Maybe use an ohm meter to determine if the negative speaker terminals are connected to ground first.
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Line Level Converters... any measurements?
- Thread starter mga2009
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You can buy simple dividers (converters) from a variety of places but for myself I usually made H converters to avoid any concern about grounding amplifier outputs. R1 and R2 isolate the output and with R5 form a basic divider. R3 and R4 are optional, and not usually used for audio, except it may be nice to have the adapter be symmetric. I have seen commercial versions of this in the past but have not looked recently.
That's good to know, thanks for the information
That's a good advice, thanks
Thanks, so if I understand correctly I link a resistor on the negative wire, one on the positive then link the two with a third resistor (not including R3 and 4 since optional) then I can avoid any ground trouble with amps? What could you advise to buy on Amazon for example?
Resistors R1 and R2 isolate the power amp's outputs assuming they are high enough in value. Ignoring R3 and R4 (let Rb = 0 ohms) then Vout = Vin * Rc / (2 * Ra + Rc). If you use Ra = 10k resistors for R1 and R2 and Rc = 500 ohms for R5 you'll have about 32.3 dB attenuation (-32.3 dB) or a factor of about 0.024. Then 50 V from your amp (312.5 W into 8 ohms) will provide 1.2 V after the attenuator, and the outputs are isolated by 10 k-ohm resistors to prevent shorting the output. This neglects the input impedance of the load, which will increase the attenuation slightly. You can vary the resistor values for your components.
I have no idea what commercial devices use this, sorry.
No problem for the commercial device, I will make a converter since it seems simple to make. Thanks again for your explanations.
Depends on how much you need to drop, but my guess is 1/4 W will be fine. Remember power P = V^2 / R = I^2 * R so you can calculate the power through the resistors (remember to include plenty of margin). For my example, if you have 50 V (~300 W) across a total divider resistance of 20,500 ohms that is I = V / R = 50 / 20,500 = 2.44 mA. Then using 2.5 mA the power dissipated by each 10k resistor is 0.0625 W and 0.003125 W by the 500-ohm resistor. Even 62.5 mW through the 10k resistors is only 25% of the 250 mW rating so I'd be fine with that -- and most of the time you won't be pushing 300+ W.
Again, you may want to tweak the resistor values for your amplifiers.
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Thanks DonH56, great infos
I know it's an old thread, but it just got linked to/referred to again. In any case, if in doubt, I would add an isolation transformer. Maybe they even exist combined with a stepdown transformer? If not, the connection scheme would be:
speaker out - voltage divider (maybe symmetric, to avoid high voltages relative to ground further down the line) - isolation transformer - equipment that may ground the + or - signal line.
One would have to measure whether the transformer is good enough for the intended measurement (or intended sound quality).
I'm using a setup like this to drive my Evor04 audio visualizer from a (bridge mode chip amp) D class amplifier.
speaker out - voltage divider (maybe symmetric, to avoid high voltages relative to ground further down the line) - isolation transformer - equipment that may ground the + or - signal line.
One would have to measure whether the transformer is good enough for the intended measurement (or intended sound quality).
I'm using a setup like this to drive my Evor04 audio visualizer from a (bridge mode chip amp) D class amplifier.
Line level converters, also known as line output converters or LOCs, are audio devices used to convert a speaker-level audio signal into a line-level signal. This conversion allows you to connect an aftermarket amplifier or audio processor to a factory or OEM (original equipment manufacturer) head unit that doesn't have dedicated line-level outputs.
Line level converters are typically designed to handle different power levels and impedance levels, depending on the specific model and manufacturer. However, as an AI language model, I don't have real-time access to specific product specifications or measurements for individual line level converters.
When choosing a line level converter, there are a few important factors to consider:
Line level converters are typically designed to handle different power levels and impedance levels, depending on the specific model and manufacturer. However, as an AI language model, I don't have real-time access to specific product specifications or measurements for individual line level converters.
When choosing a line level converter, there are a few important factors to consider:
- Power Handling: Line level converters should be able to handle the power output of your car's audio system. Make sure to check the power rating of the converter and ensure it can handle the power level of your speakers or amplifier.
- Input and Output Impedance: Line level converters should match the impedance of your audio system. Impedance mismatches can lead to signal loss or distortion. Consult the specifications of the line level converter and compare them to your audio system's impedance requirements.
- Signal-to-Noise Ratio (SNR): A higher SNR indicates better audio quality. Look for line level converters with a high SNR to ensure clean and clear audio signal conversion.
- Adjustable Output Level: Some line level converters have adjustable output levels, allowing you to fine-tune the output to match the input sensitivity of your aftermarket amplifier or audio processor.
kazsud
Member
These are usually used when adding an aftermarket stereo to a car that has a stock amp.
One should not believe anything an AI says ...
... see below.There is no need for a converter to handle power, just input voltage. Two resistors of suitable resistance are all you need, and 1W power handling is sufficient.
The converters output impedance matters as it should be 10 times lower than the input impedance of the connected input. The converters input impedance should be as high as possible. This guarantes that there is no impedance matchingas this is neither required nor used since 50+ years in audio.
Two resistors have the best possible SNR and are dirt cheap.
This is the only claim which is correct. Replafe one 9f the 2 resistors by a pot and you're done.
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