Burhoe Inspired Room Flooder

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Cressy Snr
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Burhoe Inspired Room Flooder

Post by Cressy Snr » Fri Feb 16, 2018 10:43 pm

Starting on a new speaker tomorrow; one that combines my own quarter wave TL ideas, the ideas of Winslow Burhoe (ex of AR, Boston Acoustics, EPI among others) RIchard Dunn and Roy Allison into one speaker concept.

It is a semi-omni, that uses a little bit less of the rear wall and a bit more of the ceiling, to create the stereo soundfield.
I lashed one up a couple of weeks ago using my Flatback Banned speakers as the test beds and it worked so well I was gobsmacked at the results. I was going to take the lash-up to Steve's place for a bit of peer review, but the reults from the lash-up were so encouraging, I decided to build a proper prototype version and take that to Hull instead.

Pics will appear eventually.
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Tue Feb 20, 2018 6:49 pm

The speaker prototype is finished.
Quarter wave line is mass-loaded by a 3" port, 2" deep and exits into a slot load in the base of the cabinet:
Image
Main driver and HF fire at 120 degrees to each other.
Main driver is using the ceiling to bounce the sound downwards at the listener, whilst the tweeter fires on a gentle slope up to said listener. Main driver also uses the rear wall.

I'm well pleased with the sound quality.
As this speaker is working with some of the ideas of Winslow Burhoe, it is using the room in a slightly different way to the NVA Cube or Allison Six. The image hovers at about the same height as a standing person, which is something I was aiming for and have achieved nicely, with the design.

The design is very promising and sould scale up to use bigger drivers.
I'm looking forward to exploring thee capabilities of the room flooder.
The question with this small 6" drivered version. is - how big a room is it capable of flooding?
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Tue Feb 20, 2018 9:14 pm

Transmission line damping reduced to next to nothing. Just a tiny amount at the narrow closed end and BAM!
We have lift off!
Now we're cooking.
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Tue Feb 20, 2018 10:13 pm

Bit more testing with a wide range of programme.
The flooder does what it says on the tin - it floods the room. This is going to sound counter-intuitive, but by using the room effectively, the flooder appears to take the room out of the equation.

Bass is even handed and free from boom whether one sits in the centre of the room or near corners or boundaries.
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Re: Burhoe Inspired Room Flooder

Post by gninnam » Wed Feb 21, 2018 11:30 am

Great result and they look nice too!

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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Wed Feb 21, 2018 12:35 pm

gninnam wrote:
Wed Feb 21, 2018 11:30 am
Great result and they look nice too!
Thanks! :)

At the moment, they are a lash-up; built from bits of my old Flatback speakers, plus some MDF side cheeks. However, though they use the same drivers, the sound is very different, due to the difference in the way that these speakers interact with the room.
The ratio between the direct and the reflected sound has been tilted (literally) slightly more towards the direct and I think I have hit the golden ratio; in my almost 10ft high ceilinged room at least.

I've been interested in the work of Winslow Burhoe for around 12 months and started to feel that, good though the Allison Six NVA Cube approach to room interaction is (and it's bloody good) there was room for improvement.

The good localisation cues provided by the Allison/Dunn approach of the forward firing tweeter were something I didn't want to lose, but at the same time, the vertical firing main drive unit is heavily dependant on the proximity of a rear room boundary in order to get 'presence' to the soundfield; fine in average sized rooms, but in larger rooms, the rear wall proximity output ends up being significantly weakened by the lack of any other nearby room walls to the left, right and (nine times out of ten) above. The result of this is that the speakers can, all too easily become "lost" in the room, and all you end up with then, is the thing puffing and wheezing away to itself and simply not communicating.

The frustration I have with this, b'stard of a large room problem has prompted me to look seriously at the Burhoe flooder incorporating the Allison/Dunn forward tweeter approach to the omni/semi omni conundrum.
The decision to go ahead was also triggered by Simon's successful (I think) ceiling proximity kitchen flooder speaker adventure.

The conventional flooder has both the tweeter and the main driver firing up on the diagonal as in various Direct Acoustics (Burhoe's current firm) Shahinian and Larsen models.

All I have done is to combine the two methods into one speaker design. They work very well in my own room, better than the straight up firer, and they are going to Steve's shortly, to see how they perform in a large room. The way they work there, will tell me if the design is worth scaling up for bigger rooms or not.
Last edited by Cressy Snr on Wed Feb 21, 2018 12:51 pm, edited 2 times in total.
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Re: Burhoe Inspired Room Flooder

Post by pre65 » Wed Feb 21, 2018 12:43 pm

Good to see your progress Steve.

Look forward to how they get on at Steve S house.
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Wed Feb 21, 2018 1:15 pm

pre65 wrote:
Wed Feb 21, 2018 12:43 pm
Good to see your progress Steve.

Look forward to how they get on at Steve S house.
Yes,
It's been a long old road; the journey down which for me, has been spoiled somewhat by a great deal of unnecessary unpleasantness.

That a ruddy speaker design could have caused such a frack arse, saddens me greatly. But though I was a few months ago, very tempted to just abandon the whole thing for the sake of maintaining good relations, and (if the truth be told) my own mental health, I'm glad I stuck with it.

What I'm hoping the visit to Steve's will show is that although both the flooder and the Allison/Dunn approach to semi-omnis is equally valid, there is another way: a way that combines the two of them into one "super semi-omni" - one that improves on both.

We'll soon find out one way or the other.
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Re: Burhoe Inspired Room Flooder

Post by IslandPink » Wed Feb 21, 2018 6:20 pm

So I had a brief look on the Burhoe site - is there a page with any tech/philosophy on their approach ?
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Wed Feb 21, 2018 8:07 pm

IslandPink wrote:
Wed Feb 21, 2018 6:20 pm
So I had a brief look on the Burhoe site - is there a page with any tech/philosophy on their approach ?
Nah! It's all disjointed and everywhere. The guy seems to be an eccentric untidy creative type after my own heart.
My interest was piqued by this review in Stereophile of the Silent II speaker, where we get a vague idea of his philosophy on design and the importance or not, that he attaches to things like stereo imaging and phase.

I was particularly interested in the weak areas of the design, as I knew that the Allison/Dunn forward firing tweeter arrangement, combined with the Burhoe tilted top face, had a good chance of solving the problems inherent with semi omni design.
I was right. The two approaches put together do the job

here is the review that started me thinking http://directacoustics.com/?page_id=301
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Re: Burhoe Inspired Room Flooder

Post by steve s » Wed Feb 21, 2018 8:35 pm

Can't wait to hear them steve
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Wed Feb 21, 2018 8:55 pm

Epicure Model 20 is very similar to what I came up with, and is an older Burhoe type design.

Image

There's nothing new in what I'm doing. The idea is there in this pic, but I only have the tweeter in the front position.
steve s wrote:
Wed Feb 21, 2018 8:35 pm
Can't wait to hear them steve
I don't think my speakers will trouble your big baffles Steve, as there is only so much you can achieve with a six inch driver, but I reckon you and Ed ought to be able to hear how the concept behind my original omnis had has been refined....a lot. :)
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Re: Burhoe Inspired Room Flooder

Post by ed » Wed Feb 21, 2018 9:06 pm

I'm looking forward to this a lot. You know I'm not a great fan of omnis, but I appreciate others that do like them a lot and I'm still intrigued by the old ways that seem to have been neglected...a bit like the walsh approach, which has all but been forgotten...

fingers crossed..

here's a bit more :

http://www.humanspeakers.com/e/index.htm

diet: there is some interesting info about Burhoe in the history section under the epi menu.
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Re: Burhoe Inspired Room Flooder

Post by Cressy Snr » Fri Feb 23, 2018 6:59 pm

Well the speakers certainly managed to flood a large room this afternoon.
Apart from a bit of straining with Led Zep at too high a volume, they filled the room satisfactorily.

What this tells me, is that the concept of mixing Burhoe and Allison, works very well, is good to go and its performance in Steve's room, means, that much like my original Fostex FE108EZ Metronomes were, the design is scalable for bigger drivers and cabinets.
Should keep me occupied then :D

Thanks for the use of your living room Steve. :thumbright:
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Re: Burhoe Inspired Room Flooder

Post by steve s » Sat Feb 24, 2018 1:02 am

No problem Steve
The little ? speakers sounded great today I was really impressed. I don't think you could wring any more than you have done from those drivers. They had an impressive bass considering the size but the star of the day for me was your amplifier, it was really good.
Lush, detailed and just so easy to listen too. I thought it was easily your best yet.. quite an achievement Steve

I was also impressed with Ed's old amp, it sounded great on Steve's new speakers too
A great day
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