Revisiting "Imaging"

[eso]

...to which there has been discussion about whether the UREIs are actually time aligned since none of us has seen an impulse response of a UREI monitor, and now discussion of the Dunlevy impulse response (passive components) that is likely much better than the 40 year old UREI design.

Here's a page from a 1977 Urei catalog showing pulse and square wave traces...

I see my super Urei monitors linked again a couple pages back too.

And I also posted a new pair of 615B drivers with time aligned networks using the Don Patten circuit. It's basically the classic Ed Long TA circuit adjusted for the shorter offset of the 605 motor assembly. Whether or not those circuits are truly time aligned, they are a huge improvement over non-aligned notworks.

eso

[Robh3606]

Thanks eso!

Rob

[eso]

No, but I remember seeing one opened up on C/L and it was packed with caps and chokes.

Also, there are these for sale in Long Beach.

https://images.craigslist.org/00l0l_...2_1200x900.jpg

https://images.craigslist.org/00P0P_...M_1200x900.jpg

Those are one of my projects, currently residing in one of my son's rooms...

eso

[eso]

Thanks eso!

Rob

I thought I had a DownBeat article with more comprehensive test traces, but I can't find it right now.

In the examples below even though not stated I'd guess the competitors' are a stock 604 and a 604 with a mastering labs network...

eso

[toddalin]

Here's a page from a 1977 Urei catalog showing pulse and square wave traces...

I see my super Urei monitors linked again a couple pages back too.

And I also posted a new pair of 615B drivers with time aligned networks using the Don Patten circuit. It's basically the classic Ed Long TA circuit adjusted for the shorter offset of the 605 motor assembly. Whether or not those circuits are truly time aligned, they are a huge improvement over non-aligned notworks.

eso

These were the time aligned crossovers to which I was previously referring with all the chokes and caps. I see your ads on C/L.

BTW, ever seen the way Hammond delays the signal to create the "chorus" and "vibrato"? It's a bunch of chokes and caps to create a time delay with a scanner.

https://bentonelectronics.com/wp-con...2/vibrato3.jpg

[eso]

These were the time aligned crossovers to which I was previously referring with all the chokes and caps.

All of the Ed Long TA Networks for Urei used all the chokes and caps...

These are Urei circuits for:
811A (604 8K Ferrite)
original 813 (604 8G + helper Woofer)
811B (PAS 1580CX + JBL 2425)

The Don Patten circuit for the 605 is very similar the the "B" series networks.

eso

[Ian Mackenzie]

A follow up to my previous post.



I went over the a Stereophile Array 1400 review.

Below l have summarised some interesting observations.

1. The specified horn dispersion is 60 horizontal x 30 vertical dispersion pattern. On face value this seems to contradict the M2 140 x 100 dispersion while the DD67000 has a 100 x 60 dispersion.

2. The normalised vertical and horizontal frequency response shows a very smooth very smooth contours with slight fall off in the response above 10khertz.

3. The horn horizontal pattern control appears to be soft beyond the 60 degree specification.

4. The vertical pattern control is tight.

5. See comments by JA in attachment concerning the impulse tests. This confirms my earlier post. Specifically the 1400 Array's step response is at least time- coherent, in that the overshoot of the midrange unit's step smoothly leads into the woofer's step. This suggests an optimal crossover implementation. This validates my earlier post.

Conclusion
The Array horn appears to use the vertical diffraction orientation of the horn to maintain very uniform and extended dispersion. The sound stage created does not rely on a wide horizontal dispersion. Referring to JA’s comment while not time-coincident design (see impulse test) the fact that the ear/brain does integrate arrivals over a longer period than 1ms means this isn’t a problem in this design.

[Robh3606]

'Conclusion
The Array horn appears to use the vertical diffraction orientation of the horn to maintain very uniform and extended dispersion. The sound stage created does not rely on a wide horizontal dispersion. Referring to JA’s comment while not time-coincident design (see impulse test) the fact that the ear/brain does integrate arrivals over a longer period than 1ms means this isn’t a problem in this design."

Hello Ian

FYI not sure where in the review you saw 60x30 but that is not the case. The two horns are not the same pattern. The midrange horn is 80x80 the smaller HF horn is 60x30 look at the JBL Sam1HF tech sheet. The Array 1400 and SamHF1 use identical horns. The pattern on the mid horn is wider than you think based on any info in the review.

Rob

[Ian Mackenzie]

Hi Rob,

Thanks for the heads up.

I read it in the Array BG review here on the first page. See attachment and insights from Greg Timbers.

https://www.stereophile.com/floorlou...ker/index.html

I have attached the SAMHF spec as you referred to.

Interesting.

Between the lines l think the reviewer had a conversation with GT and there is somewhere an mis communication on the actual dispersion. Normally a manufacturer will prepare some technical editorial for a reviewer to publish. I say this because the “Listening Window” is +30 -30 in the horizontal plane according to the SAMHF spec sheet. Sounds like a mix up somewhere…

The measurements are what they are @ 50 “ on axis with the tweeter which is a normal procedure.

At 8 feet and 36 inches (averaged listening height) the measurement of the horn will look more like the curve in the vertical dispersion measurement @ -15 degrees down. It looks fairly smooth. (See attachment)

Therefore the measurements are meaningful. Of course it’s about the listening.

Edit attachment added with marked up horizontal dispersion (40 degrees off axis)
attached the vertical off axis measurement for discussion point in this post.

[Ian Mackenzie]

Just a broader way of saying the same thing. So then, what determines what is a good soundstage/image?

Would you want to listen to some "nebulous" bubble of sound floating infront of you, or a clearly defined space with width, depth, and height?

Good question. At least there’s one scientist in the crowd. (Todd is a scientist)

Looking at the examples posted it’s not about any one design element.

It might look like this

Low diffraction mid and hf baffle
Uniform and extended (HF) CD horn response with soft control angles
Group delay below perceivable levels.
A listening space which complements critical listening

But this is at odds with a conventional box loudspeaker.

It would look like an Ostrich…. The Linkwitz Pluto comes to mind.

That is why the Array as deceptively simple as it is works.

I don’t think working this out is like looking for the Dead Sea Scroll in a really long thread is the answer. People get fixated on catch phrases like Time Alignment and they go down a long endless rabbit hole look for the perfect answer. A time alignment only exists at one XYZ position in front of a loudspeaker. If that was the be all and end all of imaging we’d all have our heads in a vice. Clearly there’s more too it.

IMHO the best way to approach it is simply set your system up on your room as best you can following some credible guidelines and forget about it. Beyond that buy a pair of reputable near field monitors and use them for an imaging fetish. Attempting to buy or build a floor standing loudspeaker box that is the golden egg of imaging is a fantasy.

The best commercial examples look hideous and for that reason have not been a commercial success.

[1audiohack]

….A time alignment only exists at one XYZ position in front of a loudspeaker…

Unless you have something like the Danley SH50 Synergy Horn or another properly executed MEH horn.

Barry.

[toddalin]

I was listening to "Clapton Unplugged" on CD this evening. The placement of every instruments' amplifier was clearly defined across the soundstage (well beyond the speakers) and the interplay between the three guitar's strings was clearly audible on a note by note basis. Instruments, such as piano and voice are through the PA and panned into position. The piano is panned between the left speaker and left of center and you can hear the position change with the notes played. The soundstage is better than being there live.

You So Cal guys really need to get over here and hear this!

[Ian Mackenzie]

Unless you have something like the Danley SH50 Synergy Horn or another properly executed MEH horn.

Barry.

Hi Barry.

Maybe..🤔 I really admire Danley’s work.

Somewhere Don McRichie summed it up nicely.

The problem is that every time you uncover an unknown the there is another unknown and before long you become obsessed with listening to equipment instead of the music.
For example Dunlavy selected his drivers on the basis of them being close to textbook ideal. However a compression driver loaded by a horn is anything but the ideal. The phase, group delay and amplitude response is all over the place as you know. To correct that requires as you may know FIR dsp capabilities. It’s not without its downside in terms of setting up, complexity and cost. Then you have to say is my system and my situation going to make that sort of precision worthwhile. The only way is to assess it yourself after you’re absolutely certain it’s been implemented correctly. That’s another pain point that not many are prepared to endure. It’s all just too hard…Lol.

Some people might laugh but love playing a bit of Tina Arena in the truck…Lol.

It’s simple and it works.

Enjoy your weekend.

[Ian Mackenzie]

I was listening to "Clapton Unplugged" on CD this evening. The placement of every instruments' amplifier was clearly defined across the soundstage (well beyond the speakers) and the interplay between the three guitar's strings was clearly audible on a note by note basis. Instruments, such as piano and voice are through the PA and panned into position. The piano is panned between the left speaker and left of center and you can hear the position change with the notes played. The soundstage is better than being there live.

You So Cal guys really need to get over here and hear this!

Hi Todd,

I would love to. Next time I’m there. I need to do another tour via my friends in India, Thailand, Croatia, Iceland & Berlin…The last time l started in FS in CA and ended up at Windsor in the UK listening to Merlin’s system. Listening to someone else’s set up is really where it’s at. I think it enriches your appreciation of the hobby. Otherwise it can be a somewhat selfish pursuit. Helping someone by even being a sounding board is so fulfilling.

Can you a post a recording with wave file and stereo mics?

Btw has anyone heard from Clark lately? Clark hasn’t posted for a while. I recall visiting Clark and we did a trip down to catch up with Rick’s …. house of JBL cc 2007. It was a bit overwhelming looking at Rick’s 43XX enclosure production line.

https://www.soundseasy.com.au/produc...SABEgJPLvD_BwE

[Ian Mackenzie]

Oh on the feasibility of a coaxial or dual concentric driver the time alignment can only ever be set for one angle. This is because the delay required is specific to that angle. 😦 😥

In the overall scheme of things this isn’t the Achilles Heel of a co axial or dual concentric driver. They require acceptance of a number of often critical compromises for that on on axis point sources.