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Chris A

Double Stack ESS AMT-1 with Wings--Possible Kit for Heritage

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Well, I have some homework to do. My frequency response is pretty flat throughout the audible range, but my phase looks like a tightly wound spring!

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2 minutes ago, No.4 said:

Well, I have some homework to do. My frequency response is pretty flat throughout the audible range, but my phase looks like a tightly wound spring!

 

Not to point out the obvious, but have you unwrapped the phase plot?

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2 minutes ago, Rudy81 said:

 

Not to point out the obvious, but have you unwrapped the phase plot?

No. That is a component of REW I have not played with very much.

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42 minutes ago, No.4 said:

No. That is a component of REW I have not played with very much.

Working on it now though!

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Unless I have this wrong. After you take your REW sweep.  Click on the 'Controls' wheel. Click on 'Estimate IR delay', click 'shift IR' in the dialog that opens. Then, click 'generate minimum phase', and then 'unwrap phase'.  You should then be able to look at the phase and GD plots for what we are looking for.  The Spectrogram defaults need to be modified to give you the screen I posted earlier.  In one of @Chris A posts, there are explanations on doing this.  Hopefully, I have given you the correct info.

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@Rudy81 yes I have gotten that far. I was going through trying to decipher what adjustments i need to make to my delay time.  I did re run sweeps and adjust PEQs though now that I have the drivers at an angle. The phase and spectrogram look better to my eyes now with adjust PEQs. The sound is great to my ears as it is, I’m just curious how much better it could be.
 

The ability to fine tune any speakers using these tools is really impressive. I am just pushing through the learning curve.

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2 hours ago, No.4 said:

@Rudy81 yes I have gotten that far. I was going through trying to decipher what adjustments i need to make to my delay time.  I did re run sweeps and adjust PEQs though now that I have the drivers at an angle. The phase and spectrogram look better to my eyes now with adjust PEQs. The sound is great to my ears as it is, I’m just curious how much better it could be.
 

The ability to fine tune any speakers using these tools is really impressive. I am just pushing through the learning curve.

 

I feel exactly the same way.  I tweaked the system for the last two days and have done as much as I know how to do in my limited knowledge base.  Sounds awesome to me right now.  I'm always willing to try and improve things, but I have reached my limit for now.  Going active most certainly gives one a thousand ways to improve and modify one's system.

 

One thing I have learned over the years is that every time I feel I've reached great sound, I later find something just a little bit better.  For example, the case of going from six years with my Oris horns....until I found out and tried the Heil AMT!

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39 minutes ago, Rudy81 said:

One thing I have learned over the years is that every time I feel I've reached great sound, I later find something just a little bit better.  For example, the case of going from six years with my Oris horns....until I found out and tried the Heil AMT!

did this about 7 years ago when I refurbished an AMT-1A speaker I found on Ebay that was only 1 mile from my house in Indianapolis (I had a job there for about a year) when I lived there for about 1 1/2 years. I have moved 8 times in the last 11 years, so aside from messing around with Klipsch and other brands of speakers and components, I'm really glad I've settled down into my little old house. As long as I can keep women out of here a while longer, I should have all this done.

 

First time I hooked up the ESS speakers (new woofers, diaphragms, passives, etc.) with the original passive Xovers, I was blown away by the 3D sound I got from the 40 year old technology. Now that you have gone FULL OB on your setup, I can only imagine how good this "super tweaked double tweeter" setup sounds. I'm glad to see so many of you doing all this R&D featuring Heils, which were as great of an invention as a HORN for home sound reproduction!!

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A noob question, but here it is:

how well would double stack EES go with big bass horns, such as MWM, Quarter Pie or Super MWM (of course active)?

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The real issue that I see (including the Khorn bass bins and to a lesser extent, Belles or Peavey FH-1s) is the higher frequency cutoff and polar coverage of the "W" section bass bins.  The Quarter Pie design uses a single horn mouth, so it doesn't have the two-mouth diffraction lobing issues of the "W" sections, and only has a 90 degree turn in the horn axis.  Here is a SPL response plot of the MWMs, KPT-305s, and K-402s that mark1101 posted some time ago showing the roll off of the MWM response on-axis above 200 Hz:

 

MCM-4.jpg

 

Here is the raw in-room (on-axis) SPL and phase response of a Belle Klipsch bass bin showing the roll off of SPL and phase growth above 250-300 Hz, where the polars of the bass bin also begin to significantly narrow:

 

1867384983_BelleBassBinSPLandPhaseResponse--QuarterSpace.thumb.jpg.754d840cfe268a25b6439b34fa72d17f.jpg

 

The reason why La Scala bass bins work so well with AMT-1s (I infer) is the high frequency extension and on-axis SPL response of them goes to at least 1.2 kHz before on-axis SPL begins to succumb to the effects of horn folds and "mass corner" effects of the woofers themselves at high frequencies above 400-500 Hz.   This is due primarily to the full mouth closure of the La Scala bass bins without dual mouth truncation that results in a flat baffle in between the two mouths. The La Scala bass bins fully close the two horn mouths from the "W" section horn into a single horn mouth. 

 

If you are willing to live with narrowing polars of the bass bins above ~200 Hz and boosting EQ above 200 Hz on the MWM, SMWM, Khorn, FH-1, or (to a lesser extent) Belle bass bins, these can be used with the double-stack AMT-1s, and crossed carefully at 550 Hz (with EQ boost).  The bass bin polars will be very narrow up high in frequencies, but the on-axis SPL response can be EQed flat very easily. 

 

Chris

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On 6/26/2020 at 6:14 AM, Chris A said:

 

...The reason why La Scala bass bins work so well with AMT-1s (I infer) is the high frequency extension and on-axis SPL response of them goes to at least 1.2 kHz before on-axis SPL begins to succumb to the effects of horn folds and "mass corner" effects of the woofers themselves at high frequencies above 400-500 Hz.   This is due primarily to the full mouth closure of the La Scala bass bins without dual mouth truncation that results in a flat baffle in between the two mouths. The La Scala bass bins fully close the two horn mouths from the "W" section horn into a single horn mouth...

 

Chris

 

Hmmm, I'm surprised the Peavey has the narrowing polars you describe since it doesn't have the flat baffle in between the two mouths.

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Sorry, I had confused the Peavey FH-1 and FH-2 with the EAW BH 882 (the reason for the nose extension credited to Larry Levan--actually designed by Richard Long & Associates )

 

1809550794_EAWBH882.jpg.c19d41e0badf5de9c48bef3ab805f418.jpg

 

Chris

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thanks for clarifying that Chris. Sounds like my FH-1s might be good to try with an AMT-1 double-stack

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What's the latest from ESS? You guys finally get your parts/replacements or are they still dealing with stock issues?

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My replacement diaphragm is working just fine, so have not been in contact with ESS for a while.  Still loving the Heil sound!

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-   Hi Chris , I was wondering if you could clear something up  for me, I was talking - well emailing back and forth with a honest to goodness professional speaker designer the other day, and I was trying to explain the great results everyone here is having,  and how much they were enjoying with their stacked AMT's and the comment I got back was that it wasn't a good idea to stack those tweeters because it would cause comb filtering between the Amt tweeters,  and I didn't really know what to say back... do you know if that is a problem or not?   --  Thanks, Dean

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Since the gap between the diaphragms with stacked AMTs is so small, and the reward of using the AMT-1s over the separate K-77 plus K-55 and its midrange horn is so much greater, better is better--a lot better.  If you look at the polars due to separate tweeters and midranges used in the Heritage loudspeaker models, you will not have any problem choosing the stacked AMT-1s.  The "get" is better in every respect vs. the stock drivers (except one-vertical coverage angle). 

 

If you want to solve that last issue (vertical coverage), you'll need a K-510 horn and a dual diaphragm 2" compression driver to beat the stacked AMT-1s, and then you lose the dipole artificial depth of soundstage of the AMT-1s.  The transient response of the dual diaphragm compression driver is almost as good as the AMT-1s, but not quite equal.  Of course, at the prices charged by Klipsch for doing the K-510 and a third-party driver, and then having to dial in the driver yourself, that trade off is not nearly as attractive as the AMT-1 (stacked) solution.

 

I really like how people dismiss these kind of ideas--like a knee-jerk without thinking about the problem space, and without listening to it.

 

Chris

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Stacking AMTs will cause both comb filtering and serious vertical lobing. That's simply physics with large center og center spacing, thus "small gap" doesn't help much here. How much that bothers people probably depends a lot on references and what's being compared to as well as the benefits. Almost all commercial speakers suffer from this to various degrees. It's something best to try out and hear for yourself.

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47 minutes ago, Bjorn said:

Stacking AMTs will cause both comb filtering and serious vertical lobing. That's simply physics with large center og center spacing, thus "small gap" doesn't help much here.

What Bjorn hasn't said is that when you compare the stacked/winged AMT-1s against what all Klipsch Heritage owners have currently (separate tweeters and midranges), this part of the performance is shifted by at least two octaves higher due to the very small gap between the stacked diaphragms (and most probably out of the frequency range that most people will ever sense or be aware of).  Conversely, if they sense this issue now, no one would own any three-way loudspeakers with separate tweeter apertures from the midrange apertures--or loudspeakers having vertical arrays of small drivers in a line array (like the expensive McIntosh loudspeakers, etc.)

 

McINTOSH_020118_gnzphoto-1690-edit.ashx

 

I'm not sure why you've fastened on this particular aspect of the stacked/winged AMT-1s, but it certainly isn't one of the trade-off areas  that I'd pick.  You've also failed to quantify the magnitude of the issue, which in my estimation is "in the noise" compared to all the issues/audible defects that are present in the stock configurations. 

 

To @hallcon83, one of the characteristics of a good engineer is the ability to weigh the pros and cons of each design, especially from the standpoint of price/cost, and balance the good vs. that which you give up.  In the present case, you're giving up nothing but vertical coverage vs. stock Heritage components, and gaining a lot in more than one area of performance.  (You should hear the difference.)  And you're doing this at low cost.  That's called a no-brainer from where I come from. 

 

Since the people that have tried this configuration and like it and have stayed with it speaks for itself, I stand by my comments, above. If the whole world is nothing but vertical polars, I've already discussed my approach to that solution (a much more expensive solution).  But I would guess that 90-95% of the people listening to the two configurations (stock vs. stacked/winged AMT-1s) and then look at the relative prices, its a no-brainer.  Most people want an upgrade to what they've already got.  The stacked AMT-1s are a big upgrade. 

 

Chris

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