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#1
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Newbie question re impedance matching
I'm connecting a small 3" 8 ohm speaker to a low power, battery operated
amplifier that was originally connected to a 4 ohm speaker. I want to match the impedances by making my own small audio transformer using just a torroid ring and some very thin wire from an old AC transformer. Question... What are the mechanics involved. I know I'll need two windings, a primary and then a secondary. Can I just wind some of the wire on one side of the torroid as the primary and then wind 2 times as much (because of 2 times the ohm value) around the other half of the torroid? Is there a minimum number of winds or is it a case of the more winds the better? I'm trying to keep this bedrock simple. Any advice will be appreciated. thanks elfa |
#2
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Newbie question re impedance matching
Elfa,
I want to match the impedances by making my own small audio transformer I'll go out on a limb and say that a home-made transformer will probably have more losses (and other problems) than any efficiency gain you could possibly hope for. This is not to discourage you from experimenting! Go ahead and make the transformer anyway. But don't be disappointed if it doesn't work well. You mentioned having a toroid ring. Audio transformers need to work over a wide range of frequencies. Is your toroid meant for audio, 60 Hz power, or radio frequencies? --Ethan |
#3
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Newbie question re impedance matching
Elfa,
I want to match the impedances by making my own small audio transformer I'll go out on a limb and say that a home-made transformer will probably have more losses (and other problems) than any efficiency gain you could possibly hope for. This is not to discourage you from experimenting! Go ahead and make the transformer anyway. But don't be disappointed if it doesn't work well. You mentioned having a toroid ring. Audio transformers need to work over a wide range of frequencies. Is your toroid meant for audio, 60 Hz power, or radio frequencies? --Ethan |
#4
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Newbie question re impedance matching
In article , Ethan Winer says...
Elfa, I want to match the impedances by making my own small audio transformer I'll go out on a limb and say that a home-made transformer will probably have more losses (and other problems) than any efficiency gain you could possibly hope for. This is not to discourage you from experimenting! Go ahead and make the transformer anyway. But don't be disappointed if it doesn't work well. You mentioned having a toroid ring. Audio transformers need to work over a wide range of frequencies. Is your toroid meant for audio, 60 Hz power, or radio frequencies? --Ethan I have no idea what the toroid was originally designed for....I just bought a handful of them at an electronics discount house. I used one for a balun (used in shortwave antennas for impedence matching cable to plain old copper wire). The toroid is about 1 1/4 inches in diameter. The amp has an 'input' of 450 mV and a max output of 2W. The speaker is 8 ohm and max of 6W. Without impedence matching, my little low power amp over drives the speaker. I just want to reduce the distortion. I'm not an audiophile so I really don't care about the 'perfect' sound system. I have a hearing disability and the whole point of this project is to listen to my small radios (shortwave) with their tiny speakers without the frustration of not understanding what I'm hearing. Now....can you tell me about the number of winds needed? To experiment, I need to start somewhere. thanks elfa |
#5
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Newbie question re impedance matching
In article , Ethan Winer says...
Elfa, I want to match the impedances by making my own small audio transformer I'll go out on a limb and say that a home-made transformer will probably have more losses (and other problems) than any efficiency gain you could possibly hope for. This is not to discourage you from experimenting! Go ahead and make the transformer anyway. But don't be disappointed if it doesn't work well. You mentioned having a toroid ring. Audio transformers need to work over a wide range of frequencies. Is your toroid meant for audio, 60 Hz power, or radio frequencies? --Ethan I have no idea what the toroid was originally designed for....I just bought a handful of them at an electronics discount house. I used one for a balun (used in shortwave antennas for impedence matching cable to plain old copper wire). The toroid is about 1 1/4 inches in diameter. The amp has an 'input' of 450 mV and a max output of 2W. The speaker is 8 ohm and max of 6W. Without impedence matching, my little low power amp over drives the speaker. I just want to reduce the distortion. I'm not an audiophile so I really don't care about the 'perfect' sound system. I have a hearing disability and the whole point of this project is to listen to my small radios (shortwave) with their tiny speakers without the frustration of not understanding what I'm hearing. Now....can you tell me about the number of winds needed? To experiment, I need to start somewhere. thanks elfa |
#6
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Newbie question re impedance matching
Not to discourage you from experimenting either, but my recommendation would
be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless :s "elfa" wrote in message ... I'm connecting a small 3" 8 ohm speaker to a low power, battery operated amplifier that was originally connected to a 4 ohm speaker. I want to match the impedances by making my own small audio transformer using just a torroid ring and some very thin wire from an old AC transformer. Question... What are the mechanics involved. I know I'll need two windings, a primary and then a secondary. Can I just wind some of the wire on one side of the torroid as the primary and then wind 2 times as much (because of 2 times the ohm value) around the other half of the torroid? Is there a minimum number of winds or is it a case of the more winds the better? I'm trying to keep this bedrock simple. Any advice will be appreciated. thanks elfa |
#7
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Newbie question re impedance matching
Not to discourage you from experimenting either, but my recommendation would
be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless :s "elfa" wrote in message ... I'm connecting a small 3" 8 ohm speaker to a low power, battery operated amplifier that was originally connected to a 4 ohm speaker. I want to match the impedances by making my own small audio transformer using just a torroid ring and some very thin wire from an old AC transformer. Question... What are the mechanics involved. I know I'll need two windings, a primary and then a secondary. Can I just wind some of the wire on one side of the torroid as the primary and then wind 2 times as much (because of 2 times the ohm value) around the other half of the torroid? Is there a minimum number of winds or is it a case of the more winds the better? I'm trying to keep this bedrock simple. Any advice will be appreciated. thanks elfa |
#8
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Newbie question re impedance matching
elfa wrote:
Now....can you tell me about the number of winds needed? To experiment, I need to start somewhere. If you feel lucky, you could start with 50 turns for the primary and 70 turns for the secondary. However, I won't guarantee your satisfaction with the result. In my opinion, you should reconsider the suggestions that don't involve an impedance-matching transformer. Have you tried using headphones jacked into your radios, and do they sound OK? |
#9
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Newbie question re impedance matching
elfa wrote:
Now....can you tell me about the number of winds needed? To experiment, I need to start somewhere. If you feel lucky, you could start with 50 turns for the primary and 70 turns for the secondary. However, I won't guarantee your satisfaction with the result. In my opinion, you should reconsider the suggestions that don't involve an impedance-matching transformer. Have you tried using headphones jacked into your radios, and do they sound OK? |
#10
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Newbie question re impedance matching
In article . net, henryf
says... elfa wrote: Now....can you tell me about the number of winds needed? To experiment, I need to start somewhere. If you feel lucky, you could start with 50 turns for the primary and 70 turns for the secondary. However, I won't guarantee your satisfaction with the result. In my opinion, you should reconsider the suggestions that don't involve an impedance-matching transformer. Have you tried using headphones jacked into your radios, and do they sound OK? Thanks for the suggestion re number of turns. As for headphones, that's a 'given'. My challenge is speakers. elfa |
#11
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Newbie question re impedance matching
In article . net, henryf
says... elfa wrote: Now....can you tell me about the number of winds needed? To experiment, I need to start somewhere. If you feel lucky, you could start with 50 turns for the primary and 70 turns for the secondary. However, I won't guarantee your satisfaction with the result. In my opinion, you should reconsider the suggestions that don't involve an impedance-matching transformer. Have you tried using headphones jacked into your radios, and do they sound OK? Thanks for the suggestion re number of turns. As for headphones, that's a 'given'. My challenge is speakers. elfa |
#12
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Newbie question re impedance matching
"Kevin Murray" wrote in message able.rogers.com... Not to discourage you from experimenting either, but my recommendation would be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless. IMHO, still good! This is clearly the best solution. There are lots of cheap 8 ohm speakers around, even free ones - you might find a 4 or 6 inch one - better than your 3 incher. Cheers, Roger ------ Roger Jones, P.Eng. Thornhill, Ontario Canada "Friends don't let friends vote Liberal" (snip) |
#13
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Newbie question re impedance matching
"Kevin Murray" wrote in message able.rogers.com... Not to discourage you from experimenting either, but my recommendation would be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless. IMHO, still good! This is clearly the best solution. There are lots of cheap 8 ohm speakers around, even free ones - you might find a 4 or 6 inch one - better than your 3 incher. Cheers, Roger ------ Roger Jones, P.Eng. Thornhill, Ontario Canada "Friends don't let friends vote Liberal" (snip) |
#14
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Newbie question re impedance matching
Great minds think alike Roger. What industry do you work in?
PS: I'm in Ottawa and I like your politics. "Engineer" wrote in message ... "Kevin Murray" wrote in message able.rogers.com... Not to discourage you from experimenting either, but my recommendation would be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless. IMHO, still good! This is clearly the best solution. There are lots of cheap 8 ohm speakers around, even free ones - you might find a 4 or 6 inch one - better than your 3 incher. Cheers, Roger ------ Roger Jones, P.Eng. Thornhill, Ontario Canada "Friends don't let friends vote Liberal" (snip) |
#15
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Newbie question re impedance matching
Great minds think alike Roger. What industry do you work in?
PS: I'm in Ottawa and I like your politics. "Engineer" wrote in message ... "Kevin Murray" wrote in message able.rogers.com... Not to discourage you from experimenting either, but my recommendation would be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless. IMHO, still good! This is clearly the best solution. There are lots of cheap 8 ohm speakers around, even free ones - you might find a 4 or 6 inch one - better than your 3 incher. Cheers, Roger ------ Roger Jones, P.Eng. Thornhill, Ontario Canada "Friends don't let friends vote Liberal" (snip) |
#16
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Newbie question re impedance matching
In , on 11/19/03
at 02:42 PM, elfa said: ... The amp has an 'input' of 450 mV and a max output of 2W. The speaker is 8 ohm and max of 6W. Without impedence matching, my little low power amp over drives the speaker. I just want to reduce the distortion. I'm not an audiophile so I really don't care about the 'perfect' sound system. I have a hearing disability and the whole point of this project is to listen to my small radios (shortwave) with their tiny speakers without the frustration of not understanding what I'm hearing. [ ... ] Consider rethinking the project. Most amplifiers won't care about your mismatch. Many "8 Ohm" speakers are closer to 6 Ohms anyway. Technically, if your amplifier is optimized for 4 Ohms, you are not driving the speaker as hard as you could. However, why bother? If the speaker is being overdriven now, you don't need to deliver any more power to it. Further thought: Depending on its design, you may be overloading the input stage of your amplifier. You may also be overloading the small radios as you connect them to the amplifier. Because of your hearing disability, you need more acoustic power than that little speaker can provide. Consider finding a larger speaker in a proper enclosure. You may need more power. Also, consider using a tone control or equalizer to taylor the frequency response of your speaker system to compliment your hearing deficiency. --- "WHAT? DON'T SHOUT, I CAN HEAR YOU," has been part of my life for decades. Since I'm a stranger, I'll take the liberty of sharing one of my pet issues. Living with a hard of hearing person can be very frustrating for the rest of us. Often, the hard of hearing person will deny they have a problem. We do catch on after a while and we want learn how to deal with the situation, but the hard of hearing person can sometimes be more helpful. I don't want to drag all my dirty laundry out on this forum, but please be mindful that, what seems like a comfortable listening level to you, could be painfully loud and distracting to nearby normal listeners. (and I do mean physical pain) Having you listen through headphones to your TVs and radios would be much more comfortable for the rest of us, but I know there is a concern that you won't be able to hear or understand what is going on in the room. A better project for you would be to build a TV/radio headphone amplifier that mixes in sound from the room. You could fiddle with the frquency response of the amplifier to heighten your comprehension. I can imagine that features such as separate muting and volume controls for each input would be useful. A plus would be a provision for hearing the phone and doorbell. Some types of hearing loss result in a limited dynamic range. You can't hear quiet sounds, but even moderately loud sounds cause discomfort. There is a very narrow loudness range where your hearing can operate. If this is your situation, consider adding a compressor to your headphone amplifier. ----------------------------------------------------------- SPAM: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, SPAMers are ruining my mailbox] ----------------------------------------------------------- |
#17
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Newbie question re impedance matching
In , on 11/19/03
at 02:42 PM, elfa said: ... The amp has an 'input' of 450 mV and a max output of 2W. The speaker is 8 ohm and max of 6W. Without impedence matching, my little low power amp over drives the speaker. I just want to reduce the distortion. I'm not an audiophile so I really don't care about the 'perfect' sound system. I have a hearing disability and the whole point of this project is to listen to my small radios (shortwave) with their tiny speakers without the frustration of not understanding what I'm hearing. [ ... ] Consider rethinking the project. Most amplifiers won't care about your mismatch. Many "8 Ohm" speakers are closer to 6 Ohms anyway. Technically, if your amplifier is optimized for 4 Ohms, you are not driving the speaker as hard as you could. However, why bother? If the speaker is being overdriven now, you don't need to deliver any more power to it. Further thought: Depending on its design, you may be overloading the input stage of your amplifier. You may also be overloading the small radios as you connect them to the amplifier. Because of your hearing disability, you need more acoustic power than that little speaker can provide. Consider finding a larger speaker in a proper enclosure. You may need more power. Also, consider using a tone control or equalizer to taylor the frequency response of your speaker system to compliment your hearing deficiency. --- "WHAT? DON'T SHOUT, I CAN HEAR YOU," has been part of my life for decades. Since I'm a stranger, I'll take the liberty of sharing one of my pet issues. Living with a hard of hearing person can be very frustrating for the rest of us. Often, the hard of hearing person will deny they have a problem. We do catch on after a while and we want learn how to deal with the situation, but the hard of hearing person can sometimes be more helpful. I don't want to drag all my dirty laundry out on this forum, but please be mindful that, what seems like a comfortable listening level to you, could be painfully loud and distracting to nearby normal listeners. (and I do mean physical pain) Having you listen through headphones to your TVs and radios would be much more comfortable for the rest of us, but I know there is a concern that you won't be able to hear or understand what is going on in the room. A better project for you would be to build a TV/radio headphone amplifier that mixes in sound from the room. You could fiddle with the frquency response of the amplifier to heighten your comprehension. I can imagine that features such as separate muting and volume controls for each input would be useful. A plus would be a provision for hearing the phone and doorbell. Some types of hearing loss result in a limited dynamic range. You can't hear quiet sounds, but even moderately loud sounds cause discomfort. There is a very narrow loudness range where your hearing can operate. If this is your situation, consider adding a compressor to your headphone amplifier. ----------------------------------------------------------- SPAM: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, SPAMers are ruining my mailbox] ----------------------------------------------------------- |
#18
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Newbie question re impedance matching
"Kevin" wrote in message
. rogers.com... Great minds think alike Roger. Ah... thanks, Kevin. What industry do you work in? Engineering - we make process sensors for the steel rolling and mining industries worldwide. Electronics, electro-optics and DSP are the core technologies. PS: I'm in Ottawa and I like your politics. Thanks again. So, how do we get rid of the Li(e)berals? Cheers, Roger "Engineer" wrote in message ... "Kevin Murray" wrote in message able.rogers.com... Not to discourage you from experimenting either, but my recommendation would be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless. IMHO, still good! This is clearly the best solution. There are lots of cheap 8 ohm speakers around, even free ones - you might find a 4 or 6 inch one - better than your 3 incher. Cheers, Roger ------ Roger Jones, P.Eng. Thornhill, Ontario Canada "Friends don't let friends vote Liberal" (snip) |
#19
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Newbie question re impedance matching
"Kevin" wrote in message
. rogers.com... Great minds think alike Roger. Ah... thanks, Kevin. What industry do you work in? Engineering - we make process sensors for the steel rolling and mining industries worldwide. Electronics, electro-optics and DSP are the core technologies. PS: I'm in Ottawa and I like your politics. Thanks again. So, how do we get rid of the Li(e)berals? Cheers, Roger "Engineer" wrote in message ... "Kevin Murray" wrote in message able.rogers.com... Not to discourage you from experimenting either, but my recommendation would be to wire two 8 ohm speakers in parallel and connect them across the output of your amp. This would allow you to reach your amp's full output and also increase your volume ouput. Of course if you don't have a second speaker then my advice is useless. IMHO, still good! This is clearly the best solution. There are lots of cheap 8 ohm speakers around, even free ones - you might find a 4 or 6 inch one - better than your 3 incher. Cheers, Roger ------ Roger Jones, P.Eng. Thornhill, Ontario Canada "Friends don't let friends vote Liberal" (snip) |
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