Running Benchmark AHB2 in bridged mode and 4 Ohm Speaker

Sorry your are correct it’s 6ohm as 4ohm they could not test, obviously current limited at 18amps and shut down, still not great 18amp shut down in bridged mode. And still 100w short of doubling into 6ohm anyway, still current sagging, should be around 570w not 470w

Benchmark specs given to Stereophile.:
" Output power, bridged-mono mode: 200W into 16 ohms (26dBW), 380W into 8 ohms (25.8dBW), 480W into 6 ohms (25dBW). Output current: 18 amps/channel, both channels driven, 18 amps shut-down threshold."

Cheers George

Power specified at 6ohm is 130W. Theoretical ideal power bridged at 6ohm should be 520W and is 480W (7.7% less). Also current was changed to 29A per channel. Perhaps 18A specification was for the early versions.

The misinformation in this thread from an individual who should know better is a little disturbing. The motive escapes me, but it appears to be deliberately malevolent.

From John Atkinson’s measurement comments:
"Commendably, the frequency response was not affected by the setting of the sensitivity switch, or by using the amplifier in bridged-mono mode. However, the ultrasonic response in bridged-mono mode shelved down faster than in stereo mode, and as the two channels’ output stages are in series in this mode, the output impedance, again including the 6’ of speaker cable, was higher than in stereo, at 0.14 ohm at 1kHz."

And his final comment:
"Benchmark Media Systems’ AHB2 is an extraordinary amplifier. Not only does its performance lie at the limits of what is possible for me to reliably test, it packs high power into a very small package, especially when used in bridged-mono mode. It is truly a high-resolution amplifier."
Read more at https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements#LdQ7lf...

I suggest people interested in the AHB2 seek out out tests/opinions from reputable sources that have actual hands on experience with the amp. Technical queries should then be directed to Benchmark themselves to avoid speculation and misinformation.

Perhaps 18A specification was for the early versions. R

Yes of course they were, just like when Sterophile does a mediocre review, the manufacturers comments always say they must have sent a faulty one in for the review.
Wouldn’t you think at they would send the best possible tweaked one they could!!!!
What a load of ****

Cheers George

I am amazed this has not been answered and laid to rest. What seems to be the problem? The 29 amps will only be supplied by the amplifier if the load resistance is low and the voltage is high enough to produce that current. Perhaps its the order of things. Voltage first, then resistance then figure the current. I think we have all come to agree that bridging does not allow the amplifier to provide more than 29 amps. Bridging just allows twice the voltage which increases the OPPORTUNITY for more current to flow, but its still limited to 29 amps. Which, BTW, is not enough current form some ESLs played loud.

I promise you that all amps that are claimed to do 100 watts into 8 ohms, 200 into 4 and 400 watts into 2 ohms have quite a bit more power at 8 ohms than stated. Thats how they do it, Its specmanship and nothing wrong with. They do it for the same reason that some here want to see those numbers keep doubling. If you truly have only 100 watts at 8 ohms you will not be able to double down. Not Possible.

Conventional amps have Emitter or Source resistors whose value becomes significant at low impedance loads, the resistance of wire and traces startes to come into play. Mainly the sag is in the power transformer. 

When you look in an amp and see nice heavy wire going to the speaker keep in mind that there are several hundred feet of rather thin wire in the power transformer.