[ttan98]

I thought I will share with fellow OB builders on what I have found experimenting with a no. of OB configurations.

1. Full range(FR) and U frame woofer
   a. FE167E (FR)
   b. Hemp cone (FR)
2. MTM and U frame woofer
   c. SEAS OEM paper cone mid and dome tweeters (MTM)
   d. GRresearch M130 and B&C compression drivers and horns(MTM)

At this stage I am finalising my mid and high freq first as my woofers are of inferior quality and will be upgraded later.

The last option d. gives me the sound that I like the best, large sound stage, very open, very efficient(95-96dB) and very dynamic. I am using active x-over, DCX 2496 and possibly would be able to use passive components if I decide to at a later stage.

The option d. combo is very cost effective the total price for 4 mid drivers and 2 compression drivers and horns are only about US$220  not including postage. All these parts can be obtained in the States. I like to attach photos not sure how to, can someone explain, thanks.

Those interested in the details of components used leave a message. I will response.

cheers.

[ttan98]

I will provide some details on the mid range, compression driver and horn.

go to GRRearch website and look for drivers look under M130 model for 8 ohms, 2 in parallel gives about 95-96dB(I measured). These drives are very good, better and cheaper than Seas paper cone drivers. Each costs about $25.

Compression Driver and Horn go to Parts Express:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-600

and

http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=294-618

any other info you need let me know.

[ttan98]

sorry GRReach means GR Research.

http://www.gr-research.com/

[wikin]

Tan,
Since you're on compression driver why not try out the waveguide instead? IMO they should sound much better than the short horns.

http://www.partsexpress.com/webpage.cfm?&WebPage_ID=3

OTOH I've never grown to like compression drivers, somehow the treble produced are just too fatiguing. Great for large outdoors or hall filling sound, but definately not for near field audiophool listening distance.

I'm also building something similar to your OB, I'm using 4x Visaton BGS40 15" woofers in W-frame config (plus an extended rear cavity - so it is a hybrid w + u frame), mtm ob comprising 4xB200 Visaton mid and Fauntek neocd3.0 ribbons.

cheers.

[ttan98]

Tan,
Since you're on compression driver why not try out the waveguide instead? IMO they should sound much better than the short horns.

http://www.partsexpress.com/webpage.cfm?&WebPage_ID=3

OTOH I've never grown to like compression drivers, somehow the treble produced are just too fatiguing. Great for large outdoors or hall filling sound, but definately not for near field audiophool listening distance.

I'm also building something similar to your OB, I'm using 4x Visaton BGS40 15" woofers in W-frame config (plus an extended rear cavity - so it is a hybrid w + u frame), mtm ob comprising 4xB200 Visaton mid and Fauntek neocd3.0 ribbons.

cheers.

The B&C horns fits exactly to the the B&C CD, this is my first time trying horn, so I want compatibility and too much match and mismatch of different brands. Also, B&C horn is not too large and cheap too compared to waveguide at 2.5Khz X-over, which is rather large. When I have some more money I will try Gedlee's waveguide which seems to receive good reviews.
You will find B&C CD uses mylar membrane(not titanium), hence the sound is rather smooth not irritating, I was listening at close range for some time 1-2 hrs. I had no problem.

once you use a CD(very dynamic) I think it is difficult to go back to dome.
 

[scorpion]

This will be very interesting to read !

/Erling

[D OB G]

Hi ttan98,

As far as I know, there is no description of how to post images in the help menu.  (Unless I've missed it, there should be).

I keep forgetting, but I think it goes something like this:

1   Save image somewhere.
2   Go to Gallery, and go to own gallery.
3   There is an option to upload an image, using a "browse" line, to find your saved image.
4   Once it confirms successful upload, you need to chose where to put it (say for example, new gallery)
5   This will need to be confirmed.
6   Once it is placed in your gallery, and you have opened your gallery, you can double click on the thumbnail of the      image, to produce the image full size.
7   Right click on the opened image, and then click on properties.
8   The file name will appear on the opened box, prefaced by http:/
9   Select the whole name of the file, including the http:/, and press Ctrl C to copy it.
10 Go to your reply page, and press the image icon.  It should bring up [...img...][/...img...].
11 Press Ctrl V to insert your image at the cursor between [...img...] and [/...img...]. (The dots don't actually appear, but if the img code is written properly, an empty image will appear anyway).
12 Go to preview, and your image should appear.

I may have left some steps at the gallery stage out, but this should work.

Facilitator, if these instructions appear in the help menu, could you please tell me where, if not, could something please be included.

David

[mcgsxr]

I think you covered it very well, but in case there is some confusion, there is a sticky in this thread, posted by TheChairGuy.

http://www.audiocircle.com/index.php?topic=40968.0

I look forward to learning more about this project!

[ttan98]

Thanks fellows so helpful in explaining how to insert images. I will try now hope it works.

Notes:

The setup is only experimenting only hence the looks is very 'Rough'. Now I have decided  on the MTM configuration I will build a final version that will look much better. BTW I have joined the local woodwork club so that can access to their tools, cool!

The wings are not at the right height(left over from previous baffle). A wider baffle maybe included in the final version. The wider baffle will reduce the bump around 200-400Hz region. My experience is that the bump is about 2dB.

Note the U-frame below the MTM.

[Norris Wilson]

Hi ttan98,

Your OB speaker looks good, and similar to what I would like to build.

I have a few questions regarding your design and results of your OB and U baffle subwoofers.

I want to build an OB where the midrange would use 2 JBL 2118J woofers in an MTM configuration.  With a B&C DE-250 CD and DSS ENG 90-1 wave guide for the tweeter.  I may decide to use some type of super tweeter, since CD tweeters seem to be lacking that fine high frequency details to me, like shimmer, sparkle and tinkles.  I am a little lost on what way to go as far as subwoofers are concerned.  I have considered the U baffle due to room placement versatility.
Also, the W/U baffle hybrid sounds interesting as well.
But, I have yet to find a suitable woofer for my desires.  There are a few on the market in the low efficiency realm.  Woofers like the Acoustic Elegance IB 15, Dayton IB 15, GR-Research OB 12", and soon to be released Exodus Audio IB 15.  The problem I find with these low efficiency subwoofers is, that they need allot of power to drive them to a level that will match the high efficiency midrange drivers.  Therefore, I feel a greater probability of distortion in the lower octaves will happen due to voice coil heating.
This some what defeats what I would like to achieve, a low distortion highly efficient speaker capable of high SPL's.  A speaker that can be easily driven by flea powered SET amplifiers on the midrange from 100Hz and up.

1. Would you tell me why you chose to go with the Visaton BGS40 15" woofers for your U baffle subs? 
2. What type of amplification are you using to drive your sub with, plate type, bass boost and EQ ability, class AB, D, ect? 
3. What type of in room bottom frequency response are you getting with the BSG40 U baffle subs? 
4. Do you find the need to add a great deal bass boost and equalization to a woofer with a low to mid Qts of .42 as the BGS40 have?
5. If you do equalize and add bass boost to your U baffle woofers, at what frequency do you add bass boost, and how do you equalize?
6. What is the crossover slope and frequency that you are using on the U baffle subwoofers?
7. And what type of slope are you using on the OB midrange section of your speakers, any equalization needed?

Thanks for sharing your OB design with us.  I hope you will find the time to answer my questions?

NW

[Danny Richie]

GR-Research OB 12", and soon to be released Exodus Audio IB 15.  The problem I find with these low efficiency subwoofers is, that they need allot of power to drive them to a level that will match the high efficiency midrange drivers.  Therefore, I feel a greater probability of distortion in the lower octaves will happen due to voice coil heating.

FYI, these are designed to be used in pairs or even with three at a time on one amp. One pair will have an output sensitivity of nearly 91db with one watt.

The matching Direct Servo amp is a 380 watt amp. So output wise it will keep up with most MTM sections just fine.

Also the Servo system will not only keep them flat to 20Hz, but this design minimizes voice coil heating and keeps distortion very low. In fact Distortion will be much lower than standard designs.

You can read about it in our forum.

[gitarretyp]

I want to build an OB where the midrange would use 2 JBL 2118J woofers in an MTM configuration.  With a B&C DE-250 CD and DSS ENG 90-1 wave guide for the tweeter.  I may decide to use some type of super tweeter, since CD tweeters seem to be lacking that fine high frequency details to me, like shimmer, sparkle and tinkles.  I am a little lost on what way to go as far as subwoofers are concerned.  I have considered the U baffle due to room placement versatility.
Also, the W/U baffle hybrid sounds interesting as well.
But, I have yet to find a suitable woofer for my desires.  There are a few on the market in the low efficiency realm.  Woofers like the Acoustic Elegance IB 15, Dayton IB 15, GR-Research OB 12", and soon to be released Exodus Audio IB 15.  The problem I find with these low efficiency subwoofers is, that they need allot of power to drive them to a level that will match the high efficiency midrange drivers.  Therefore, I feel a greater probability of distortion in the lower octaves will happen due to voice coil heating.
This some what defeats what I would like to achieve, a low distortion highly efficient speaker capable of high SPL's.  A speaker that can be easily driven by flea powered SET amplifiers on the midrange from 100Hz and up.

Norris,

I'm actually in the process of putting together a similar design, so i have some thoughts i can add:

1) From my own experimentation, part of the reason for the lack of shimmer, sparkle, ... of CD drivers is the peaky response. If you apply judicious EQ to flatten the response, you should find that those qualities return.

2) If you want high efficiency in the bass, you need to look at prosound drivers (the eminence kappa lite-3015lf looks quite nice) or use multiple hifi drivers. The Peerless sls or xls, Dayton reference series, or Danny's subs in pairs in a shallow u baffle will get you mid to low 90s sensitivity at ~100Hz. All of the afformentioned drivers have been used quite successfully in this application. Personally, i'm going to try 4 of Danny's m165x per side (roughly the area of 1 12"), but i plan to high pass in the 60-80Hz range.

3) You probably already know this, but one of the most important properties for an OB woofer or midrange to have is low self noise. The drivers i mentioned above all reportedly have very low self noise, which i why i suggested them. One driver (B&C 10NW64) i tried out for use as a midrange (ie, down to ~200Hz) had terrible self noise at moderate volume levels unless i crossed over 4-8th order a little above 200Hz and was completely unusable in an OB.

4) If you haven't already, you should download Xlbaffle.xls. You can vary the power input by changing the Thermal Power Limit Parameter and looking at the Power Resp Woofers in Room tab to get an idea of the power and output necessary with your combinations. Remember that when running multiple drivers in the program, you need to adjust VAS, Re, and xmax accordingly. Also, you should model your JBLs with this program as well. Using them to 100Hz on a flat baffle may require more power and eq than you think.

If you're planning to run these full range and have high output (110db) below 40Hz, you're going to need lots of power, displacement, and baffle regardless of what you choose.

[ttan98]

Norris,

You have used components that far superior in terms of performance and price than mine. i will try to ans some of your query.

1. Would you tell me why you chose to go with the Visaton BGS40 15" woofers for your U baffle subs? 
I did not use Visatron, I bought some of the local 12"woofer(QTS=0.56) here and they seemed fairly slow and I am thinking of upgrading them. I have a few options including those you mention. OB Woofers from GR seem attractive however after adding the price of servo it would blow my budget. Low efficient woofer from Exodus audio is not a good option as well. It may boil down to using either Eminence Beta 15"(qts=0.58) or Warrior 15"(qts=0.88). I cannot get warrior as by the time it reaches me it would very expensive, go to this site for details:
http://www.shredmuzic.com/SearchResults.asp?Search=warrior+&Search.x=13&Search.y=11

warrior woofer 10" to 15" have Qts>0.8 are very suitable for open baffle, you may not even have to use U-frame. one or two users seemed to like the sound, search DIYaudio. Magnetar from DIYAudio uses the warrior 10", but apply a high pass filter at lower end. He explained better at this site:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=116871&pagenumber=2

 
2. What type of amplification are you using to drive your sub with, plate type, bass boost and EQ ability, class AB, D, ect? 

I don't have a sub. I use straight forward class ab amp. to drive the  Uframe woofer. I am building chipamp to drive, about 50watts per woofer. maybe more is better, say 100W/channel.


3. What type of in room bottom frequency response are you getting with the BSG40 U baffle subs?

With my woofer U-frame I can get it flat till 50 Hz. be careful you need to pad up the enclosure to reduce resonance.

 
4. Do you find the need to add a great deal bass boost and equalization to a woofer with a low to mid Qts of .42 as the BGS40 have?

if you use low Qts(less than 0.6) woofer you need either U-frame or H-frame otherwise the freq response rolls off too quickly. You can still apply equalisation even if you use U-frame, obviously you must not exceed the woofer x-max when played loud.


5. If you do equalize and add bass boost to your U baffle woofers, at what frequency do you add bass boost, and how do you equalize?

this you have to experiment. start with centring around 30hz, again easy with DCX.

6. What is the crossover slope and frequency that you are using on the U baffle subwoofers?

Experiment if you use dcx it is very easy, just dialling the x-over, mine is 150-200hz.

7. And what type of slope are you using on the OB midrange section of your speakers, any equalization needed?

2nd order LR, again if you use DCX you have many options.


HOPE THIS HELPS.

[ttan98]

1) From my own experimentation, part of the reason for the lack of shimmer, sparkle, ... of CD drivers is the peaky response. If you apply judicious EQ to flatten the response, you should find that those qualities return.

Some good quality CDs from B&C and BMS that use non-titanium membrane do not give this rising freq., they are very smooth.

2) If you want high efficiency in the bass, you need to look at prosound drivers (the eminence kappa lite-3015lf looks quite nice) or use multiple hifi drivers. The Peerless sls or xls, Dayton reference series, or Danny's subs in pairs in a shallow u baffle will get you mid to low 90s sensitivity at ~100Hz. All of the afformentioned drivers have been used quite successfully in this application. Personally, i'm going to try 4 of Danny's m165x per side (roughly the area of 1 12"), but i plan to high pass in the 60-80Hz range.

If I am not mistaken Danny tried them ie M165x and they are not suitable for OB, qts is low about 0.3-0.4. I suggest you contact Danny.

[gitarretyp]

1) From my own experimentation, part of the reason for the lack of shimmer, sparkle, ... of CD drivers is the peaky response. If you apply judicious EQ to flatten the response, you should find that those qualities return.


2) If you want high efficiency in the bass, you need to look at prosound drivers (the eminence kappa lite-3015lf looks quite nice) or use multiple hifi drivers. The Peerless sls or xls, Dayton reference series, or Danny's subs in pairs in a shallow u baffle will get you mid to low 90s sensitivity at ~100Hz. All of the afformentioned drivers have been used quite successfully in this application. Personally, i'm going to try 4 of Danny's m165x per side (roughly the area of 1 12"), but i plan to high pass in the 60-80Hz range.

Some good quality CDs from B&C and BMS that use non-titanium membrane do not give this rising freq., they are very smooth.

If I am not mistaken Danny tried them ie M165x and they are not suitable for OB, qts is low about 0.3-0.4. I suggest you contact Danny.

The rising response isn't that big a deal, though it needs to be tamed --its increases directionality at the upper end helps with this, as well. I found the roughness (peaks and valleys) of CD's response versus a good non-CD to be more of an issue.

The m165x have qts = 0.44, which is perfectly adequate for my use. If i were running them lower, i'd be more concerned with the fs than the qts. Four of them per side model nearly identically in response and output capability to a pair of 10" peerless sls or dayton rs270 drivers on the same baffle, but i chose the 165s for a few reasons. I plan to throw a test baffle together tomorrow. After i get everything finished in a few weeks, i'll post the project.

[ttan98]

gitarretyp,

how do you mount your 4 woofers?

[gitarretyp]

gitarretyp,

how do you mount your 4 woofers?

They'll be in a shallow, tapered u frame.

[ttan98]

gitarretyp,

how do you mount your 4 woofers?

They'll be in a shallow, tapered u frame.

mid&tweeter
WW
WW

or

W
W
mid&tweeter
W
W

if not list please.

[gitarretyp]

Sorry, i'm using a radian 5208 coax. So, it's
C
W
W
W
W.

Part of the design goal was to keep the baffle fairly narrow for the improved acceptance factor.

[ttan98]

Sorry, i'm using a radian 5208 coax. So, it's
C
W
W
W
W.

Part of the design goal was to keep the baffle fairly narrow for the improved acceptance factor.

you should use 10" warrior qts=0.88 , cheaper, some users like them incl magnetar, narrower u-frame. Better chances of successful implementation.