Hi
When building Computer Speakers that are also powered by the computer,
I was recommended to use Audio Isolation Transformers.
When searaching AliExpress for Audio Isolation Transformers,
some seem to be "600:600", and others are "1300:8".
Examples:
EI14 600:600
5X Audio Transformers 600:600 Ohm Europe 1:1 EI14 Isolation Transformer Ringing B119-in Transformers from Home Improvement on Aliexpress.com | Alibaba Group
EI14 1300:8
10Pcs/Set EI14 Audio Transformer Transformateur Audio 1300 : 8 Ohm POS Isolation Transformador High Frequency-in Transformers from Home Improvement on Aliexpress.com | Alibaba Group
As can be seen, both are called EI14..
What is the difference between 600:600 and 1300:8?
And also, where should I connect the transformer?
Right before the 5v Power Input?
Or before the Audio Inputs?
Thank you
When building Computer Speakers that are also powered by the computer,
I was recommended to use Audio Isolation Transformers.
When searaching AliExpress for Audio Isolation Transformers,
some seem to be "600:600", and others are "1300:8".
Examples:
EI14 600:600
5X Audio Transformers 600:600 Ohm Europe 1:1 EI14 Isolation Transformer Ringing B119-in Transformers from Home Improvement on Aliexpress.com | Alibaba Group
EI14 1300:8
10Pcs/Set EI14 Audio Transformer Transformateur Audio 1300 : 8 Ohm POS Isolation Transformador High Frequency-in Transformers from Home Improvement on Aliexpress.com | Alibaba Group
As can be seen, both are called EI14..
What is the difference between 600:600 and 1300:8?
And also, where should I connect the transformer?
Right before the 5v Power Input?
Or before the Audio Inputs?
Thank you
Last edited:
Jensen Transformers has everything you need to know about audio transformers:
High performance audio transformers and ground isolators.
including a complete book chapter:
AN008 Audio Transformers – Bill Whitlock Chapter 11
High performance audio transformers and ground isolators.
including a complete book chapter:
AN008 Audio Transformers – Bill Whitlock Chapter 11
Use 600:600 transformers, as both the input and the output offer the same impedance (600 ohms).
Put them between the audio out of the computer and the audio in of the computer speakers.
Do NOT put them into the 5V dc power line!
P.S. Isolating transformers are only required if you are experiencing hum on the audio signal, otherwise leave well enough alone.
Put them between the audio out of the computer and the audio in of the computer speakers.
Do NOT put them into the 5V dc power line!
P.S. Isolating transformers are only required if you are experiencing hum on the audio signal, otherwise leave well enough alone.
The 600:600 transformers are isolating transformers, and may be used between a computer headphone output socket and a the input of an active (amplified) speaker system to cut out the hum that sometimes occurs when connecting powered speakers.
The 1300:8 transformers are matching transformers which are used beween a transistor amplifier circuit and an 8 ohm loudspeaker driver. I don't think this is what you are after. If I am wrong, then post more information on your setup.
Perhaps you'd be better off with one of these?
https://cpc.farnell.com/pulse/pls00...5mm-p-s/dp/AV25542?st=ground loop transformer
The 1300:8 transformers are matching transformers which are used beween a transistor amplifier circuit and an 8 ohm loudspeaker driver. I don't think this is what you are after. If I am wrong, then post more information on your setup.
Perhaps you'd be better off with one of these?
https://cpc.farnell.com/pulse/pls00...5mm-p-s/dp/AV25542?st=ground loop transformer
EI-14 is the core size. That determines the power capability vs low frequency response. The rating is for 75 mW at 300 hertz to 3,500 hertz typical. So they should be fine for the much lower power level in your application
The 600/600 ohm one is the right ratio.
The 600/600 ohm one is the right ratio.
Last edited:
Thank you all.
Regarding product Galu linked,
the problem with farnell.com is a crazy shipping cost..
So I will stick with eBay/AliExpress..
BTW,
If I have 2 channels, does it mean I should use 2 transformers?
Regarding product Galu linked,
the problem with farnell.com is a crazy shipping cost..
So I will stick with eBay/AliExpress..
BTW,
If I have 2 channels, does it mean I should use 2 transformers?
Ground loop isolators, like the one from farnel.com, are available from many different suppliers - just search the description. Another example is given below:
JacobsParts AFILTER-B 2-Channel RCA Stereo Ground Loop Isolator: Amazon.com: Industrial & Scientific
This is a stereo (two channel) device. It contains two isolating transformers. You can cut the RCA plugs and sockets off and wire the device directly into your project if required.
To be clear, you need two transformers if you go down the AliExpress path.
Last edited:
Thank you Galu.
I will choose the AliExpress path.
I will choose the AliExpress path.
Do I connect each transformer on the [-] wire or the [+] wire of each channel?
There are several issues with using audio transformers. You would be better off making an amplifier with balanced inputs, so that the power supply ground does not connect to the audio return in your amplifier. That will provide the protection from ground loops that a transformer can, but without the problems and expense of the transformers. Perhaps you intend on tapping into the computer 12V power supply, ie modify your computer? Because the power available from a USB port is limited to 2.5Watts, 5 Watts, or if you are very lucky 10.5 Watts. For great computer sound, I recommend the Klipsch 2.1 system.
Hi steveu
The idea to use one of the PC's 12v plugs is really useful, thank you for it.
OK what does this mean, in terms of my circuit?
How do I make the amplifier's circuit have balanced inputs?
The idea to use one of the PC's 12v plugs is really useful, thank you for it.
Hmm, interesting point.
OK what does this mean, in terms of my circuit?
How do I make the amplifier's circuit have balanced inputs?
The method of connection is shown here:
What Is Ground Loop Isolator? | Electronics Repair And Technology News
Ballanced inputs
The details depend on what parts you use to build your amp. Attached is a example using op-amps, but LT1028 is not a power amp. Many power amp chips do have op-amp style feedback and could drop into this circuit. This circuit is complicated by the use of only positive 12V, since that means you have to divide it into two equal and opposite voltages (+/-6V). If you had a negative voltage available then there would be little or no need for the DC blocking capacitors. Many automotive power amps are bridged to solve that problem but I don't want to complicate this any more. Computers usually do have a negative -12V but rarely will it handle much current.
If you web search "balanced inputs" then you will find lots of articles about the subject. Many of the project in DIYA feature balanced inputs and you can search them as well.
The details depend on what parts you use to build your amp. Attached is a example using op-amps, but LT1028 is not a power amp. Many power amp chips do have op-amp style feedback and could drop into this circuit. This circuit is complicated by the use of only positive 12V, since that means you have to divide it into two equal and opposite voltages (+/-6V). If you had a negative voltage available then there would be little or no need for the DC blocking capacitors. Many automotive power amps are bridged to solve that problem but I don't want to complicate this any more. Computers usually do have a negative -12V but rarely will it handle much current.
If you web search "balanced inputs" then you will find lots of articles about the subject. Many of the project in DIYA feature balanced inputs and you can search them as well.
Attachments
My circuit is actually a ready made amplifier board.
I have several here - they are not circuits that I designed, but simply ones that I purchased.
Most are 5v, PAM chip based.
(so this also means that I cannot really change the circuit, just connect to it before/after it)
I have several here - they are not circuits that I designed, but simply ones that I purchased.
Most are 5v, PAM chip based.
(so this also means that I cannot really change the circuit, just connect to it before/after it)
Best stick to the two 600:600 transformers then. They should work well enough in your application, although better (more expensive ones) are available.
- Status
- Not open for further replies.