[CaptainZeb]

Hello everyone. It's a first time posting for me.

What are everyone's thoughts about powering Grado PS1000e or PS500e with a OTL amp with an output impedance of 15 ohms.

I'd also like to give the Audeze LCD-X a shot, but they have an even lower input impedance than the Grado's at 20 ohms. Most of the other planar headphones I've listened to are to dark for my tastes.

Thanks for your input.

 

[ProtegeManiac]

What are everyone's thoughts about powering Grado PS1000e or PS500e with a OTL amp with an output impedance of 15 ohms.

I'd also like to give the Audeze LCD-X a shot, but they have an even lower input impedance than the Grado's at 20 ohms. Most of the other planar headphones I've listened to are to dark for my tastes.

Your best bet is to find somebody that owns the exact same headphones and uses them with that exact same amplifier because damping factor issues due to output impedance is hard to predict, ie, it can result towards or outright bloat, or it can be a tin can. Every amp (that includes all other amp types with the same issue) and headphone combo can be very different than if it was a different amp and with the same headphone or vice versa. There's a way to kind of predict but when it was explained in this forum it was so highly complex I'd much rather just get past the damping factor issue with low output impedance to begin with.

The LCD-X might still be less affected but planars aren't totally immune once the output impedance is already higher than the load impedance.

 

[tomb]

IMHO, an OTL amplifier is simply not going to have enough power to properly supply planars. There are a lot of non-OTL amps that have trouble with them, too.

However, it may do quite well with your Grados. Even though Grados are low impedance at 32 ohms, they have high internal damping. They actually perform better with a little higher impedance on the output of an amplifier. It's one of the reasons why Grados can sound very harsh on a modern, super-low output impedance amplifier. A tube amp with output transformers are ideal. Something like a Mapletree, Bottlehead Mainline, or an ECP Audio product (I'm totally biased on that one), can be an endgame with them.

 

[CaptainZeb]

Thanks for the responses.

My local Grado dealer (300 miles away, lol) agreed to let me bring my amp in so I can try it out with a few different Grado headphones, so we'll see how that goes.

Maybe once I have my new phono preamp put together, I'll start on a tube headphone amp with some output iron for my next project.

 

[ProtegeManiac]

I'd also like to give the Audeze LCD-X a shot, but they have an even lower input impedance than the Grado's at 20 ohms. Most of the other planar headphones I've listened to are to dark for my tastes.

Forgot about the highlighted part last time.

If you find planars dark it might be due to degenerative high frequency hearing loss, and while many planars tend to have a flatter response, that's not across the entire range. Some like the LCD-2 and to a lesser degree the LCD-2F are flat below 800hz, then drops, then are relatively smooth above 2000hz. LCD-3 isn't too far off that, just enough that the immediate impression for most people is that it's an improvement over how dark the original LCD-2 is. Newer HiFiMans tend to be flat below 1000hz, but then the HE400(i) (does not include the S) tend to take a nose dive somewhere in the midrange to treble transition then back up to peaks in the treble, however what might sound like peaks to those with normal hearing might not be enough to compensate for the weaker upper midrange response. It can sound flat in terms of being a compensation curve for human hearing, but it can be a problem if you have degenerative high freq hearing loss.

If you'd try a planar the HE400S might be your best bet, however its response is closer to a dynamic headphone overall (albeit the better dynamics), with the planar advantage being that its low end is very clean even without a high power, high current, low impedance/high damping factor amp, with high sensitivity and low impedance. In short...think of it as more like getting an HD600 that's even less picky with amplifiers (ie a decent, under $200 portable amp can work well with it as a transportable).