Any chance of a headphone out on the LLC-Purist?

taketwo · « **on:** 25 Jun 2003, 04:10 am »

Sometimes there is a need to listen to headphones so this would be a nice feature.

Curt · « **Reply #1 on:** 25 Jun 2003, 07:44 am »

What is the impedance of your headphones? How many ohms?

taketwo · « **Reply #2 on:** 25 Jun 2003, 10:06 am »

Quote from: Curt

What is the impedance of your headphones? How many ohms?

It varies. From 32ohm Grados to Senheisers HD600 at 300ohms and AKG501 at 120ohm. Primary headphones are the Senns and AKGs. Hardest to drive is the AKG501. It seems to need a lot of current.

So it's possible?

If you can do this you'll gain a hell lot of audience from the headphone crowd over at www.head-fi.org and www.headwize.com. The headphone out has to be very good though. Looking at the step attenuator and build of the LLC-Purist, it would provide very tough competition over those dedicated headphone amps mentioned in those forums. Some examples include the Gilmore V2 www.headamp.com and Corda PreHead www.meier-audio.com which can also act as a preamp. But I think yours is way better built and more flexible.

Curt · « **Reply #3 on:** 25 Jun 2003, 05:51 pm »

Thanks for your good input. We only had a few requests for headphone amps in the past, but I do wonder if we did add a good headphone amp, would more customers find their way to IRDs preamps.

We will tweak and change the IRD components, over time, to better fit the markets demand.

The Purist has separate output drivers for each set of outputs (it has 2 sets), and it may be possible to drive a low impedance (up to 120 ohm) efficient set of headphones directly off one set of outputs (RCAs). I have not tried it yet but I believe the output current is sufficient.

I doubt the Purist would work well with low efficiency hard to drive (250-300 ohm) headphones the way it is now. We could add a dedicated headamp to the PCB and an output jack at the rear panel (in the next Purist revision) if there was enough demand.

If you have headphone experience here are questions for you:

How important are special circuits, circuits that enhance headphone listening, like the crossfeed filter? Are they really an improvement?

Is a normal (no enhancement circuit), excellent sounding (maybe class A) amp enough to satisfy most headphone users?

nathanm · « **Reply #4 on:** 25 Jun 2003, 09:33 pm »

I think it would be quite handy to have a headphone jack on there. (I personally am awaiting the release of the LLC-A though, not the Purist)

Call it audiophile anathema if you wish, but for headphone use I would not mind having some tone controls!

Like if there was a headphone amp that could grant the HD600s its otherwise totally rolled off low end (IMHO) that would be nice. The crossfeed circuit would also be interesting. I have heard this effect using Headphone.com's small portable amp and it was nice to have the option.

My vote would have to go towards quantity and not just quality as far as options go. Cause even an 'excellent sounding Class A amp' is still only ONE type of great sound. With headphones the sound is mashed right into your head and so it would be cool to have a little bit of control over tonal balance. Brighter recordings can be quite painful and fatiguing otherwise.

taketwo · « **Reply #5 on:** 25 Jun 2003, 11:50 pm »

Quote from: Curt

How important are special circuits, circuits that enhance headphone listening, like the crossfeed filter? Are they really an improvement?

Is a normal (no enhancement circuit), excellent sounding (maybe class A) amp enough to satisfy most headphone users?

Not really but it's a nice option to have and can be a major selling point. Go to the Corda website www.meier-audio.com It explains crossfeed very well. But it's not an absolutely essential item. Some of the best headphone amps out there do not have crossfeed. Some which comes to mind include the Sugden Headmaster, ASL MGHead OTL, ASL TwinHead, AudioValve RKV, Berning Zotl, Melos SHA-1, etc. Some of these even started out as preamps which happen to have very good and well implemented headphone sections. I can think of only 2 which have crossfeed that are well implemented. Those from Headroom www.headphone.com and Corda www.meier-audio.com I think most prefer the crossfeed implementation from the Corda. It seems that a good crossfeed filter is not easy to implement.

I suggest you solicit the impressions of the crowd over in www.head-fi.org and www.headwize.com I'm sure they will be excited over the LLC-Purist should it have a very good headphone amp section. The build and price alone will make them go gaga.

Personally the crossfeed is just a bonus for me. I prefer if it can drive almost any headphones out there.

taketwo · « **Reply #6 on:** 25 Jun 2003, 11:59 pm »

Quote from: nathanm

Like if there was a headphone amp that could grant the HD600s its otherwise totally rolled off low end (IMHO) that would be nice.

The problem with the HD600 is that not many headphone amps can drive it to its full potential. That is one headphone which will scale with you as you upgrade. I've heard it accused of being veiled and distant sounding. But match it with something like the ASL Twinhead (USD$1895 ouch!) or Headroom Blockhead (USD$3888 ouch! ouch!) rolled off, veiled and distant sounding would be the last thing on your mind.

nathanm · « **Reply #7 on:** 26 Jun 2003, 03:09 am »

As a matter of fact I have matched it with an ASL Twinhead!

I had this preamp for a few weeks before returning it. It didn't work any real magic with the HD 600's lack of bottom. I also have an ASL MG Head which I like, but I still would describe the 600's bass as rolled off or perhaps "polite" is a nicer term. (the OTL jack has more grunt in the lower octaves) It's certainly NOT a "veiled" sounding headphone, though! It's extremely clear, perhaps at the expense of bass I suppose.

If Curt's pre had like a +6db bump at say 60Hz 1 octave bandwidth that might be nice. Just a thought... Maybe one of them "Loudness" switches I missed out on in the '70s???

eico1 · « **Reply #8 on:** 26 Jun 2003, 03:43 am »

just use a small power amp to drive your headphones, at least a stereo ird-100 or what-not:). You can't tack on a good implementation to a pre that isn't already using high voltage supplies.

steve

taketwo · « **Reply #9 on:** 26 Jun 2003, 04:06 am »

You know I'd never characterised the HD600 as having a lack of bottom. Roll off maybe with lesser amps. I had mine paired with the Sugden Headmaster and the bass was tight and deep.

So you had it paired with the ASL Twinhead? Oh wow. Was it the MKII? Not many has heard that combo. Care to share?

Oops might be OT.

nathanm · « **Reply #10 on:** 26 Jun 2003, 04:43 am »

Sorry, off-topic, but...HD comments

I have no idea what IRD's preamps sound like, but I would be willing to bet they are built far better and have much lower noise floor. The TwinHead was the noisiest piece of gear I've ever used. And the tubes were exceedingly microphonic to the point where every tap of the rack was amplified through the speakers. Not worth $1300 that's for sure.

taketwo · « **Reply #11 on:** 26 Jun 2003, 06:20 am »

At $1300 it sounds a lot like the old MKI. The MKII is $1895 if I recall correctly and supposedly sounds quite different.

Thanks for the impressions.

Thump553 · « **Reply #12 on:** 26 Jun 2003, 07:11 pm »

I listen to Senn 600s several hours a day and have been doing so for over a year. Never in my wildest imagination would I say they have rolled off bass.

Adding a headphone jack could be a good idea, but it should be in the front, not the back. And a quick review of the sites mentioned above (esp. head-fi.org and jan meier's) should quickly convince you that people who are serious about headphones almost always have their own (expensive) headphone amps. IRD making a seperate headphone amp could be very interesting. There are only a couple of high quality headphone amplifier manufacturers out there, especially if you exclude the basement workshop types (some of whom make very good amps).

Curt · « **Reply #13 on:** 17 Jul 2003, 06:56 pm »

Got busy there for a while sorry for the delay.

Yes, the headphone issue is pretty complex. Our preamps only have +/- 18VDC rails which 2V more than some of the specialized amps have but it seems boarderline to me for some HPs.

They come in several types and different impedances and they need to be treated differently. Yes, HPs require some special attention, to really do them justice, especially for serious audiophile users.

I think we will mull this over and possibly wait to produce a dedicated unit someday which at our low pricing may only run a few hundred dollars and be able to work well with all types of headphones.

I really don't like to do anything half way, to add a bad HP amp to our preamps would just be a waste and possibly even degrade the preamps performance as well.

taketwo · « **Reply #14 on:** 18 Jul 2003, 07:51 am »

Quote from: Curt

Got busy there for a while sorry for the delay.

Yes, the headphone issue is pretty complex. Our preamps only have +/- 18VDC rails which 2V more than some of the specialized amps have but it seems boarderline to me for some HPs.

They come in several types and different impedances and they need to be treated differently. Yes, HPs require some special attention, to really do them justice, especially for serious audiophile users.

I think we will mull this over and possibly wait to produce a dedicated u ...

Hey thanks Curt. If you can do one for only "a few hundred dollars", say below $400 ($300 would be great!) and it can do justice to all types of headphones, I'd say you'll have a winner in your hands.

SIDENOTE : If you want to get a feel of headphone amps and what your product will be competing with, the Singapore Headphone User Group over at www.sgheadphones.com will be holding a meet sometime in August - October timeframe. You'll get a chance to hear the Gilmore V2, Creek, Corda amps, Meta42s, MF X-Cans, Berning MicroZotl and many many others, not to mention the variety of headphones that will be used with them. It's only a 2.5 hours flight from Thailand you know.

Time for a holiday don't you think?

Curt · « **Reply #15 on:** 18 Jul 2003, 07:14 pm »

Taketwo,

A very interesting offer since it's not too far to travel. I will think about this, might be nice to see/ hear so much HP gear all in one place.

Thanks, I'll check out and bookmark the groups link.

Thump553 · « **Reply #16 on:** 18 Jul 2003, 07:56 pm »

Curt:

I think you are taking the right approach. But don't abandon the project-if you can come out with a high quality $500 headphone amp, there are a lot of buyers out there in that market. Two reccommendations: First, really research crossfeed and do the best, most adaptable implementation of it you can. My current amp (otherwise top quality) doesn't have it and I miss it-to the extent I will probably pick up an external unit someday.

Secondly, the Senn 600 is the 800 pound gorilla of the headphone market. It is probably the most popular high quality headphone by far. So even though it is hard to drive, do not ignore it. In fact, if you built your hypothetical headphone amp specifically to drive the HD600, you would have a very ready and large market.

Curt · « **Reply #17 on:** 23 Jul 2003, 02:32 pm »

Quote from: Thump553

Curt:

I think you are taking the right approach. But don't abandon the project-if you can come out with a high quality $500 headphone amp, there are a lot of buyers out there in that market. Two reccommendations: First, really research crossfeed and do the best, most adaptable implementation of it you can. My current amp (otherwise top quality) doesn't have it and I miss it-to the extent I will probably pick up an external unit someday.

Secondly, the Senn 600 is the 800 pound gorilla of the head ...

Thanks for the input. I'm familiar with most of the HP stuff already, just don't use them. Haven't used HPs for more than 20 years. But your right, there are quite a few people interested in using HPs.

I like the 600s and believe they are a very popular model, probably the most popular. I am familiar with crossfeed and several non-crossfeed type HP amplifiers. I'm familiar with many of the HP amp circuits and have many of my own ideas for a good HP amp.

This is an interesting area of audio, a place IRD has not ventured into yet. A well built, good sounding, reasonably priced amplifier may help more people get into a good HP system.

I will pick up a pair of 600s and try using them at night while I work. I normally work till about 4am, music would be nice. It would give me a chance to listen and see where HPs are today. This will be a good place to start.