Infinity Reference Ref 551A Amp Dyno test and Unboxing

[THATpurpleKUSH 5,000+ posts]

Just curious but based on the 60 amp fuse rating and 14.4 volts input voltage the max potential power of this amplifier should be in the neighborhood of 648 watts. Amperage X Voltage = watts at 100% efficiency X .75. That is assuming a total (power supply + amp) efficiency of 75%, which according to the engineer who made that dyno you used is typical for a class D amp. So I guess the 645 watts you got certified jives with what you got on that dyno but not the uncertified result.
The GTX500 should have a max potential power of 540 watts with a 50 amp fuse and 14.4 volts input. My car has a running voltage of 13.6 volts so that number would drop to 510 watts.

The amp is only 2 ohm stable so its more efficient, I'd be willing to bet it's over 80% efficient at 2 ohms. If you have a clamp meter you could measure current draw and calculate efficiency.

Not to mention fuses don't blow instantly so you can pull more current through a fuse than what it's rated for.

 

[bigblank69 10+ year member]

Just curious but based on the 60 amp fuse rating and 14.4 volts input voltage the max potential power of this amplifier should be in the neighborhood of 648 watts. Amperage X Voltage = watts at 100% efficiency X .75. That is assuming a total (power supply + amp) efficiency of 75%, which according to the engineer who made that dyno you used is typical for a class D amp. So I guess the 645 watts you got certified jives with what you got on that dyno but not the uncertified result.
The GTX500 should have a max potential power of 540 watts with a 50 amp fuse and 14.4 volts input. My car has a running voltage of 13.6 volts so that number would drop to 510 watts.

Your assuming the onboard fuse rating is the only amount of power an amp can draw. 60 amps of fusing will not pop instantly with the current they are drawing, they will exceed the amperage rating for a little while before popping. Now if you put on a continuous sine wave and cranked the volume the amp will deplete its capacitance and won't be able to keep up that kind of wattage before popping its fuses.

I have seen a 30 amp fuse take 160 amp load for roughly 100ms before blowing.

I have seen 120amps of fusing on an amp do over 1900W Certified and 2200W Dynamic.

 

[THATpurpleKUSH 5,000+ posts]

Before MECA measured actual power to determine what class you are in, they used to use fuse ratings. I ran a 30a fuse about 12 inches from my amp to get into a low class and I would get about 3-5 seconds before it blew with somewhere around 120-140a of current passing through it.

 

[kr15 5,000+ posts]

Back in meca days I ran a dd m3@ 0.5 on 30a fuse. I clamped around 2500 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Jcsaudio]

I guess it’s plausable. So how long do you think that almost 700 watt uncertified power rating could be sustained before the fuse blows?

Here is what the engineer who made your dyno has to say.



Maybe I can compare the guts of my GTX500 to the Club 5501 and try and decipher a difference other than the fuses.

 

[bigblank69 10+ year member]

Good luck... The GTX500 circuit board is mounted upside down... If you remove the bottom plate all you will see is the bottom of a circuit board....

 

[BOOMINGRANDPA 5,000+ posts]

Oh I'm not rushing to send them back.... Just don't want to hold em to long and get burned... Though I own them so cheap I'm not really super concerned. But I need as much cash retention as possible If I am going to be able to keep up doing these vids. Just invested in upping the production value with a new camera and microphone...

so did u test the wolfram today? really wanted to see cobalt 2500 and xtr 1500 test before cyber monday in case there's a crazy cheap sale..

 

[bigblank69 10+ year member]

Didn't get to it today. Got it all in though, haven't opened it up yet. Got a surprise amp in today that jumped the line. And seeing as it's not mine I got to film it quick.

 

[n2audio 5,000+ posts]

Just curious but based on the 60 amp fuse rating and 14.4 volts input voltage the max potential power of this amplifier should be in the neighborhood of 648 watts. Amperage X Voltage = watts at 100% efficiency X .75. That is assuming a total (power supply + amp) efficiency of 75%, which according to the engineer who made that dyno you used is typical for a class D amp. So I guess the 645 watts you got certified jives with what you got on that dyno but not the uncertified result.
The GTX500 should have a max potential power of 540 watts with a 50 amp fuse and 14.4 volts input. My car has a running voltage of 13.6 volts so that number would drop to 510 watts.

Trying to "confirm" power measurements taken with precision instruments using fuse size as the control is so back asswards I can't come up with an appropriate analogy.

The best you can hope to do by looking at the fuse size is +/-20%. It is a rough approximation at best.

Fuses are fairly imprecise devices. They are supposed to pass 110% rated current basically indefinitely. 135% anywhere from 3/4 sec to 120 sec. 160% from 1/4 sec to 50 sec.

So to try to use them as an accurate representation of the power in a circuit is not going to get you anywhere.

 

[Jcsaudio]

Interesting! Learn something new every day. Attached is a data sheet for automotive ATO fuses that seem to support your claim. http://m.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_atof_datasheet.pdf