posted
This question has bugged me for a while. I know that high voltage decks need a low impedance output for best sound (i.e. 5v 55ohms like my Eclipse 5504). What I don't know is why the low impedance is important. Supposedly, the low impedance has a flatter frequency response. I'm looking for a technical answer as to why. Any help?
Jom
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Posts: 17 | From: Virginia Beach, VA USA | Registered: Feb 2000
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posted
The lower the output impedance on the line, the less chance of noise introducing its self onto it. It also means you can "fan" it out to more amplifiers. My old Nakamichi Mobile CD Tuner 1 only have 500Mv of output, at like 1000ohms, but it was VERY good sounding! Output levels have very little, if anything, to do with "flatness" you refer to. They only have to do with the players ability to reject noise to the next downstream component.
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
So why do manufacturers claim benefits for the lower impedance ratings? It seems the answers you gave also pertain to high voltage benefits. Is a 5V 55 ohm output better than a 5V 1000 ohm output? If so, is it only better because a low impedance load better rejects noise?
Jom
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Posts: 17 | From: Virginia Beach, VA USA | Registered: Feb 2000
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posted
If I remember correctly, most amps have a high input impedance, maybe 10K ohms. Correct? So how does the low output impedance (i.e. 55 ohms) from the deck interact with the amp better than a 1000 ohm output impedance?
Jom
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Posts: 17 | From: Virginia Beach, VA USA | Registered: Feb 2000
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posted
Obviously the difference is small with 5v at 50 ohm and 5 volt at 100 or 200 ohm with an amp input impedance of 10 or 20 k. You start adding multiple amps and you can see a difference. Something you will notice, the lower the deck output impedance the less the amp's impedance has an effect on the sound. A 1K output impedance can be pulled down a little with a 10k load and any capacitance characteristics the input section of the amp might color the sound. The lower the decks output impedance the more impervious it is to be effected by the Mac all the way down to Sentrek amp. Noise is more easily overcome by the high voltage, not that impedance has no bearing on this. Sorry for the confusing rant, I'm a little feverish...
'Where there's a will there's a wall' 'Would you like a little SQ with your SPL?'
Posts: 926 | From: Sugarland, Tx | Registered: May 1999
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posted
Well, here's a rough example. Your building a spl vehicle. You have a deck with 5 volt output at 1k ohm. You have amps with 10k ohm input sections that you want to drive...lets say 10 of them. Obviously their 10 paralleled input sections are going to be in the 1 k ohm range. This is going to drop your deck output voltage in half + or - quite a bit. This is because the decks voltage is 5 volt AT 1 k ohm. Often the internal resistance of the preamp output circuitry will dictate a varying output voltage at different impedances. Also under a heavy load a preamp section will be less linear in it's frequency response. So this will also vary with output impedance and a impedance is given to reference this measurement. In other words you may have a 20 to 20k at + or - 1db at 100 ohms and that will get as bad as + or - 3 db at 50 ohm. You got a lot of things to consider.
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