Headphone amp?

funkmonkey · « **on:** 31 May 2009, 11:39 pm »

I have been thoroughly enjoying my LS-36.5 for around 9 months, and I am very happy with it's performance. But, I miss having a place to jack in a pair of headphones... Which brings up a couple of questions for Dan:

Is it possible to integrate a headphone amp into a one box LS-36.5 (via new mod)?
and/or could it serve as one using the main outs directly into a set of cans?
Have you considered building a stand alone headphone amp, to run along side of your one of your preamps?

Sometimes I am forced to listen through headphones so as to not disturb the neighbors or my sleeping wife (and as of now I cannot listen to my home system this way so I end up listening to my less than stellar portable rig). Considering the rather large investment that I have in my home system I would love to be able to enjoy my MW Transporter, and LS-36.5 through a set of cans when I have to keep it quiet.

Any thoughts along these lines and are there any others that might be interested in something like this?

I had a chance to hear some amazing gear yesterday (at a head-fi meet) including some excellent tubed "desktop" pre-amp/headphone amps that were similarly priced to the 36.5. As I don't really have much room to add another full sized piece to my rack a headphone out mod/addition would be ideal for me. If such a thing is not feasible, I may reluctantly have to move to something that offers both functions.

If nothing else, maybe this could serve as food for thought for future Modwright gear (believe me, there is a substantial market for high quality headphone amps). I thought this may be a logical next step, considering the success of Dan's full size KWA-150, perhaps a little brother (tubed?) could have a place in the line-up...

Cheers,
Greg

cAsE sEnSiTiVe · « **Reply #1 on:** 1 Jun 2009, 04:09 am »

Something along the lines of this?

The MWTP sounds marvelous through a nice headphone rig. The amps are custom-built b22 balanced. I am utilizing a Music Vault wirelessly to the transporter.

funkmonkey · « **Reply #2 on:** 1 Jun 2009, 06:37 pm »

Nice rig, cAsE sEnSiTiVe. That b22 looks pretty sweet. Do you use your TP through a speaker oriented system as well? Or just for the headphone rig? I'm curious how you have it hooked up if you are feeding both.

cAsE sEnSiTiVe · « **Reply #3 on:** 1 Jun 2009, 10:00 pm »

Funk,

The beauty of the b22 design is that it will drive an efficient pair of speakers as well as of course headphones. I recently sold a pair of Zu Definitions that I was driving quite nicely with the b22. Simply hooked up the speaker cables to the back of the amp, and that's all there is to it. Since the amp is a DIY, you can use any cases that appeal to your eye. You can build it single-ended, or balanced, or both, as mine is. It is a fantastic sounding amplifier. I was a die-hard tube guy before listening to it.

Here is a bit of info on it: http://www.amb.org/audio/beta22/

Take care,
Bob

ecramer · « **Reply #4 on:** 1 Jun 2009, 10:33 pm »

the b22's are some really nice amps

Quote from: cAsE sEnSiTiVe on 1 Jun 2009, 10:00 pm

Funk,

The beauty of the b22 design is that it will drive an efficient pair of speakers as well as of course headphones. I recently sold a pair of Zu Definitions that I was driving quite nicely with the b22. Simply hooked up the speaker cables to the back of the amp, and that's all there is to it. Since the amp is a DIY, you can use any cases that appeal to your eye. You can build it single-ended, or balanced, or both, as mine is. It is a fantastic sounding amplifier. I was a die-hard tube guy before listening to it.

Here is a bit of info on it: http://www.amb.org/audio/beta22/

Take care,
Bob

thalvor · « **Reply #5 on:** 2 Jun 2009, 09:16 am »

I am currently in the market for a new headphone amp. Any indiciation of a ModWright headphone amp in the not too distant future and I would gladly postpone my purchase.

modwright · « **Reply #6 on:** 2 Jun 2009, 09:06 pm »

First of all, thank you for bringing this up and expressing interest.

There are a couple of ways that we could go here. The output stage of the LS 36.5 is not conducive to directly driving 'cans', but we could add a simple SS circuit to allow for such impedance matching. There are also other ways of integrating this capability into an existing MWI preamp.

You bring up another interesting point, which is a good, compact headphone amp, to pair with our existing gear.

I have to admit that while I have a pair of Grados and listen to headphones from time to time, it is not a world that I am THAT familiar with. I do however know what is required to adapt any of our existing tube designs to drive headphones and it COULD be done.

I can't promise that we will have a product IMMEDIATELY, but this IS something that I have considered for some time and this thread is the nudge that I needed to take the next step.

Please check back at this thread and I will share my progress and ideas.

If we were to do this, which would be of greater interes?

1) A standalone tube headphone amp?
2) A quality headphone out circuit that could be added to our preamps?

I suppose the real answer is both, as there are customers who don't have MWI preamps that would be interested and vice-versa.

In terms of a headphone amp, what features are of interest? I know that many people enjoy having balanced outputs. I am honestly not that familiar with other wishes that avid headphone listeners might have.

Thanks!

Dan W.

Tyson · « **Reply #7 on:** 2 Jun 2009, 11:59 pm »

I'm a big headphone listener and I think the question is whether the amp is aspiring to be a "great" amp, or merely good. If the former, then I think that it should have a massive power supply, be switchable between single ended input and balanced input, as well as switchable between balanced output and single ended output. If it's a tube amp, it should be switchable between OTL output (for high impedance headphones), and a transformer coupled output (for low impedance headphones). Finally, it should be able to swap a good variety of tubes, in order to get the sound just right for different people's tastes.

funkmonkey · « **Reply #8 on:** 3 Jun 2009, 12:21 am »

Thanks for your reply, Dan. Personally, I would much rather listen through my speakers, but as stated above (out of courtesy to my wife and neighbors), I also listen through headphones during late night sessions. It is not a world that I am all that familiar with either. Guys like Tyson would be much more helpful for developing a standalone (I get the feeling that he just described the ideal headphone amp

). That being said, and considering additional rack space, option 2 [added headphone circuit] would be my first choice. However, if you were to develop a really trick tubed and balance standalone (that wasn't too expensive) I just might be able to find some space for it.

In all honesty adding a headphone out circuit would satisfy me, but building a standalone would introduce a whole new set of potential clients (and potential Modwright fanatics).

Cheers,
Greg

modwright · « **Reply #9 on:** 6 Jun 2009, 08:25 pm »

Thanks guys. We may consider offering a headphone output for our future preamp designs. It would not be that difficult and would certainly add value to our product.

RE a dedicated headphone amp, if we do it, it WILL be great, not just good. I have no interest offering any product that is merely GOOD.

We could do both SS and tube designs. If tubed, I agree that it should be able to use a number of different tubes. We have some circuits already that could be adapted to such a design that have EXCEPTIONAL performance.

Thank you all for your feedback as it is ALL considered!

Sincerely,

Dan W.

shirtaspants · « **Reply #10 on:** 6 Jun 2009, 09:03 pm »

I'm for anything where it helps integrate headphones and speakers into one set of backend electronics.

That said, headphone amp trends have shifted from souped-up preamps to specialized power amps IMO. The B22 cited earlier in the thread is a great example. Incidentally, I would love to see a Modwright effort in the <= 30 wpc area for speakers. Perhaps a high quality, low power integrated with a headphone out tapped from the speaker output? Tube or SS, hybrid might be an interesting option.

Thank you for taking the headphone realm seriously.

Tyson · « **Reply #11 on:** 6 Jun 2009, 10:58 pm »

I would say that the ability to switch between transformer coupled and OTL outputs is one of the most important features, and one of the least commonly available. Sennheiser headphones such as the HD600 or 650 have 600z impedance, while Grado's and Denon's have under 40z. OTL's will be a good match for Senn's, but a only a transformer coupled amp will handle the Grados or Denons properly.

shirtaspants · « **Reply #12 on:** 7 Jun 2009, 12:55 am »

There's nothing that prevents transformer coupled outputs from driving Senns well. I do agree that being able to drive a range of impedances optimally is valuable, and then let's just let the topology sort itself out after that.

Tyson · « **Reply #13 on:** 7 Jun 2009, 01:01 am »

Actually, not true. The Senn's have a reputation for having a "veil", but that is only because most people drive them with amps that have too low of an impedance. OTL's match up VERY well with high impedance headphones, and in the case of the Senn's, it lifts that veil and makes them sound incredible. On the other hand, OTL's with Grado's or Denon's lead to soggy bass and a very compressed type of sound.

modwright · « **Reply #14 on:** 7 Jun 2009, 01:22 am »

Wow, thanks guys! Good info and much appreciated!

I had always considered using our preamp circuits to drive headphones, as they are high-current designs to begin with.

I had not considered the notion of a < 50W integrated that was also a great headphone amp. I am thinking that a 30W or so, pure Class A or close to it, design, could be quite interesting in this regard.

I also really appreciate the info about the Sennheisers and OTL amps. I will have to do some further research into this.

Please keep the thoughts and ideas coming, especially options and desired combinations, especially if they are not currently available and desired!

Take care,

Dan W.

shirtaspants · « **Reply #15 on:** 7 Jun 2009, 02:13 am »

Quote from: Tyson on 7 Jun 2009, 01:01 am

Actually, not true. The Senn's have a reputation for having a "veil", but that is only because most people drive them with amps that have too low of an impedance. OTL's match up VERY well with high impedance headphones, and in the case of the Senn's, it lifts that veil and makes them sound incredible. On the other hand, OTL's with Grado's or Denon's lead to soggy bass and a very compressed type of sound.

The Eddie Current Nautilus (I bought the prototype and have run it w/ 650s), along with the Balancing Act and TTVJ 307A, just to begin with, beg to disagree with you

What about all the SS amps that do well with them too? B22, Luxman, etc. As far as I understand correctly, typical SS output impedances make trafo-coupled tubes look like high Z.

Also, the Zana Deux, an OTL that reportedly is heaven with Senns, has an output impedance of only 12.5 ohms.

Point is, yes, OTLs do match up well with high impedance loads. But, looking at just the output Z and making proclamations from there is a bit shortsighted.

Tyson · « **Reply #16 on:** 7 Jun 2009, 02:50 am »

Well, a good amp is a good amp. But, it makes more sense to impedance match amps to headphones/speakers/drivers as closely as possible. That's why having BOTH options in a single amp (high impedance and low impedance) makes far more sense than having to choose one or the other.

gregeas · « **Reply #17 on:** 7 Jun 2009, 02:07 pm »

I too would love to see a MW headphone amp (or, even better, a line of amps). Now that Singlepower has flamed out -- see the epic thread at Head-fi.org -- it looks like there will be an opening in the market for a reputable builder of high-amp head amps.

I'll offer a few suggestions:

* Check out the new Sennheiser HD800s. I'm burning in a pair right now, and they are the closest thing I've heard to speakers -- the imaging is incredible. I suspect Senn will sell a large number of these headphones, so voicing a great amp for them could be a good call.

* I'd like to see the solid-state amp come in a half-rack-width case like the Benchmark DAC1. This way it could be transported for high-end use when traveling, etc. I love how the DAC1 fits in my laptop bag, but the integrated headphone amp leaves something to be desired. A compact *balanced* amp could be amazing. The Singlepower Squarewave is the only example of this I can think of.

* I like the idea of a bigger tube headphone amp also serving as a pre-amp... I personally don't have the space in my rack for a full-sized pre-amp and a fulll-sized headamp. Along those lines, would it be possible to integrate the headphone circuit in the Transporter?

modwright · « **Reply #18 on:** 7 Jun 2009, 09:08 pm »

Thanks again for all of this information. Adding a headphone amp to our preamps would not be difficult. I expect that the same could be done with the Transporter also, but please don't take this as a commitment that we are ready to do so. I first need to investigate whether transformer coupling or SS OP buffering is the best way to achieve the appropriate Low Z needed for just about ANY headphones, to be fed from our existing preamp or Transporter designs.

The LS 36.5 and Transporter have Zout of approx. 100ohm, but that is still not low enough to effectively drive headphones. I need to investigate the OTL option also. This would likely be a pretty specific design for headphones with a different tube complement. One of the problems that I see with OTL designs is that you still need to cap-couple the outputs and to do so without losing bass, means LARGE value coupling caps = electrolytics. Now perhaps if this electrolytic cap is designed with the appropriate size quality film cap bypasses, to allow all but the lowest frequencies to pass through the electrolytic cap, then this might be a good way to go.

I am taking all of this in and am very interested in the prospect of either offering headphone outs on our preamps and/or designing dedicated headphone amps. We could do a SS design that would be compact. A tube design would not be compact or convenient for travelling.

Thanks,

Dan

Srajan Ebaen · « **Reply #19 on:** 11 Jun 2009, 06:34 am »

Here's a feature set I think would be cool:

A headphone/preamp with - 3 gain settings; 2 or 3 impedance taps to accommodate wide range of cans; 2 or 3 switchable inputs; 2 variable outputs (one to act as preamp, one for subwoofer), a front-mounted switch to change from headphone to preamp mode; a tube family that allows extensive rolling. With the number of ultra-efficient ear-canal phones available, super low noise is essential while more traditional statement phones from the likes of Grado, Sennheiser, AKG, Beyer, Denon etc. often thrive on superior drive.

In other words, this would be a dedicated headphone amp that could double nicely as a quality but minimalist preamp.

At the Munich show, a German importer told me the only areas seeing good growth are USB DACs and headphone-related items. Kinda makes sense. If true, a killer add-on feature for a ModWright headphone amp as proposed would be a good USB DAC. Now you'd have a superb PC-ready system. Hey, even reviewers are allowed to dream