buffers Vs unbuffered..

[boodi]

Hi , laughs allowed everytime i do a question here ( I'm the most un-diy fier probably

)

question : what buffers basically do ?
what an unbuffered design gain ( and loose ) vs amp with buffers ?

thanks

 

[Garbz]

buffers do a few things but one of the main reason we use them is because they pump out high current at unity gain into low impednace loads.

In english this basically means that a buffered amp has the current required to better drive low impendance heaphones like Grados which need them. However for high impedance loads not a lot of current is needed and buffers may usually be omitted.

 

[Voodoochile]

And a high-impedance can, while not requiring a lot of current, will require more voltage than a low-z can to sound proper.

 

[boodi]

ok
so..
why I see generally reported that the "headsave classic" amp mates very well with grado cans when it is supposed to be unbuffered ..?

 

[00940]

impedance figures by themselves don't mean much. They have to be put in relation with the sensitivity of the cans. A low impedance low sensitivity pair of cans could need more voltage than high impedance, high sensitivity headphones.

 

[nikongod]

Quote:

Originally Posted by boodi ok so.. why I see generally reported that the "headsave classic" amp mates very well with grado cans when it is supposed to be unbuffered ..?

that may be the "sonic character" of the amp stage used. a buffer is not even close too necessary to drive a grado very well.... i sold a aph-47 recently that got some rave reviews in private conversation... it does superbly on the ms-2's and it rocked my hd-595's. not 1 buuffer, just 2 dual opamps.

buffers are used primarily to isolate the amp stage from the load. there are quite a fiew opamp chips that dont particularly care for (hate may be a better word) a capacitive load, guess wat a LONG headphone cable looks like... a small cap. there is also sometimes a problem for amp chips to drive a vairying load. ie they drive diferently into 125ohms compared to 450ohms.... the buffer is "seen" by the amp stage as a constant load. the buffers do not typpically have this proiblem so long as the "minimum load impedance" is respected.

edit:
:read this too:

older thread

 

[Garbz]

also while buffers generally supply loads of current which is often heard as better driver control with more solid bass slam, each has it's own sound signature which may not be as good as an unbuffered amp.

Also technically the Aph47 is buffered. It uses opamps in unity gain as the buffer.