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

[trumpet 5,000+ posts]

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

Do as Ryan said.

 

[Chromatic]

Do as Ryan said.

That is what I've done.. I preset everything on the amp before installing it (amp goes in tomorrow).. And, among those was setting Subsonic to 20hz .. I trust Ryan given his reputation and his responses back to me that show he knows what he is talking about down to details that I am not familiar with (super technical). But, I've heard great things about him.. he's been at this for a LONG time,.. He engineered/designed the box.. and he built it. He's further installed this same custom box in several 350Z's personally, so I really don't know who better to get that advice from than the designer and fabricator himself?!

At any rate I appreciate the recommendation to NOT set the subsonic to 20hz,.. made me re-question him about it and he didn't waiver on the setting it at 20hz.

If any are curious at how things are coming along.. here's a build log/pictures I put up a minute ago:

http://www.caraudio.com/forums/car-audio-build-logs-cars-trucks-suvs/598484-2008-350z-installation-process.html -Click for Chromatic's Build Log.

Take care,

 

[trumpet 5,000+ posts]

A sealed enclosure doesn't really need a subsonic filter. The purpose of that filter is to prevent the woofer suspension from unloading below a vented enclosure's Fb, or port tuning frequency. It would be a different discussion if you bought a ported enclosure, as people have different recommendations for a subsonic(infrasonic) filter. Like Ryan said, it's very rare that music will ever have information below 20 Hz, but a subwoofer in a sealed enclosure at least has a chance of playing it without bottoming out.

 

[Chromatic]

Just have to say I got to the point of firing it all up tonight. And,.. the PPI 900.5 Class D 5 channel amp performs beautifully.. Nice and clean, runs cool,.. And it powering 2, 1" JBL tweeters, 2 JBL 6.5" mids, 2 (German) MB Quart 1" Tweeters, 2 MB Quart 6.5" Mids and 1 JL Audio 10" Sub.

Keeping in topic,.. The amp as said above was definitely the right choice for a $200 Amp to power all of this.. and in a spot that doesn't have the best airflow.. A class A/B may have gotten a little hotter than I'd like. No regrets. (This doesn't downplay the quality of the Ct Sounds I was going to initially go with,.. but I primarily went with PPI due to shifting to Class D power due to limited space and lack of airflow where amp is located.)

As for the Sub.. Well, it sounds unfreakingbelievable! How one 10" JL sub with 300watts on it, in a .66 Cubic Ft. Custom box that fits in a factory bulk head BEHIND my driver seat (can't see the sub, or any other equipment besides headunit when you get in the car!) -- Has such Sound quality, power,.. and is so TIGHT is beyond me to be honest. The sub was $109.. that's a bargain to me.. I know many said stay away from JL Audio.. but I have to say I'm absolutely blown away by it. It's absolutely perfect for what I wanted, only 100 times more "powerful" than I needed.

I'm also quite glad I decided to custom (well I guess running it into the center console instead of just throwing it back with the amp is "custom") fabricate the console to fit the Bass Knob,.. I can already tell I will be dialing it up and down quite frequently.. so being right in my reach and rather "clean" looking is something I really will enjoy.

So,.. with the subsonic discussion.. I left it at 20hz.. and pushed the volume up to where I set the gains with the speakers going.. to detect for distortion, etc.. and the sub is most definitely FAR from bottoming out in the sealed enclosure.

One thing I noticed that I didn't expect initially was the test tones I used to dial the sub in.. I was told to use a 40Hz tone to dial the sub in on this forum. So I did initially.. Set it to the proper voltage.. even backed it down about 1v .. Then when I had all speakers dialed in and was tweaking things to actual music I listen to.. The sub was VERY dissapointing.. I knew it wasn't a question of the sub just being that "weak".. I knew something was going on with the power it was getting while listening to that music (Was Led Zeppelin Over the Hills and Far Away, as it got into the chorus)..

So I put the Meter back on the sub speaker terminal and it was reading 10-15volts LOWER than where it should have been (remember I was playing it at the volume I set the gains at.. which was 30.. (My headunit goes to 40). ) So, I don't know if this is right,.. but I just assumed that I set gains to a tone that's more present in Rap and other types of music and not so much rock.. So I turned it off, unhooked speakers,.. and played a 79Hz sine (I figured 1 hz under the 80hz crossover was smart?) .. Reset the voltage for the wattage to sub on that ~80hz sine wave.. instead of the prev. 40hz.. Then plugged speakers back in.. and WOW,.. Sub came to life.

So am I right that the 40hz was just too "low" for the kind of music I listen to (Rock/alternative mostly.. with zero rap or "boom boom music" ) ? So when I tuned to a higher frequency on the gains it was set to give the proper RMS power more in the range of the kind of music I listen to?

It's the only explanation I can think of for the difference... and IF TRUE,.. frankly,.. Is quite an important thing for new people to setting gains with a DMM to know. IE: What kind of music do you primarily listen to? Ok,.. If say "Rap" .. tune to 40-50hz.. when setting gain.. If Rock,.. tune to 79-80hz.

I took my time being careful with this.. As I have been with the whole install (which is why I've put 30hours into it).. So I looked at how I'd put the DMM on the terminals while playing the sine waves.. and I just said, why not put the leads in pos. and neg. speaker terminals (one at a time),.. and screw down lightly to hold the leads in place?

Did that.. and that freed up my hands to fiddle with the headunit and the meter was positioned where I could easily glance at it. Made the job very easy,.. even if it took a little longer to unscrew and move the terminals instead of "touching them with hands".

I didn't want to just lay them on the terminals.. As I remember with a friend metering his amp (I didn't know exactly what the process was then).. he just propped them up on the terminals.. the two terminals fell and caused Pos and Neg to connect,.. and the amp immediately went into Protect mode. Didn't harm his amp, but I didn't exactly want to throw the brand new amp into protect mode if I could afford it.

Besides.. who doesn't have 15 minutes to put leads in the screw sockets for FR/FL, RR/FL, and SUB? (And in many applications just FR/FL and SUB) ?

Of course two people would be the "ideal" scenario. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I still have this grin on my face and the interior isn't put back in yet.. The sound I got after setting up the crossovers and headunit Parabolic EQ, and other settings was utterly amazing to me. I wanted to just sit in that stripped interior (without a seat lol).. for hours listening. Can't wait to get this interior back together and take it out for a proper drive.

I truly appreciate all of you guys help the past 4 weeks or so as I asked all the questions. It paid off with a result of a complete install from A to Z working first time! A large part of that result goes to you guys.

Take care,

 

[NASTY08IMPALA 5,000+ posts]

@Chromatic; how did the amp rack turn out?

 

[Chromatic]

[quote name='NASTY08IMPALA']@Chromatic; how did the amp rack turn out?[/QUOTE]


Well.. I got the materials do what you suggested.. lol. However,.. When I went to "mock it up" in the glovebox.. using your mount/rack would have essentially given me ZERO space left in the glove box to store/use.

So I had to really slim it down. This doesn't look like much.. But there's more to it than meets the eye:

This wood is 1/4" (I lowered it due to spacing concerns in glovebox)... And there is a hole in the middle of the glovebox that a tray sits in.. I removed this tray.. and this is where I feed my wires.

The 'hole" is a square'ish shape.. but has rounded edges.. So I cut the wood to an exact fit (I don't have great tools,.. So I was using a dremel for everything lol).

I matched carpet best I could.. and used several adhesives.. the first one didn't work, was more of a tack.

I then matched up screws (that was a pain) that would be LONG enough to go through the amp holes (which take 1/4" at least off the screw in the hole location).. Go through spacers.. and go into the 1/4" carpeted wood without coming out the other side.

So I cut, and carpeted the wood. Also painted the edges black to blend in (just carpeted top).. then bend/fold wouldn't fit in the small area lip I had to work with.

Then I put 1/4" spacers under the amp , under each of the 4 mounting holes.. Screwed it in.. And here's the amp on my "Rack" if you will. Looks very simple, but again.. if I didn't go this route I'd essentially lose all the storage space. This way.. I am taking another 1/4 inch or so carpeted piece and cutting to fit (at the angle above amp).. attaching it to top of amp.. and it will be the new "Base/bottom" of the glove box, netting me about half the space it originally had.

I have the PVC pipe, the spray paint.. the bolts, even some killer closed end gold heads I was going to thread on there.. But didn't get to use it.

I know this looks like it's a part of the car.. and simple -- But I think it turned out well and gives me a great deal of space to have in that glovebox.




So,.. I didn't lie to you -- lol.. Just when it came down to building,.. I quickly found out that I couldn't do it, unless I just wanted to dedicate the whole glove box storage to the amp alone.. and this car lacks other storage locations.. so I really need that space.

Hey, it's my first attempt at something like this.. I also have made it very easy to remove the amp to change settings, etc.. I got some industrial velcro.. and cut it exact to the lip,.. and on the bottom of the plywood.. So the amp isn't just sitting there loose.. it's solid in that industrial velcro. BUT,.. if I need to pull it out.. a little tugging will set it free from the velcro bond.. and when I'm done.. It goes right back on the velcro. May seem cheesy, but I think it's a smart idea.

 

[NASTY08IMPALA 5,000+ posts]

Well.. I got the materials do what you suggested.. lol. However,.. When I went to "mock it up" in the glovebox.. using your mount/rack would have essentially given me ZERO space left in the glove box to store/use.
So I had to really slim it down. This doesn't look like much.. But there's more to it than meets the eye:

This wood is 1/4" (I lowered it due to spacing concerns in glovebox)... And there is a hole in the middle of the glovebox that a tray sits in.. I removed this tray.. and this is where I feed my wires.

The 'hole" is a square'ish shape.. but has rounded edges.. So I cut the wood to an exact fit (I don't have great tools,.. So I was using a dremel for everything lol).

I matched carpet best I could.. and used several adhesives.. the first one didn't work, was more of a tack.

I then matched up screws (that was a pain) that would be LONG enough to go through the amp holes (which take 1/4" at least off the screw in the hole location).. Go through spacers.. and go into the 1/4" carpeted wood without coming out the other side.

So I cut, and carpeted the wood. Also painted the edges black to blend in (just carpeted top).. then bend/fold wouldn't fit in the small area lip I had to work with.

Then I put 1/4" spacers under the amp , under each of the 4 mounting holes.. Screwed it in.. And here's the amp on my "Rack" if you will. Looks very simple, but again.. if I didn't go this route I'd essentially lose all the storage space. This way.. I am taking another 1/4 inch or so carpeted piece and cutting to fit (at the angle above amp).. attaching it to top of amp.. and it will be the new "Base/bottom" of the glove box, netting me about half the space it originally had.

I have the PVC pipe, the spray paint.. the bolts, even some killer closed end gold heads I was going to thread on there.. But didn't get to use it.

I know this looks like it's a part of the car.. and simple -- But I think it turned out well and gives me a great deal of space to have in that glovebox.



So,.. I didn't lie to you -- lol.. Just when it came down to building,.. I quickly found out that I couldn't do it, unless I just wanted to dedicate the whole glove box storage to the amp alone.. and this car lacks other storage locations.. so I really need that space.

Hey, it's my first attempt at something like this.. I also have made it very easy to remove the amp to change settings, etc.. I got some industrial velcro.. and cut it exact to the lip,.. and on the bottom of the plywood.. So the amp isn't just sitting there loose.. it's solid in that industrial velcro. BUT,.. if I need to pull it out.. a little tugging will set it free from the velcro bond.. and when I'm done.. It goes right back on the velcro. May seem cheesy, but I think it's a smart idea. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Hey it looks clean you gota work with what the car gives you

 

[Chromatic]

Hey it looks clean you gota work with what the car gives you

Yup.. I'll show a pic of when I make the top piece to be the "shelf" as it were.. which will give me half of that glove box to use .. That's the best I could come up with ..

Compared to what you've seen (which is probably a lot).. Just how clean is that? I tried to make it "clean".. but it's my first install,.. so really zero experience here.. going by the seat of my pants on this stuff.

What I was going for was to make the car have no signs of having a "system" in it whatsoever.. I think I accomplished it, which is harder to do than I thought really.. Much easier to put amps in "convenient" locations out in the open for easy wiring.. Subs out in the trunk/hatch for easy access.. cutting holes in pillars with a 1" circular cutting bit and so on.

This is the car now.. see any signs of a "system" in it?



I could have taken a picture of the front doors.. but I did it up where nothing is seen there either.. Yet, still opened up the locations where the factory area was too small and too restrictive/muffled.

Serves a practical purpose of not advertising "Steal me".. and is sort of classy I think.. Not having a big ported box in the hatch.. amps and glowing lights out in the open, etc.

Now, no offense to those who SHOW off their stuff.. that's cool of course.. But I think "Stealth" as it were.. is less common than people wanting people to SEE their toys instead of just hearing them //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[NASTY08IMPALA 5,000+ posts]

Yup.. I'll show a pic of when I make the top piece to be the "shelf" as it were.. which will give me half of that glove box to use .. That's the best I could come up with ..
Compared to what you've seen (which is probably a lot).. Just how clean is that? I tried to make it "clean".. but it's my first install,.. so really zero experience here.. going by the seat of my pants on this stuff.

What I was going for was to make the car have no signs of having a "system" in it whatsoever.. I think I accomplished it, which is harder to do than I thought really.. Much easier to put amps in "convenient" locations out in the open for easy wiring.. Subs out in the trunk/hatch for easy access.. cutting holes in pillars with a 1" circular cutting bit and so on.

This is the car now.. see any signs of a "system" in it?



I could have taken a picture of the front doors.. but I did it up where nothing is seen there either.. Yet, still opened up the locations where the factory area was too small and too restrictive/muffled.

Serves a practical purpose of not advertising "Steal me".. and is sort of classy I think.. Not having a big ported box in the hatch.. amps and glowing lights out in the open, etc.

Now, no offense to those who SHOW off their stuff.. that's cool of course.. But I think "Stealth" as it were.. is less common than people wanting people to SEE their toys instead of just hearing them //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Yea it looks good and stealthy esp for ur first go at it ...just hard for me to hide a 26" amp

 

[Chromatic]

Yea it looks good and stealthy esp for ur first go at it ...just hard for me to hide a 26" amp

Hah.. Yeah,.. My original amp I was going for was 18" in length.. which would NOT fit in that glovebox area width wise.. maybe long ways if I removed the glove box..

Which is half the reason I went with a Class D amp.. the PPI amp dropped my size from 18" to 11".. much better. Plus the running cooler than an A/B.

But, I'm sure you have some insane 26" amp that puts out X thousands of watts. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[NASTY08IMPALA 5,000+ posts]

Hah.. Yeah,.. My original amp I was going for was 18" in length.. which would NOT fit in that glovebox area width wise.. maybe long ways if I removed the glove box..
Which is half the reason I went with a Class D amp.. the PPI amp dropped my size from 18" to 11".. much better. Plus the running cooler than an A/B.

But, I'm sure you have some insane 26" amp that puts out X thousands of watts. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Only 4300..and my ppi is 18" plus 2 batts hidden in my spare tire hole and about 150' of 1/0 wiring which u can only see 6" of ..i like big installs but they gota be clean

 

[n2audio 5,000+ posts]

To me,.. you can kill a speaker with a 1 watt amplifier that has unclean/high distortion much easier than you can kill a speaker rated at say 100watts rms putting a very clean 150watts RMS power on it.

If I am grossly off with any of these generalizations let me know.

I'm backtracking a ways here, but since you asked...

The high distortion 1 watt reference is not logical at all. The distortion itself isn't the issue. Power is the issue - which in many cases of speaker damage is due to clipping (a form of distortion). But an amp that can produce a maximum 1w signal before clipping can produce no more than 2w fully clipped. In terms of being damaged -- the waveform (clipped or otherwise distorted) doesn't effect the speaker. The only factor is the power being delivered and its ability to generate heat in the voice coil.

So there's no possible way for a 1w signal to blow a quality 100w rms speaker, neither will a 10w amp, or 20 or even 50. But when the actual power of the amp starts to approach the thermal power handling of the speaker the risk of speaker damage increases if you have an idiot cranking up the gain and/or bass boost and getting a lot of high volume clipping.

I remember several years back on carsound one of the techs was describing how they test speakers. They had a 15,000 x 2 commercial amp they liked to use because it was on a wheeled cart. They used it to test everything from Kw subs to 50w coaxials. The only time they blew speakers was during max power tests.

Regardless of the amt of power available - knowing how to use it is the key to getting a long life out of your speakers.

And a higher power amp ALWAYS presents more risk of speaker damage than a lower one.

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

No - x/o's aren't walls. They reduce frequencies above the set point gradually. At 105hz there would be almost no effect - certainly nothing audible.

That amp uses 12db/oct crossovers which works exactly how it sounds. With a LPF - going one octave above the set point gets you 12db less output. One octave above 100 is 200.

I could probably poke around and figure out two frequencies an a 1/2 power point (-3dB) to adjust to, but IMO - just trust your ears. Play a few different songs. Set it where you like it. One thing is for sure - you can't hear the display on your DMM.

And on the a/b vs d topic. For component speaker power -- I switched out a Zed Audio a/b from around '00 for a Lanzar (Korean I think) full range class D. I've been very happy with my class D - no negatives regarding sound quality.

 

[Chromatic]

@n2audio Thanks for the explanation,.. it is useful and interesting!

As for the crossover questions.. While I haven't done this.. I was thinking I could run my DMM on the speaker terminal and have laptop hooked to headunit through aux.. play tones with Audicity.. which can play any tone with a click essentially.. then when I see the voltage drop on the DMM (to some appreciable degree) (I don't know 1-5v+)? I'll know I've hit the beginning of the attenuation .. ie: The crossover number..

Example I play 95hz,96,97,98,99,100,101 and so on.. if I'm trying to set at 100 and have approximated the active amp Xover to 100 already but want to see just where it is (97? 103? etc..).. not that a few hz matters a great deal.

I'm tuning things by ear at this point.. I set the gains with the DMM.. the rest I've done by ear.. there is a great deal of tweaking to be done with the headunit after you set gains.. It's not just set gains and your ready to rock.. it sounds fairly bad with the EQ flat, etc when setting gains when you are done and plug the speakers into amp.

I've noticed from one recorded to another the bass output can vary damatically. I don't mean from like RAP to rock.. I mean.. for example last night I tested this.

I was playing Led Zeppelin Stairway (and would fastforward to when the drums kicked in..) played it off USB drive.. bass was MUCH less pronounced here.. Played it off CD and it was a bit better. Which is why I really am glad I decided to use the bass knob.. it's not going to be a "constant" setting that makes every song sound the same even in the same genre of music. Just depends on the recording, and to a lesser degree the input source I suppose. The USB drive measured 3.99v with no load.. So pretty close to the advertised 4v.

Ironically the CD was a bit lower than the USB.. I figured it would be the other way around.

A/B v D -- I'm sold on D if you need space and/or you need a cooler running amp.. which I did. Just do your homework and buy quality ,.. and you'll be happy with it.

I wonder as time goes on if A/B will turn into more of just an "oldschool elitist amp" and D will be the majority of amps sold.

 

[n2audio 5,000+ posts]

I wonder as time goes on if A/B will turn into more of just an "oldschool elitist amp" and D will be the majority of amps sold.

I can't think of a reason for that NOT to happen.

I think there will still be a market for a/b -- there will always be that group of people that believe they hear a difference, and maybe they do. Usually the same people spending thousands on speakers and amps. Thankfully I don't hear that well.

But size, weight, efficiency...there's just no reason not to at least TRY class d for full range.

 

[Chromatic]

I can't think of a reason for that NOT to happen.I think there will still be a market for a/b -- there will always be that group of people that believe they hear a difference, and maybe they do. Usually the same people spending thousands on speakers and amps. Thankfully I don't hear that well.

But size, weight, efficiency...there's just no reason not to at least TRY class d for full range.

First, I think this thread really turned out to be a very informative thread for me.. but also to go in the 'archives' of this forum and the internet at large.

And,.. I absolutely agree with you now on Class D. I can't hear anything but clean sound.. great power,.. from smaller form factor and cooler running. My ears are fairly particular with sound as well,.. so if a Class D doesn't bug me with SQ.. I don't think it will with "most" others. As you said though.. there will always be a niche that believe they hear a difference..and who am I to say they don't. Bottom line, you go with what you feel comfortable with.. it's your money, and you are the one listening to it.

A month ago I would have told you I'd never go to a 5 channel Class D amp.. now I'm a "convert" so to speak. Doubt I'll buy an A/B again.. I've never been one to get into audio competitions etc.. neat to go to and see the insane amount of money people have spent and the creative ways things are done.. but that's as far as I will ever get with that "scene" so to speak.

But yeah,.. there's no reason not to at least give a Class D full range amp a try. They are very reasonably priced. My PPI 5 Channel 900watt amp that's running Front components, rear German MB Quarts, and a 10" sub has plenty of room to push it..(and cost me a whopping $209) Gains are 50-60 percent for most of it. (I realize gains aren't volume knobs, but you get my point.)

My D amp is in a closed off non ventilated area.. and I put my hand on it after about 40 minutes of playing it hard today.. and it gets warm.. not put your hand on it HOT.. but fairly warm. Has an internal cooling fan,.. So I assume all that's normal temp. wise.