Ribbon OB TL Hybrid w/o XOs ;-) - diyAudio
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Old 4th April 2012, 02:26 PM   #1
deanxxx is offline deanxxx  United Kingdom
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Join Date: Mar 2012
Location: brum
Default Ribbon OB TL Hybrid w/o XOs ;-)

Hi all, This is my first real contribution on DIY Audio so here goes ;-)

I'm about to build an Open Baffle + Transmission Line hybrid using a PC as the source with a 10 channel Focusrite Safire playing audio files from Foobar2000 or J River with software crossovers.

I'll tri-amp the speakers with:

Roksan Kandy MkIII for bass
50w TL Audio amp (that claims to be Class A) for the mids
Sonic Impact Super-T amp for the tweeters.

Of course I'd like the amps to all be the same but for now I'm sure they will be just fine. Later I plan to add 2 Charlize2's For the Mids and Highs.

I'm actually going to build two (maybe three) versions of the mid/high OB panels using different drivers just for fun.


OB Panel 1 will have the following drivers:

TWEETERS >5kHz: affordable Beston Ribbon Dipoles (off ebay £90/pair).
http://www.ribbonspeaker.com.tw/RT00...r%20010213.pdf
http://www.ebay.co.uk/itm/3208792826...84.m1439.l2649

MIDS 250Hz - 5kHz: VMPS I got off ebay. Spec freq range: 160Hz - 6kHz.
eBay - The UK's Online Marketplace

BASS < 250Hz: Kef 6"x9" (the newer version) to keep the front profile slim. £60 for two off a fellow TL builder.


OB Panel 2 will have the following drivers:

TWEETERS >12kHz: Dali super-tweeters I had lying around.

MIDS 250Hz - 12kHz: HiWave BMR12. Spec freq range: 80Hz - 20kHz.
HiWave BMR12 Compact 2" Full-Range Square Speaker 12W 8 Ohm 297-210

BASS < 250Hz: As above using the same TL bass speakers.

I reckon OB1 will far better than OB2 on account of the VMPS mid drivers. I'm not sure what to expect from the BMR12's but I'm not banking on a stunning performance. We will see.


OB Panel 3 will have the following drivers:

As OB1 except the mids may use a 3" or 4" regular cone mid driver(s) - as per the diagram or in MTM format. Any suggestions on suitable drivers or alternatives to regular cones?


Diagrams:

Click the image to open in full size.
Click the image to open in full size.

Drawings arn't to scale, just sketches for now.


Any suggestions, observations, criticisms, ideas, etc...more than welcome.

Cheers folks,
Dean ;-)
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Old 4th April 2012, 05:04 PM   #2
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The Beston Ribbon Dipoles look like a good alternative to the now popular BG NEO3. The diyAudio community will be interested in your evaluation, and experience with the 10 channel Focusrite Safire.

JohnK's musicanddesign.com website provides a good education on the value of controlled directivity dipole speakers. JohnK provides data illustrating why the crossover between the dipole tweeter to a small area dipole upper midrange is critical for controlled directivity. It is important to keep the center-to-center distance shorter than one half the wavelength of the crossover frequency(fig2). JohnK's NaO Note uses the BG NEO3 and the well reviewed 3.5" Scan Speak 10F/4424G00. There have been discussions of similar designs using an 8"-10" midbass and a 15" or 18" H-frame dipole woofer in order to reduce both the speaker count and height.

MJK's quarter-wave.com website has great info on using a high Qts 18" woofer in an H-frame to generate enough dipole deep bass that a monopole subwoofer is seldom required. In the USA, the Goldwood GW-1858 Woofer from PartsExpress is one low cost favorite. In the USA, the Lambda TD8D 18" dipole woofer and 10" TD10D dipole midbass are popular for "ultimate dipole $$" dreaming. The 10" Eminence ALPHA-10A with Qts ~ 0.6 is a popular low cost dipole midbass.

The information on these websites might help you select the best of your options to build first.



MJK: "Starting with the H frame, the outer dimensions are 21” wide, 21” tall, and 16” deep. The baffle is made from a 20” square of ¾” thick plywood with the Goldwood woofer cut-out centered. The top, bottom, and sides are all cut from ½” thick plywood. I offset the baffle 1” forward in the H frame for two reasons, first I did not want the woofer’s magnet to extend past the back of the enclosure and second the acoustic center of the cone is probably about 1” behind the mounting flange. The distance from the front surface of the baffle to the front edge of the H frame is 7”."
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Old 4th April 2012, 05:23 PM   #3
deanxxx is offline deanxxx  United Kingdom
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Join Date: Mar 2012
Location: brum
thanx for the info LineSource, much to read.

I'll try to give the best evaluation as I can. Iv'e never built any home HiFi speakers before (knocked up some car speakers/sub in the mid 90s) and have never heard the Neo3s to compare. Anyway, I'll post my work in progress as it developes.

I like the safire very much, a bargain at £100 on ebay. It sound good to my ears and has a very quiet background, in fact, totaly black with all gains, sliders, knobs etc at 11!

Cheers...
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Old 11th April 2012, 05:37 PM   #4
deanxxx is offline deanxxx  United Kingdom
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Join Date: Mar 2012
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I did a quick test of the drivers I've bought so far:

2x HiWave 2" BMR drivers with a Dali super tweeter in MTM format:-


The BMR drivers sounded pretty bad tbh. I wasn't expecting a great deal from them at £10 each but they sound really nasal despite the frequency plot suggesting they are good (linear) from 250Hz to well over 10kHz where I cross over to the super-tweeter (actually at 12kHz). Also, the mids and s-tweeter seemed to integrate very poorly. I used Foobar2000 with software XO.

Admittedly, these drivers were a (very) long shot but I'm quite disappointed with them. Maybe they will sound better on a baffle or in an enclosure. I won't give up on them just yet, I could do with some audio measurement tools, but don't feel very motivated to try and polish these turds. I might just put them in a “sound bar” for a centre speaker for my HT setup.


VMPS ribbon planar mid with a Beston tweeter:-

Seems to show great potential. That's about as much as I can say for now. I need to mount them on a properly designed baffle to get a better idea of which way to proceed.


It's surprises me just how difficult it may be to design and build a pair of high quality speakers, even OB speakers which I'm led to believe are much simpler to implement. Having never built any home speakers before I guess I’m on a very steep learning curve.

Any pointers from the good folks of diyAudio is very much appreciated (and needed) ;-)

Regards.
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Old 22nd March 2013, 10:56 AM   #5
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Where did you get the FR plots for those 2" BMRs? I am looking at them for a car audio app. Do you still have yours and wish to sell them?
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Old 22nd March 2013, 11:56 AM   #6
deanxxx is offline deanxxx  United Kingdom
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Join Date: Mar 2012
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Quote:
Originally Posted by TheBaronGroog View Post
Where did you get the FR plots for those 2" BMRs? I am looking at them for a car audio app. Do you still have yours and wish to sell them?
I got the plots from the HiWave site:

http://www.hi-wave.com/downloads/dat...BM36S12-8A.pdf
http://www.hi-wave.com/downloads/dat...BM36S12-4A.pdf

Im going to hold on to mine but they are still available for a good price from parts express:

HiWave BMR12 Compact 2" Full-Range Square Speaker 12W 8 Ohm 299-208

cheers.
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Old 22nd March 2013, 12:31 PM   #7
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Thanks for the reply, IDK why I couldn't find them!

The ones you listed 1st, as owning are apparently different:
HiWave BMR12 Compact 2" Full-Range Square Speaker 12W 8 Ohm 297-210

To the ones they now do:
HiWave BMR12 Compact 2" Full-Range Square Speaker 12W 8 Ohm 299-208

But I can't see any difference?

Have you played around with them any more?

How's Brum today? Moved up here (northwest) last Dec
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Old 22nd March 2013, 01:04 PM   #8
deanxxx is offline deanxxx  United Kingdom
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Join Date: Mar 2012
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Quote:
Originally Posted by TheBaronGroog View Post
Thanks for the reply, IDK why I couldn't find them!

The ones you listed 1st, as owning are apparently different:
HiWave BMR12 Compact 2" Full-Range Square Speaker 12W 8 Ohm 297-210

To the ones they now do:
HiWave BMR12 Compact 2" Full-Range Square Speaker 12W 8 Ohm 299-208

But I can't see any difference?

Have you played around with them any more?

How's Brum today? Moved up here (northwest) last Dec
I see what you mean. Not sure if they are the same but they seem to be. Maybe they are a newer version. I didnt see anything on the HiWave sight to indicate a difference. I'd ask parts express just to be sure, they are very helpful.

I haven't played with them a great deal tbh but I reckon they would be pretty good in a car. Maybe they'd benefit from being boxed. They'd also sound better with a tweeter. I'm not gunna give up on them, I got high hopes for BMR technology.

Apart spring snow Brum is exactly as you left it ;-) I'm headed southwest soon I hope.

cheers.
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Old 22nd March 2013, 01:10 PM   #9
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I'll drop them an email, cheers.

I'm toying with a "wide-bander" set up for the car-I have a new Navara and it will take 2" drivers in the dash. I'm hoping to find something that'll play down to 300Hz so I can keep "all" the vocals up there and use some hefty midbass in the doors-I got the PE offer email and thought I might give them a pop.

Currently have a Dynaudio setup in my Mini which will move over-though had issue with rainbowing and the use of the 2" instead of a tweeter appealed-though you say these were a little nasal?

Very snowy up here, Ellesmere Port, good luck with the move south!
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Old 22nd March 2013, 01:37 PM   #10
deanxxx is offline deanxxx  United Kingdom
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Join Date: Mar 2012
Location: brum
Quote:
Originally Posted by TheBaronGroog View Post
I'll drop them an email, cheers.

I'm toying with a "wide-bander" set up for the car-I have a new Navara and it will take 2" drivers in the dash. I'm hoping to find something that'll play down to 300Hz so I can keep "all" the vocals up there and use some hefty midbass in the doors-I got the PE offer email and thought I might give them a pop.

Currently have a Dynaudio setup in my Mini which will move over-though had issue with rainbowing and the use of the 2" instead of a tweeter appealed-though you say these were a little nasal?

Very snowy up here, Ellesmere Port, good luck with the move south!
sound good. Have you considered some the more conventional full-range drivers? I reckon they could be better than the BMRs?

Vifa NE65W-04 2" Full Range Woofer 264-1046
Tang Band W2-748SG 2" Full Range Driver 264-861
Tang Band W2-800SL 2" Aluminum/Mg Full Range Speaker Driver 264-807
Vifa NE85W-04 2-1/2" Full Range Woofer 264-1052
Dayton Audio ND65-8 2-1/2" Aluminum Cone Full-Range Driver 8 290-206
Tang Band W2-803SM 2" Extended Range Speaker Driver 264-805
Peerless 830983 2" Full Range Woofer 264-1042
Vifa TC6FD00-04 2" Full Range Paper Cone Woofer 4 Ohm 264-1126
Tang Band W2-852SH 2" Shielded Speaker Driver 264-808


power handling is higher for most of those above but they are more expensive but still not silly money. Also, they may be available from European outlets, save some money on shipping.

;-)
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