Pre-out Discussion

[slick rick 10+ year member]

how could i check for 34.7 volts? what equipment do i need?

 

[buster 10+ year member]

Thanks for the help. How do you figure out where your HU starts to distort? Do you turn the gains all the way down and crank the radio til it starts?

 

[forbidden 10+ year member]

It is a pretty safe assumption that most (not all) companies build there equipment to hit a price point, that said it is also a safe assumption that these same companies usually apply their voltage at a 1000hz peak and it falls off steeply from there. While it takes little power to drive top end (15 watts can make a tweeter wail) the exact opposite is true for subs. If the preout voltage drops off above 1000hz it is usually noticeable to most people but nowhere near as blanently obvious as the same drop off in the lower frequencies. Subs need power and if you have a low input signal from the word go, you are facing an uphill battle. This is where a device like the Audio Control Overdrive line driver is primarily used on the sub channel, to take that "4volt" preout up from the real 1.5 volt that it is to a 5 or 7 volt true preout, somehting that has much more flexibility for the user.

Jmac, no worries, where are you at right now? I have a new RX8 ripped to pieces and have just found neumerous issues that have stumped many a person, turns out it looks like a bad 6XS that may change the way Audio Control tests their gear. This car is a royal pain the butt. I've got a RSX waiting to get in here later today.

 

[denim 5,000+ posts]

hey all you need to know is more is better, Badda bing badda boom thats it

 

[forbidden 10+ year member]

Buster, keep hanging around, you pick up things really quick, your right again. Turn the gains all the way down. Take your favorite cd and play the same song over and over again. Start by turning your bass / treble etc back to 0. Make sure you do not have a bass boost engaged on an amp etc. Start by turning volume up on the cd player until about 80%. At this level is where most cd players will start to clip the output voltage. This is important - just because the volume knob reads say 35 at max power does not mean that it has to be played there. Just like your car has a redline, what would happen if you tried to do 100 in first gear, you would be way past redline, correct? The trick is to assume that 80 - 90% on the volume dial is full power, once the volume is turned up to this level you slowly start to turn the gains on the amp(s) up one at a time. If you have a 4 channel amp and subs, start with only the front rca's pluged int. Set the gain, unplug and move onto the next set. Once both front and rear are done, listen to them, if the back is more prevalent, then you may want to back the gain down (front stage - rear fill). Now adjust the sub gain the same way. This is not rocket science, nor gospel, but it is a simple way to get you going safely.

 

[helotaxi 5,000+ posts]

You could always measure the AC voltage on the amplifier outputs (while wearing hearing protection) ...
2 ohms - 34.7 volts for 600 watts

1 ohm - 24.5 volts for 600 watts

For your JBL BP600.1 ...

Or rather than risking your hearing and your speakers, you could just disconnect the speaker leads. Voltage is voltage. Potential exists whether there is current or not. V=IR. For a constant voltage as R goes to infinity (open circuit), I goes to zero. Voltage remains the same.

 

[maylar 10+ year member]

does anyone know how pioneer rates the 8500 or their middle-upper end h/u's voltage at? because i have my jbl 600.1 (which has crappy tuning knobs on it) on my 8500 and id like to find a definitive way to set it so i can get the most out of my system. is there any sine wave tune i can use to find otu where clipping is?

Dunno about those models, but the low end Pioneer I have is rated at 2 volts and actually only puts out 0.4 volts with a 0dB CD in the player and volume control set to 45 out of 60.

2 things to say about that:

1) Volume controls are logarithmic and the output voltage increases rapidly toward the top of the setting. Do ~not~ expect to see 3/4 of the rated output voltage at 3/4 volume. It could be way less.

2) I picked 45 as the HU setting because I use the deck's internal amps also, and that's where they just begin to clip (as measured with a 'scope and 4 ohm load). The preouts didn't clip at that level and probably would reach 2 volts at full volume.

 

[slick rick 10+ year member]

Or rather than risking your hearing and your speakers, you could just disconnect the speaker leads. Voltage is voltage. Potential exists whether there is current or not. V=IR. For a constant voltage as R goes to infinity (open circuit), I goes to zero. Voltage remains the same.

so id just put the positive and negative ends of the multimeter into the + and - of the speaker inputs in the amp? if im way off its because i dont know much about electronics and voltage yet.

 

[slick rick 10+ year member]

Dunno about those models, but the low end Pioneer I have is rated at 2 volts and actually only puts out 0.4 volts with a 0dB CD in the player and volume control set to 45 out of 60.
2 things to say about that:

1) Volume controls are logarithmic and the output voltage increases rapidly toward the top of the setting. Do ~not~ expect to see 3/4 of the rated output voltage at 3/4 volume. It could be way less.

2) I picked 45 as the HU setting because I use the deck's internal amps also, and that's where they just begin to clip (as measured with a 'scope and 4 ohm load). The preouts didn't clip at that level and probably would reach 2 volts at full volume.

is that where the h/u clips in gereral with the internal amp, or how you have your settings with low,mid high, etc? i hav mine set on 48 and havent heard any distortion with my cdts yet.

 

[adam71 5,000+ posts]

Like the Pioneer Premere series is 4V while the lower models were 2V.

The Premier head units such as my DEH-P930 claims it has 6.5 volt pre outs. Is that just a peak rating and they are 4 volt RMS..??? That would make sense since Pioneer likes to assume everyone for idiots by boasting the peak output of everything they make. They make good stuff and I wish they would find someone else to write their product description literature. They sound like they're talking to a 12 year old.

Am I the only one whose noticed this about Pioneer.

Sorry for ranting. Don't forget to answer my question though Maylar. Please.

Adam //content.invisioncic.com/y282845/emoticons/bowdown.gif.b85b23b82970bd22fb6b549c3392f016.gif

 

[denim 5,000+ posts]

I feel stupid ... But thank you //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

it happens to the best of us //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[maylar 10+ year member]

Single-ended drivers (RCA's) from a 14V power source can only put out 7V peak, or about 5 VRMS. Typically they spec 4 VRMS before clipping. If the spec says 6.5V, it's probably a peak number.

Using bridged drivers (balanced) that voltage limit is X2.

Getting more than that requires either boosting the internal power supply to the driver, or using transformers. Both methods cost money, so high preout voltages are only found on high-end models.