September 8, 2019 at 3:16 pm #6822
I know the Mini-Me calls for an LM358 at IC4 location, but with an identical pinout and nearly the same slew-rate (358 slew-rate = 0.3V/µs and the 1458 has a slew-rate of 0.5V/µs), I should be able to replace the 358 with an LM1458 dual opamp – right?
Or am I better off ordering some LM358 dual opamps?September 8, 2019 at 3:55 pm #6823wilkie1Moderator
Hmm. I think the LM358 has a lower current requirement if I am reading the spec sheets correctly. But since this circuit has 2 separate ground planes, there may not be a noise issue. Otherwise you may be OK.September 8, 2019 at 8:44 pm #6824
Wilkie1 – thanks for that. I examined both datasheets as well and seeing as the current draw difference between them was small, (358 [0.7mA typical, 1.2mA max] – vs – the 1458 [3mA typical, 5.6mA max]), I am thinking along the same lines; considering that opamp is part of LFO circuit and is on a separate ground plane. I just wanted to ask and see if anyone had any experience with this particular opamp x-ref. Still, I’m going to order a few 358s and see what gives when they are exchanged. After I get it built and try out both opamps, I’ll report back. Hopefully before 10:00 next summer. 🙂
</tip-o-the-hat>September 8, 2019 at 8:52 pm #6825wilkie1Moderator
See? Great minds think alike. That means we get into trouble together.September 8, 2019 at 9:07 pm #6826
Wilkie1 – LOL! Sure enough. 🙂
It also occurred to me to ask about the solder side jumper notes for the BBD IC. The notes say that the 3207 is not compatible with this Mini-Me build, but the solder-side has a small note regarding how to place the jumpers for using either the 3007 or 3207 BBD IC. That lends to a bit of confusion on my part. Or is it that the notes in the build docs refer only to the “CoolAudio” version of the 3207 as not compatible?September 9, 2019 at 1:18 am #6829BarryKeymaster
This board version is not officially released yet so you are not reading the correct document. Get with me on details you need depending on chip.October 15, 2019 at 3:02 pm #7102pinkjimiphotonParticipant
i’ve built a bunch of the circuits this was based on, ANY dual opamp should work fine. tl062/72/82 etc.
1458 is a good choice for this if ya really wanna nitpick, but even a 4558 will work about the same. socket the chip, and try whatever you have. if you really feel its not up to par, by all means order the lm358’s, those were spec’d originally cuz they were cheap and abundant for the time when the original analog choruses were built, and pretty low noise by those standards… tho not necessarily by today’s.
the last clone theory i built, i subbed every chip on the board and found literally no tonal difference. higher current requirement chips could be an issue, but in this circuit, i doubt it. op275, 4558, tl0*2,1458, lm358… use what ya have and you should be fine.
the diffs tonally in most opamps is fairly minimal ime.
hope that helps!
PjPOctober 15, 2019 at 5:40 pm #7111
Hiya Pink . . . . Thanks! I was later in the thread referring to the BBD device option on the new PCB. I have a good grasp on the opamps now – they’re not an issue. I have both a 3007 and a 3207, but I’m going with the 3007 BBD chip on this build. I was just surprised to see the option silk-screened on the new PCB. The build docs are not yet completed for the new version of the Mini-Me PCB build.October 15, 2019 at 9:08 pm #7112pinkjimiphotonParticipant
right on, hi CC,
yeah, i’d go that route too. the mn3007 is the proper chip for this kind of circuit anyways, and will get the best tone.
i have a board for this that barry sent me, i hope to getting around to messing with it soon. i’d like to make it even a little more clone theory like, and this is gonna be a great candidate for playing with.
its just like the guitarpcb crew to always be looking for the best possible ways to do it, i’m jazzed they’re offering that option as 3007’s get harder to find.
for info purposes only, the NTE equiv for these style analog choruses actually works pretty well if someone has issues with finding decent 3007’s. i forget the part number, but my original vero clone theory i used one til i got some 3007’s, and there was almost no difference tonally… surprising, with nte stuff!
anyways, nice chatting, glad you’re good with the opamps, and enjoy the build!
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