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

[bbeljefe]

I got it,.. honestly, understood all of it. I do know what a Sine wave looks like,.. and with my research and online classes I've learned the patterns of the wave.. How, let's just say on the headunit (I'll have the 12v from the battery (again a generalization.. I know voltages differ) -- The middle of the "rails" would be 6v,.. the bottom of the sine wave 0v (ground), and the top crest +12v. -- So take that middle of the rail in the headunit at 6volts.. and apply 6vp/sqrt(2) = 4.2 Volts, thus this would be the 4v Signal coming from the pre-out(s) (Again, I know this voltage isn't going to be this perfect theoretical 4.2v) -- It goes into the Amp which then , well, amplify's this voltage and so on.
Now, if DMM's were as easy as I make it sound to dial in a system,.. then there wouldn't be O-scopes and other equipment to adjust a system from the amp to EQ's , crossovers, et al.

That said,.. If I buy an amp with some headroom. Let's say I need 100watts RMS (as the speaker is rated (and it's a quality speaker) ).. and the amp I purchase is a quality amp that can push 150watts on that channel,.. That leaves some decent headroom (and the way I see it.. a little room for error, given I'll be dialing in with a DMM). So in this example,.. if I set this headunit AVH-P4100DVD - In-Dash Double-DIN DVD Multimedia AV Receiver with 7" Widescreen Display | Pioneer Electronics USA Which is the headunit I have installed to 75% (some say go 80-90%.. most say 75%).. volume,.. set bass/treble to 0/zero and I suppose set the Parabolic EQ flat? -- Then have the amp gain on zero to start. Put in 1khz Sine wave tone off a CD (or usb stick) that plays for 5 minutes straight.. and go to the amp positive terminal, stick the DMM on the positive terminal,.. and slowly move up the gain for this channel(s) until my DMM reads 20v on the nose,.. And I'm obviously listening at the same time,.. and no distortion is audible,.. Then perhaps I put in a clean song.. (I know music //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif ) -- and listen closely to it,.. That should be a reasonably safe way to dial in the amp given I don't have the O-scope or other such tools, no?

Then for the sub I'll repeat process, but play a 40hz sine wave .. And adjust the sub channel(s) gain for voltage for 4ohms at Subs RMS rating -- Let's just use 100watts RMS on an 8" sub for ease of math, and coincidentally it would be the same voltage rating as the front speaker(s),.. to 20.00v on the DMM,.

That's the only way I know how to do it without several hundred to several thousand dollar equipment that would obviously be foolish for me to purchase. I'd love to have a scope where I can watch the Wave in real time.. to ensure the peaks and troughs don't flatten out (clip).

I've heard people tell me that going to the "trouble" of using a DMM and doing what I just described as being a waste of time.. to set everything where it distorts then back down just slightly and you are done.

In my opinion,.. spending 10 minutes or so adjusting voltage playing a tone that's right for the speaker type (be it a mid/high/ or sub) and having a DMM on the positive terminal and taking my time adjusting the gain from zero up to voltage is not a waste of time,.. nor difficult. Why chance it? Why not dial it in the best you can with the tools and knowledge you have?

Aside from having the O-scope or other tools needed to really see what is going on,.. I am left with little choice other than to bring the car to a shop that does have these tools (which I'm willing to bet quite a few don't even have them.. and adjust by ear, or at best with a DMM.. but that's a guess) and tell them, I need my amp dialed in please.. and pay them $100 or whatever fee they would charge.

I agree with you! I understand, granted at an early stage of learning these principles, the dynamics going on and why using just voltage readings doesn't guarantee me "Safety" or even being at the right gain for my needs -- But, am I wrong in the broad generalization that purchasing a/an Quality amp with say 50% headroom (or more) over the RMS rating of the Quality speakers gives me a better chance of dialing it in using the DMM without introducing distortion and/or clipping into the equation?

You obviously know the science of this quite well, and are used to doing it the proper/best way possible -- It shows by your responses, and you being the OWNER of Audio Anarchy //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif -- However, I am trying to do things "right" the best way I can with what I have available to me. I also know just because X percent of people dial in their amp gains by ear, or at best with a DMM (some maybe not even really knowing what they are doing or why).. doesn't mean that because they do it this way that so can I, and be trouble free.

I just feel fairly confident in buying a quality amp that has SOME headroom in it,.. with quality components and proper passive crossovers, and a headunit that I linked above that from what I've read in it's specs puts out a great, clean, 4v signal (It's not the best in the world.. but it's certainly mid range I would say) -- That dialing it in with the DMM with the tones I mentioned should produce a safe environment for my setup.

If not, let me know. This is a bit odd, cause I am not overthinking this part -- I am solid and confident in purchasing the components as mentioned and using the method I explained,.. and you are informing me.. "Hey not so fast.. !" //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

You are 'somewhat' close to me.. as I am in Birmingham, AL -- but it's still a 6+ hour drive. If you were say 2 hours away, I'd say screw all this and come to your place and let you help me pick out everything and have your employees install it all. Unfortunately you are nearly 7 hours away, so best I can do is take your advice.

Thanks for all the help,

I'm not telling you not to use a DMM... it's your system and you can use a yard stick to set your gains if you like. I'm just sharing information to the best of my knowledge in the hopes that people are able to learn as much as possible about this hobby/obsession some of us have. ;-)

And I'm also not trying to send you to a store that can't do any better than you can (and trust me, you have a better understanding of this than a plurality of installers), nor am I asking you to drive to my store.

That said, the DMM method is not reliable. ← Dead horse, I know. But that's not to say it can't or shouldn't be used in the absence of the proper equipment, because it will certainly get you closer than the by ear method. But again, if there is any distortion in the system, it won't detect it, regardless of how far below the rails you set the gain... and a clipped signal is not good even when it isn't on the rails.

With all that said, here's what I would do if I were forced to use a DMM for gain setting. First, I'd try to find out if someone else has tested my head unit model for clipping. A google query works well. If I found that information, that's where I'd set it and if not, Id set it at ~80% with all tonal controls and eqs flat, and with no crossovers set. Also, no loudness contours or bass boost circuits on an I would find out if my subwoofer level control had a boost circuit or if, when turned all the way up, it was at 0dB. And then I'd set it at whatever the 0dB point is.

I'd go to D'Amore Engineering's website and download the DD-1 CD test tracks (free), most importantly tracks 1 & 2 which are 40Hz @ 0dB and 1kHz @ 0dB. I'd use those tracks because they are known to be clean. Then I'd set the amplifier crossovers, bass boosts, et al just like I did the head unit's and I would disconnect all speakers.

And then, of course, I'd go about setting the gain to max output less one or two volts. That would be as close to accurate as I could get while still taking advantage of my amplifiers' potential.

Just an afterthought or two... when you hear distortion, it has been a problem for a while. This is why the "by ear" method is not advisable. All of the Pioneer head unit's I've tested have clipped at 48 or 9 on the volume scale or, ~80% but, I've not tested yours. Lastly, if you're a member of Steve Meade's forum, there is a thread that has a tool map of sorts which shows various people all over the world who own oscopes, distortion detectors and other test equipment. I know there are some of those people in Alabama and a lot of them will help you for gas money, beer or ~$25.00. Some will help for free.

 

[Chromatic]

I'm not telling you not to use a DMM... it's your system and you can use a yard stick to set your gains if you like. I'm just sharing information to the best of my knowledge in the hopes that people are able to learn as much as possible about this hobby/obsession some of us have. ;-)

lol.. I'm just trying to use what I have available. I have a few DMM's.. I use them all the time for work. I'll leave the yardstick for tuning the parabolic EQ (kidding).

And I'm also not trying to send you to a store that can't do any better than you can (and trust me, you have a better understanding of this than a plurality of installers), nor am I asking you to drive to my store.

Thanks.. means a lot.. considering I've only been researching this for a 5-10 days. And,.. I just guessed that the other shops would probably not be using the O-scopes etc.. and some not even DMM's.. but , well, ya know.. that's the way it goes in the world. Anyone Joe Schmoe can setup shop, and worse hire people who have little to no knowledge for minimum wage. Then charge you $100 an hour for their $8 an hour work.

That said, the DMM method is not reliable. ← Dead horse, I know. But that's not to say it can't or shouldn't be used in the absence of the proper equipment, because it will certainly get you closer than the by ear method. But again, if there is any distortion in the system, it won't detect it, regardless of how far below the rails you set the gain... and a clipped signal is not good even when it isn't on the rails.

But, we both know it's the best I can do... and it isn't justifiable to purchase equipment that cost as much as the "system" I will be installing or more to tune a single amp. I'm going to have to take that risk,.. but perhaps I can search around and tune it myself,.. then if I can find someone with the equipment get it checked and dialed in a little better by someone who knows what they are doing with the right equip.

With all that said, here's what I would do if I were forced to use a DMM for gain setting. First, I'd try to find out if someone else has tested my head unit model for clipping. A google query works well. If I found that information, that's where I'd set it and if not, Id set it at ~80% with all tonal controls and eqs flat, and with no crossovers set. Also, no loudness contours or bass boost circuits on an I would find out if my subwoofer level control had a boost circuit or if, when turned all the way up, it was at 0dB. And then I'd set it at whatever the 0dB point is.

The amp I'm leaning toward has a bass "knob" (may be silly and impractical.. or even dangerous.. I don't know.. but it's there). In particular the Kenwood that I found on this forum looks absolutely perfect, it feel intuitively RIGHT to me.. I hope it's of high enough quality and doesn't get shot down by others here.

But good advice on googling others with this Pioneer AVH-P4100DVD headunit.. It's a really popular unit, especially in the 350Z due to the way it fits in the factory slot. So maybe I will find those values for clipping. Otherwise,.. 80% it is.

Question: Setting EQ's to flat.. Is that all levels to zero on the EQ itself,.. or just flat as in all EQ settings across the range even?

I'd go to D'Amore Engineering's website and download the DD-1 CD test tracks (free), most importantly tracks 1 & 2 which are 40Hz @ 0dB and 1kHz @ 0dB. I'd use those tracks because they are known to be clean. Then I'd set the amplifier crossovers, bass boosts, et al just like I did the head unit's and I would disconnect all speakers.

That's where I got the tracks I have. So good deal,.. coming from you I know they are solid. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Ok now you say after I do the test tracks.. I'd then disconnect the speakers and set the amplifier crossovers, bass boosts, and other such settings? Do you mind explaining that a little more for me? IE: Reason for disconnecting speakers before setting those values? And is it just for "Safety" .. set values (Ie: Highpass on the fronts on the amp to say 100 or 120hz cutoff,. ).. (Lowpass for the single sub on the bridged 3/4 channel to something like what.. 80hz and below? Or should I match frequencies .. say 100hz and up for fronts (which will be separated again by passive crossover to separate the upper range for tweeter and lower range for 6.5 woofer), and then set the sub at 100Hz and down (so there isn't a 20hz gap missed?).

And then, of course, I'd go about setting the gain to max output less one or two volts. That would be as close to accurate as I could get while still taking advantage of my amplifiers' potential.

Ok interesting.. So basically I'll be dialing in 20volts.. Then to be safe,.. drop the gain down a touch till it hits 18-19v ?

Just an afterthought or two... when you hear distortion, it has been a problem for a while. This is why the "by ear" method is not advisable. All of the Pioneer head unit's I've tested have clipped at 48 or 9 on the volume scale or, ~80% but, I've not tested yours. Lastly, if you're a member of Steve Meade's forum, there is a thread that has a tool map of sorts which shows various people all over the world who own oscopes, distortion detectors and other test equipment. I know there are some of those people in Alabama and a lot of them will help you for gas money, beer or ~$25.00. Some will help for free.

I am not a member on his forum, But I"ll certainly look into it. I'll dial it in myself,.. I'm pretty confident if I set it up at 80% volume, everything set to zero/flat -- and run a volt or two under on the DMM, I'm probably in the safe range. Further I'm not going to be cranking this up anyways. It is my understanding clipping occurs as you increase volume on the headunit which increases the amplifier voltage and thus pushes the rails to potential flattening of the crest and troughs,.. so the lower the volumes the less potential for such clipping. That last statement I just typed sounded incredibly "Captain Obvious" .. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Appreciate all your sage advice,

 

[bbeljefe]

lol.. I'm just trying to use what I have available. I have a few DMM's.. I use them all the time for work. I'll leave the yardstick for tuning the parabolic EQ (kidding).


Thanks.. means a lot.. considering I've only been researching this for a 5-10 days. And,.. I just guessed that the other shops would probably not be using the O-scopes etc.. and some not even DMM's.. but , well, ya know.. that's the way it goes in the world. Anyone Joe Schmoe can setup shop, and worse hire people who have little to no knowledge for minimum wage. Then charge you $100 an hour for their $8 an hour work.

But, we both know it's the best I can do... and it isn't justifiable to purchase equipment that cost as much as the "system" I will be installing or more to tune a single amp. I'm going to have to take that risk,.. but perhaps I can search around and tune it myself,.. then if I can find someone with the equipment get it checked and dialed in a little better by someone who knows what they are doing with the right equip.

The amp I'm leaning toward has a bass "knob" (may be silly and impractical.. or even dangerous.. I don't know.. but it's there). In particular the Kenwood that I found on this forum looks absolutely perfect, it feel intuitively RIGHT to me.. I hope it's of high enough quality and doesn't get shot down by others here.

But good advice on googling others with this Pioneer AVH-P4100DVD headunit.. It's a really popular unit, especially in the 350Z due to the way it fits in the factory slot. So maybe I will find those values for clipping. Otherwise,.. 80% it is.

Question: Setting EQ's to flat.. Is that all levels to zero on the EQ itself,.. or just flat as in all EQ settings across the range even?

That's where I got the tracks I have. So good deal,.. coming from you I know they are solid. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Ok now you say after I do the test tracks.. I'd then disconnect the speakers and set the amplifier crossovers, bass boosts, and other such settings? Do you mind explaining that a little more for me? IE: Reason for disconnecting speakers before setting those values? And is it just for "Safety" .. set values (Ie: Highpass on the fronts on the amp to say 100 or 120hz cutoff,. ).. (Lowpass for the single sub on the bridged 3/4 channel to something like what.. 80hz and below? Or should I match frequencies .. say 100hz and up for fronts (which will be separated again by passive crossover to separate the upper range for tweeter and lower range for 6.5 woofer), and then set the sub at 100Hz and down (so there isn't a 20hz gap missed?).

Ok interesting.. So basically I'll be dialing in 20volts.. Then to be safe,.. drop the gain down a touch till it hits 18-19v ?

I am not a member on his forum, But I"ll certainly look into it. I'll dial it in myself,.. I'm pretty confident if I set it up at 80% volume, everything set to zero/flat -- and run a volt or two under on the DMM, I'm probably in the safe range. Further I'm not going to be cranking this up anyways. It is my understanding clipping occurs as you increase volume on the headunit which increases the amplifier voltage and thus pushes the rails to potential flattening of the crest and troughs,.. so the lower the volumes the less potential for such clipping. That last statement I just typed sounded incredibly "Captain Obvious" .. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Appreciate all your sage advice,

Yes, set the eq points to zero. And the part about the crossovers was obviously not well worded. What I mean it to turn off the crossovers but since a lot of amps don't allow that, I set them as high as possible for low pass filters and as low as possible for high pass filters. Also, that's not really important for DMM setting, because you can't see distortion regardless of what frequency it's at. But the point is that you don't want to cut any frequencies when looking for distortion because there could be some noise on the line that could be attenuated or completely hidden with a crossover turned on. In any event, disregard that part.

The reason for disconnecting the speakers during setting is that you don't want any load on the circuit when you're checking output. You want the amp to be sending a true voltage signal and that might not be the case when it's under a load. Not to mention, a 1kHz tone played at high volume for any length of time is enough to drive even the most sober man to drinking, lol.

And yeah, if 20 volts is the amp's maximum rms, then 18 volts would be peachy. If you have a bass knob, set gains with it turned all the way up and if you like it, use it. I use them and they don't create problems.

As for your last comment, you're technically correct. Unless you have a clipped source. But with a clean source low volumes low volumes can't cause the amp to clip so long as the voltage is equal to or lower than the gain setting.

In simple terms.. The gain and volume knobs are essentially the same things. And so is the bass knob. It's just that they're designed for different purposes.

And you're welcome. I appreciate the kind words.

 

[So Low iT Hz]

I have to chime in here on the class differences, mainly because its important to understand how they work to really know what to look for or how to properly implement them. And on a side note class D is technically NOT an amplifier, as only pure analog circuits can be called amplifiers, but thats too far gone at this point and basically just an extra tidbit for your brain.

This will be very simplified, but enough for you to understand the key points. First off is class A. You send in a signal, which is routed through an amplification circuit, out comes a bigger signal. Simple, and predictable ("root two"). Efficiency is lower in comparison because the FETs are more or less wide open, like a bucket of water, waiting for a signal to get "poured" into it.

Class D is waaaaaay different, until the very last step. First thing that happens is the signal gets chopped into an infinite number of little "chunks", individually augmented, and reconstructed to the new signal, and sent through to the output. The problem that arised a decade ago with class D was that the clock speed of the processor that deconstructed and reconstructed the waveform was below the higher end of the audible frequency range, IMO 25 kHz. This meant that higher frequency notes were impossible to "amplify" due to the limitations of the processing. Thus class D was reserved for low frequency reproduction, such as bass amplifiers. Nowadays, the full range class D is much improved, as the processing is more powerful. As stated before, the output of a class D is very similar to an analog amplifier, so similar that you probably wouldnt be able to tell without the use of a tool of some kind. There are more phase issues between the output voltage and current, as the traditional analog circuits have basic electrical laws optimizing these conditions. Class D's do not.

Brands that have made a name for themselves with high power full range digital amplifiers are becoming increasingly good at producing quality reproduction with higher efficiency in a smaller and smaller footprint. Stetsom and Soundigital come to mind there. I ran a Stetsom 2k for my highs and omg itd make your ears bleed from a block away. But when it comes down to it, you cant go wrong with most "cheap" analog amplifiers, so long as you buy like four of them to get the output that they rate for one lol, but the "cheap" full range digital amps out there are typically garbage. I had a choice between the digital four channel Sundown amps and the 100.4 and I opted for two 100.4's. And I cant say enough about how good they sound. Though I do miss my Stetsom...

 

[Chromatic]

Thanks for the advice/wisdom both of you!

Here's the thing. I really like this amp,.. I"ll admit, the Kenwood brand,. given I ran a system 5 years pounding on 2 , 100watt Kenwood A/B amps and 1 Kenwood 300watt A/B amps (2 of them were refurbished.. (at that time my friends older brother worked at the audio shop.. so made sure I was taken care of on the install.. don't have such a connection these days unfortunately).

But.. All I remember was those Kenwood amps were solid,.. never a problem.. ever. No clipping, no shutting off in 105degree heat here.. and I wasn't the gentlest on that system. So I assume it was probably dialed in properly,.. disallowing me to "break it" in a manner of speaking. I , at that time, just thought Gains were basically volume (or power knobs) on the amps.. could only set them with a flat head screw driver.. I never touched them. Kenwood in home audio has also been good to me,.. so you get it.

So this: Kenwood XR-4S eXcelon Four Channel Amp Digital Car Amplifier 4-3-2 Ch Switchable (Link)

Kenwood - XR-4S

Seems to be a CEA-2006 hit.. -- But this amp seems like a winner to me,.. It is perfect for my application,.. gives me headroom.. 20watts per speaker on the two fronts (As this amp runs 120watts @ 4 ohms RMS).. and 150 watts headroom on the sub (amp bridges to 300watts @4ohms RMS). I'm really just about locked into going 8" sub in sealed enclosure instead of 10" sub.

Tell me now, or forever hold your peace //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif -- if that Kenwood amp is not a decent midrange amp?

I probably won't go the refurbished route with it,.. though it's tempting,.. but it runs $299 (maybe cheaper if I shop).

 

[MXcarAudio]

Thanks for the advice/wisdom both of you!
Here's the thing. I really like this amp,.. I"ll admit, the Kenwood brand,. given I ran a system 5 years pounding on 2 , 100watt Kenwood A/B amps and 1 Kenwood 300watt A/B amps (2 of them were refurbished.. (at that time my friends older brother worked at the audio shop.. so made sure I was taken care of on the install.. don't have such a connection these days unfortunately).

But.. All I remember was those Kenwood amps were solid,.. never a problem.. ever. No clipping, no shutting off in 105degree heat here.. and I wasn't the gentlest on that system. So I assume it was probably dialed in properly,.. disallowing me to "break it" in a manner of speaking. I , at that time, just thought Gains were basically volume (or power knobs) on the amps.. could only set them with a flat head screw driver.. I never touched them. Kenwood in home audio has also been good to me,.. so you get it.

So this: Kenwood XR-4S eXcelon Four Channel Amp Digital Car Amplifier 4-3-2 Ch Switchable (Link)

Kenwood - XR-4S

Seems to be a CEA-2006 hit.. -- But this amp seems like a winner to me,.. It is perfect for my application,.. gives me headroom.. 20watts per speaker on the two fronts (As this amp runs 120watts @ 4 ohms RMS).. and 150 watts headroom on the sub (amp bridges to 300watts @4ohms RMS). I'm really just about locked into going 8" sub in sealed enclosure instead of 10" sub.

Tell me now, or forever hold your peace //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif -- if that Kenwood amp is not a decent midrange amp?

I probably won't go the refurbished route with it,.. though it's tempting,.. but it runs $299 (maybe cheaper if I shop).

That Kenwood is a nice amp but an older model the crossover on that is very nice since it can do band pass but like i said older amp, look into the PPI 900.4 these in my opinion is a better amp and the PPI can also do the band pass crossover. Not that many 4 channel amps can do bandpass crossover

 

[Chromatic]

That Kenwood is a nice amp but an older model the crossover on that is very nice since it can do band pass but like i said older amp, look into the PPI 900.4 these in my opinion is a better amp and the PPI can also do the band pass crossover. Not that many 4 channel amps can do bandpass crossover

I like that PPI amp.. it's cheaper new.. It's class D (I like the new tech).. It's small enough to fit,.. And rates 145watts x 4 at 14.4 volts,.. but at 12v is 100watts v 4 (IIRC).. which of these two ratings is more likely to be accurate? I know what the car runs with alternator going turned on.. which is upper 14 volt range. Either way, 100 or 145 is enough for my application, both on the fronts, and the sub (I only need 150watts for the sub). BUT, the more headroom I have, imo, the better. I want to set the gains as low as is possible while still providing proper power. So 145 on say 100watt speakers will be nice on the gains,.. and 150watts on bridged channel 3/4 out of 450watts (at 14.4v) possible will really let me keep that gain low.

Anyone else prefer that PPI over the Kenwood eXcelon amp that is $299 ? Kenwood - XR-4S

I'm about 99% set on an 8" sub,.. but could at the last second move to 10". I sort of would like a bass knob that many of the newer amps have (i know it's gimmicky).. but ONLY because I'd like to be able to have an analog control that's handy to make on the fly adjustment to the bass. One of my bigger concerns is even with an 8" JL sub at 150watts.. it will be too much bass for what I'm after,.. and won't be incredibly easy to adjust downwards (maybe my Pioneer AVH-P4100DVD amp with it's 6 band parametric EQ built in, built in high pass and low pass filters,.. and direct Subwoofer control and levels (From Sub RCA pre-outs) may be enough to adjust the sub by itself) ?? Here's the headunit I have in the car: Pioneer AVH-P4100DVD DVD receiver at Crutchfield.com

But, obviously.. a bass knob is NOT going to rule what amp I purchase,..

So,.. with the PPI amp you recommend (which I like very much),.. and an 8" JL Audio sub in a sealed enclosure, with $200-300 set of 6.5" components with likely a 1" tweeter running at ~100 watts RMS per speaker -- Will I be able to tune it in bass to mid/high's to my liking? IE: If I feel the bass is too much after I set it up,.. I can literally tune the sub down from being barely audible up to ridiculous punch (not what I'm after).

I'm thinking yes.. between the amp with it's features + the Headunit I'm using which is feature rich with separate RCA Sub pre-out that is very adjustable even on the touch screen of the Headunit that too much bass from the sub shouldn't be an issue for me.

I understand crossovers.. but just refreshen me on this particular PPI 900.4 amp and it's bandpass crossover function(s).. what exactly will I be able to fine tune/control that the Kenwood for example wouldn't allow?

I may go active a few months down the road,.. but I'm starting passive, and it's going to be a 2.1 system in a 2 seater sports car (350Z).. I'm looking for a better sound than the factory clarion 10watt speakers with blown tweeters.. Pretty much anything I put in this car is going to blow me away,.. So you know. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Thanks

 

[treesive 10+ year member]

I have used some of the best class a/b,d,and g/h amps on the market. After saying that I do not run class d on my high's. This might not be so much the class d amps but they obviously have something different that makes them more prone to noise, whine, etc. I had the same problems with my hd600/4, hifi 6150, and the PPI900/4 which was the noticeable alt whine coming through the speakers. This to me since I am more SQ geared is a pure no no. At first I thought it was the legendary pico in my headunit even though I did the rca ground etc to the head when I bought it. I was pretty much set on breaking it open to solder over it when I was in the process of changing my amps out. I put my se4200 back in (class g/h) instead of my hd and took it around the block a couple times to determine if I liked where my settings were. It caught me off guard when I noticed zero whine from the speakers. I tried it again with my usa-442, zapco z150.4, and my honey elite.4. None of them sent that whine through to the speakers. Now I don't know enough about the inner workings of amps but something with my systems setup will not allow me to run full range class d. Sound wise I do think that class d is getting close enough by the quality brands to not be noticeably worse in sound than other classes. I just figured that it was important to tell you this story as something in the design differences allows this to happen in my setup.

 

[Chromatic]

Thanks treesive for your story. I was all set to order the class D 4 channel amp tomorrow,.. now it's a little concerning that you say you get noise/whine from them. I'm going to have to go with the rest of the people who use them, and tend to think it was an issue with your particular setup somewhere. If decent class D amps all tended to have noise/whine the reviews on them would be horrible. Thanks for the heads up,.. and if I end up with a noise problem I can come back and tell you that you told me so! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

But, with the space I'm working with.. putting the amp in a closed non ventilated area.. A 4-channel class D amp is the only thing that makes sense for my application now. A/B barely fits (some don't).. and they will run hotter,.. and adjusting them once mounted would be next to impossible. So I'm going to have to take the chance. I'm either going with the Kenwood eXcelon 120x4, or the PPI 900.4 (I think it's called) which is about the same.. a little more powerful at 14.4v. Both good brands,.. I don't think either have the "bass knob" that I'd like to have to mount by the parking brake in an empty switch slot to adjust on the fly.. but that's life.

This a typical widespread issue you guys with say a PPI Class D amp? That I will probably get noise/whine using it?

I'm not doubting you at all treesive,.. I totally believe you got whine in your setup with multiple non A/B amps -- and something about the A/B design kept that from occurring.

Thanks

 

[treesive 10+ year member]

I agree that it is something in my system but there is nothing complex about mine so I am guessing it is rather easy to have it happen. I just wanted to make sure I passed it along incase it happens so you aren't blindly surprised by it.

 

[mat3833 10+ year member]

i didnt read any of the rest of this thread, just the title and part of the first post. so sorry if this doesnt help you at all.

ive ran class A/B, Class A, and Class D amps. all three on my front stage and ab/d on my subs. the information that follows is strictly MY opinion based on MY listening experience:

on sub duty there was little difference between good quality D and A/B amps. the A/B had a slightly different sound, but im not sure how to explain it other than "better". currently im running a Class D substage amp, getting high powered A/B amps for sub duty requires a TON of space, over 24" long usually, and my install had space limits that i had to stick too.

on stage duty the difference was pretty large when going from a mid level(old school) A/B to a class D(Zed Mikro IV) the class D actually sounds a TON better than the mid level Class A/B. but when comparing the D to a high end Class A/B there was virtually no difference. some things sounded different on each amp, but overall the sound was great from either. im running class D up front as well.

if i had tons of space, electrical that could handle 300a of current draw, and i was rich, i would run Class A/B completley. as it stands, im more than happy with my amps. amps are one of the last things that contribute to a nice sounding system. Quality recordings, Source, Drivers AND install, all play a larger part than an amp.

Matt

 

[Chromatic]

i didnt read any of the rest of this thread, just the title and part of the first post. so sorry if this doesnt help you at all.

This helps me more than you know!

ive ran class A/B, Class A, and Class D amps.

on sub duty there was little difference between good quality D and A/B amps. the A/B had a slightly different sound, but im not sure how to explain it other than "better". currently im running a Class D substage amp, getting high powered A/B amps for sub duty requires a TON of space, over 24" long usually, and my install had space limits that i had to stick too.

I'm working with limited space as well. I have to fit the amp in a 17 and 3/4" wide by 8" deep area. So the Class A/B I was originally going for was REALLY tight.. and wiring and then adjusting it after mounted was not going to be an easy task. When I learned more about the Class D and how they've improved over the years -- It really opened my eyes. The place I'm putting my amp is going to be closed, not open.. relatively small space,.. so I need a small dimension amp and one that can run cooler due to lack of active airflow. Class D does both of these things.

on stage duty the difference was pretty large when going from a mid level(old school) A/B to a class D(Zed Mikro IV) the class D actually sounds a TON better than the mid level Class A/B. but when comparing the D to a high end Class A/B there was virtually no difference. some things sounded different on each amp, but overall the sound was great from either. im running class D up front as well.

This is exactly what I wanted and needed to hear. I'm ordering tomorrow so stuff ships out Monday,. and Class D it will be.. Most likely it will be the PPI 900.4 Class D 4 channel amp. Since people seem to prefer the PPI brand over Kenwood here,.. and I'm trusting everyone who obviously have more experience than I. (My last system was in 2000) //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Things have changed a bit.

if i had tons of space, electrical that could handle 300a of current draw, and i was rich, i would run Class A/B completley. as it stands, im more than happy with my amps. amps are one of the last things that contribute to a nice sounding system. Quality recordings, Source, Drivers AND install, all play a larger part than an amp.

Matt

Well.. I'd do the same and I'd run a little different package of speakers as well -- But mine is more limited by my goals of sound (I just want an improvement over the two 6.5" 10 watt factory speakers I have.. and a little bass) -- So I'm on a budget.. budget went from $350 to $1000. With what I've been recommended and shopped around for online,.. I can get everything plus wiring for $700-750. Since I'm 100 percent installing myself now,.. that's the final price. As I wrote,.. I gave the two local shops to do something for me for a grand.. and they could only go $1500 for a 3 speaker install,.. so I'm now jumping in my first install and spending half that for better components.

Thanks for the vote of confidence on the amps!

 

[Chromatic]

I'm settling in on the PPI amps.

But I ran across the PPI.5 -- Which is similar in price to the PPI.4.

PPI.5 (5channel, 70watts RMS x 4 (4ohms) + 5th channel 440watts RMS for sub)

Precision Power PPI P900.5 (p9005) 5-Channel Phantom Car Amplifier

The power is lower, but it's 5 channel,.. which gives me an option to use my MB Quart 6.5" Coaxials that are 70watt RMS in the rear factory 6.5" slots -- to make this a front 6.5" component with 1" tweeters with the JBL MS-62C 80watt RMS speakers JBL MS-62C (MS62C) 6-1/2" 2-Way MS Component Car Speakers System AND have my (already owned) stored MB Quart (German made) QM-160 KX 6.5" Coaxial 6.5" (with 1" coaxial tweeters) that run 70watts RMS in the rears...

My 90's German Made MB Quarts:



For a total of 4 , 6.5" mids, and two component 1" tweeters up front, and 1" tweeters on the MB Quarts across the mid cone in the rears,.. Plus the single sub in the custom box.

It's just an idea,.. and the PPI 900.5 has a bass knob I'd mount up in an empty switch spot by the shiftknob/parking brake to be able to adjust Sub output on the fly?

So,.. it's the same brand, similar amp,.. Class D,.. similar price -- Less wattage for components but VERY close to RMS ratings of fronts, and the exact RMS rating of the rear MB Quarts.

Would I be foolish not to go ahead and grab the PPI 900.5 and run these MB Quarts I already have in my closet in the rears? Or would it still be better to get the PPI 900.4 and have more headroom on the amp for the just front components + single sub?

Just a last minute idea as I didn't know of this amp till it popped up a minute ago.

Thanks

 

[MXcarAudio]

go for the 5 channel, u dont need that many watts to get loud on mids specially mid range, it does not react the same as a sub that you need a lot of wattage to get loud. I'll say it again I think your over thinking this set up , dont worry about the whine you dot have powerful amps that can introduce whine, and from your postings i dont think your a guy that cranks his system up. just make sure you have everything grounded right like grind the paint out and ground to the metal chassis, this is where most of the whine comes from

 

[Chromatic]

go for the 5 channel, u dont need that many watts to get loud on mids specially mid range, it does not react the same as a sub that you need a lot of wattage to get loud. I'll say it again I think your over thinking this set up , dont worry about the whine you dot have powerful amps that can introduce whine, and from your postings i dont think your a guy that cranks his system up. just make sure you have everything grounded right like grind the paint out and ground to the metal chassis, this is where most of the whine comes from

I'll say this again -- I know I think a lot.. I am a systems engineer if that tells you anything (computers). It's how I've always been, how I will always be. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I've already ordered, sunday, all the speakers, amps, custom enclosure, sound deadening, shrink tubing, etc etc.. So it was done before you posted, but thanks for the affirmation. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

People say I'm an idiot for putting rear speakers in the rear speaker slots in this 350Z -- They say that it will make the sound worse. (This is on a 350Z forum).. But I'm going to do it anyways due to the 5 channel amp, and the fact I have $500 (in the late 90's) German made MB Quart coaxials to put back there.. So they are going in. I'll dial them up first.. then dial them down and down to see how the sound changes, and then cut them off to see how that sounds. I still think they will add something to the overall sound for the positive, even if I have to dial the rears back to 20%. If they end up really making it all sound worse.. I guess I'll put them up for sale, someone will want them, they are phenomenal coaxials, best sounding coaxials I've ever heard to "my" ears.

As far as whine.. I didn't think that was a factor of wattage but more a grounding issue or noise being introduced from inputs, etc. I'm not worried about whine.. And I'm grounding to a factory ground point, already located one.. and then putting a lock nut and bolt on it. No single screw into painted sheetmetal crap for me //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

As I overthink you say.. I also Over-engineer. Running oversize wiring,.. and instead of crimping wires together,.. I'm going to tin and solder everything.. and use my butane torch to solder the power and ground wire connections. Takes a few seconds.. why not?

If I really wanted to over do this.. I'd have bought 0 gauge power and ground wires etc.. But running a 900watt amp and 5 speakers.. I think the 4 gauge kit will more than do for 900watts RMS.

Thanks for the tip on the ground though.. It's a great one that I'm sure a ton of people don't consider.

You have people like me on one end of the spectrum who "over-think".. and then people who don't do any research and run 20 gauge speaker wire to power their amp, and ground it to something silly with a single screw that comes loose in a few months, that turn their amp gains to max.. and string together random pieces of wire they can find of different gauges for their speaker runs. I saw one guys setup who had 8" pieces of wire all twisted together on like 15 foot runs to his speakers, and ran his subs out of two 5 gallon buckets rofl. Nuts what some people do.

Appreciate the advice.