Simplicity & Luck & phase-plugs for the B200's ~

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-Richard-

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Simplicity & Luck & phase-plugs for the B200's ~
« on: 12 Sep 2007, 04:42 pm »
I am a minimalist. Which fits nicely with my admittedly lack of knowledge about all things electronic.

Recently I purchased a new Jeff Korneff 45 SET amplifier and Lloyd Peppard's Magic 5 Preamp. The sound
with my simple B200 OB's was very nice... however I gave into Dan Mason's suggestion to update my
B200's by inserting Planet 10's phase plugs. I found it relatively simple to cut out the dome-like stiff cloth
dust cap in the center of the B200's... David of Planet 10 provides nicely illustrated pictures on his web
site for this surgical operation. I used a simple No. 11 highly pointed triangular x-acto blade and then
carefully sanded the remaining fuzzy cloth and glue edges until they were smooth.

Then disaster struck... it seems no one who has written about the insertion of phase plugs into the B200's
has mentioned the very obvious beaming that results. I was using the CityPulse dac at this time with my
cheapy Pioneer "universal" player as the disk spinner. The beaming canceled-out the mid-range and
tipped up and spotlighted the upper frequencies. For me the sound could only be described as nasty.

Fortunately for me, Lloyd's Magic 5 preamp has 2 distinct operational modes (the passive mode sounds
very thin in my set-up... not a serious consideration). Lloyd describes it this way: A selector switch lets
you chose from a classic common-cathode + cathode-follower (CF), shunt-regulated push-pull (SRPP), or
passive path.

I was using the common-cathode+cathode mode which sounded marvelous with the original B200's.

The CityPulse has a very "intense" dynamic sound across the frequency spectrum.

I switched out the CityPulse and went back to my cheapy Pioneer as the CD player (Vinnie Rossi hates
the sound of this Pioneer)... still that awful beaming... perhaps a bit less noticeable.

I also inserted a roll of copper wiring (inductors) into the speaker cables to reduce the high frequencies
and flatten the lower frequency response of the B200's. That helped... but the upper frequencies now lost
some of their delicate shimmering resolution.

Then I switched Lloyd's preamp to the shunt-regulated push-pull mode... which Lloyd described to me as
really a Double-Triode configuration. Lloyd's preamp had just arrived so I let it burn-in.

2 days later something incredible happened. Everything started to come together.

I took out one copper inductor from the left-hand speaker and let it play naturally... however, I left the
inductor in the right-hand speaker... just to tame that upper frequency brightness a little.

Otherwise, I am not using any "active" EQ... and nothing (yet) to augment the bass cancellation that all
OB's experience.

Dan insisted that Jeff's 45 SET amp had tremendous bass presence... we are talking about a 2.5 watt
SET amp here based on a design that goes back to the 1920's... and now that prodigious characteristic
of Jeff's 45 amps appeared with remarkable intensity.

Gone is the beaming... instead there is now a marvelous top-end sense of space and delicate resolution.

The sound is the best I have ever heard... people with deep pockets and little imagination pay tens of
thousands of dollars for this sound... and never get it! Voices are THERE... IN THE ROOM! Instruments
have this remarkable real texture and lingering sonic presence after the last note is sounded... exactly
like they do in real spaces... there is this incredible space around everything... an ambient space that
"suspends" the voices and instruments in my room... tremendous explosive dynamics that gives
percussive instruments wonderful "jump"... and there is this something else... a wetness in the sound...
a liquidity... everything sounds wet and alive.

No need for a woofer. The bass is well fleshed out without any augmentation. And it is just as alive as
the mid-range.

And the amazing thing is that it is all a pure accident of sorts. Luck. And having a few options to play
with. If Steve Rayle had not sent me his beloved Magic 5 to try-out with my Korneff 45 SET amp when
it first arrived I would have had no idea of the power hidden in those 2.5 watts. And had Dan not
insisted I purchase Jeff's amp I would still be debating which 45 amp to buy. Thanks Steve, thanks Dan.

Those of you who would like to try Planet 10's phase plugs with the B200's should be aware that they
might beam unless your ancillary equipment is compatible with them.

I am sharing all of this with my fellow OB fans just to say don't be afraid to experiment and try
things out. Also... I am now completely convinced that there is no need for expensive drivers when
sound like this is possible. But it is necessary to make sure your amp and preamp are in harmony with
the OB experience.

Always with the Warmest Regards ~ Richard

mcgsxr

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #1 on: 12 Sep 2007, 08:14 pm »
Richard, a great read as always.

I did not notice any beaming once I installed the plugs in my b200's, and I too have noted (very happily!) the synergy that is so apparent when you hit on the right combo of amp, OB, and b200!

-Richard-

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #2 on: 12 Sep 2007, 08:54 pm »
Hi mcgsxr/Mark ~

It is always nice to read your thoughts and insights.

I did not notice any beaming once I installed the plugs in my b200's...

Yes... I reflected on this as soon as I read your post... it must be that your particular combination of
supporting equipment worked perfectly to synergize with the phase plugs... or perhaps my equipment
is prone to overly-energize the top end.

I respect your insights and judgment enormously Mark, so I am certain you do/did not hear any kind of
beaming... however... I thought it very important to advise everyone who is considering the option of
phase plugs for the B200's to at least take my experience into consideration... my experience could very
well be the exception... admittedly... but I like to share what I find out with everyone.

The most fascinating thing about my current set-up is that it plays small ensemble classical instrumental
music... like Beethoven quartets or Mozart quintets with the same vibrancy and aliveness that it plays
jazz instrumental music or ultra dynamic recently recorded music... this allows this usually detached
and somewhat recessive form of complex compositional forms to reveal its dance origins... so that a
great verve and articulate pacing keeps the music from becoming rhetorical or merely self-referential.
A great added feature!!!!

The visceral textural immediacy and intimacy of the voice is beyond description. Thrilling!!!!

And given what I think I am finding out about the nature of synergy in this pursuit of musical thrills
I am convinced that it is sheer luck that is at work... and "a little help from my friends" as the
Beatles say in Sargent Pepper.

Warmest Regards ~ Richard

corloc

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #3 on: 13 Sep 2007, 12:54 am »
I too had a little trouble when inserting the phase plugs on the B200's.  There isn't a lot of room for them. Once the phase plug was inserted I had to sit in front of the driver and move the plug around until  the cone moved freely.  I didn't hear scratching when the plug was out of place, but I didn't have a lot of bass and the upper frequency weren't right. 

Chris

scottw

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #4 on: 13 Sep 2007, 05:47 pm »
I think the PP's help to reduce the beaming or move the beaming up to a higher frequency.
The PP is blocking some of the wave from one side of the cone to the other and making an 8 inch cone beam like a 4 inch cone(I think this is how the theory goes). Maybe, if you were using much toe-in, the increased dispersion after adding the PP's may account for the increased upper frequencies at the listening position(this is a WAG).

When I installed PP's on my B200's, something didn't sound right. I found I had gotten a little lax about speaker placement. In my case/room I needed to remeasure distance and adjust the toe-in and now I'm pleased with the results. I think the PP's accentuated the need for proper placement.

Just some thoughts,

Scott

-Richard-

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #5 on: 14 Sep 2007, 09:22 pm »
Hi Chris and Scott ~

Thank you for sharing your experiences with phase plugs used with the B200's... it is helpful and important
to read your insights.

Every time something is implemented into ones OB system the balance of its constituent elements must
be reconfigured... that is the challenge of doing things yourself. However, the alternatives are not
particularly attractive. I have heard almost everything... not everything but very close to everything.
I am speaking as much about the heavily touted super duper expensive "you-know-whats" that garnish
all the attention of the audio press and the professional reviewers "wow's" and that admittedly look
rather fantastic design-wise.

I will not say these expensive overly rated "commercial" products sound terrible...
but to these ears they sound just ordinary... or "forced" in ways that I would not like to live with...
calling attention to themselves instead of providing excellent music reproduction.

So I am quite willing to experiment... to try all sorts of things in the service of getting that sound
that propels the music into that zone... that zone in which the music lives again... with all of its vitality
and dynamic essences intact. I am getting that so I know it is possible. Without expensive drivers.

I cannot believe that my experience is unique... I am certain that given a well executed amplifier and
preamplifier, joined with a CD player with some verve, the simple rather inexpensive B200's can provide
musical pleasures that no commercial speaker system I have ever heard can touch.

Perhaps someday I may delve into active EQ or add a larger woofer driver to the equation... why not?
But right now what I am hearing is extraordinary by any measure I would wish to apply.

Warmest Regards ~ Richard

gilbodavid

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #6 on: 6 Oct 2007, 06:35 pm »
hello Richard. i have been using the B200's OB for a while now, after the inclusion of Inductor and resister in parallel made them listenable for me (i use no digital equalization and listen mainly to jazz on record).  i have been playing through 70's sony amps that have tone controls that i can get good enough bass for me with them, and they are growing on me the more I listen to them, and the more i hear expensive commercial speakers at hifi shows. I think that amp synergy also seems to be important, and i seem to be nearing my final solution there. No phase plugs yet. I used to miss my Quad esl57's, but am not any more, which is a remarkable acheivement for these drivers.

I seem to be now getting really beautiful tonal textures, with stunning dynamic musicality (music lives and breathes through each note in a bar, with wonderful lilts available where otherwise it was rather monochrome pulses).  Also i seem to have found remarkable depth as well as width to the soundstage, giving that hologram view. None of this happened til i got the amp synergy going.

Regards, david

-Richard-

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Q
« Reply #7 on: 6 Oct 2007, 08:36 pm »
Hi David ~

Nice going!!!!!! Perhaps the biggest hoax in audio was the disappearance of tone controls and the
lame excuse from designers that it "distorted" the purity of the signal... it is not difficult for a
designer who knows what he is doing to give the end user a position on the preamplifier/amplifier
dial where the tone controls are not engaged if the "ultimate" "purity" is desired... and then allow
us to engage the tone controls to help to shape the signal to more perfectly match our speakers, the
recording, the room, the CD or DAC, the tubes we are using (if that is the circuitry being used), the
music we are listening to, the volume we are listening at... quite a list of variables that tone controls
can help to bring tonal control over.

But designers got lazy... and we audio buffs allowed them to get lazy... and then we bought into the
idea of "purity" of sound which is a total illusion... there is no such thing as purity of sound... the
music either comes alive and lifts itself out of the myriad devices used to reproduce it or it does not!

If we are talking about the reproduction of classical music written for small ensembles... that is
meant to be heard unamplified... then that is a particular genre that takes enormous care to
reproduce in ones system without injuring the delicate tonal qualities of the instruments and to
gather the ambient space in a convincing way. Certainly worth while... and that is one particular
interest of mine since both Deborah and I listen to small ensemble classic music a great deal...
and we regularly attend local performances in Santa Barbara during the summer when students from
all over the world perform for free at the SBMuseum auditorium.

But there are many genres of music that are not meant to be listened to in that way... music that
uses electronically amplified instruments for example.

The B200's can easily be influenced to generate all the bass the music requires with the help of
a bass tone control... which I proved to an audio designer in his own home one day... he nearly
fell on the floor when I added bass from the bass tone control and the B200's reached down into
40Hz region with no problem and no distortion.

I have 3 pairs of 45 tubes that I alternate in my Korneff 45 SET amp... if my preamplifier had tone
controls it would not be necessary to alternate between these shockingly expensive tubes...
because what they are doing is essentially controlling the upper and lower frequency tone... a job
better and infinitely less expensively accomplished by tone controls.

Many owner of the B200's use active EQ... from cheapy (relatively) EQ devices like the Behringer
to very pricey ones like the new Ranes. But all of them have op-amps in them and one is forced to
complicate the signal path by using them. What they are doing is exactly what tone controls used
to do.

I am very happy for you, David... I know what you are hearing... a sound that saturates ones room
like live music... a sound that boxes are not sapping of their vital energy... a dynamics that are
not constrained by the boxes need to "control" the back wave... and so on.

I am glad you are sufficiently free of audio hype to allow yourself... to give yourself permission to
keep exploring until your B200's and ancillary equipment yield the musical life you are looking for.

Again... nice work!!!!!

Warm Regards ~ Richard

EProvenzano

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #8 on: 17 Oct 2007, 05:39 am »

Hello,

Does anyone here have any regrets after installing phase plugs into your B200's?
Is everyone in agreement that the sound is not only different but better in most regards?

Thanks  :thumb:

-Richard-

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #9 on: 17 Oct 2007, 04:01 pm »
Hi EProvenzano ~

I tried to suggest that it may not be quite as simple as a yes or no to your question...
yes phase plugs are better... no they are not.

What the phase plugs do is to release the B200's ability to render upper frequency
information... so depending on your amplifier, preamplifier and CD (or Dac) player
what you hear can be exquisitely rendered and nuanced upper frequency musical
information... or it could sound quite unpleasant... causing a very irritating and
agitating physical experience.

Using a tubed SET amplifier like my Korneff 45... or Vinnie Rossie's Signature 70 with
Lloyd Peppard's dual circuit Magic 5 tube preamplifier works pure magic most of the
time in my listening room. If the CD's engineer fell asleep in the studio... or cared little
for how the original music was translated to the CD... and therefore did not carefully
"tame" the upper frequency musical material... then nothing is going to help! short of a
steep rolling off of the UF material with the use of an active or passive EQ.

There are many times when I think that having an active EQ... like the new Rane gear
or something comparable would give me the option to fine-tune the sound to a much
more "resolved" sense of "rightness".

But I am lazy... and my budget is currently almost non-existent... so instead of buying
more toys I am listening more intently to hear what I could do to solve any issues I
have with the sound in the simplest way possible.

What the B200's with phase plugs do in my simple set-up is really astounding...
transparency, throbbing intense dynamics, a mid-range that is palpable and alive
with complex harmonic textures, details that come alive as real music, voices that
are rich and warm and fully present... but I have chosen my ancillary equipment with
that kind of sound in mind... that and a great deal of luck.

Oh yes... it is helpful if you have serious audio friends to help you to think things through.

The amount of hype and misinformation in audio is endemic... and is singularly responsible
for huge amounts of money and time misspent chasing nicely packaged illusions.

Warm Regards ~ Richard

scorpion

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #10 on: 17 Oct 2007, 10:12 pm »
Hi Richard,

Good to see you here. Regarding Dave's Phase Plugs there are mostly unanimously approved. But measurements do not really give them allover dominance.
Visaton themselves were not in favor of Phase Plugs, they stated it was tested and not giving any significant improvement. I think it may be mostly a subjective matter,  good or not.

However, I have been playing with my B200s quite a while now and for me they seem to have improved in the upper frequencies over the time, not perhaps in dispersion but absolutly in overall response.

If you still do not use any frequency alteration on your B200 why not test the 1 mH + 8 Ohms LR circuit, it would certainly be of interest to have your reaction to that.  :scratch:

/Erling

EProvenzano

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #11 on: 17 Oct 2007, 11:34 pm »
Thanks Richard.  :thumb:


If you still do not use any frequency alteration on your B200 why not test the 1 mH + 8 Ohms LR circuit, it would certainly be of interest to have your reaction to that.  :scratch:

/Erling


Erling,
Would you elaborate on this a bit more for me?  I'd sure appreciate it if you could explain this filter (?) in laymans terms.

I currently own the B200's, and while I find them sublime in many regards the frequency response is too forward for me to live with long term.

Ultimately, I will add a sealed woofer to operate up to 100-150hz (?), and the phase plug seems easy enough to install, but first I want to be sure it will be an upgrade rather than a subjective change.  Before I make a subjective move, I need to live with my new speakers for a while.

EP




EProvenzano

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #12 on: 17 Oct 2007, 11:42 pm »
Nevermind!  I found this thread:

http://www.audiocircle.com/index.php?topic=31582.0

Hell I even posted to it :duh:.
I was interested in this topic a long time ago but it was over my head.

 :thumb:


-Richard-

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #13 on: 18 Oct 2007, 01:06 am »
Hi Erling ~

I have read many of your posts on AC and always found your insights and measurements
extremely helpful, well-informed and generous... we are all indebted to you for your
careful attention to everything that matters in the realm of OB's.

Vinnie Rossie read your first post that suggested that the use of filters on the speaker cable
improved the sound of the B200's and after trying it himself concurred with your findings... and so
he strongly suggested I try it as well which I did.

I assume the filter is used to flatten the bass response and presumably help to tame the
rise in the upper frequencies... is the 1 mH + 8 Ohms LR circuit describing the value for the
inductor as 1 mH and a resistor of 8 Ohms? is that correct, Erling?

The parts I am using do not have value markings on them so I am not certain if I got that right.

I originally liked what the filters were doing... now I am not certain... I have gone back to the
B200's without the use of any filters... very very dynamic. However your suggestion has once
again peaked my interest... I will definitely try them again in the next day or so. Thanks for
the gentle push in that direction... perhaps it will do a bit of magic with the phase plugs.

May I suggest that in terms of my own experience the insertion of Planet 10's phase plugs
into the B200's is not merely subjective... it opens the top end in a dramatic way... the
effect is unequivocal and real... but whether or not it is a "good" change or can be
considered an upgrade is indeed subjective.

Right now I seem to have the sound somewhat balanced in the favor of using the phase
plugs... but it means not being able to use the best 45 tube I have... rather I have to use
the horribly expensive Emission Labs tubes which are strangely rolled-off on the top
compared to my NOS RCA tubes... a change in CD player or dac might be the perfect
solution to this high frequency spotlighting... but it must not be anemic like the Monica
in order to curb the nasties... so I am open to suggestions of what CD player or dac
might be a perfect match... meaning really refined on top without rolling off the highs
to accomplish it.

My B200's are quite mature... I have had them playing everyday for 3 years now...
I suspect the very highly-priced drivers out there... the Alnico and field coil speakers
which are often held up as the best that money can buy... are not significantly better
than what I am hearing in my living space. Actually the sound I am getting is quite
fabulous... I have not yet chosen a sub to go with them... and I am very interested
in working with a pair to augment the lower frequencies.

However I am concerned with the need for a cross-over... active or passive...
and I am not certain what bass driver can keep up with the electrostatic speeds of
my B200's... any thoughts, Erling?

Viston has given us the gift of a rich musical experience on the cheap... and I am
deeply grateful to them for it.

Incidentally, Erling... are the new "versions" of the B200's audibly better sounding
then the previous iteration?

Thanks for all your generous help and generous sense of community, Erling.

Warm Regards ~ Richard

markC

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #14 on: 18 Oct 2007, 01:41 am »
Richard,
Let me start by saying that I respect your long term input as well as the way that you submit your thoughts, but I can't disagree with you more about changing your associated equipment to suit your speaker's presentation.
IMO, a speaker should be able to perform to levels that will "do it for you" without  specific components.
I like tubes; and I test my speaks with other tube equipment when possible. To be able to discern the difference in a cdp or dac comparison, (such as high end clarity for example), the speaker should be the constant.
Wait a minute, I sound like I am agreeing with you!
Try the LR circuit again with known value components and don"t forget to add the zobel.
I think You'll like it.

-Richard-

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #15 on: 18 Oct 2007, 02:59 am »
Nice post markC... I admit your sense of humor had me reading it a few times... sort of like
a zen koan... the zen masters devised ways of presenting the truth in the most agile, fluid
and ultimately ephemeral way that language can be used.

I agree with you that our involvement in audio is more often than not inconsistent with
whatever previous views we thought we had until something in our experimentation proves
it no longer valid... that has characterized my own explorations... all accidents and just plain
luck... and a great deal of help from AC members like yourself... whom we are all fortunate to
have in our "collective" community.

OK... my love of music is not matched by my knowledge of electronics... although I am
learning some things as I go along... so what exactly is a zobel, how does it work and do
I need to know the values of the parts? Or am I quite far from the meaning?

Thanks for your feedback and help, markC... great to hear from you.

Warm Regards ~ Richard

scorpion

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #16 on: 18 Oct 2007, 02:11 pm »
Hi Richard,

Thanks a lot for the kind words. But there are some very capable persons contributing here. For instance Rudolf's last posts regarding bass excition of room modes made me change my bass angle to have the back firing directly into the room corner. In fact it seems to be 'subjectivly' better.

The simple LR circuit which Visaton have in all their designs for the B200 with quite differing values was a resulting compromise of some different setups. What it is doing is to take down the rising treble response to match the bass output of B200. Very simple and yet effective.

Myself I have joined Dr Mason in going totally digital. In fact this will open up a window of even more direct and appealing sound. I have used the Behringer DCX2496 and this unit is giving a very good performance in stock form. However it can be tweaked. The last is a complete Kit to make it into a formidable preamp with 6 channel volumecontrol and pratically distortionless. I will probably do this tweak because the Behringer is so good in itself. I do not think that any non oversampling design will match it in the first place. However the price of the tweak kit is on par with the unit price of the Behringer.

I think that MJK's forwarding of Eminence Alpha 15s just hit the point in OB design. Evidently they are also the units used in Emerald Physics new CS2 speaker.
They will allow for somewhat slim OB panels, with some reservation. I think that MJK's own what I have named 'Topless U-baffles' is a very practical and non-resonant design for bass-baffles that should be more carried forward than now is the case. Infact a bass baffle of dimensions 28 x 40", 28 high and 40" wide including wings with one Alpha15 will match the B200 perfecly in level.

Yeah, go back and try the LR-circuit. It won't hurt.  :)

All the Best,

/Erling




scottw

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #17 on: 18 Oct 2007, 08:08 pm »
Regarding the LR circuit, if you try it, get some good resistors like Mills 12 watt non-inductively wound resistors. To some, MOX resistors(at least the typical ones I've seen used in crossovers) are akin to using a standard electrolytic cap in a tweeter crossover. Not good.

Scott

markC

Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #18 on: 18 Oct 2007, 09:27 pm »
Ah yes Richard, all in good fun. Who ever said audiophiles are a bunch of stiff shirts?
On to the filter circuit.... I personally use a 12 ga. 0.68 mH Alpha foil inductor in parrallel with a Mills 12W 6.8 ohm resistor, (the LR circuit), and a 13 uf Sonicap capacitor in series with a Mills 12W 6.2 ohm resistor, (the zobel). The zobel is installed across the + and - just b4 the driver. Give it a try- you can use cheap parts to get an idea of the effect, but in my case it was a waste of money as I soon replaced the cheapo's with the above mentioned ones and it was worth it- especially the inductor.

-Richard-

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Re: Simplicity & Luck & phase-plugs for the B200's ~
« Reply #19 on: 22 Oct 2007, 07:53 pm »
Hi Scorpion, Mark C and ScottW~

Thanks for further information on the LR circuit and for sharing the values on the inductors and resistors, as well as the zobel information. I still do not know what the zobel is used for?

OK... I found and hooked up the original (cheapy parts) LR circuit based on Scorpion's values.

The upper frequency air vanished... a more "balanced" but flatter sonic perspective was introduced with the addition of the LF circuit to both B200 drivers. Gone was that extraordinary sense of the music being alive... full of the ambient spatial air of the recording venue.

Then the lightbulb went off in my mind... what if I removed the phase plugs (from Planet 10) and just left the center voice-coil former (center well) of the drivers open?... no dust-cover, I removed that in order to insert the phase plugs (the phase plugs sit in the center well by the use of screw-heads that respond to the magnetic pull of the drivers magnet).

That works! Without the phase plugs in the B200's former and with the addition of the LR circuit the sound is smoother and the upper frequency "air" has returned to impart that marvelous sense of real music played in real spaces... which is the essence of the magic I hear with my present set-up.

So that makes me wonder... it could be that the dust covers on the B200 are absorbing some of the air that would otherwise be present without them... veiling the sound somewhat (?)

I suspect that as MarkC suggests, a higher level of parts would produce a higher level of resolution in what I am hearing... a bit more refinement in the presentation... but at least I am getting a sense of what the LR circuit and no phase plugs sound like.

My observation is that the phase plugs were contributing to a spotlighted presentation of the upper frequencies... without them the upper frequencies seem better integrated into the all-over gestalt of the music... less "directional" and more integrated... much more "air".

Scorpion... you mentioned that the Eminence Alpha-15s was used in the Emerald OB's... I wonder if that was a misprint or a special order Emerald had built for them... I called US Speaker and Al told me that Eminence only makes the Alpha-15a... there is no "s" version available according to him. Any thoughts on that?

If you meant the Alpha-15a... I looked at the frequency specs: 46Hz to 3.5KHz... I was wondering how one can generate more bass than 46Hz? even assuming there is a 12db drop when the Alpha-15a is producing frequencies in the mid 30Hz region (which is something one could presumably hear)... would a bass "boost" allow the Alpha-15a to go lower?

Or do you feel that 46Hz is enough for OB effectiveness?

I love the sensitivity of the Alpha-15a's... 98spl... that should keep up nicely with the B200's!!!

Any more light on this would be most helpful.

Thanks everyone for your kindness and help. I deeply appreciate it.

Warm Regards ~ Richard