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View Full Version : took out my eq/line driver, really did lose spl.



ktraughb
05-17-2012, 06:21 PM
ive been using an eq with an 8 v line driver. i was never sure if it actually produced a measurable spl difference. well, my head unit has had noise issues ever since i bought it used (improper rca ground internal), so i decided to remove the eq to see if the problem would get better worrying that i was actually only creating more noise with the increase in signal. it did help to eliminate the noise a little bit. its not completely gone, even with the rcas grounded, however it also dropped my spl score. i basically tested this for reference to find out. single dd 3512 on a 2k rms amp. score with the eq/line driver was an even 143 sealed on the dash. score after removing and setting eq on head unit only, 141.5 sealed on the dash. (term lab tests) i couldnt repeat the 143 to save my life with all factors the same. heres the kicker---my ear meter actually thought that this was louder without the eq/line driver. i mean i thought there was a HUGE difference in my bass output without the eq/line driver. i guess thats why we use the term lab instead of the ear. just found this interesting, thought id post it up.

n8skow
05-17-2012, 07:00 PM
Without having measured your amp's before/after power output, hard to say what's changed... but the line driver does not magically make your amp create more power. It's possible you were producing cleaner power (with the stronger input signal) which will generally result in more spl on the meter.

keep_hope_alive
05-17-2012, 11:31 PM
in order to realize the amplifiers full potential, you need a careful combination of signal gain and amplifier gain. after you removed the line driver you could have increased amplifier gain. that could have safely gotten you back to 143.

bikinpunk
05-18-2012, 12:37 AM
did you re-adjust the gains at the amp?...


Also, you said 'HUGE' differences. 1.5dB isn't really huge. That's not even half power... much less half as loud (10dB). I'm not saying you're crazy... obviously you've done due diligence to see if the data is right (which I appreciate), but it seems to be the first thing you should have done is to readjust your amplifier gains to get you to the same output voltage you had before (and this output voltage should have been measured with some tone, no load at the amp, before the line driver was removed).

CAT MAN
05-18-2012, 01:05 AM
did you re-adjust the gains at the amp?...


Also, you said 'HUGE' differences. 1.5dB isn't really huge. That's not even half power... much less half as loud (10dB). I'm not saying you're crazy... obviously you've done due diligence to see if the data is right (which I appreciate), but it seems to be the first thing you should have done is to readjust your amplifier gains to get you to the same output voltage you had before (and this output voltage should have been measured with some tone, no load at the amp, before the line driver was removed).

are you retarded? 1.5 is huge. let me see you gain 1.5 easily

keep_hope_alive
05-18-2012, 01:25 AM
are you retarded? 1.5 is huge. let me see you gain 1.5 easily

No, bikinipunk is not retarded. Humans can barely distinguish a change of 2dB side-by-side. But our ear's dynamic range can shift our perception of loudness.

It is not a "huge" change. The mathematical formulas governing logarithmic mathematics say so.

The loss of 1.5dB was most likely due to a reduction in signal strength which is a reduction of amplifier power. Gaining that back is as simple as increasing signal strength.

So yea. Pretty easy.

Kangaroux
05-18-2012, 01:32 AM
No, bikinipunk is not retarded. Humans can barely distinguish a change of 2dB side-by-side. But our ear's dynamic range can shift our perception of loudness.

It is not a "huge" change. The mathematical formulas governing logarithmic mathematics say so.

The loss of 1.5dB was most likely due to a reduction in signal strength which is a reduction of amplifier power. Gaining that back is as simple as increasing signal strength.

So yea. Pretty easy.

This. I believe the threshold is something along the lines of 3dB to be able to tell if something is louder or not.

hispls
05-18-2012, 01:56 AM
I have noticed similar phenomenon with Zenon based class D amps. Definitely would do more on the meter (even after adjusting gains) with line driver.

The meter doesn't lie

bikinpunk
05-18-2012, 10:17 AM
are you retarded? 1.5 is huge. let me see you gain 1.5 easily

in the realm of context (which you avoided), 1.5dB isn't huge. Even the OP seemed to acknowledge that it wasn't a huge audible difference and I backed that up.
With numbers only, that high up, every little bit counts, I agree. But audibly, 1.5dB is nowhere near huge.


my ear meter actually thought that this was louder without the eq/line driver. i mean i thought there was a HUGE difference in my bass output without the eq/line driver. i guess thats why we use the term lab instead of the ear. just found this interesting, thought id post it up.

ktraughb
05-18-2012, 03:00 PM
to answer questions, yes i tried testing both adjusted/non adjusted as well as bass boost. not an ounce more. and yes, 1.5 db is a huge difference. i normally do spl competition, obviously not with this system, but 1.5 is a huge drop gain in competition. difference between first place and somewhere way off the charts usually.

ktraughb
05-18-2012, 03:05 PM
in the realm of context (which you avoided), 1.5dB isn't huge. Even the OP seemed to acknowledge that it wasn't a huge audible difference and I backed that up.
With numbers only, that high up, every little bit counts, I agree. But audibly, 1.5dB is nowhere near huge.

it was actually the opposite. audibly to me, i thought it was a big difference (louder with no line driver). obviously it wasnt. and im sure this can be attributed somewhere along the line of not clipping the amplifier and things of that nature. some spl guys have shown best results without clipping. some clip the **** out of their stuff and theyre loud as hell, too. higher input voltage and less gain may be less clipping, cant say i ever measured it with this system. yes the bass did sound cleaner with the eq/line driver installed. the strange thing about my amp is that gain difference even on head unit from about 1/3 turn, to 3/4 turn hasnt yielded audible or termlab spl differences. could be a fucked up up amp.

keep_hope_alive
05-18-2012, 10:49 PM
likely it's just an example of the human ear's moving range. we are terrible instruments. "loud" is relative

ktraughb
05-19-2012, 12:53 AM
this is true. im fooled all the time by what i hear and the term lab meters. i sometimes think things are way quieter than what they meter, too!

PaulD
05-21-2012, 05:44 PM
to answer questions, yes i tried testing both adjusted/non adjusted as well as bass boost. not an ounce more. and yes, 1.5 db is a huge difference. i normally do spl competition, obviously not with this system, but 1.5 is a huge drop gain in competition. difference between first place and somewhere way off the charts usually.

I was gonna say, in SPL comps a 1.5 dB difference can be the difference between 1st and 4th or 5th place. If you are just trying to annoy those around you, probably not a big deal.