Hi all!
It's my first timing posting here and would love some help/advice/guidance to get started.
Things started a few days ago when a friend of mine gave me his old LG 5.1 speakers. The DVD/amplifier broke and the speakers were sitting in his house for some months, and they are now mine. He doesn't have the DVD/amp anymore.
Now that I have the speakers and sub, I would love to put them to work in my living room, but I'd also love to assemble the amp on my own as a first project. I've searched a bit but have not found much info on how to build a 5.1 amp. besides some tutorials that are lacking some information.
This is a reference project that I liked, but I'd love to have some more input options, such as an optical one to use in my TV.
Here are the amp and speaker settings from the manual.
Thanks in advance
It's my first timing posting here and would love some help/advice/guidance to get started.
Things started a few days ago when a friend of mine gave me his old LG 5.1 speakers. The DVD/amplifier broke and the speakers were sitting in his house for some months, and they are now mine. He doesn't have the DVD/amp anymore.
Now that I have the speakers and sub, I would love to put them to work in my living room, but I'd also love to assemble the amp on my own as a first project. I've searched a bit but have not found much info on how to build a 5.1 amp. besides some tutorials that are lacking some information.
This is a reference project that I liked, but I'd love to have some more input options, such as an optical one to use in my TV.
Here are the amp and speaker settings from the manual.
Thanks in advance
Attachments
Some things can only be done by IC. For example, demodulating the light signal for 5.1. The best place to start such a project is the broken theater sound unit. It is not the demod IC that blows up, or even the photodetector arrangement that accepts the signal from the TV. What blows up is the outputs or power supply. The outputs due to inadequate heat sink, or shorted speaker wires. The power supply fails due to overage electrolytic capacitors, overstressed switcher components, or hammered protection components. I have had the plastic socket for the fiber optic cable break. I had to throw that stereo detector away and buy another.
You can easily upgrade the output section of such a box with any number of SS amplifier projects. You can replace the audio power supply with something not designed to fail in 3 years (as consumer products usually are). But the front end, you need the IC, fiber optic socket , pcb. Probably surface mount so no alternate mounting method is available.
Pick up the broken set from your friend, or another from a scrap dealer. Then build 5 channels of amp. IC amps are okay in the 70 w class, and with enough heatsink they won't blow up tomorrow. With enough transformer or switcher supply, the 5 channels might actually put out 4x70 w (280) + a real 150 W sub. If the switcher supply has failed, newbies generally cannot repair them. Also the front end of a switcher supply is very dangerous, bringing uncontrolled 250 VAC far onto the pcb, followed by 200 vdc which is just as dangerous sourced by large capacitors.
Frankly, I find 2 channels entirely adequate. You would have to mix down the other 3 channels to 2 or 2+sub to enjoy a program encoded that way. However, most DVD do have a stereo track available. If you finish that and it works, you'll have learned a lot. The stereo TOSlink out of a TV can be demodulated to RCA jacks by a 10 Euro product available from ebay or amazon.
To get started you will need a scope or an AC detector like an analog VOM with DC scales and 250 vac, 100 vac 20 vac & 2 vac scale. You use DC scales to prove the power supply is putting out , and the 2 vac can find the soundtrack coming out on the board. You wil need some q-balls or grabbers to probe the board without shorting traces, or a scope probe. Connect the negative of the meter to analog ground with an alligator clip lead. Frankly DC readings are best done with a DVM as they can be negative. How inexpensive DVM produce random numbers on AC music, and the expensive RMS DVMs completely ignore any frequency over 7000 hz. Never use 2 hands to probe a product with the power on, 25 v across your heart can stop it. Wear no jewelry on hands wrists or neck, 1 v at high amperage through a ring can burn your flesh to charcoal. Wear safety glasses, parts can explode and solder splashes.
You can easily upgrade the output section of such a box with any number of SS amplifier projects. You can replace the audio power supply with something not designed to fail in 3 years (as consumer products usually are). But the front end, you need the IC, fiber optic socket , pcb. Probably surface mount so no alternate mounting method is available.
Pick up the broken set from your friend, or another from a scrap dealer. Then build 5 channels of amp. IC amps are okay in the 70 w class, and with enough heatsink they won't blow up tomorrow. With enough transformer or switcher supply, the 5 channels might actually put out 4x70 w (280) + a real 150 W sub. If the switcher supply has failed, newbies generally cannot repair them. Also the front end of a switcher supply is very dangerous, bringing uncontrolled 250 VAC far onto the pcb, followed by 200 vdc which is just as dangerous sourced by large capacitors.
Frankly, I find 2 channels entirely adequate. You would have to mix down the other 3 channels to 2 or 2+sub to enjoy a program encoded that way. However, most DVD do have a stereo track available. If you finish that and it works, you'll have learned a lot. The stereo TOSlink out of a TV can be demodulated to RCA jacks by a 10 Euro product available from ebay or amazon.
To get started you will need a scope or an AC detector like an analog VOM with DC scales and 250 vac, 100 vac 20 vac & 2 vac scale. You use DC scales to prove the power supply is putting out , and the 2 vac can find the soundtrack coming out on the board. You wil need some q-balls or grabbers to probe the board without shorting traces, or a scope probe. Connect the negative of the meter to analog ground with an alligator clip lead. Frankly DC readings are best done with a DVM as they can be negative. How inexpensive DVM produce random numbers on AC music, and the expensive RMS DVMs completely ignore any frequency over 7000 hz. Never use 2 hands to probe a product with the power on, 25 v across your heart can stop it. Wear no jewelry on hands wrists or neck, 1 v at high amperage through a ring can burn your flesh to charcoal. Wear safety glasses, parts can explode and solder splashes.
Last edited:
thanks a lot for all you guidance @indianajo - but as a first project, I was thinking more in assembling than building one from scratch, for both safety, and start gathering more knowledge in the field.
More something like assembling a few TPA3116D2 2.1 (or any other recommended model) together to have a 5.1 outcome.
More something like assembling a few TPA3116D2 2.1 (or any other recommended model) together to have a 5.1 outcome.
You need to drive the 5 TPA3116d2 class D amp IC's with 5 signals. What are going to use, the earphone jacks of 3 portable FM radios? That is front left stereo 3 times and front right stereo twice. No back channel stereo information and no sub.
To do home theater you have to use a 5.1 decoder IC. Preceded by a TOSlink optical converter. Since the home theater industry has been 100% in the orient, you probably can't even get a datasheet in english for the decoder IC. Much less buy a single IC on an evaluation pcb. The only way for an amateur to get the decoder IC is a dead home theater appliance, which probably has a blown switcher power supply or blown output channels.
As an electronic repair hobbiest for 65 years I have repaired 5 switcher power supplies. I do not suggest a newbie start by trying to accomplish that feat. Very dangerous circuits. Make your newbie mistakes on something simple like a transistor car radio or something. No IC's, no surface mount parts.
I tried to repair a LG flat screen television that lost contact between the photocell that picked up the remote light pulse and the control IC. I could trace the signal throught the wires onto the master PCB. The pcb was multilayer so I could not visually or with a DVM track the signal across the board to any destination. To get the pin # I tried looking up some of the IC's on the internet, specifially datasheetcatalog.com . The remote signal must go to some pin on an IC. LG apparently had not released datasheets on any of the IC's. They don't want to sell IC's, they want to sell appliances. I did manage to find a replacement PCB from a scrapper on ebay that bought old TV's with broken screens. Worked. +1
To do home theater you have to use a 5.1 decoder IC. Preceded by a TOSlink optical converter. Since the home theater industry has been 100% in the orient, you probably can't even get a datasheet in english for the decoder IC. Much less buy a single IC on an evaluation pcb. The only way for an amateur to get the decoder IC is a dead home theater appliance, which probably has a blown switcher power supply or blown output channels.
As an electronic repair hobbiest for 65 years I have repaired 5 switcher power supplies. I do not suggest a newbie start by trying to accomplish that feat. Very dangerous circuits. Make your newbie mistakes on something simple like a transistor car radio or something. No IC's, no surface mount parts.
I tried to repair a LG flat screen television that lost contact between the photocell that picked up the remote light pulse and the control IC. I could trace the signal throught the wires onto the master PCB. The pcb was multilayer so I could not visually or with a DVM track the signal across the board to any destination. To get the pin # I tried looking up some of the IC's on the internet, specifially datasheetcatalog.com . The remote signal must go to some pin on an IC. LG apparently had not released datasheets on any of the IC's. They don't want to sell IC's, they want to sell appliances. I did manage to find a replacement PCB from a scrapper on ebay that bought old TV's with broken screens. Worked. +1
Last edited:
As Indianajo says, the biggest issue is decoding the audio for a 5.1 system. Dedicated home theater preamps are huge dollars usually ( considerably more than a home theater amplifier). Another option is a 5.1 soundcard with a PC but this can get tricky with ground loops unless you can go with optical signals.
If you want to go with a class D chip amp there are lots of TDA7498E prebuilt modules available through the usual places. If you want something that actually sounds good a nice class AB amp would be a good choice, but if you are just going to use it for booming and banging in a home theater you won't hear the difference.
If you want to go with a class D chip amp there are lots of TDA7498E prebuilt modules available through the usual places. If you want something that actually sounds good a nice class AB amp would be a good choice, but if you are just going to use it for booming and banging in a home theater you won't hear the difference.
Thanks a lot @indianajo , I will go the simpler way for sure.
@jwilhelm I actually could use optical signal since most TVs in europe have a deditaced optical output for audio.
I have also thought on making it a more simple 2.1 as a first project and would already bring a nice sound, def. better than the TV one
@jwilhelm I actually could use optical signal since most TVs in europe have a deditaced optical output for audio.
I have also thought on making it a more simple 2.1 as a first project and would already bring a nice sound, def. better than the TV one
A TOSlink to stereo RCA jack line level converter is about $15 on ebay or amazon. I use one of these to supplement the vile sound of my Samsung 32" TV. I have a Peavey PA warehouse mixer amp, and a speaker salvaged from a dead CD player at a charity resale shop. Much better sound. I still watch the news using the internal TV speaker, which is okay for talking.