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Aadams

BA/AR LST Hybrid (BLAST Stack) and AR5a, AR51w, AR358s

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3 hours ago, ligs said:

NHT 1259 has an in-line low pass passive crossover at around  100 Hz as in NHT 3.3.

The satellite is about 2 ft away from the backwall and  just sit on the boxes containing the sealed NHT 1259's.  

Does the JBL127h1 have a cut freq or is it allowed to roll off below a 100Hz?

Aadams

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I have a very rough idea about the frequency responses measured in my room with the help of  a Radioshack analog SPL meter and Stereophile test CD. The response cures will not be comparable to any other  lab measurements.  These curves are not calibrated and are meant to serve as a comparison purpose.  The microphone is placed about 1 meter between the JBL woofer and tweeter.

 

Keeping that in mind. It does appear that JBL 127H1 satellite without NTH 1259  begins to roll off  below 200 hz. This is due to the very small sealed box volume , a 50 ohm resistor across woofer and the placement of the satellite without room boundary reinforcement.  Combining with NHT 1259, the entire bass region (red and green lines) becomes flatter and extends at least to 32 Hz. As shown.

 

George

 

 

Satellite FR.PNG

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Most of this thread has been about the speakers atop the stack so this post is a twist that focuses on the AR58s sub-woofer.   As you an see in the photos the 58s are raised 1ft above the floor but are also inverted, with woofer on top, and placed square against the wall within 2 to 3 inches of the woofer frame.  Several position configurations were tried, following the Roy Allision research regarding woofer placement and this configuration yields the smoothest bass of all up to 200hz where the woofers are low passed.  Mid bass peaks are gone and perceivable room resonances at the listening position have vanished.  The curve for this position shows a rise, which is present, at the very lowest response range but I have yet to hear a recording where it is a problem. 

I also got lucky because the Allison study only predicts effects from first reflection from nearby surfaces and not additional walls as you would find in an actual listening room but it gives a good start.

image.png.6b74f649142062102fc314264ca1b1ae.png

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This post is about the AR1w but first I want to say something about the AR9.  The only AR9 I have ever heard is the original vertical.  The feature that always strikes me when listening is the bass output, but I don’t mean the depth or prominence. If the speakers are installed within the very liberal guidelines suggested by AR you are rewarded with automatic, practically flat bass to 200hz.  The beauty of flat bass is, voices seem to float above the low frequencies with zero coloration introduced by bass peaks.  I mention this because I now realize that any AR12 inch that employs a single front facing woofer is subject to coloration in the voice band because the woofer performance is almost always compromised in order to keep all the upper band drivers facing the listener.  This may not be true in a lab but given the usual limitations of home listening spaces it is a general fact.    

In the case of the AR3a the best position to achieve optimal and practically flat bass performance is to mount them flush in a wall or book case.   I can’t do this at my house.  

Thankfully, Roy Allison left a body of research that points to other ways of achieving practically flat bass response by using modern electronics and the AR1w.

I was recently reminded by one of our forum experts that inside every AR3a is an AR1w.  I purchased a long idle pair, restored them to life, disconnected the jumper and began testing them as alternatives to the AR58s as a passive subwoofer.

I have included images, below, of the left and right channels.  Using the 58s as stands places the 3a woofers 45” above the floor, almost equidistant between ceiling and floor.  I originally had them installed with baffles against the wall, but the room gain caused an annoying peak in the 50hz range when playing some pop music with three note bass lines.  The solution was what you see in photos and is a solution which I rejected when using the 58s woofers in the same position  directly one foot lower on the wall.   Room boundaries cause crazy phenomena with bass.

The 3as have been turned to correspond with the fig 7 below of the Roy Allison paper. 

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What I am experiencing now is almost like the voices floating over the bass that I hear with the AR9.  What I thought were clear vocals before are even clearer now.

The long term plan is for either the 58s for 3as to move to another room but while they are here I will have the tweeters rebuilt in these 3as, then biamp them alongside the AR5s with the 58s as bass units.  The intent is to determine if the voice performance of the 3a can be made to mimic the AR5 by splitting the high woofer octaves from the low octaves.

image.thumb.jpeg.ef4ad67e1f7718f11c76c74e28f27418.jpegimage.thumb.jpeg.b5635f1a809fe06da565667802d115ee.jpeg

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I couldn’t leave well enough alone.  As I listened to this new speaker arrangement I kept running across occasional rock and pop vocal recordings that had an annoying peak in the sub 125hz range.  I had been all over the gain controls and was convinced this was purely a question of positioning within this room.  I finally moved one woofer about 2ft along the wall and reversed it to face the opposite corner which reduced the low bass peak but it sounded too lean. In desperation I decided to return to flat settings on the equalizers and recalibrate everything by pulling out the headphones and refreshing my memory of how this music sounds with zero room reflections.   In the process I relearned what flat bass sounds like and this;  that most of the pop and rock vocal music that I listen to does not have very deep or prominent bass.  When set properly the bass almost never blurs the vocals nor is it so loud that the vocals are overwhelmedIn the end, all I needed was even milder equalizer adjustments to get very close to the headphone sound. 

I know this is subjective. If you like bass slam, listen to power chords and shredding guitars then you won’t be interested in what follows but, if you really want to hear all the words that are being sung, especially in classic rock and pop, then put on your headphones to adjust your system and get an easy improvement in both imaging and clarity.

You need merely decent headphones and these songs.

The original “Astral Weeks” by Van Morrison.  This is almost all acoustic with subtle textures easily obscured by mid bass peaks.  Morrison's vocals can be very difficult to understand on speakers but are completely intelligible on headphones.

Original “Won’t get fooled again” by The Who.  You can hear every word on headphones.  The bass line is surprisingly not prominent on headphones but, through 12” ARs, it is easy to have heavy mid bass that blurs the vocals

“Paradise by the dashboard lights”.  Every lyric word as well as the baseball base stealing metaphor can be heard clearly through headphones.  It is easy for the mid bass to obscure the male vocals in this one and blur the female voice.

Other tough ones are "Born to Run" with the E Street Band and "What would you say" by The Dave Matthews Band.

The change was so stark on some very familiar songs that I wasn’t sure I still had the low bass that I want when it exists in the recording.  To reassure myself, I played some classical recordings that I know have low bass and all is well.    

 If you can get your system to play these songs clearly then everything else will sound good.  Your perception of bass may change. 

    

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" In the process I relearned what flat bass sounds like.   In the end all I needed was even milder equalizer adjustments to get very close to the headphone sound.  What I learned was most of the pop and rock vocal music that I listen to does not have very deep or prominent bass.  When set properly the bass almost never blurs the vocals nor is it so loud that the vocals are overwhelmed .

Original “Won’t get fooled again” by The Who.  You can hear every word on headphones.  The bass line is surprisingly not prominent on headphones but through 12” ARs it is easy to have heavy mid bass that blurs the vocals"

Well said! Here is an in-room  frequency response of NHT 3.3 . Some people describes it sounds like a pair of headphones and it has excellent vocal clarity. The vocals from 100 hz and up come from the front drivers while the bass from the side mounted 12" woofer(also know as NHT 1259). My interests in 92 db satellite speaker and passive stereo subwoofers with 100 hz crossover were inspired by NHT 3.3. 690945784_NHT3_3FR.thumb.PNG.cba1f56cd8caeab8ecf348ce718a1f13.PNG

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Ligs

Thanks,

It is a journey with no definitive answer.  What would you say if you were a doggie on chain?

Chumps like us,  maybe we were born to run.

Adams

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I used to be a research scientist so I am used to pursue a goal for a long time with occasional breakthroughs. As long as we are learning something new and still having fun then we ought to keep going. 

 

George

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This is a comparison of a refurbished AR3a vs AR5.  It is a mod and tweak topic because both speaker systems are bi-amped with a common bass system provided by an AR58 crossed over at 200hz. 

image.thumb.jpeg.6e80ac139be611e31d7016c4985b9db1.jpeg

Except for impedance both systems have identical dome mids and are crossed over from mid to woofer at around 500hz  for the 3a and 600hz for the AR5.

The AR5 has original Compulytics while the AR3a has all new NPEs in place of the original ICC wax caps.

Both speaker models have rebuilt Chris tweeters.

All speakers still have potentiometers,

For this comparison:

Tweeter and mid controls were set very close to identical.

Electronics and sources were identical

Both systems were sitting adjacent at a listening distance that varied between 5 and 7 feet and volume matched within 2 seconds after the switch.

There were two listeners.

You ask, “What is he up to now?”   Answer:  To find out if an AR3a can be made to mimic the sound of an AR5 on human voices. 

Result:

Short version: An AR3a can sound virtually identical to an AR5 in rendering human voice, which is contrary to many opinions expressed over many years on the CSP.  You can Google it.  

Long version: I was among those who thought the 3a was weak at presenting human voice.  My impressions were gained through direct comparisons between my totally original 3as and AR9s when playing pop/rock vocals that are difficult to understand.  (Examples below).  Additionally, the 3a seemed to always have a “dark” quality that made voices of Gordon Lightfoot, for example, and Allison Kraus a bit husky and veiled.   The only person on the CSP, to my knowledge, who insisted the 3a was as good as the AR5 at voice was Tom Tyson but even he specified the special conditions where he knew this was true or otherwise there could be problems from reflections or interference.  Edit: I finally found the quote:

On 4/28/2018 at 12:04 AM, tysontom said:

It also occurs to me that if you are mounting your AR-3a on a stand or table (above the floor but back against the front wall), your AR-3a will be susceptible to the "Allison Effect," a boundary-caused dip of several dB as the reflection from the wall behind the speaker (and the floor) interact with the direct output of the woofer and cancel (null) certain frequencies to some degree, usually around 300 Hz or so.  This could impact intelligibility at those frequencies, of course, and the way to fix this problem is to mount the AR-3a flush with the wall or in a bookcase flush with books around the speaker so that the woofer sees a true 180 solid angle.  It's not always easy to do it that way!

With the AR9, the idea was to get the woofers to operate close to the floor-wall boundary to get maximum reinforcement and minimum boundary dip, such as the wall and floor, and to limit the pass band of the woofers for smoothest response.  Therefore, with side-mounted 12-inch woofers operating up to 200 Hz, there had to be a lower midrange driver (requiring a 4-way configuration) to handle the mid-bass frequencies.  This also allowed a higher crossover into the 1½-inch midrange dome to improve its power-handling capability, and so forth in the design of the AR9.  It was definitely a step forward in design.

The AR-3a has been criticized in the past for its somewhat "heavy" sound, and some of that problem was due to a crossover issue during the changeover from the Alnico woofer to the newer ferrite woofer in the 1969-1970 time frame.  Also, the relative balance of the midrange output to that of the woofer seems to give a slight sense of heaviness, but it is very minor. 

 

What I have discovered at my house is the AR3a is easily the match of an AR5 in vocal rendition if you do these things

1.Remove bass peaks below 200hz.  Not easy to do with a 3a unless you mount it flush in a wall or book case.  The last octave of bass must be flat or rolled off as perceived at the listening position. This is not a problem with the 5 because it does not naturally yield much of the last octave unless forced.  If you place either speaker in a position to emphasize the lowest frequencies using room gain you will probably introduce peaks that interfere with the perception of voice, but the effect is much worse with a 12 inch woofer.  My solution was to make both systems use the same bass sub-system which I have already optimized for this listening area.  The 3a woofer is rolled off 24db octave below 200hz.

2.   Tweeters aren’t required to render a clear voice but once the bass is worked out voices will sound dull without tweeters that work well.  For either of these systems that means rebuilt or HiVi.  Even if they pass the paper roll tube test, I promise you, your UNrefurbished, 50 year old, ¾” AR domes are defective. 

3. Asking a speaker to render Louis Armstrong, Ella Fitzgerald, Sarah Vaughn etc. is not a challenge.  The mixes were set up to make the voice the prominent feature.  A real challenge is to play some of the following and understand the vocals.

- Elton John “Goodbye Yellow Brick Road”

- Elton John “Saturday Night is Alright for Fighting”

- The Who “Won’t Get Fooled Again”

- Dave Matthews - “What Would You Say”

- Bruce Springsteen and the E Street Band “Born to Run”

- Bruce Springsteen and the E Street Band “Rosalita”

- Gordon Lightfoot “The Summer Side of Life”

-Van Morrison – “Astral Weeks”

-Cowboy Junkies- "New Dawn Coming"

All these songs have lyrics that are clearly understandable on well sorted systems.  You don’t have to like the music but if you can’t hear the words in these songs on your speakers you are missing a lot of musical detail in the recordings you do like.   In my comparison the 3a easily matched the vocals in both timbre and clarity to level of the AR5.

By-products of doing this comparison: Imaging

Bass interferes with imaging.  Remove the bass as a problem and imaging blooms.   The 3a and the 5 were conceived in the days before imaging was a feature but don’t believe it if someone tells you they can’t image.  They can be amazing.

Adams

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The AR5a is no more.  The AR58s subwoofer has been replaced by an unjumpered AR3a making the new system an AR-51W. In the subwoofer role, there was no perceivable qualitative difference so the combos were chosen based on wood grain. 

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The 58s is now mated to another 3a to become an AR-358, to be operational after a tweeter rebuild.  This one will be used to compare the sound to an AR9.  This is NOT about winners and losers but differences. 

image.png.da8609efa9a0e773ee0a460c9ba2380d.png

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This post is about a tweak that will work for any Classic AR with pots and not about the mod configurations that dominate this thread. 

I forgot to mention one big impediment, IMO, to making a properly working AR3a or AR5 produce a good image.  The tweeter and especially the mid output must be virtually identical across the stereo pair.  There is so much variation in pots that you cannot do this visually, it must be done by ear and it is not easy with one person doing everything.  I only noticed this recently when I made a change in the Satstack that produced a discernible leap in its imaging and which materially separated it from the AR5.  The Stack was suddenly razor sharp by comparison and I was not happy that the 5s were a little off balance.    The solution was to adjust the mid controls until the drivers produced the same output level.  Until recently I thought “close” was good enough but it is necessary, for imaging purposes, to dial them in exactly.   I am speculating here but I suspect the dome mid control variation may be a big reason why the 2ax has a better imaging rep than the classic domes.  The first 5.5 octaves of music are covered by the 2ax woofer whereas the domed systems barely cover 4 octaves in the woofer before crossing to the mid which may or may not be set correctly according to pot condition and listener care. 

Conclusion: Classic dome ARs are fit to excel at imaging but they require more attention because of pots or even Lpads.

Status update: The AR 358s is still in the pipe awaiting tweeters, which are inbound.

Adams

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More Classic model tweak info:

The challenge for the 3a in this AR358 configuration, when compared to an AR9, will not be bass output but the imaging capability.  While it is fact, a properly functioning AR9 can play practically flat for almost 10 octaves, it is also fact that the boundaries of most music occur will within the range of a properly working 3a.  The AR9 was designed to be accommodating in a variety home listening environments.  It was and is, by comparison to most full range speakers, automatically flat and ready, out of the box, to provide an optimum full range stereo image with very little fiddling and futzing around if installed within simple and practicable guidelines.  The AR9 appears to be AR’s first great imaging loudspeaker.  Now days legend says the Classic and ADD domes could not image well and were weak, in near field listening comparisons to more modern speakers, and for this reason AR moved on with a tour de force system that still impresses.

Legend is wrong.    

In working with my AR5s and 3as I have discovered these old speakers can image very well in the near field if they are adequately restored to have proper output on all drivers and the rear gain controls have sufficiently fine granular adjustment to allow exact balance between left/right mid to mid and tweeter to tweeter.  The pots are functionally another set of balance controls that must be accounted for to achieve good imaging with the Classic ARs.

Below is an easier, one person method to balance a classic pair of ARs for imaging, assuming your speakers are in phase and your preamp balance control is working correctly.

1 Play a mono recording of a featured vocal performance or if stereo , engage your mono switch.

2 Set the amplifier balance control to full left or right.

3. On the active channel set the tweeter control to max and the midrange where it sounds right to you

4. Switch to the other channel and set the controls where they seem to match the settings you just made on the first channel.

5. Set the balance control to center and at the listening position listen for the phantom center channel. If the sound is centered, switch to stereo mode and listen. It most likely won’t be centered so, switch back to mono and go to Step 6

6.   Use the mid-range balance controls to pull the sound either left or right.  This may seem obvious but to be clear, if the sound is center left, for instance, you have two choices; lower the gain on the left speaker mid to PUSH the balance to the right OR raise the gain on the right speaker mid  to PULL the balance to the right.  This works.  When the sound is centered Turn ON stereo mode and check for centered image. 

It would be a lot easier if there were no controls, as later happened, but these variable controls were a great idea before equalizers.  For imaging they are a nuisance but the imaging capabilities of classics are real and they can be astonishing with their very wide dispersion.

When I get the amps, moved the “AR9 imaging challenge” will commence.

Adams

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On 4/28/2019 at 12:17 AM, Aadams said:

This may seem obvious but to be clear, if the sound is center left, for instance, you have two choices; lower the gain on the left speaker mid to PUSH the balance to the right OR raise the gain on the right speaker mid  to PULL the balance to the right.  This works.  When the sound is centered Turn ON stereo mode and check for centered image. 

The question has arisen, “Why not just turn the main balance control until the image is centered?”

 

Answer:  In the early 12 inch ARs, large, fundamental chunks of midrange frequencies are directed through the woofer.  There is no woofer pot so the main balance control is the only means to balance the woofers.  By balancing the tweeters and especially the mids you are aligning their output with the woofers so the midrange image is not skewed at the speaker box.

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First, I must say I did not see this coming.  I have been procrastinating on putting the amps in place for my AR358/AR9 imaging comparison when I got the opportunity to compare an AR51W to an AR981W.  I have spent most of the day comparing the two systems.  The 98 is a bit more sensitive than the 5 but once I found the volume equalization point it is impossible to consistently guess which system you are listening to in this configuration.   I am doing the switching and even I lost track at times.  The sound field produced by either speaker is so similar at five to seven feet they are indistinguishable, except in direct AB comparison, which leads to this conclusion: The 98 upper range driver combination is formidable.  I don’t think I have heard such clarity from another AR speaker.  The only thing I have that is comparable is my SatStack but the little 4” drivers get messy when crossed over at 100hz as these speakers were today.

I listened to the AR98 briefly in a standalone config away from the wall and off the floor and it sounded thin, as expected.   I connected the 98 to the biamp system and changed the crossover from 200hz to 100hz, a point that is tolerable for the 98, to share the same bass subsystem as the AR5.  The last octave and a half of bass was eliminated as a point of comparison. 

Impressions

Imaging

Both systems image well.  On orchestral recordings The AR5 sounds a bit more expansive where the 98 is more concise.  On studio mixes the 98s had apparently clearer vocals but the instrument and performer placement were the same IMO. 

Timbre

So close it doesn’t matter but the mid-range seems a bit more assertive in the 98 and cymbals seem too forward on some recordings but this is just my opinion.   I could have fiddled with the equalizer to bring the 98 to the 5 but it would not have the changed the difference in clarity between the two.  Had I done the reverse and equalized the 5 to the 98 it would not have changed the clarity difference and I might have lost a tweeter.  The timbre may have played a role in the perception of clarity.  At one point I turned the 5 mids to full output, which didn’t affect the difference in clarity but then I had to rebalance the 5s, an inconvenience of the classic ARs, at least for imaging.

Too bad AR didn’t make this driver combination in an 8 inch 3 way, it would make a perfect top for a subwoofer.

image.png.05cf9e3ab1d82ed54005f9d65a9a91f3.png

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I spent most of this afternoon comparing the 981w to the Satstack.  Eventually, I was able to get the two systems volume and image equalized from the listening position.  Why would I bother? The answer: The more I listened, I increasingly felt that the AR98LS runs a little too hot in the mid-range and I thought I could use the Satstack (Boston CR65s), which are not shy speakers, to help verify what I thought I was hearing.

The bass crossover was raised to 150hz, a setting that seems to work well with the 98 and puts the CR65s back in their comfort zone.  The short version is, I discovered, in the octave centered at 4k, the AR98ls needs taming to bring it into line with the CR65s.    

I don’t think this is news.  I have read in CSP where the LSi version of the 98 fixed some irritating sonic aspect of the LS and that the mod can be applied to bring the LS to the LSi spec but I will use an equalizer.  

The bottom line:  A hot midrange in the 4k range skews voice timbre and explains why cymbals and gated snare are so prominent on a 98ls.  Still it can image very well and clarity is superb.  

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"The bottom line:  A hot midrange in the 4k range skews voice timbre and explains why cymbals and gated snare are so prominent on a 98ls.  Still it can image very well and clarity is superb."

Let us assume both AR 98LS and CR65 have the same axial response around  4K hz, AR 98LS  would sound louder just because the wide dispersion characteristics of the 1.5" dome midrange. I think our ears receive directional clues from the first arrival sound but our perception of loudness is from the total acoustic energy(power response) from all directions. Many audiophiles prefer an overall frequency response for a speaker which is sloping very slightly down from bass to mid to high range. 

 

In addition, our ears are most sensitive in the midrange. Proper voicing the midrange, hence , is critical for naturalness and musical enjoyment. 

 

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59 minutes ago, ligs said:

Let us assume both AR 98LS and CR65 have the same axial response around  4K hz, AR 98LS  would sound louder just because the wide dispersion characteristics of the 1.5" dome midrange.

Ligs, good to see you back. 

You may be right about the energy.  It takes three CR65s stacked just right to get the same expansive sound of one AR3a with the mid turned down about a 1/4 turn.   Excluding the 58s and 915,  which were "value" speakers,  the LS series was the first , I think, in which AR used a mid dome wide open with no damping material, attenuation circuit or mechanical focusing.  As with previous domed mids, this one probably measured flat in the test environment but in reflective surroundings needed toning down but I am just speculating.   My AR9 mids with their concave horn covers and acoustic blanket are set wide open and I don't hear this brightness problem but an AR3a mid wide open in the same environment can be quite annoying and must be turned down. 

I have been running with grills off awaiting new material.  The grills originally had a foam inner surround that may have subdued the reflected energy.  When I recover the grills I will replace the rotted foam material on the inside edges and we shall see if there is a difference.  I would prefer not to use the the equalizer.

Adams

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Ligs I believe you were correct.

I finished repairing the 98ls grills today and re-installed sound absorbing material around the inside edge to replace the original foam that had rotted.  I put the grills in place and discovered that the grills of the AR98ls are an integral part of the speaker system.   They were instantly transformed into what I had expected them to be from the outset. 

I lowered the bass crossover to 100hz and compared them to the AR5s that I like so much.  It is now very easy to dial them into the AR5s using only volume controls and with zero equalizer adjustments.  When grills are off, I must lower the entire band between 500hz to 5000hz two to three decibels to get them where I want which is like turning down the mid control on an AR3a, practically the same adjustment over the same band of frequencies.  They also are bit more focused, akin to an AR9 but they also sound  expansive, similar to an AR Classic dome but without the muss and fuss of attenuators.

The material with which I lined the grills is ½ inch polystyrene pipe insulation.  I don’t know how it compares in performance to the original foam, but it works for my needs, is readily available and easily fits in the space with double sided tape.

The 1985 Audio review of the 98ls was performed with grills off.  The reviewer must have had a very dead listening space or ears of steel or didn’t care.  The review sounds perfunctory anyway, like he was making a deadline but he did give it good marks for imaging and I agree.  The big leap here is a single front facing 12" with the mid range neutrality of a properly setup, flush mounted 3a or an AR5, but with a bit more clarity and lot more power handling.

So here is another free tweak that has nothing to do with mods.  If you own an LS series and you are missing the interior grill surround foam then you are probably not hearing the speakers in the way they were intended.

I will be moving these 98s into the room with the AR9s to compare imaging. Combined with the AR58s for bass they will become AR9858s but I still haven’t moved the amps.

Aadams

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On 5/11/2019 at 7:12 AM, ligs said:

am glad you can contour the sound of speakers to your liking with simple adjustments.

Ligs

I was a bit hasty when I said the grills solved the problem.  My premature conclusion was based on listening almost exclusively to vocal recordings, when I should have included a good selection of orchestral.  Over the last two days I have been listening exclusively to orchestral music and eventually realized French Horns were sounding more like trombones, Trumpets sounded like Piccolo Trumpets and Violins had way too much sheen on the high strings when heard through the 98s.  Nothing offensive to the ears but it just wasn’t right.

Bottom line is, even with the grills and absorbent foam, I must lower the entire 500 to 7k band about 2db to bring the 98 into line with the 3a, 5 and the CR65 stack.  Other than that, my previous opinion is unchanged.  It is an excellent imaging speaker with an expansive sound but not at the AR Classic level of expansiveness.

 This equalizer issue makes it much more inconvenient for me to directly compare the 98 to the AR9.

I wish AR had given the 98ls more attention before they released it into the wild. 

Aadams

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Problem solved. 

The AR98ls now has the sound profile of an AR5 without using an equalizer.  Eventually, I identified the problem of over-brightness as being totally in the dual dome mid/tweet unit and not the entire 500-7k band but more like 1500 – 7k. 

 My solution was revolutionary and there was lot of trial and error but in the end, I settled on using one layer of felt cloth and three layers of muslin placed in the top 7 inches of the grill which covers both domes but not the 8 inch LMR driver.  The 98ls is now, to my ears, a very enjoyable speaker.  It still has an expansive quality and its clarity and imaging are better than the 5 but not worlds better. The difference is only obvious at the moment of the AB switch and afterward for as long as you can remember which speaker was last switched.  Once you refocus on the music it is easy to lose track of which speaker is operating.  

This AR98ls is the only AR 4way I have heard with a single front facing 12” woofer.  It has a 200hz crossover at the woofer which, with its 4 way configuration, gets the bass out of the mid-range but to get the smoothest bass it is designed to be placed on the floor, its back squarely against a wall or flush mounted in a wall or bookshelf, vertical or horizontal.   Floor placement puts the tweeters and mids between 16 to 29 inches off the floor, which seems low to me and is at odds with the AR recommendation to place the tweeters at ear height for listening.   There is a shelf/floor switch near the input terminals, but it has nothing to do with bass frequencies.

As a passive subwoofer only, the 98ls is not very useful.  The 200hz crossover is an impediment because an active crossover point should be at least an octave away from a passive crossover point to limit interference effects, which I have discovered can be audible.  For the 98ls the active crossover should be 100hz or below.  This means any AR 12inch 3 way from an AR3 through the LSi series would be a better choice for duty as a passive subwoofer because, in those units, the entire bass frequency band, up to the lower mid-range, is available for a crossover choice.

The best use for the 98ls IMO, is as a full range speaker, if you can deal with its placement requirements or as a top for a good subwoofer which would give the 98ls greater freedom of placement in the room.

It could also be used as a bottom for a good modern two-way speaker crossed over at 400hz but this doesn’t relieve the placement constraints of the front firing woofer and mid.

I am still working toward a comparison of the 98ls to the AR9 but have not decided if the 98 will be full range or a bi-amped top.

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The AR98LS has been modified to achieve its highest purpose at my house.  It is now a passive subwoofer, which means the internal crossover has been bypassed and the woofer directly wired to the amplifier with the active crossover set at 200hz in this case. 

The  woofer sits very low in the 98LS cabinet which was intended to be placed on the floor and against the wall,  but I turned it sideways so the baffle is perpendicular to both reflective surfaces.   The bass is very smooth.  No peaks or dips that I can detect by ear from the listening position.

The 98ls system required too much effort to fit into my scheme of things.  Without an equalizer it is not a great sounding speaker, in fact it is harsh. With an equalizer, the adjustments that must be made aren’t of the minor fine-tuning category but gross adjustments in bands that are just not normal for a linear speaker.  

The modification I performed is completely and easily reversable.  No harm was done to the original speaker system save one tiny hole that can be made to vanish with little effort. 

The AR1w pair has been re-jumpered to an AR3a which now sits next to the AR5 and Satstack. 

Now, with the 98Ls off the menu, I am back on the original plan regarding the AR9 and 358 which can also be flipped into a 581w.

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"The AR98LS has been modified to achieve its highest purpose at my house.  It is now a passive subwoofer, which means the internal crossover has been bypassed and the woofer directly wired to the amplifier with the active crossover set at 200hz in this case. 

The  woofer sits very low in the 98LS cabinet which was intended to be placed on the floor and against the wall,  but I turned it sideways so the baffle is perpendicular to both reflective surfaces.   The bass is very smooth.  No peaks or dips that I can detect by ear from the listening position."

Did you notice any difference in the bass quality of the AR woofer driven through the crossover vs driven directly by the amplifier?  Without the resistance(perhaps as high as 0.8 ohm) from the crossover inductor, the AR woofer may sound more controlled and more extended  in the bass. 

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2 hours ago, ligs said:

id you notice any difference in the bass quality of the AR woofer driven through the crossover vs driven directly by the amplifier?  Without the resistance(perhaps as high as 0.8 ohm) from the crossover inductor, the AR woofer may sound more controlled and more extended  in the bass.  

Ligs

I don’t know for sure because the placement of the 98 when running through the crossover was always baffle toward the listener and above 100hz.   After the mod I placed it in exactly the same spot where the 1w sat but woofer on the floor as described.  The bass gain remained exactly where the 1w gain was set.

My initial subjective perception is, after playing Flight of The Cosmic Hippo and a good sampling of other music, the bass is not quite as strong at the low extreme as the 1w but the 98 bass is overall smoother.  When the 1w was in the same position, woofer down but 1 ft above the floor, it set off objectionable room modes at the listening position and thus always sat inverted and was raised as shown below which was quite satisfactory.  I have never installed a 3a/1w cab directly on the floor.

Adams

image.png.628008f23f91b1dcbb16ed26d8d6b309.png 

 

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Today I setup the AR58s pair in the bi amp configuration as tops for the AR98ls subwoofer and compared them all afternoon with the AR5s.

 I got my 58s about 4 years ago after reading in the CSP that it was perhaps the ultimate evolution of an AR bookshelf speaker.  My infatuation subsided, when I realized the AR58s is hard to live with unless you are willing to use an equalizer to tame the mid-range driver to compensate for its lack of an attenuator switch.  The ads described the 58s as a “value” system for those wanting top line AR sound for a low purchase price.  It was in fact an AR91 in a plain wood case with no attenuators and no acoustic blanket and was probably a means to clear from inventory the last of the tweeters and mids that were used in the vertical series.  Used with an equalizer it works well.

Another issue for me is the front facing 12” woofer that is crossed over at 700hz, mixing low bass with the lower mid-range in the same driver, which,  IMO,  muddies human voice and is in fact the opposite direction AR took with all of its TOTL  12” systems.   

In the bi amp configuration, the 58s woofer works as a large LMR driver between 200 and 700hz, the whole system effectively working as a big satellite for a subwoofer. 

The AR5 and 58s were on a switch connected to identical electronics and source.  The bass below 200hz for both systems was identical.  The systems were sitting adjacent, about 3ft above the floor, at least 6 inches from a rear wall and no other boundaries closer than 4ft.

I guess I was hoping for a miracle, but it didn’t happen.  The mid is still too bright by about 3db but using the equalizer allowed me to dial it in to be pleasant sounding and make it very difficult to distinguish from the AR5, with very good imaging, though not expansive like the 5 or the 3a.   The 58s can be an excellent top for a subwoofer but, like the 98ls, doesn’t fit into my scheme of things so it will go back to subwoofer duty. I don’t mind adjusting gain when switching but having to remember equalizer settings from speaker to speaker is too much. 

On a positive note, the 12” woofer works very well as an LMR up to 700hz, if it doesn’t double as a subwoofer.  Male and female vocals were very clear and sounded virtually identical to the AR5, once the midrange driver was turned down via the equalizer.  

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