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back loaded horn - need advice from gurus.

Wharfedale Diamond 11 Series

amangujral06

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I have designed a lot of diy enclosures like voight pipes, Transmission lines , dual chamber dual ported , simple sealed, ported or bandpass, but i never had time to get into horn loaded enclosures. They are just too time consuming. This time i have decided to go ahead and make myself a rear/back loaded horn for a single 6.5" driver .

I am not going to use a full ranger like fostex or any other known brand , but a regular of 6.5" driver from 40hz-2khz , with a tweeter and a passive crossover. So here i am looking for forum members who have designed rear loaded enlosures using HORNRESP . I have a basic know of how to use hornresp, but i need to have an exchange of ideas and some clarifications with members already familiar with the designing of such an enclosure.

This is what i have in mind , but there are just some many options to play with. I can try all of those design choices , but i would rather ask members with knowledge of this dark art.
hornback.jpg
 

yogibear

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What little I know about BLH is, to have any meaningful output below 50hz will require a very large horn.

Many designs which claim to do so are not strictly BLH but a hybrid of TL.

Please correct me if am wrong. Would like to learn more about BLH and FLH. Thanks.
 

amangujral06

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Hey yogi, yes you are indeed right. Anything below 50hz can be quite big . Look at tannoy westminsters, they are huge. I have no space constraints, but i do have time constraints. I plan to go till 35hz . But there is soo little information out there to my specific need , that i just can't help but need a guru to guide me on this journey.
 

Hari Iyer

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Hey yogi, yes you are indeed right. Anything below 50hz can be quite big . Look at tannoy westminsters, they are huge. I have no space constraints, but i do have time constraints. I plan to go till 35hz . But there is soo little information out there to my specific need , that i just can't help but need a guru to guide me on this journey.
Contact FM Satyaki, he is the Horn Speaker guru.
 

yogibear

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Hey yogi, yes you are indeed right. Anything below 50hz can be quite big . Look at tannoy westminsters, they are huge. I have no space constraints, but i do have time constraints. I plan to go till 35hz . But there is soo little information out there to my specific need , that i just can't help but need a guru to guide me on this journey.

Thanks for reiterating. There are a few guys building or have built horns which do down to 20hz or IIRC 15hz. They are HUGE and many months of feat. These guys are my “Audio Noble Laureates” !!!

Isn’t pi speakers is great place to look for some nice plans ?

If I ever plan a horn, it will be from top to above 50hz. As far as horns are concerned, I have heard just some Calrad horns, perfect VFM and rated nearly to EV 350, nirvana 3500hz and above !
 

amangujral06

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I have done a fair share of research (months now) and looked through many papers written for horn design and building .I have calculated and designed some basic plans as well, but this is just a crazy field to deal with. If the problems were simpler edge diffraction, cabinet resonances, standing waves and 100 others such associated with enclosures, i would already have been on my way to built my horn. I already have a pair of speakers(currently working in open baffle) which i plan to use , so most plans out there don't even fit for the specs of my drivers.

I have heard joseph audios, top of line dali's, harbeths special editions and what not, but the day i sat in front of the westministers royals, i knew it wont be easy. that was the only day i only cared about music . Not the imaging, harmonic distortions, coloration, bass octaves, nothing !!

Today was a good evening. I was able to find one big information i need to further solve this design process. I will surely contact satyaki , horn building is expensive , specially the big enclosures , so its best i approach this problem with best i can.
 

yogibear

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I have original plans of JBL Hartsfield if you need. Interested in knowing your OB build. Would you share details on design, drivers ?

Thanks.
 

amangujral06

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Thanks for the offering but my driver is only 6.5" in size. Those hartzfield were designed for much larger drivers. I will share some pics of the OB in the morning and the details of the drivers to be used as well. As for now, i just finished designing a ported box for the intended drivers to evaluate its music fidelity/detail characteristics . Tomorrow plans will be sent to my workshop for its construction. Time to hit the bed, i am tired of yawning :)
 
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amangujral06

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So finally i had a breakthrough and found a thread on the world wide web for "how to use hornresp". There is a tool embedded in the sub menus that can determine if a driver is worth using in horn loading. After hours of playing and modelling through the software, i came to an understanding that my driver which is Flux audio MC2 6.5" mid woofer ain't worth the effort. The giveaway was its high "Q" . While it can still be used to get outstanding results of 130dbs at 60hz in room at 100watts, the enclosure it modelled was 3 times the volume compared to an equivalent fostex 6.5" full ranger.
To put this in perspective the box would be 7ft high , 3 ft deep, 3 feet wide.

I have the space to keep such behemoths, but its not worth the effort. So then ! I wont be making a BLH , for now atleast. I will see if i can get a hold on some fostex or other capable full rangers from friends visiting the land of red indians. Anyways, i will still share the ported box i modeled for these Flux drivers to my fellow DIY'ers. While the driver TS parameter are well suited for a TL ,I might do one after this build. Without furthur ado, here it goes...

The Flux drivers are from a Car Audio brand located in Germany , designed and manufactured in Germany and belongs to their Maestro Competition line up. Reason for choosing them was very simple, I had these lying around biting dust. The model is T160 MC2 , here is a link for them- Flux T160 MC2 . The Tweeters are from the same brand , but this time these are manufactured by a very known brand called "Wavecor" to flux's specifications . The model of these tweeter is HT25 MC and here is a link for them Flux HT 25 MC

IMG_20180312_221512_HHT.jpg

Here is the frequency response curve. I tried getting it as flat as possible even at an expense of some Db's. I didn't take edge diffractions and many such minor accountables in consideration as this is far from the final design.
Untitlaadded.jpg
The box is tuned at 49 hz, but in room placement will help me achieve a little more below 49hz. The response from 45hz-200hz is withing a margin of 0.5 db. Which is quite good for a first try. Even the group delay is pretty acceptable, peaking at max 24ms at 43hz.
Untitlaaed.jpg

Now that some calculations were done , i finalized the external dimentions in Torres tuning calculator software and drafted the cabinet designs in AutoCad for it to get CNC'd.
torr.jpg

ed.jpg

Today i was able to make some time out of my schedule and finish the CNC work . Here are all the pieces, waiting for me to join them in holy music matrimony.
IMG_20180312_221214_HHT.jpg
Hopefully by this weekend both the boxes will be ready for a music session with friends.
 

amangujral06

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One question, what material you guys think or with personal experience chosen to dampen high frequencies of 200 hz and above inside the cabinet.
 

amangujral06

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Interested in knowing your OB build. Would you share details on design, drivers ?

Thanks.

Hi yogi, as requested here are the pics of my unfinished build of OB. The drivers are from yamaha japan ,paper cone of of some japan specific tree pulp, yamaha tweeters from the studio monitor series ns6's .

IMG_20180328_38534.jpg IMG_20180328_55713.jpg IMG_20180328_4983.jpg


It is supposed to look like this >>>

image.jpg
 

yogibear

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Interesting build, quite presentable, room friendly and high on WAF. However, what is the specs on those Yamaha drivers ? The vintage Yamaha woofers that I have seen on eBay are 12" to do bass duty. Will that tweeter cross very low ? What is the reason for stacking rising triangular pieces at the bottom ?

Thanks for sharing.
 

amangujral06

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The yamaha drivers were sourced in bulk by a friend of mine, who too is an enthusiast. I have quite some lying around with me in spares , enough to make 4 more such towers. We never got any specs , apparently some models are made only for japan market and these are made in japan .
So, i tried them in various boxes , sealed, TL , Ported . All sounded like DUD ! Only when i accidentally placed them on a test board to test an amplifier that needed repairing did they shine !

Extremely fast transients , silk smooth vocals, and the ability to just disappear without any other design effort. The tweeters are crossed at 1.5khz and they are absolutely flat till 1.2khz. Th design was meant to appear to be floating from the ground. The stacked triangle is mere a support recessed inwards from all three sides so the tower can be fixed onto the base. The cloth once wrapped around shall make it look like the 3D view .
Also the stacked triangle looks cool :)
 

yogibear

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Sounds great ! Which model make is that tweeter ? You did not mention size of the woofers. How low do you estimate them to go given four of them ? Is the tweeter at ear height or higher ?

I think this could sound awesome. Kind of OB line array. Technically it is a 2 way, right ?

How do plan to run the ensemble ? Crossover, amps etc.

I believe the woofers are High Qts and may be high on Qms as well.
 

amangujral06

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Don't know the model number of the tweeter , it came out of my 80's studio monitor from Yamaha.
The midbass are 5.25inch drivers . This is kind of a line array which does present a cylindrical waveform . Inventer of curved line array design Don Keele made a design while working for JBL . He implemented resistors from 0db on top to -12 db to the lower most driver to eliminate ground reflections and make a perfect cylindrical wave to be presented at the listener.

This is a two way design. The tweeters are at ears height , with some unplanned wave guide using the front baffle , just to keep the imaging intact . I am using crossovers for the tweeters and natural roll off takes care of the midbass drivers. Currently my Denon pma1500ii , currently listed up for sale too drive these . A good 50watt rms makes the room windows rumble . The amp does 150watt , I never tried to go that loud anyway .

My old tube preamp amp with 15watt was plenty loud to take it down to 50hz .
While 45hz is easy at 50watts.
 

yogibear

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Yeah I know Don Keele CBT. He has kind of retired and some other guys are promoting his designs and working on them.

Don himself IIRC did an OB too but CBT was mostly boxed designs.

I think you can also experiment with this setup to try a 2.5 arrangement but then impedance on two groups would be 4 ohms. And 2.5 depends on Fs of your Yamaha drivers too.

Great effort and thinking. Thanks for sharing.
 
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