Running Benchmark AHB2 in bridged mode and 4 Ohm Speaker

Benchmark have been making ground breaking products for years. They are an embarrassment to most of the old school industry. Out performing incumbent market leaders technically (measurements) by considerable amounts at reasonable cost.

This is healthy and exciting for us as hi-fi customers. Of course reliability is always a concern especially with radical new designs. Time will tell if these new products like the AHB2 and the HPA4 perform as reliably as their DACs.

Of course measurement based design targets measured performance and therefore only address a portion of the market. Flavoured designs like tube amps etc. will always have their important place and many audiophiles will continue to opt for flavour over pure tech specs.

That said. You could consider the AHB2 as a transparent way to drive speakers (if you like the sound of your speakers) and then look to a tube preamplifier to add some sweetness or sizzle to taste.

As I said previously, better in Mono.  :)

Thanks, great response gearbuilder

Get real!!
None of what gearbuilder's copy/pasted post spiel from another thread/member.  https://forum.audiogon.com/discussions/benchmark-ahb2-amplifier-what-to-expect Has anything to do with the OP's 4ohm speakers, and bridging this amp into them. Sure it's a great stereo amp.

Also I would like to know why a whole thread which is gearbuilders only other 4 other posts on the ABH2 the whole of Agon was deleted by admin.
https://forum.audiogon.com/discussions/benchmark-media-high-resolution-amp?highlight=benchmark

 https://forum.audiogon.com/users/gearbuilder

Call me a conspiracy theorist I don't care, just like to know answers.

Cheers George 

None of what gearbuilder's copy/pasted post spiel from another thread/member.  https://forum.audiogon.com/discussions/benchmark-ahb2-amplifier-what-to-expect Has anything to do with the OP's 4ohm speakers, and bridging this amp into them. Sure it's a great stereo amp.

Really?
Lets look at that.
@gearbuilder said:

3) The THD is virtually identical when comparing stereo mode to bridged mono mode. This is achieved through the use of the feed-forward error correction. Every other power amplifier will show a substantial increase in distortion when bridged.

5) The THD produced by the AHB2 does not increase as the impedance decreases. The THD into 2 Ohms, 4 Ohms, 8 Ohms and no load are virtually identical. Again this is a unique characteristic that is achieved through the use of feed-forward error correction.

6) The AHB2 is not just stable into low-impedance loads, it stays clean when driving low impedances. The THD does not change with loading.

Bottom line, the AHB2 is well suited for bridged mono operation into 4-Ohm nominal impedances and the performance is virtually identical to stereo mode except that the power is nearly 4 X higher. Dips in the speaker impedance curve are not a problem and the AHB2 drives these cleanly.

We almost always demonstrate the AHB2 in bridged mono mode at trade shows and have done so with many different hi-fi and pro loudspeakers. In most cases, these demonstrations have used speakers with a 4-Ohm nominal input impedance.

Could the OP get more than sufficient volume with a single AHB2? Most likely.

But @geek101 asked this:

Does running this amp in bridge mode mean each channel will see half the impedance i.e 2 Ohm each when connected to a 4 Ohm speaker. If so will this cause a problem when the speaker dips to 3 or 2 ohms?. 

The answer to the first part is 'yes' the amp will see half the impedance in bridged mode.
The answer to the second part is "the AHB2 is well suited for bridged mono operation into 4-Ohm nominal impedances and the performance is virtually identical to stereo mode except that the power is nearly 4 X higher. Dips in the speaker impedance curve are not a problem and the AHB2 drives these cleanly.".

What's the problem?

I would like to thank John Siau a.k.a @gearbuilder for taking the time to provide detailed explanation and clarification. I appreciate the technical detail.

I have answers to my questions, apart from "damping factor" being halved I really do not see anything I am loosing by trying two AHB2 with each in bridged mono mode. My speakers can only dip to 3.8 Ohm minimum.

Sure two AHB2s may be overkill for my speakers but I will audition in both bridged and non-bridged mode now that I have all the information. Thanks to everyone.