Class a/b vs class d....
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Silver Member Username: GoonPost Number: 296 Registered: Feb-05 | I read a little on class a/b and class d amps and I understand how they work. But I don't have much experience in this field, so I was wondering how much of a difference there is between the two in terms of performance, SQ, ect ect. The amp will be powering two 12" perfects(if this helps at all). thanks guys. |
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Gold Member Username: CarguyPost Number: 4200 Registered: Nov-04 | Have you been to bcae1.com? I think he has an article on classes. Class AB will offer the best possible SQ. However, Zapco makes class D that will sound just as good. It'll be very hard to tell by human ear. Now if you compared cheaper class D with AB, then maybe in certain circumstances, you might notice a slight drop, but again, it'll be very hard. The main advantage of class D is efficiency. It'll use less power to produce same amount of output. In general, use class D, unless you know exactly what you're doing/want to accomplish. |
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Silver Member Username: GoonPost Number: 299 Registered: Feb-05 | thanks again man. |
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Silver Member Username: GoonPost Number: 300 Registered: Feb-05 | thanks again man. |
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Silver Member Username: Riebread77Post Number: 608 Registered: Jun-05 | use class D for subwoofers, class AB for mids and highs...heres a representation of the difference Class A ___________________ Class B --------------------------------- Class D - - - - - - - - - - - - - - - - - Distortion is less noticeable in lower frequencies, thats why class D should only be used for subwoofer amps. |
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Silver Member Username: Basshead86Ocala, FL USA Post Number: 869 Registered: Aug-05 | on a Class D amp, the transistors can't switch in the "on/off phase" fast enough to produce a signal that is audibly acceptable above 200hz. i think Glass said that once. |
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Silver Member Username: GoonPost Number: 301 Registered: Feb-05 | ocala? i'm orlando foo |
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Gold Member Username: Jonathan_fGA USA Post Number: 4642 Registered: May-04 | Class D: A continuously varying analog waveform (that which is coming from the RCAs of your head unit) is converted into a binary signal, hence the on/off nature of the output devices. There will be a positive and negative voltage rail, and the transistors will switch between the two. Most of these amps (at least the good ones) use PWM (Pulse width modulation). What PWM does is uses the analog input signal (from your RCAs) to control the average percentage of time the transistor spends turned fully on, known as its duty cycle. The PWM signal is generated by comparing the analog input signal with a triangle waveform--one that continuously sweeps linearly from a low to a high value and back again. To do that, both signals are fed into an analog comparator whose output is high whenever the analog signal has the higher instantaneous value, and low when the opposite is true. The output of this analog comparator is a waveform that has the information of the original analog signal and yet switches between just two values. In a Class D amplifier, this PWM waveform acts as a binary control signal that switches the transistors on and off depending on the amplitude of the analog input. Changing the power supply voltages changes the amount of amplification. After the amplification, that PWM wave has to be passed through a filter that lets lower-frequency signals through while weakening the higher-frequency ones. The low-pass filter does this by smoothing the switching waveform, in effect suppressing the rapid changes in the output waveform and leaving only its average value. At the same time it filters out noises caused by the switching process itself. The process has a lot of high frequency content that absolutely must be filtered out. |
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Gold Member Username: CarguyPost Number: 4205 Registered: Nov-04 | Muddy, take a look at Zapco C2K 9. It has a frequency response of 20Hz - 20Khz. |
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Silver Member Username: Basshead86Ocala, FL USA Post Number: 876 Registered: Aug-05 | What's Goin Down In O-Town? lol that's pretty cool, but uhhh... Suggested Retail $ 2499.00, you can have it!lol i prefer A/B for my mids and highs, and D for my bass.  |
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Silver Member Username: GoonPost Number: 302 Registered: Feb-05 | not a damn thing, rain rain and more rain. i'm on a tight budget, so i'm forced to possibly take a audiobahn/ PG octane route. the pg is a 4 channel bridged to 400x2 at 4ohms. what do you guys think? i wish i could get something better, but it's tough being a student. |
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Silver Member Username: Basshead86Ocala, FL USA Post Number: 878 Registered: Aug-05 | yeah, its been very windy/rainy here the past few days. if you were to pick between those two amps, i would go with the PG. just cuz i don't care for audiobahn. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9903 Registered: Dec-03 | http://www.wickedcases.com/caraudio/ampspecs.html last section covers amplifier classes. simply put, a class AB amp has bettr sound quality, is capable of operating at full range, and draws more current, producing more heat with lower efficiency. class D amplifiers are for subs only, produce higher distortion at or near peak output, draw less current, produce less heat, are more efficient, and as a result put out more power in a smaller package. They also tend to come in larger power classes than any class AB amplifiers, and cost less per watt. |
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Bronze Member Username: VuyodaddyPost Number: 21 Registered: Jun-05 | Crap... well I just bought a class AB Rockford p5002 amp instead of my originally planned Alpine mrd-m605 class d amp to run a single Type R 12". My friends at Bestbuy said it'd sound better anyway. But I heard the thing gets hot. Did I make the right decision or should I opt for the Alpine amp again? |
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Silver Member Username: GoonPost Number: 304 Registered: Feb-05 | I don't know about car amps, but I assume it's the same as the computers I deal with. HEAT KILLS. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9931 Registered: Dec-03 | don't assume. the most inefficient amplifier classes also happen to be the highest in accuracy and sound quality with the lowest distortion levels (class A) but yes in a sense, heat is always the enemy of electronics. That being said however, it's not going to make a big difference with these car amps per se.. but the class AB amp will draw more current per watt of output power. |
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Silver Member Username: GoonPost Number: 305 Registered: Feb-05 | oK, the dmm has spoken. It set it to DCV 10 beacuase I didn't get as reading on the other settings 50-ect. the meter stopped just below 10,like around 8-9. from what i've been told it should have gone over to about 12-14v? so apparently i'm not getting enough power? what could cause this? |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9934 Registered: Dec-03 | is that with the engine running or from battery juice? |
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Silver Member Username: GoonPost Number: 306 Registered: Feb-05 | with the engine running. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9937 Registered: Dec-03 | try with the engine off if voltage is still low, chances are you have a battery with a damaged cell. just need a new battery for the car |
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Silver Member Username: GoonPost Number: 307 Registered: Feb-05 | ok with the engine off and the dial set to dvc 10, it went way past the 10 all the way to the other end, inbetween the last two numbers on the meter. so little voltage with the car on, and a lot with the car off....i'm so confused. i'm no expert but could this be an alternator problem? |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 9946 Registered: Dec-03 | yup battery is good alternator may be bad. you can get it tested at any auto parts store for free usually |
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Silver Member Username: GoonPost Number: 309 Registered: Feb-05 | glass thanks again man. this is becomming very frustrating for me. so more than likly the amp is still good, just not enough juice to power it on? at this point is there any way to test it? |
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Gold Member Username: CarguyPost Number: 4211 Registered: Nov-04 | Howie, if you have 12 ps or car battery charger, you can test the amp with it. I would strongly urge you to drive to a shop asap and either get your car tested or replace the alternator. Your battery will die very shortly cause nothing's charging it. I also wouldn't drive too far either. All it takes is the battery to drop below 10v and everything will start shutting down. You can't get a boost after that cause there will be no other source of power to keep the car going. In fact, disconnect everything that's not essential to save power. |
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Silver Member Username: GoonPost Number: 310 Registered: Feb-05 | i do have a battery charger...but from the readings i got my alternator is ready to die? |
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Gold Member Username: Jonathan_fGA USA Post Number: 4646 Registered: May-04 | "i do have a battery charger...but from the readings i got my alternator is ready to die?" Alternator or voltage regulator. External voltage regulators are a thing of the past, so yeah, you'll likely be replacing your alternator. |
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Bronze Member Username: VuyodaddyPost Number: 22 Registered: Jun-05 | Prepare for a noob question: Well, if the amp is running hot, is that because I'm playing the bass too high? If I want to preserve my investment, should I look for some cooling solutions? I figured the amp as made to be used as is, and no modifications would be necessary, but I don't wanna damage my amp. It does have auto shutoff to prevent overheating though. Any advice guys? |
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Silver Member Username: GoonPost Number: 311 Registered: Feb-05 | well i guess if ill be getting a new alt i should spring for a large one. anyone know some places that sell some for a decent price, refurbs even. |
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Silver Member Username: GoonPost Number: 312 Registered: Feb-05 | isaac, how would you test it with a car charger? i would think positive to power wire and negative to ground...anything i am missing? thanks man. |
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Silver Member Username: Mikechec9Http://www.cardomain.c... Post Number: 851 Registered: May-05 | "Crap... well I just bought a class AB Rockford p5002 amp instead of my originally planned Alpine mrd-m605 class d amp to run a single Type R 12". My friends at Bestbuy said it'd sound better anyway. But I heard the thing gets hot. Did I make the right decision or should I opt for the Alpine amp again?" i'd say good choice. i have personally moved passed class D's a while back, and don't plan on returning (at least not any time soon). The only problem is a/b high output amps are becomming harder to come by every year. and with that, class D's are becomming inceasingly more advanced and compatable (actually running components. not as effectively as a, b, a/b, etc, but running them none-the-less). my sub amps are a/b and put out a true 1600-1800 watts a piece. not at all common nowadays. |
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Silver Member Username: Mikechec9Http://www.cardomain.c... Post Number: 852 Registered: May-05 | come to think of it, even they are currently discontinued. |
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Silver Member Username: Mikechec9Http://www.cardomain.c... Post Number: 853 Registered: May-05 | just came home from teaching these kids, so i feel like ranting a bit anyway. "good amps" are diminishing left and right. it used to be that US made (more or less) = great amps. PPI, PG, RF, Soundstream, Orion.. now PPI looks like a plastic airport bench, PG has cute LED's on their amps (and subs?) Soundstream has also sold out to the overseas, barely better than cheap, commercial side- and orion, bless their hearts, have respectfully opted to just stop production altogether, unless they merged with another company somewhere. now you have to pretty much go exotic when nabbing a truly solid amp. building "quality" just doesn't yield adequate profits nowadays... and it IS capitalism after all. i wonder if, like the subs of late, there will be a true amp revolution (other than that of the class D's) where internet shops will explode onto the scene with great, solid amps. the main difference i see is the difference between listening to a generic watt and a specific signal attempting to come as close as possible to reproducing that of the source. but hey.. i'm just ranting. |
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Silver Member Username: Mikechec9Http://www.cardomain.c... Post Number: 854 Registered: May-05 | just checked out the new orions. havn't heard anything about them, but i can rest positive that they aren't the amps of yore. |
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Gold Member Username: CarguyPost Number: 4227 Registered: Nov-04 | Howie, remote wire to positive too. That will turn on the amp. Just make sure the charger is fairly big, as in 20A or higher. I think Walmart/Sams club/Costco sells battery charger that's 200A+ for like $130. You should attach 1F capcacitor for filtering. |
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Silver Member Username: GoonPost Number: 313 Registered: Feb-05 | thanks again man... just to clerify though, with the readings i got at the d-block with the dmm, that WOULD cause my amp to not turn on correct? |
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Gold Member Username: CarguyPost Number: 4228 Registered: Nov-04 | Yes, you don't have enough voltage to power anything at your d block. |
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Silver Member Username: JustintoxicatedPost Number: 155 Registered: Jan-05 | You can always get a DLS Ultimate amp 1200 True watts of A/B Power! Plus you can add a fan (there is one built in already) cap etc right to the amp.. A bit pricy though :P |
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Silver Member Username: JustintoxicatedPost Number: 156 Registered: Jan-05 | Oh heres da links http://www.dls.se/english/fstark/a3n.htm http://www.dls.se/english/fstark/a6n.htm and you can get them here but I can get them cheaper :P www.infinitecaraudio.com |
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