AR Bi Amp Hybrids (ActiveXover Stacks) CR65, AR581w, AR51w, AR358s, AR98T

[ligs]

I am pleased that a question on my part can shake up something on your end. 

 

George

[ligs]

Removing the deep bass(like you did with AR58) tends to improve the linearity of a woofer and the clarity of the overall sound. A case in point is when playing LP, we will notice the excessive movement of the woofer which robs the power of the amplifier. But after engaging the subsonic filter, we can play the same speaker louder and cleaner. 

I remember one of the more salient features of AR9 is its exceptional power handling capacity. Not only the 8" LMD does not have to produce the deep bass, the pair of 12" subwoofers are driven through a special crossover network containing  a large capacitor to serve as a subsonic filter.  

[Aadams]

On 8/5/2019 at 7:50 AM, ligs said:

Removing the deep bass(like you did with AR58) tends to improve the linearity of a woofer and the clarity of the overall sound.

Ligs

Yes, it works. As you know, the phenomenon has been known for decades and some expensive full range speakers such the AR9 take advantage of it.   It can also be done with powered sub woofers and satellites.  What I have found is an 8 ½ or 9 octave three way such as the 12" AR three ways do not achieve equal clarity over the same range as a similar quality system with a low bass crossover in which the woofer carries very little of the human voice.

As a standalone system to compete with modern home speakers, which are mostly 7 to 8 octave two ways, I would say a properly functioning AR5, 12, or 92 set out away from boundaries, 30” off the floor, would be easily comparable and cause much less of a fuss than the 3 way 12”.  If the last octave of bass is requirement then of course the AR 12” is a bargain but you sacrifice accuracy in most situations because 12” ARs are almost always placed to achieve bass, subject to WAF constraints,  at the expense of other desirable qualities, at least IMO, because that is what I always tried to do. 

Everything about bass smoothness and the need to decouple the woofer performance from the rest of the speaker system is mentioned directly and indirectly in Allison’s paper on room boundary effects. 

[Aadams]

After many hours of listening and some careful adjustment of the mid- range lpads, the 3a top of the AR31w configuration absolutely equals the AR9 in ambience, clarity and timbre.  They are also equal in imaging if the 3a is angled inward and the listening position is close enough so directly radiated sound predominates.   In my system the limit for imaging on the 3a is about 4ft before the image dissolves and the reflected sound from ceiling, floors and walls begins to take over.

The 3a, all the domed AR classics, require a lot fiddling to get the right balance for imaging but the reward is smooth, expansive sound that doesn’t make your hearing constantly search for the center of the image.  Very easy to listen to.  Only the AR domed classics (maybe the ADDs) and the LSi models will produce this far field effect in a such short listening distance.   

The AR9 holds its image to at least 10 feet after which both speaker systems sound identical.

The listening room is 13 x 29 with each pair of speakers set 5 feet apart along the short wall.  Speakers are positioned,  9/31        9/31   so the woofer pairs are not equidistant from corner intersections.  This asymmetrical arrangement, mentioned on the back label of every AR3a and in the AR9 manual, helps smooth the bass of both the 9 and 1w woofer so they are perceptibly identical on almost all recordings.   

It seems like a waste of a 3a to stack it as a woofer but the advantage of using identical speakers in this arrangement is the convenience of identical sensitivity when using identical amplifiers; there is zero effort in setting the correct gain to account for different speaker sensitivity.

Conclusion:  While stacking 3as, 58s, etc in this way yields excellent results I can’t say it is an inexpensive alternative to creating an AR9 equivalent.  It depends on your starting point and appetite for an AR9 level of sound.  IMO, at minimum, you should use identical amps and you will need a crossover capability and this assumes you have 2 pairs of 12 inch ARs.

Having no more combinations to examine I will end with a cursory ranking of the AR speakers tested in this configuration against the AR9.

The AR9 - reigns supreme because, given enough space, it will do everything any of the other systems will do, out of the box ,with little effort by the user.

The 581w  - It sounds like an AR9 and in the far field sounds like a 3a with zero effort except minor equalization

The 31w – Can image like an AR9 if used as a near field monitor and creates an exquisite direct/reflected sound at the point where the image dissolves.  The big qualifier is, none of this is true without a lot of setup effort and speaker system tune up.  But the payoff is great and that is why mine are now installed permanently next to the AR9s.  

Nihil Ultra

Adams

[Aadams]

The AR98ls has been resurrected in the form of an AR98T.  The “i” components have been added to the crossover and the woofer has been disconnected making it a 3 way system with 12db/octave roll off beginning at 200hz. The result is an AR98LSi/T meaning it is a top for a subwoofer.

I have temporarily pulled the 3a tops from the 31w and replaced them with the 98T to form an AR98T1w.  The 98t is totally passive in that its signal is full range into its crossover while the subwoofer is low passed at 200hz 24db/octave.  I thought some audible effect might occur with the mismatched slopes but have yet to detect anything that sounds like a problem.

I have listened for 3 hours to a variety of music and am confident the sound is good enough that I should take the time to compare them to the AR9s.  The 98 has no attenuators; all the AR9 attenuators are set to zero.  The signal path, source, pre-amp, equalizer, etc.  is identical except for the power amps.  

The two systems sound identical in the far field and different in the near field but I am not sure how to describe the nature of the difference at this time.  I will report  after more listening.

 

[Aadams]

I call this configuration an AR98T1w but, essentially, this is a comparison of the three upper drivers of the AR9 to the corresponding drivers of the AR9 LSi.  Both systems are indistinguishable in the far field, say 10 ft away.  Moving in from 10 ft, the difference becomes apparent and seems to be primarily related to speaker placement.  The LSi can be made to image close in like an AR9 with a clear image that makes you seek the center but, with a position change, it can also mimic an AR3a’s expansive sound stage in the nearfield.  If the 98 is toed in or set out further away from boundaries, it holds an image for some distance just like the AR9 but near the wall, as shown below, it generates an exquisite far field sound up close, just like a 3a but without having to fuss with tweeter and mid controls.  

I think the LSi series is more like the highest refinement of the AR classic domes than the next iteration of the original AR9.   The LSi sound is what I would expect from a perfectly balanced pair of 3as but somehow more delicate than either the AR9 or 3a, perhaps because of the point source effect of the tweeter/mid combo.

It is unfortunate the LS series was released without the “improvement”.  Now, after hearing the difference between the LS and LSi, it is no mystery, to me, why the AR9LS was not viewed by the public as a worthy successor to the AR9.  

In this speaker arrangement, against the wall, the difference is most noticeable in the near field playing large ensemble (classical) music.  The AR9 tends to present an orchestra in left and right halves, with not much in the middle, The LSi soundstage is broad, left and right are apparent but the center of the orchestra is integrated in the way it would be presented in the center rows of seats in an auditorium.  It is like the AR3a in the way one can raise or lower the volume as though changing audience seating from front to rear.  Again, this refers to orchestra and many live venue recordings listening within 4 to 7ft.  For studio recordings at this listening distance, the difference is not so apparent though, at times the LSi seems to have a more realistic mid-range, a quality I am not certain could be noticed if the speakers  were not side by side.

Things could change but, at this moment, I say the LSi trio of midrange and tweeter drivers produces the best sound I have heard from an AR speaker.

Aadams

[Aadams]

I find AR classic domes can image quite well but only in limited circumstances.  Below is a drawing of what I think I hear when listening to 3as set up in a way to permit imaging but also find the on-axis zone where the mix of sound is most enjoyable.   

If you want the classics to image they must be toed in with a “sweet spot ”vertex no further from the speakers than the closest reflective sidewall or floor.  If your ceilings are 8 ft you only have about 4ft in front of the speaker after which reflected sound will dominate.  If your ceilings are 10 feet you may have a tad more distance. If you have a side wall 3ft away then that is your limit.  Closer than 3ft to any reflector becomes pointless for imaging with a classic dome and probably an ADD series but 3ft is a bit close for listening even for me when using large speakers.

The room is all hard surfaces. The speaker mids and tweeters are set off the floor about 4ft from the nearest boundaries.

The diagram below shows what I think I am hearing.  To create the image sweet spot with a classic dome all drivers need to be balanced.  That is driver for driver between left and right should have near identical output which is not easy even when all the components have been refurbished.  Please forgive the crudity of the drawing I did not have the endurance to create it in extreme detail.

 

 

[Aadams]

The AR98T is now operating as a dual dome, 8 inch, 3-way-top for an AR58s woofer.  The sound sufficiently resembles that of the AR classic domes that I decided to replace the sketchy pots in my AR5s with Lpads to permit a fair comparison of the dual dome 10” AR5 with the dual dome  8 inch 98.

 Lpads, combined with rebuilt tweeters in the AR5, provide enough tweeter output at the 5khz crossover to compare favorably with the later version dome midranges that extend to 5500 and beyond.     

The AR5 and 98 pairs are sitting vertically, side by side.  

The signal path is identical up to the speaker switch.

Both speaker systems are crossed over below 200hz with bass being handled by a common subwoofer.

The AR 5 tweeters were set to max output. The mid-ranges were turned down to level match the 98 mids in the 2k band and then dialed in by ear using the lpads to achieve center balance.  The 98 8 inch and the AR5 10 inch LMRs were checked at 500hz for similarity of output and it turns out they are very close at the same gain setting.  In fact, the LSI modification appears to have made the AR98s less efficient than the AR5, with a practical effect of requiring zero gain changes to volume match the speakers, despite one being 8 ohm and the other 4 ohm.

Listening distance was 4 to 6 feet.  Speakers are set 4 and 6 feet apart toed in toward the listening position.

The result:

They sound practically identical, so close that sometimes on some music passages the switch could not be perceived.   It is easy to lose track of which speaker is operating unless standing at the switch box or next to a speaker but ultimately, after enough switching, it becomes apparent the 98 has a bit more refined sound and I am guessing it is because of the LS mid/tweeter unit.  

I am talking about a margin of difference so narrow it can only be noticed consistently if one is manning the controls or perhaps has a golden ear. The real achievement is an LSi can be matched by a Classic AR dome, if the classic has been sufficiently restored to its original state and carefully set up using Lpads to balance the output of driver pairs.

Edit:  The sound stage of the AR5s was too broad on many classical recordings, considering the listening position of only 6ft away, so I placed them on their side atop the AR98s.  Not only is the sound stage issue solved, the vertical alignment of the mid and tweeter seems to provide better clarity.  I had no complaints before, but it made a noticeable difference on some very familiar material. 

Disclosure: I can’t hear past 10k if that matters.  There certainly isn’t any actual music in that region.  

Aadams

[Aadams]

The AR classics with potentiometer or lpad attenuators, as opposed to later series with 0db attenuation settings, are difficult to balance.  If you want to hear a classic at it’s absolute best the attenuators must be adjusted to bring the corresponding drivers of the stereo pair into exact loudness balance.  In the case of the 3a and 5 the mid-range attenuator is the predominate factor in determining whether the sound is focused and centered as opposed to sounding vaguely centered and with a shifting soundstage.

I have found an easier way to balance attenuators that employs a 10 band equalizer.

For a 3a or 5 set the sliders to full minimum on every band except the 2k band which should be set to maximum.  This provides max emphasis at 2k which is in the middle of the mid range driver bandwidth. 

1. Assuming you already have the attenuators at a loudness setting that pleases you:

2. Play a mono recording with vocals, I like Glenn Miller or early Beatles for this, and listen within 3-4 feet to judge if the image is centered between the speakers.  Toe them in if you can.  Adjust the attenuators until the image is centered in the near field or at the listening position or both.  

3. Return the equalizer to its normal setting and reposition the speakers. You are done.

Adams

 

[ligs]

Adams, that is a nice solution for balancing the stereo speakers!

I have seen many people comparing speaker a with speaker b with all the level controls turned all the way up. This way none of the speaker is sounding at its best. 

In my DIY speaker building the midrange is the most difficult range to get it right. 

 

George

[Aadams]

On 12/15/2019 at 7:03 AM, ligs said:

Adams, that is a nice solution for balancing the stereo speakers!

I have seen many people comparing speaker a with speaker b with all the level controls turned all the way up. This way none of the speaker is sounding at its best. 

In my DIY speaker building the midrange is the most difficult range to get it right. 

 

George

Ligs

Hello,

For the last few years, I have wondered why the LST is always touted has having a better quality sound than an AR3a even though it uses identical drivers and crossover points.  The LST should be able to make more sound in bigger spaces than an optimally setup 3a but why would the same recording have a better sound quality?  I believe it is because the 4 LST mid range units are fixed at identical output and cannot be varied.

A stereo pair of LSTs, operating at factory tolerances, should be a matched pair in the mid range, always, without regard to how the spectral balance control is set.

I would further generalize and say that all AR dome midranges from the 3a through the 58s should sound identical when stripped of their faceplates, which means the Classic dome sound should sound virtually the same on axis, in the near field, to anything that followed that used the same family of mid domes.   

I must give @frankmarsi credit for dropping the LST clue over 2 years ago, in this thread, but at the time I had not traveled enough on this experimentation path to use the information.   I must also credit you, because I would not have bothered with lpads and mid range balancing had you not questioned my preference for the AR5 top over the 58s top, some time back.

 

Adams

[Aadams]

I have been comparing the AR9 to the AR3a for the last couple of days.  In this 4 way configuration it is easy to dial in a 3a to achieve the same spectral balance as an AR9 that is set to 0db attenuation.  As I listen I can find differences but one thing that is strikingly missing from the differences list is the fabled AR3a rolled off sound.  If you look at the chart below, which is based on a published AR chart supplied by Tom Tyson @tysontom, you can see the sloping integrated response curve of the 3a running below a superimposed AR9 response curve that is much flatter.    The chart seems to say the AR9 can easily produce high mid-range and tweeter sounds in areas where the 3a struggles.  The practical reality is this is not true.

For the AR3a to match the spectral balance of my AR9s the mid-range attenuator must be turned down near halfway with the tweeter at max.  The result will be same for any properly working 3a anytime the listening space includes walls, floors and ceilings because there is so much reflected energy.

I came to the AR world late and accepted that 3as had a “rolled off” sound but if they are refurbished with Lpads and a rebuilt tweeter or Hivi, they only sound “rolled off” if you make them so. 

I am guessing by the time digital recording arrived the classic tweeters were already degraded while appearing to work and the legend of the “rolled off” AR sound began.    The measured on axis response differences below set expectations for what you would hear in open space with no reflections, but what the you hear in normal listening space is surprisingly different and not rolled off at all.

[Aadams]

In an earlier post I said the AR9 was better than the AR3a because it could do everything a 3a could do, out of the box, with very little adjustment, given enough space.   After more time listening and comparing both systems, I need to qualify my statement because I realize there are capabilities of the 3a (any Classic dome system) that cannot be duplicated by the AR9.

I have been listening exclusively to a variety of live performance recordings that do a good job of capturing the space of the venue.  Both speaker pairs are sitting side by side with 5 feet between the pairs and 3 to 4 feet away from side walls.  The 9s are square against the baseboard. 

The AR3a can create a very convincing integrated sound field within 5ft of the listening position whereas the AR9 does not achieve the same quality sound field until 10 feet away. 

Another difference is, the AR3a has greater depth of field, keeping the same sound quality from 5 to 10 feet. The AR9 achieves the 3a sound field quality at the 10ft mark, after which it begins to deteriorate at the set power level.

The biggest difference is, because of the phenomenal dispersion, the AR3a allows the listener to choose listening positions within 5 to 10 feet, that vary the mix of direct and reflected sound, which is very helpful with live recordings.   Whereas, the AR9 sound is more focused and reflections that add space to the live recording do not develop until further back in the room and it does not develop perceptible progressive changes in the ratio of direct and reflected sound, at least not within my listening space.

My listening room is 30ft deep.  At 10 feet the AR9 sounds as good as the 3a.  Moving further back, the highs can be heard to fade and a “mid- rangy” quality predominates.  The way to fix this with a 9 is to turn up the power and the sound field will be deeper.  

An alternative for the AR9 is to toe in the speakers to get a better image closer in but this does not alter missing reflected sound and can affect bass performance.   

Finally, this is a mods and tweaks post.  The 3as I am using can be positioned without regard to bass performance, the tweeters are rebuilt originals and I have put in extra effort to balance the mid-range drivers.  Out of the box, a pair of AR9s is still superior to a casually set up pair of 3as but a standard 3a, mounted in a wall or bookcase per Roy Allison instructions and no bass equalization, could sound as good if everything is working properly and the mid range drivers are balanced for equal sound level.  The 9 seems to need larger spaces to sound its best.  A dialed in 3a can sound better than a 9 in smaller spaces where a 9 can be difficult.  

Adams

[Aadams]

My last 3a pair has been refurbished with Lpads and new (to me), in spec, Sprague Compulytics from a trusted source.  Now, with rebuilt tweeters this pair is as close to original sound as I can get and can be put into service with my other refurbished classic 3 ways.  It seems ironic, on reaching this state of refurbishment, that all of them are operating not as 3 ways but as elements of 4 way systems, because this project has made it clear that separating the low bass from the midrange driver benefits overall sound quality, especially in the critical, voice range.

The AR5, which, as a full range speaker, is arguably the most modern sounding of the classic dome systems, gets extended bass without effect on its excellent low-mid-range performance.

The AR3a benefits from having the low bass removed from the 12inch driver, which has such low distortion it works just fine as a low-mid-range unit.

The low bass can be optimized with room gain alone without sacrificing performance in the human voice range.

If you have the option to install any properly operating front facing AR 12 inch (Classic or ADD) , optimally, as specified by the designers, you can achieve maximum low distortion performance, but I don’t and this approach gives the same practical results.

[Aadams]

This is a 581W configuration with the 1w part hidden behind the milk crates.  I have done this before, side by side, with the AR9 to verify they sounded practically alike but I did not experiment with positioning.  The idea here is to get an AR9 sound without compromising the bass performance while gaining the flexibility to position the top unit in a way that best suits the listener.   It works.  The image shows the 58s on a baseline around 6 feet long with the listening position at the top of an equilateral triangle.  The best sound, for me, was achieved with the speakers angled inward 15 degrees from the baseline.   

An AR9, sitting square on the wall, in the same equilateral listening space, presents a clearly unrealistic soundstage on some orchestral recordings: the cure being to move further back to listen or toe-in the speakers, both of which are inconvenient.   

Adams

 

[Aadams]

Classic ARs were made for live acoustic recordings and are ideal for Big Band Jazz.  Classic era Big Band Jazz was always acoustic, frequently performed live, but rarely recorded well enough to be impressive today.  There are exceptions and I have found a good one; “Count Basie Live at the Crescendo 1958.” Remastered and released in 2016, this is the Basie “Atomic Band” at its zenith.  Many of these cuts were released over the following decades, peppered across single LPs, but this is the only complete set of the Crescendo sessions. All 91 recordings are performed before a live audience, mostly technically excellent and remastered to extract all the dynamic range which, at times, is a bit scary.   The level of ensemble performance is stunning. It is a steal at $14.99.

[Aadams]

I found another one.  This is an astounding restoration of The Duke Ellington Orchestra at Newport (COMPLETE) in 1956.  Released in 1999, it is the only complete recording of the entire live performance.  The original 1956 release was an abbreviated studio cut and paste job owing to a technical issue during performance.  This new version exists because some VOA tapes made at the the event for rebroadcast were not erased and reused before being archived in the Library of Congress.  If you like Big Band this a good one with the Ellington band at its artistic peak and the liveness is palpable on AR3as.

[Aadams]

Here is one from 1999.  Recorded live for TV at the Supper Club in NY, originally as reenactment of a 1930's dance club engagement, it was remastered as a CD recording and released in 2000.  Captures the live ambience and energy of an outstanding live performance.

[Aadams]

Jazz pay dirt from the 21st century.  For the of duration the pandemic only, Jazz At Lincoln Center is releasing, to the public, full length performances from its concert archives that are available on youtube.  The performance and production standards are top notch.  Video is at least 720 Hi def and sound is CD quality stereo.  Listener perspective is front row center.  If you like jazz quintets, septets and big band arrangements performed before a live audience, by top notch ensembles, this is a cost free opportunity.  Streaming live performance sound through Classic ARs is a real treat.  This a link to part of a 2 hour performance. https://www.youtube.com/watch?v=3SP3NfxI7dg featuring Coltlrane's Ole'.

[Aadams]

Released this week, full concert on the evolution of the American Big Band.  Concert performance and sound are top notch.

 

[Aadams]

An excellent presentation by the artist and sound engineer on capturing, editing and mixing acoustic instrument performance using modern recording technology. Focus is Jazz and Classical.

https://wyntonmarsalis.org/videos/view/editing-mixing-your-masterpiece-considerations-when-recording-jazz-jazz-congress-2020

[Aadams]

Here is another outstanding live performance that I stumbled across.

If you like Jazz, this is a link to a virtuosic performance by the Jazz artist Hiromi Uehara.  The video is of a concert in 2011 at Lugano Switzerland.  The picture and sound are excellent.  Her trio employs electric six string contrabass, rather than acoustic double bass which, combined with Hiromi’s use of the entire piano in her approach to jazz, means all the music notes from 32hz to 4200hz are present.  There are camera close ups that tell you when those low notes are happening as well has how low they are but Hiromi is the star.  Sounds great on large ARs. 

https://www.bing.com/videos/search?q=hiromi+at+lugano&docid=608048153906841450&mid=23AE497FFDE7E6BE16D823AE497FFDE7E6BE16D8&view=detail&FORM=VIRE

[Aadams]

The stereo sound stage of the AR9 begins to break down when the listening position nears 45 degrees off axis.  Modern orchestral recordings develop a “hole” in the center and the orchestra becomes perceivable as left and right halves. Live performance recordings of Jazz Orchestras, in which the configuration and placement of the musicians is known from video or photo, exhibit extreme displacement of the instrument sections, even from a front row center recording perspective.

My solution is to move the speakers closer together (4 ft) to get a 30 ish degree off axis listening angle at 6 to 8 ft, a setup in which everything comes together.

The AR3a + 1w hybrids were moved outside the AR9s, are now 6ft apart and do not suffer from the move except for one problem associated with solo grand piano recordings.   When a piano is recorded from the perspective of the performer, with low notes on the left and high notes on right, the piano will sound as wide as the speakers are separated and will be wrong if they are greater than 4 feet apart.  The result for me is, some pianos sound unrealistically large on the 3a whereas on the AR9 they do not.

[Aadams]

I thought the AR9 was not as good at presenting live performance recordings as the AR3a.  I was wrong.  It is just a good as an AR3a IF the Roy Allison Isosceles triangle rule for placement of any loudspeaker is followed.  These snips are from the Allison CD9 manual.

 

The problem with live performance recordings and speaker placement is when the speakers are too far apart the scale of the presentation can be overly large and not credible for a ”you are there” presentation.   Spacing that works for studio recordings can be wrong for live performance recordings.

 From the listening position, an AR9 pair too widely spaced will present a gap in center of an orchestral or live jazz performance recording where an AR3a will just make the sound stage bigger beyond credibility. 

After I moved my AR9s according to the Allison rule above, 5ft from side walls, (as pictured below) on a 4ft baseline, live performance recordings were presented as they should be. 

The 3as that were stacked on the 1ws now sounded a bit disadvantaged by comparison from the listening position, so I placed them in the bookshelf position atop the AR9s, as pictured.  With everything dialed in, volume and frequency equalized, the two systems sound identical from a listening position anywhere on the red centerline in the photo. 

In searching for audible differences, the AR9 cannot sustain a good soundstage more than around 40 degrees of axis. The 3a soundstage is so uniform and broad I can traverse the room with almost no change in presentation but when I do the same with the AR9s it's akin to walking across car headlight beams.

[Aadams]

This is the second pair of Classic ARs I have turned to the bookshelf position for which they were designed.  Both pair were turned sideways to address sound stage width but they also sound clearer.  With the first pair I accepted it was my imagination but with this second pair I am convinced the sound is better with the cabs turned sideways.

Also, if you like live performance jazz recordings that are both technically and musically excellent here is one from 2019.