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Good tube amp to run both Grado sr325 and HiFiman HE 300? Recommendations? - Page 3

post #31 of 58
Quote:
Originally Posted by zackk View Post
 

Thank you.

 

Now I know with speakers.. the lower the Ohm #, the "lower" the impedence/more dificult load/less efficient/less sensitive.

 

So how come 300-600 ohm headphones seem to require more power than lets say... 32 ohm grados?

Shouldn't the higher ohm headphones need less power?


The MKIII is an OTL tube design, so it puts out more power into higher impedance loads. This is somewhat of an exception among amps -- most other designs put out less power into higher impedance. I think the perception that high impedance headphones require more power has to do with the fact that many amps (pretty much all solid state amps, for example), put less power into high impedance headphones. So an amp with plenty of power for low impedance headphones may have a harder time driving high impedance headphones. It's the other way around for the MKIII however -- the MKIII is best suited to high impedance headphones. It can still work with some low-impedance headphones headphones of course, but it may not be ideal. Grados have such high sensitivity that they should be fine, but I can't say for sure.  

The impedance of a headphone doesn't tell you much by itself. You also need to look at sensitivity. If you have two headphones with the same sensitivity but different impedances, both would require the same power to reach a given volume. However, the high impedance headphone would take more voltage and less current, and the low impedance headphone would take less voltage and more current. 

There is also the issue of damping factor. The output impedance of an amp forms a voltage divider with the impedance of the headphones. Since dynamic headphones typically have changing impedance at different frequencies (that 32 ohm figure was probably measured at either 500hz or 1000hz), they will get different amounts of voltage at different frequencies. To keep this voltage fluctuation low enough that it doesn't affect frequency response by more than 1 dB or so, it's recommended that the output impedance of an amp be 1/8 or less of the nominal headphone impedance. I asked David at Little Dot about the output impedance of the MKIII and he only said that it's "less than 10 ohms." This isn't exactly confidence-inspiring. That ratio I mentioned could be anywhere from ~1/3 to well under 1/8 for your 32 ohm Grados. Perhaps Frank has a more precise measurement that would be helpful...

EDIT: The output impedance changes at different gain settings. See post #10 here http://www.head-fi.org/t/272595/question-about-little-dot-mkiii-gain-settings


Edited by manbear - 1/6/14 at 10:16am
post #32 of 58
Quote:
Originally Posted by Frank18944 View Post
 

boring and tedious.

 

Read my last post - the HD-400 will go to  113 dB with the LD MK3 and that by anyone's standard is loud.

 

Have a nice life dude.


If you use voltage based calculations and take gain and source voltage into account, you will get different results, as I already mentioned. I will also remind you that only parts of the music, such as bass transients, need to exceed the threshold for clipping. Music can clip at peaks when the average SPL is much lower. With high-dynamic range music, this is easier than you seem to think.

It doesn't really matter. I've heard the Little Dot clip into the HE-400 and people can decide for themselves if they'd rather believe someone with direct experience or if they'd rather believe someone who still can't even spell the headphone's name and who displays a breathtaking level of butthurt when someone offers a contrary viewpoint. I've read all of your posts and they don't settle the matter as decisively as you have apparently convinced yourself. 


Edited by manbear - 1/6/14 at 11:43am
post #33 of 58
Thread Starter 
Quote:
Originally Posted by Frank18944 View Post

boring and tedious.

Read my last post - the HD-400 will go to  113 dB with the LD MK3 and that by anyone's standard is loud.

Have a nice life dude.

I don't even care either way the argument goes... Just grow up and stop posting about it here if you're going to get in a hissy fit.
post #34 of 58
Thread Starter 
Quote:
Originally Posted by manbear View Post


The MKIII is an OTL tube design, so it puts out more power into higher impedance loads. This is somewhat of an exception among amps -- most other designs put out less power into higher impedance. I think the perception that high impedance headphones require more power has to do with the fact that many amps (pretty much all solid state amps, for example), put less power into high impedance headphones. So an amp with plenty of power for low impedance headphones may have a harder time driving high impedance headphones. It's the other way around for the MKIII however -- the MKIII is best suited to high impedance headphones. It can still work with some low-impedance headphones headphones of course, but it may not be ideal. Grados have such high sensitivity that they should be fine, but I can't say for sure.  


The impedance of a headphone doesn't tell you much by itself. You also need to look at sensitivity. If you have two headphones with the same sensitivity but different impedances, both would require the same power to reach a given volume. However, the high impedance headphone would take more voltage and less current, and the low impedance headphone would take less voltage and more current. 


There is also the issue of damping factor. The output impedance of an amp forms a voltage divider with the impedance of the headphones. Since dynamic headphones typically have changing impedance at different frequencies (that 32 ohm figure was probably measured at either 500hz or 1000hz), they will get different amounts of voltage at different frequencies. To keep this voltage fluctuation low enough that it doesn't affect frequency response by more than 1 dB or so, it's recommended that the output impedance of an amp be 1/8 or less of the nominal headphone impedance. I asked David at Little Dot about the output impedance of the MKIII and he only said that it's "less than 10 ohms." This isn't exactly confidence-inspiring. That ratio I mentioned could be anywhere from ~1/3 to well under 1/8 for your 32 ohm Grados. Perhaps Frank has a more precise measurement that would be helpful...


EDIT: The output impedance changes at different gain settings. See post #10 here http://www.head-fi.org/t/272595/question-about-little-dot-mkiii-gain-settings

That was extremely clear and helpful, thank you!
That last bit confused me a little but that's ok haha
post #35 of 58

So this thread got a little fixated on the Little Dot MKIII. I don't think this would be a terrible choice. You could easily be happy with it. But there are other options. Unfortunately, I haven't heard any of them and can't really comment on the sound. 

Here is one amp that might be worth looking into: http://www.garage1217.com/garage1217_diy_tube_headphone_amplifiers_002.htm. You can set the output impedance to 1 ohm, so damping factor won't be a problem with Grados. It says DIY, but you can order pre-built amps for a little bit extra. 

 

For more money, this is a popular transformer-coupled tube amp: http://wooaudio.com/products/wa6.html. OTL means output transformer-less. The lack of a transformer is what makes OTLs best suited for high impedance headphones -- they are better at putting voltage into high impedance headphones than putting current into low impedance headphones. A transformer coupled tube amp would be more optimal for low impedance headphones. 

A few other things to note after re-reading your first post:

You said you heard your Grado through tubes and you liked it -- what amp was that? Why not just get that one, since you've heard it and you know you like it? 

I don't think the company Darkvoice is still in business. AFAIK, the company Lafigaro now makes the same amps. EDIT -- I'm not 100% sure about this. These Chinese companies are confusing. I can find "Darkvoice" amps on Ebay, but I can't find the Darkvoice company anywhere. But if you don't want to buy from Ebay, Lafigaro is the only company that actually has a website that I can find. 

The HE-300 isn't a planar headphone. It has dynamic drivers. The HE-400 is the cheapest planar headphone made by Hifiman. The Fostex/ variations are the cheapest planars I know of. Also, as far as Fostex goes, everyone talks about Mr. Speakers Mad Dog, but you might want to look into the ZMF modded version. It is cheaper and some people like it better. I have no idea though. 

I would also give hybrids another chance -- read some reviews and see if they will have the sound you are looking for. The LD 1+ has plenty of fans. The reasoning here is that most cheap tube amps that are optimal for low-impedance headphones will be hybrids. You could even connect a tube DAC like the Aune T1 to a hybrid amp to get double tubeyness. 


Edited by manbear - 1/6/14 at 4:57pm
post #36 of 58
Thread Starter 

I heard the Grado sr325 through tubes when I got my new preamp, an Audible Illusions Modulus 2C. However it has no headphone jack, so I ran the outputs into my Van Alstine preamp and used that headphone jack. It sounded much better than before with both the Pro-Ject HeadBox II and from just the VA preamp.

 

I would love the Woo Audio hp amp, but that's way out of my range. I also want to avoid the kit ones because I haven't had time to teach myself to solder, and I also want to avoid the exposed amps like Project Sunrise, Muse, Bravo or Indeed, and the like. I had the Little Bear one, and whileI know it is on the lower end of the spectrum... I was very unimpressed. Also, I want something that has more build quality and looks like it will belong in my system.

 

The Darkvoice ones definitely interested me as well. But from what I have read on this site, the stock tubes aren't as good out-of-the-box as the little dot tubes.

The Valhalla would be ideal. Great build quality, customer service, good looking, reliable. ect. I need to look used though for that, or even the Music Hall 25.2 headphone amp.

 

I would consider hybrid if the sound is still tube-like and smooth. What other options are there, hybrid or all tube, well known or lesser known? I keep seeing used Yarland p-100?

 

The Fostex t50rp stock, I was very unimpressed with. I know with speakers and components, interconnects and speaker wire has never made a noticeable difference to the quality of music... Those mods that ZMF has listed seem to mostly be wires and comfort related. I figured again, the wires changed in headphones wouldn't change the quality as it didn;t with speakers. Is it different with headphones and speakers? Do these mods actually make a noticeable improvement, which would definitely be needed for me to enjoy the Fostex cans. Are the mods similar between ZMF and Fostex?

post #37 of 58

Interesting. I'm guessing you want a headphone amp instead of just continuing with that chain of two preamps for convenience? Here is one idea -- get a hybrid and if it's not tubey enough for you, run it from your Modulus 2C. It's not at all necessary to use a preamp with a headphone amp, but hey, why not. You'd get double the tubes. 

The difference between all tube amps and hybrids is that there are two kinds of all tube amps -- transformer coupled and OTL. In general, a transformer coupled design or a hybrid is better for low impedance headphones. Of course, you might like an OTL just fine. Here is something interesting I saw on the for sale forum: http://www.head-fi.org/t/698359/mg-head-dt-with-nos-green-sylvania-12ax7 IDK about the sound as I haven't heard it, but you can switch between transformer coupled mode and OTL mode. That's a very interesting feature. There is also a person on the for sale forums right now selling a Schiit Lyr for $370. And here's a Music Hall 25.2 http://www.head-fi.org/t/690858/music-hall-ph25-2-headphone-amplifier The great thing about buying used here is that you can sell for about the same price you paid if you don't like it.  


I think for both the ZMF and Mad Dog mods, a lot of the difference in sound vs the stock Fostex has to do with damping materials added inside the cups. I wouldn't think wiring would make much difference. I think the main point of the rewiring is the option of balanced wiring if you have a balanced amp. 

For the Darkvoice amps, IDK about the quality of the stock tubes, but check the tube prices online. Some tubes are very cheap. I know the Little Dot tubes are. 

post #38 of 58
Thread Starter 
Which of those three amps would you pull the trigger on?

Thanks for all the replies. You've been a huge help!
post #39 of 58

Hmm. It's hard for me to really say, as I haven't heard any of those amps. Personally, I'd get the MG Head. Easy for me to say though. 

The Lyr is obviously a popular and well-respected amp, but that seller has no feedback. Plus the Lyr has 6W into 32 ohms, which is soo, soo much more power than you need. You might have a hard time using the volume knob. However, output impedance is less than 1 ohm, which is important for low-impedance headphones. I also know that tube rolling for the Lyr is expensive. 

The Music Hall has a tube pre-amp section and solid-state amp section. I think some reading would be required to make sure you hear the tubes with a source and headphones plugged in (e.g. make sure the tube isn't only in the chain if you just use it as a preamp). IDK exactly how it works. 

That MG Head is cheap and hence less risky of a purchase (plus it's the only one of the three that isn't a hybrid), so I'd probably go with that one. Switching between OTL and transformer mode is a really cool feature to play with too. I haven't heard it and it's a little on the obscure side, so IDK about SQ, but that's more or less the same risk you're facing with all these choices. 

post #40 of 58
Thread Starter 

I looked into the MG Head a bit more, and the version of the one you linked me to is not the OTL switchable one I don't believe, also missing a power chord. Correct me if I am wrong!

 

I saw the Lyr has 6 watts output, so yeah that might be way too much for Grados... that could power some horn speakers!

 

I saw a review of the Music Hall amp, ad the tubes are in stage with the headphone amp as well as the preamp section, so that's good. Also seems to be un-tubelike in sound, more flatter and solid state like. The tubes in those seem incredibly tiny... upon first look of the internals I almost couldn't find them.

post #41 of 58
If you prefer the warm, tubey sound the Valhalla might not be the best choice. Stock it sounds quite neutral. It definitely feels more like a ss amp with the stock tubes. Tube rolling might be nice in it and it would definitely work with your grados.

The build quality on the Valhalla is great. It's very solid, decently heavy and has almost no noise. Unless you crank it past 3 o'clock then it's pretty good usually. The brushed aluminum finish feels great and looks fantastic.
post #42 of 58

Yeah, don't let me push the MG Head on you. I did some googling around, and it seems like there are a lot of different versions. I thought the switch on the front was the OTL/ transformer mode switch, but I found a picture of one that looks almost the same and has two headphone jacks, one labelled OTL and one labelled Transformer (like this http://home.earthlink.net/~ivol/audio/reviews/asl/). So you are probably right. I'm not really sure. Best way to found out would probably be to PM the seller. Power cord is an easy fix though -- almost all amps use the same type of power cord and you can buy one cheap. It's probably the exact same type of power cord you would have on a desktop computer for example. 

If that is just the OTL version, you might as well put the Little Dot MK3 back in the picture. LOL. This looks like the one in the picture, and it says low impedance mode is 10 ohms output impedance, which is too much. http://www.tubehifi.com/amp/amp/mgheaddt.html

post #43 of 58
Thread Starter 
post #44 of 58
Quote:
Originally Posted by zackk View Post
 

This intrigues me...

 

http://www.mav-audio.com/base/product/d1p


That looks like it might just have a tube preamp out. 

The Aune T1 is a popular, low-cost tube DAC. Have you looked at that one?

post #45 of 58
Thread Starter 

The Aune seems like it would be pulled right off the rack with the heavy Grado chord. It also doesn't seem like the kind of value you'd get from larger amps like the Little Dot.

 

Does the Grant Fidelity TubeDac have the tube section only in preout, and not in the headphone amp circuit?

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