I'm looking at building an amplifier from Class D modules (ICEpower). I am using balanced XLR cables everywhere in my system, so would like to build this amp with XLR input, even if the amp is not designed for balanced input.
How much of a problem is this? I thought I should be able to connect the ground pin to the chassis ground, and add a resistor between the XLR and the amp input? Or is there more to it? Or a potentiometer? I don't the correct value at the moment.
How much of a problem is this? I thought I should be able to connect the ground pin to the chassis ground, and add a resistor between the XLR and the amp input? Or is there more to it? Or a potentiometer? I don't the correct value at the moment.
To convert a balanced signal to an unbalanced input.
You either have a conversion module with op amp, or go through signal conversion transformers.
https://www.audiophonics.fr/fr/modu...ce-desymetriseur-ssm2141-ne5534p-p-14306.html
Or for example: https://www.tlsafrance.fr/promotion...ormateur-audio-di-101-pour-signaux-micro.html
Connecting the cold point to ground is not the best option!
You either have a conversion module with op amp, or go through signal conversion transformers.
https://www.audiophonics.fr/fr/modu...ce-desymetriseur-ssm2141-ne5534p-p-14306.html
Or for example: https://www.tlsafrance.fr/promotion...ormateur-audio-di-101-pour-signaux-micro.html
Connecting the cold point to ground is not the best option!
Just use the + pin on the XLRs. +R and +L with Gnd make a 3 wire single ended input, the source does not care.
I would not leave Pin 3 un-terminated in your XLR input connector. Put a resistor from Pin 3 to ground with the same value as the input resistance of your Class D modules.
Not absolutely necessary, but with this configuration both sides of your balanced interface see the same resistance at the load end.
As mentioned, a transformer scheme or dedicated circuit would be preferable though.
Dave.
Not absolutely necessary, but with this configuration both sides of your balanced interface see the same resistance at the load end.
As mentioned, a transformer scheme or dedicated circuit would be preferable though.
Dave.
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Thanks! A conversion module would be just fine.
And a related question:
When comparing a balanced and un-balanced amplifier, is the amplifier itself designed differently once you get beyond the input section? In other words, is integrating this input module into the amplifier input section the difference between an amp with balanced input and un-balanced input?
I assume they are essentially the same, but I'm not an electrical engineer! I just remember hearing Emotiva discussing their DR amp, describing it as having balanced circuitry going through the amplifier, instead of just having a balanced connection between each component.
I'm not an electrical engineer, but this does not look like a balanced input to me? This is from the data sheet of one of the ICEpower ASX series amps. I was told by someone who I believe to be an electrical engineer, that these amps are not balanced. And I see no indication that they are balanced.
To corroborate, in the amplifier's manual, they show a diagram of the configuration they used when certifying the module, and they showed 2 wire inputs, not balanced inputs.
Is "single ended input" electrical engineer for un-balanced? The ICEpower manual describes the inputs as single ended, and I didn't know if that meant what I thought it meant...
@fredygump Not sure about engineer speak! It is just plain audio terminology really. Yes it means un-balanced.
A balanced (or differential) circuit is essentially two Single ended circuits in a double push/pull configuration, I am suggesting you use one pos signal from each side as the signal line and together with ground wire will make a combined single circuit the other side.
I believe the whole balanced topology was meant for professional equipment and stability over very long cable runs.
I see above you have doubts these are balanced anyway? mamocel suggests they are only balanced in bridged mode. Looking at the chart you posted he is probably right.
I have no experience with ICE class D sorry , but the single ended principle holds true for normal balanced sources. I doubt anything will blow up if you tried an experiment by sending left/right signals and Gnd to a dual channel (single ended) potentiometer
A balanced (or differential) circuit is essentially two Single ended circuits in a double push/pull configuration, I am suggesting you use one pos signal from each side as the signal line and together with ground wire will make a combined single circuit the other side.
I believe the whole balanced topology was meant for professional equipment and stability over very long cable runs.
I see above you have doubts these are balanced anyway? mamocel suggests they are only balanced in bridged mode. Looking at the chart you posted he is probably right.
I have no experience with ICE class D sorry , but the single ended principle holds true for normal balanced sources. I doubt anything will blow up if you tried an experiment by sending left/right signals and Gnd to a dual channel (single ended) potentiometer
It appears to me that this series of amps has un-balanced inputs in all configurations. I would want to see it stated in a manual or data sheet somewhere if someone says otherwise.
Unless someone can prove otherwise, I don't believe any audio equipment with balanced inputs/ outputs actually has differential circuitry inside, except the Emotiva, or possibly high end lab equipment. There may be examples, but I think it is pretty rare.
So the thought is that it doesn't make a difference if the balanced input signal is converted to single ended on the amplifier module itself, or if it is converted on a separate circuit immediately before the amplifier module.
I just want to use balanced XLR cables on all of my equipment, mostly because I like them....
Go ahead and use them Fred, the cables don't care what type of signal they carry, they are proper audio connectors after all. RCAs are not actually designed for audio, they are DC coupling connectors, for lights etc. The Japanese introduced them around the 70s.
One single 3 pin XLR can carry both single ended channel signals, instead of two RCAs, it's a very neat way of doing it. Or you don't have to use all the pins.
It's your project, wire them how you want pal 😉
One single 3 pin XLR can carry both single ended channel signals, instead of two RCAs, it's a very neat way of doing it. Or you don't have to use all the pins.
It's your project, wire them how you want pal 😉
Yup, XLR (or 1/4" TRS) can be stereo or balanced mono. I've never actually seen anyone use XLR as stereo, though.
Ethan Winer told me that RCA connectors were originally used in early TVs to make servicing easier. Wikipedia says they were first used in phonographs, back in the late 1930s. The were designed to be used for internal connections. I guess the later introduction coincided with the introduction of component systems? I'm not sure when that started.
But for wiring, I'll wire the amp input the same as my processor output. It works best that way!
Datasheet
That corporation https://www.thatcorp.com/datashts/THAT_1200-Series_Datasheet.pdf
That corporation https://www.thatcorp.com/datashts/THAT_1200-Series_Datasheet.pdf
Attachments
Hands up!!
I built an adapter cable from a 1/8 TRS to dual RCA cable.. simply cut it in half and added XLR male and female connectors to facilitate extending it to any length with a standard XLR cable. This gets used to connect a remote laptop to a sound system at wedding events, that laptop feeds video to a projector and is usually some distance away from the mix position. In this cable pin 3 of the XLRs is unused and not grounded and in most cases this link is completely noisless, if some noise is picked up I insert a transformer isolator in the link.
I have also used simple balanced to unbalancd cables to connect consumer and pro gear without issue, leaving pin3 open and ungrounded on the balanced end is actually the safest method for the equipment.. some gear can be damaged by grounding an input leg so best to try that first, if it's noise free there is no need to do anything further.
I am convinced that with this ease of wiring, you will lose quality...
A symmetrical signal is not referenced to the ground...The amplitude is between the + and the -...
You will divide the amplitude of the signal in 2 or 1.414... if you reference it to the ground.
This simply creates a virtual mass...
That would be far too easy....Why does he bother making high precision desymetrizers? 🙄
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