I can't explain it well, the diference is simple wen we spell about decibels we are spealling about a logaritmic scale, but wen we spell about DBA we are refering to a phisic unit an their scale mode(0 DBA = is a presure of 0.2 nanobars), we can refer it to DB, but this can make confusion for this I used the DBA name, both are corrects but this is more clear.

read this explanation, is very simple but veri good: http://www1.jaycar.com.au/images_uploaded/decibels.pdf
this is a more estense explanation:
http://www.jsdsound.com/decibels.htm

Thanks for the urls

BTW I have been browsing for some hot subwoofers, I found this one http://www.yamaha.com/yec/products/HXseries/YSTSW1500.htm seems very pleasant but i've read something unusal on the power specs it says

''Highly efficient power supply
Extremely efficient amplifier''

1. How can an amplifier of this power range (1000watts) be efficient ?

2. What class would this amplifier be then ?
C perhaps, if yes then quality wouldn't really be that much, would it effect bass that much ?


3. Does the use of coolers ,heatsinks etc increase power efficiency ?





Thanks

the amplifier at any power can be eficient, this amplifier can be a class AB derivatted type class "F" ( this is a high eficient class compared to class A and class AB ) or a class D amplifier, the class D is the most efective and the class C is not used in audio, only is used in the high frecuence donain ( radio, tv... ). Class D in the past don't have the quality of a class A or clas AB and derivateds but now the class D have a very proximun quality or the same quality but this is more relative to devices than to the class. the coolers, heatsiniks don't increse the eficiency but they ared need to maintain the componets cooler, the amplifiers had avery big heat dissipation but how more efficient is less heat dissipation have it, and if you dont use it the amplifiers can be literaly burn their components.

Class F and AB ?

Whats the difference between them ?

sorry I mismacth an i refer to calss G to E and class H to F

old posted link here over amplifiers tipes.
http://www.screensound.gov.au/glossary.nsf...er?OpenDocument

I mean something that lives up to the expectations of the most exigent audiophiles.

Thanks guys.

Does bridging stess the amplifier ?