Thoughts on using LCD-3 with S.E.X 2.1 with C4S and Impredance Switch Upgrade

[Adamaley]

Hi guys. I posted this over on the Head-Fi forum as well, so I'll just copy and paste here.

I am in dire need of some solid, quick, well-informed advice, and my question is two-fold. Firstly, I am looking to acquire a Bottlehead S.E.X amp, but really need to know anyone's experience with it driving the Audeze LCD-3. I understand that an informed guess will suggest that it should be able to. There are many accounts of it driving the LCD-2.2s with aplomb, which is a healthy sign. I plan on using this combo until after CanJam, after which I will look to upgrade amp-wise.
 
Which leads to the second part of my question. After I acquire an upgrade amp, I'll ultimately be looking to use the S.E.X with either the Paradox Slants/Alpha primes (or one of the closed non-TOTL planars). I believe theses should be easier to drive than the LCD-3s, but please feel free to chime in.
 
NB- I'll be looking to get the fully upgraded amp @ Version 2.1 w/ C4S & Impedance Switch
 
Thanks in advance.

[Paul Birkeland]

From the Audeze website, they say 1-4 Watts will work nicely, and the headphones are 110 Ohms.

What one must wonder, is whether that is 1-4 Watts from a solid state amplifier rated for 8 Ohms, or if it's actually 1-4 Watts at 110 Ohms.  In either case, you're totally covered with the SEX amp.  Using the impedance switch kit, you can go from 4 Ohms out (this would be good if the LCD-3's are more sensitive than expected) to 32 Ohms out with the flick of a couple of switches.  2 Watts at 32 Ohms would yield about 8V out of the SEX with a 32 Ohm load.  With a 110 Ohm load, that voltage will creep up quite a bit, which ought to help a bit.

It is worth mentioning that a typical solid state amp rated for 4 Watts at 8 Ohms will make about 280mW into a 110 Ohm load.  Audeze lists the LCD-3 at 93dB/1mW sensitivity, so 280mW would get you to 118dB (real loud!).  Their 15W peak rating also roughly pops you over 120dB if you assume that 15W rating is for an 8 Ohm load.

[Adamaley]

Thanks for the response, Caucasian Blackplate. I forgot to specify that I have the LCD-3 Classic, which has a lower impedance of ~50. Would your post apply to this version as well?

[Paul Birkeland]

You'll get nearly 2W into 50 Ohm headphones on the 32 Ohm tap, so I think you'll be in even better shape. 

-PB