VFL 4480.1 - actual output

[basscube5]

Hey Guys!

I bought a VFL 4480 recently to run two XFL 10s. I'm not in a position right now to start building a box and installing everything but my curiosities got the best of me today so I did a little test. I hooked up the 4480 temporarily and ran a clean 40hz test tone through it to see what kind of output voltage I could get while keeping an eye on things with an Oscope. I have to say I'm a little disappointed with what I came up with... With a battery voltage of 13.9V the most I could get (clean) at the speaker output is 34V. This translates to roughly 1156 friggin watts at 1ohm, nowhere near what this amp is hyped at. I used a fluke 114 to take the voltage measurement, I also checked it with my clamp meter (does rms voltage as well) both came up with the same number.

Yes, I realize I don't post here much, but I'm no noob to this sort of stuff. Figured I'd give the AB stuff a shot, but so far I dunno. Thoughts? Dud maybe? these things don't like 40HZ tones maybe? I saw a thread here a while back where a fellow claimed 50v at the speaker outputs (no load). I did get this from ebay, where I'm in canada I'm sol as far as warranty goes regardless so I went the cheapest route possible.

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[Jeffdachef 5,000+ posts]

Yup. Thats the 4480 hybrid for you and you got people swearing by this amp left and right... what a joke.

I got a sh*t one too. Many people on facebook and some on CACO hate this amp too for the reason of garbage output. Their quality control *****. Apparently some put out power, but majority dont.

 

[basscube5]

just for kicks I'm going to take another swipe at it here in a bit. I'll try a 50hz tone this time too. I'm going to yank the cover off and measure the rail voltage as well.

But yeah, I'm with you Jeff, if this is the case this POS isn't even going in my car. I'll report back.

 

[MrFoca]

I'd wire it down super low and watch smoke come out of it.

 

[michaellane 5,000+ posts]

My buddy says he got close to 3k outta his but idk

 

[basscube5]

Figured I'd post another reply. I was a bit quick to slander AB earlier, I did some more testing and based on what I found 2-2500 seems possible.

I have a Hantek pc based oscilloscope, gotta love the chinese and their instructions. Anyway, the Hantek works real well but it turns out if you feed it any more than about 34 VAC the tops of the waves flatten out, the same as if it is receiving a clipped signal. I rigged up a voltage divider and all is well now, it reads as high as I want.

The power supply is unregulated, no surprise there. The rail voltages are as follows

Battery 12.7V, rails +-65VDC (131 VDC P-P)

Battery 14.0V, rails +-75V (150 VDC P-P)

Unloaded output voltages w/50HZ test tone (Clean sine wave out):

Battery 12.8V, 48V out

Battery 14.0V, 52V out

Just for kicks I hooked up one of the XFLs in free air, obviously it will be a lot different loaded in a box but it's the only load I have. This is a D4 woofer with both coils in parallel. I don't have any giant resistors around. So take these numbers for what their worth:

Battery 12.6V, 43V out

Battery 14.0V, 48v out.

All these readings were with perfectly clean waveforms on the speaker output. If you drive the amp into a soft clip you can add roughly another 5-6V to the output voltages listed above before the tone of the woofer's changed at all. It's no amp dyno I realize but 52V into 1 ohm is 2704 VA if it can keep the voltage up and not fill my trunk with smoke. Not bad for such a small amp.

 

[wew lad 5,000+ posts]

sounds right to me..although i would of expected more voltage, knowing how much current it made would help

 

[tc300 10+ year member]

i was disappointed with the vfl i got... it was to replace a mmats dhcx2200.1, was nothing close it!! now have a audio technix AT 1200.1 and its more close to the mmats amp

 

[basscube5]

sounds right to me..although i would of expected more voltage, knowing how much current it made would help

I did measure current in the leads going to the woofer, but it was really low. Maybe it was my meter but most likely it's because the sub was in free air and the impedance went through the roof. Just the same I was powering the amp off a 20' set of booster cables with the last 12" from the clamps to the amp's inputs made up from 10 awg speaker wire. The voltage stayed as per my notes above but it wouldn't have been able to make any big power under a heavy load. If I had a resistor bank I'd hook it up for real and run the **** out of it. It wouldn't be hard to figure out power factor and real watts, my Oscope has 2 inputs.

You can get 65+ volts at the speaker output but the wave gets real ugly. You can hear it in the woofer when the THD gets excessive, it's very obvious, it goes from a hummm to a buzz over a span of about 2 volts, not super scientific I know but it is surprising how ugly the wave has to get before you can actually hear it. 55-57 volts is about the limit from what I found yesterday. All theoretical at this point but 55 volts and a PF of 0.8 at 1 ohm is 2420 wrms...

 

[wew lad 5,000+ posts]

I did measure current in the leads going to the woofer, but it was really low. Maybe it was my meter but most likely it's because the sub was in free air and the impedance went through the roof. Just the same I was powering the amp off a 20' set of booster cables with the last 12" from the clamps to the amp's inputs made up from 10 awg speaker wire. The voltage stayed as per my notes above but it wouldn't have been able to make any big power under a heavy load. If I had a resistor bank I'd hook it up for real and run the **** out of it. It wouldn't be hard to figure out power factor and real watts, my Oscope has 2 inputs.
You can get 65+ volts at the speaker output but the wave gets real ugly. You can hear it in the woofer when the THD gets excessive, it's very obvious, it goes from a hummm to a buzz over a span of about 2 volts, not super scientific I know but it is surprising how ugly the wave has to get before you can actually hear it. 55-57 volts is about the limit from what I found yesterday. All theoretical at this point but 55 volts and a PF of 0.8 at 1 ohm is 2420 wrms...

what did you use to measure current? should of gotten at least 20 amps

 

[basscube5]

what did you use to measure current? should of gotten at least 20 amps

Just a clamp meter, it reads AC or DC current. I was expecting more current too. It was pulling 13A @14V from the battery and putting 48V @ 3A to the woofer, which I think are junk numbers either because the power supply wasn't stiff enough or the woofer was wayyy high impedance wise. This was all meant to be a voltage test anyway, the amp needs a much better power supply to be able to get decent current numbers.

Regardless, +- 75V at the rails answered a lot of questions/concerns I had. I can't see any manufacturer gearing up a power supply like that if the amp wasn't going to put something decent out the other end.

Shame there aren't any amp dynos close, I've never seen any AB product tested.

 

[wew lad 5,000+ posts]

Just a clamp meter, it reads AC or DC current. I was expecting more current too. It was pulling 13A @14V from the battery and putting 48V @ 3A to the woofer, which I think are junk numbers either because the power supply wasn't stiff enough or the woofer was wayyy high impedance wise. This was all meant to be a voltage test anyway, the amp needs a much better power supply to be able to get decent current numbers.
Regardless, +- 75V at the rails answered a lot of questions/concerns I had. I can't see any manufacturer gearing up a power supply like that if the amp wasn't going to put something decent out the other end.

Shame there aren't any amp dynos close, I've never seen any AB product tested.

it sounds like there's definitely a problem with your testing, the rail voltages sound correct, but the amperage out/in is low, when you get it in your vehicle with a good power supply measure it again and calculate your rise..

 

[basscube5]

it sounds like there's definitely a problem with your testing, the rail voltages sound correct, but the amperage out/in is low, when you get it in your vehicle with a good power supply measure it again and calculate your rise..

I agree 100%, the current numbers aren't right. You can't fake a sine wave though, I'm satisfied enough to proceed installing it at least. It's only running 2 XFL 10s @ 1ohm, if it can do close to 2K rms I'm hoping it'll be lots.