fonto

iTrader: (1)

Ok, at a VERY small Socal meet VNlilman and I conducted an experiment that we talked about at the end of this thread. Well it turned out to be true! I went to Pepboys and bought some of the lower end monster splitters. I normally have two RCA inputs pluged into my JBL BP 1200.1 amp, but according to the thread on ClubRSX if you split two RCAs into 4 and use all four inputs on the JBL the amp will put out more power.

So I tested it with the splitters and it did sound a lil louder at a lower volume level. So I put the inputs back to two...the I put it to 20 on the volume and VN and I sat in the car. The I switched it to the 4 input configuration with the splitters. It turned out to actually sound louder to us at 20 on the volume level. My subs seemed like they were starting to distort at 20 when they would usually distort at 28. I can't explain it, and maybe someone else could, but I am now a beleiver.

I hope this makes sense...I am really tired right now, but maybe if this is incoherent I can be clearerr tommorow.

VNlilMAN

iTrader: (7)

ya i dont know how or why but it worked... worked for like 5 other people on the clubrsx.com board...
i think it was actually louder and not just a placebo effect

fonto

iTrader: (1)

...basically it means that I can/should turn down my gains if I keep the split four input. I went to Fry's after and got some better RCAs, and I think I will return the others.

For anyone who want to try this Monster spliters are really easy to take out of the box and put them back in like they were never used if you want to experiment with this.

This info may be useful because a lot of poeple on here have mono JBLs on this board.

VNlilMAN

iTrader: (7)

how much were the rcas at frys?

fonto

iTrader: (1)

...7 dollars for the monster junior interlink, and I don't want to say how much I paid for the Monster competition series I bought

Mystic3030

Intresting...is it something thats only supposed to work with JBL amps? If so it must be something with the way the amp is wired inside....and why does a monoblock amp have two sets of RCA inputs?

LudlamTheory

monoblock has 2 sets of inputs and outputs so the bass is nonfading. youve got to agree that the jbl bp series is a budget amp, and a lot of budget hu's have no sub preouts.

fonto

iTrader: (1)

apparently the speaker lever inputs can be used along with a set of RCAs too.

hmm, I guess as long as it works don't question it?

tbone323

What you guys are doin is simply clipping your amp earlier. The inputs of your amp are summed together. What it sounds like is that you are injecting signal into your PREAMP OUTPUTS on the JBL. Basically, the pass-thru outputs are not buffered, esentially acting as a Y-splitter inside the amp. If you send signal into 4 inputs instead of the 2 that you normally do, you are doubleing the input voltage goin to the amp. Your amp can only play so loud, reguardless of what you THINK you are doin to "trick it". The amp sounds louder at lower volume levels on your deck BECAUSE IT IS LOUDER. You said that at 20, your speakers distort, this is your amp clipping (not so good for your speakers although it does give the illusion of being louder and moderate levels of clipping are usualy the preferred sound in car stereo's)

You can get the MAX power out of your amp with the minimum # of inputs and lowest level of signal, simply by turning up the gain. The gain, known as Sensitivity, is only there because the inputs values can range from deck to deck.

So, why then you ask would you want to have a deck that puts out 5V (as apposed to 200mV) if you can get the same power from the amp? [Don't tell me you're NOT thinkin this, lol] Well, the larger the signal you send to the amp, the less noise (created inside the amp) will affect the signal, AKA SNR - signal to noise ratio. You want a lot of signal into the amp (line drivers are used for this) and the gain turned to the lowest level. This will insure the cleanest possible signal delivered to your speakers.

Sorry to go on but i'm just bored i guess.

~Tbone

VNlilMAN

iTrader: (7)

i dont know too much about car audio so correct me if i'm wrong... how are you doubling the input voltage by splitting it? say a headunit only outputs 14v whether your only using 1 pair or 1 pair with splitters.
i would think the same voltage goes through the rca cable(whether or not i has splitters) and splits the voltage among the splitters no?

fonto

iTrader: (1)

So T-bone...

tbone323

The amplifier sums all of the signals that it sees. If you send a 1V signal to 2 inputs, they get summed and create 2V INSIDE the amp. I don't have the schematics for the JBl line of amps so I can't tell you exactly what they are doin internally, but my designs sum the inputs (as do most others). The fact that distrotion occurs sooner AND the speakers play luder at lower head unit volume levels indicate that this is what is really happening. If there were 8 RCA's on the front end of the amp, then you'd proly reach clipping at 10 on your head unit instead of 20 (with using 4) and 28 (using 2).

VNlilMAN

iTrader: (7)

"The amplifier sums all of the signals that it sees"
ya i get that but a headunit can only send out what it can put out right? so if the headunit can only send out 1v to a pair of rca's, it still only sends out 1v to a pair of rca's with splitters.

how does the signals work anyways? if a headunit is rated at 1v, can you send it to 16 different inputs and they all get 1v? or if you send it to 16 different inputs they get 1/16v?

tbone323

here, rather than put it in my own words, here is a nice tutorial of what I am talking about...

http://www.play-hookey.com/analog/ex...amplifier.html

~Tbone

MangoEX

iTrader: (2)

So the less RCAs, the better basically? Also, you mean more rcas multiply the wattage? they act as amplifiers?

tbone323

NO..let me state this as simple as possible. The GAIN control on an amplifier is only used to match the amplfier with the partcular source unit. Some source units put out 5V, some only 150mV. If you had both of those extremes (and by extreems, I do not mean that is the highest/lowest voltages out there, not even close really, just some #'s I'm using for this) if the amplfier had an input rating of 150mV to 5V, when you had a deck that only put out 150mV, you would need to turn the gain all the way up. On the other hand, if you had a deck that put out 5V, you wuld trun the gain all the way down (to achieve the amps rated power).

If the amp has 2 RCA inputs and you only use 1, you will just have to turn the gain up 3dB to get the same output power. You can't magically create more power by stuffing more signal into the amps inputs, the amp can only put out a signal so big before it clips (aka DISTORTION).

FaintReality

Not the case with JBL amps... Use all 4 inputs if you want to get the full potential out of your amp. It is not clipping the amp sooner! This has been talked about and tested by hundreds by several people on alomost every audio forum (not just car audio forums) since I posted that at clubrsx. It says it in the JBL manual, just in a confusing way.

And for those who disagree... please go use the JBL amp first before you make your judgement! I though it was very weird indeed, but its a cheap ghetto amp and thats hot it works.

FaintReality

Edited to make more clear so that I don't confuse anyone!!!

Your subs are now distorting at a lower volumes since your amp is now putting out more power using all 4 rca inputs... If you had your gains setup previously so that the amp puts out max power at say 75% on the volume ****, it might now put out max power at say 60% on the volume ****, so you will need to re-adjust your gains to accomidate for the increase in voltage from using all 4 rca inputs on the amp.

tbone323

According to the JBL website..."The BP150.1, BP300.1, BP600.1 and BP1200.1 are desgned to provide constant bass regardless of the source units fader setting...If nonfading bass is not important in your system, connect a pair of inputs RCA or speaker level to either the front or rear input connectors on the amplifier"

This is EXACTLY what I have stated in previous posts...the amp will SUM the inputs of ALL the RCA inputs. This way if your fader is set so that more signal is goin o the front channels, the amp will still produce the same amount of output since the rear channel RCA signal will be decreased by the SAME AMOUNT that the fronts have been increased.

~Tbone

tbone323

WHAT?

r u serious? If you think that you are truely correct, please state your reasoning for such a statement, we would all appreciate it!

~Tbone

FaintReality

Say your gains are set up so that the amp will not clip till you exceed 75% of the HU's volume. Now when you use all 4 inputs on the amp, there is going to be a voltage increase, so now your amp is putting out more power... so at 75% of the HU's volume where it was previously adjusted before clipping, it would now be clipped since it might put out full power at say 60% on the HU's volume.

Percentages above are for examples only!!!

tbone323

ahhhhhhhhhhhhhhhhhhh, ok, i gotcha, i didn't understand what you were trying to say before.

FaintReality

Sorry! After I re-read it, it was confusing so I edited my post!!!