Does anybody know why they used class D for bass and AB for mid and treble ?

 

 

Purely technical I think. Due to the operating principle, class D amps get increasingly difficult to implement when the required audio frequency range gets higher. Also, the main advantage of class D is power efficiency, and most of the power is required at the bass section. Therefore, using class D for the higher frequencies as well would add a lot of cost and technical difficulties with practically no benefits.

And it is essentially the same chassis as that of the Beolab 1 so it needed no big design costs.

tournedos:

Therefore, using class D for the higher frequencies as well would add a lot of cost and technical difficulties with practically no benefits.

Interesting, what about 5's then ?

Is there any down sides with this setting D+AB ?

 

nmartin771:

tournedos:

Therefore, using class D for the higher frequencies as well would add a lot of cost and technical difficulties with practically no benefits.

Interesting, what about 5's then ?

Even the mid and treble amps are much bigger in the 5s, so I believe it is already a question of practical implementation issues... if it needed two uncompromised quality 250W conventional amps in addition to what is already in there, I think you would need a fork truck to move them around, and the amount of generated heat would be too much.

nmartin771:

Is there any down sides with this setting D+AB ?

None really. They are matched together and it's not an issue at the listener end

tournedos:

Even the mid and treble amps are much bigger in the 5s, so I believe it is already a question of practical implementation issues...

And possibly also a matter of prestige in using their own ICE-technology in their TOTL speaker?

BTW, great thread and great answers from tournedos - many people seem to think that class D is better than AB in all aspects, which it isn't. It's better in some, worse in others.

henrik:

And possibly also a matter of prestige in using their own ICE-technology in their TOTL speaker?

Interesting point ...

I'm not that technically educated, but can you go digital with mixed amplifiers ? D+AB

BL5 are all D and they have digital input.

 

There is no such thing as a digital amp. D in class D doesn't stand for digital. That notion is purely marketing. There has to be a DAC somewhere in the chain and there is no tech benefit of building it in in the speaker.

The main benefit of class D is effiency. AB is soundwise equivalent and even better when it comes to high frequencies.

The design choices in both bl5 and bl9 makes sense from a tech perspective.

Style:

The main benefit of class D is effiency. AB is soundwise equivalent and even better when it comes to high frequencies.

hm ... Does it mean that class D mid's and high's in to BL5 are there for "purely marketing" reason ?

Or it is not "audiophile correct" to sell 18K speakers D+AB ?

I think the Ds are there because 250 watt AB would weigh a ton and you would need cooling the size of a fridge, ie they are their because they are efficient

Style:

I think the Ds are there because 250 watt AB would weigh a ton and you would need cooling the size of a fridge, ie they are their because they are efficient

My thoughts exactly.