Jump to content

ThxOne

Class A/B pulling more current than my Class D???

Recommended Posts

Is it normal for my class A/B amp to pull more current than my sub amp? I have never seen this in any other system I have put together... at least I have not noticed it. Specifics... My US Acoustics Barbara Ann 4 channel class A/B amp is getting full range signals of 60hz and up from my head unit. When I play a few specific songs with strong midbass up to and above 120hz, which is what my sub is crossed over at, Barbara Ann yanks a crap ton of current from the electrical system. I verified that it is that amp by turning off the sub from the head unit. Is this normal? Is class A/B that much of a power hog? I am talking 2V+ on 3 different gauges. The dash, the cap and a multimeter. I have to REALLY push the sub amp to make it drop voltage on the gauges at the same volume by cranking my remote gain knob. Thanks everyone.

Share this post


Link to post
Share on other sites

What's your electrical like? Could be the gain is too high vs your sub amp gain, which might be pulling more current.

Share this post


Link to post
Share on other sites

What do you mean by "What's my electrical like?" I have to admit... I did not set my amp gains with my DMM. My volume of my head unit goes to 35... I set it to 30 then adjusted the gains by ear to an "undistorted tolerable level"

Share this post


Link to post
Share on other sites

Your electrical...what does it consist of? Anything upgraded? big 3 done? Those sorts of things. That 35 should be closer to 32-33 but it will depend upon HU because of different pre out voltages (2-5 volts).

Share this post


Link to post
Share on other sites

Just what's done in my sig... Big 4, 1/0 awg from battery to distribution block split to dual 4 awg... one for each amp. Dual 4 awg ground wires into a distribution block which turns into a single 1/0 awg to chassis ground. 150 amp alternator, 2 farad stinger cap.

Share this post


Link to post
Share on other sites
Just what's done in my sig... Big 4, 1/0 awg from battery to distribution block split to dual 4 awg... one for each amp. Dual 4 awg ground wires into a distribution block which turns into a single 1/0 awg to chassis ground. 150 amp alternator, 2 farad stinger cap.

 

Why are you running 2 caps? Once you beef up your electrical, those are pretty worthless.

Share this post


Link to post
Share on other sites

It's a single capacitor of 2 Farad capacitance. They are actually very useful and functional.

Share this post


Link to post
Share on other sites
Is it normal for my class A/B amp to pull more current than my sub amp? I have never seen this in any other system I have put together... at least I have not noticed it. Specifics... My US Acoustics Barbara Ann 4 channel class A/B amp is getting full range signals of 60hz and up from my head unit. When I play a few specific songs with strong midbass up to and above 120hz, which is what my sub is crossed over at, Barbara Ann yanks a crap ton of current from the electrical system. I verified that it is that amp by turning off the sub from the head unit. Is this normal? Is class A/B that much of a power hog? I am talking 2V+ on 3 different gauges. The dash, the cap and a multimeter. I have to REALLY push the sub amp to make it drop voltage on the gauges at the same volume by cranking my remote gain knob. Thanks everyone.

 

it can pull a lot of current from clipping. Class ABs clip much more softer so you dont really notice the distortion until a heavy clip but where you are at right now is definitely clipping if the AB amp is drawing more current than your sub amp.

 

That cap is useless. Doesnt store enough energy, doesnt make any energy. All it does is reduce power going to your amps which is not healthy for your amps at all.

Share this post


Link to post
Share on other sites

It could very well be clipping. Again... I have yet to set the gains with my DMM. I shall do that tomorrow. I have actually seen that video in the past and many others on whether or not caps are worth anything. There are MANY companies out there selling crap and I am sure that has soured many people on capacitors. For me, I know they work if you don't buy a crap capacitor. My amplifiers pull power... lots of it. After the alternator upgrade, voltage was better but still dropped way down to 9.9V, then after the big 4 upgrade it helped and the lowest it dropped was 10.5 to 10.6ish volts... finally I added the cap... it helped. 11.2V is the lowest it has dropped since adding the cap. You all own many caps because they work. Take a look in your amplifiers. Caps... lots of them. But I digress... I'm just inquiring about the class A/B situation as I haven't had this issue before :)

Share this post


Link to post
Share on other sites
It could very well be clipping. Again... I have yet to set the gains with my DMM. I shall do that tomorrow. I have actually seen that video in the past and many others on whether or not caps are worth anything. There are MANY companies out there selling crap and I am sure that has soured many people on capacitors. For me, I know they work if you don't buy a crap capacitor. My amplifiers pull power... lots of it. After the alternator upgrade, voltage was better but still dropped way down to 9.9V, then after the big 4 upgrade it helped and the lowest it dropped was 10.5 to 10.6ish volts... finally I added the cap... it helped. 11.2V is the lowest it has dropped since adding the cap. You all own many caps because they work. Take a look in your amplifiers. Caps... lots of them. But I digress... I'm just inquiring about the class A/B situation as I haven't had this issue before :)

 

Something is seriously wrong with your electrical setup if you are dropping to 10-11 volts with a 150 amp alt on that small of a sound system setup. I'd legit get that alt tested, check your pulley system because my buddy with a stock 150 amp jeep alt is running a 2600 rms sub amp, two 100 x 4 amps with one of them bridged and dropping only to 13.2, all he has is a 2ndary battery. Even before the battery upgrade, the lowest he dropped was 12.6 volts.

 

With the cap, You are taking voltages at the battery. You need to take voltages at the amplifier. Good chance that your amps are seeing a much lower voltage than the battery due to the cap restricting power flow to the amp.

 

The only cap that works is a maxwell super cap and you need 6 of those in a bank over 3500 farads and you need a beefy alternator. Otherwise these traditional caps are literally worthless for car audio. You would have been 1000x better off with a 12v lawnmower battery instead which costs the same price but actually stores a lot of power.

 

You also NEVER use a multi-meter to set gains for mids and highs. Dont fall into the noob trap where people who have no understanding about the correlation of how recording levels in music affect head unit pre-out which affects amplifier output and those idiots make blind recommendations to use a multi-meter to set gains trying to play it off as a legit professional way of setting gains... Absolutely retarded.

Share this post


Link to post
Share on other sites

Small? Between the two amplifiers, the system is capable of pulling well over 200 amps of current. So yeah, when I am cranked up and I can see the voltage drop, I am sure I am not far from it. These are legit rated amplifiers... I can't speak intelligently on your buddies amplifiers but I have personally run a "2500 watt RMS" amp before on a pair of 12's and my "small" punch 10 and "small" punch amp hits lower and louder than that "2500 watt" amp. Just because the box says it... well, you know.

Share this post


Link to post
Share on other sites
Small? Between the two amplifiers, the system is capable of pulling well over 200 amps of current. So yeah, when I am cranked up and I can see the voltage drop, I am sure I am not far from it. These are legit rated amplifiers... I can't speak intelligently on your buddies amplifiers but I have personally run a "2500 watt RMS" amp before on a pair of 12's and my "small" punch 10 and "small" punch amp hits lower and louder than that "2500 watt" amp. Just because the box says it... well, you know.

 

yeah its not a garbage 2k if thats what you are thinking. Solid korean built, tank does 2700 certified at 1 ohm resistive on the amp dyno. https://www.youtube.com/watch?v=_Qr8uhLD5tA. Your prime does about 1400 watts at 1 ohm resistive.

Only certified numbers matter here.

 

Your system IS small and no it does not pull 200 amps of current, not even close. This is from you not understanding how recording levels in music works and what impedance rise is. You wire to 1 ohm, you are not going to get 1 ohm at all, as the coil moves through the magnetic gap, the ohm load shifts. Due to this phenomenon the average impedance the amplifier will see while the woofer is being played rises from what is measured at in a resting or reactive free air state. This impedance shift is highly dependent upon the enclosure and how the enclosure interacts with the vehicle it’s in, so there’s no way to calculate what level of rise you will before the system is installed. How we actually test it is through clamp tests to see how much power and current your amp is actually producing and pulling. Most of the times your rise is 3x your nominal wiring so right now you are at best seeing 2-3 ohm power out of the amp if you wired to 1 ohm.

 

The other factor that you completely disregarded is that music is not a constant sine wave, you are not going to draw max power out of the amp at all times. Also that music has different recording levels so the amount of power produced is way less depending on the track. So all in all, your setup is MUCH smaller than you think. Most people's setup and electrical demands is MUCH smaller than they think because they literally never compete in competitions where we actually measure every single aspect of your system due to class restrictions.

Share this post


Link to post
Share on other sites
Good chance that your amps are seeing a much lower voltage than the battery due to the cap restricting power flow to the amp.

 

I re-read your post... your statement is physically and electrically impossible. The flow of electrons is going to follow the path of least resistance... even if the cap blew up, as long as the cable coming from the battery is still connected to the cable going to the amp with no break, electrons are still going to flow. The cap cannot impede the flow of electricity if the connections are correct. It fills up with electricity as fast as you can blink your eyes and stores it like a battery, only faster. Once its full, it will chill there until a demand for that stored energy is needed... like a battery, only faster. Then, since it is faster... and closer to the amp, the electrons will flow from the CAP to the amp... mind you, current is still coming from the battery and flowing over the SAME cable, though now, it doesn't have to drain from the battery so the alternator doesn't have to divert electricity from running the vehicle to replenish that battery. Why? Because the cap took care of it. Now if you are running a bunch of subs and 10's of thousands of watts of power then you are right... a 1,2 or even a 10 farad cap will do nothing for you. Also, it is fine to set your gains with a DMM... the output terminals on the amp produce A/C current. At a given frequency that A/C current has a specific voltage that can be measured. If it can be reproduced and measured then it can be used to set your gains. Is it dead on balls accurate, no, but it can be VERY close. Close is good enough because that voltage is going to change with music... even if set professionally, which I hate to tell you, I have seen done with DMM.

Share this post


Link to post
Share on other sites

Just because I have just joined this forum does NOT mean I am a "noob" or that I am ignorant of anything. I have been dealing with car audio since 1990. You shouldn't assume because you know some things that others are ignorant of those things or because a person may use equipment that you may not use that they are ignorant noobs.

Share this post


Link to post
Share on other sites
I re-read your post... your statement is physically and electrically impossible. The flow of electrons is going to follow the path of least resistance... even if the cap blew up, as long as the cable coming from the battery is still connected to the cable going to the amp with no break, electrons are still going to flow. The cap cannot impede the flow of electricity if the connections are correct. It fills up with electricity as fast as you can blink your eyes and stores it like a battery, only faster. Once its full, it will chill there until a demand for that stored energy is needed... like a battery, only faster. Then, since it is faster... and closer to the amp, the electrons will flow from the CAP to the amp... mind you, current is still coming from the battery and flowing over the SAME cable, though now, it doesn't have to drain from the battery so the alternator doesn't have to divert electricity from running the vehicle to replenish that battery. Why? Because the cap took care of it. Now if you are running a bunch of subs and 10's of thousands of watts of power then you are right... a 1,2 or even a 10 farad cap will do nothing for you. Also, it is fine to set your gains with a DMM... the output terminals on the amp produce A/C current. At a given frequency that A/C current has a specific voltage that can be measured. If it can be reproduced and measured then it can be used to set your gains. Is it dead on balls accurate, no, but it can be VERY close. Close is good enough because that voltage is going to change with music... even if set professionally, which I hate to tell you, I have seen done with DMM.

 

Nice wikipedia copy and paste.

 

Do you not realize how LITTLE 1-10 farads of power is? Its literally useless in any system producing actual power over 1000 watts.

 

You still have no proper understanding of how recording levels in bass works. I'm too tired to rewrite this sh*t again so here's another thread where I explained it to someone using a DD-1 AKA your multi-meter method on steroids. Music is not a sine wave and you are using a sine wave at a set db level to set the gains while your music's recording levels are all over the place.

 

http://www.caraudio.com/forums/subwoofers/636288-subwoofer-getting-smelly-after-about-10-mins-playing-2.html

 

Just because I have just joined this forum does NOT mean I am a "noob" or that I am ignorant of anything. I have been dealing with car audio since 1990. You shouldn't assume because you know some things that others are ignorant of those things or because a person may use equipment that you may not use that they are ignorant noobs.

 

just because you've done it long doesn't mean you are up to date with proper knowledge of how sh*t actually works. AKA recording levels in music. I recommend downloading audacity and actually analyzing your music. Along with getting your electrical setup above 12 volts which literally should be easy on a 150 amp alt.

Share this post


Link to post
Share on other sites
Nice wikipedia copy and paste.

 

I don't need to Copy and Paste anything... that is knowledge accumulated from decades of dealing with car audio. Ok Steve Meade fan boy... when HE uses his OWN DESIGNED DD-1, he uses test tones!!!!! 40hz, 1000hz!!!! Sign waves!!!! Why???? Because you can't accurately set gains with music. Your argument is pointless. I never said I set my gains with music... go get some sleep.

Share this post


Link to post
Share on other sites
I don't need to Copy and Paste anything... that is knowledge accumulated from decades of dealing with car audio. Ok Steve Meade fan boy... when HE uses his OWN DESIGNED DD-1, he uses test tones!!!!! 40hz, 1000hz!!!! Sign waves!!!! Why???? Because you can't accurately set gains with music. Your argument is pointless. I never said I set my gains with music... go get some sleep.

 

you didnt read jack sh*t. Its literally how I dismantle the DD-1 and prove its a garbage buy and a noob trap. If you have decades of dealing with car audio you wouldn't say stupid sh*t as drawing 200 amps of current nor that a capacitor is helpful, nor that you have a 150 amp alt and dropping to 10-11 volts Along with having legit ZERO understanding of how music recording level directly affects amplifier power output. Talk about 28 years of car audio cluelessness. Holy fuck

Share this post


Link to post
Share on other sites
just because you've done it long doesn't mean you are up to date with proper knowledge of how sh*t actually works. AKA recording levels in music. I recommend downloading audacity and actually analyzing your music. Along with getting your electrical setup above 12 volts which literally should be easy on a 150 amp alt.

 

Oh dear lord. You are right. I stopped my knowledge intake in 1993. I don't know anything about electricity, car stereos, or music. I will go and dismantle the stereo in my Jeep, I will remove all my recording software from my computer and throw away my guitars, and I shall put my stock alternator back in. No... wait, That's right... This was about class A/B amplifiers and if they draw more current than class D amplifiers. Here is what I think. I think that it is pulling and does pull more current because it is less efficient. After I set my gains... with a DMM and adjust a few things I will re-evaluate if anything else needs to be done. By the way, my idle voltage is 14.1V at the amplifiers with no music playing and the engine rotating at 700rpms. That's revolutions per minute. Revolutions are complete rotations... rotations are when something spins on an axis... an axis is a central pivot or rotation point

Share this post


Link to post
Share on other sites
If you have decades of dealing with car audio you wouldn't say stupid sh*t as drawing 200 amps of current

 

And you say I didn't read.... I never said it draws 200amps... I SAID IT IS CAPABLE OF DRAWING 200 AMPS AND WHEN MY GAUGE IS DROPPING, IT'S PROBABLY CLOSE.

Share this post


Link to post
Share on other sites
Just because I have just joined this forum does NOT mean I am a "noob" or that I am ignorant of anything. I have been dealing with car audio since 1990. You shouldn't assume because you know some things that others are ignorant of those things or because a person may use equipment that you may not use that they are ignorant noobs.

 

Oh good, I'm not late to the party :popcorn:

 

Well, you did question me regarding your electrical...which tells me you had no clue what I was talking about.

 

Oh, btw, don't argue with Jeff.....one of the smartest persons on here.

Share this post


Link to post
Share on other sites
you didnt read jack sh*t. Its literally how I dismantle the DD-1 and prove its a garbage buy and a noob trap. If you have decades of dealing with car audio you wouldn't say stupid sh*t as drawing 200 amps of current nor that a capacitor is helpful, nor that you have a 150 amp alt and dropping to 10-11 volts Along with having legit ZERO understanding of how music recording level directly affects amplifier power output. Talk about 28 years of car audio cluelessness. Holy fuck

 

:laugh:

 

Oh man here we go...

Share this post


Link to post
Share on other sites
Oh dear lord. You are right. I stopped my knowledge intake in 1993. I don't know anything about electricity, car stereos, or music. I will go and dismantle the stereo in my Jeep, I will remove all my recording software from my computer and throw away my guitars, and I shall put my stock alternator back in. No... wait, That's right... This was about class A/B amplifiers and if they draw more current than class D amplifiers. Here is what I think. I think that it is pulling and does pull more current because it is less efficient. After I set my gains... with a DMM and adjust a few things I will re-evaluate if anything else needs to be done. By the way, my idle voltage is 14.1V at the amplifiers with no music playing and the engine rotating at 700rpms. That's revolutions per minute. Revolutions are complete rotations... rotations are when something spins on an axis... an axis is a central pivot or rotation point

 

Then you should already know that your amps aren't pulling anything if your audio is turned off. Duh!

Share this post


Link to post
Share on other sites
And you say I didn't read.... I never said it draws 200amps... I SAID IT IS CAPABLE OF DRAWING 200 AMPS AND WHEN MY GAUGE IS DROPPING, IT'S PROBABLY CLOSE.

 

Did you measure the 200 amperage yourself? How did you come up with that figure number on such a small modest system? Even if your pushing everything to it's limit, bet it's not even close to 200.

Share this post


Link to post
Share on other sites
Oh good, I'm not late to the party :popcorn:

 

Well, you did question me regarding your electrical...which tells me you had no clue what I was talking about.

 

Oh, btw, don't argue with Jeff.....one of the smartest persons on here.

 

Oh I will argue with him. I ask you what you meant because you ask about my electrical, all of which is in my sig. I was clarifying so that YOU and I were on the same page. It was nothing offensive to you nor a lack of knowledge on my part. I won't argue that he is smart, I don't know him other than him making some ignorant or presumptuous statements about me. But that's fine. I was looking for an answer, possibly some suggestions from other car audio enthusiast as I am not so arrogant as to think I know all about everything like some people.

Share this post


Link to post
Share on other sites

If you didn’t know A/B draw more current then you shouldn’t be trying to argue with anyone.

And no you should not be having issues.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×