No baffle speaker (edit: some baffle speaker)

Polarbear · « **on:** 17 Mar 2010, 10:37 am »

I just wanted to share my latest project.

I had certain thoughts and goals for this project. I have made quite some baffels, and whats goes for all, are that they need to be heavy, sturdy, thick and bulky to not play along. I have long wanted something different. A less dominating and more versatile dipole. Both regarding to baffels, but also regarding to the drivers used. So magnet mount it is. Different techniques were tried but i fell down on a clamping the drivers to a "pole". To make the pole heavy, it needed to be sandfilled. Decoupling the drivers is also something I wanted to address.

So I started out with 6 pcs of Oak. Dimension 80cm * 30cm * 1,6cm.
I cut out the slots for the drivers, and also the middel board for the sandchamber.

Here they are slowly maiting

Time for glue. In the background, you also see the clampings laying around (cut out from the same oak):

Here is a closeup of the slot for the wideband driver. You also see the slots for the clamping :

Here, the base and clamps are mouted:

A place for the bass:

For the bass, there is just a rod going through, and srewed from each side.

The mounting of the widebander is a bit different. In the hole for the clamping, a rubberhose is first inserted. The rod then penetrates the rubberhose and the whole arrangement is decoupled from the rest of the speaker.

From above. As you can see the clamps for the midrange driver is countersinked for minimal obstruction. For the bass you need all the wood you can get for the sturdyness:

We need a hole on the top for the sandfilling:

Then sand. I used Olivin sand. That is a bit heavier than sandblasting sand.

I managed to get ca 4 kg of sand in each pole.

So what kinds of drivers am I going to use? There is also a tweeter coming on the top

More to come

JohnR · « **Reply #1 on:** 17 Mar 2010, 11:22 am »

Wow, that's awesome detail work!

Polarbear · « **Reply #2 on:** 17 Mar 2010, 11:38 am »

Thanks John

Yea, you have to somewhat dedicated to the project to bother. One of the poles broke at some time, and it was close to become firewood for the stove

After a while I just glued it back together

Proceeding. The tweeter need a bracket and a cradle to rest on. It weights a couple of kilos (heavy).

Polarbear · « **Reply #3 on:** 17 Mar 2010, 12:27 pm »

Tweeter in place

mcgsxr · « **Reply #4 on:** 17 Mar 2010, 01:11 pm »

Wow, this is a very unique approach, I have not seen anything like this before - I have seen folks using minimal baffles, I have seen magnet mounting, but the sand filled spine approach is very cool!

Polarbear · « **Reply #5 on:** 17 Mar 2010, 01:37 pm »

The drivers are used in different baffels for years now. It's the Bastani Prometheus and Hawthorne Augie. A killer combination

Tweeter:

Widebander:

Bass:

The drivers need a dress also:

More or less finished:

From the side:

Back:

Front:

From this side you can se the crossover:

The widebander is fullrange. The tweeter is crossed with a cap only. The Augie is actively powered.

Polarbear · « **Reply #6 on:** 17 Mar 2010, 01:43 pm »

Quote from: mcgsxr on 17 Mar 2010, 01:11 pm

Wow, this is a very unique approach, I have not seen anything like this before - I have seen folks using minimal baffles, I have seen magnet mounting, but the sand filled spine approach is very cool!

I may try with a baffle. It's stupid to not have a baffle around the Augie

The beauty of this approach is that i may use a thinner/easier baffle. Like glass or plexi. The baffle will not directly touch the drivers, only the spine. Will see

Bj

Polarbear · « **Reply #7 on:** 17 Mar 2010, 02:01 pm »

The connections are straight to the terminal lugs

jimdgoulding · « **Reply #8 on:** 17 Mar 2010, 02:14 pm »

Fan-freakin-tastic! Reminds me somewhat of the latest Gradient 3 ways. You may end up with a bonafide product there. Let us know how they are sounding. Thanks.

Polarbear · « **Reply #9 on:** 17 Mar 2010, 02:15 pm »

The Augies are crossed in at ca 100hz through a Behringer CX2310. I have not got around to do any measurements yet, but will do some day

I think the sound is better without the baffle. But that might just be the magnet mount etc. Maybe the sound will not suffer as much if I add a baffle at this moment. We'll see...

There are already issues I would do to better the construction. Add a board of oak and double the sandchamber. The bass really need to be controlled with a lot of mass behind it. Also the clamp for the bass should be doubled. The last issue I can easily fix, the former needs a total redo

Edit: Thanks for the kind words Jim

Bjørn

Bear · « **Reply #10 on:** 17 Mar 2010, 03:58 pm »

Very cool and refined looking job for a "first draft", have you considered using a hard dense compound of some sort around the magnets between the mounts. Maybe some resonant resistive strips to help grip the magnets if they are vibrating loose, as they will.

DanTheMan · « **Reply #11 on:** 17 Mar 2010, 04:04 pm »

Very Cool!

It will be interesting to see some measurements. Look for Stig Erikson's thread at DIY audio for crossover/EQ ideas.

Dan

painkiller · « **Reply #12 on:** 17 Mar 2010, 05:09 pm »

Awesome project!

Running the Augies without a baffle sounds a bit optimistic though.

They'll start rolling off pretty high, so you'll need some kind og compensation. Digital EQ would be the easiest solution I guess. Although a baffle would be the best solution in my opinion.

Do you know the T/S parameters for the Bastanis driver? Removing it's baffle could reduce bass response. So perhaps you need to reevaluate the crossover frequency for the Augies.

Measurements would be really interresting.

Polarbear · « **Reply #13 on:** 20 Mar 2010, 07:18 am »

Quote from: Bear on 17 Mar 2010, 03:58 pm

Very cool and refined looking job for a "first draft", have you considered using a hard dense compound of some sort around the magnets between the mounts. Maybe some resonant resistive strips to help grip the magnets if they are vibrating loose, as they will.

The clamps are quite tight but over time the Augies may rattel loose yes. I migth be trying some vulctape around the magnet, Not quite sure what resonant resistive strips are?

bj

Mr Content · « **Reply #14 on:** 20 Mar 2010, 08:33 am »

Cool work Bjorn, love it. I agree with you about mass. I think the bass mount should be heavier than the driver. But way cool,

Nig

Polarbear · « **Reply #15 on:** 20 Mar 2010, 09:48 am »

Quote from: painkiller on 17 Mar 2010, 05:09 pm

Awesome project!

Running the Augies without a baffle sounds a bit optimistic though. They'll start rolling off pretty high, so you'll need some kind og compensation. Digital EQ would be the easiest solution I guess. Although a baffle would be the best solution in my opinion.

Do you know the T/S parameters for the Bastanis driver? Removing it's baffle could reduce bass response. So perhaps you need to reevaluate the crossover frequency for the Augies.

Measurements would be really interresting.

Hi PK
I don't know the T/S parameter for the driver. But you are right regarding the bassperformance. I ran some sweeps, and have to cross the augie at 120hz to fill the gap. Earlier with a 40cm baffle, I crossed it at 80 ca. I guess a baffle in one way or another is coming along

I had to go offshore for some work, so I have time to think it out

cheers
bj

versus rider · « **Reply #16 on:** 31 Mar 2010, 07:00 am »

Hi, this idea really appeals to me, it doesn't look like the wood is supporting the driver baskets, if so, what was the idea of the wood following the shape of the baskets? Is the clamp on the magnet the only support for the drivers? You were talking about using a baffle for the augie, I think that defeats the object really, as surely point of this is its looks and its a case of working around the problem of having no baffle. A plexi glas baffle not connected to the driver would be better like you suggested. I am working on something like this myself, holding the drivers by the magnet but with a different support, haven't figured it out just yet but will post when I have. paul

Justincaz · « **Reply #17 on:** 7 Apr 2010, 01:09 pm »

stilig Bjørn!

your good with baffles!

im thinking about purchasing one of the bastanis kits along with augie`s for the summer, when i get back from Bergen.

i remember you used the digital behringer earlier, so i take it that the current cx2310 is good enough?
the cx3400 is availible online for a mere 1000kr. i could possibly go with that one?

still very happy with the bastanis wideband?

the guy i borrowed the tube dac with, (cant remember his name right now) what kind of sollution is he running now, did he get the sterling edition of hawthorne or something like that?

thx

-Richard- · « **Reply #18 on:** 7 Apr 2010, 11:02 pm »

Hi Polarbear ~

Let me also add my compliments... your work is beautifully realized... I can only imagine that the sound has a remarkable "presence".

While I was looking at some of your posted images Deborah walked into my studio... she was immediately captivated by some of the images and thought at first that your work was a sculpture (Deborah is a very sophisticated artist)... she is as impressed as I am.

Please let us know how things unfold for you as you learn more about the sound.

Warmest Regards ~ Richard

Polarbear · « **Reply #19 on:** 4 May 2010, 10:26 am »

An update on the project. I have added a baffle. It's just a fiber board (size 41*95 cm) with a profile at the top and bottom to get a curved form at the front. Then the whole front is covered in black "speakerfabrics", nailed to the back of the baffle. The curve and the cloth is just for making it less "science lab", since prototypes tend to stay for a while

The wideband is isolated with felt between the basket flange and the baffle. The bass is not so good isolated from the baffle. This transforms some energy to the baffle. I have to adress this later. The tweeter is just "floting" innside the baffle and is not connected to it.

I think the sound gets fuller with the baffle. Instead of crossing the augie higher, now the widebander has a better bottom (due to a wider baffle) and can be crossed 70-80hz.
Regarding isolating the vibration, I think the most important is to isolate the midrange. If not it might smear the sound. At this point the midrange energy is not transfered to the baffle. Remember that the bolts holding the midrange clamps are also isolated from the spine (inside a rubberhose).

Sound? I think it's for the better (as always

) And after getting the Virtue Sensation (run in), it's really getting good.

Remember I'm just a happy amateur

Bjørn