Building Audio System, Have Questions About ICs? Answered
So as the title states I want to design an audio system, I purchased an old shortwave radio someone gutted, but the case is in great shape and looks really cool, would make a killer looking amp. So a little background, I want to make a stereo amp I can hook up several inputs to and my speakers; likely a turntable, iPod, radio, and whatever else I feel like. The radio came with a nice little 5 position rotary switch for that. The main problem I am facing is what ICs I want to use, and what order. I have not dealt much with audio and at first I thought of buying a radio and just putting the guts into this unit, but I thought this would be a good project to dive into audio work. You can't learn if you don't push your bounds a bit, am I right?
The first IC question is about chips like the PT2322. There are several I have looked at that use a microcontroller for control, and I am not against using an Arduino Micro in this unit, but I am unsure of how the acknowledgment bit works. The data input seems to just be a shift register, data gets clocked in, then latched. Data is fed in in 8 bit strings, but then it mentions an acknowledgement bit as a 9th bit. Is this bit for the latch, or is there a 9th bit fed in before everything is latched? Should it be hi or lo? As well I was looking at the commands, several commands have 7 of their 8 bits written as a *, does this mean that those bits can be set hi or lo? I am sure these aren't difficult questions and I glossed over something important in one of the many data sheets, and that I do not use these chips with any regularity, if ever, doesn't help either! But I like that these ICs all seem to have a 3 band tone control and volume control built into them.
If I were not to use an IC controlled by a microcontroller, I am looking at using a BA3812 for the tone controls, 5 band is a little more then I need, I really only wanted 3, not 2 but not more then 3. Bass, treble and mid range. But I could not find a 3 band IC without microcontroller inputs required for operation, and it was not for the lack of trying. I can handle 5 bands though, however I am wondering, should I go preamp to equalizer to the main amp, or where would I wire in the BA3812? This seems like a stupid question to me, I feel like an audiophile is going to come along and say, "You never put the equalizer after the preamp, it always goes here or there!" or something along those lines. As well, regardless of where its going to get wired in, since I am doing stereo not mono, I assume I will need 2 BA3812's, but the datasheet supplies a circuit for 3 Chips as well. Which would be suggested, 2 or 3? I am wanting to control both left and right tone controls together, so using 5 pots instead of 10, and would also like to be able to have a balance control. I didn't see anything about balance control in the BA3812 datasheet, would there be a good way of accomplishing that with these ICs or the use of a couple op amps maybe? I didn't really look into balance, I should have before asking questions.
For the preamp the LM1036 seemed like a good choice. I was reading into preamps, and they seem more important for the turntable then anything else. The way the grooves on a record are cut they boost the high frequencies so they don't fade awayat lower volumes or something like that. Because of that a preamp that boosts bass and cuts treble is useful and improves sound quality when using turntables. Should I use a preamp only for the turntable input or for all inputs? If I adjust the equalizer for records is a preamp necessary or should I use the preamp and set it with trim pots to boost bass and cut treble a little, or should it be fully adjustable as well?
As far as what to use for the final amplification I am at a bit of a loss. A home theater system I have is 1500W and is adequately loud, but the system I have for my turntable right now think is only 250W I believe and it seems louder. Never really understood wattages for "loudness" or output on sound system. I saw an IC (can't remember number, its a TDA though) dual 50W amplifier. Not sure if 50W for each channel would be enough. Advice would be helpful.
As a side note, if I do go the route of a microcontroller, I found this NJW1186 with stereo input and 5.1 surround output which I thought would be cool.
I really appreciate any help.