Got A Classic Oscope

[Noobtastic14]

1) then by ur rational u need to burb ur setup from 30-80hz.... find the lowest impedence rise... and set ur gain at that frequency since it will be seeing the most power at the lowest resistance....

ive set many amps with a dmm and thats it...

sometimes a little clipping indicator but i have always used 50hz at 0db...

if u are ballsy use a -3db 50hz tone and u should be fine......with no speakers connected

it be better to set up the amp this way... then find ur impedance rise... then reset gain if need be

2) what cd are u using and why are you using a track 14 with -10db.. and -10db of what..50hz?

3) why is it set at 28v... arent u powering the mx w/bxi1606d...

the CD i'm using is the Rockford Disk that is for a 360.2 setup

the CD has a subwoofer tone, full range tone, and tweeter tone and the sub tone is 40hz i tried to follow the directions listed in the pinned topic "setting gains with an Oscope" im just wondering if i did anything wrong- when i get a chance i'll do it again without the woofer wired

-Drew

[The Loud One]

We recommend that the speakers be unhooked because it can damage them playing test tones, especially when the signal is clipped.

Nice job on the videos. You are seeing a small amount of clipping with music as is to be expected, that is why the track is recorded at -10 dB. If you set your gains at 0 dB you would never clip and the system just wouldn’t play as loud. We have found -10 dB as a good trade off in the bottom end.

How does your system sound overall? Did the dynamics improve?

[Noobtastic14]

thanks! yeah it does sound much better, balanced and clean!

-Drew

[Decaf]

well it would help to have known about the 360.2... although -10db?

heres an example

sine wave available on roe.com - 40hz @ 0db

classic sine wave.. which usually are at 30db on audacity

ripped from Dj Unk album - 2 Step

27db@44hz... notice how its not clipped "a little"... this would show up as a clean sine wave + mid and highs

i tried to find a song with a note close to the one used on rf 360.2....

so the equivalent to ur gain setting would be as if u used a sine wave recorded at 20db instead of 30db... i just showed u that on dj unk's beatn down ur block that it is recorded 7db above what is suggested for music by rf 360.2... this would result in slight clipping because you would have set ur amp with a higher gain so it is more sensitive to the weaker signal recorded at 20db (questimation on rf sine wave tho, it could be more or less but not by much, 30db is the highest ive seen without clipping, so subtract 10 and my answer is justified)

hope that helps with concrete visual evidence....

Edited November 21, 2008 by decafcappucino

[The Loud One]

decafcappucino,

I'm not sure what you're driving at.....

We have a tuning cd with different tracks recorded at 0dB, -5dB, -10dB, -15dB. Each of these are at 40 Hz, 1 Kz and 4Kz. This is used to set the gain structure of any audio system. We have been dicussing gain overlap.

Gain overlap is a compensation mechanism to account for the fact that we don’t listen to test tones in mobile audio

systems, rather we listen to music. Test tones are great for setting up the input levels on each component of the signal

chain, but test tones are constant levels all of the time. Music has levels that simply are not constant all of the time.

There are loud passages and soft passages in music, and these are constantly changing. Due to this fact, the maximum

unclipped output levels determined by test tones will seem as if the system doesn’t play very loud. Certainly it’s free of

clipping and audible distortion, but it’s not as loud as it seems like it could be overall. This process allows a measured

amount of increase to be implemented without “guessing” by just turning up the gain controls on a random piece of

equipment. Adding extra gain to the signal chain whether it’s at an upstream signal processor or at the amplifier at this

point is a trade-off of benefits and drawbacks. Most people find that there is a good compromise of these trade-offs.

• When you raise the gain above the levels achieved with a test tone, you will lower the signal to noise ratio of the

system. In this scenario, the trade-off is higher output at maximum levels trading off for more hiss and system noise

with the volume at lower levels. There is always an acceptable compromise.

• Additionally, when you raise the gain above the levels achieved with a test tone, you will increase audible

distortion of the system. In this scenario, the trade-off is higher output at maximum levels trading off for more

frequent moments of “clipping” with both the volume and the music at their maximum levels. Check out the amount

of time that there is added distortion in the signal based on the amount of gain overlap added. Once again, there is

always an acceptable compromise.

• Add in 5dB of gain overlap to achieve a higher volume with music (rather than test tones). It’s a safe compromise

between slightly increased distortion (Less than 0.1%) and louder output (nearly 5dB). Less critical listeners could

tolerate 10dB of gain overlap, but look what happens to the distortion increase. Some people will easily hear that with

a great set of mid and high frequency speakers (certainly more evident on compressed audio tracks as well). Reserve

15dB of gain overlap for subs, if at all. If you are using this setting, chances are you can go to a bigger amp for better

sounding results at the same volume levels with less distortion and more headroom.

• Use the gain overlap tracks on the RTTI/3Sixty set up disc to achieve the gain overlap safely without causing damage to

the speakers. Simply play the same frequency (HP/BP/LP) as before and increase the voltage levels to the same place

the recorded measurements were at 0dB levels for 5dB of overlap. If you use the 0dB tracks to increase the output

voltages to do this, you will almost certainly damage the speakers if not using load resistors.

There is a complete tutorial at the top of this section that explains the procedure in more detail.

[meade916]

and THAT settles that! ^^^

BTW: before any of you argue, Mr. Cobbs is the Director of Rockford RTTI.....(in case u didnt know)

Thanks Greg for the great info!

[Noobtastic14]

x2!! thanks!! big difference in the subs going from 0db to -10db and i have much less clipping in music now than i have before.

-Drew

Edited November 21, 2008 by Noobtastic14

[Decaf]

im pretty sure i understand what ur saying... all im saying is thats not fool proof @ -10db because commercially available rap these says has plenty of data near sine waves

the difference between how u set ur amp and mine would be very little... u would just have turned the gain up a hair more... thats all im really gettin at... and that its something to be careful with.. but

i encourage gain overlap to an extent... it is well understood that sine waves are/have a louder/higher amplitude signal

im going to guess 100% that if i ripped the 40hz track recorded at -10db, on audacity or any other software, it would provide a plot spectrum showing ~20db of 40hz vs the original track at 40hz which would yield 30db...

all im sayin is commercially available rap music, which most of us listen to, has data well exceeding 20db... even 25db per plot spectrums... and in that case the gain would be set too sensitive and u would be closer to clipping than if set with a -3db, or maybe even a -5db track...

and i know "some clipping" isnt bad... but not many are even aware when its happening or what it looks like... and using -10db puts u closer then -3db

this is one of the reasons an accurate clipping indicator would be very helpful on rf amps... cough cough... or any other for that matter

on a side note it is pretty sweet that the sine waves are included in the 360.2

and believe me, in the near future i will be adding a 360.2 so this is very relevant to me... cant wait to go active

Edited November 21, 2008 by decafcappucino

[The Loud One]

You are right, nothing is fool proof. This is the method we use when setting up a car, -10dB on the bass and -5dB on the mids and highs. We have had good sucess with this. If you listen to lot's of bass heavy or compressed music use -5dB or 0dB.

"this is one of the reasons an accurate clipping indicator would be very helpful on rf amps... cough cough... or any other for that matter"

Be on the look out for some new products in 09.

[Decaf]

You are right, nothing is fool proof. This is the method we use when setting up a car, -10dB on the bass and -5dB on the mids and highs. We have had good sucess with this. If you listen to lot's of bass heavy or compressed music use -5dB or 0dB.

I'm glad we are on the same page... i wasnt doubting or arguing u... i wouldnt dare... just questioning the method cause ive been meassing with music alot lately and have found/learned alot

"this is one of the reasons an accurate clipping indicator would be very helpful on rf amps... cough cough... or any other for that matter"

w00t w00t w00t

Be on the look out for some new products in 09.

the cat's head is out of the bag... wheres the rest of its body..?