Bridging an amplifier


I recently watched a YouTube video, a few years old, that featured Flemming Rasmussen, the highly regarded founder and engineer for Gryphon (now retired I believe). Flemming was speaking of his class A monoblock amplifiers in the Antileon Evo, Colloseum and Mephisto. Flemming was expressing his disdain for Monoblocks that are actually 2 internally bridged amplifiers, (such as DNA 500,Clayton M300s and also class A Luxman that can be used as Monoblocks in the BTL mode (bridged tied load), calling these types of Monoblocks inferior and not true Monoblocks. He claims dedicated Monoblocks where all push pull transistors are paralleled, are vastly superior to summing the two channels via bridging (antiphase summing). I’d love to know if most audiophiles and engineers agree with Flemming. I have owned and found both the DNA Monoblocks and Clayton M300 Monoblocks to sound excellent, and a friend uses two M-800A Luxman class A amplifiers in bridged tied load mode (BTL switch) with great clarity and power. Thank you for your thoughts!
audiobrian
audiobrian
Flemming was expressing his disdain for Monoblocks that are actually 2 internally bridged amplifiers

Flemming is right, and these are these are the reasons for not bridging amps.


  I’ve said it before in other threads here it is again

"Nice amp, if you want to hear them at their best, don’t bridge "if there’s no need to", as all you’ll gain is watts, everything else takes a hit when you bridge amps.

Pro’s=
More watts.

Con’s=
Worse damping factor
Higher output impedance (has relevance to damping factor)
Lower stability (especially into low impedance’s)
Current ability is reduced (especially into low impedance’s)
Higher distortion.

And if you have two of them better to run them in stereo mode and vertically bi-amped, instead of bridging (mono’ing).
http://www.av2day.com/wp-content/uploads/2014/05/biamp2.jpg"

Cheers George
First of all Rasmussen is not an engineer. I believe his degree is in graphic arts. He is a very rich old audiophile who had nothing else do do with his money. Wonderful, any way great audio equipment comes to life is fine by me.
Although I am ace with a soldering iron my knowledge of electronic engineering is basic at best. I only know what I hear. With the exception of the Benchmark AHB2 I have not heard a bridged amp sound as powerful as a dedicated mono amp of similar power. The Benchmark is an enigma. This is on ESLs , planars and subwoofers. 
Hi George:

Thank you again for your ‘input’.  I’m just wondering why designers/engineers from Constellation, Naim, Clayton, McCormack and other fine manufacturers, who obviously are aware of these compromises, choose to use balanced bridged designs in their reference products. Do you believe their decision is based partly on cost, generating maximal wattage without the robust power supplies and output stages needed to generate 200 wpc in a non bridged, high current, class A design?  Interesting...thanks again!
It's all out there to search, Al has also given some good info on it as well, above. If all you need is watt's then bridging is the way to go. 

Cheers George
I own both dedicated mono design amps as well as 2 channel amps ive bridged into a single channel, i even have a pair of monoblocks whos design is a 2 channel amp that's internally bridged at the factory and sold in singles as a mono amp ,ive found no design to be superior , for my ears much depends on synergy between amp & preamp as well as proper impedance matching monoblocks to the load a speaker presents at its lowest part of the curve ,case in point ,on my 8 ohm speakers my best sounding monoblocks are a pair of Mcintosh Mc-252s bridged for 500 watt @8 ohm amps when compared to my 1200 8ohm watt factory designed Mcintosh Mc-1201 monoblocks , with 4 ohm loads my factory bridged Emotiva XPR-1 monoblocks blow the pants off of the Mc-252s i run in mono as well as the purpose built Mc-1201s & Jeff Rowland true monoblocks , with my maggies my class D true monoblock Jeff Rowland amps sound better than my other amps, even better than the 2 channel amps i cannot bridge , i do believe the guy who wrote the article has went a bit off the deep end .