[fergs1]

Greetings everyone, a big thanks to everyone who has taken the time to help me, and in particular to Martin for his continued generosity to newbs like myself. I have a warm fuzzy feeling 
   This is a great forum and I for one am very greatful for its existence
                                     peace and goodwill   fergs

[Graham Maynard]

Hi Richard,

Please let me restart here by repeating you most important question, your findings, your suggestion, and your request.
I wish to address all.

So why am I tolerating a cross-overless overlapping of the B200's and Alpha-15A's from 175 Hz to 2500 Hz?
Because it sounds quite beautiful, fully-saturated, tonally rich and complex, an incredible bloom of sound that I now find terribly appealing... and Deb loves it as well... it is a "revelation".
So those of you that have the same set-up that I do... or something similar... take a walk on the wild side... take out the copper inductors and resistors and let your 8" and 15" play "full-range" without any filters and see what happens... at the very least you might get a sense of the real potential of Open Baffle design to free your music from the constraints of what we think we know... or have been told to think... and what is actually possible.
Please share your experiences here.
With Warmest Regards ~ Richard

Please permit me to backtrack to your original post.
Why does it (did it) sound better ?
1.  Direct connection without any series passive components between an amplifier and a driver ensures that voice coil drive voltage is an unmodified copy of the original waveform.
2.  Any components in series with a driver introduce phase shift and a group delay of some frequencies with respect to others heard.  Thus even a simple choke will be introducing phase lag to the Alpha waveform with respect to the B200 drive;  the lower the crossover frequency, the lower the frequency at which the lag becomes dominant.

You appear to have empirically determined a compromise, but you still have a choke, so I am left wondering whether some of the direct connection 'magic' has been sacrificed.

I too am running the B200.  It is a very fast driver, and thus it is hard to integrate another driver such that voices and instruments reproduce with convincing integrity as opposed to having to accept a compromise in order to build out their fullness.

Your present choke must already be detracting from what the Alpha is capable of on its own.
Solution ?
Simple.
Mount the driver on the front of the baffle pointing backwards.  Reverse the connections to its terminals and drive it directly from the amplifier.  Also place some very soft damping material on the Alphas axis about the same size as the magnet and about six inches behind the baffle.

Facing the Alpha the other way provides a 'mechanical' crossover without the disadvantage of its output becoming increasingly lagging through some series choke induced turnover range of frequencies.  Any rearward beaming peak circa 2kHz will be well damped and delayed beyond the recognition range of front B200 radiation.  There will be no copper wire electrical losses due to a choke.

Why am I saying 'will' with such a degree of certainty - because, as you requested, I am sharing my experiences - I have just done this with my own baffle. 

Back in the days when I helped my son with car subs I often had drivers facing into cabinets;  it is like having a 'cost free' 6dB/oct crossover without energy losses, with that extra damping material ahead of the cone always seeming like yet another 6dB/oct.

Also, with the 15" cone now being in front of the baffle, it has a fractional 'head start' to better match the faster B200 in generating wavefronts at frequencies where both drivers are expected to work together.

This is most definitely worth a try. 
Simply reverse the driver on the baffle so that it sticks outwards from the front, reverse the electrical connections, remove all chokes to provide direct drive, and loosely roll up some soft clothing behind the baffle.
To heck with the looks if it works - Debs might be able to make you a fine cloth grille if the arrangement turns out to be a keeper.

Cheers ........ Graham.

[chakija]

I am sorry for bringing this thread up ,but i had to share my findings which are connected with subject in this thread.
I am too happy owner of Alphas ,and i had them playing along with alpha 6" and selenium st324 for a while.Crossing 6" and tweet was real PiA but i finally menage to arrange it with st324 with crossover from bottlehead forum.With it's crossover st324 plays very linear and clean down to 3.5KHz after which naturally falls 24db/oct.Alpha 15" played with 6,7mH choke.
Recently i sold my alpha 6" and decided to play 15" FR with st324 until my new monacor FR arrive.
Surprisingly ,sound was still quite nice ,with lacking of mid dynamics but overall with smooth and rich tonality.High tones are improved too ,bass less slimy ,it is smoother...However ,on some tracks i get that ear piercing mid but i think i could live with it  .
Here's a picture of current U baffle. 
First thing i am planning to do is nearing drivers next to each other to get better blending ?!?
I wanted to ask ,how far from floor Alpha is allowed to be ,so it could still play low enough ?

[Graham Maynard]

Hi chakija,

Try connecting a 4.7uF capacitor across the choke terminals you have in series with your 15" driver, might tame the mid peak.

Also, if your crossover is single choke only you could do with a Zobel of say 6.8 ohms (try 4.7 to 10 ohms) in series with 4.7uf connected across the Alpha 15" terminals.

Cheers ....... Graham.

[BrassEar]

I must thank Richard for this thread. 

I have been working on some Emerald Physics clones which use 2 x Alpha 15s + waveguide and compression driver. I am generally very pleased but still not too thrilled with the Behringer DCX2496 digital xover and EQ. My experience with this unit reminded me of a Meyer quote "EQ is like pushing Jello around." Even with TrueRTA setup I had a very hard time getting the sound I wanted and I don't like the noise when using a super high sensitivity compression driver with the Behringer.

After recalling this thread I removed the active xover and played the 2x Alphas FULL RANGE and threw a small cap on the compression driver.  WOW! Although I measured and saw a major 2 Khz peak (the natural Alpha peak)  with some tweeter overlap, it still sounded better than I could ever get it to sound with the DCX crossover/EQ.

Next step was to put a proper coil in series with the Alpha twins to roll them off first order around 1K. Ditto the cap for the compression driver around 1.5K.  Right there the sound was so good that I have no desire to change things as everything sounds so right, so LIVE. When a system sounds this LIVE, you forget about all of the audiophool tripe like transparency, imaging, depth, etc. as you just marvel at the musicians in your room.

I know the xover is not technically "right" but right now I don't care. It also measures pretty flat except for the expected OB roll off. I plan on getting a trio of small subs ala Geddes to fill out the bottom end.

It's funny after being in this hobby for over 30 years, I had to break all of the audiophile rules to get the best sound (cheap 15 inch drivers running up to 1Khz, horn loaded compression driver down to 1K, one pro amp driving the woofers, etc. These DIY OBs sound better than all of the expensive audiophile speakers I have owned over the years.

Bottom line - don't be afraid to run those Alphas much higher in frequency than previously thought possible. 

[mcgsxr]

Congrats on your discovery, and thanks for sharing.

It IS a lot of fun to break the rules!

[nvrgdenuf]

Interesting reading on this thread. I have two Alpha 15,s and two more on the way along with waveguides. I tried a fullrange driver with the Alphas as I mentioned in another thread, but it sounded thin. Maybe raising the low pass would have helped.
Since then I have been reading the BrassEar thread on his clones, looking forward to his latest comments about tweaking these badboys. I have to wait to get mine setup, but it will be my first run with the dcx 24/96. It made me think to just start with simple x-over fq's and slopes listening for the best synergy,(as what might have attracted Richard), would be the best route. Maybe throw in phase correction, but leave out the eq'ing and filters, and work one area at a time not necessarily chasing the flat fr line. A House Curve could certainly be more appealing with a midbass hump than a flat line.
BrassEar keep me informed of your progress please, on your thread of course.
Richard sorry for the off topic a little, but heck you might not even read this old thread. But thanks for sharing your experience with your OB setup.
Cheers

[JohnCZ]

Richard,
It was at your advise that I built my B200 OBs. They were about 40" h with two hinged wings. I lived with them for about a year and set them aside to build a different design. I guess I was missing something with them and was itching to try something different. With all the talk about the Alpha 15s, I decided to pick up a pair and rebuild the B200 OB.  I built a slightly smaller baffle with the Visations - 17x40, to include the Alpha 15s.  Just as I was about to wire the drivers I read you "Going beyond HiFi" topic and decided to just run them without the filters.  I too was amazed at the sound  compared to the original single B200 OB.  Friends that heard them were also amazed - they were very musical indeed.
 
However, I do have one comment about them regarding low end dynamics.  There is substantial low end information.  The Alphas really support the B200s.  But, I do not have any leading edge dynamics to the bass.  For example, percussive sounds from a tympany sound as if they were off stage, yet the reverbation of the tympany is room filling.  A perfect example is the end of the first movement in Mahlers First Symphony.  Other leading edge bass transients seem to be missing, yet the Alpha gives the piano more realism - its more fleshed out and full.

Both the B200 and the Alpha are connected in polarity + to +.  I also installed the filters - the resistor and 6.8 cap to the B200 and a 4.7 inductor to the Alpha and the results are the same.  On most non-dynamic music they are musically excellent and do not seem to missing anything.

My next thought was to use a subwofer plate amp just on the Alphas. I would love to hear if anyone else has experienced this.  John

[Graham Maynard]

Hi John,

This is something I have been warning about for some time, it is the high Qes of the Alpha that does it, and changing the amplifier won't help.

The best way to overcome the lack of dynamic attack during the leading edge of a LF note is to implement the transformer bass (T-bass) circuit which can be tuned to phase coherently increase the first half cycle (percussion) amplitude with respect to the continuing (sustain) waveform.

Cheers --------Graham.

[-Richard-]

Hi John ~

Thanks for sharing your exploration with us using the B200's and Alpha 15's in your new OB configuration. I applaud your willingness to work with a (relatively) simple Open Baffle design to see what you can learn from it.

Your listening skills have a great deal of precision:

"But, I do not have any leading edge dynamics to the bass.  For example, percussive sounds from a tympani sound as if they were off stage, yet the reverberation of the tympani is room filling.  A perfect example is the end of the first movement in Mahler's First Symphony.  Other leading edge bass transients seem to be missing, yet the Alpha gives the piano more realism - its more fleshed out and full."

I am using a simple coiled inductor from Parts Express on the Alpha's... the little sticky label that came stuck to it has a value of .80... the inductor cuts off the Alpha's at around 1200 to 1300 Hz (check with a techie at PE to make sure the value is correct). I chose that cut-off point based on the wave chart of the Alpha's that was published on AC that showed a peaky rise in the Alpha's above that.

The B200's and Alpha's are hooked up in parallel (the negative wire from the B200's bypasses the inductor... like you said "+ to +" only).

Also I purchased the super-fast cheapo cables that Jeff Day recommended many months ago and use them only for the Alpha's (B200 to inductor... Alpha to inductor): Yard Master Patio cord.

http://www.6moons.com/audioreviews/whitelightning/moonshine.html

How fast is the cheapo YMP cord? lightning fast... you may find that the "leading transient edge" of the musical information rendered by the Alpha's entirely present... at least I do.

Using the simple coiled inductors and YMP cord for the Alpha's (and super-cheap Lowe's copper-cable for the B200's) the sound I get is completely integrated, musical in the extreme and as "detailed" as the music needs to render an expressive, highly textured and nuanced musical life.

Those are the facts... now let me drift sideways just a bit and allow myself to ruminate more intuitively on your important insights and observations. It is entirely possible that your listening skills are more precise than mine or that your room and mine may favor certain frequency gamuts (or suppress them) due to absorption or reflection issues. Here is another observation, each speaker paradigm renders certain musical forms differently (instrumentation, voice/s, complexity, recording venue, the engineer's fiddling with the recording, the microphones used and their placement and so on) and more or less favors some musical forms over others.

It may be that no single speaker design can render all musical forms in the way that we would like... or in the way we think we hear things during the live event (assuming the music is not amplified during the event). So does that mean that we need to have more than one kind of speaker in our music room and choose between them according to how well they render a particular kind of music? I just have my OB's and Deborah and I love them... I mean we really love them for every kind of music and we have had many kinds of speakers over the years... including the experience of dragging poor Deb from one audio shop to another during the early periods of learning how to listen to music as it was reproduced by various speakers... Deb loves music perhaps even more than I do.

Perhaps I inwardly compensate for the shortcomings of my OB's... or perhaps I am so happy with what it does do well that I can easily forgive what it may not do as well... or perhaps I am so thrilled with the dynamic snap and sweep and un-congested un-boxed and open as-if-it-was live sound of the OB's that every other consideration seems irrelevant to me... that in-the-room palpable holistic immediacy and connection we make with the instruments and voices seems to bring about that aesthetic jolt... that emotional connectedness... that speaker designers kill themselves to try to emulate... and never actually do... and for larger and larger sums of money thrown at basically inadequate technologies.

I purchased an amp that sounds so good with my OB's that I feel that for me I have reached the end of my explorations into musical bliss... the on off switch broke and I sent it to Canada for repairs... I am patiently waiting for it to be sent back to me and I will write about what it sounds like with my OB's in more detail... but to say it has synergy is simply not strong enough of a description.

Again... thanks John for sharing your observation and insights with us. Please keep us informed of your on-going explorations.

And please let me wish all of our AC community the Greatest Happiness Imaginable in this New Year... Deb and I have almost no money coming in (publishing... like almost every "industry" in this country is temporarily in contraction) but we are re-evaluating everything in our lives in order to adjust to the depressed economy. One great thing is that Deb is not working right now... and so we have lots of time to enjoy each others company... which we really love. That is the greatest thing for us about the current "depression" we are all muddling through... more time to enjoy the simple pleasures of life. I am being entirely serious here.

And this is one very important reason for everyone that needs new speakers... or would just like to experiment for themselves to learn something new about musical "perception"... to stay on the really cheap side of things by building their own OB's for a fraction of what "commercial" speakers cost... and... your musical experience will actually take a giant leap toward the "real"... once there... you may never go back again to the boxed-in sound of what doctor Dan Mason used to call "monkey coffins".

With Warmest Regards ~ Richard

[Arlo]

Yes I will backtrack to the original post too.  I also did this with the alphas and it sounded good.  I eventually put the coil back on because there was too much output above 1khz (as some of you have described) just before it rolls off.  I found the area from around 250 to 500hz was well done by the Alphas.  Alas, I concluded that they are far too slow and mushy (syrupy? ) for actual bass duties.

[JohnCZ]

Hi John,

This is something I have been warning about for some time, it is the high Qes of the Alpha that does it, and changing the amplifier won't help.

The best way to overcome the lack of dynamic attack during the leading edge of a LF note is to implement the transformer bass (T-bass) circuit which can be tuned to phase coherently increase the first half cycle (percussion) amplitude with respect to the continuing (sustain) waveform.

Cheers --------Graham.

Graham,
I understand that this was the problem but could not describe it as technically as you did. The part I dont understand is the process.  Could you describe how I would develop a t-bass circuit?  Or, would it be easier to use a separate amp (plate) or just use another driver. 

I've heard a couple of versions of Nelson Pass' open baffle designs at the Rocky Mountain Audio Show the last couple of years and his design had great impact. He used the Tone Tubby 10 inch bass driver (this year) and last year used a Seas driver.

Richard,
Thank you for your comments.  I too am very pleased with my OBs in general. I probably would not notice what I described had I not been familiar with the music (having performed with musical ensembles in the past).  I'll try some simple upgrades suchas your suggestion of hookup wire. I also agree that some speakers create a synergy with their enviornment.  My listening area is not the best for Open Baffles - it is somewhat space restricted.  Even so, the B200s are fast and revealing, the soundstage is large and they are very musical. 

John

[ttan98]

[/quote]

Graham,
I understand that this was the problem but could not describe it as technically as you did. The part I dont understand is the process.  Could you describe how I would develop a t-bass circuit?  Or, would it be easier to use a separate amp (plate) or just use another driver. 

I've heard a couple of versions of Nelson Pass' open baffle designs at the Rocky Mountain Audio Show the last couple of years and his design had great impact. He used the Tone Tubby 10 inch bass driver (this year) and last year used a Seas driver.



John
[/quote]

How do you compare the Tone Tubby 10" bass driver with the Seas? These 2 drivers have very different characteristics, if possible can you describe them if you can remember thanks.

[opnly bafld]

How do you compare the Tone Tubby 10" bass driver with the Seas? These 2 drivers have very different characteristics, if possible can you describe them if you can remember thanks.

The TTs were only going down to @70hz and they were using a $150 sub from 70hz down.

Lin

[ttan98]

How do you compare the Tone Tubby 10" bass driver with the Seas? These 2 drivers have very different characteristics, if possible can you describe them if you can remember thanks.

The TTs were only going down to @70hz and they were using a $150 sub from 70hz down.

Lin

Thanks for the response, the TT drivers must sound pretty good otherwise Nelson Pass would not have used them. I am thniking of using them in a cabinet instead of OB. Even if I use them as OB I need a subwoofer or a sealed bass/ported 12" woofer cabinet.

[JohnCZ]

ttan98,
If I remember correctly, Nelson used the PM6A the last two years or so.  Last year when he used the Seas drivers they sounded very fast but a little lean.  Transients were very good and kept up with the Lowther.  It seemed as though his filter/crossover was a little steep or maybe a bit low with the Seas design. With the Tone Tubby there was more upper bass. The foundation was more substantial.  I liked the Seas and thought it was a good match with the Lowther.  The Tone Tubby was a substantial step up in bass.  It sounded more at home in an open baffle than the Seas did.  After hearing the Seas design I wanted to try and build an open baffle to see what I could do. Upon hearing the Tone Tubby version, I wanted to buy Nelsons speaker.
John

[-Richard-]

Hi John ~

I am very glad to hear that you are a serious musician... I suspect there are not many audio enthusiasts that actually have your level of highly developed musical skills... and it confirms my suggestion that your listening skills are extraordinarily sensitive.

I built my own clavichord from a kit offered by the Zuckermann Harpsichord company many many years ago... I also learned to weight the keys and tune it, using several tuning strategies including counting the beats of various harmonic pairings of strings. Playing my Clavichord gave me a rare pleasure and taught me how to listen sensitively.

There are several audio writers that claim that the speakers they use come very close to the real thing... for example Robert Green feels that his expensive Harbeth's come very close... he plays the violin and teaches audio math in California. I like Harbeth speakers but I gave them a careful audition less than a year ago and there was no comparison to my own OB's... actually I was amazed how artificial they sounded in comparison... Deb found them constrained and compressed sounding by comparison (Deb is not an audiophile but she does listen sensitively). When I pointed out to the salesman what I was hearing... an old-time Harbeth dealer and a nice guy... he responded... "yes... you are hearing the box." He knew.

What I have found over the years is that audio can create an alternate or parallel sound field that replicates, within its limitations, the real thing... audio can potentially have a similar gestalt... a similar sense of wholeness... as if the fundamental tonal and textural character is complete... which is of course an illusion... in fact, audio does not even come close. But that is not important... it is the ability of audio to replicate that sense of wholeness... of completeness... that makes it so deeply satisfying. But it is limited.

How limited? That is the important question for anyone interested in having a deeply satisfying musical experience with reproduced sound. What I look for in my "audio" experience is that all the elements come together to create the illusion that what I am hearing is not reproduced... is no longer a mechanical xerox that is essentially dead and that I must somehow reinvigorate with my imagination. I want to be convinced enough that what I am hearing is "live" and "spontaneous".

For me... my OB speakers with my ancillary equipment comes the closest to that kind of experience.

With Warmest Regards ~ Richard

[panomaniac]

And there you go , John.  Tastes are different.  I liked the rig with the 2 tens better.  The Tone Tubby was good, but the 2x10 was much more to my liking. (were they Seas?)

I may agree that the TT matched in tone a little better with the Lowther, but the Seas sounded much cleaner to me.

Of course, there was a year between listening sessions, so take that with a grain of salt!

[ttan98]

I may agree that the TT matched in tone a little better with the Lowther, but the Seas sounded much cleaner to me.

I suspect Sea sounds cleaner is because Seas has much lower distortion than TT, I think TT gives you more body to the sound. It is all a matter of taste as you say. I personally prefer the drivers that give me more body/rounder sound, compared to a leaner/cleaner sound from Seas.

[opnly bafld]

2007   Seas W26


2008  Tone Tubby and crappy sub