[slindeman]

If by change frequency response, you mean impose a sort of static EQ curve to the sound, then you are right, Jan's crossfeed does not do this. It does, of course, dynamically affect the loudness of the frequencies in each channel as do all crossfeed circuits. I mean say you have a violin playing in the right channel only, with silence in the left channel. When you engage the crossfeed you hear the violin in the left channel. If that isn't a different frequency response, I don't know what is.

But I think what you are getting at is a different way of affecting frequency response where you get a static EQ effect. And you are right that Jan's crossfeed does not do this unless you include the pyschoacoustic affects.

 

[JML]

MRael, I have a Corda HA-1 coming from Jan Meier soon. I'll let you know what I hear with the ATH-W100.

This place has had a very bad influence on me in only a few months. Two new cans, new amp, new cables, new PDCP, new cassette portable... [sigh]

 

[Spad]

I'm beginning to think you fall in love too easily as the old song says. It seems that whatever you have in hand at the moment suddenly becomes the best of all possibilities. I'm sure you don't believe this, but one could easily come to that conclusion.

Back on point: Obviously the Corda's crossfeed isn't based on simple delays as you stated, and one of it's strengths is that it operates across the entire spectrum with little alteration. The amount of crossfeed varies dynamically so that instruments in the center of the sound stage aren't affected while crossfeed is effectively increased toward the fringes. So it's also not just some global EQ scheme.

I also believe the selectable crossfeed is an important feature of the Corda. It is especially effective at eliminating that "center of the orchestra" feeling common to many classical recordings. As one with decades of experience in listening to live symphonic performances, I say, without reservation, that the Corda provides the most realistic classical soundstage I've encountered over a variety of headphones.

Obviously I value your opinion, Mark. But to decide out-of-hand that the Corda is inferior without having even a modicum of the facts gives me pause. HeadRoom's system may be superior. Personally, I couldn't say. But I do know that the crossfeed design employed in the Corda should not be dismissed as being based simply on delay. You seem--and again, I know this isn't your intention--to equate crossfeed, at least in the case of the Corda, with an early-70s reverb unit.

 

[Spad]

Quote:

Originally posted by M Rael I can now clarify a little: When you listen to floor speakers, your right ear does not hear the crossfeed from the left speaker in a uniform way all up through the frequency range. Low frequencies are hardly attenuated at all, and the right ear will hear the left channel low frequencies at nearly full strength. In contrast, certain high frequencies are effectively 'shadowed' by the head itself, and these are more attenuated for that reason.

I'm sure you realize that the ear can't localize frequencies below about 160Hz, so there's little point in the designer addressing them. This is the reason small satellite systems can be so effective. With a crossover in this range, the bass module can be directly behind you and its output will still appear to come from the often diminutive front speakers.

During the mid-'80s Polk produced some amazing (and amazingly expensive for the time) speakers using what they called a "Stereo Dimensional Array." The speakers were connected by a cable which fed the entire left channel above a certain cutoff to the right channel and vice versa. The SDA unit then fed this, 180 degrees out of phase, to an identical set of drivers in the respective speakers. Obviously, this had the effect of cancelling the crosstalk between the speakers. Of course, it was a little more involved than this, but this is the gist of it. One would think such a system would sound awful.

The drawbacks were that set-up was crucial and there was a seriously restricted "sweet spot." Outside that, and they sounded like very good but ordinary speakers. Inside the sweet spot, however, they could (and usually did) sound spectacular. All those added drivers and electronics added significantly to price which was, as I recall, $2800. I bought a demo pair for $2200.

Julian Hirsch, if you're old enough to remember him, put together a $33,000 no-holds-barred system at the time. These were the speakers he chose.

Quote:

The HeadRoom process does not use a tone control (!), but because of the floorspeaker interactions and simulations the process is trying to mimic, the result involves a (subjectively perceived) warming of central stereo images, amoung other things. Its perfectly natural, inasmuch as trying to make headphones mimic loudspeakers is natural.

 

[Spad]

Quote:

Originally posted by M Rael I just got off the phone with HeadRoom and talked to Danny, their engineer and designer. It so happened he had a Meier amp and crossfeed circuit right there to discuss with me. I'm happy to be able to say with PROOF that the Meier design is equally complex to the HeadRoom, though different in the way it goes about 'solving' the required equations. Apparently there are certain unknowns involved, and one design might favor a different approach than the other, with neither one being superior in every single way. Danny was very candid about the Meier, and I appreciate that very much. So he knows exactly what the Meier crossfeed does and how it was designed and he's listened to it at length. Whats his conclusion? Now Spad, I'm surprised at you. You should know that a mild mannered and sedate personality like myself would never post such a possibly inflammatory answer off the top of my head like that. I'm going back to my tofu and prayer beads and pretend this thread never happened. This crossfeed controversy has thrown my chakra's all out of whack.

Well, Mark ol' pal, maybe you should read some of the stuff readily available on Head-Fi before reaching conclusions. That's sorta what this place is for, ya know. You could start here:



Ram, ram, babba ram

 

[jude]

Quote:

Originally posted by M Rael If it were up to me there would be factual information about crossfeed already located in set location on this website. Head-Fi is so totally geared toward opinion, with such little emphasis on educating, that I find myself falling into little mental potholes all the time. Its very frustrating. Within 10 days I could have interviews posted of both Jan Meier and a HeadRoom spokesman about crossfeed and the future of headphone related DSP. But why should I bother? Just to have it buried amid all the mass of regular opinion and point of view posts.

HeadWize has a nice big library if you're looking to do research outside of the forum format. I see no reason to attempt to duplicate HeadWize's library here unless Chu ever decides to take HeadWize down.

The centerpiece of Head-Fi is obviously its forum. And, yes, as with many forums, opinions are a big part of what we do here, eh? But I disagree with you about the "little emphasis on educating" bit. I think most members here are happy to educate when they can, as well as to offer opinions.

If you're looking for more on Meier's crossfeed, go to Meier Audio's web site, and this page specifically may help you.

 

[MacDEF]

Quote:

Originally posted by Spad A unique feature of the crossfeed circuitry of the CORDA HEADAMP is that it "recognizes" the virtual positions of the instruments and singers in a recording. The sound of an instrument in the middle of the soundstage will be equally present in both audio-channels and isn't given any crossfeed. A crossfeed signal is only generated for instruments that are not placed at the center. The more off-center the instrument is placed, the stronger the crossfeed and the longer its delay. This feature is called "natural crossfeed".

Remember, that's marketing talk -- it's not really describing anything different than HeadRoom's crossfeed

 

[KurtW]

This is the first time I've read this thread, which seems to be about crossfeed. I have both HeadRoom and Meier amps and have listened to their crossfeeds extensively, as well as measured them and read the facts about them.

Here is some good info on HeadRoom's processor: http://headwize.com/tech/headrm1_tech.htm

Here is some good info on the crossfeed used by Jan Meier in the Corda: http://headwize.com/projects/meier_prj.htm

Both use a delay of similar amounts to the lower freqencies, and less delay at higher frequencies. Because of the way Jan implemented the crossfeed in his circuit, he was able to eliminate the comb filter effect that is occurs in the HeadRoom circuit that causes a mono signal to not have a flat frequency response. The actual deviation from flat is not great (I've measured it but don't have the data here right now); I would say it's probably flatter than most headphones. The HeadRoom circuit requires the use of treble boost (they call it a filter) for flatest response, where the Corda circuit is measures flat with a mono signal. It will not be flat, however, when the crossfeed is switched on if you just feed in one channel.

Without the filter, the HeadRoom "processor" definitely dulls the highs. With the filter (which is not on the Airheads) it sounds pretty flat, but does have a slight bass boost. I believe thev have reduced the amount of the boost somewhat in the new designs, which is a good thing IMO. On some material there sounds like a slight loss of bass with the crossfeed on with the Corda, and the HeadRoom compensates (sometimes over compensates) for this.

The effect of the HeadRoom processor or Meier crossfeed (same thing, different name) sounds slightly different but in my opinion both do what they set out to do, and about equally well. I personally prefer the Jan Meier circuit overall only because it upsets the overall frequency balance of the music less than the HeadRoom circuit. On the Corda there is three levels of crossfeed to choose from, on the Porta Corda there is just one but it's adjustable by changing out one resistor. I find myself using the the lowest setting most of the time, but use the med. or highest setting on some material with extreme seperation.

 

[M Rael]

Great post KurtW, thank you.
And if you're reading this and its the year 2003, then it means you're doing a search on crossfeed and you finally found us. Hi there! And it also means Jude never did implement any kind of data base.

My problem was that I didnt go to Headwize. My bad.

 

[Spad]

Quote:

Originally posted by MacDEF Remember, that's marketing talk -- it's not really describing anything different than HeadRoom's crossfeed

Of course it's marketing hype, but it's nonetheless true. And I believe you'll agree that Kurt isn't trying to hype a thing.

I believe if Jan had simply brought the Corda to market without releasing his design information, he could have doubled the price and we would be singing the praises of the "wonder" amp.

I can see it now:

Man, it measures almost flat from DC to 300khz!

Wow, pure class A operation in many cases!

Selectable crossfeed!

It's super adaptable with two headphone inputs of 0 and 120 ohms!

Wow, no wall wart!

A regulated power supply!

It's so well buffered that it runs for several seconds after the power is removed!

It's totally silent, even at max volume!

The construction is as solid as anything on the market!

At $650 it's a third less the the MOH!

Pssst. I know where you can get it for half that.

 

[Spad]

Quote:

Originally posted by jude HeadWize has a nice big library if you're looking to do research outside of the forum format. I see no reason to attempt to duplicate HeadWize's library here unless Chu ever decides to take HeadWize down. The centerpiece of Head-Fi is obviously its forum. And, yes, as with many forums, opinions are a big part of what we do here, eh? But I disagree with you about the "little emphasis on educating" bit. I think most members here are happy to educate when they can, as well as to offer opinions. If you're looking for more on Meier's crossfeed, go to Meier Audio's web site, and this page specifically may help you.

I think we just have to be mindful that the HeadWize library exists. I believe Head-Fi and HeadWize are very complementary sites and I rely on them both. When making my own first head amp decision, HeadWize's library played a decisive role in reaching my decision to go for the Corda.

OTH, Head-Fi is where I like to hang out (obviously). These bloody forums are totally addictive.

 

[Spad]

Quote:

Originally posted by M Rael I did a search of crossfeed many times Spad. Its a lot of opinion, as in the post at Headwize you pointed out. It contained, "What I want from a crossfeed circuit is to add a natural crossfeed effect without changing the sound otherwise." Thats not facts, thats preference. Ram, ram, ram, ba, ba, ba-ram. Thank you Brian Wilson.

You've certainly come full circle during this thread. In fact, all the way from "the Corda just uses delay" to practically the old "I knew it all the time" dodge. No matter how you get there, the result is the same and I'm glad you made it. Ain't ejjication a wonderful thing?

I wondered if you would pick up on my 'Beach Boys' mantra. You done good, SurferMan!

 

[kwkarth]

Quote:

Originally posted by jude [size=xx-small]It would be extremely difficult for me now to go without crossfeed (my experience is pretty much with HeadRoom's crossfeed only -- I used the Corda, but only very briefly at the Detroit show). Though crossfeed doesn't take the image out of my head, it does make listening far more natural to me than without it. I never thought I'd buy into the use of crossfeed until I actually received my Max and started using it. [/size]

I have to concur.

I have some "almost" binurally recorded material {eg. Nimbus NI7014-World Music Sampler Vol2} that sounds great when listening through an unprocessed amplifier system, but when I listened to the same material through the crossfeed system in the Headroom Max, the effect was literally astounding!

The psychoacoustic experience was SO much more convincing, I could hardly believe my ears! I like the effect so much that I also use the Max as a preamp to my SAC K-1000 amp so I can benefit from the Headroom crossfeed process when listening to my K-1000's as well!

I also have a Porta Corda which has a cross feed circuit, but I do not find the cross feed with it as desirable or compelling.

The cross feed in the PC strikes my ear as more of a simple stereo blending effect. i.e. It lessens the L-R separation, but doesn't seem to alter the phychoacoustic soundfield in any positive way.

So I tend to listen to the PC with cross feed off all the time, whereas with the Max, I find its cross feed effect so enjoyable and compelling, I tend to use it most of the time and with most material.

As far as headphone amplification itself goes, I became a believer a few years ago. I have used and enjoyed headphones professionally and for enjoyment for many, many years. Since the '60's actually. I've owned Koss Pro-4a, Pro-4aa, a couple pair of electret cans, several pair of the Sony MDR V6/7506's, Grado SR-200's, a pair of Sony CD-3000's, a pair of BeyerDynamic DT-250/80's, Sennheiser HD-414's, HD-580's, and HD-600's all before I bought my first headphone amp.

My first headphone amp was an attempt to obtain greater dynamic range and impact from some of my less efficient headphones. I auditioned a Creek OBH-11 and an OBH-11SE first and quickly discovered that a good headamp opened up completely new worlds of listening enjoyment for me. Not only did I achieve my goal of greater dynamic range and impact, but soundstage, the "black level" between instruments in the orchestra, the overall sense of realism and an innumerable list of other sonic attributes blossomed. Along the sonic journey, my headphone and amplifier inventory grew.

With each improvement in a new amplifier, the quality of each of my headphones also improved. I can truly say that I have realized decisively greater benefit and enjoyment from each of my current headphones as I have improved my amplifiers.

I would not hesitate to recommend a good headamp to anyone who enjoys music and headphone listening.

 

[dngl]

I've never heard headroom's crossfeed, but I don't like the Corda style crossfeed...

Headroom should release sound files of audio processed and unprocessed by their filter (just like Jan Meier did). Maybe they'd sell some statics...

 

[Spad]

Quote:

Originally posted by Jon Beilin I've never heard headroom's crossfeed, but I don't like the Corda style crossfeed...

Just out of curiousity, but what phones were you using with the Corda HA-1 and how long did the audition last?