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« on: 16 Dec 2005, 06:50 am »
I want to share with everyone that I have experienced a true revolution
in SET tube amplifier design. And I am very, very excited about it.
All of us have become very good friends over the past few years.
Sharing our thoughts, insights and discoveries with each other. I want
to share an experience I had yesterday with Roger Modjeski, of Music
Reference, who DMason rightly calls the “Merlin of Tubedom”.
A little background will help to create a necessary context for
my excursion into the Santa Barbara hinterlands where Roger’s
home/laboratory resides.
I have been researching Single Ended Triode tube amplification
for quite some time to see what magic, if any, these classic tubes which
go back to the beginnings of audio's evolution, could bring to my
Visaton B200’s in Open Baffle configuration.
Many of you will remember the thread DMason started several
months ago entitled Gravity Well of a Dark Star...


started in Red Wine Audio’s forum, in which Dan shared with all of us
his findings that a pair of B200’s set in a simple plywood panel constitutes
an entirely new paradigm in audio reproduction. Those of us who took
Dan at his word went ahead and ordered the B200’s and designed our
own baffles based on information Dan shared with us. The result has been
nothing less than a transformational shift in everything I thought I
understood about speaker design. And the beginning of a totally new
relationship with what is possible in reproducing the pulsating musical
life within the live event of music.
My interest in SET tube design has lead me to appreciate the
individual genius of each person who has undertaken the challenge of
creating their unique designs in amplifiers built around the potential of
such classic Single Ended Tubes as the 45, 2A3, and 300B.
Some of these designers are legendary innovators who have
brought their considerable genius to problems and challenges of
advancing the potential of SET amplifier design using these tubes.
The drawback for many music lovers in exploring SET amplifier design
has always been the low watts generated by these tubes. Roger Modjeski
is one of these legendary geniuses who has now developed an entirely
new circuit that does what no other designer has been able to do...until now...
he has developed a circuit that can actually allow the 45 tube to play at
twice its usual watt power rating, bringing it within reach of highly efficient
speakers like the B200’s with their 96db sensitivity. That means that the
usual range of 1.5 to 2 watts, which is the only range that all of the existing
45 SET tube amps can generate, is doubled in his extraordinary revolutionary
SET amplifiers. The result is a 45 SET that can generate 5 watts of clean,
highly detailed and explosive power!!!! And his circuit innovations do not
stop with the 45, but he is able to double the power output of 2A3’s and
300B’s as well. Roger’s circuit in no way “pushes” the tube to perform
past its safe range. This "Merlin of Tubedom" does his magic purely with
circuit innovation that does not affect the life of the tube. In fact Roger is
the only one in the business that guarantees his tubes performance for
a period of 12 months or 2,000 hours (whatever comes first).
     When I first entered Rogers home/laboratory (Picasso once said
that “every room of my house is a laboratory”...and that is certainly true
of Roger as well) he was playing an older pair of AR3’s with his new
State-of-the-Art “Flagship” (Rogers word) RM-245. If I say that this amp
looks gorgeous in person, most of you will think I have gone over the edge
and lost all control of my mind. Well maybe I have. I love the looks of this
thing...with every control...and there are lots and lots of controls...placed on
top of a large polished black surface. The sides are a lovely dark wood.
Take a look at it on Rogers web page...


Roger designed this amp to allow for dialed in negative feedback (or no feedback)
and variable biasing adjustments. What this does is to allow the amp to play
any kind of 45 tube out there and any speaker that is designed to play driven
by 5 giant voluptuous 45 SET watts. The RM-245 cost $6000.00...a price most
of us are not able to afford. But the good news is this. Roger has also designed
a much less expensive version that will sell for less than $2000.00. And there is
another even more powerful 2A3/45 SET amp that has even more power for
less than $3000.00. Both these amps are a steal considering the doubling of
power and the versitility of both amps being able to play 45 and 2A3 tubes.
We listened to the AR 3 for a while and then Roger asked me to bring
in my B200’s and set them up. We moved the AR3 out of the way and I set up
my 3/4 inch plywood panels with the B200’s mounted somewhere near the top
and flush to the front surface of the wood. A friend of Roger’s, named John,
walked in and he and John admired the look of these simple yet elegant panels.
Roger hooked up wires to them and we listened. The first thing I noticed was
that there was nothing happening below say 200 Hz. This came as a shock
to me because at home, driven by my 9 year old Single Ended Pentode
integrated amp I had never missed that frequency range before. But then
my SEP integrated has tone controls and I usually dial the bass in to
somewhere around 2 or 3 o’clock. For the record, when I was auditioning
Louis Chochos’s new Aperiodic 8’s at home recently, it became obvious
that these tone controls are C-R-U-D-E. The Aperiodic 8’s are so revealing
that the tremendous distortion my tone controls produced made it impossible
to listen to the A8’s without taking them out of the equation. Which suggests
the B200 in OB configuration are much more forgiving and less detailed then
the A8’s in absolute terms. Roger explained to me that the bass tone control
of my SEP was forcing the B200’s into an excursion that moved it out of its
natural linear range...which was not good for the B200...even if it was
able to produce some of the lower frequencies.
John was immediately taken by the sound of the B200’s which
filled Rogers room with a penetrating realism that was captivating.
Roger listened intently for awhile.
Let me digress by saying that I really like Roger. He is funny and
very serious at the same time. He waxes quite eloquently about every
detail related to circuitry, tubes, speakers, power, you name it, and all
the while Roger speaks in a staccato stream of fascinating ideas that
opened up, what for me, has always been the cloaked mystery behind
audio’s real science. Additionally he is warm, sincere, friendly and very
enthusiastic. Suddenly Roger jumped up and pulled a small sub woofer
from behind a pair of his own electrostatic speakers that he has been
working on. He also pulled out a small amp with its guts exposed
(“...I call  it my Saturday amp because I threw it together one Saturday
to play my new subwoofer...”) and a slim device Roger identified as a
“active crossover”. He ripped the back open from the active crossover
and pulled out what looked like a pair of computer sound cards and
then fished in a shoebox full of similar devices until...“There!...that should
create the perfect crossover for these speakers”. He popped them in
rerouted the wires here and there, placed the subwoofer in front of the
2 OB panels and turned everything back on again. He moved with such
speed and certainty that I could barely follow everything he was doing.
When the sound came back on something very strange happened.
The sound field  of the B200’s in OB, played by Rogers RM-245 with
the huge EmissionLabs 45 tubes, sounded like we were listening in a
huge theater with vast spaces. I could here to the back wall of the
recording venue. Every detail that was present in the music appeared
from a spatial field so dense with musical information that I was truly
astounded. Is this what DMason has been talking about all this time?
I wondered to myself. My god! John and Roger were as mystified as
I was. The marriage of Roger's 45 SET amp generating 5 powerful
watts and the B200’s in OB cannot be believed. Roger put on one CD
then another and the response was always he same. Voices were to
die for. Rich, resonant, really there in the room with you, palpable, you
could hear the humanity, the aching emotion, the reflective ebbing and
commencing of the voice as it  wound its way around the heart strings.
Instrumentals were rich in timbre, detailed, layered. The B200  sounded
like HUGE horn speakers. I should know. I had just returned from the VTV
show and heard the humongous Cogent speakers that you could crawl
into and live in...no kidding! And Rogers amp and the B200’s sounded
John was a very nice chap and listened most intently. He was
easily in his sixties if not older and has a pair of Apogges and amplifiers
modified by Roger. He was really impressed and kept saying how incredible
they sounded. Roger took copious measurements of my baffles. He has
every intention of experimenting with his own pair of OB’s using the
Finally Roger put  on a CD of Bach’s organ works...and turned up
the RM-245 all the way. He placed an oscilloscope on the floor hooked
up to the amp and speakers...and we listened to a full organ emit sounds
that were comparable to what I heard in Chartres Cathedral in France.
But with a clarity of tone that must be experienced to be believed.
The bottom line is I am purchasing one of Rogers lesser expensive
amps. Probably the 2A3/45 which is a smaller version of the RM-245 45
SET but larger than the scaled down 45. Both amps will play both tubes.
Before I left I asked Roger to put the EmissionLabs 2A3 tube in
place of the 45. In Rogers amp the usual 3 watts of the 2A3 actually
generates 8 watts of SET power! What I heard was revelatory. The 2A3
was actually more detailed and perhaps even smoother than the 45.
Something that is supposed go against popular wisdom. But both tubes
sound so incredible that I am still shaking my head in disbelief.
Something happened to me at Rogers house/laboratory. I heard
music reproduced as I have never heard it before; alive, rich, layered, spatial
and detailed, with a natural warmth and dynamics that was revelatory.
Anyone who has ever wondered about what a well executed 45 or
2A3 amp can sound like on their speakers...assuming their speakers have
the necessary sensitivity...will be truly amazed by what Roger Modjeski
has done with his new SET amplifiers. I was thinking about the Yamamoto
A08S because of the raves Srajan and Jeff Day said about it.
MOVE OVER Yamamoto. Here is a true legend of American audio,
Roger Modjeski, who has developed a SET amp that delivers TWICE THE
POWER from the same tubes and gives enormous control over biasing and
even negative feedback, or no feedback, as desired...for less than the Yamamoto...
and does not use a rectifier tube. And Roger’s circuit design has good control
over damping which means good control of the speaker and a very low noise floor.
It is important to point out that the Yamamoto uses the 717A tube
which will become increasingly hard to find. The 80 which is their rectifier
tube, it is already expensive and becoming rare. This constitutes built-in
obsolescence. And I like the design of Roger’s new SET’s much better.
Thanks Roger for teaching me more about amplifier circuit design
in a few hours than I have been able to learn in months and months of
reading. Thanks for letting me listen to your magical amps and sharing
all of your insights with me.
I will be putting in my order for Rogers 2A3/45 amp...and...for his subwoofer...
which is small, fast as hell and is hardly noticeable...but which fleshed out the
B200’s perfectly...keeping up with their tremendous speed with perfect aplomb
that never called attention to itself. Roger is thinking that the subwoofer with
amp and active crossover should sell for around $1000.00.
I shall be reporting back to everyone as soon as I have Roger’s
new 2A3/45 amp and subwoofer in hand and playing at home.
I strongly urge anyone who is even remotely interested in Single
Ended Triode tube designs to get in touch with Roger or his assistant
Sage. 805.687.2236.
Roger thinks he will have photos of his new less expensive versions
of this 45 SET and 2a3/45 SET up on his web site before the end of January.
Real revolutions do not happen very often. These Revolutionary
new SET’s are the real thing.

I want to wish everyone at Audio Circle a Very Merry Holiday. Peace on Earth.

Warm regards -Richard-


« Reply #1 on: 16 Dec 2005, 07:39 am »
Another beautiful story, Richard.  Would love to hear that setup some day.  My own room arrangement isn't permitting anything of that kind, and I am already considering building another speaker design to further explore the realms of audio reproduction.


« Reply #2 on: 16 Dec 2005, 09:27 am »
Richard...that is a great story! I owned one of Rogers tube amps in the past.Very very good stuff.
I knew once you heard those speakers with some bass integrated in you would understand what the lower frequencies do for the music.It puts space and depth in the recording where it's missing in a non-full range speaker. It's not there to rattle your bones  :lol: . Some of these guys have no idea what their missing using speakers that only go down to 80 or 60 hz.

Good listening!


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« Reply #3 on: 16 Dec 2005, 01:04 pm »
Iindeed, a great story there Richard.  Do you have tweeter with your OB B200's or, just the B200's?


« Reply #4 on: 16 Dec 2005, 03:14 pm »

Thanks for sharing your experience with the 2a3/45 amps.  Both of those tubes have been favorites of mine - and it sounds like Roger has worked some magic with them.

I really can't wait to hear the B200's.   Can you offer any comparision between the B200 driver in open baffle and in the A8's?



« Reply #5 on: 16 Dec 2005, 03:38 pm »
Not trying to detract from this in any way, but I am not so sure I buy into the point about this being a revolution.  This is because he is acheiving higher power by using the EML's 45/2A3 variants.  The EML 45 by all accounts is a fantastic tube, but it really isn't a 45.  It may be able to be used in *some* 45 circuits but it does have different electrical characteristics therefore it isn't a real 45.  

Same is true of the KR tubes.  The KR845 or 300B puts out a whole lot more watts than their kin, but they are also very different tubes that happen to have similar characteristics that make them like their kin.  IIRC, the KR tubes parrallel a bunch of the "guts" of the tube thereby effectively adding multiple parrallel tubes inside each tube.  

I am investigating building some triode amps and I plan to use some EML tubes, so I am not dissing them.  The break-through has been a technological advancement in the tube technology not the circuit design, which is still pretty well paved.


« Reply #6 on: 16 Dec 2005, 03:40 pm »
Bravo!  It's a tie!!


Any word on the A8's vs. the open baffles?  Detailed vs. diffuse, anything else?


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« Reply #7 on: 16 Dec 2005, 04:07 pm »

What a wonderful recounting of what must have been a day of wondrous sound and music! I know how patiently and carefully you have conducted your search for a new amplifier, and what incredible good fortune it was to have Roger living close by so that you experience this yourself with your own speakers. I'm hoping you get your amplifier and subwoofer soon so we can get further reports...very, very exciting news!


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« Reply #8 on: 16 Dec 2005, 06:09 pm »
Hi JoshK,

I know it seems to go against our conditioned response of what is possible in
SET tube design to think that a designer could find a way of doubling the power
of ANY 45 or 2A3 tube by optimizing the circuit. But that is precisely what is going
on here.

Roger is not using the extended power capability of the Emission Labs 45 tube.
In his own words:

"...If I did I would get about 8 - 10 watts. It is the circuit and the tube application
that I have created that does this. If you refer them to the graph at 6 moons or
on our website, they can see this clearly.


I should call this a 4 watt amplifier.... George misadvertised me yesterday,
and I didn't check. My mistake. I'm a stickler for correctness..."

Roger really has created a REVOLUTIONARY new 45 and 2A3 SET amplifier
that recreates music with a spooky, uncanny, 3-Dimensional spatial field that
gives immediacy and life to instruments and voices in an all-over gesthalt of
organic cohesiveness...

That is what I heard using the B200's in Open Baffle configuration.

It must be heard to be believed!

Warm Regards -Richard-

Roger A. Modjeski

« Reply #9 on: 16 Dec 2005, 06:22 pm »
I would like to clairfy the power issue on the RM-245, but let me tell you a little story first.

Over the last 10 years I have written several new applications to get higher power out of some common tubes that I thought could do more. If I were employed by Sylvania in the 1950's-70's I would have done the same thing. There are an infinite number of applications that can be written for any given tube. They involve variations in B+ voltage, current, grid drive, screen voltage and load impedance. The data books list only a few to give amp designers some ideas. Sadly, that's as far as many designers go. David Manley was a stickler for applications believing that the only ones allowed were the ones in the data books and they must be adhered to the letter. Sadly, he took the ambitious 560 Volt Ultra-linear application from MOV as reliable  and made some amplifiers that damaged a lot of tubes. Not even MOV could make tubes that consistantly held up in that application. To this day there are no tubes that hold up well at those voltages on the screen.

I research my applications very carefully with dissipation studies on all elements. And, although I have a replacement tube business, I do not want to waste valuable tubes (or your money) on poor applications.

One application that caused a lot of comment in the Asylum was my getting 35 watts out of a pair of 6BQ5/EL84's. They said it couldn't be done, yet it is done and has proved reliable over the past 10 years in the field.

The RM 245 uses a new application that yields 4 watts at a dissipation of less than 8 watts. There is no extra stress on the tube. Typical applications are 10 watts dissipation (the max for that tube).

If you look at the following link, you can see the power vs distortion for 3 tubes at 25 mA. and the EML at elevated current where we take advantage of some of its extra dissipation. I have not yet written the maximum application for that tube, but I expect to get 8-10 watts at low THD.



« Reply #10 on: 16 Dec 2005, 06:36 pm »
Let me be the first to say, "welcome Roger!"

I too agree that running tubes at 60-80% their max dissapation is a very good idea and should be adhered to more often. I also am aware that there are many tricks/applications/implemenations that a designer can do to achieve more from a fairly simple design.  

I am not dismissing your design abilities at all.   I was just trying to make the point that the tube allows this to happen but allowing more headroom.  I think we can agree that squeezing 4 watts from a NOS 45 while keeping dissapation at 80% is pretty much a loosing proposition.


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« Reply #11 on: 16 Dec 2005, 08:56 pm »
Hi rnhood,

The Visaton B200's are a wide range speaker...so I do not use a tweeter with them.
Perhaps in ultimate terms...of what is possible in treble extension using a good tweeter...
the B200's may appear to lack some sparkle on top...however that is not what I hear.
The B200's resolve the top end beautifully with a lovely non-etched delicacy that my ears
find deeply satisfying.

The concept behind using a wide range driver is the cohesiveness they give to the
all-over gestalt of the musical performance...by that I mean that the voices and
instruments appear before you as if they are part of a single fabric of sound...
an all-inclusive space...and perhaps most importantly...instruments are not "broken"
by the separate drivers and their crossovers the way they are in multi-driver systems...

Perhaps there are many members of AC that use multi-driver speakers and may
feel somewhat put off by what I just said...please don't be...I have not heard every
multi-driver system out there...I am speaking generally here...it is very difficult to
describe what a wide range driver is doing that a multi-driver system does not do
as well...perhaps the brain is relieved of the subtle yet stressful task of putting the
all-over sound back together again that multi-driver systems necessitate...no matter
how well implemented they are...

When one starts out listening to reproduced music on very highly resolving systems
there is a thrill that is hard to duplicate by any other media...a thrill that goes right to
the nervous system and for all I know may even produce endorphins, or their equivalent
in the brain...there is also the consideration of a certain tribal emotional experience that
we have not entirely forgotten that may find its aesthetic echo in highly resolved music

Over time our ears adjust to this phenomenon and we begin to make more and more
nuanced observations about what we are hearing...we become ever more discriminating
in our sense of what brings us closer to the experience we seem to crave in our musical
life...it is because of this inherently human process that the world of High End Audio
products are born...and thrive...as a business...

After years of listening to a great many speakers and amplifiers I have come to make
certain choices that seem to be deeply satisfying to me...not only to me...but to my
wife Deborah, whose hearing has much more acuity than mine...more sensitive and
perhaps even more  discerning...

Both of us respond most emphatically to wide range speakers driven by SET tube
amplifiers...it is not merely the level of resolution this combination offers that compels
our interest...it is the deeply emotional satisfaction it delivers to voices and instruments...
and the intelligence...the intent...that the composer or musician is trying to convey in
the music that really gets through to us...but admittedly...this is a very difficult experience
to describe in words...and...it may be something one comes to later in ones musical life...

The B200's in Open Baffle is something very very special...may I refer you to the
post started by DMason on Red Wine Audio...Gravity Well of Dark Star for further
reading...anyone one who has not heard the B200's in Open Baffle can possibly
imagine what it does for music...and words are poor substitutes...however, let me
try to suggest what it sounds like with a highly refined and sophisticated amplifier
like Roger's 45 and 2A3 SET amplifiers...which sound to me like the very best in
the world...

It has the transparency of electrostatics...the penetration of panel speakers...the
dynamic drive of pistonic drivers...and it uses the backwave resonating in concert
with the front wave to create a 3-Dimensional soundscape that holds the music in
a suspension of air that surrounds you and infuses itself emotionally...

DMason's gift to anyone who has the enthusiasm and "esprit" to experiment with
new paradigms...

Warm Regards -Richard-


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« Reply #12 on: 16 Dec 2005, 09:39 pm »

Yes...you are right...yet again...Roger's subwoofer has allowed the B200's in OB
to reach new levels of spaciousness and an organic completeness that is staggering...
DMason has been telling me to get a sub for weeks...suggesting exactly what you
have just said...but I have been reluctant to get one for several reasons...not the least
of which is that most subs call attention to themselves...designed for home theater
films with their explosions and crashing dinosaur feet...

Roger's subwoofer with its own dedicated amp and his active crossover does 2 very
important things...in the case of my OB's...it cut off all frequencies below 200Hz from
his RM-245 SET amplifier and it cut off all frequencies below 200Hz from the B200's...
Roger used his subwoofer with its dedicated amp to generate the frequencies below

This took the stress off Roger's RM-245 SET amplifier to negotiate these lower
frequencies which allowed it to play with terrific dynamics when called for...
and it also took the stress off the B200's...
his subwoofer filled in beautifully and merged with the B200's seamlessly...

Roger did a great deal of experimenting while I was there with various adjustments to
the amp and subwoofer...so there where times when I heard only the subwoofer playing...
it sounded very delicate and nuanced...in fact it seemed impossible to believe that
something sounding that delicate could produce the organic effect it does with the
B200's...but as soon as the B200's were folded back into the sound field that organic
space returned...

This would not be anywhere as seamless a sound if the subwoofer was merely dialed
into the B200's without cutting off its lower frequencies, or the amps lower frequencies...

Warm Regards -Richard-


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« Reply #13 on: 17 Dec 2005, 12:03 am »
Hi Brad and miklorsmith,

It is a reasonable question to ask anyone who has heard both the B200 in Open Baffle,
and Louis Chochos's Aperiodic 8's in their beautiful cabinets, what the differences
in their sound are...relatively to one another...since both use the Visaton B200 drivers...

Let me say right away that I did not have the best amp for the A8's...

Roger's RM-10 MK2, or his RM-200, both push pull tube amps that have garnered rave
reviews...or Vinnie Rossi's Lotus digital amp with its exquisite clarity and resolving of
inner detail...would have had better synergy than my SEP integrated tube amp...

The reason I say this is because my SEP is too crude for the A8's...and so is my
Pioneer CD player...Vinnie knows my CD player very well  and thinks it is one of
the most digital sounding of the breed...

So as already mentioned, the B200 in OB is more forgiving and less detailed than
the stupendously detailed A8's...how detailed?

Think Maggies 3.6's on steroids!!!!

Recently, Lonewolf/Chris took pity on me...and out of his extreme generosity allowed
me to audition his A8's in my home...Thanks Chris for your kindness and friendship...
you are a gem...let no man knock our New York friends...hearts as big as King Kong!!!!

Deb and I sat there speechless...right away Deb said she could easily live with the
A8's forever...naturally they are extremely revealing of all upstream components...
like my amp and CD player...

Here is a speaker that will benefit enormously from highly refined components...
everything...EVERYTHING...on your CD is revealed...

Audio enthusiasts pay thousands and thousands of their hard earned money on
multi-driver speakers that do not even come close to the resolution and inner detail
that Louis's A8's reveal...no tweeter needed here...the highs sparkle like stars...

Electrostatic speed and extraordinary transparency...in their Aperiodic cabinets the
B200 changes its character somewhat from its OB personality...a little less warm...
and of course one does not hear that wrap-around penetrating di-pole sound that
the OB's do like no other speaker I have ever heard...

However, the A8's are the best single-driver, wide range speakers
I have ever heard in a cabinet!!!

Deborah's first words upon hearing them for the first time was "...there is no
boxiness to the sound...it sounds completely free of the cabinets..." a perfect
observation!!! The S8's sound like that are being transported into the room from
some unknown source...as if the musicians are invisible right before you...

Did I miss the OB sound when I was listening to the A8's? Actually, no. On some
recordings Deb and I sat there spellbound...really...the inner, inner, inner detail came
forth out of a black space and shimmered in the air...focus of voices and
instruments in space was surreal...

Lovely mid-range that allowed voices to present themselves whole and palpable...
Wait a minuet, Richard, that is what you said of the OB's...well, yes, we are talking
about the same driver after all...and the bass frequency was much tighter than what
the OB's can achieve...in its present incarnation at least...

As I said...Deb loved them...had I not had extensive experience with the B200's in OB
I would have ordered a pair...but when I switched back to the OB's...well...there is
something about the way they load the room that is...magical to me...more intimate...
a word some AC members told me they have trouble translating to sounds "real"
characteristics...perhaps I can suggest: very warm and moist sounding...sensual...

That is why I have ordered a pair of Louis's Super 3 Bipoles...Vinnie Rossi told me
he thinks they load the room in a similar way as the OB's...hummmmmmmm...
this I have to hear!!!!! Louis has assured us that his new Hemp drivers will be able
to replace the 4.5 inch Fostex drivers once they are available...perhaps 6 months away...
that does not seem like a long time to wait...

I have patience...It would probably take that long for the banana drivers of the
Super 3 BP to break in!!!!

I hope this helps somewhat to give you both some idea how they sound...

Let me know if I can help further...

Warm regards -Richard-

Russell Dawkins

Roger's sub(s)
« Reply #14 on: 17 Dec 2005, 12:06 am »
From what you are saying, it appears there was little or no discontinuity between the B200s and the sub. That is quite an accomplishment in itself - even more surprising, given the 200Hz crossover frequency and the fact that we're talkng about a mono sub, aren't we?
I would like to know more about the sub itself and whether two subs would take it up another notch.
I would also love to have heard the setup!


« Reply #15 on: 17 Dec 2005, 12:44 am »
Thanks so much, Richard.  As usual, your mastery of our colorful language leads the reader on spectacular journeys.  I can almost taste the wine. . .


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« Reply #16 on: 17 Dec 2005, 02:50 am »
Hi miklorsmith,

You are much too kind...thanks for your friendly and generous thoughts...
which reflect this very generous season where good will has a chance
to flourish...even for a little while...

Hi Russel Dawkins,

Yes...Roger was working with one subwoofer...barely larger than the driver
which I think was somewhere around 11 inches in diameter...I will get more
detailed information when I see Roger next week...he intends to apply some
science to my OB's to see what is going on there in measurable terms...

The driver enclosure was also thin...meaning barely deeper than the driver
and there was no port...

What made the whole thing work as well  as it did was the way Roger implemented
his active crossover unit...which seemed to use computer sound cards to create
the exact parameters the active crossover operated within...and the fact that he was
able to affect the frequency range of his RM-245 and the B200's together...so that the
amp he created to drive his subwoofer could take over reproducing those frequencies
and deliver them directly to his subwoofer...relieving the RM-245 and the
B200's of operating in that region...

The result was an astonishingly clean sound with tremendous dynamics!!!

Roger will have more to say about his subwoofer next time we meet...and it would
be great to see a photo of it up on his web site soon...

Roger feels in order for him to go into a modest production of his subwoofer/amp/
active crossover he needs a few orders to make it worthwhile...hummmmmm

I am hoping he will make one for me...I now feel lost without it!!!

Roger helped me to understand that it is not the B200's that are rolling off at
200Hz...at least not in absolute terms...it is the cancellation of the lower frequencies
as the back waves flow around the baffle to the front...it is therefore in a very real
sense the baffle itself that is rolling off at 200Hz...putting wings on the baffle should
compensate somewhat for this high roll off...perhaps adding as much as another
octave to what the B200's can smoothly reproduce...there is science going on here...
and Roger is helping me to see how we can use it to make the B200's in
OB even more effective!!!

I would think that 2 subwoofers would be even better...perhaps placed below the
B200 and integrated into the front panel...

Warm Regards -Richard-


« Reply #17 on: 17 Dec 2005, 03:22 am »

Thanks again for your eloquent description of your experience with the B200's and A8's.  You paint a vivid aural picture.  

I am probably going to try the B200's in OB first, since I have a pair of VMPS subs I can use with them.  My Scott 222 is 14-15 wpc and I think will do a good job of driving the B200's in OB.

With the A8's I think I could get by without subs - but I think I will probably use what I have - that way I can experiment with the B200's.  I can always ship the drivers to Louis to be installed in the A8 cabinets  :wink:


Vinnie R.

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« Reply #18 on: 17 Dec 2005, 04:08 am »
Hi Richard,

I just spotted this thread and really enjoyed reading it from start to finish....thanks for posting this!

The idea of a small, sealed sub that can keep up with the speed and articulation of the B200s is VERY interesting  :D    
If it can keep up with the B200s, it can keep up with my A8s and/or Super 3s, so I'll want one!  :hyper:  

Quote from: -Richard-
Roger feels in order for him to go into a modest production of his subwoofer/amp/
active crossover he needs a few orders to make it worthwhile...hummmmmm

Looks like you brought Roger over to the right place.  Perhaps this can be explored some more in the (near) future  :wink:  

I also enjoyed reading your observations of the B200 OBs vs. the Omega A8s.  

Nice discussion going on here.... I love it!



« Reply #19 on: 17 Dec 2005, 04:17 am »

Welcome to Audiocircles. If I'm understanding you correctly, you 'simply' conducted a gradient search of the surface of of various operating points with constraints of specific and overall dissapation, etc.... I'll also assume that your solution of this convex LP program yeilded some local minimas that actually sounds good. Nothing revolutionary, but rather an example of well executed engineering, which is equally rare.
While certainly of fan of dipoles (I've been using one for 350hz+ for the last 16yrs), I'm simply too dense to percieve anything approaching a new pair of dimes. But I do find the repeated use of the term 'organic' particularly apt as a descriptor of the purple prose.
That choice of a 200hz for woofer duties also has tremendous appeal, as it makes for a reasonable sized open baffle, limits hp driver excursions, and is amenable to room/bass correction (by digital, heaven forefend!) for that woofer subsystem.
Just one last question - Is the 6dj8 appropriate for audio use? :wink:

Looking forward to your continuing posts,