I know DEAD HORSE.. but if you feel like it,.. Help me with Class A/B vs Class D.

[Chromatic]

Instead of starting a new thread.. I just got my equipment in.. yay! Now,.. I'm going over this PPI 5 channel amp,.. and what it says for settings doesn't match up with what i actually has on the amp to select. There's mainly just one switch I'm not sure about.

Here's the amp buttons:

Now you see where it says [sT] - [4CH] ?

Well, that's a setting that's to select input.. Quoting from the manual: "Input Selector Switch: - Choose ST for single stereo input. This allows the front, rear and subwoofer channels to receive signal from ONLY the FRONT RCA Input. Choose 4CH for 4 Channel Input. This allows for Independent Front and Rear RCA Inputs, and the Subwoofer signal is taken from the Rear Channel Input. Select the 5CH to use all Five channels to use All of the RCA Inputs Independently for Signal Inputs. "

As you see,.. it has Front RCA inputs, Rear RCA Inputs, and SUB RCA Input. (Same as the back of my headunit.)

Here's the problem.. The picture is what my Amp looks like.

It does NOT have the 5CH selection. Just ST and 4CH.

That's not right. The amp should have the 5CH (5 Channel) selection because it's a 5 Channel amp. But it's just not built in, and the manual even says it has this "5CH" selection.

So What to do? Is the amp just going to use 4 channels now?

That's the more major issue.

But there are more issues on what it's supposed to have and what is actually on the amp.

See the Rear Crossover Selector Switch (Says LPF, HPF, and FULL)?

The manual says: "Rear Crossover Selector Switch - Choose to activate the High Pass Crossover, Low Pass Crossover, OR the Band Pass Crossover for the rear channels. Band Pass Cross-over uses the High pass AND Low Pass crossovers simultaneously."

Again.. It doesn't have the "Band Pass Crossover selection here. Just LPF, HPF, and FULL. I can live with this, because it's just a cross-over but still another oddity.

I don't like the fact that it doesn't have the 5 Channel Input Select due to it being a 5 Channel amp //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

Any thoughts? I went with PPI due to everyone recommending them due to their quality.. So hope this amp is fine,.. and the buttons somehow work like they are supposed to even though it doesn't have the switches,.. especially to put the input select to 5CH (5 Channel). I can see that being a problem, using 5 speakers, Front RCA's, Rear RCA's, and SUB RCA's.

 

[MXcarAudio]

This is how i will set up

input selector 4ch

rear dial lever (always whatever volts your head unit outputs)

rear put it on HPF

Front put it on HPF

subsonic to what ever tuning your box is

it looks like you have 3 gain control (level)

source sub

LPF by the protect light is for the sub

This is a 5 channel and the crossover can go as high as 4k ussually used for independent tweeters

 

[Chromatic]

This is how i will set up
input selector 4ch

rear dial lever (always whatever volts your head unit outputs)

Well it's blind.. so the "Level" has to be the same as Gain. I will tune it with my DMM and tracks.. 40hz sine wave for Sub.. and 1khz sine wave for fronts and rears.

Never heard of an amp without a "gain".. so Level = Gain.. no doubt about it.

The amp just isn't labeled right and/or the manual is incorrectly written. I don't know. I contacted PPI to make sure it will work in 5 ch mode,.. AND it doesn't have an option to simultaneously use HPF/LPF on the rear crossover (It should have Band pass selection),.. and it has LPF or HPF or FULL (no xover).

But, With those RCA's and three gains (levels), etc.. it's bound to work fine as intended. Sub I'll put on "Sub" and not "Int".

rear put it on HPF

Front put it on HPF

That's all I need for the front and rears.. so that's fine.. I'll keep 100Hz or so out of them.

subsonic to what ever tuning your box is

I have not researched this.. so I"ll ask -- What do you mean by "What ever tuning your box is" ?

I know this just filters out VERY low frequencies from 20hz-38hz.. The box is custom from SRQ.. How do I determine where to set this optimally?

it looks like you have 3 gain control (level)

Yup.. will set with tracks, eq/bass/treble at zero -- HU at 75%,.. and DMM.

source sub

Yup, thanks.

LPF by the protect light is for the sub

Yeah I assumed that, only makes sense with the layout. But thanks for confirmation.

This is a 5 channel and the crossover can go as high as 4k ussually used for independent tweeters

I see.. There are "component" tweeters.. but I think you mean literally those wires going to JUST a tweeter. I'll probably set everything at 100hz.. with front and rears getting 100hz and below cut out.. and Sub getting 100hz and above cutout.

Now -- still.. I need a way to figure out when I hit 100hz -- Can I play say.. 105hz sinewave.. and listen as I turn knob.. and when that track STOPS being audible I know I'm in the right spot?

Thanks

 

[MXcarAudio]

subwoofer box tuning, where are you getting the subwoofer box, like my sub box is tuned to 32hz, i set my subsonice at 30hz

 

[Chromatic]

subwoofer box tuning, where are you getting the subwoofer box, like my sub box is tuned to 32hz, i set my subsonice at 30hz

Talked with fabricator.. He said drop it to 20hz and leave the subsonic there.

 

[MXcarAudio]

not good to drop to 20hz subsonic

 

[Chromatic]

not good to drop to 20hz subsonic

Ok, explain. The Master Fabricator and owner of SRQ customs, Ryan Pepsin said for this Box to put it at 20hz subsonic. I need some clarification of why to deem his advice incorrect. I'm not saying you are wrong,.. just need a little more is all. You can understand my reasoning I'm sure.

 

[MXcarAudio]

if your subsonic is set too low you will bottom out the sub which is bad, under 25hz you dont ussually hear it anymore. whoever is building your box ask him what is the tuning of the box, if he does not know get a different builder

 

[Beatin' 10+ year member]

Speaking of AB and D class amps, one time I did a test with my system playing full tilt with the car on. I had attached one of those LED volt meters on the batt/alt and played music. I noticed the lights would flicker, particularly on the low notes. The lower the note, the more pronounced and slow the flicker was. Higher notes had the 14.4 bulb flicker faster but with less intensity.

Is this a direct result of the pulse switching technology used in D class amps? What would happen if I had a AB class amp?

 

[Chromatic]

if your subsonic is set too low you will bottom out the sub which is bad, under 25hz you dont ussually hear it anymore. whoever is building your box ask him what is the tuning of the box, if he does not know get a different builder

Box is done and with me now. This guy is well known for his work,.. he's one of the best out there. I trust him on the setting.

Also, what about all the amps that don't have a subsonic filter.. isn't that just as bad or worse?

 

[MXcarAudio]

all sub amp has a subsonic, i have not dealt with a sub amp that does not have a subsonic, i your guy is that well known he knows what tuning your box is and unfortunately he will not tell you to set it at 20hz

 

[Chromatic]

all sub amp has a subsonic, i have not dealt with a sub amp that does not have a subsonic, i your guy is that well known he knows what tuning your box is and unfortunately he will not tell you to set it at 20hz

Point made. I'll send him an email now and ask the question again,.. see what his explanation of 20hz is. It is a "custom" box that goes in an unusual spot, shrug.

 

[MXcarAudio]

Point made. I'll send him an email now and ask the question again,.. see what his explanation of 20hz is. It is a "custom" box that goes in an unusual spot, shrug.

from my understanding under 25hz its not audible anymore and its a lot of strain to the sub so its kinda useless

 

[Chromatic]

all sub amp has a subsonic, i have not dealt with a sub amp that does not have a subsonic, i your guy is that well known he knows what tuning your box is and unfortunately he will not tell you to set it at 20hz

This is what the Ryan at SRQ Customs said about the subsonic:

Here is why: Car audio subwoofers cannot play below 20Hz. The human ear cannot hear below 20Hz. Creating a roll-off point at 20Hz keeps the amplifier from wasting energy trying to play notes that the sub cannot reproduce and your ear wouldn’t hear anyway. If for some reason you had a recording with a lot of subsonic information, it could damage the woofer trying to play it. Subsonic is really useful in a ported enclosure, and you would set the value to the tuned frequency of the box. For sealed, I set them all at 20Hz.

 

[MXcarAudio]

its up to you, i never set my subsonic that low, lowest i did was 25hz, mine is set right now at around 30hz