[BiggerHead]

Replied too hastily, fixed.  Anyway, I think we're agreeing on one thing now, HTRC or whatever it's called only comes into play if microphones are involved.  We might be agreeing on the rest too.

 

[BiggerHead]

So I'll try again and see if I can get Joe Bloggs method (c) in context



Bootstrap technique

version a)

1) Get reference class speakers (in a reference class room).
2) Eq them so a sweep sounds flat to you.
3) Record the eq values.
4) Play this eq on your headphones.
5) Eq it further to sound flat
6) Record the HP eq values.
7) Subtract 3 from 6. This is your headphone eq.
The problem here is this works for graphic eq. For parametric, you'll have to subtract the eq curves and then try to parameterize that subtracted curve, which is maybe not so easy. Maybe good software can do this?

so version b)

1) Get reference class speakers.
2) Prepare tones at many frequencies so that they sound flat to you on the speakers
3) Play the tones on your headphones.
4) Eq the headphones so they sound flat.
5) Caveat, you probably have to take out small spikes before or after with sweeps like in the O.P.


Joe bloggs c)
1) Get reference class speakers (in a reference class room).
2) Eq them so a sweep sounds flat to you
4) Play this eq on your headphones.
5) Using a second equalizer, not touching the first one, eq this to be flat on your headphones
6) The second equalizer has your headphone eq in it. Remove the first equalizer and and enjoy your headphones.

(c is correct in my opinion but I'm only 70% certain it's what Joe bloggs meant)

Equal loudness curve technique

1) Play on your headphones a sweep or tones already biased for a generic equal loudness sweep at the right volume.
2) Eq that to sound flat on your headphones.
This assumes your personal equal loudness curve is reasonably generic, but it doesn't require reference speakers in a reference room.

 

[Joe Bloggs]

Yes, this is what I mean.

 

[BiggerHead]

Yay! 

 
This really isn't that complicated.  Flat sound is (edit) NOT (darn it) supposed to sound flat.  We make something that is supposed to sound flat using a system that sounds already like it's supposed to, and then we fix the headphones to make that sound flat on them too.

 

[castleofargh]

c) is pretty much a a) that is functional. I don't see the need for 2 solutions when it's the same thing. unless I misunderstood something, get rid of a).
 
and I don't really get what you're supposed to do with b). make one tone, compare it to 1khz, change the loudness and record it at that loudness? it looks super complicated for no real reason. seems like forcing the equal loudness contour into the tones instead of and EQ. I just don't see myself ever doing this.

 

[BiggerHead]

Right, a is maybe useful if you only have a hardware graphic equalizer and no software solution.  b probably isn't very useful since there is a free software solution for c.  c is indeed the best. 

 

[BiggerHead]

So we've settled on this:
 
JB bootstrap technique:

1) Get reference class speakers (in a reference class room).
2) Eq them so a sweep sounds flat to you
4) Play this eq'd sweep on your headphones.
5) Using a second equalizer, not touching the first one, eq this to be flat on your headphones
6) The second equalizer has your headphone eq in it. Remove the first equalizer and and enjoy your headphones.
 
Specifically Joe Bloggs uses Elictri-Q to create two software equalizers.
If you only had one equalizer you'd have to find a way to find the difference of two eq settings or possibly to prepare source tones in equal apparent loudness as input to step 5.

Equal loudness curve technique

1) Play on your headphones a sweep or tones already biased for a generic equal loudness sweep at the right volume.
2) Eq that to sound flat on your headphones.
This assumes your personal equal loudness curve is reasonably generic, but it doesn't require reference speakers in a reference room.
 
In a practical sense this second technique could be done in JB's way by programming the first eq with the generic equal loudness curve, and then tweaking a second eq as in step 5 of the first method.

 

[AudioBear]

== Equal loudness curve technique

1) Play on your headphones a sweep or tones already biased for a generic equal loudness sweep at the right volume.
2) Eq that to sound flat on your headphones.
This assumes your personal equal loudness curve is reasonably generic, but it doesn't require reference speakers in a reference room.
 
In a practical sense this second technique could be done in JB's way by programming the first eq with the generic equal loudness curve, and then tweaking a second eq as in step 5 of the first method.

I probably didn't say it right but the equal loudness technique is what I was driving at in my prior post.  Step 2 "to sound flat" puts our perceptions in place of an instrumental measurement and I don't see any way around that.  Thanks to all, the discussion has really helped so far.

 

[Joe Bloggs]

==
Equal loudness curve technique


1) Play on your headphones a sweep or tones already biased for a generic equal loudness sweep at the right volume.

2) Eq that to sound flat on your headphones.

This assumes your personal equal loudness curve is reasonably generic, but it doesn't require reference speakers in a reference room.

In a practical sense this second technique could be done in JB's way by programming the first eq with the generic equal loudness curve, and then tweaking a second eq as in step 5 of the first method.

I probably didn't say it right but the equal loudness technique is what I was driving at in my prior post.  Step 2 "to sound flat" puts our perceptions in place of an instrumental measurement and I don't see any way around that.  Thanks to all, the discussion has really helped so far.

Our way around this is to pre-EQ the tone sweep with the inverse of our perception biases (e.g. we perceive a 100Hz to be x dB quieter than a 1000Hz tone so we make 100Hz x dB louder in the sweep) so that your perception using the pre-EQed sweep matches instrumental measurements using a flat sweep.

 

[davidsh]

With SineGen it is possible to readily switch between 2 sine tones with a click. OP should perhaps look into that?
EQ'ing is indeed very complicated and full of trade-offs no matter what method you use, there is really no practically achieveable ideal, though each method will have pros and cons. I do, however, find the JB method as recently discussed quite appealing in general. Pick your poison.

Even using reference speakers in a treated room can't be considered ideal if you seek fidelity (due to stereo crosstalk and phase issues for example, among other things), and when done fussing over that there's the source material to consider too, which will be sub-par as well, which makes it a moot point doing any better than a reference class speaker setup.
Sometimes I entertain myself by trying to design/think out the perfect fidelity situation when playing back recorded sound, and consider viable approximations. My idea of fun

 

[BiggerHead]

By the way, there is no step 3.  Step 3 was just wrong.  

 

[Lunatique]

It should be pointed out that it's no trivial matter to "get reference class speakers (in a reference class room)," and unless you are willing to spend the time and money and do a lot learning about acoustics and acoustic treatment and room modes, it's very hard to achieve that goal. It took me many years to finally achieve it, and I've been at it since 2007 or so. In those years I read books on recording studio design/construction and acoustic treatment, asked questions on pro audio forums, corresponded with audio engineers who work for the company that manufactures the speakers, and went through lots of trial and error. 
 
The biggest obstacle to overcome is the room itself. Very very few people have a readily available room in their home that's suitable for critical listening, or can afford to (or have spouse permission) transform the available space into an ideal listening room. Too often the available listening space is severely asymmetrical in shape, layout, and/or have highly problematic acoustic properties (such as room dimensions that create severe room modes that even acoustic treatments can't do much about). In my first studio, I had to construct the room from the ground up as shown in these photos: 
 
http://www.ethereality.info/ethereality_website/about_me/images/workspace/cloud_pagoda/cloud_pagoda-design_construction.htm
 
In my current studio space, I had to take an open living room and build a new wall/door to close it off so I can get my studio space:
 
http://www.ethereality.info/ethereality_website/about_me/images/workspace/lincoln/finished/lincoln-studio.htm
 
(The entire left side of my current studio was originally open, with only a couple of support columns.)
 
And even having done all that, I still had room modes that could not be corrected fully. Acoustic treatment and room/speaker correction can only do so much if you have severe nulls caused by room modes.
 
The last bit of the missing puzzle was to add a subwoofer and then move the speakers as close to the listening position as possible (but still within the recommended distance), and make sure the speakers are far enough from the front wall so that rear reflection cancellation causing the null happened at a frequency lower than the crossover point for the subwoofer, so the subwoofer can fill in that null. (Meanwhile the subwoofer must be placed at an optimal position so itself isn't creating a null too). Only after having done this last bit, was I finally able to achieve a truly neutral/accurate sound.
 
So it needs to be said that one shouldn't assume that "get reference class speakers (in a reference class room)" is going to be easy. The only reason you should consider it is if you actually want a killer speaker system and a great sounding room to enjoy listening in, and are willing to spend the time and money achieving that goal. Otherwise, for just headphone EQ'ing, the method I described in my original post is plenty good enough. 

 

[Lunatique]

With SineGen it is possible to readily switch between 2 sine tones with a click. OP should perhaps look into that?
EQ'ing is indeed very complicated and full of trade-offs no matter what method you use, there is really no practically achieveable ideal, though each method will have pros and cons. I do, however, find the JB method as recently discussed quite appealing in general. Pick your poison.

Even using reference speakers in a treated room can't be considered ideal if you seek fidelity (due to stereo crosstalk and phase issues for example, among other things), and when done fussing over that there's the source material to consider too, which will be sub-par as well, which makes it a moot point doing any better than a reference class speaker setup.
Sometimes I entertain myself by trying to design/think out the perfect fidelity situation when playing back recorded sound, and consider viable approximations. My idea of fun

I explained in a previous post that pre-rendered sinewave test tones are more universal because they can be used with any device and platform as long as they can playback audio files. SineGen is great but it's not as universal across all platforms and devices. 
 
IK Multimedia's ARC System 2 corrects time-domain and phase issues too, not just frequency response. Take a look: http://www.ikmultimedia.com/products/arc/

 

[davidsh]

Can you get the software without measurement mic?

Presently, I use the free equalizer APO.

 

[Lunatique]

Can you get the software without measurement mic?

Presently, I use the free equalizer APO.

Without the measurement mic the software is useless, because the software is calibrated for the measuring mic that comes with the ARC System. All other similar products are the same as far as I know--they all come with their own calibrated measuring mics.