I have salvaged a pair of speakers from an old B&O Tv.
They sound great but the amplifier doesn’t work so i thought about using them with a new one.
The problem is that the crossover is mounted to the old amplifier and appears to be powered by 9v for some reason.
I would like to keep the crossover, to use it for the new amplifier, and it seems that it can just be pulled out.
My question is: would it work if i just supplied the crossover with 9v from a separate power source so i can use it with a new amp? Or would that damage the board? I don’t know why it needs the power.
I have never seen anything like this so if anyone would know something about it the help would be much appreciated.
They sound great but the amplifier doesn’t work so i thought about using them with a new one.
The problem is that the crossover is mounted to the old amplifier and appears to be powered by 9v for some reason.
I would like to keep the crossover, to use it for the new amplifier, and it seems that it can just be pulled out.
My question is: would it work if i just supplied the crossover with 9v from a separate power source so i can use it with a new amp? Or would that damage the board? I don’t know why it needs the power.
I have never seen anything like this so if anyone would know something about it the help would be much appreciated.
Attachments
It sounds like this is an active, bi-amped system. Meaning, you really have 2 channels of amplifiers + an active crossover for each side, so a total of 4 amplifiers.
If you can't keep the amplifier board, you'll have to find a stereo amp per side to drive them.
None of this sounds worthwhile. Far better off just getting a semi-full range 4-5" FaitalPro speaker or equivalent Peerless and be done with it.
But maybe if you can find a $20 / 10W stereo amp from Parts Express or something you could kludge this to work. You could use a pair of 9V batteries, in series, to give you the + and - 9 V required, at least to experiment. Then you have to figure out a more permanent solution.
Best,
E
If you can't keep the amplifier board, you'll have to find a stereo amp per side to drive them.
None of this sounds worthwhile. Far better off just getting a semi-full range 4-5" FaitalPro speaker or equivalent Peerless and be done with it.
But maybe if you can find a $20 / 10W stereo amp from Parts Express or something you could kludge this to work. You could use a pair of 9V batteries, in series, to give you the + and - 9 V required, at least to experiment. Then you have to figure out a more permanent solution.
Best,
E
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Thanks for the quick response eriksquires
Do you think i would be able to power it with a 9v transformer.
Im not so sure about the +9v -9v. Would’t that require a switching power supply?
Do you think i would be able to power it with a 9v transformer.
Im not so sure about the +9v -9v. Would’t that require a switching power supply?
You need 2 nine volt power supplies, one fir the +9, and one for the - 9. A transformer changes voltage but doesn't turn ac into dc or remove ripple. Whether the power supply is switching or not is irrelevant other than its tendency to produce noise may be worse.
Switching supplies are useful ( and used) in automotive - car stereo- where you have only 12V DC available. Or computers, given the reduced ratio of power and weight. Or anywhere else 😕😀
The only possible shop to find such article is a musician's one. They sell mixers with external power supply, and often they have dual polarity outputs.
The "effect boxes" run on one 9 V battery, and they use the "regular" walmart pwer supply, which consists in one 10-20 W transformer, a diode bridge and a capacitor. For dual voltage, you need a center tap in the secondary winding of the tranformer.
Stabilization after rectification & levellement might be welcomed - That's how feedback works well in switching supplies 🙂
The "effect boxes" run on one 9 V battery, and they use the "regular" walmart pwer supply, which consists in one 10-20 W transformer, a diode bridge and a capacitor. For dual voltage, you need a center tap in the secondary winding of the tranformer.
Stabilization after rectification & levellement might be welcomed - That's how feedback works well in switching supplies 🙂
But you might find ridiculous to spend 100 $ in a plastic box
But it's not strange to find walmarts ( enclosed transformers for safety purpose) having multiple windings, like 10-0-10 V and 30 V.
You can get ±9VDC power supplies via DC or AC plug packs. Depends on how many op amps there are in the circuit and the current requirements.
For a single op amp the TLE2426 works well with a 18VDC plug pack to give a dual supply.
For 2 op amps I've found ESP Project 43 works very well with a 18VDC plug pack to give a dual supply and have used it in tone control circuits.
Project 43 - Simple DC Adapter Power Supply
If there are more op amps which I think would be the case, then a regulated 7809, 7909 circuit running from a 12VAC plug pack (rectified as a full-wave voltage-doubler) would be required.
P05-Mini
Do search on ebay for "LM7809-LM7909-9V-dual-voltage-regulator" as there are heaps available. Just need to add a 12VAC plug pack. Like this:
LM7809+LM7909 +-9V dual voltage regulator rectifier bridge power supply moduleJCA | eBay
For reference on virtual ground circuits:
Virtual Ground Circuits
Since it's an active crossover it needs a 4 channel amplifier (or 2x2) and this was mentioned on post #2. The TPA3116D2 would be a economical choice.
The other option is to build a 2-way passive crossover and use a 2 channel amp.
For a single op amp the TLE2426 works well with a 18VDC plug pack to give a dual supply.
For 2 op amps I've found ESP Project 43 works very well with a 18VDC plug pack to give a dual supply and have used it in tone control circuits.
Project 43 - Simple DC Adapter Power Supply
If there are more op amps which I think would be the case, then a regulated 7809, 7909 circuit running from a 12VAC plug pack (rectified as a full-wave voltage-doubler) would be required.
P05-Mini
Do search on ebay for "LM7809-LM7909-9V-dual-voltage-regulator" as there are heaps available. Just need to add a 12VAC plug pack. Like this:
LM7809+LM7909 +-9V dual voltage regulator rectifier bridge power supply moduleJCA | eBay
For reference on virtual ground circuits:
Virtual Ground Circuits
Since it's an active crossover it needs a 4 channel amplifier (or 2x2) and this was mentioned on post #2. The TPA3116D2 would be a economical choice.
The other option is to build a 2-way passive crossover and use a 2 channel amp.
BTW, the set would have the required power supply but it would be embedded with all the other bits and could get nasty to salvage it.
Thanks for the response.
It sounds like getting the crossover to work with a new amp is not that straight forward.
I think I’ll just build a new crossover for the speakers since I have some parts lying around.
I’ll just have to try to get as close to the original as possible. I’m just afraid that there are too many parameters that I can’t replicate.
It sounds like getting the crossover to work with a new amp is not that straight forward.
I think I’ll just build a new crossover for the speakers since I have some parts lying around.
I’ll just have to try to get as close to the original as possible. I’m just afraid that there are too many parameters that I can’t replicate.
Most opamps run fine on +-12 or +-15 Vdc too, if those power supplies are easier to find. Just check if the capacitors on the crossover can handle the higher voltage.
Agree.
I bet that crossover is Op Amp based, in that case most are very happy with +/- 12/15V .
Very easy to get if your new power amps have split supplies.
Please post a picture of the crossover board or at least which and how many Op Amps does it have.
IF you can salvage it, you know it´s already tuned to your speakers.
Find and upload a user manual or spec sheet for the original amplifier/speakers.
I bet that crossover is Op Amp based, in that case most are very happy with +/- 12/15V .
Very easy to get if your new power amps have split supplies.
Please post a picture of the crossover board or at least which and how many Op Amps does it have.
IF you can salvage it, you know it´s already tuned to your speakers.
Find and upload a user manual or spec sheet for the original amplifier/speakers.
Those schematics are not the crossover, one is the 9V power supply, the other is the power amps.
If you really need the +/- 9v, just search on eBay for a LM317/337 kit. Lots to be found.
If you really need the +/- 9v, just search on eBay for a LM317/337 kit. Lots to be found.
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Rereading this from the beginning, I see this as a salvage/recycling project which should be kept very simple and very inexpensive or it simply won´t make (economic) sense.
A couple questions to the OP:
* do you have the original speakers? Do you have the original cabinet or can build/get a simple/cheap one?
* do you have the original power supply? At least the power transformer, you might also cannibalize main filters and rectifier diodes from the TV
* how damaged are the power amps? *maybe* they work, just need the un mute signal or whatever.
* IF you have to build an amp, using the current speakers and power supply which seems to be +/-20V or thereabouts, you may get a couple compatible ready built boards, and, as suggested by rabbitz, build a passive crossover cabinet using your curret speakers.
Which can be as simple as a 2.2uF capacitor in series with tweeter and nothing else.
The idea , again, is to keep it simple, reasonably quick and inexpensive.
If you have to kludge and stack multiple power supplies plus all the assembly and wiring it will soon complicate into more than it´s worth.
And still you must get some kind of chassis and cabinet to house supply and amplifier.
You might take a picture showing all you have today: speakers, boards, supplies, etc.
I found it weird that the board you showed was crude and simple on one side, and very dense and complex SMD on the other ????
I also fear that the TV set used an SMPS to feed everything, if so I´m not sure you can recycle that, unless it´s working flawlessly.
A couple questions to the OP:
* do you have the original speakers? Do you have the original cabinet or can build/get a simple/cheap one?
* do you have the original power supply? At least the power transformer, you might also cannibalize main filters and rectifier diodes from the TV
* how damaged are the power amps? *maybe* they work, just need the un mute signal or whatever.
* IF you have to build an amp, using the current speakers and power supply which seems to be +/-20V or thereabouts, you may get a couple compatible ready built boards, and, as suggested by rabbitz, build a passive crossover cabinet using your curret speakers.
Which can be as simple as a 2.2uF capacitor in series with tweeter and nothing else.
The idea , again, is to keep it simple, reasonably quick and inexpensive.
If you have to kludge and stack multiple power supplies plus all the assembly and wiring it will soon complicate into more than it´s worth.
And still you must get some kind of chassis and cabinet to house supply and amplifier.
You might take a picture showing all you have today: speakers, boards, supplies, etc.
I found it weird that the board you showed was crude and simple on one side, and very dense and complex SMD on the other ????
I also fear that the TV set used an SMPS to feed everything, if so I´m not sure you can recycle that, unless it´s working flawlessly.
Here is a list of what i have:
- Original speaker in the original cabinets
- 2X Crossovers which was attached to the amps
- 2X Amplifiers from the TV
The power supply from the tv was damaged so i only salvaged the parts i could use, the rest of it went to the bin.
I tried making the original amp work with a +/-20v SMPS i had lying around, but when i played music trough it, it sounded very distorted. Therefore i assumed it was damaged.
So what i wanted to do know is attach the original powered crossovers to the original speakers and just put a knew amp on there. The problem is just that i can't get the crossovers to work with a new amp.
That is where i am now. Trying to get the crossovers to work, mostly because i wanted to preserve the original sound. If i can't get it to work, then I'll just build a new passive crossover. The TV was a Beovision avant 32.
What power supply did you use? Some are designed for a constant load and cannot handle audio amplifiers. As there was at least some sound coming through when you tested the amplifiers, the amplifiers might still to be OK.
I would try to use a different power supply, preferably a linear one (transformer, bridge rectifier, electrolytic capacitors), as these always work with audio amplifiers.
I would try to use a different power supply, preferably a linear one (transformer, bridge rectifier, electrolytic capacitors), as these always work with audio amplifiers.
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That's interesting. I don't see any active devices on the crossover board, and the schematic as well (thought it is cut off on the left).
I also can't quite tell what that little black thing is. Is it a buzzer? A thermal cut off of some sort?
It seems like it gets +- 9 V but it doesn't do anything with it. This could be due to the same connectors/amp being used with a variety of crossovers, or the crossover started as fully active, then was altered.
I also can't quite tell what that little black thing is. Is it a buzzer? A thermal cut off of some sort?
It seems like it gets +- 9 V but it doesn't do anything with it. This could be due to the same connectors/amp being used with a variety of crossovers, or the crossover started as fully active, then was altered.
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