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

[Aadams]

This topic was spawned from the AR forum discussion of Dome Mids vs Cones.  It seemed with all of the good full range 2way speakers available it should be possible to add a subwoofer and create a great sounding modern system comparable to a large AR for not much money.

 

 

 I originally placed this thread in the BA section because small BA speakers have a great reputation and are plentiful. There are hundreds of pairs of BA 2 ways for sale on the used market any time you choose to look.  I eventually settled on BA CR65s as the tops.

Objective: 

Create a system that will substantially duplicate the full range stereo sound of a Classic or ADD AR 12 inch speaker.   

Assumptions: 

Equalizer will be used  

Dual Subwoofers  - one for each channel 

Mirrored pairs of two way bookshelf speakers positioned such that they produce a uniform soundfield covering at least a 90 degree angle per stereo channel.   Mirrored triplets would be ok if it really can't be done with pairs. 

Sufficient, quality watts will be available.  

Question: 

 

This thread topic originated in a post I made in the BA forum.  I have chosen to continue it in the mods and tweaks forum for the following reasons:

1.        The original idea was a failure because of several issues which all stemmed from two main problems,

a.       Subwoofer performance vs Cost               

b.       The difficulty of integrating the Subs with satellites yielding musicality equal to an AR12” 3 way speaker.

 

2.        On a whim. I decided to salvage what was left and see what would happen if I used an AR58s as the bass module for each side.

 

3.       IMO this topic is now about something other than AR or BA speakers alone.

 

 

If you can imagine two AR3ts angled and sitting atop an AR3 then you can visualize a 12” LST2, which BTW never existed for sale.  As I write this, I am listening to a similar configuration , only in this case I am using BA CR65s atop a AR58s pair.   My original target with subs and satellites was to duplicate the 58s sound but, as I said, that was failure.  What I am hearing now, and for the last five days, is easily equivalent to AR9s except in the very deepest base i.e. 32hz range.  Edit: In retrospect, this last statement is early hyperbole from 2 years ago.  This approach does produce AR9 level sound but is not easily reproducible until the April 7, 2018 post below. 

I don’t see why this can’t be done with any AR12”  woofer system and two amps that can each carry a four ohm load.  I already had the amps and 1 equalizer.  The additional total cost for used equipment was about $150 which purchased 4 BA CR65s and an equalizer.  

Taking the system to the LST level will require an amp that can carry a 2 ohm load and another pair of BA speakers.  I have been listening and comparing this arrangement to 9s and 3as all week using high dynamic, full range classical recordings and demanding non-classical.  It does take some dialing in but it really works.  Fearing I would come off sounding like just another hi fi nut I almost did not post but this is so doable at a bargain price I decided to share.

I have received advice and tips from a few members on this forum that lead me to this but I did not drop your names in case you prefer to remain unconnected with this mess.    

Aadams

[genek]

How are you wiring these together? Series, parallel, some combination of both?

[Aadams]

4 hours ago, genek said:

How are you wiring these together? Series, parallel, some combination of both?

The BAs are wired in parallel. The 58s were already in place on a separate system.

 

[frankmarsi]

I appreciate the effort and with all respects but, I don't buy it!

Reminds me of when I was a kid haunting the streets of "Flatbush, Brooklyn" and "Staten Island" in the years 1957 to 1967 always looking for speakers from TV's and record players in the trash.  In fact 7 years ago, I found a pair of water stained EPI V100's.

I was always hoping and scheming to find something to cobble together to sound even remotely like the stuff I saw in magazines and newspapers. My only concern was to find a speaker that would be the biggest and best than I ever found before..

Although your creation may distantly resemble a Wilson TOTL monster-speaker, I doubt it'll ever come close to it.

Oh, and the AR-LST comparison; I doubt your monster will ever come close to dual LST's driven by dual high-power amplifiers!

In parting, again I feel that your efforts are a near noble attempt, especially in this day and age but, I still don't buy it.

And, I'm not even an expert, I'm just an individual that's been playing with speakers and amps for over fifty+ years.

FM

 

[Aadams]

On 7/12/2017 at 7:26 PM, frankmarsi said:

I appreciate the effort and with all respects, but, I don't buy it!

I don't know what a Wilson TOTL Monster is but I will take it as a compliment.  With regard to the LSTs, there is no way two of these Hybrids will equal the air moving ability of stacked LSTs but it could match the ability of an LST pair given the same room volume.  Each hybrid stack has 9 drivers biamped.  The  BAs,which carry most of the musical, load are driven by a 500l watt/ch Crown.  The 58s, which really only carry the bass, have 100 watts per side and the room is small . 

I don't know if you have read all of the posts in this thread as well as the ones that originated in the BA section but I understand your skepticism.  We are about the same age and have been in this hobby for about the same time but this is not new. What I have done has been done before. It is not ground breaking in execution certainly. This is nothing more than an AR3 with a stack of AR3ts on top.  It is in fact something similar to stacked LSTs with 16 blown tweeters and Jantzen electrostatics on top.  All I have done is used two equalizers as outboard crossovers to create a transition point between two already proven and well regarded speaker systems. The groundbreaking part, if any,  is the equipment to do this is now for sale dirt cheap waiting for someone to seize the opportunity. Before I powered up the third BA speaker my incremental investment was equivalent to $50 in 1975.  You couldn't buy an equalizer for that price back then let alone 6 high performance wide range miniature two ways with drivers way more rugged than the comparatively dainty AR Domes in the AR3t or LST.  When I wired the 3rd BA, I needed a more capable amp so I spent another 1975 equivalent $50.   I now have a total of $100 additional 1975 dollars expended to build out this system with equipment that couldn't be purchased for any amount of money back in 1975.  And If I had spent thousands of dollars to accomplish the same thing it would not be newsworthy.  The news is, the price to upgrade from AR 58s sound to something much better is negligible.

 I am not going to spend time on credentials but I do know how live music from large string and wind ensembles is supposed to sound and I know that occasionally a recording played on a full range system, with some listener imagination, can be pretty convincing.  When I say this Hybrid Monster sounds better in some ways than an AR9,  I know it is true because the two systems are sitting very close to each other in my house fed simultaneously by the same program source.  The smooth effortless extended bass of the AR 9 is not challenged by any single driver AR 12 inch but the full range of an orchestra can be convincingly represented on any competent system given a good balance of scale and proportion between the room and a music system with full range capability.   

All I can say is, it works and in the beginning I was as shocked as you are 

Lastly, I am honored that a thread I initiated attracted the attention of your acerbic wit.  It is always good to have the opinion of an expert. 

[frankmarsi]

Hi Aadams,  I guess the only true opinion I could have would be if I actually heard your system to make my own determinations first hand.

I'm presently struggling with the idea of stacking another set of LSTs on top of my set of four.

A year ago I purchased another amp to match what I already have driving my four speakers but, lifting the additional set of speakers over six feet to place them on top of the existing set that sits on two foot stands is causing the delay. Thirty or 40 years ago I would've not hesitated but, these days doubt has set in. Other than that, I question if such a set-up is actually worth the attempt.

My set-up sounds very big as it is, do I really want more? Oh, please I'm a hog for big-sound though, I must temper my fantasies with reason.

On another note, I'm a dedicated fan of the AR mid-range speaker as much I am of the AR-3a 12" woofer causing me to wonder if the sound quality you're speaking of with your stacking dissimilar brand speakers is of good quality. In any event I think that you're having fun doing what you're doing so, ultimately it's appreciated.

FM

[AR surround]

Aadams,

Did angling the Boston A40's away from each other eliminate any problems with comb filtering?  (Is this the same as lobing?)  I ask because once I had what turned out to be a not such a good idea.   I made a larger channel speaker with two Boston A40's, but the comb filtering proved to be a disaster.

AR

[frankmarsi]

Comb filtering can be altered/corrected by using 'traps'.

In my travels I felt my LSTs were affected by many reflections 'pressurizing' the room so, I used two large foam traps that to my ears substantially cleaned-up what I felt needed to be corrected. One trap was placed in each corner and to my ears the result was pleasing and certainly a solution.

I might add that a parametric-equalizer would be a beneficial component. Aadams your equalizer appears to be what the same inexpensive one I purchased from R.S. in 1983. For the money it was acceptable to me however, presently it's not being used. When I installed the parametric equalizer I finally realized how much more it did to assist in getting the sound I was looking for whereas the 'graphic-equalizer' didn't add as much flexibility and I come from the 1970's school of thought that any equalizer was taboo and relegated my ears to enjoy the purity of AR's voicing. Ten years ago I purchased a TOTL mint 'Rotel' graphic and it's a beautiful piece but after using the parametrics I don't see any need for it although, in a flight of fantasy, I might in the future combined with the graphic-equalizer. 

Pardon this awful foto as it was cropped from a video I made while listening but, it shows what I'm speaking about.

 

[Aadams]

19 hours ago, AR surround said:

Did angling the Boston A40's away from each other eliminate any problems with comb filtering?

http://www.audioholics.com/loudspeaker-design/comb-filtering

 

AR Surround  I had to read about comb filtering to answer your question.   I would say that my term "lobing" was comb filtering.   I noticed the problem disappeared when I changed the speaker angle from 90 degrees to 45 degrees.   I also raised the crossover/transition frequency from a center on 125hz to a 250hz center, which may have had some effect. 

RE: 2 Satellites: The effect of using 2 CR65s was Ok but the BAs do not have the power response of the AR drivers and when I would rise from sitting in the listening spot I would notice a drop off in volume.  This problem was solved by adding a third CR65.  From my experience this approach does not work if you let all speakers run full range with zero equalization.  I am speculating here but the LST spectral balance control seems to have been a built in equalizer with 5 different settings where AR engineers carefully balanced the output of the eight dome drivers with the woofer output.  This is one reason why for this hybrid setup you need two equalizers and biamping. 

I will listen more closely for the comb filtering effect and report back.   

19 hours ago, frankmarsi said:

On another note, I'm a dedicated fan of the AR mid-range speaker as much I am of the AR-3a 12" woofer causing me to wonder if the sound quality you're speaking of with your stacking dissimilar brand speakers is of good quality.

FM  The different brand of speakers is not really a problem.  You can use the equalizers to timbre match and get the sound to the point where a instrument on a BA sounds like the same instrument  on an AR.  In my instructions above on timbre matching I recommend using a human voice because most of us are better at recognizing specific voices than specific instruments but either will do IMO.  The BA mids and tweets are still more detailed than my ARs but I can live with either and my other ARs are setup and on autopilot compared to this hybrid system that I am still not sure about with all of its angles and switches and knobs. 

Yes the two equalizers are 10 band RS units.  They cost more to ship than to purchase and they work well enough.  The equalizers are being used as gain controls as well as sound-shaping and timbre matching.  I am not sure a Parametric equalizer would allow me to do that.  1/3 octave units might be of benefit but would also add complexity. I have to live with this config longer before deciding.

Adams

[frankmarsi]

Adams,  just a quick note regarding what goes on with the AR-LSTs.

It uses a six tap transformer which will only equally adjust the woofer and the tweeters together.  The mid-range speakers remain constant and aren't affected and not varied at all.

I hope this info may be of some help.

[Aadams]

On 7/13/2017 at 1:31 PM, frankmarsi said:

I might add that a parametric-equalizer would be a beneficial component. Aadams your equalizer appears to be what the same inexpensive one I purchased from R.S. in 1983. For the money it was acceptable to me however, presently it's not being used. When I installed the parametric equalizer I finally realized how much more it did to assist in getting the sound I was looking for whereas the 'graphic-equalizer' didn't add as much flexibility and I come from the 1970's school of thought that any equalizer was taboo and relegated my ears to enjoy the purity of AR's voicing. Ten years ago I purchased a TOTL mint 'Rotel' graphic and it's a beautiful piece but after using the parametrics I don't see any need for it although, in a flight of fantasy, I might in the future combined with the graphic-equalizer. 

At the risk of hijacking my own thread I decided to address your post re tone controls in general and spectral balance on LSTs.  First , before your antennae and wings begin to buzz, you can stand down because I agree with you, which must mean we are correct? When I first  began listening to records I loved tone controls. After I began to spend real money I began to think tone controls really didn’t improve anything. Then, once I discovered the “straight wire with gain” cult, I became a purist that said tone controls were taboo and just another noise source, as long as one had good equipment and a proper listening environment.  For me, this led to so much frustration that I quit the hobby for over a decade and just attended concerts.  I only picked it up again one day when I was using a computer with headphones and discovered a software equalizer.  Short version is I am back and I still don’t use tone controls but I love equalizers. 

In summary, we should have been using equalizers from the time they became practical and affordable.

Adams

 

 

[Aadams]

There is an excellent bi-amping primer beginning on page 31 of the AR 9 reference manual in the library.  Hits all of he big issues of bi-amping for those who insist on bi-amping nines, or anything else.

[Aadams]

I had a long post ready to go about more listening but I decided to sum it up in much shorter post.  This hybrid evolved from an existing AR58 setup which can be restored at the push of a button so rather than focusing on Hybrid vs AR9 comparisons, I have spent a good bit of time listening to the original 58s system vs the Hybrid.  I was questioning whether my enthusiasm was still grounded.   It is.   While the 58 has the AR dome drivers, its weakness, as with all big three-ways, is the 12 inch woofer having to carry the critical human voice octaves.  The big difference between this hybrid stack and the 58s is the octave and a half between 200 and 700hz has been shifted to the 5 inch BA drivers and the difference clearly favors the Hybrid.  This also accounts for why I think the Hybrid sounds more like an AR9.     AR removed middle C (262hz) from the woofer beginning with the AR9 and all of their top systems were this way until the end.

[Aadams]

The system is still operating.  My, months ago, statement that tuning was at an end was premature.  I have tamed the overemphasis of deep bass and more importantly have discovered center balance is not obviously simple to achieve when systems are merged in this way with equalizers and power amps.  The BA CR65s have 4 gain controls that can affect left right balance while the AR58s have three.  What I have learned is identical index points for left and right knobs on the same unit of equipment are not necessarily the same.  Just because settings look equal doesn’t mean they are equal.   I think folks who bi-amp or tri-amp speakers even with identical power amps may sometimes face the same problem without knowing it.  When the LR center balance of the upper speakers differs greatly from the lower speakers it is obvious, but when they are very close to centered yet not aligned it is not easy to detect nor easy to correct by listening without a mono signal.   Correcting that last little bit of difference to align the center points makes a huge difference in the sound.   

My mistake was to assume all the gain controls were working identically and balance the left and right speakers as a group when I should have been centering each system separately before they were all engaged to play music.  My acceptance of the close but not correct setting for so long was, I think, because I was still thinking that the problem was with speaker placement or angles or perhaps this was just a bad idea.  Happily, the system is improved and for now the beast is tamer and easy to live with.

In my 11 steps above I covered vertical balancing of the separate systems but I ignored horizontal, left/right, because it seemed so obvious, but it is not.

I have attached an illustration that may help.

[Aadams]

Over the last three months this system has become my primary listening source.  I have always thought it sounded good but equivocated in recommending it as a solution to be duplicated by me or anyone else.  It never had operating problems, but it was a kluge that I wanted to simplify without spending a lot of money.   The system that was, is gone and has been reconfigured with one box added and five elements eliminated.

The new BLAST Stack has 7 operating drivers per side rather than 9.  The AR58 woofer is now crossed over at 200hz with the mid and tweeter being silenced electronically. 

The current configuration, which I foresee as permanent, is a pre-amp, single equalizer, and 2 DSP power amps each having an internal 24db/octave filter to crossover one amp to the woofers and the other to the satellites at 200hz.  The 3 satellites sit atop the AR58 cabinet configured as seen the accompanying photo.  The arrangement is akin to an Allison 1 or a DCM Timewindow. 

The lessons learned from setting up the previous system made this one ridiculously simple by comparison.  After verifying the wiring and power connections the only thing to do was

1.       Configure the amplifier crossover mode and specify the crossover freq.

2.       Balance the woofer and satellite loudness around the crossover point using test tones.

That’s it.

The sound: The AR woofer in the previous config, even though heavily equalized, was still operating audibly in its full 700hz range.  Now, sharply cut at 200hz, with the woofer virtually out of the human voice range, everything is much clearer but also spacious.  The astonishing bi-amp power available is a happy consequence that supplies huge overhead reserves.

OPINION regarding small satellites for MUSIC SYSTEMS: Whatever you use only need be good quality linear speakers that can be equalized to give the “AR sound” you seek.    A 6” or smaller speaker, whether acoustic suspension or ported, is almost never going to produce bass as well as a 12” at 100hz and when used as satellites will be high cut so steeply that mannerly roll off behavior at the extremes will have no bearing on the sound it contributes.   

And, because this is a non-destructive modification, I would have no reservation in doing this to any AR 3way 12inch, excluding a 3 series, and would consider it an upgrade.

[Aadams]

Also a great use for thousands of old Advents.

[Aadams]

Lots of options for speaker arrangement.  The pictures show what seems optimal and very pleasant in this room.  First one shows the 30 degree offset of the satellites.  The second image is the view from the center line.  I get a sweet spot up close and spaciousness when I move back.  This is far better than the first generation of this hybrid.

[Pete B]

Just wanted to let you know that the Sherwood AP-7020 Preamplifier has a built in

2-way active crossover that might be of interest.

[Aadams]

51 minutes ago, Pete B said:

Just wanted to let you know that the Sherwood AP-7020 Preamplifier has a built in

2-way active crossover that might be of interest.

Thanks. Check your feed.  Also your message box is full again.

Adams

[Aadams]

 From the beginning this has been an experiment.  One big concern was becoming so invested emotionally or financially that I could not admit failure or remain objective.

I avoided the financial problem by refusing to spend money on anything that could not be employed in another system or given away without regret.

The subjective, emotional investment was avoided by knowing that I always had 9s and 3as as reference and backup when I needed to calibrate my ears and if the experiment failed I would still have good sound.

Because I have not moved this system into a big room to assess it directly against my 9s and 3as, I will not say that it is an unequivocal success but, in this small 1000cft room I find myself frequently smiling at what I hear and am astonished at how little effort and time it would have taken had I known the direct path at the time I started.   

The cost.  If you have read the opening post to this thread you know the original cost included a new pair of powered sub-woofers for which I was willing to spend up to $1000 and was 80% of the budget.  Except where noted below everything else was purchased used or already in my possession.   After the sub-woofers were returned and this became a “Frankenstein” experiment the incremental cash outlay stood at around $200.  In its current and final form, the total expenditure is very close to $750 as follows:

Pre amp – Pioneer 850 that once drove AR58s system   

Equalizer- Realistic 10 band already in use with AR58s

BA CR65 speakers x 6   Approx $30 each

New Crown amp for 2 ohm load- $299

New Crown amp to isolate and drive AR58 woofer $250

New XLR cables $15

AR 58s – Previously used as separate system and AR9 standby parts bin.

Total incremental cost was $744

If the project had failed the Crowns would be used on my 9s and 3s so there never was real fear of failure.

Aadams

[Aadams]

I should give credit to a recent discussion in the AR forum for providing impetus to achieve this version of the system.  Had I not looked more deeply into the capabilities of DSP regulated amps as a result of that discussion, I believe this system would still have its previous klugey, less resolving, form. 

So, hats off to the CSP!

Adams

[ligs]

Adams,

I have been highly impressed by your dedication to better sound through experimentation.

I have been trying to blend speakers of different brands and sizes way back when I still owned a pair of AR9’s. I was looking for more natural sounding vocals and clarity in general. I liked the bass of AR9 but above the midbass, NHT Zero, Radioshack LX4(with Linaeum tweeter) and several other brands with stiff metal drivers sounded more natural to me. After I sold my AR9’s, I acquired a pair of NHT 1259(the woofer  in NHT 3.3). I also bought a pair of HSU Research TN1220 subwoofers capable of responding to below 20 Hz. Over the years I have paired many more commercial and even some DIY speakers to serve as tops to use with either NHT 1259 or Hsu. I have learned that there have been real advances in reducing the coloration and distortion of the drivers. Technologies such as symmetrical magnetic drive(JBL and Scanspeak), shorting ring for reducing the voice coil inductance(very common now), anodized aluminum cone(Ceramic) for stiffness, waveguide for tweeter and software for better crossover design, all were developed in the past 30 years. More recently, my favorite tops are Infinity R162 and R152.

https://www.soundandvision.com/content/infinity-reference-r162-speaker-system

Among the DIY speakers I like is a simple 2-way using Dayton RS 225-4 and RS28-A4.

I don’t think I have reached my perfect sound yet but I don’t want to stop experimenting either.

[Aadams]

4 hours ago, ligs said:

I have been highly impressed by your dedication to better sound through experimentation.

Ligs

Thanks for your comment. 

I am not a big experimenter I just fell into this by accident and from frustration with powered subs and their bias toward HT.  I was lucky to stumble upon a good result.    I listen to this system almost every day as entertainment and for evaluation to find flaws and have not changed it since my last post about satellite array positioning, but I will report my impressions in a few months either way.  I think I am being objective when I say It does sound good. The ultimate test will be to make myself move this system to a much larger room but there is too much inertia to make that happen anytime soon.

I agree, there have been huge advances in small speaker systems since AR left the field and there are a lot of good candidates for integrating into this type of system. 

Adams

[Aadams]

I have devised a way to overcome the inertia of moving this system to a much larger room, but I must wait until an amplifier is returned from being rebuilt sometime within the next 30 days.

This accelerated plan is possible because, for one time only I will violate my speaker ethics and experiment using my 3as as the bass speaker sitting beneath the satellite array.

Using this approach, I will only need to move the array and the very portable associated electronics to a position right beside the AR9s.

This is not a test of 9s against The Stack, rather it is a test to see if The Stack can produce a good sound field from a 15-20ft listening position while I am standing, sitting and somewhat mobile. 

More later.

 

Adams

[Aadams]

 

The BA/58 stack has been temporarily deactivated. The stack and electronics are now part of a new incarnation---------a BA/9 stack.  I know I said I would use a 3a but I realized it was logistically even easier to use the 9s and I learned something about using AR 4ways in the process.

First, if you do this with an AR 4 way you can cross at 100hz or 400hz but not at 200hz.   200hz seems perfect for a 3 way AR but the 4way doesn’t sound right because, as AR says in the AR9 manual, you will get some unpredictable effects.   AR foresaw that idiots like me might use an external crossover so, way back in 1979 they recommended 400hz for a woofer crossover point and partially explained why.   You could also cross at 100hz but that is a waste of an AR9. 

In the end, crossing at 400hz means you are effectively still running a 4 way system.

How does it sound?   I tried a couple of configurations you can see in the photos.  The listening position is 15ft away.  I could stand and move around with no dips or peaks apparent while listening to either large scale classical or pop vocals.  The vocals were solo recordings of male and female voices that I heard many times before on this satellite stack.

Does it sound like a 3a?  Close enough to where I could forget which speakers I had switched after a few minutes.  The amount of energy a 3a can distribute is astonishing.  Six drivers in this stack could not quite match its sound signature but sitting at 15ft listening, it is very hard to tell the difference after the switch is made.

This approach works in large and small spaces.