4558)
RC4559P (Another TI op-amp favored for distortions)
LM1458
What difference would they (whichever ones you know) make in the sound? Which, or if you have any others, would you recommend? I might get a chip socket and try a few out, but I need to narrow this down first.

Thanks.

What UC is not what IC

I have no experience with this, so I can't suggest, that just popped into my head.


Originally Posted by XeromusWhat UC is not what IC
Originally Posted by STRATDELUXER97I did an MXR Distortion pedal for a forum member and I used the TI RC4558P...Sounded great and kept the tone tight and articulate...The JRC4558D is too spongey and soft in that pedal...

Thanks John, exactly what I wanted.

Anyone else?

yo john, what are your 2 favorites, and which do you like best for low gain w/ a TS9 and a strat?

I'm looking to do some swapping for fun to check out new tones, and since these things aren't expensive at all, why not?

Where do you get em? Mouser?


Originally Posted by Quencho092yo john, what are your 2 favorites, and which do you like best for low gain w/ a TS9 and a strat?

I'm looking to do some swapping for fun to check out new tones, and since these things aren't expensive at all, why not?

Where do you get em? Mouser?

Wow this is the 3rd time I've referenced this site in 2 days on the this 'ol forum. from : localhost/. Small Bear has the best prices I've found and they have all kinds of great stuff. I'm just starting to get into pedal building/modding and this place has been great. John told me yesterday that he really liked them too.

Yep, Small Bear's where I plan to get them. I've had great experiences with them with other stuff.

ok ok i got it.

What do they mean the the transistors are GEO spec? Does that mean that they will have their sweet spot at the recommended bias point from GEO's website?

I want to build a rangemaster with these parts, that's all!

^Yep. If you look on the front page they note that they support the projects at GEO, Tonepad, General Guitar Gadgets, and some more.

slick, ill be building a few rangemasters this week then. If all goes well, perhaps ill hook a few of you guys up with deals on my products...lol

^Sounds good.

Can anyone tell me about some of the other op-amps? John, if you've used both, what are the differences between the RC4558P and 4559P?

my guess would be that the 4559P is more of a distortion chip, or get's more gain?

Until John chimes in, I'm all for the RC4558P. Lew likes the RC's i hear, cause they're crispier and more articulate.

I have both and have tryed both and I don't hear any difference that I can mention about the 4559?

Also.....I just looked at my mod notes on the Distortion and I used the 741 chip...The 4558 is a dual opamp and won't work in the MXR unless you jump some pins on the 4558...I used a cheapo radio shack 741 in the MXR I modded,but it was the other stuff I did that made the pedal sound great...

The original LM741 is a frequency compensated single op-amp and it is not, I repeat not compatible with any of the 14/45 series..(1458,4556,4558,4559, 4560.....4580's) nor the TLO bi-fet's......

The pin configurations are not the same, the offset null pins are exclusive to the Lm741 IC's.....

from : localhost/cache.national.com/ds/LM/LM741.pdf

compared to the latest 45 series:

from : localhost/focus.ti.com/lit/ds/symlink/rc4580.pdf

whereas the TLO series (again) being bi-fet have differing operating parameters altogether!

Fwiw...

Jeff Seal


Originally Posted by Jeff SealThe original LM741 is a frequency compensated single op-amp and it is not, I repeat not compatible with any of the 14/45 series..(1458,4556,4558,4559, 4560.....4580's) nor the TLO bi-fet's......

The pin configurations are not the same, the offset null pins are exclusive to the Lm741 IC's.....

from : localhost/cache.national.com/ds/LM/LM741.pdf

compared to the latest 45 series:

from : localhost/focus.ti.com/lit/ds/symlink/rc4580.pdf

whereas the TLO series (again) being bi-fet have differing operating parameters altogether!

Fwiw...

Jeff Seal

Yep.....The 741 is a single opamp....The 4558 is a dual opamp....The 4558 didn't work in the MXR Distortion circuit...

Gracias, guys. I don't know too much about op-amps. What op-amps would I be able to use in that circuit that you think would sound good? Just to experiment.

Thanks.


Originally Posted by Jag513Gracias, guys. I don't know too much about op-amps. What op-amps would I be able to use in that circuit that you think would sound good? Just to experiment.

Thanks.

Pretty much just the 741 opamp in that pedal...As I said,it was all of the smart modding I did on the MXR I did for a friend that made most of the difference and not the opamp....If you really know the circuit well and know where and how to tweak it,you could really have a cooler sounding pedal...Please don't ask for all the mod secrets....