Hi-Fi operational Amps in OTTAWA
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ddmm
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I have no idea where to buy ICs in Ottawa. I heard that some parts can be ordered in RadioShack but I never try. you could go to radioshack.com to check the location address, or maybe you could order online.
here is a useful site for HIFI DIY
http://www.hifiheaven.com/
you could order parts from the links
but in my opinion, you'd better to buy some modules and assemble them together.It is impossible to get your ideal system in your bedroom.Hi-FI is a matter of industry and manufacture.
here is a useful site for HIFI DIY
http://www.hifiheaven.com/
you could order parts from the links
but in my opinion, you'd better to buy some modules and assemble them together.It is impossible to get your ideal system in your bedroom.Hi-FI is a matter of industry and manufacture.
ddmm
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Hi ddmm,
Thanks for your reply and the website you provided.
Actually, I'm not trying to fool myself with thinking I can beat the commercial product. But things buck me are:
1. My headunit doesn't come with pre-output. Although most power amp(for cars) can take the speaker level input, but the destortion is way way worse than taking the pre-out directly. All I want to do is to extract the pre-out signal and wire it to some sort of pre-amp, the pre-amp will buffer/drive the KENWOOD power amp in the trunk through a 10 feet long audio cord.
2. Since I couldn't find any pre-amp would fit into the little box, I might have to build my own. The second reason is most pre-amp module for home application will take +/-Vcc(dual-power supply), but the car only has a 12V from the battary.
Thanks again!!!
Thanks for your reply and the website you provided.
Actually, I'm not trying to fool myself with thinking I can beat the commercial product. But things buck me are:
1. My headunit doesn't come with pre-output. Although most power amp(for cars) can take the speaker level input, but the destortion is way way worse than taking the pre-out directly. All I want to do is to extract the pre-out signal and wire it to some sort of pre-amp, the pre-amp will buffer/drive the KENWOOD power amp in the trunk through a 10 feet long audio cord.
2. Since I couldn't find any pre-amp would fit into the little box, I might have to build my own. The second reason is most pre-amp module for home application will take +/-Vcc(dual-power supply), but the car only has a 12V from the battary.
Thanks again!!!
ddmm
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first, I'm not car audio fan. I can only talk about this in general.
Although your car deck doesn't have LINE-OUT jack, there must be pre-amp in the box, you can find it and feed it to the power-amp's RCA jack directly, or you could simply turn the sound volumn low, and connect your speaker out to the power amp.
I am not saying you not playing with it. If you have time, you can go ahead to play. You will learn something and have fun.
This is because of the impedance mismatch. Usually the impedance of the LINE-IN input of a power amp is from several hundreds to several K ohm, the output of a "speaker-level" is 1 or 2 or 4 /8/16 ohm. In other words, if the "speaker outout" connects to line-in (like an RCA input), the input is too loud that the power amp "chop" the head and the bottom of the wave form.
Although your car deck doesn't have LINE-OUT jack, there must be pre-amp in the box, you can find it and feed it to the power-amp's RCA jack directly, or you could simply turn the sound volumn low, and connect your speaker out to the power amp.
That is strange config. I am not sure if it is normal in car audio system. Maybe you don't have other choises. The front units and the power unit should be as close as possible, the wires between them should be very short. The "10-feet" signal line is only for connecting speaker and the output of the power amp, because the signal of the power amp is "powerful" enough. The pre-amp output is "way way" too weak, the noise of the 10-foot cord could kill the signal. I don't think you can get satisfied sound with this config.
This is not a problem if you really want play some circuit job. Just change the +/-Vcc to 12V/GND, and add a high speed 10uF cap in each end of your pre amp. The un-balanced 12V/GND give the output of the amplifier a DC bias, a cap can remove this bias to the next module.
I am not saying you not playing with it. If you have time, you can go ahead to play. You will learn something and have fun.
first of all, I have to state I'm not an audio expert, not even a HW guy anymore. 
I did most of my hardware work in Microwave/RF amp,up/down convertor and like before I came to Canada and became a __stupid__ software programmer. 
I really really really miss my soldering iron, Smith-chart, microstrip line, scope, spectrum analyzer... sometimes.
Getting too far off the topic, isn't it?
I know little about Hi-Fi audio in general. Bare with the ignorance I would make here. :blowzy:
Most add-on car power amps have 2 independent input sources - RCA and Speaker-in. The speaker input port has circuit to match the impendence and the power level from the stock power amp inside the headunit. I wouldn't worry too much about that. But I do mind the THD generated by the power amp IC in my headunit.
quote
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The front units and the power unit should be as close as possible, the wires between them should be very short.
___________________________________________________________________
Unfortunately, it's most likely the only option for cars. Nornmally add-on power amps are huge for the dash panel, they won't fit in. Some guys would put it under the seat(especically for truck or van), the glove box or the arm-retainer box. To me, none of those can be my option since my wife wouldn't like to see such a piece of junk (well to her) inside our car, bummer!!!
quote
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The pre-amp output is "way way" too weak, the noise of the 10-foot cord could kill the signal.
___________________________________________________________________
Good point! The high input impedence of the power amp and the length of the cord will be a major contributor to noise. I think I might add a bypass resistor to the RCA input port of the power amp to lower the input impedence if my pre-apm will generate enough output. What do you think?
quote
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This is not a problem if you really want play some circuit job
___________________________________________________________________
I think it is. yes, I could bias the input, but the total voltage is only 12V instead of 24V(+/-12). I think all transitor won't get enough bias current as they are designed(well, yes and no, depends on how good they design their bias circuit).
quote
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If you have time,
___________________________________________________________________
That is the problem!
I did most of my hardware work in Microwave/RF amp,up/down convertor and like before I came to Canada and became a __stupid__ software programmer. I really really really miss my soldering iron, Smith-chart, microstrip line, scope, spectrum analyzer... sometimes. Getting too far off the topic, isn't it?
I know little about Hi-Fi audio in general. Bare with the ignorance I would make here. :blowzy:
Most add-on car power amps have 2 independent input sources - RCA and Speaker-in. The speaker input port has circuit to match the impendence and the power level from the stock power amp inside the headunit. I wouldn't worry too much about that. But I do mind the THD generated by the power amp IC in my headunit.
quote
___________________________________________________________________
The front units and the power unit should be as close as possible, the wires between them should be very short.
___________________________________________________________________
Unfortunately, it's most likely the only option for cars. Nornmally add-on power amps are huge for the dash panel, they won't fit in. Some guys would put it under the seat(especically for truck or van), the glove box or the arm-retainer box. To me, none of those can be my option since my wife wouldn't like to see such a piece of junk (well to her) inside our car, bummer!!!
quote
___________________________________________________________________
The pre-amp output is "way way" too weak, the noise of the 10-foot cord could kill the signal.
___________________________________________________________________
Good point! The high input impedence of the power amp and the length of the cord will be a major contributor to noise. I think I might add a bypass resistor to the RCA input port of the power amp to lower the input impedence if my pre-apm will generate enough output. What do you think?
quote
___________________________________________________________________
This is not a problem if you really want play some circuit job
___________________________________________________________________
I think it is. yes, I could bias the input, but the total voltage is only 12V instead of 24V(+/-12). I think all transitor won't get enough bias current as they are designed(well, yes and no, depends on how good they design their bias circuit).
quote
___________________________________________________________________
If you have time,
___________________________________________________________________
That is the problem!
After searching through my junk box, I found a DSP board in it!!! :
It has a MOTOROLA 56303 24-bit fixed point DSP @ 100Mhz and a dual-channel AD/DA convertor capable of handling 48khz sampling rate at 16-bit Quantization!
I came up with a crazy idea that I would build a digital audio effect processor for my car. Cool, eh?
Here are the couple of things need to be done:
1. This little baby has neither an analog lowpass antialiasing prefilter nor an analog lowpass anti-image postfilter for the AD/DA convertor. I will have to add them on. Again, I need high slew rate Op Amp especially for the anti-image filter.
2. I will pre-define some desired frequency response curves and have our DSP guys figure out how many orders IIR or how many points FIR filter I will need. I am sure they can figure it out with MATLAB within minutes. Then I will consult them the best algorithm to do such digital filtering since there are to many ways to implement the IIR or FIR filter and I don't have enough talent to pick one. If it goes fine, I would do adaptive filtering to generate the best result according to the feedback sound effect inside the car dynamatically. This ain't easy. It deserves a master degree in Digital Signal Processing in Carleton U. Again, I believe our talented DSP guys will give me a hand...:
3. Code my DSP... Ohoo, a software programmer comes into play....
4. The damn DSP board doesn't have EEPROM/EPROM to store the firmware, I will have to add one before it can work on my car.
5. put the board into the spare space under the stock headunit. Since DSP dealing with such a high bit rate stream will generate violent heat, cooling is another damn thing I need to take care of.
6. Wire them up, now I'm ready to go 'thrumb 'thrumb 'thrumb. Hopefully, it won't blow away small items in the trunk and won't kill the birds flying by..... Hehehe....
Thank God I didn't throw away my DSP textbook.
It sounds too good to be true. After all, I might abort my "great project" since it's too complex... Oh well, we'll see.
:It has a MOTOROLA 56303 24-bit fixed point DSP @ 100Mhz and a dual-channel AD/DA convertor capable of handling 48khz sampling rate at 16-bit Quantization!
I came up with a crazy idea that I would build a digital audio effect processor for my car. Cool, eh?
Here are the couple of things need to be done:
1. This little baby has neither an analog lowpass antialiasing prefilter nor an analog lowpass anti-image postfilter for the AD/DA convertor. I will have to add them on. Again, I need high slew rate Op Amp especially for the anti-image filter.
2. I will pre-define some desired frequency response curves and have our DSP guys figure out how many orders IIR or how many points FIR filter I will need. I am sure they can figure it out with MATLAB within minutes. Then I will consult them the best algorithm to do such digital filtering since there are to many ways to implement the IIR or FIR filter and I don't have enough talent to pick one. If it goes fine, I would do adaptive filtering to generate the best result according to the feedback sound effect inside the car dynamatically. This ain't easy. It deserves a master degree in Digital Signal Processing in Carleton U. Again, I believe our talented DSP guys will give me a hand...
:3. Code my DSP... Ohoo, a software programmer comes into play....
4. The damn DSP board doesn't have EEPROM/EPROM to store the firmware, I will have to add one before it can work on my car.
5. put the board into the spare space under the stock headunit. Since DSP dealing with such a high bit rate stream will generate violent heat, cooling is another damn thing I need to take care of.
6. Wire them up, now I'm ready to go 'thrumb 'thrumb 'thrumb. Hopefully, it won't blow away small items in the trunk and won't kill the birds flying by..... Hehehe....
Thank God I didn't throw away my DSP textbook.
It sounds too good to be true. After all, I might abort my "great project" since it's too complex... Oh well, we'll see.
keen_observer
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