Timing Measurements

[Don Richard]

Basically, you have equipment that would make a good sound reinforcement system. It's not a surprise that it sounds good with bands that use similar equipment. I'll bet recordings of live concerts really rock with your gear.

[mark1101]

I barely listen to anything other than live music these days. 

[mark1101]

So due to reflections is there any advantage to HOW you align your speakers?  For instance, to a point in space in the room........to the front of the cabinets, or some other way?  I'm just wondering people's thoughts on the importance of the reflections and how they could affect alignment.

[Chris A]

I've found that placing the microphone one meter in front of the midrange-tweeter horn mouths works the best in terms of resulting phase curve accuracy and freedom from near field acoustic reflections.  Taking measurements too far away from the front face of the loudspeaker has always resulted in unusable phase measurements IME.  Using the REW SPL + Phase plot has worked very well for me. 

 

I also have used TrueRTA and simply played a sine wave at the center crossover frequency, then dialed the delay of the upper frequency driver plus and minus.  The summed signal coming from your speakers will tell you when you are dead on.  THis requires that you are within 180 degrees of alignment when you start.  Simple distance measure delay calculations work well as a starting point.

 

Then I use Audyssey to set the 5.1 channel delays from the listening position(s).  Averaging three microphone listening positions works well enough in my room.  This takes out all the differences in input delays from the various digital active crossovers plus the physical distance delays to each loudspeaker so that I don't have to guess.

 

When you see the combined impulse response of all channels doing it that way described above, you'll probably be impressed.

 

Chris

Edited August 19, 2015 by Chris A

[mark1101]

So you set the delay on the HF delay with Audyssey?  I'm not understanding the "input delays and various digital crossovers".  Can you explain that a little more?

[mark1101]

OK, from your edits I think I understand that you set the Jub HF delay via the methods you mention, and then incorporate the Jubs into a 5.1 configuration using Audyssey.  I assume your preamp is a multi-channel Pre/pro.

 

I get using the Audyssey to set the 5.1 for the theater experience.

[Chris A]

Yes, the 5.1 is used only after each loudspeaker is time-aligned (and EQed flat) for all drivers.  The microphone is set in front at one metre for each loudspeaker.  Then I use REW (or TrueRTA) to dial in the MF and HF delays to the drivers.  After I'm done with this step for each loudspeaker, I've got flat response and time-aligned drivers in each loudspeaker and sub.

 

Once that is done for all channels, then I use Audyssey in my pre/pro to set delays, making sure to turn off any "dynamic EQ", "EQ", or channel gains that it tries to set up. The Pre/pro also has it's own (non-Audyssey) pink noise channel loudness calibration function available on the remote control so that I can set the channel gains after doing any changes to any loudspeaker in the setup.  I can use a hand-held SPL meter (1 dB accuracy) or the calibration microphone with REW (0.1 dB accuracy) to set these gains. 

 

Since I've got three different digital crossovers/EQs, they each have slightly different input-output delays, so it's nice to have Audyssey to take out those differences without worrying if I calculated something incorrectly and guessed that I was in time alignment on all channels.  The only thing that I have to fix from Audyssey is the relative delay for the subs: since they're tapped horns, they have a precursor pulse that Audyssey likes to key on.  I have to add another 20+ feet of delay for the longer path through the horn.  Then I can check the delays between the bass bins and the subs out using REW.  It turns out that it's not very sensitive to delay settings since I'm crossing over at 40 Hz to the subs.

 

Chris

Edited August 19, 2015 by Chris A

[mark1101]

Can I ask what the other speakers and processors are and how you bi/tri-amp any of these?  Just wondering if every speaker in the 5.1 is actively processed and how you do that, or if just the front 3 are, or what it may be?

[Chris A]

The Jubs are bi-amped using a Yamaha SP2060 loudspeaker processor (which is the best I've heard: 24/96 internally), the center JuBelle (K-510/K-69-A, CP25 tweeter) is tri-amped using a Dx38, and the surround Cornwalls (Crites tweeters) are biamped using a Dx38, and the subs are using mono-mode XTi-1000s (one each).  That's all 6 channels. All channels are time-aligned and EQed using loudspeaker processors/DSPs.

 

Except for the subs and the TAD TD-4002 channels in the Jubs, all channels are powered by Crown D-75As.  The TADs are powered using a First Watt F3 (JFET) amplifier to drive them--which is a very nice sounding amplifier.  All connections are balanced (XLR) except to the First Watt - which uses an XLR-RCA cable to connect. 

 

The preamplifier is an Onkyo PR-SC886, which I have been very pleased with.  I've thought about alternatives to this preamp--going "hi-end" so to speak, but at the end of the day, it's the best solution that I can imagine having DACs that really can't get any better and good processing that I can control to turn off everything that I don't need.  It also serves to decode the input streams from an Oppo BDP-103 (playing discs, Netflix streaming, YouTube, etc.), a Sony PS3 (only streaming Amazon Prime), and a laptop playing foobar2000 flac files--which is where I do all my remastering/unmastering work using a small Western Digital 1 Terabyte USB HD to hold my entire disc track collection.  All input connections to the preamp are HDMI, including the output from my laptop, but with the exception of a turntable with an external phono preamp that I route through an analog aux port in the preamp--which mostly is gathering dust while I remaster my digital track library using Audacity.

 

The preamp uses balanced XLR output connections to the five loudspeaker processors (SP2060, two Dx38s, two XTI-1000 DSPs), which means it's very quiet without common mode (60/120 Hz) hum.  It also has Audyssey in firmware, which I use only to set the channel delays, mentioned above.  The preamp also has software adjustable channel gains and digital delays that are used to time-align the 5.1 array and to set channel gains using pink noise and an external SPL meter or calibration microphone using REW.  The preamp also routes video from the input devices and does the video/audio channel sync as a function of input device.  It's a snap to use once you figure out the functionality.

 

I have a procedure that I use to set up all channels, but the basic process is the one that I described above.  Once I got everything dialed in, it's been fiddle-free.  I enjoy the music and remastering now many hours/day.

 

Chris

Edited August 20, 2015 by Chris A

[mark1101]

I'll bet your wife loves you for all that. 

[mark1101]

Once I got everything dialed in, it's been fiddle-free.  I enjoy the music and remastering now many hours/day.

 

Chris

 

One more point.........it's a little sad isn't it that there is nothing to play with now?  My system is the same way.  Lots of initial setup, but once done I haven't changed any settings in a year or two. It's simply runs itself and nothing to fool with but the volume control.   I just listen to music now like you do.

 

If it weren't for my other systems that I play with I'd be out of the hobby of playing with equipment which I enjoy very much.

[Chris A]

(Chuckling to myself as I write this...)  I don't mind at all having a stable and maintenance-free system: that was a prime objective.  If I wanted to fiddle with things, I'd do the audiophile thing and really get into turntables, cartridges, vinyl cleaning machines, tube rolling, and other such nonsense.  I hate working on cars, fixing plumbing, electrical systems, roofing, fences, etc.   I've got reasons why--but I'll spare you. 

 

I'm really just a music lover that prefers spending my time listening and not fiddling--at least with hardware.  I'd call it a basic obsession with music that music school didn't get time enough to drum out of me (pun intended). 

 

However, the invention bug has recently bitten and I'm now plotting new madness via novel loudspeaker design.  Stand back when you notice a blue flash...it'll probably be a criticality event.    

 

Chris

[Bossman]

For Khorns, I physically aligned my mids and tweeters and it helped. This is the lowest they can be with a slight tilt without having effects of hitting the top of tophats. The drivers are now horizontally and vertically aligned on top. They are VoltiT1 tweeters. We have made blindtests and everytime we ended up prefering this to tweeters being in the tophats to the sides (volti upgrade fits inside tophats like that). Here are two photos:

Hi Kodomo, I have done similar testing with aligning the tweeter to the mid as you have. I think the difference is quite noticeable. It is very irritating receiving sounds produced from the tweeter before the midrange. I notice this effect more when the tweeter horn has a more narrow dispersion pattern than the midrange, especially when combining a large midrange horn with 90 to 100 degrees horizontal and more than 60 vertical with a tweeter that had a 40 degree conical dispersion. Last week I started a new 3-way horn loaded speaker build with the emphasis on time alignment because of the issue.  A member replied with the delay the specs in milliseconds, and this may seem like a small measurement, but it makes a big difference in sound. 

[Bossman]

 

Time aligning the drivers really doesn't seem like an option.

Because...?

 

You can time align the midrange-tweeter easily by removing the K-77 tweeters from the cabinet and placing them on top of the loudspeaker, centered at the back of the cabinet, approximately aligned with the midrange driver (K-55) below it.

 

Moving the tweeter fore and aft on top of the cabinet, you will hear it come into focus when the time alignment occurs.  From there, you can listen and determine whether or not it's worth your time to place the tweeters in small baffles, like Bruce did with his replacement tweeters (top picture).  It's this midrange-tweeter crossover time misalignment that has the greatest effect on the sound of the loudspeaker. 

 

While I actually do not recommend removing the midrange horn/driver from the cabinet due to the benefits of clamping the midrange horn mouth to the front baffle to eliminate ringing, I don't see any reason why you couldn't simply rest the tweeter on top of the cabinet, like Michael (Thaddeus) did in the bottom picture, but aligned with the midrange driver below it.  This actually has more benefits in terms of eliminating the "looking through the baffle" effect of having the tweeter mounted to the rear side of the front baffle thus improving its polars.  You can also turn the tweeter vertically to get slightly better horizontal coverage performance (...in fact ElectroVoice's recommended orientation).  Simply put something absorbent on top of the cabinet to absorb the reflections off the top of the cabinet, and you're good to go.

 

 

One should consider the dispersion pattern of the tweeter horn to prevent sound waves from hitting the surface they sit on. This can be a upgrade to an upgrade.

[Rudy81]

 

Once I got everything dialed in, it's been fiddle-free.  I enjoy the music and remastering now many hours/day.

 

Chris

 

One more point.........it's a little sad isn't it that there is nothing to play with now?  My system is the same way.  Lots of initial setup, but once done I haven't changed any settings in a year or two. It's simply runs itself and nothing to fool with but the volume control.   I just listen to music now like you do.

 

If it weren't for my other systems that I play with I'd be out of the hobby of playing with equipment which I enjoy very much.

 

 

I must say I'm in the same boat.  I have not fiddled with my system since I finished all the alignment work, finished my room treatments and ran Audyssey Pro one last time.  Since then, either I got tired of messing with things, or I found the best compromise for my room.  It all sounds 'right' to me and I now just sit, listen and enjoy.

 

Very long journey as some of you know, but I am thrilled with the results.  Only thing that might be left is to upgrade my Oris horn drivers, but I just can't justify the huge expense for that set of drivers.  I'm not really sure it would make that much difference. 

[DrWho]

What's wrong with a 6 cent opamp if it meets the performance goals? Cost is not an audible parameter....

That said, you're totally right about a lot of products using bad opamps, but there's a lot more to it than throwing money at something. It's not hard to have a cheaper solution sound better than an opamp with unnecessary features...

[djk]

"What's wrong with a 6 cent opamp if it meets the performance goals? Cost is not an audible parameter...."

 

I guess my performance goals are a bit higher than most gear on the market.

 

I like the way DBX uses cheap parts where they can get away with it, and better parts where they can't. I call that value engineering.

 

I designed and built a LR24 crossover in 1981 that was built this way, it used the RC4136 in the non-critical areas, and the TL075 and TL071 in the critical areas. DBX did this in a crossover they currently make, LF347 (junk) and TL074 (OK).

Edited August 22, 2015 by djk