Hello everyone!
I'm a beginner in the field of audiophilia and I'm taking the first steps to build my first sound system (always according to what my wallet can handle 🤣).
I started with an AB LM3886 50W/8 Ohms amplifier per chip. As I am using two ICs, I will have 100W in total.
Then I bought two used aiwa boxes, they are not in very good condition, but it is the beginning of my adventure, so I think it is ok for that. They are SX-FNV800 model.
My question is:
1 - These speakers are 3-way with front surround, and the information on the back of the box is: Main speaker (6 Ohms) and surround speaker (16 Ohms). Knowing that the box has 4 speakers, how do I find out which wires coming out of the back of the box are from the surround and which are from the main?
2 - Which speakers belong to the main speaker and which ones belong to the surround? (Woofer, Mid-range, tweeter, super tweeter)
3 - To make the connection to any amplifier, even if there is no impedance matching (as in my case), can I ignore the surround?
4 - If I can't ignore the surround, is there a way I can connect them to the main speaker (because I'm limited to 2 channels)?
That's it folks, I'll be following the thread and if you have any questions I'll try to explain it with other words. I hope you understand my situation, one day I will finally get some complete and well-made systems!
I'm a beginner in the field of audiophilia and I'm taking the first steps to build my first sound system (always according to what my wallet can handle 🤣).
I started with an AB LM3886 50W/8 Ohms amplifier per chip. As I am using two ICs, I will have 100W in total.
Then I bought two used aiwa boxes, they are not in very good condition, but it is the beginning of my adventure, so I think it is ok for that. They are SX-FNV800 model.
My question is:
1 - These speakers are 3-way with front surround, and the information on the back of the box is: Main speaker (6 Ohms) and surround speaker (16 Ohms). Knowing that the box has 4 speakers, how do I find out which wires coming out of the back of the box are from the surround and which are from the main?
2 - Which speakers belong to the main speaker and which ones belong to the surround? (Woofer, Mid-range, tweeter, super tweeter)
3 - To make the connection to any amplifier, even if there is no impedance matching (as in my case), can I ignore the surround?
4 - If I can't ignore the surround, is there a way I can connect them to the main speaker (because I'm limited to 2 channels)?
That's it folks, I'll be following the thread and if you have any questions I'll try to explain it with other words. I hope you understand my situation, one day I will finally get some complete and well-made systems!
Attachments
0. I was able to find the manual for that system. You don't have the surround speakers. For some reason the label on your speakers talks about the whole system. Those are the front speakers, and they are 6 ohms. https://www.manualslib.com/manual/3525/Aiwa-Nsx-Av800.html?page=4#manual
1. I believe that is a typical three way speaker. It appears that there is a single pair of wires coming out of it. That connects to the internal crossover and divides the sound between all the speakers in the box. Unless something is broken, that is exactly what you want. Don't mess with it. You don't have the surround speakers. They are two smaller speaker boxes. You can connect a 1.5V battery briefly across the wires and you will see the woofer move and hear a click coming from all the other drivers.
2. That box is the front speaker. The rear speakers are separate and shown in the manual. Forget about those.
3. Yes
4. Connect the pair of speakers you have to your amplifier and enjoy.
Hope that helps. That is just some weird confusing labeling they put on those speakers. That is an excellent amplifier. With a proper power supply it will work very well for you. I have built several of these. I power mine with a pair of small switching power supply boards and they work perfectly. https://www.amazon.com/Switch-Supply-Module-Isolated-Output/dp/B07GWCPTQB As the output of these power supplies are isolated, they can be connected in series to produce the +/- power supply needed for these amplifiers.
1. I believe that is a typical three way speaker. It appears that there is a single pair of wires coming out of it. That connects to the internal crossover and divides the sound between all the speakers in the box. Unless something is broken, that is exactly what you want. Don't mess with it. You don't have the surround speakers. They are two smaller speaker boxes. You can connect a 1.5V battery briefly across the wires and you will see the woofer move and hear a click coming from all the other drivers.
2. That box is the front speaker. The rear speakers are separate and shown in the manual. Forget about those.
3. Yes
4. Connect the pair of speakers you have to your amplifier and enjoy.
Hope that helps. That is just some weird confusing labeling they put on those speakers. That is an excellent amplifier. With a proper power supply it will work very well for you. I have built several of these. I power mine with a pair of small switching power supply boards and they work perfectly. https://www.amazon.com/Switch-Supply-Module-Isolated-Output/dp/B07GWCPTQB As the output of these power supplies are isolated, they can be connected in series to produce the +/- power supply needed for these amplifiers.
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Thank you very much for your answer! It really helped me, a lot!
The only thing that made me think a little bit about it is that there is 2 pairs of wires coming out from each box.
I tried the 1.5V test and i got theese results:
Yellow-black: Turns on the left speaker of the left box; Turns on the right speaker of the right box.
Black-Black w/ white: Turns on the woofer.
With this test, i couldn't hear the super tweeters and the remaining speaker of each box (right speaker of the left box and left speaker of the right box).
Is there any configuration to test those remaining? I know the best way to try them is openning the box and test one by one, but the wood is old and I am scared to break it. Do you think they are broken just by the results of the test with the battery?
That's great. I must have found the wrong manual. They probably made lots of versions of this system, changing it each year.
If there are two sets of wires, your first assumption seems correct. There are both front and "surround" speakers in each box. It is not uncommon for companies to put fake tweeters in this kind of thing. I have a pair of Sony portable speakers with fake tweeters. It is also possible that the tweeter and or midrange are just blown out if you don't hear anything. It is often the case that when speakers are driven too hard, particularly with an amplifier driven to clipping, that the midrange and tweeter can be burned up while the woofers survive. There may be screws somewhere that let you open a speaker like this. Unfortunately modern designs eliminate screws in favor of snap together plastic parts. Screw heads can be hidden under stickers. Gentle prying can reveal the position of hidden screws. If the midrange and tweeter were blown, it sounds like you might be able to use the surround speaker as the midrange. Possibly swapping the position in the box or just connecting to the crossover in place of the midrange.
Got it, friend! Thank you for your reply.
The last question is: If the surround has 16 Ohms and the woofer has 6 Ohms, if I use them in parallel the equivalent impedance would be about 4 Ohms. With this topology, can I use the 2 boxes with my LM3886 showed in the photo? Is this the best arrangement I can get with this PCB?
If you don't open the boxes, I would add a capacitor in series with that surround driver to keep the bass out of it. 4.0 uF would let 2,500 Hz and above go to it. 8.0 uF would let 1.250 Hz and above go to it. The amplifier will drive that just fine. If you aren't going to make measurements, that would probably work. I just used this website to compute the values. https://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/.
Thank you friend! August will be my time to get this done. I'll post the result then.
Bro, can I use just one board (same as you linked)? If the output is isolated, maybe it is possible to connect both channel is series to get +24 -24. I know that this is not the correct voltage as required (+28 -28), but I think it will work fine. What do you think?
You need two of those power supply boards. Each board has a single 24 volt output. The second output is 5 volts, and that isn't useful for the amplifier. So two boards with the 24 volt outputs connected in series does the job. +/- 24 volts is plenty.
Hey Friend, thank you for your help! It worked fine.
Unfortunately I had a problem with my left LM3886. I'm gonna test it in another board with a good osciloscope to see what's happening.
I made a power supply with my 12+12V transformer (2A), +-18Vdc with 2x 22.000uF capacitors. It is not a good voltage, but it was enough to feel the power of those speakers and amplifier.
Thank you for everything!
I hope you are able to figure it out. You can always post pictures of the PCB front and back on here and maybe someone will be able to spot the problem. The PCB you showed looked good, but I can't tell from that angle if everything is in place. If you have too much trouble, or your PCB gets damaged, there are many different circuit boards available for very low prices. Search for "lm3886 pcb" on eBay as the links to follow won't age well. I have built many of these XY boards and they work well. https://www.ebay.com/itm/295163098487 My son is building up one of these dual amplifier boards today. https://www.ebay.com/itm/224585497340.
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I checked the PCB and found nothing. My only device to analyze it is a multimeter. At the afternoons I can use an osciloscope.
I hope I can find the problem too, where I live, the Lm3886 is very expensive nowadays.