alaskanzx5 Posted October 22, 2012 Report Share Posted October 22, 2012 when having a high output stereo in a car everything has voltage drop. if the headunit isnt getting the power it needs i would only assume the rca voltage would drop aswell. Quote t1500bdcp 2 t2d4 15" 1 t600.4 1 t400.2 1 set p1 tweets singer alt, tons of wiring, smd vm-1, 80prs, back seat delete, still in the works, aiming for a 145-147 with the ability to play 25hz up to 50hz. Link to comment Share on other sites More sharing options...
TonyD'Amore Posted October 23, 2012 Report Share Posted October 23, 2012 so in the end if you have a cd player with a 6 volt preout and a cd player with a 4 volt pre out and the amp can be set to 50volts with out clipping and has an internal gain of 10 volts the cd player with the 4 volt pre out would be able to allow you to push you equipment to its max with out clipping while the cd player with the 6 volt preout would create more clipping and only hurt the output and sound quality of the system. I noticed this personaly on my own ride. I have Chrysler 300 with the stock HU that has a Rockford BLD (3Sixty Line Driver) for the added sub stage . My sub stage is a fully upgraded single 10" DC XL m2 running off a DC 2.0k. The line driver has 2 modes Balanced and Unbalanaced. In Balanced mode it produces 22 Vrms and 11 Vrms in Unbalanced mode. When setting my gains (line driver hace a gain as well) with the DD-1 , I noticed that in balanced mode I get full time distortion on 0db 40hz track. But in balanced mode I can addjust the gains slightly (if at all). Also when I set the amp if I use the -5bdb track on Unbalanced mode I'll get full time distortion decteted on my DD-1. The reason the BLD is 11 Vrms unbalanced and 22 Vrms balanced is because in unbalanced mode it puts up to 11 Vrms on the center pin of the RCA and grounds the shield. In "balanced" mode it puts 11 Vrms on the center pin of the RCA AND 11 Vrms on the shield!! If your amplifier doesn't have balanced or differential inputs, you are shorting the BLD out in balanced mode. Take a digial meter, set it to ohms, with the amplifier not turned on and the RCAs disconnected measure the resistance from battery ground connection to RCA shield. Let me know Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted October 23, 2012 Report Share Posted October 23, 2012 (edited) CJ, you've Peaked my interest here. Is It unreasonable to think there's head unit voltage drop? AC voltage output X amplifier internal gain. Scenario 1: .35VAC x 10 Scenario 2: 10VAC x .35 Assuming amplifier internal gain is a constant, voltage drop at the headunit is going to change which scenario more? The RCA output voltage will not drop with B+ voltage dropping. The RCA outputs are fed from a mini-amplifier inside the headunit that has feedback. Think of it as regulated Edited October 23, 2012 by TonyD'Amore 2 Quote Link to comment Share on other sites More sharing options...
CJ18 Posted October 23, 2012 Author Report Share Posted October 23, 2012 With all of that being said, what would or could be the reason for a .5db increase in score? The TL doesnt lie. All setting the same for both tests and amp tuned with dd1 with same track for both test. 6Vac input voltage- 155.71db .33Vac input voltage- 156.17db Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted October 23, 2012 Report Share Posted October 23, 2012 With all of that being said, what would or could be the reason for a .5db increase in score? The TL doesnt lie. All setting the same for both tests and amp tuned with dd1 with same track for both test. 6Vac input voltage- 155.71db .33Vac input voltage- 156.17db I don't know CJ, we are talking 0.46dB. If the voice coil temperature changed between runs you might see this. Can you get those results consistantly? Quote Link to comment Share on other sites More sharing options...
CJ18 Posted October 23, 2012 Author Report Share Posted October 23, 2012 I will find out for myself as soon as I get my truck up and running. Not really a big deal for me building a daily system, but for guys chasing a number, this is a cheap .46db in the case of this test. 1 Quote Link to comment Share on other sites More sharing options...
CJ18 Posted October 23, 2012 Author Report Share Posted October 23, 2012 I may actually test this for myself tomorrow. I will hook up my 1.2k in my truck and just run wires to the sub in my explorer to see what happens. I am curious to see if I get the same results. I will make sure to give the sub plenty of time to cool down between runs. Quote Link to comment Share on other sites More sharing options...
8ight Posted October 23, 2012 Report Share Posted October 23, 2012 CJ, you've Peaked my interest here. Is It unreasonable to think there's head unit voltage drop? AC voltage output X amplifier internal gain. Scenario 1: .35VAC x 10 Scenario 2: 10VAC x .35 Assuming amplifier internal gain is a constant, voltage drop at the headunit is going to change which scenario more? The RCA output voltage will not drop with B+ voltage dropping. The RCA outputs are fed from a mini-amplifier inside the headunit that has feedback. Think of it as regulated Was going to say... Quote I'm gonna hate Link to comment Share on other sites More sharing options...
Blackedout Posted October 23, 2012 Report Share Posted October 23, 2012 CJ, you've Peaked my interest here. Is It unreasonable to think there's head unit voltage drop? AC voltage output X amplifier internal gain. Scenario 1: .35VAC x 10 Scenario 2: 10VAC x .35 Assuming amplifier internal gain is a constant, voltage drop at the headunit is going to change which scenario more? The RCA output voltage will not drop with B+ voltage dropping. The RCA outputs are fed from a mini-amplifier inside the headunit that has feedback. Think of it as regulated Thank you Tony. I appreciate the feedback. To expand on it, if possible, what makes the AC voltage output from the 'mini amplifier' in the head unit different from that of the AC voltage output of the amplifier in the back? Quote Trunk Build Log Link to comment Share on other sites More sharing options...
basebalz13 Posted November 7, 2012 Report Share Posted November 7, 2012 .46 DB increase, is a HUGE increase at that SPL level. Different voice coil temps, or whatever is not going to make a .5 db diff. Maybe in a Extreme vehicle. Cody, Every amp has a sweet spot, A spot the gain likes to be. Also try messing with the phase if your just running 1 amp, or 2 amps strapped. If your running more than 2 amps strapped dont because you wont be able to achieve the same phase on each master amp. Quote My Facebook- http://www.facebook....m/#!/basebalz13My Twitter- @DB___Designs (3 underscores) Jay Henderson's 'Blue Hurricane' F-150 6 18s 4th order- http://www.stevemeadedesigns.com/board/topic/135451-hot-girls-oh-and-alphasig293s-rebuild-6-aa-mayhem-18s-2-cactus-k12-30k-rms-f150-pics-fixed/ Trippi Congo's Hummer- http://www.stevemeadedesigns.com/board/topic/141430-trippis-hummer-the-final-chapter-eye-candy-on-page-36-52/ Brandon Springle's Accord 4 18s 4th order- http://www.stevemeadedesigns.com/board/topic/179046-honda-accord-4-18s-4th-order-tdh-member/ Cody Johnson F-150 8 15's 4th order- http://www.stevemeadedesigns.com/board/topic/179931-cody-johnsons-f-150-8-15s-4th-order/ Link to comment Share on other sites More sharing options...
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