[opnly bafld]

scorpion,
I first tried a Hawthorne Audio Augie 15" bass driver made for OB/IB bass.
Was having good results, but the big 15"er was shaking the baffle quite a bit.
Then I read Dmason was having good results with 2 B200s.
I decided to give it a try and am glad I did
In my good sized room, the response is -3db @40hz and +3db @50 compared to 1k with two drivers, the lower one x-over @80hz 6db/oct.

I am going to try the Augie on separate baffles playing somewhere between @60hz -100hz and down. (electronic x-o)
With the Visatons high passed to see/hear what happens.

As far as using the same driver, I would not think this would be necessary in every case.
A lot would probably depend on the x-over point and slope, quality of each driver and so forth.

The B200s can actually use the added upper bass frequencies that result from a 6db slope since it has a tilted up response.

Lin

[Wind Chaser]

Lin,

Are you using any EQ, tone controls or loudness compensation?  What amp are you using?  Man, I'd be happy to get -3db @ 120Hz!  Maybe my B200's are not the same as yours?

John.

[opnly bafld]

My baffles are 45"h x 20"w.
I have 2 B200s on each baffle, the lower one is about 5" off the floor.
They are biamped with a Monarchy Audio SE160 tube/fet on top and an Eagle 2 SS on the bottom.
No EQ of any kind, other than the ability to turn the lower driver up or down.
I used a Rat Shack SPL meter, 2 meters from the right speaker, with test signals that are supposed to be adjusted for its inaccuracies.
My ears bear these numbers out, I have several speakers that go to 40hz or below and the OBs have, subjectively, just as much bass as the others at moderate listening levels.

Lin

[scorpion]

Lin,

I have also played around with my RS Spl-meter.
Things were as I explained in my earlier post only that I put 9.2 mH i series with the left hand speaker to restrict the 6 db filter to 100 Hz.

I measured in the stereo seat 2.5 meters from the speakers.

Calibration was to 85 dbC at 1000 Hz both speakers playing a mono signal.

My measurments were as follows:

First column is frquency, second with only right hand speaker playing fullrange, third column with both speakers playing.



20  , -   ,  55 dbC
25  , -   ,  57
32  , 57 ,  62
40  , 70 ,  75
50  , 74 ,  81
63  , 73 ,  81
80  , 83 ,  88
100, 72 ,  77
125, 78 ,  84
160, 77 ,  86
200, 76 ,  82
250, 82 ,  82
315, 85 ,  86
400, 83 ,  85
500, 88 ,  88
630, 83 ,  83
800, 82 ,  82
1000,85,   85

That's it. For what it is worth ! There is a narrowbanded cancellation in my room at 100 Hz. Good SPL excists at floorlevel and a bit up but falls
at normal sitting and standing heights.

/Erling

[mcgsxr]

http://cgi.ebay.ca/JVC-EX-A1-Compact-DVD-Audio-Video-System_W0QQitemZ9733568759QQcategoryZ1499QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The most synergistic match with the b200 that I have heard to date.

Not mine, just an opportunity to check one out, cheap!

[Wind Chaser]

Mark,

Does this unit have a Tripath chip?  What other amps have you tried and in what sense was the JVC better?  In the last few months I acquired a Jungson integrated amp that sounds decent and a couple of Charlize modules that are most impressive.  I haven't heard either of them with the B200 as my drivers are at Planet 10 and I don't expect them back till the late June.

Prior to sending the B200s out for modification, I put over 300 hours on them with a Sony mini system similar to the JVC.  The Sony has what they call a "Dynamic Bass Feedback" circuit, which essentially is a loudness switch that increases the bass.  Using that feature with a little EQ I was able to achieve a nice balanced sound from top to bottom on the B200.  Are you using any EQ from the JVC to bring up the bass?  Thanks,

John

[opnly bafld]

Hey Mark,
How is your coffee table coming along?
If you have milk and sugar with your coffee or tea, it will be shaken, not stirred.

Lin

[opnly bafld]

As I was listening to Donald Fagen-Morph the Cat tonight, yes the Bs x 2 have BASS, I thought about (with the help of some friends ideas ) what could possibly be an ultimate all B200 OB speaker.

top driver running highpass @80hz- 24dB slope
middle driver lowpass @80hz- 6dB slope
bottom driver lowpass @80 hz- 24dB slope
Of course, you could use 2 bottom drivers, if you just happened to have 4 pairs lying about.
Lin

[scorpion]

Nice to see a reminder that we are just playing around with toys !  

/Erling

[mcgsxr]

Lin - the table progress has stalled, and is likely to remain static as is, as I research the pros and cons of U vs H baffles.  The sound it creates today is acceptable, and since it is in my "dedicated" listening room in the basement, there is little motivation to finish it cosmetically - heck, my open baffles are still raw mdf after 12 months...  Once I sort out what next steps to take, I will find the time between work, kids, and vacation, to do a little more.

As for the baby JVC, well it does not use a TI chip, or Tripath chip at all - it is the Hyrid Digital technology that JVC uses in their receivers - the EX-1, the FS-10, and the current 7 channel versions - this is just a 2 channel implementation of that tech - it is also their "ultimate" version of that technology from last year - if you Google the EX A1, it was their "Sony ES" model with copper screws, much attention to detail around the components and layout etc.  A solid little 2x30wpc performer.

I have tried the following amps with my OB b200 creations:

JVC EX-1 - 5 channel receiver, my introduction to Hybrid Digital -amplification from JVC - sold to best friend
Panasonic XR-25 - still own, in main floor HT system
Panasonic XR-55 - returned to Best Buy, no significant difference from XR25
Stock Teac A-700LP - eventually modded
Teac A-700LP with Vinnie mods to power supply - not his Red Wine Audio DC version, an earlier exploration on his part, into upgrading the PS in the Teac - sold to beatdownvictim on AC
Bolder Teac A-700LP - also found its' way to beatdownvictim on AC
Custom Gainclone LM3875 dual mono - still own
MarkC's custom, hybrid monoblock tube/fet creations - could not afford

OK, truth be told, the best I have EVER heard were MarkC's amps, but the financial outlay at this time, is not for me.  Those amps did things with my speakers and front end, that absolutely stopped all of us in the room.  I have raved about them in PM's to some folks, they are stupendous.

So, the most equitable solution of those listed, outside the monoblocks, is by far the JVC EX A1.  I know that nodiak has one, and thinks it is OK with the b200, but has a different room than mine, so that could be highlighting some issues, that mine does not.

Simple little guy, with a useful sub out, to help with the bass augmentation process...

I paid around $265 shipped off eBay, and it remains the best suited amp to my b200's - it fleshs out the mid-bass and below.

When using it running full range without the sub, I tend to use +1 on the bass.  That alone is good enough for 85% of my music.  The remaining 15% needs the sub, so I back out the bass +1, and turn on the coffee table!

It does not have, nor do I use, a loudness function - it really does not need one.  All the other amps by comparison (MarkC's aside) sound reedy, and way too trebly for me - they exhibit what the FR of the raw b200 looks like.

For some reason, the EX A1 (perhaps since it was designed from the ground up for use with single drivers, as it comes with some sake soaked, wooden coned speakers) just plain mates perfectly, and sounds good.

Cheap, cheerful, simple, and with a sub out!   Now, if I could only get the volume control out of the way, and run my Bolder SB3 AS the preamp....

[Wind Chaser]

I placed a coil inductor with a cut-off at 100 Hz with a 6 db per octave augmentation
between my upper B200 driver and my bottom B200 driver...

The result is astounding bass...just as Dmason suggested...

Richard,

Where did you acquire this coil inductor and what are the values?  I'd like to order a pair of these too as I now have a second pair of B200s on the way to help flesh out the bass so the 15" Augies can be crossed over at a lower point.  Having 2 Charlize amplifiers I was thinking of mounting one on each baffle to bi amp.

John

[-Richard-]

Hi Windchaser,

I am currently using a Jantzen 10.00mH 18 gauge Air Core Inductor from Parts
Express: model number 255-294:

http://www.partsexpress.com/webpage.cfm?DID=7&WebPage_ID=3&Start=4&Filter=Jantzen%2Binductors&searchorderby=1&sm=1&so=1&search_type=main&desc=ASC

Price is currently: $14.81  you will need 2 of course, 1 for each OB panel~

They also make a 15 Gauge model: part number 255-448  the price is hefty
however at $26.76.  Roger Modjeski likes larger gauges in this application...as least
as a theoretical standard...however I do not think we could necessarily hear the
difference...Roger did say that he thought 18 gauge was fine...

http://www.partsexpress.com/webpage.cfm?DID=7&WebPage_ID=3&Start=5&Filter=Jantzen%2Binductors&searchorderby=1&sm=1&so=1&search_type=main&desc=ASC

Roger did the math and yes...10mH is the correct number for a 100Hz cut off
with a 6db reduction per octave which should fold in frequencies up to 1000Hz...

I will be trying an Air Core inductor that cuts off at around 300Hz...which results in
3.6mH...I am interested to see what effect that has on the all-over sound...

This morning I went back to playing just the top B200...the difference was
startling...the entire bottom dropped out of the music...the fully fleshed out
dimensionality that I have been enjoying all but disappeared...I immediately missed
it and it did not take long to place the bottom B200 back into the mix~

Here is the way I was told to connect the cable wires using the inductor:
one set of wires go from the bottom B200 to the inductor...the other set of
wires go from the inductor to the top B200 driver. The positive leads from both
cable wires are attached to both prongs of the copper coil inductor...
while the neutral wires are tied together~

Let us know how things sound once you have things set up, Windchaser.
I think you will be amazed at the fullness and added dimensionality of the
musical presentation...if your amp can generate clean low frequency information
your dual B200 OB's will deliver!!!

Warm Regards ~Richard~

[corloc]

As of last Monday I have been running a pair of these in OB.

http://stores.channeladvisor.com/musicsupplycenter/Items/100-01-0186?

I can now see way a second B200 a side would sound great.  Now that I have about 20hrs on them and  point souce is dead on, but the imaging  dosent have the spooky 3D imaging, and I'm still tweeking the baffles.  I have them tied in passively with 5mH coils.  ABout 200hz.

The mids have definatly filled out and my ears are no longer searching to here the bass.  I have no problem with bass at least to 40hz. The drivers are decently made, and at $75 for both shipped I couldn't beat the price.

I'm very happy with them, but I want to get at least a hundred hrs.  on them before I give my opinion of sound.

Chris

[Wind Chaser]

Richard,

Thank you for the clear and detailed explanation.  I’ll order a pair of 10.00mH and a pair with somewhat smaller values to experiment.  Hopefully by the end of the month I should have all my drivers back.  My plan is to mount a Charlize on each baffle using one channel to power the top driver and the other channel to power the bottom driver.  This will effectively eliminate any cross talk and the need for speaker cables and thus become more of an active system per se.

Perhaps adding a U baffle in the form of a 10” length of Sono Tube to the bottom B200 will help maximize the effectiveness of the bottom driver?  As my baffles are 1” thick, there is plenty of depth to route out a groove to which the Sono Tube can dock into.  I will give this a try.

The 15” Augies will now have to go into a separate baffle and sit adjacent to the active panels.  This shouldn’t be a problem, as the active system can be quite narrow.


Chris,

Those look like great drivers and the price is right!  Have you got them mounted on the same baffle as your B200s?


John

[scorpion]

Wind Chaser,

I would advise against a fixed U-baffle. There will be resonances in 200-300 Hz area. I would much more fix wings with 5-10 degrees difference comparing with the plain 90 degrees. But it should also be good to add some surface above the lower drivers. It should be a good practise to avoid unnecessary resonances.  

/Erling

[smithereenys]

mcgsxr and dmason - i sent you a pm on jvc executive units

[Wind Chaser]

Wind Chaser,

I would advise against a fixed U-baffle. There will be resonances in 200-300 Hz area. I would much more fix wings with 5-10 degrees difference comparing with the plain 90 degrees. But it should also be good to add some surface above the lower drivers. It should be a good practise to avoid unnecessary resonances.  

/Erling

I had zero interest in OBs until I was introduced to the concept of the U.  The U baffle appeals to me because it negates the need for big imposing baffles.  I have read here and else where about the concerns with wings, how there are tremendous forces acting on them and if not properly and rigorously braced, they become problematic.  I already have Sono Tube cut to a variety of lengths.  The plan is to have them friction fitted so they can be quickly changed with various lengths or removed entirely.  At this point I'm thinking of making the baffles 12" wide by 42" tall.  The lower driver would be position 5" from the bottom and the upper driver would be positioned 5" from the top.

John

[-Richard-]

Hi John/Wind Chaser,

sounds very interesting...I like your enthusiasm and creative approach~

Please post pictures of what you put together...I have a feeling you could wind
up with a world-class OB speaker tuned to closely meet your expectations~

Thanks for sharing your thinking with us~

One thought...Vinnie Rossi's new OB's have the top driver quite a distance from
the top of his 48" drivers...he feels that positioning the top driver a bit lower
helps delay the signal from coming over the top too quickly which could lead
to cancellation issues...my baffle is 42" tall and my top driver is now 7" from the
top...however I am not familiar with any of the physical laws that are really at
play here...so I cannot confirm if lowering the top driver a bit will really make an
audible difference in real terms~

Please keep us informed of your progress~

Warm Regards ~Richard~

[Vinnie R.]

All,

Here is a pic of my new OB prototype:



JohninCR and I traded some PMs and he convinced me that going with just a wider flat baffle (I was using a 42" x 24" acrylic baffle before) might not give best results.  All I can say is that I am SO GLAD that I listened to him!  Thank you, John!

I had Louis cut the 3/4" MDF for me for this prototype.  The height is 48" and the center of the driver is about 30" from the floor.
The front baffle is 10" wide.  As JohninCR explained, the idea here is to start the wings as close to the driver as possible so they act as a wave guide for the back wave.  In this configuration, the back wave doesn't smack into them so the vibration of the wings is very, very minimal.  This made a lot of sense to me.  Since the B200 is centered left-to-right on the front baffle, the offsetting is done with one wing is 12" and the other at 13.5".  

Temporarily the wings are attached with duct tape along the seams (which is actually doing a decent job supporting everything!).  I have the angle somewhere around 30 to 45 degrees.  

My OBs are about 4 feet from the back wall.  The adjustable wings really allowed me to fine tune the OBs for my room....I LOVE IT!

How do they sound?  I am obtaining the best sound I've ever owned.  They do things that I have heard no other speaker do before.  The "reach out and touch the performer on the stage" effect is there in spades....such realism I have never heard like this before. The center image is soooo good, and the soundstage is very wide and deep.  These OBs make my recording sound like they are being performed in a live venue rather than being recording in a studio.  Playing these OBs I always feel like there are real performers on the stage in front of me, and the stage is well layered.  The top end is detailed and addictive and does not exhibit any traits of being overly analytical.  I have absolutley NO issues with beaming to speak of.  Did I mention that I am getting good bass response....fast, controlled, and surprisingly deep.  It begins to roll off below 80Hz, but the roll of is a slow roll off.  When using test tones, there is still bass in the 40Hz range for sure.  The amount of quality bass is surprising and I'm sure room gain is a big help here.  I am very hooked to what Dmason has dubbed as "audio crack!"  

Looking ahead, I am going to have to try the 2nd B200 in the baffle.  Dmason, Richard, and others here swear by it and I am very excited to give it a try.  It is kind of hard for me to imagine it getting better.  I can live with these for a very long time.  I'll report back once I try it!

After I finalize things and decide if I will be keeping the 2nd B200, I'll be off to visit Louis and he will make me a finished pair.  I'll have to choose the finish and final dimensions.  I really wonder how a finished baffle will sound.  Louis uses vaneer with a phenolic backing and I know how good this makes his speaker cabinets sound, so who knows what it will do for the baffles.  And with the 2nd B200 adding some more bass, I may be able to get away with a slightly shorter baffle and slightly less deep wings.  

Thank you to everyone who has contributed and continues to contribute to this Darkstar thread.  I'm not even sure if Dmason himself knew how strong the pull of the Gravity Well would be when he started this thread and I am beyond grateful that he did so!  

Happy OB'ing,

[Dmason]

Vinnie

You are in a perfect position to really test the 2X aspect of this design. If it works great. If not, great. It may be that in your audio only room with carpet, one driver is ideal. Have you tried turning your baffles upside down? Lowering placement of the single point...a final baffle by Louis is a good thing. I would like to see good bass with a scaled down overall profile. One reason the DarkStars sound so good appears to be totally accidental: the narrow static baffle and back-folding wings. The wings could be folded completely back and out of the way, in smaller rooms. Folded out for dedicated listening. Now I understand why they sounded best folded back at acute angles, and that vibration was never, ever an issue, despite dire warnings from the resident theorists, and pedants.

I have to add that the arrival of the Signature 30 pretty much ramps the whole DarkStar phenom into a new stratum. More juice, better by far, sound, driver control, really completes the picture. Having more power makes DSP contouring far better an option, especially in terms of lifting the lower register FR of the B200...This combination of driver/load/amplification is amazing destination audio. Anti hi fi. Just the music.