Is this an active crossover application? Things won't change much, at least for the woofer. You will still be current-limited.
A better way to use use two chips per channel is the parallel configuration, where each chipamp will effectively 'see' half the load. This means you can push up to the 32-35V supply voltage and run a 4 ohm load. I use 4 chips/channel this way to run 8x 10" subwoofers wired up as 2 ohm loads, and it runs without a hitch.
The caveat is the three resistors for gain and input impedance need to be very tightly matched, or you need to run large ballast resistors to prevent the chips' outputs from feeding each other instead of the load.
Thanks Sangram and Naresh.
@ Naresh
The capacitor issue is resolved I have settled for 4x4700uf per channel 63v caps. Not a branded make but oversized so probably OK. This is my fun learning project.
regards
OK understood.
@ Naresh
The capacitor issue is resolved I have settled for 4x4700uf per channel 63v caps. Not a branded make but oversized so probably OK. This is my fun learning project.
regards
Hi,
please help me with this. I am finishing up this very cheap lm3886 with enclosure and all. Layout details are as shown in picture. The power switch is single 5 A capable so will be common for switching ON two separate power transformer for two channels. My cabinet is metal chassis. My questions are (also shown with color green in pic)
1) Do I need three wire mains AC cable (Live, Neutral, and earth)? or two wire will do (Live and neutral/return) ? as my other equip. are two wire mains cord.
2) If yes, should the mains earth be connected to metal chassis ?
3) Where to connect Power supply 0v reference (After rectification and filteration) ? To metal chassis ? Or should be left floating ?
4) Do I need to connect Signal in and out ground of amplifier module to anything ? It is Chinese XY lm3886 board.
5) Is bulb and fuse connection OK ?
6) For second channel transformer the primary connection of transformer will be tapped after single power swtich and provided separate bulb and fuse. Is that OK ?
thanks very much.
please help me with this. I am finishing up this very cheap lm3886 with enclosure and all. Layout details are as shown in picture. The power switch is single 5 A capable so will be common for switching ON two separate power transformer for two channels. My cabinet is metal chassis. My questions are (also shown with color green in pic)
1) Do I need three wire mains AC cable (Live, Neutral, and earth)? or two wire will do (Live and neutral/return) ? as my other equip. are two wire mains cord.
2) If yes, should the mains earth be connected to metal chassis ?
3) Where to connect Power supply 0v reference (After rectification and filteration) ? To metal chassis ? Or should be left floating ?
4) Do I need to connect Signal in and out ground of amplifier module to anything ? It is Chinese XY lm3886 board.
5) Is bulb and fuse connection OK ?
6) For second channel transformer the primary connection of transformer will be tapped after single power swtich and provided separate bulb and fuse. Is that OK ?
thanks very much.
Attachments
Mains earth needs to connect to chassis. The screw for this should not share any other duty, and any coating on the chassis needs to be scraped off for a good contact. A non-slip washer should be used.
All external protruding metal parts must also be at mains earth. This means RCA sockets of most types and binding posts that do not have insulating collar.
This is achieved by also connecting power supply common/0V to the same mains earth, where you have connected the earth wire from the inlet. In the event of hum a 'hum breaker' may be installed between 0V and mains earth, it allows for a maximum of 700mV between the two and is capable of handling a large enough amount of current to allow the fuse to blow while keeping user safe.
What bulb is this?
All external protruding metal parts must also be at mains earth. This means RCA sockets of most types and binding posts that do not have insulating collar.
This is achieved by also connecting power supply common/0V to the same mains earth, where you have connected the earth wire from the inlet. In the event of hum a 'hum breaker' may be installed between 0V and mains earth, it allows for a maximum of 700mV between the two and is capable of handling a large enough amount of current to allow the fuse to blow while keeping user safe.
What bulb is this?
Thanks Sangram.
My speaker binding posts are totally insulated but Signal Input RCA sockets are not. The bulb I plan to use are neon ones Which comes in DP switches here in India. I also have some chinese power switches with bulb in them. Bulb is just a reminder to turn amplifier off when not in use.
I will connect AC mains Earth Wire to enclosure metal chassis and Power supply 0V reference (On rectifier-Filter board) to different point on same metal chassis. Is that Correct ?
regards.
My speaker binding posts are totally insulated but Signal Input RCA sockets are not. The bulb I plan to use are neon ones Which comes in DP switches here in India. I also have some chinese power switches with bulb in them. Bulb is just a reminder to turn amplifier off when not in use.
I will connect AC mains Earth Wire to enclosure metal chassis and Power supply 0V reference (On rectifier-Filter board) to different point on same metal chassis. Is that Correct ?
regards.
1. That bulb connects in parallel to the mains, not series. It cannot handle the entire load of the amplifier.
Same goes for all power switch illumination.
2. 0V and mains earth have to connect to chassis at practically the same point. You cannot use the chassis to conduct any sort of current, let alone a mains fault current.
OK understood.
Thanks gentlemen. Will implement these things.
Edit : just thought about this. Can I use transformer AC secondary* for neon bulbs. (I will have either 18v or 36v) Reason being the way I will be arranging PS boards the wires to front panel will be short and closer so I can avoid clutter in already my crammed amplifier enclosure.
* Or will that be counter producting of amplifier functioning. I mean any imact of secondary impedance changing etc.
thx.
Thanks gentlemen. Will implement these things.
Edit : just thought about this. Can I use transformer AC secondary* for neon bulbs. (I will have either 18v or 36v) Reason being the way I will be arranging PS boards the wires to front panel will be short and closer so I can avoid clutter in already my crammed amplifier enclosure.
* Or will that be counter producting of amplifier functioning. I mean any imact of secondary impedance changing etc.
thx.
Last edited:
It's actually a bit more complicated than that. You have to deal with the current required to magnetize the transformer core and to charge the reservoir caps. That current can be substantial.
I write quite a bit about it here and show some measurements that I think will interest you: The Ultimate Guide to Soft Start Design – Neurochrome
Tom
Hiten, The neon 'Bulb' is probably 110V. It has a large series resistor and will not operate properly from low voltage. It is designed to connect to the mains and should be powered from there. I would still advocate LEDs because they're more reliable, brighter and efficient than neon.
If you post a photo of what you're trying to use, it would be possible to give you better advice. Front-panel mounted lighting fixtures using inbuilt neons are not a great choice for indication. I thought you talked about it being in the switch, the examples I've seen of these are already connected to the rocker switch and need no further user intervention.
If you post a photo of what you're trying to use, it would be possible to give you better advice. Front-panel mounted lighting fixtures using inbuilt neons are not a great choice for indication. I thought you talked about it being in the switch, the examples I've seen of these are already connected to the rocker switch and need no further user intervention.
Yes I do have some iluminated power switches. But they are filmsy with thin lugs. I have vintage Indian robust tight spring action switch (No light though) which I intend to use. So was thinking of salvaging neon lamps from filmsy switch and use them as indicator.
Will use LEDs as recommended.
But out of curiosity. Will a resistor-Neon bulb on primary have any ill effect on functioning ?
thanks
Will use LEDs as recommended.
But out of curiosity. Will a resistor-Neon bulb on primary have any ill effect on functioning ?
thanks
Thanks for the hint. Goes to show I still haven´t read all of your well researched and well-written page.
It sure is not a trivial subject as one could easily/naively guess.
I have a lot of information available and much of it is pretty dense, so I understand.
Littelfuse has a good app note on the topic as well:
https://www.littelfuse.com/~/media/...ittelfuse_fuseology_application_guide.pdf.pdf
If the link breaks, just search for it by title, "Fuse Characteristics, Terms and Consideration Factors".
Tom
Littelfuse has a good app note on the topic as well:
https://www.littelfuse.com/~/media/...ittelfuse_fuseology_application_guide.pdf.pdf
If the link breaks, just search for it by title, "Fuse Characteristics, Terms and Consideration Factors".
Tom
Hi,
In attached picture
1) Only one channel and Only ground connection in green is shown and other channel will be replicated.
2) My source always will be Mains 2 Pin CD player (No earth connection on it)
I have made front/back panel, drilled the holes in chassis for components, Before I start fixing in component and wiring would like to know
for start ground I will take EXTRA wire from (1) Speaker terminal pin ground (2) Signal input pin ground (3) Amplifier Module Speaker Out ground (4) Power supply board Rectified 0v Ground to the Center point shown in green circle Which will have Mains Earth wire connected to metal chassis. Tell me if this is correct ?
As this is my frugal, learning and getting hands dirty DIY the chassis is small and not much space left. However I have second option (shown in grey) for Star Ground near power supply board. So where would it be better ? Near Back panel where all input and outputs are OR near Power Supply Rectifier Filter Board as shown in OPTION 2
On the Amplifier module (XY Chinese brand). My multimeter shows All the output, input and PS ground as short. So why not take only one PS ground to the chassis Star ground where mains earth wire is ? Do tell if any wire can be eliminated to have less clutter.
Thanks very much
In attached picture
1) Only one channel and Only ground connection in green is shown and other channel will be replicated.
2) My source always will be Mains 2 Pin CD player (No earth connection on it)
I have made front/back panel, drilled the holes in chassis for components, Before I start fixing in component and wiring would like to know
for start ground I will take EXTRA wire from (1) Speaker terminal pin ground (2) Signal input pin ground (3) Amplifier Module Speaker Out ground (4) Power supply board Rectified 0v Ground to the Center point shown in green circle Which will have Mains Earth wire connected to metal chassis. Tell me if this is correct ?
As this is my frugal, learning and getting hands dirty DIY the chassis is small and not much space left. However I have second option (shown in grey) for Star Ground near power supply board. So where would it be better ? Near Back panel where all input and outputs are OR near Power Supply Rectifier Filter Board as shown in OPTION 2
On the Amplifier module (XY Chinese brand). My multimeter shows All the output, input and PS ground as short. So why not take only one PS ground to the chassis Star ground where mains earth wire is ? Do tell if any wire can be eliminated to have less clutter.
Thanks very much
