Thanks for the help guys. I'm pressed for time and I only have a few op-amp on hand. They are the more basic/older versions such as the 741.
Don't waste your time and energy on using the 741's.
You can still good Dual BI-FET's at your local Radio shack.
Jer 🙂
You can still good Dual BI-FET's at your local Radio shack.
Jer 🙂
The radio shacks around here don't have any fets. I have a few other op-amps, 741, 358, and one that is a dual. I'll have to check to see exactly what I have but they are all basic.
The LF358 is good and it is much better than a 741.
http://www.ti.com/lit/ds/symlink/lm158-n.pdf
Many times I have gone there to get a Tl072 or TL082 and the LF356 or LF353 was what I got in the package.
http://www.ti.com/lit/ds/symlink/lf357.pdf
http://www.ti.com/lit/ds/symlink/lf353-n.pdf
The catalog says the NTE7141 is the equivalent to 4558 which is just as good if not better than a TL07/8xx opamp if that is what it is.
NTE states it is the equivalent to a LM1458, I guess, but that will still work better than a 741 if they have those.
http://www.ti.com/lit/ds/symlink/lm1458.pdf
http://pdf.datasheetcatalog.com/datasheet/nte/NTE7141.pdf
You will have a cleaner sound and much less Noise (hiss) with these better opamp's than you will get with the LM741.
jer 🙂
http://www.ti.com/lit/ds/symlink/lm158-n.pdf
Many times I have gone there to get a Tl072 or TL082 and the LF356 or LF353 was what I got in the package.
http://www.ti.com/lit/ds/symlink/lf357.pdf
http://www.ti.com/lit/ds/symlink/lf353-n.pdf
The catalog says the NTE7141 is the equivalent to 4558 which is just as good if not better than a TL07/8xx opamp if that is what it is.
NTE states it is the equivalent to a LM1458, I guess, but that will still work better than a 741 if they have those.
http://www.ti.com/lit/ds/symlink/lm1458.pdf
http://pdf.datasheetcatalog.com/datasheet/nte/NTE7141.pdf
You will have a cleaner sound and much less Noise (hiss) with these better opamp's than you will get with the LM741.
jer 🙂
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When does the lm741 reach it's 50th birthday?
IC design and performance moves along just like CPU technology.
Would any one dream of using an almost 50year old computer?
IC design and performance moves along just like CPU technology.
Would any one dream of using an almost 50year old computer?
Ahhhh,ha,ha,ha,ha,ha...Excellent Point Andrew!!! 🙂
The LM741 was first released in 1968!!
It is the improved version of the Lm101 that came out a year before.
The very first opamp was the uA702 in 1963, and then then the uA709 in 1965.
I still of some 741's in a metal can.
I First cut my teeth on opamps in 1976 with the LM324 quad versions that were only out for 4 years at the time.
Then shortly after that in about 1978-9 the good ole' TL07x's hit the scene and they are 100 times better than the LM741.
They are still great for using today even though some of the newest ones are as much as 1000 times better than that now.
Operational amplifier - Wikipedia, the free encyclopedia
http://www.diyaudio.com/forums/parts/210860-time-line-dual-8pin-op-amp-development.html#post2987176
jer 🙂
The LM741 was first released in 1968!!
It is the improved version of the Lm101 that came out a year before.
The very first opamp was the uA702 in 1963, and then then the uA709 in 1965.
I still of some 741's in a metal can.
I First cut my teeth on opamps in 1976 with the LM324 quad versions that were only out for 4 years at the time.
Then shortly after that in about 1978-9 the good ole' TL07x's hit the scene and they are 100 times better than the LM741.
They are still great for using today even though some of the newest ones are as much as 1000 times better than that now.
Operational amplifier - Wikipedia, the free encyclopedia
http://www.diyaudio.com/forums/parts/210860-time-line-dual-8pin-op-amp-development.html#post2987176
jer 🙂
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This is funny as last semester I did a Power point presentation on Linear integrated circuits, and the op-amps were a big part of it. The first widely used analog circuit was the ua700. After the Power point, we built the inside of the 741 using all bjts.
Ok, after looking through my chips I have a 358, 392, 741, 324, and one that I don't think will help is drv134pa.
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The DRV134 won't be any good unless you are making a Bridged (or BTL) amp.
The LF358 is decent quality opamp.
I have yet to use a LM392 as they are a bit different.
One has a open collector output stage and is meant to be used as a comparator.
http://www.ti.com/lit/ds/symlink/lm392-n.pdf
You should have Okay results with the LM358, go with those if that is what you have.
It has very low slew rate but since you are using for a sub filter this shouldn't present to much for a problem.
At least using the LM358 you can later swap it out for a better opamp when you get one, providing that you are using an IC socket.
jer 🙂
The LF358 is decent quality opamp.
I have yet to use a LM392 as they are a bit different.
One has a open collector output stage and is meant to be used as a comparator.
http://www.ti.com/lit/ds/symlink/lm392-n.pdf
You should have Okay results with the LM358, go with those if that is what you have.
It has very low slew rate but since you are using for a sub filter this shouldn't present to much for a problem.
At least using the LM358 you can later swap it out for a better opamp when you get one, providing that you are using an IC socket.
jer 🙂
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I haven't come across any two input low pass op-amp circuits for the lm358. Some are single input. I'm new to op-amps, so if the chip is similar enough could I just use it instead?
With the single input, is it really an two input and I'm just supposed to know? Or Will one channel work for one sub out?
With the single input, is it really an two input and I'm just supposed to know? Or Will one channel work for one sub out?
I am not sure exactly what you are asking there are 100's of examples in the links I provided, an opamp is an opamp, some perform better than others.
Most all PDIP Dual opamp's have the same pinout and they are interchangable as long as they have a high enough voltage rating for your circuit.
Some opamp's such as the TLC07x series are only good for up to 16v (+/-8v) total, I have blown a few of these due to forgetting about their voltage ratings!
Always check the data sheet for whatever part you chose to use as some only are good for up to 3v and/or 4.5v to 7v or so.
There are some exceptions to this rule such as some parts that LT makes and some of the SOIC packages have a different pinout as well.
But for the most part with the components we are talking about here have the common pinout that is pretty much the standard.
If you are new to opamp's then this link from Microchip will be of great value to you,
Introduction to Op-Amps - Developer Help
Maybe this diagram can help you and shed some light on the subject,
http://4.bp.blogspot.com/-X5V5isNLZsA/Ta08HwcyiwI/AAAAAAAAAPI/nS88_C5WMuo/s400/Subwoofer+Channel.JPG
It shows that the First section is a two input mixer (signal summing), and, that stage could actually be not used by feeding each R&L signal through their own series resistor directly into the input of the filter stage.
But, It is common and good practice to use a buffer stage to the input of the filter as it is shown in the diagram.
Jer 🙂
Most all PDIP Dual opamp's have the same pinout and they are interchangable as long as they have a high enough voltage rating for your circuit.
Some opamp's such as the TLC07x series are only good for up to 16v (+/-8v) total, I have blown a few of these due to forgetting about their voltage ratings!
Always check the data sheet for whatever part you chose to use as some only are good for up to 3v and/or 4.5v to 7v or so.
There are some exceptions to this rule such as some parts that LT makes and some of the SOIC packages have a different pinout as well.
But for the most part with the components we are talking about here have the common pinout that is pretty much the standard.
If you are new to opamp's then this link from Microchip will be of great value to you,
Introduction to Op-Amps - Developer Help
Maybe this diagram can help you and shed some light on the subject,
http://4.bp.blogspot.com/-X5V5isNLZsA/Ta08HwcyiwI/AAAAAAAAAPI/nS88_C5WMuo/s400/Subwoofer+Channel.JPG
It shows that the First section is a two input mixer (signal summing), and, that stage could actually be not used by feeding each R&L signal through their own series resistor directly into the input of the filter stage.
But, It is common and good practice to use a buffer stage to the input of the filter as it is shown in the diagram.
Jer 🙂
Attachments
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In that diagram you posted, I could just use a lm358 instead of the chip used? Exactly as shown?
And some schematics have only one input, so I'm a little confused there. Does it only take one input or is there two combined and I'm supposed to know that?
And some schematics have only one input, so I'm a little confused there. Does it only take one input or is there two combined and I'm supposed to know that?
Yes, you can use the 358 just the same.
And then later you can just swap it out for a higher quality opamp at will, if you wish.
If you are only building one sub channel then you should use a two input mixer (summing circuit) to combine the L&R signals as Andrew pointed out.
See these pages on how summing or mixer circuits work,
Circuit Idea/Parallel Voltage Summer - Wikibooks, open books for an open world
http://www.electronics-tutorials.ws/opamp/opamp_4.html
If you are using a stereo sub setup then you only need two sub filter sections, one for the left and one for the right.
One dual opamp can be used for whichever configuration you chose to use.
jer 🙂
And then later you can just swap it out for a higher quality opamp at will, if you wish.
If you are only building one sub channel then you should use a two input mixer (summing circuit) to combine the L&R signals as Andrew pointed out.
See these pages on how summing or mixer circuits work,
Circuit Idea/Parallel Voltage Summer - Wikibooks, open books for an open world
http://www.electronics-tutorials.ws/opamp/opamp_4.html
If you are using a stereo sub setup then you only need two sub filter sections, one for the left and one for the right.
One dual opamp can be used for whichever configuration you chose to use.
jer 🙂
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Thanks I appreciate the help. I will use one lm358 to build the audio mixer. It shows three inputs for the mixer for the second site posted, but I figure two inputs, L and R , should work.
I'm going to build my third amp tomorrow at school. I will eventually post some picks.
P.s I ordered some TL082's from TI, should get those soon.
I'm going to build my third amp tomorrow at school. I will eventually post some picks.
P.s I ordered some TL082's from TI, should get those soon.
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You can add as many inputs as you want but you only need Two.
Those two links I posted explain how it works.
Cool, Good deal on getting the TL082's.
For future reference the LME49xxx series (72x,860 and 990) and the LM4562 are the best you can get for audio now and they also have the same pinout.
TI will send them, I have a few of those too.
Cheers!!
jer 🙂
Those two links I posted explain how it works.
Cool, Good deal on getting the TL082's.
For future reference the LME49xxx series (72x,860 and 990) and the LM4562 are the best you can get for audio now and they also have the same pinout.
TI will send them, I have a few of those too.
Cheers!!
jer 🙂
post90 can be simplified.
The first opamp and all it's resistor can be deleted.
Duplicate R5. Each R5 is an input to the inverting opamp that follows.
The output is the SUM of the two input signals times the gain of the stage.
The gain is set by the ratio of R7:R5, i.e. the Output is four times the left channel input = right channel input, or two times the Sum of the L+R input signals.
The first opamp and all it's resistor can be deleted.
Duplicate R5. Each R5 is an input to the inverting opamp that follows.
The output is the SUM of the two input signals times the gain of the stage.
The gain is set by the ratio of R7:R5, i.e. the Output is four times the left channel input = right channel input, or two times the Sum of the L+R input signals.
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No luck so far. Tons of distortion. I wonder if it's because I'm using a different power supply than what my amp is running off of. I'm lazy and haven't built a step down voltage using the lm317 from my amps power supply...
Have you measured the signals?
For an output of 4times the input you may be severely clipping the signal !!!!
Check it.
For an output of 4times the input you may be severely clipping the signal !!!!
Check it.
Make sure that your common Ground between the Two supply's are connect together as well.
Also you should have a DC blocking capacitor on the output of the filter or at least on the input to the amplifier.
If you can, A full schematic of what you have so far would help us a lot as well.
jer 🙂
Also you should have a DC blocking capacitor on the output of the filter or at least on the input to the amplifier.
If you can, A full schematic of what you have so far would help us a lot as well.
jer 🙂
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Here's what I'm using for the lm3886 and I'm using all of the optional components, this schematic has a few things mine doesn't though-such as the 22uf input cap, and my Rm value is 10k.
For the op-amp, I'm using the basic mixer circuit you guys posted, but I don't know what R values I'm supposed to use so I'm just plugging some in.
But I'm using a separate power supply for the op-amp. I've played around with the ground, I plugged the audio ground into the amp ground, but still had the other supply for the op-amp ground.
For the op-amp, I'm using the basic mixer circuit you guys posted, but I don't know what R values I'm supposed to use so I'm just plugging some in.
But I'm using a separate power supply for the op-amp. I've played around with the ground, I plugged the audio ground into the amp ground, but still had the other supply for the op-amp ground.
Hi chasebank,
I believe that the LM3886 was damaged when you connected mute (pin 8) directly to the negative supply rail, you will need to replace it if that is the case.
Mike
I believe that the LM3886 was damaged when you connected mute (pin 8) directly to the negative supply rail, you will need to replace it if that is the case.
Mike
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