ana Posted February 9, 2006 Report Share Posted February 9, 2006 HelloMy project is about 4 channels audio mixer power amplifier and must design/implement in hardware/circuit implementation…My problem is to confirm whether it is a correct circuit that I implement for mixing stage…And after that I want to change the input signal with a microphone and output with a speaker.But, I have a problem to connect them, whether I can directly connect to it or have a some other circuit must be added to my circuit (as attach)I know that I must to implement many stages to this project, but I try to do a mixing and tone control only. Is it quite ok??I hope you can give an answer as soon as possible…your cooperation I’m really appreciate…TQRegards,ANA Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 9, 2006 Report Share Posted February 9, 2006 Hi Ana,Welcome to our forum. ;DI answered your post in our Theory forum before I saw this one. Please keep posts about the same thing in the same thread.Your mixer circuit is fine but I recommend that you use a low-noise, wide bandwidth audio opamp instead of the old, noisy and narrowband 741. I use TL071 single, TL072 dual and TL074 quad low-noise wide bandwidth audio opamps for nearly everything. The 741 can't produce its full output above 9kHz, and sounds above about 5kHz are terribly distorted. The TL series go to 100kHz with about 1/3rd the noise of a 741. Their distortion over the entire audio band is very low.Each microphone input can have its own low-noise preamp, then feed the mixer. The mixer can feed a tone control circuit which feeds the power amp. Quote Link to comment Share on other sites More sharing options...
ana Posted February 20, 2006 Author Report Share Posted February 20, 2006 Hello…Thanks you for your response. I want to show another circuit which am I can apply in my microphone. I not try yet whether it’s function or not but I not understand certain part in the circuit. (1)What’s mean the input with V1, V2, V3, and V4? What’s kind of input we use? (2) Then, at RV7, volume out- is it means a speaker?(3) How I can connect a mic? Like the figure or must also connect to supply? Quote Link to comment Share on other sites More sharing options...
ana Posted February 20, 2006 Author Report Share Posted February 20, 2006 Hello…Thanks you for your response audioguru.. I want to show another circuit which am I can apply in my microphone. I not try yet whether it’s function or not but I not understand certain part in the circuit. (1)What’s mean the input with V1, V2, V3, and V4? What’s kind of input we use? (2) Then, at RV7, volume out- is it means a speaker?(3) How I can connect a mic? Like the figure or must also connect to supply? Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 20, 2006 Report Share Posted February 20, 2006 (1)What’s mean the input with V1, V2, V3, and V4? What’s kind of input we use?Inputs at V1 to V4 don't have much gain by A1 and A3 so the inputs are for line-level sources like MP3 and CD players or a radio's tuner.(2) Then, at RV7, volume out- is it means a speaker?No. An opamp isn't powerful enough to drive a speaker, and a volume control would melt if a speaker was connected to it. This mixer circuit feeds a power amplifier.(3) How I can connect a mic? Like the figure or must also connect to supply?The mic input is for an electret mic It is supposed to be powered by R3 and R4 in the circuit, but the circuit is wrong. R4 should be removed.The circuit has more problems:1) The AC outputs of A1 and A2 are shorted together.2) The non-inverting input of A3 needs a resistor to ground.3) RV1 to RV4 are not isolated from each other. If one or more are turned down, the remaining input is affected. Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 20, 2006 Report Share Posted February 20, 2006 Ane,You are posting the same topic twice! Please continue replying in your 1st thread.I answered you in this topic:http://www.electronics-lab.com/forum/index.php?topic=5711.msg36102;topicseen#msg36102 Quote Link to comment Share on other sites More sharing options...
ana Posted February 23, 2006 Author Report Share Posted February 23, 2006 Sir…1. I still confuse about what I done. So, where I should put a speaker to my project? Is it I need another circuit? Or it impossible to design the whole things from mic to speaker?2. I don’t know whether the speaker is the point or not, but I want check my project whether its function or not when I use a microphone at input. So, you have an idea? 3. Is it correct if I said that mic is also a level input? If it is true, from the figure 2 (preamp.jpg) that I attach to you, how about the function mic (as shown)?4. Can you give the overall picture about audio mixer from the input level to speaker? I need the description in stage of circuit so that easy I understand how it is built up. Let say (as example)level input ...to ....mixer.... to.... tone control.... to... power amp... to ...speaker5. what the different between channel and level input?isn't same?four input channel means four input levels?6. isn't fine the power amp that I find?(as attach) Quote Link to comment Share on other sites More sharing options...
MP Posted February 23, 2006 Report Share Posted February 23, 2006 I answered your post in our Theory forum before I saw this one. Please keep posts about the same thing in the same thread.Actually, I invite multiple posts if the person is not happy with the first reply or wants to see what others will answer. Some members do not frequent all areas and would have missed the post. It gives others a chance to comment.(besides, in my opinion, this is a circuit request and was posted incorrectly in theory)Welcome to the forum, Ana.Are you attending the main campus in Kuala Lumpur or the campus in Sarawak?One of my best vacations was in Kuching. My wife and I loved it.MP Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 23, 2006 Report Share Posted February 23, 2006 1. where I should put a speaker to my project? Is it I need another circuit?The mixer connects to a power amplifier that you have attached in this thread.2. I don’t know whether the speaker is the point or not, but I want check my project whether its function or not when I use a microphone at input. So, you have an idea?You can measure the level of the amplified mic at the output of the preamp and at the output of the mixer. 3. Is it correct if I said that mic is also a level input? If it is true, from the figure 2 (preamp.jpg) that I attach to you, how about the function mic (as shown)?The mic is a low-level signal input. "Level input" doesn't make sense and is not used.4. Can you give the overall picture about audio mixer from the input level to speaker? I need the description in stage of circuit so that easy I understand how it is built up. Let say (as example)level input ...to ....mixer.... to.... tone control.... to... power amp... to ...speakerCorrect.5. what the different between channel and level input?isn't same?four input channel means four input levels?Your circuit has one amplifier and speaker channel and it has 4 or 5 inputs.A channel is a complete amplifier and speaker: Left channel, right channel. front channel, rear channel.An input is from one of the devices that feeds signals to it.6. isn't fine the power amp that I find?(as attach)Fine? It has a low output power. It is simple so has a fairly high distortion. It has its negative feedback at its input, so can't be driven properly from an opamp or a volume control. Quote Link to comment Share on other sites More sharing options...
ana Posted February 25, 2006 Author Report Share Posted February 25, 2006 hello..how about this circuit..isn't funnction as a microphone and speaker?suppose I want to design with a simple circuit so that my project not too big/load Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 25, 2006 Report Share Posted February 25, 2006 hello..how about this circuit..isn't funnction as a microphone and speaker?suppose I want to design with a simple circuit so that my project not too big/loadWhat do you need to know about this circuit? Quote Link to comment Share on other sites More sharing options...
MP Posted February 25, 2006 Report Share Posted February 25, 2006 Ana,The LM386 is a nice little power amp chip. I have attached the data sheet for this chip. Perhaps it will give you more insight. You can also get more amplification out of this chip if needed. See the data sheet.MPLM386.pdf Quote Link to comment Share on other sites More sharing options...
ana Posted March 2, 2006 Author Report Share Posted March 2, 2006 1. From the picture I’ve attached (power amp), can other transistor types used except TIP31A? 2. What’s the problem with my bass control circuit (as attached) because the output for 3dB cutoff frequency that I get with hardware implementation is not same as my calculation? Suppose I get around 750 Hz at 3 dB but in hardware the value is more that; around 8 kHz Quote Link to comment Share on other sites More sharing options...
ante Posted March 2, 2006 Report Share Posted March 2, 2006 Hi ana,BD241 will replace the TIP31. ;) Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 2, 2006 Report Share Posted March 2, 2006 What’s the problem with my bass control circuit (as attached) because the output for 3dB cutoff frequency that I get with hardware implementation is not same as my calculation? Suppose I get around 750 Hz at 3 dB but in hardware the value is more that; around 8 kHzYou didn't attach a circuit with a bass control. Quote Link to comment Share on other sites More sharing options...
ana Posted March 3, 2006 Author Report Share Posted March 3, 2006 hello..i'm not sure whether the picture has done attched or not..so i post a same question n pictureQ: What’s the problem with my bass control circuit (as attached) because the output for 3dB cutoff frequency that I get with hardware implementation is not same as my calculation? Suppose I get around 750 Hz at 3 dB but in hardware the value is more that; around 8 kHz Quote Link to comment Share on other sites More sharing options...
ana Posted March 3, 2006 Author Report Share Posted March 3, 2006 hello.. my mistake..Q: What’s the problem with my bass control circuit (as attached) because the output for 3dB cutoff frequency that I get with hardware implementation is not same as my calculation? Suppose I get around 750 Hz at 3 dB but in hardware the value is more that; around 8 kHz Quote Link to comment Share on other sites More sharing options...
ana Posted March 3, 2006 Author Report Share Posted March 3, 2006 my mistake again..sorry for this errorabout this question-Q: What’s the problem with my bass control circuit (as attached) because the output for 3dB cutoff frequency that I get with hardware implementation is not same as my calculation? Suppose I get around 750 Hz at 3 dB but in hardware the value is more that; around 8 kHz Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 3, 2006 Report Share Posted March 3, 2006 Here is an explanation about your tone control circuit:http://www.ecircuitcenter.com/Circuits/op_tone1/op_tone1.htm Quote Link to comment Share on other sites More sharing options...
ana Posted March 12, 2006 Author Report Share Posted March 12, 2006 hello..i've a quest to ask1) according to the circuit that i attach before(poweramp.gif), what d function of LED on that circuit?2) what is the best or simple word to explain bout audio mixer n equalizer?as i know, mixer is a shaping of sound-other than that, i don't know what to describe clearly bout it..sometimes, i think that nothing special bout my projet cz i juz do for mixer n equalizer only...plz give me a clearly bout that-i nvr seen n know d function of audio mixer Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 12, 2006 Report Share Posted March 12, 2006 1) according to the circuit that i attach before(poweramp.gif), what d function of LED on that circuit?It doesn't have an LED. It has three 1N914 ordinary diodes to avoid crossover distortion.2) what is the best or simple word to explain bout audio mixer n equalizer?as i know, mixer is a shaping of sound-other than that, i don't know what to describe clearly bout it..sometimes, i think that nothing special bout my projet cz i juz do for mixer n equalizer only...plz give me a clearly bout that-i nvr seen n know d function of audio mixerAn audio mixer adds together sound signals from more than one source. Each input has its own level control to allow a proper blend.An audio equalizer adjusts the levels of different audio frequencies. Quote Link to comment Share on other sites More sharing options...
ana Posted March 23, 2006 Author Report Share Posted March 23, 2006 hello..where i can get info about speaker 8ohm,0.25W??or the datasheet?? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 23, 2006 Report Share Posted March 23, 2006 where i can get info about speaker 8ohm,0.25W??or the datasheet??Speakers have power ratings that are measured in Watts, not mW. Their max power rating is the amount of power the speaker can take from an amplifier continuously without damage to itself if it is in a suitable enclosure. A speaker operates fine with less power than its max power rating.Speaker manufacturers list spec's for their good speakers.The LM386 amp circuit you posted gives 250mW to an 8 ohm speaker when it has a 6V supply, and 375mW with a 9V supply. This is a very low amount of power for a speaker, will not sound very loud and only a tiny speaker would be damaged by it. Quote Link to comment Share on other sites More sharing options...
ana Posted March 30, 2006 Author Report Share Posted March 30, 2006 latest one..i use 8ohms, 0.25W for supply 12V...unfortunately, my voice not too clear and more noise occurs..how should i faced with this prob?isn't i must change my speaker-as u said that it will damage the speaker itself-?for ur infomation, i use the own stage for mic, and power amplifier...this prob occur when i combine between stage of mic, mixer, preamp and pwr amp...tone controls not included..isn't has d other way to solve this prob? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 30, 2006 Report Share Posted March 30, 2006 latest one..i use 8ohms, 0.25W for supply 12V...unfortunately, my voice not too clear and more noise occurs..how should i faced with this prob?isn't i must change my speaker-as u said that it will damage the speaker itself-?for ur infomation, i use the own stage for mic, and power amplifier...this prob occur when i combine between stage of mic, mixer, preamp and pwr amp...tone controls not included..isn't has d other way to solve this prob?The noise is probably Acoustical Feedback Howling and Squealing. This is caused when the microphone can hear the speaker's sound and the amplifier amplifies it so the sound goes around and around.Stop the feedback by turning the speaker and microphone in different directions, by separating them, by turning down the volume or by recording your message then playing it back.Your voice is not clear probably because the volume is too high and either the amplifier. speaker or both are clipping. Quote Link to comment Share on other sites More sharing options...
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