Audeze LCD-2

[mypasswordis]

Output power and class A biasing aside, I'm not sure how well a warmer smoother sound would work with the stock LCD-2. Maybe output BJTs would be better, so try a Dynahi or PPAv2 if you can find one?

But if you still have your balanced M3, definitely try it out.

[Beefy]

It sounds like I should retain the M3 that I currently have then (at least for a while), and budget up for a B22 in the future. I was also looking at the Dynalo specs but couldn't conclusively tell if it'd be able to properly drive the LCD-2, but given the current output you stated, it seems like it too would be inadequate?

From what I can find, the dynalo runs 50-60mA by default, so less than the M3. I don't think it can go much further, because heatsinking is difficult.

a CK2III can be biased deeper into Class A, but offboard heatsinks would be a must. the fact that the BJT output transistors have a positive temp coefficient would make this a little more tricky (thermal runaway) than compared to the negative temp coefficient of the output MOSFET transistors in the M3. if you wanted a little more headroom than the bog standard M3, just get taller on-board heatsinks and bias deeper into Class A. the M3 is an excellent and economical amp to drive piggy loads.

60mA max with heatsinks, according to AMB's website. Still about half what a well-heatsinked M3 can handle.

But yeah, as MPI says I can't account for the sound. I've only heard the M3, and only with a few phones.

[Beefy]

It sounds like I should retain the M3 that I currently have then (at least for a while), and budget up for a B22 in the future. I was also looking at the Dynalo specs but couldn't conclusively tell if it'd be able to properly drive the LCD-2, but given the current output you stated, it seems like it too would be inadequate?

From what I can find, the dynalo runs 50-60mA by default, so less than the M3. I don't think it can go much further, because heatsinking is difficult.

a CK2III can be biased deeper into Class A, but offboard heatsinks would be a must. the fact that the BJT output transistors have a positive temp coefficient would make this a little more tricky (thermal runaway) than compared to the negative temp coefficient of the output MOSFET transistors in the M3. if you wanted a little more headroom than the bog standard M3, just get taller on-board heatsinks and bias deeper into Class A. the M3 is an excellent and economical amp to drive piggy loads.

60mA max with heatsinks, according to AMB's website.

[Asr]

Sound? Who cares about sound? All I care about is matching specs.

[fishski13]

i don't mean to turn this into an op-amp rolling dork-fest, but if you're concerned about the M3 being too warm with the LCD-2, the OPA627 are supposedly warmer sounding than the default AD8610. i've only tried the AD8610 and AD8065, with a preference for the AD8610.

[mypasswordis]

It's cool, tangent's got that covered. Notes on Audio Op-Amps

Just found the huuuuuuge thread on diyaudio about vertical/lateral MOSFETs vs. BJTs on diyaudio. Gonna take me a couple weeks to read through and understand.

[fishski13]

It's cool, tangent's got that covered. Notes on Audio Op-AmpsQUOTE]

an excerpt: "The higher bandwidth of the 637 results in a somewhat more lively sound than the 627. It still has the overall laid-back Burr-Brown characteristic, though."

my inner-dork is truly humbled.

[Smeggy]

I wear my inner dork on my sleeve.

[jcx]

using 50 Ohm, 91 dB/mW requires +/-10 V, +/- 200 mA peaks to reach 120 dB SPL

some people may be happy at 1/2 the I,V for "only" 114 dB SPL peak at clipping - as push-pull Class A which can deliver up to 2x the bias currrent the DynaLo and M3 should manage this lower power

the M3 "3-channel" active ground can't sink both R,L channel peak current in Class A, but a properly set up 36-40 V supply M3 should be able to drive the LCD-2 to 120 dB SPL as long as you don't mind the idea of the output gnd channel Mosfets running Class AB on (rare) peaks

do remember that the stadard AD8610 op amp in the M3 can't take higher supply V and should be swapped to opa604

[mypasswordis]

I think I would mind damaging my hearing before the idea of running in Class AB at 120dB. But headroom is always nice.

[jcx]

do I have to go into dynamic peak headroom details here too? - the other place I've come to expect such inanity

[mypasswordis]

I'd try to retort, but you probably wouldn't be able to hear me.

[Nebby]

Hmmm....120db? Can you hear me now?

[jcx]

iPods will drive the LCD-2 to 100 dB SPL - so why so much discussion in this thread about amps?

[Grahame]

I'm guessing the correct answer would be to plot SPL vs THD using the LCD-2 as the transducer in Tylls Headphone measurement lab, comparing the iPod vs amped iPod as source.

[mypasswordis]

THD is only one part of it. Someone clearly doesn't understand the purpose of amps.

[morphsci]

iPods will drive the LCD-2 to 100 dB SPL - so why so much discussion in this thread about amps?

Warning! Warning! alert!

[deepak]

jcx isn't an he has designed a nice amp I remember hearing it many years ago at a Boston meet.

[morphsci]

^^^ Those two things are not mutually exclusive, but I will take your word for it

[deepak]

^^^ Those two things are not mutually exclusive, but I will take your word for it

True, I guess I was implying that I met him as well, but I can understand if that didn't come across in my post.

Dynamic peak headroom doesn't mean you're listening at 120 db sustained. There are instruments like a concert grand that can hit 120 db peaks, in short attacks this will not hurt your hearing. I would think designing an amp means you know the purpose of an amp

Edited July 25, 2010 by deepak

[Beefy]

There are instruments like a concert grand that can hit 120 db peaks, in short attacks this will not hurt your hearing.

In short attacks, you probably won't notice crossover distortion either.

[mypasswordis]

Dynamic peak headroom doesn't mean you're listening at 120 db sustained. There are instruments like a concert grand that can hit 120 db peaks, in short attacks this will not hurt your hearing.

There's no way in hell a concert grand reaches 120dB. The performer would long go deaf, especially if he/she is any good and practices 8-10 hours a day. That's not even considering the fact that you're supposed to be in the audience. Also 120 dB peaks means what, around 100dB "normal" volume? And that's for well recorded material. You've got to be shitting me.

I would think designing an amp means you know the purpose of an amp

Apparently you're wrong.

[luvdunhill]

I would have guessed 100 dB peak at say 12-15 feet away from a piano. That's a rare case though, and probably 90 dB peaks is more common. 120dB seems high to me.

I'd be curious to see some data though.

[mypasswordis]

Take a Survey: How many decibels is your piano? - Piano World Piano & Digital Piano Forums

[deepak]

There's no way in hell a concert grand reaches 120dB. The performer would long go deaf, especially if he/she is any good and practices 8-10 hours a day. That's not even considering the fact that you're supposed to be in the audience. Also 120 dB peaks means what, around 100dB "normal" volume? And that's for well recorded material. You've got to be shitting me.

Apparently you're wrong.

There is a planar thread on AA and someone has measured their grand hitting 120 db at the peaks in their room. Followed by the usual postings about how electrostats aren't suitable for loud classical.

How am I wrong about the second part? Based on a tongue in cheek post about the ipod driving the Audeze?