August 28, 201015 yr Got word that my LCD-2's should ship this coming week. Congratulations, you bastard
August 29, 201015 yr AMB Laboratories DIY Audio • View topic - Benchmark Engineer on Balanced v Unbalanced Headphone Amps I knew there were benefits, I just couldn't remember what they were or how relevant they are. I'm guessing it's a toss-up between making an SE amp that needs higher rated components or just doubling everything to get the same net result. I wonder sometimes if, say, Little Dot didn't go with a balanced MKVII simply because it was cheap to just use 4x a very basic OPAMP-based circuit for this reason. I saw some Dynahi discussion there too, with mention of balanced operation, gain, stability and low-impedance cans. Is doubling everything essentially double the voltage swing, or does it affect current as well? I'm thinking specifically of, say, HD-800s vs. LCD-2s with amps here.
August 29, 201015 yr Is doubling everything essentially double the voltage swing, or does it affect current as well? I'm thinking specifically of, say, HD-800s vs. LCD-2s with amps here. It doubles the voltage swing since one channel is inverted, but doubling of output current is up to the task of the amplifier, since each channel sees half the load impedance. The actual amount of power that can be transferred into the load depends on the relationship between the output impedance of the amplifier and the impedance of the headphones. I'm just going to put out there that I think matching the relatively low impedance LCD-2 with a 400 or 800 ohm output impedance amp is a terrible idea and is incredibly inefficient, with most of the power dissipated in the amplifier instead of the headphones, not to mention the damping factor is nonexistent. Edit: Though I guess maybe you could consider it a current source amp?? Edited August 29, 201015 yr by mypasswordis
August 29, 201015 yr Yeah, low output impedance and high damping factor are a must with any planar driver. Just don't try to tell that to the idiotic fanboys...
August 29, 201015 yr What amp(s) have a 400 or 800ohm output impedance? I'm going to guess that it's some sort of tube amp?
August 29, 201015 yr My bad, I remembered damping factor as output impedance from that link kwkarth posted a few days ago: Audeze LCD-2 Orthos - Page 266 - Head-Fi.org Community Yeah 400 or 800 is high even for OTL, was wondering how that worked. iirc the Wheatfield HA-2 is 100+ ohms.
August 29, 201015 yr Yeah, low output impedance and high damping factor are a must with any planar driver. Just don't try to tell that to the idiotic fanboys... damping factor is more important for orthodynamics then dynamics or vice versa? Most say it
August 29, 201015 yr Well the push-pull nature of the planars should make it less important but the large diaphragms do need a lot of damping so lets just say damping factor is important.
August 31, 201015 yr It doubles the voltage swing since one channel is inverted, but doubling of output current is up to the task of the amplifier, since each channel sees half the load impedance. The actual amount of power that can be transferred into the load depends on the relationship between the output impedance of the amplifier and the impedance of the headphones. I'm just going to put out there that I think matching the relatively low impedance LCD-2 with a 400 or 800 ohm output impedance amp is a terrible idea and is incredibly inefficient, with most of the power dissipated in the amplifier instead of the headphones, not to mention the damping factor is nonexistent. Edit: Though I guess maybe you could consider it a current source amp?? Thanks for the summary. I figured, say, OTL amps were out. I know that much at least. I feel I need to get a better handle on how amp specs relate to suitability to driving headphones. The spec pages for various amps seem to be very random in what is shown and what is not, however. I'm also trying to derive a useful understanding of what the bias adjustments on my amp actually do, if not just increase the bias voltage.
August 31, 201015 yr I thought output impedance didn't really effect the FR of orthos because they're resistive, and it was power output that mattered?
August 31, 201015 yr It doesn't affect FR that much because indeed orthos are almost purely resistive and thus have a flat impedance plot, but it affects damping. Contrary to the waterfall plots Audeze posted and even Tyll measured, I thought the bass was a bit bloated so having an iron fist control over the bass in the form of low output impedance amp would be necessary for me. Also, don't forget, amps don't necessarily have very flat output impedances either.
August 31, 201015 yr I'm also trying to derive a useful understanding of what the bias adjustments on my amp actually do, if not just increase the bias voltage. Throw everything out of whack? At best it increases supply power to the chips, likely increasing its bias into class A. At worst throws off calibrations and sends the chips into cascading spiral. Long and the short of it... if you aren't running out of power... don't overclock your amp =P
August 31, 201015 yr I was rather confused when I read the "balanced amp" discussion portion. I know the basics of balanced operation, but much of what he said just made me confused. That post from Benchmark is the perhaps the worst post on the subject I've ever seen. It is basically exactly wrong, and suggests that Benchmark has no idea how to drive headphones. In general the distortion goes down, not up. As long as both sides are well matched. impedance does go up, but compared to the impedance of the wire feeding the headphones it makes little difference for things like dynahi,b22. slew rate doubles. noise cannot be determined, but probably goes up. There is a distinction to be made between balanced and differential. All differential amps are balanced, but not all balanced amps are differential. Differential amps (unlike the standard balanced amps that are really two SE amps back to back, and that offer little to no benefit for headphones) isolate AC from DC, and keep the signal current loops away from things like the power supply, and PS caps. There is no reference to either B+ or ground, and thus little to no noise. There is a blurb on it at Vacuum State (on page 3): http://www.vacuumstate.com/fileupload/RTP3D_brochure_b.pdf damping factor is more important for orthodynamics then dynamics or vice versa? Most say it
August 31, 201015 yr unlike the standard balanced amps that are really two SE amps back to back, and that offer little to no benefit for headphone
August 31, 201015 yr ordered june 16th...just got the e-mail & paid today... Got my email too. Thought I hadn't but the damn thing went into my spam pile.... Edited August 31, 201015 yr by Absorbine_Sr I'm a eejit.
August 31, 201015 yr anyone ever heard a phillips david?? Probably way before most of your times... But it would be interesting to put a capsule mic inside the audeze, and do active balancing of frequency response with feedback just like the phillips did. Turn the thing ruler flat in a jiffy. Would be super easy as the thing is a dipole.
September 1, 201015 yr Now now Kevin, KW proclaimed the LCD-2 gods gift to audio and that the smaller the tube the more bass it produces
September 1, 201015 yr what does that moron's opinion have anything to do with the price of tea in china. I really like the lcd2, but there are things that i don't like also. Some of those resonances need some work. And besides, motional feedback sure seems like a great and easy thing to do with dipoles... These guys could learn a lot from how magnaplanar does stuff.
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