• QuadraphonicQuad welcomes you and encourages your participation! Treat all members with respect. Please keep all discussions civil, even when you have a strong opinion on a particular topic.

    Do not request or offer for sale or trade copies or files of copyrighted material - no matter how rare or unavailable to the public they might be. We do not condone the illegal sharing of music. There are many places on the internet where you can participate in such transactions, but QuadraphonicQuad is not one of them. We are here to encourage and support new multichannel releases from those companies that still provide them and as such the distribution of illegal copies of recordings is counter-productive to that effort. Any posts of this sort will be deleted without notification.

    Please try to avoid discussions that pit one format against another. Hint for new users: make liberal use of the search facilities here at QuadraphonicQuad. Our message base is an incredibly rich resource of detailed information on virtually all topics pertaining to surround-sound. You will be surprised at what you can find with a little digging!

"Fixing" the Jeff Beck Group's Rough and Ready quad (Sony SACD)

Frogmort

700 Club - QQ All Star
Joined
Dec 20, 2013
Messages
941
Likes
779
Location
Frogmorton
#21
Off topic again, as usual, but I just wanted to say that I was just funnin' with ya Ol' Jim. Didn't mean any disrespect at all, was just trying to be funny while catching a buzz, but I noticed today that that I might've come across as a bit of a douche, and I'm sorry for that.

I'm still fascinated by the idea that you found the left front speaker to be 1 millisecond off for the first 5 tracks though. How does one end up in a situation where they can notice and then measure such things?
 

Jim the Oldbie

400 Club - QQ All Star
Joined
Jun 6, 2015
Messages
598
Likes
403
Location
Midwest USA
#22
It's all good Froggy, really! That pic was actually pretty funny; I shoulda counted to ten before replying.

I just got back and I'm tired as hell, but I should have time tomorrow to add some more details.
 

Jim the Oldbie

400 Club - QQ All Star
Joined
Jun 6, 2015
Messages
598
Likes
403
Location
Midwest USA
#23
Here's a few more details:

As mentioned earlier, I really really like all this old Jeff Beck stuff, so I ordered these SACD quad discs as soon as possible. But I was kinda disappointed when Rough and Ready arrived. I don't have perfect pitch, but it's close enough that the speed errors on the first 2 tracks really bugged the crap out of me, right out of the gate. "Got the Feeling" was off by a noticeable amount, but the next track was worse - compared to the old familiar stereo mix I'd been enjoying for 45 or so years, "Situation" was sharp by a full half-step musically, and there was an obvious giddy-up in the tempo as well. Plus, whats' with this center channel? They didn't bother with that for the Orange album quad, and it sounds fine without it?!

At the time I had no means to rip SACDs, so there was nothing I could do to correct any of this. For awhile I was looking at used Playstations, but that search eventually trailed off, and Rough and Ready began to gather dust... (sniffle)

More recently, when those kind and clever souls out there came up with the BD player hack, I picked up a Pioneer BDP-80FD and started not only ripping all my SACDs, but buying more of them like crazy! Get it, Mr. Record Industry Guy? If you let me back up the software I purchase from you, I will purchase more of it! What a concept!

<ahem> Sorry. Moving on:

At some point during this process I realized that I could blow the dust off of Rough and Ready, load my multichannel FLAC files into Audacity to fix the speed errors on tracks 1 & 2, and maybe figure out what was going on with that manufactured center channel. But then I noticed some other stuff.

It turns out that if you're using Audacity on a typical computer setup with 2-channel audio (like mine), when you load a multichannel file, by default it pans all the channels to the center of the stereo monitor mix that you hear when you hit the Play button. (It also sets each one to 0 dB, which then severely overloads the mix buss, frequently causing instant distortion, but I digress.) So you wind up with your 5.1 or whatever mix all glommed together in the center. But this can sometimes be very revealing. As soon as I hit Play on "Got the Feeling" and listened to Cozy Powell's classic intro, I noticed the telltale sound of comb filtering in this mono mix.

As you may know, comb filtering is what happens when a sound (or any signal) is mixed with a time-delayed version of itself (or something close, such as the other channel of a left-right stereo pair). This creates a complex pattern in the resulting frequency spectrum plot that resembles the teeth of a comb. In audio, if the delay time is in the proper range, it can impart a distinctive hollow-sounding "pitch" to the combined sound. The frequency of this perceived pitch is simply the reciprocal of the delay time. For example: If the delay time is about 2.3 milliseconds, the "pitch" of the filtering effect will be roughly 440 Hz (or Concert 'A' in musical terms), since 1/.0023 = 440.

Audio comb filtering is best known as a studio effect called "reel flanging," where the delay time is swept up & down to create that classic jet-plane sound we all know & love. One fine early example is the most excellent 1967 hit single "Itchycoo Park" by Small Faces. (As a side note, "Itchycoo Park" is also an example of reverse-polarity flanging, where the polarity of either the direct or delayed sound is flipped; this emphasizes a different harmonic series and creates a variation of the effect that is rarely heard!)

When the delay time is constant and not moving (and in the audible range), it sounds like a flanging effect that is "stuck" on one pitch. When I first listened to Audacity's mono mix of "Got the Feeling," I heard the characteristic hollow-pitch sound resonating at about 1000 Hertz. As above, 1/1000 = .001, so I knew that at least one of the channels in the mix was off by 1 millisecond. But which one was it?

OH shit. I do blather on, sorry. I gotta go fix the porch light before it gets dark, so I'll be back with more later. I just hope I remember to take off my tinfoil hat before I go outside, hee hee!! ;)
 
Last edited:

Jim the Oldbie

400 Club - QQ All Star
Joined
Jun 6, 2015
Messages
598
Likes
403
Location
Midwest USA
#24
(Okay, no more tripping & cursing on the porch steps at 2 AM, yay!)

To isolate the delay problem described above, I started listening to channels two at a time. The first logical choice was front left & right, so I muted everything else and had a listen to them alone, and there was that hollow sound. Then as soon as I muted one channel and listened to the other alone, the sound returned to normal - this is a dead giveaway that comb filter cancellation is occurring.

The next step was to determine the delay time. One quick way to do this is to flip the polarity of one of the two channels being compared. Then, as you adjust the delay time of one channel, any common components (mostly stuff that's panned midway between the channels) will begin to cancel as you approach time synchronization. Using the "pitch" described above as a clue, I began by delaying the right front channel by 1 millisecond, and immediately got lucky - Bob Tench's center-panned vocal nearly disappeared. I then fine-tuned the delay for maximum cancellation, and found that it occurred at exactly 102 samples @ 96 KHz, the sample frequency of my converted PCM file. This corresponds to a delay that's actually a little longer than 1 msec, which would be 96 samples. But the difference is so small that I would recommend using the 1 msec correction instead, since this figure is the same at any sample rate.

After applying the delay to the right front (and un-flipping the inverted channel), the full mono mix sounded normal again - the hollow, "stuck flanger" sound was gone. Problem solved, I thought. Well, not so fast. After applying the same fix to track 2, "Situation," the hollow sound was still there! So I started comparing the first & second tracks, trying to find differences in the mixes that might provide clues.

I found that track 1 has essentially no common sounds between the front and rear - each instrument is located fully at one location or the other, like a quad version of the old ultra-stereo sound from the '60s. But track 2 is different: Beck's guitar is actually panned part way between the front and rear on the right. Since I'd delayed the right front channel to match the left front, they were both now out of sync with the rear! I hadn't noticed this on track 1 because there were no common sounds between front & rear to create the comb filtering sound in the mono mix.

I then realized that I'd been looking at the whole problem backwards, or sideways, or something. Obviously the left front was the only one that was inadvertently delayed, so the solution was to delay all the others to match, not just the right front. This eliminated all traces of comb filtering on the affected tracks. Oddly enough, as I went along through each tune, listening and then applying the fix, when I got to track 6, "New Ways Train Train," the delay problem disappeared! That track is a little phasey-sounding in mono, but there's no actual time delay problem - there are also quite a few noticeable dropouts on this track, so I think the master tape might just be showing its age here. And the final track, "Jody," sounds fine without any adjustments - no comb filtering detected.

One obvious question at this point is: Who cares how this sounds as a big ugly mono mix? We don't actually listen to it this way! And it is true that when the channels aren't being mixed together, the interchannel time delay is no longer audible as comb filtering. But it still exists, and it still has an effect on the sound we hear. In stereo for example, our 1 msec delay is enough to blur the soundstage, particularly the phantom center channel. Remember that 1 millisecond is the time it takes for sound to travel approximately 1 foot at sea level. (This might be different on Snood's planet of course - hey Snood, wake up!) With this in mind, imagine the typical center-panned lead vocal. Even though it's coming from the two left and right speakers, it appears as a single sound, hovering in the space between. Then imagine that single sound being sort of "pulled" into two sounds, spaced about a foot apart from each other. That's a fair description of what a 1 msec left-right delay sounds like. It's not a disaster, but it definitely sounds better if it ain't there!

But wait! Isn't this minor tweak kind of pointless? Because, don't all HT receivers have adjustable delay settings, to "correct" the arrival time for each speaker (usually by a lot more than 1 msec)? Yes they do; and in my opinion, these adjustments do more to screw up the sound than fix it. They do indeed allow you to synchronize the arrival times of the direct sound from each individual speaker to your noggin, at one listening location. But that's only a part of what we're hearing. There is also the multitude of reflected sound in the room, arriving at myriad different times, from different directions. If you set different delay times for each speaker to fix the direct sound, the reflected sound then becomes decorrelated, which not only sounds screwed-up in its own unique way, but is also screwed-up everywhere in the room. A fair argument is that this chaotic reflected sound is already decorrelated, or that it just isn't as important as the direct sound; but I submit that this is not entirely accurate. I've done a fair bit of experimenting with this over the years, and to me, the sound is always more cohesive and "right" when I don't use any delay time compensation. There are cases (such as a really asymetrical speaker placement) where this feature might fix more than it hurts, but if this isn't the case, you might want to try setting these adjustments to zero and letting everything happen at the same time, to see how it sounds. You may be surprised.

Kudos and a hat-tip to anyone who has actually read this far. Sorry for droning on. I'll finish with a quick recommendation for the center channel: Delete it. Like I said above, it's just a mono mix, which does nothing but compromise the original quad separation. Plus, it has that damn comb filter sound on the affected tracks, and there's no way to fix it here that isn't way too complicated. I think the whole mix sounds much better without it.

- Jim
 

winopener

1K Club - QQ Shooting Star
Joined
Mar 2, 2002
Messages
3,087
Likes
183
#26
So, in short:
1) split any song file into separate channels
2) delete all center channels
3) for track 1 to 5, apply delay 1ms to FR LR RR
4) don't touch track 6 and 7
5) recombine everything.

Correct?
 

Jim the Oldbie

400 Club - QQ All Star
Joined
Jun 6, 2015
Messages
598
Likes
403
Location
Midwest USA
#28
So, in short:
1) split any song file into separate channels
2) delete all center channels
3) for track 1 to 5, apply delay 1ms to FR LR RR
4) don't touch track 6 and 7
5) recombine everything.

Correct?
Yup - along with the speed changes on tracks 1 & 2 as described earlier, that's all of it.
 

fredblue

QQ member number 4041
Joined
Mar 30, 2009
Messages
18,992
Likes
2,079
Location
London, England
#29
you're welcome :) I was surprised too, I haven't had recourse to play the SQ record since the SACD came along! we'd need to check a copy of the Q8 to be sure (I don't have it sadly) but it seems the speed issue may be inherent in the Quad mix rather than a tape transfer problem by Sony Japan etc.
 

Q-Eight

1K Club - QQ Shooting Star
Joined
Sep 30, 2003
Messages
2,728
Likes
328
Location
Castlegar, BC, Canada
#30
Sounds like they sped up the stereo versions but the multitrack runs at "as recorded" speed. This has been the case on countless pop tunes over the years. The Doors and Paul Revere & The Raiders have songs that were sped up by doing the old "tape on the capstan" trick.
 

fredblue

QQ member number 4041
Joined
Mar 30, 2009
Messages
18,992
Likes
2,079
Location
London, England
#31
Sounds like they sped up the stereo versions but the multitrack runs at "as recorded" speed. This has been the case on countless pop tunes over the years. The Doors and Paul Revere & The Raiders have songs that were sped up by doing the old "tape on the capstan" trick.
the Stereo of the 1st two tracks is slower than the Quad
 

Jim the Oldbie

400 Club - QQ All Star
Joined
Jun 6, 2015
Messages
598
Likes
403
Location
Midwest USA
#32
As an epilogue to this project, I just remembered that this isn't the first time this title has had mastering issues.

When Rough and Ready was first released on stereo CD, I immediately special-ordered a copy at my local record shop (there was no internet at the time, heh). When it arrived, I discovered that the mixes were completely different from the LP - they sounded unfinished, like demos or something. Interesting, but not nearly as good as the original release.

So I called CBS/Epic about it. Eventually I was connected to someone apparently in charge of such things, who sounded like he had no idea what I was talking about. I had to patiently explain several differences between this CD and the LP, which he duly noted, and said someone would get back to me on it! Yeah, right, I thought. But sure enough, a few weeks later I got a letter in the mail saying that this title had been corrected, and I could send in my "defective" version for a free replacement. So I did, and the new one had the proper LP mix.

Thinking back on it now, I wish I would've kept the weird one. I should've just waited awhile, then picked up the correct version sometime later after it got sorted out. Oh well...

JB_RAR_NewVersion.jpg
 
Top