I have an old tombstone philco radio cabnet that I want to put a pair of small 4 inch speakers in and a modern amp that I can plug my turntable and or phone into. I want to use the 4 existing knob holes for the amp pots or switch or light or something. I have never done a project like this so I am having trouble figuring out what parts I need to buy. So I was hoping you folks could point me in the right dirrection for components.
I was looking at chip boards but I am worried the potentiomiters wont match the holes in the cabnet. So I thought Id get new pots and run wires to the board, but how do you know what pots to buy? Or which chip for that matter. Im really new to this.
I was also thinking about getting one of those Lepai la-2020a amps and taking it out of the case and putting wire extentions on the pots to match the holes in the radio cabnet. Would that work?
Has anyone done a project like this before that can help point me in the right dirrection to get started. Where to learn the basics and what parts to get. Thank you much!
I was looking at chip boards but I am worried the potentiomiters wont match the holes in the cabnet. So I thought Id get new pots and run wires to the board, but how do you know what pots to buy? Or which chip for that matter. Im really new to this.
I was also thinking about getting one of those Lepai la-2020a amps and taking it out of the case and putting wire extentions on the pots to match the holes in the radio cabnet. Would that work?
Has anyone done a project like this before that can help point me in the right dirrection to get started. Where to learn the basics and what parts to get. Thank you much!
First you disclose what country you are in, so vendor recommendations can be specific. Crossing a border or ocean can be expensive. Putting a location in your user profile is the best way to communicate this.
Second you pick a driver (speaker), with an impedance and a rated wattage. Two of them double the wattage required and halve the impedance if you hook them in parallel.
Thirdly you pick class D (cheap but requires RF shielding to not howl into everything else within 13m) or class AB amp (requires heat management).
Then you buy a power amp of that wattage. On e-bay or ali-baba this requires knowledge, as many boards available online have rediculous wattages advertised. Many ratings on e-bay the board will only last 3 seconds. Furthermore many boards on line are sold without heat sink, which would be stupid to buy as a newby because buying the heat sink costs an extra freight charge, plus the engineering knowledge required. Plus heat sinks are very expensive except from certain boutique vendors.
Deciding whether you are going to mount the heat sinks out the back, install a grill, or install two grills with a fan in one, is required. Deciding whether you are going to protect inquisitive children from dangerous voltages with wood, fabric or plastic, or not, should inform this choice.
Then you buy a power supply of the voltage and current required for the amp. If you have a fan you need power for that which generally should be separate from the power for the amp to avoid electrical noise in the amp.
Then with a DVM, you measure the volume pot taken out of the board with a soldering iron. Warning solder splashes use safety glasses.
Then you buy a pot or two pots (two amps) or a stereo pot (two amps) of that value with a shaft size that will fit the hole in the chassis. You may want one with the power switch on the pot.
Then you wire up the pot, speaker, and power supplies.
Don't forget the fuse holder or circuit breaker, the on-off switch, and the AC cord and strain relief, the wire for internal signals. Buying each individually runs up the freight bill. If your using line level input, as a computer, MP3 player, or radio, you need to buy RCA or 1/4" or 1/8" phone receptacle. (North Am only dimensions)
If you're using a turntable, you need a RIAA preamp board probably with its own separate power supply. Or a special USB turntable, plus the appropriate connector, plus the computer to listen to it. Or use a turntable with line level preamp built in.
If you use more than one input, you need a selector switch or board, plus more RCA or 1/4 phone receptacles. Plus more wire.
Disassembling and rehousing a Class AB amp may be possible but you still have to manage the heat. Disassembling and rehousing a class D amp may annoy all the neighbors as their appliances receive the interferance and behave inappropriately. You can built your own RF screening in the old wood case, but this requires knowledge and parts (screen). Warning, even class AB amps may be subject to RF interferance from nearby transmitters, appliances, or lighting. Screening works going in, also. Plus RF blocks are required on AC and line level or RIAA inputs.
Have fun.
Second you pick a driver (speaker), with an impedance and a rated wattage. Two of them double the wattage required and halve the impedance if you hook them in parallel.
Thirdly you pick class D (cheap but requires RF shielding to not howl into everything else within 13m) or class AB amp (requires heat management).
Then you buy a power amp of that wattage. On e-bay or ali-baba this requires knowledge, as many boards available online have rediculous wattages advertised. Many ratings on e-bay the board will only last 3 seconds. Furthermore many boards on line are sold without heat sink, which would be stupid to buy as a newby because buying the heat sink costs an extra freight charge, plus the engineering knowledge required. Plus heat sinks are very expensive except from certain boutique vendors.
Deciding whether you are going to mount the heat sinks out the back, install a grill, or install two grills with a fan in one, is required. Deciding whether you are going to protect inquisitive children from dangerous voltages with wood, fabric or plastic, or not, should inform this choice.
Then you buy a power supply of the voltage and current required for the amp. If you have a fan you need power for that which generally should be separate from the power for the amp to avoid electrical noise in the amp.
Then with a DVM, you measure the volume pot taken out of the board with a soldering iron. Warning solder splashes use safety glasses.
Then you buy a pot or two pots (two amps) or a stereo pot (two amps) of that value with a shaft size that will fit the hole in the chassis. You may want one with the power switch on the pot.
Then you wire up the pot, speaker, and power supplies.
Don't forget the fuse holder or circuit breaker, the on-off switch, and the AC cord and strain relief, the wire for internal signals. Buying each individually runs up the freight bill. If your using line level input, as a computer, MP3 player, or radio, you need to buy RCA or 1/4" or 1/8" phone receptacle. (North Am only dimensions)
If you're using a turntable, you need a RIAA preamp board probably with its own separate power supply. Or a special USB turntable, plus the appropriate connector, plus the computer to listen to it. Or use a turntable with line level preamp built in.
If you use more than one input, you need a selector switch or board, plus more RCA or 1/4 phone receptacles. Plus more wire.
Disassembling and rehousing a Class AB amp may be possible but you still have to manage the heat. Disassembling and rehousing a class D amp may annoy all the neighbors as their appliances receive the interferance and behave inappropriately. You can built your own RF screening in the old wood case, but this requires knowledge and parts (screen). Warning, even class AB amps may be subject to RF interferance from nearby transmitters, appliances, or lighting. Screening works going in, also. Plus RF blocks are required on AC and line level or RIAA inputs.
Have fun.
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