n00bular question about output level

**kevin1162** · 02-28-2009, 04:15 AM

Ok still researching...

My initial plan for my carputer was to try and drive my car speakers from the usb soundcard. After some reading (and thinking about it) this is not going to drive the speakers nicely, so i'm going to get an amp.

Now i've never installed an amp before (hence oncoming n00b question), but not really worried about it. What i'm trying to determine is if the soundcards output is low-level or line level? the soundcard in question is a soundblaster extigy.

My understanding is 'line-level' is what a head-unit would feed directly to the speakers, and 'low-level' would be a pre-amp output from the headunit to connect to an amp. I'm probably not looking in the right place but i can't find what voltage level pre-amp level is and what voltage line-level is or output voltage specs for this soundcard.

Thanks

**jessekilner** · 02-28-2009, 07:20 AM

you are correct. line level is typical radio speaker level. I would double check that that particular sound card doesnt lock up on hibernate or standby though, I recall soundblaster threads about that.. not sure models... But if you want to know the cards low level output it would be in the vicinity of 0.3V-0.35V, not sure your amp type but check the model number in google to see what it's Nominal Voltage input range would be on preamps as if it's a lower grade amp the .3v would not be sufficient enough which can cause "whining" or buzzing noise in speakers. I have a Sony and it's min voltage range is .3V I simply turned up the gain to compensate the low voltage and it sounds loud, very loud! no noise..

**WuNgUn** · 02-28-2009, 08:29 AM

Some of the better sound cards use high-voltage line outs...around 3V I think?

**kevin1162** · 02-28-2009, 05:06 PM

i'm aware some of the SB cards have hibernate issues, but i haven't had any yet... And i've been trying to make it fail on purpose going in/out of standby.

The amp i'm considering is either an alpine MRP-F300 or MRP-F600, it has both low level and speaker level inputs. I just don't know whether my soundcard is outputting low level or speaker level signal since i can't find the tech specs on it.

**WuNgUn** · 02-28-2009, 05:13 PM

Low level most definitely!!!!

Speaker level would be already amplified output, i.e. amp to amp...

**kevin1162** · 02-28-2009, 05:27 PM

cool, thanks alot

**Will Albers** · 03-04-2009, 08:01 AM

Originally Posted by jessekilner

you are correct. line level is typical radio speaker level. I would double check that that particular sound card doesnt lock up on hibernate or standby though, I recall soundblaster threads about that.. not sure models... But if you want to know the cards low level output it would be in the vicinity of 0.3V-0.35V, not sure your amp type but check the model number in google to see what it's Nominal Voltage input range would be on preamps as if it's a lower grade amp the .3v would not be sufficient enough which can cause "whining" or buzzing noise in speakers. I have a Sony and it's min voltage range is .3V I simply turned up the gain to compensate the low voltage and it sounds loud, very loud! no noise..

Low voltage outputs do not cause a ground loop ("whining" or buzzing noise in speakers). They are closer to the noise floor making ground loops more noticeable compared to the signal, but a ground loop is a ground loop. ""whining" or buzzing noise in speakers" are caused by induced alternator RF interference through the signal path (running power wires next to RCAs), poor circuit design (Not isolating/insulating the signal path from noisy power) or a ground potential variance (One component's resistance on the ground path is higher than another, causing the unit to ground through the RCA ground instead). The later being the most common from poorly installed components.

My advice to the OP, amplifier is required. DO NOT shop by numbers or wattage. Inexpensive can easily mean cheap. I would recommend finding something used, with at least 25 watts per channel X 4. A lot of the used Alpine amps are a great buy for what you're after.

Installation is just as important as amp quality. Have it professionally installed. Study what they did to learn more.