See post 18!
Only helping...
You did say substitute with another op amp, I agree...
Only helping...
You did say substitute with another op amp, I agree...
Last edited:
OP is named Danny. That's me! And I'm too dumb for scope&sim but do like good audio.
Thanks for inspiring the fun aspect! I'm grateful.
Current search at ST offers chips smaller than soldering iron tip; however, current search at TI offers this:
TL972 +2.7V~12V, 12MHz
TLV272 +2.7V~16V, 3MHz
LM6132 +2.7V~24V, 10MHz
TLV2372 +2.7V~16V, 3MHz
P.S. Meanwhile or long ago, at a big beautiful beach somewhat between the borders of countries Turkey and Greece is this guy wearing shoes, shorts and fishing pack, and he is out fishing on the beach, all day. Young hunky Nick gave his catch to hungry people, didn't mind leaving none for himself, and then as it so happens, the early church walked by to meet Saint Nickolas.
Research is good!
Thanks for the search, I´m too lazy to do that successfully 😉
You seem to have found a couple killer Op Amps.
At least for me, I´d use them in active Guitar/Bass designs.
And you can use the duals in the above preamp he he 🙂
You seem to have found a couple killer Op Amps.
At least for me, I´d use them in active Guitar/Bass designs.
And you can use the duals in the above preamp he he 🙂
Last edited:
Dual. Oops!! I actually needed a monophonic preamp, because: phone > preamp > mini transmitter (with the stereo disabled).
To get the whole house on 1 station, the wee transmitter (in the middle of the house) must run in mono mode to get the range (as far as the porch).
So,
How do I either simply neutralize the unused channel (of LM358); or, make it a parallel output (prettier with sonic signature lost into the output ballast resistance and/or even drive a headphone)? Anyway, need mono output and a few more clues. 😀
P.S. Several TI LM358P arrived in the mail.
Easy, just use one half.
Leave the other unconnected both to input and output; since it´s an inverting amplifier, leaving input unconnected leaves it in unity gain mode, which is the preferred way to "neutralize" an unused Op Amp.
It will be fed anyway, because supply connections are internal, but no big deal.
Ouch!!!
LM358 was never intended to be used, it says so in the very schematic, just a working example; didn´t you find 4 usable TI Op Amps which work from 2.7V up?
That said, and while you order and wait for the "good" ones, build one anyway as-is and test the concept.
It WILL work,even if highs will be nothing to write home about.
That said, and just an anecdote:
a certain Saturday night, about 11PM, my home/shop bell rang like crazy.
I have a famous Blues Club around the corner and a Customer, a harmonica/Harp Blues player had just blown the microphone input , probably connected a speaker out to Mic in (all use 1/4" plugs) : Club stages are dark, loud and chaotic, pot and alcohol certainly do not help, so accidents are common, and input TL072 was blown to pieces.
By sheer chance, I had been finishing and shipping a ton of stuff, and had run out of many components, including TL072, RC4558 and similar.
Customer was desperate, so I fit an LM358 as a stop gap measure, urging him to bring it back next Monday.
As you can imagine, he never ever brought it back.
I have met him a couple times since, he says: "leave as is, I prefer it this way, it sounds smoother".
Who am I to argue?
I might get tempted to put an 1/8w 480K from in+ to in- on the unused channel in order to specifically request that it does nothing for voltage. Is that an okay way to waste the extra channel?
As I'm too dumb for the scope&sim (oh there's proof), then I found 2 usable op-amps on search (the other 2 are very fast, I wanted low gain, there's RF and I'm too daft to compensate the fast things to go slower, so rather should buy the 3MHz parts, and not try to convince? the 12+MHz parts to go slower).
The previous op-amp, I guess, may have shown a slight peak up on the upper left hand corner of square wave test, which is called actuance and such audio-sharpening is Vital to highlight the vocals for movies in home theater but could be a very unpleasant tonality for high-spl music.
I bet that the instrumentalist was so surprised that his tone controls worked correctly for the very first time.
I asked about parallel output because of one old datapoint where Engineers and Audiophiles agree. For the Windows XP computer there was a non-studio M-audio sound card with a silver jack (and more). With headphones or amplifier, that silver jack could reliably do the audiophile thing like black-background or out-of-the-black, which, by description is a dynamics enhancement of Less noise floor than expected. Right behind the silver jack were Two Dual op-amps using Parallel drive. These were either JRC4556 or JRC4560--my memory failed as to which, but there was a jrc,4,5 and 6; and there were two dual op-amps for stereo, really fantastically.
The upmarket audio card may have had clean power attempt; so, we might need that.
The particular model of op-amp is unimportant (the means is important but the model number is not).
The parallel output had wasted a portion of the sonic signature into the output ballast resistance; so that, the distortion never made it as far as that silver jack, where you had plugged in something important.
P.S. On looking at online photos of old sound cards, I swear it was M-Audio Revolution 5.1 that had the parallel op-amp drive for the silver jack.
Five tux cats right up the Christmas tree, trouser flapping bass, and I nearly shat!
I must have miswired the 358, but there was no shortfall of gain.
I must have miswired the 358, but there was no shortfall of gain.
I like your idea of using the LM386/3. Trouble is that none of the documentation is specifically optimized for high quality results with audio replay. However, the physical part itself is very well capable. I will endeavor and make a guess.