[modwright]

OK guys, you know that we are working on a standalone DAC and phono.  These products are well under way and details being finalized.

Apparently having TOO much time on my hands.....(RIGHT!)   I am thinking about a headphone amp design.

Questions:

1) What headphones are most of you using?
2) Impedances?
3) Power requirements?
4) How do you use it?  Work? Desk? Listening room?
5) Tube design is my preference, but hybrid is also a possibility: Preferences?
6) Price points? High Quality tube or tube/hybrid design for BEST sound!

Looking at initially a headphone amp, followed by a combination headphone amp WITH DAC.
Possibly HP amp will offer DAC upgrade option.

Any/all input is welcome!

Thanks,

Dan W.

[roscoeiii]

Love my HiFiMan HE-5LE headphones. And I think that a decision you will need to make will be whether to have an amp that has the grunt required to drive some of these harder-to-drive headphones like the HE-5LEs or the HE-6s. A number of folks are pairing these phones with speaker amps using adapters. And most headfi type reviews (6moons too) tend to mention how well a headphone amp handles a tough-to-drive headphone. 

[milford3]

My best sounding headphones are 600 Ohm's.  Design an amp that has power, power, and more power.  All headphone amps have a gain knob. Just use it.

[Alleye]

I really wish Dan would stop coming up with great ideas for things I'm going to "need" to have! 

1) What headphones are most of you using?
Right now a pair of Westone UM2 IEM
(But I keep looking for a pair of Audeze LCD2 or LCD3s)

2) Impedances?
Westone - 27 ohms
Audeze  45 Ohms (purely resistive)

3) Power requirements?
Westone UM2 - Not much at 119db/mW - (So having a selectable gain for IEM and larger cans would be great)
Audeze LCD3 91db/mW (Recommended 1-4 watts)

4) How do you use it?  Work? Desk? Listening room?
Right now I'm using a RSA-Hornet daily at my desk/work. I use a line out DOC from a classic ipod, or my iphone if I'm streaming podcasts.
(While this might not fit with what you had in mind, something more or less portable would be awesome.)

5) Tube design is my preference, but hybrid is also a possibility: Preferences?
Either/or - If we can get the "trademark" ModWight sound  in something a little more portable - I'd tell you to just take my money now. 

6) Price points? High Quality tube or tube/hybrid design for BEST sound!
If I had to replace my Hornet today it looks like I'd be spending between $500-$700. Granted I was waiting to hear about Schiit Audio's Vali (less portable) which is going to be a hybrid and is suppose to run under $150. Overall, I'm looking for something with high quality sound, and I usually run to a "warmer" sound. So while that might be tube in description, I have always enjoyed my 100se and ls100 combo which I guess could be considered a hybrid design. 

Dan - Thanks again for thinking of us and if you need any other detail or have any specific questions feel free to drop me a line!

Thanks!

[terrycym]

I use Stax 507 headphones

[minimus]

I use JH Audio JH16s, which are custom IEMs.  Impedance is 18 Ohms, very easy to drive but pick up noise if there is any in the circuit.  I also use LCD-2s, which are 45 Ohms and fairly power hungry.

I only like desktop/home amps. All-tube design is preferred. Price point -- up to $2500 would be of interest.

[modwright]

I have looked at tube designs and they may work.  To be fully flexible with all headphones, will require transformer coupling.  This adds cost of course.

The other approach is a tube hybrid design, with the tube used as the voltage amplifier.  This approach interests me greatly.  We could use technology from our existing SS amps and tube designs.

I will be honest and say that it will NOT be < $1K for sure.  We are not going to compete with the portable or the Asian mf'd. market.

I am thinking of a desktop unit, not necessarily full rack width.  Ideally smaller for more flexible applications, such as office, desktop, etc.

I would prefer a design that can handle MOST if not all headphones out there.  A hybrid design would certainly make this more likely.

Thank you for your feedback so far and please continue to contribute, all who read this.

Sincerely,

Dan W.

[terrycym]

The Audeze are available with balanced XLR connectors.
Dan, will it have balanced output? 4 pin? 3 pin (two off)?

[dminches]

Dan, once you get into the >1000 price point (which is a good one!) you start to compete the with units made by Woo Audio and others.

The headphone categories include the low impedance planers (Audez'e, HiFiman, ATH) and higher impedance cans (Beyer, Sennheiser).  The HiFiman HE-6 are the most difficult to drive, followed by the Audez'e.

The tube amps are very popular since people like to be able to tune the sound to their headphone and liking.

[FullRangeMan]

The Audeze are available with balanced XLR connectors.
Dan, will it have balanced output? 4 pin? 3 pin (two off)?

What XLR connector should I use single 4 pins or dual 3 pins??
Seems in the dual 3 pins the third pin(ground) is unused??
I assume the sound quality are the same in both types.
Please advice.

[johzel]

Would anyone like to see a remote volume control other than myself?  Yup . . . 10 feet is a long way to walk 

[HPDJ]

Hey all,

Cool to see a manufacturer like Modwright looking to get into the head-fi game! I have headphones right now (and desktop speakers...no loudspeakers yet) and I feel like high-end audio manufacturers who are starting to get into headphone gear are creating a bridge for adopters of their headphone-related gear to eventually have the option/gain the interest in looking at their even higher-end gear outside of the headphone world (ie the speaker world)....and since headphones involve a large amount of young listeners, it brings with it the potential to draw in younger audio enthusiasts and get them "on your team" early on. Does this make sense?? If I liked what your gear made my music sound like with the headphone component you created, I'd feel more comfortable exploring your options for speaker related gear. You would have built-up my trust as a consumer in this scenario and thus increased your chances of having a long-term customer 

Anyway, I thought I'd offer something to this thread:

-I have Audeze LCD 2 headphones. That's it. I'm a one headphone kind of guy myself

-I have a Red Wine Audio Signature 16 Speaker/headphone amp (I LOVE it). Now, one of my favorite things about this amp is that it's a hybrid design. I feel like (with my amp in particular anyway) I don't have to worry about getting super expensive/rare tubes to make it sound it's best. That kind of stuff would keep me up at night (I know, it's sad but kinda true). This is a BIG turn-off for me! The simpler the better (for me) and if you can create an amp that's not SO tube-type (*expensive*) reliant then I think that is a huge plus. Some will disagree obviously. But having the option to roll tubes and change the flavor is sweet....again, as long as that's not a requirement to make it sound it's best.......which is subjective anyway so, yeah I know it's a tricky thing.

-Head-fi folks seem very interested in a product with some amount of flexibility so gain adjustability would be cool (as someone has mentioned already). New headphone amps seem to get minus points when they are in their lower-gain stages and they still emit some amount of noise when in use with IEM's. An amp that is powerful enough to use with the most power-hungry of headphones like the HE6's/K1000's, BUT can also be DEAD quite with IEM's would be a rare feat.

-I think a remote control is a PLUS, but not a necessity.

-If it's gonna use tubes, the easier the tubes are to access for tube rolling, the better..

-Some folks want XLR inputs....don't matter much to me but if you can include XLR and RCA inputs it could be a bonus for some.

-Balanced balanced balanced. Folks want balanced headphone outputs. The 4 pin type is a bit more standard now. Include a 1/4 inch headphone out, WITH a balanced 4 pin one and that would be super I think!

-For me, I wanted my headphone amp to also be a speaker amp so I could power my desktop speakers...I don't have space for both types. IF you were to consider such an option, then including a switch to mute the speakers when using headphones is a must in my book!

-Being able to easily follow what position the volume knob is at is BIG for me because when I switch from speakers to headphones on my amp, the volume will either be too loud or too quiet and I'd like to glance at the volume knob and keep track of where it's at....hope that makes sense.

-Sure, a optional DAC would be awesome....lot's of folks want an amp/dac together these days.

-An amp that is modular in the sense that it's upgradeable (future proof) is ideal. Even the DAC section, if you go that route. Options are nice!

-2 inputs are minimum in my book. 3 is really great.   

-Desktop appropriate size is great. Some big hulking piece of metal is reassuring to audiophiles in many ways. It give the impression of something being carved out of stone and long-lasting. But for headphone gear....getting the size down is better. But not too small! Then I automatically assume it won't be able to hold it's own sonically against similarly priced gear.

Hope some of this helps stir the pot

[modwright]

Wow! Great feedback!

I AM interested in the headphone amp market as a gateway to reaching younger customers!  It is a blossoming market, as is vinyl of course.

XLR inputs is not a problem.  I will see if they should be 3-pin or 4-pin as we get closer in.

I also agree that it would be a good option if it can power speakers, such as desktop speakers and of course have multiple inputs.

Not sure about R/C, given that you ARE tethered to the amp via your headphones .

As far as tubes go, it WOULD be a standard, current-production type, that is readily available and has a lot of tube rolling options.  I have been working with the 6922 family lately and I like that tube for lots of reasons.

Hybrid design makes a lot of sense in terms of power hungry designs.  I will explore both of course, but this DOES look appealing.

Again, thank you SO MUCH for this input!  This IS a product for our customers, so knowing what our CUSTOMERS want is KEY to the design!

Take care and please keep the info coming!

Dan Wright
President,
ModWright Instruments Inc.

[DaveBSC]

A Modwright HPA? Yes please! Making an amp that is well suited for both IEMs and Orthodynamics is very challenging. If you have to pick one at the expense of the other, I would suggest leaning towards Orthos - that means at least a good 3W of power, and loads of current for ~32Ohm designs. If the amp can deliver that, the 300-600 Ohm stuff shouldn't have any problems. Of course a gain switch will help.

Output impedance must be less than 1 Ohm, and the more V she can swing PP (while keeping noise at bay), the better. I would suggest at least one pair of RCA and XLR inputs, a 4-bin balanced and 1/4" SE headphone out, and preferably a pair of RCA and XLR outs so it can double as a preamp. Speaker outs are up to you, but I wouldn't compromise on the HPA to get more power for the speaker outs. More people are likely to use it as a preamp paired with actives on the desk than a speaker amp paired with passives.

Volume control should be first rate. Please no $20 Alps Blue Velvet pots or noisy DACT steppers. I know the RK50 wont be possible at the price you are after, but you could probably put the Acoustic Dimension 41-step SA in there without blowing your budget.

[HPDJ]

Yeah for me powering desktop speakers was a MUST because this sector of the speaker world is growing SUPER fast as well and there are some really great speaker options right now that have been created with the desktop in mind primarily. I can't say that I've heard many of them, but it might be fun for you to hear them at some point (if you haven't already). And a lot of the folks who would be looking into those kinds of speakers are (I think) folks who have/want hi-end headphones. It's all becoming part of the same universe in a way that I don't think it's quite been before. All of the great options that computer audio has to offer, are right in that universe as well. Space-limited folks like me are just loving this realm of the audio world

I feel like I have a really super desktop system, and my sights are on high-end speakers at some point (sooner rather than later hopefully). I read a lot about speakers now (loudspeakers and bookshelf's) and bookmark the ones that seem interesting to me.

*I find that I'm barely feeling the need to read about amps and dacs as much because I'm happy with what I have and they are both upgradeable should I want to take advantage*.

Then, when the time is right, I will audition the speakers that still have managed to interest me and bring along my little amp to find the right match for it. Or I'll do auditions with companies that have good in-home trial periods. The speakers will have to be on the more efficient side, but....there's lot's of great options out there for these kinds of speakers now as well! In a way this helps narrow down my choices!

So I've really tried to get most of my "pieces" in line now so that my biggest concern in the future will mostly be just finding the right speaker....not finding the right DAC and Amp and cables etc etc. I want things to be easy so I can just focus on the music. The vinyl side of my rig will need a bit more work I think (though it's quite good now), but the digital side will for the most part be covered for a long while. That put's me at ease...

Oh and that's why the remote is a nice option for me, because when my amazing new speakers arrive in the future (whatever they end up being) and my amp is no longer within my reach....that remote will become even more useful. I appreciate it's function now though (I barely touch the volume knob anymore...only to fine-tune the volume level)....but I wouldn't cry if it didn't come with my amp right now. Maybe it's something you can make optional for an added fee? I don't know haha

Anyway, all the best with your headphone amp exploration!

[modwright]

Hi guys and thanks.

The design would be meant for 'Ortho's', but should be able to accommodate IEM's also.  Obviously a BIG difference in power/sensitivity there.  Perhaps the mini stereo plug would ONLY be connected to the lower power output, while the standard jack would be connected to the higher power output.  Of course a hi/low gain switch would not be a problem.

I will have to research the VC options.  I agree that for a high-end product, it would need to be a HIGH QUALITY attenuator.  TVC's are my fave, but they ARE expensive!

Alps RK50  - yeah right!  Wow!  Those are CRAZY expensive!

I will see what we can do with regard to power and connections for speakers.  Flexibility IS key with this design obviously.

Thanks!

Dan

[dminches]

Dan, does an amp that drives both speakers and headphones compromise the headphone impedance matching of the transformer since you need to limit it to 8 and 16 phms?

[Srajan Ebaen]

Hello Dan: A lot of this has already been covered so consider it mere confirmation 
IEMs up to 110dB down to about 85dB planars, impedance from 30 ohms to 600 ohms. For ultra-low output impedance and the lowest possible noise (vital for those IEMs) a hybrid would seem ideal. As you know circuit gain and output power work together on raw drive. The HifiMan HE-6 are said to like up to 4 watts into their 50-ohm load. I think that's a bit on the high side as I've had a number of far lower-powered amps that did well on the HE-6. It also depends on whether someone comes in with a weak-ass portable source or a 4V-out super DAC. I'd say you do want 2 watts into 50 ohms to cover all eventualities and if you can produce more without any noise, even better. A really good attenuator obviously is key. If the piece is to double as a preamp, remote control is nice and then a numerical display is always lovely to have. On connectivity, a 6.3mm plug, a 4-pin XLR and 2 x 3-pin XLR plus a 3.5mm plug would cover all apps. In desktop speaker scenarios a lot of headfi/DAC/pre pieces forget that small desktop speakers are routinely mated to a sub below the desk because the mains are small and bass shy - hence the need for a second pre-out.  On the desktop real estate is limited so any such piece that can double as a computer monitor stand (flat top that doesn't get too hot and doesn't mind being covered i.e. no heat exchange there) adds appeal. On the same subject, width is easier accommodated than depth. Plenty of computer monitors are 27" or bigger these days. But not everybody has 20 inches of depth they can accommodate before the piece hits their keyboard. So I'd recommend wider than deep and no taller than 6 inches feet included to serve that monitor-stand purpose.

If that sounds reasonable and appealing, why not have the tubes military-style but sticking out the front so you can see 'em and get to them easily? There are a number of designs to market that have very attractive variations on this subject to look fantastic.

Your idea of lower gain wired to the 3.5mm mini plugs sounds very reasonable. Another would be to have multiple gain selections, perhaps a three-tier voltage divider in front of the volume pot. That way it'd also affect the main out if someone wanted to use this with the built-in DAC option but run it in fixed-out mode. Now they could have the main volume control wide open but use the gain switch to set output voltage to 1V, 2V and 4V (or whatever happens to be a reasonable equivalent). Many modern DACs have far too much gain for amp/speaker systems to make it useful to preset their gain with a simple resistor in the signal path.

On the desktop, the more lights the more irritating I think. If you're thinking back lighting a nice option would be 'stealth' mode where you don't see any lights at all. If the tubes are visible, that's all the confirmation you need to know the thing is on...

[modwright]

Thank you Srajan, a lot of additional ideas that I had not considered.  I greatly appreciate it!

First I need to decide on the design.  Hybrid makes the most sense overall.

Next the VC choice (attenuator).

I will then entertain what options are needed and physical space requirements are.

Agreed on connectivity and your idea for varying gains is right along the lines of what I was thinking of.

If a hybrid, there WILL likely be a transformer involved, but not necessarily in the way that many would expect.

I really appreciate this!

Dan

[DaveBSC]

I will have to research the VC options.  I agree that for a high-end product, it would need to be a HIGH QUALITY attenuator.  TVC's are my fave, but they ARE expensive!

Alps RK50  - yeah right!  Wow!  Those are CRAZY expensive!

Dan

Yep, plus headphones have a way of acting as microscopes in terms of exposing bad designs and bad components. The typical cheap conductive plastic pot need not apply. I used a Khozmo 48-stepper on a custom made KGSSHV Stax amp. Great sounding SA with very precise 1dB steps from 12-48, BUT they are massively unreliable, and I wouldn't recommend them for a commercial product.

The Acoustic Dimension has 1.5dB steps, which isn't quite as nice but it's still a world of difference over the 2dB steps on the usual 24-step DACTs and Goldpoints. Those are just too coarse for headphones. AD also sells a motorized version if you want to have remote VC.

http://www.acoustic-dimension.com/attenuators/attenuators-main.htm