My open baffle dipole with Beyma TPL-150

[Overkill Audio]

Hi Pano,

It was just 3mm hardboard baffle covered in the grey neoprene type under floor sound deadening material. This stuff is £45 for a 10 meter length by 1.2meter width. It comes with a peel off film on one side so its very quick and easy to work with.

Cheers

Derek.

[Pano]

Oh, cool. Clever idea. And I do like those foam roll edges.

[c2cthomas]

I remember seeing a guy that designed a frame type of construction and using rope suspension to hang his speakers from. If I remember correctly I saw this around 3 years ago but I don’t recall on which forum and of course now I cannot seem to locate anything about it. His design was open baffle and the baffle was isolated from the speakers by foam seals. The speaker was hanging from several ropes from both the top and sides of the speaker. The use of ropes from the top as well as the sides allowed him to align the speaker for mating with the baffle.

I have done a simple sketch to try and explain the concept but it is a quick effort on my part and you would need to adapt it for your individual use – if you used it at all.

Just some food for thought.

[mige0]

Originally Posted by Overkill Audio

Hi all,
...
Derek.

Derek – a short OT question.

Have you published polar measurements of your Manger horn somewhere?

You know - I am interested in that as the Manger does not release a "quasi plane" wave front into the horn due to its operating principle.
From scratch I would have thought that a horn is of no benefit of all – but you obviously prove the opposite.

Is there a link you could provide?

Michael

[Overkill Audio]

Hi Michael,

I have not got the room set up to do a meaningful polar response at the moment.
Most of my lounge is the playground for my twin sons ( 2 yrs old) and 6 year old daughter...!
I can only easily do on axis 1 meter measurements and 3.5meter ( listening position) room measurements with the DEQX/Earthworks mic.
I have a friend who actually has a very good anechoic chamber and full driver/ speaker test and measurement facility.

I hope to get a day of his time in January and then I will have a full range of independent professional results.

I can tell you that my horn profile is based on a conical "plus a little bit" for the first three quarters of its length, then a large over round to provide a smooth curved exit.
190mm throat, 250mm length, 520mm maximum external width, 25Kg before driver and "zero contact" clamp.
Sensitivity is now up to an average of 95dB for 1 watt at 1 meter.
I am still experimenting as I am very encouraged ( delighted actually!)with the sound quality.
Much more detail and less effort to hear it, really big increase in dynamics, tremendous body and tactile feel with vocals, beautifully balanced with piano, it’s all just a bit too good...!
I think I can safely increase the horns length ( and corresponding mouth diameter) and get up to 98dB with no sonic nasties.

If all goes well this new design it will be the flagship which I use to launch "Rainforest Audio" ( see previous posts) and start saving some biodiversity as well as giving the public access to great speakers at not much more than DIY prices.....

Cheers

Derek.

[mige0]

Thanx Derek, I did a step visit to the "Manger driver" thread in the meantime - veeeery intriguing !

I'm really tempted to do a dipole horn for the manger - just to give it a try (neither money nor time though) - the best part is that seemingly you can cross ~ one or two octaves lower compared to an AMT - looking forward to the polars to come next year.



Michael

[Overkill Audio]

Hi Michael,

Yes the Manger is both technically fascinating and quite beguiling to listen to, but only above 300Hz with a absolutely top flight active crossover...!
Being able to crossover at 300Hz ( 200Hz if you don’t mind a max SPL limit of 100dB) is a great advantage.
I am also looking forward to the measurements of the finished speaker, almost as much as listening to it!

Stig Erik,

I forgot to reply to your suggestion of moving the 15' PD driver lower down the baffle.
The main reason its right up close to the base of the Manger horn is that the crossover is in the 300Hz to 400Hz ( depending on SPL / stereo music / multi Ch home cinema) and you can hear the gap in between the drivers if you lower it ie top end piano at head height and left hand piano at the floor and female vocals at realistic height, male vocals at knee height...!

Also that space below the 15' PD is reserved for the 15 Beyma or an 18' Precision Devices custom driver I am still working on the final spec for. It will be very special...
Re the floor bounce, I bought a couple of really thick wool loop rugs and lined the backs with carpet underlay and leather. They really are great absorbers even at frequencies as low as 200Hz to 300Hz, plus high WAF...!



Cheers

Derek.

[skorpion]

StigErik,

If you have access to Clas Ohlson then this might be worth testing:
Clas Ohlson Internetbutik - Allt för en enklare vardag .
Link looks a bit funny but works.

/Erling

[Pano]

Originally Posted by c2cthomas

I remember seeing a guy that designed a frame type of construction and using rope suspension to hang his speakers from

Yeah, yeah, yeah. Over on the open baffle section of Audio Circle. Who was that? Rudolf? Sash cord to hold the drivers in place. I can picture it....

EDIT: Oh, no it was Skorpion, of course!
Here's the link. http://www.audiocircle.com/index.php?topic=40594.0

[c2cthomas]

Originally Posted by panomaniac

Yeah, yeah, yeah. Over on the open baffle section of Audio Circle. Who was that? Rudolf? Sash cord to hold the drivers in place. I can picture it....

Holy CRAP!!!!! How did i ever wind up over in that neck of the woods??? I don't even have a bookmark fer 'em

But i think you're right Pano - thanks for the tip - guess I'll need to check it out