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ZOB active experiment (Read 15549 times)
Kimppe
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ZOB active experiment
12/09/13 at 11:53:04
 
Hello,

I have started a Zen Open Baffle experiment. I'm doing it somewhat different so I thought some of you might find it interesting.

I'm really hoping you will comment what I am doing!
It seems I need to post five text only messages before I can post links to pictures or manuals and datasheets. I'll put them up when I am able.

I am building active ZOBs. I have a Hypex AS2.100 plate-amp going into the left ZOB and then Hypex DS1.2 Sub plate-amp going into the right ZOB. (this might change still).

The AS2.100 has both digital and analogue input (usb/spdif/RCA). It has a computer interface via usb that lets the user filter the signals going to two channels plus one subwoofer.

The drivers I have are SEAS FA22RCZ full-range 8" elements.

When I was surfing the web i came across the Zen Open Baffle and I really find the idea and design interesting. So I have started the project of making the cabinets.
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« Last Edit: 12/09/13 at 11:54:34 by Kimppe »  
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Lonely Raven
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Re: ZOB active experiment
Reply #1 - 12/09/13 at 22:11:54
 
I'm looking forward to seeing what you build - I love watching DIY projects.

What wood are you using?
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Kimppe
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Re: ZOB active experiment
Reply #2 - 12/10/13 at 06:55:30
 
The wood is particle board (720 kg/m3).
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Kimppe
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Re: ZOB active experiment
Reply #3 - 12/10/13 at 06:57:04
 
The cutted edges will need some filling and then I'll paint everything but the front panel black.
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Kimppe
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Re: ZOB active experiment
Reply #4 - 12/10/13 at 06:58:27
 
The front panel will be veneered, but I have not yet decided what wood to use for that.
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Kimppe
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Re: ZOB active experiment
Reply #5 - 12/10/13 at 07:02:29
 
I was thinking that Walnut would be nice. I have the rest of my equipment and also the television in a Cabinet made of some similar wood.

But we have plenty of birch growing here in Finland and birch veneer would probably be considered more local design....
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Kimppe
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Re: ZOB active experiment
Reply #6 - 12/10/13 at 08:29:43
 
My OB experiment that I am turning into ZOBs looks like this now:


The first ZOB is coming along nicely:

made by Calle Smiley

and
http://www.berlins.fi/zob/2.jpg

The manuals for the amplifiers are here:
http://www.berlins.fi/zob/Manual_AS2.100_R5.pdf
and
http://www.berlins.fi/zob/DS12_manual.pdf
and the datasheet for the 8" element:
http://www.berlins.fi/zob/H1597-08_FA22RCZ_Datasheet.pdf
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Lonely Raven
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Re: ZOB active experiment
Reply #7 - 12/10/13 at 15:30:32
 

Is that particle board going to be solid enough?

The shape looks nice, I like the start!

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4krow
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Re: ZOB active experiment
Reply #8 - 12/10/13 at 23:08:24
 
I always applaud experimentation, at least in non-nuclear hobbies. Anyway, I too, will be conducting a couple of new experiments with the ZOB involving BSC and treble correction. The treble correction is really more about me and my hearing, but the Baffle Step Correction will be an experiment as to what might accomplished for the low end of this design. Having said that, I presently use a sub woofer along with this design, and find that the must be barely turned up(2-4 out of 50! of the Velodyne SMS-1). Never being less than curious, I want to try and let this speaker system do it 'all by itself'. The circuitry has been ordered, but will not arrive for some time. I will post at a later date to keep in touch.
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Kimppe
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Re: ZOB active experiment
Reply #9 - 12/11/13 at 06:55:19
 
The reason for choosing particle board here were economical.
One sheet of MDF would not have been enough and this particular particle board came in a more manageable size (600 x 2000 x 22 mm).

I don not know if the particle board is solid enough. Do you think that it might break at the weak point where the tuning slot is?  

I understand that MDF is often preferred by speaker builders.
It is considered a "dead" material. I'm not experienced enough to
know what that actually means but I have thought that it would mean that it resonates at lower frequencies due to higher mass (density) than other available materials.
 The particleboard I use here has a density of 720 kg/m3 and MDF is according to wikipedia 600-800 kg/m3, so no difference there...
 And as I understand it the most effective way of reducing resonance of the cabinet is by adding bracing to shorten the resonating "springs" in the construction.
 This has led me to the conclusion that MDF is preferred mainly since less work is needed to get a nice finish of the cutted edges.

Birch plywood is ofcource nice and also more costly.
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« Last Edit: 12/11/13 at 08:49:24 by Kimppe »  
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Lonely Raven
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Re: ZOB active experiment
Reply #10 - 12/11/13 at 18:20:00
 
Quote:
know what that actually means but I have thought that it would mean that it resonates at lower frequencies due to higher mass (density) than other available materials.


Sounds like you understand it perfectly. If they used a lot of binder in that particle board, it could be dense and durable enough. It just looks too much like the Ikea stuff that falls apart.  :)

Your workmanship looks excellent, and it's not like your hanging 18" woofers off of it, so you'll probably be fine!
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Kimppe
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Re: ZOB active experiment
Reply #11 - 12/24/13 at 10:09:47
 
The front panels are taking shape.
They consist of the same 22 mm particle board and another less dense (ordinary IKEA quality Smiley ) 12 mm particle board glued together. They are veneered with oak veneer and then there is a 10 mm strip of oak around the edges.

From the front:


From the back:


And the hole from the front:


The hole from the back:


The edges:


Now some sanding and then I think I'll apply oil or wax to the surface.
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« Last Edit: 12/24/13 at 10:13:57 by Kimppe »  
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Lonely Raven
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Re: ZOB active experiment
Reply #12 - 12/24/13 at 22:20:41
 

Nice clean work!
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Kimppe
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Re: ZOB active experiment
Reply #13 - 08/15/14 at 22:35:07
 
It's taken awhile but they are starting to look right
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image_012.jpg
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Kimppe
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Re: ZOB active experiment
Reply #14 - 08/15/14 at 22:38:34
 
Another picture
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image_013.jpg
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Re: ZOB active experiment
Reply #15 - 08/15/14 at 23:17:48
 
Those look great! Good work!
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Brian
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Re: ZOB active experiment
Reply #16 - 08/16/14 at 03:41:53
 
Those are beauties!
How do you like the sound?
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Kimppe
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Re: ZOB active experiment
Reply #17 - 08/16/14 at 17:52:24
 
The sound is great! The bass is much stronger than I expected.
They are passive now. In the end I didn't put the hypex in these. I just have an ordinary NAD amp driving the Seas elements. They are quite sensitive though so 25% all ready start to hurt my ears. I haven't done any measurements yet. Also I have the opening full open in the back. I need to find some good material to play when I start tuning.
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Kimppe
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Re: ZOB active experiment
Reply #18 - 08/16/14 at 18:03:28
 
Another thing is how "acoustic" the bass sounds. and one gets that airy feeling that I was looking for when I decided to build open baffles. So very enthusiastic now !
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image_014.jpg
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Kimppe
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Re: ZOB active experiment
Reply #19 - 08/16/14 at 18:35:02
 
I'll post a few pics
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image_015.jpg
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Kimppe
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Re: ZOB active experiment
Reply #20 - 08/16/14 at 18:36:24
 
So you can see how I did the wiring
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image_016.jpg
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Kimppe
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Re: ZOB active experiment
Reply #21 - 08/16/14 at 18:37:51
 
And then hid it behind the felt. Also You can see how I have fastened the front baffle to the cabinet
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image_017.jpg
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Kimppe
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Re: ZOB active experiment
Reply #22 - 08/16/14 at 18:40:16
 
Only two screws at the back.
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image_018.jpg
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Lin
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Re: ZOB active experiment
Reply #23 - 08/17/14 at 00:55:58
 
Kimppe wrote on 08/16/14 at 18:03:28:
Another thing is how "acoustic" the bass sounds. and one gets that airy feeling that I was looking for when I decided to build open baffles.


I agree. Cool

Nice looking speakers.


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« Last Edit: 08/17/14 at 00:57:24 by Lin »  
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Kimppe
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Re: ZOB active experiment
Reply #24 - 08/21/14 at 07:04:24
 
I measured the ZOB yesterday with a borrowed kit for measuring speakers. The software I used was HOLMImpulse. The microphone was a Dayton EMM-6. HOLMImpulse reads the calibration file for the microphone so it should be out of the measurement. The amp, speaker and microphone where connected to a "red box" that I was told should take the amp out of the measurement too.

That leaves the DAC and the speaker and the room. The DAC was a M-Audio Transit and the room a normal living room.

The blue line was measured 4 inch from the element.
The red line was measured i our sofa by my right ear.
THe green line was measured at the port opening at the back of the speaker.

http://www.berlins.fi/zob/ZOB_measure_4_2014-08-20.JPG

In the second picture
the blue line was measured ~1m in front of the speaker
the red line 15 degrees off axis
the green line 30 degrees off axis.

http://www.berlins.fi/zob/ZOB_measure_2_2014-08-20.JPG
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« Last Edit: 08/21/14 at 07:39:00 by Kimppe »  
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Steve Deckert
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Re: ZOB active experiment
Reply #25 - 08/22/14 at 03:49:18
 
Wow, great job! Very impressive, especially the measurements.  It's excellent to see other peoples measurements and how they compare.   My measurements of the ZOB were done with the FRX drivers and the response you've gotten is amazingly similar.  It shows how much a cabinet actually effects the response of a given driver.

Here is the FRX response in the ZOB in our listening room.



What is probably more fascinating is comparing your response to the published response of the SEAS driver:



Your response is quite a bit better.



Congratulations on a job well done!
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Kimppe
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Re: ZOB active experiment
Reply #26 - 08/22/14 at 12:40:42
 
Thank you for the response!
And thanks for the amazing design!!

I started to look at the measuremnet of the FRX you posted and started to see more and more similarities.

I couldn't keep my self from editing the measurements on top of each other. I scaled the axes so they were the same and shifted up your entire measurement a bit. I also did the 1/12 ocatave smoothing om my measurement. As a curiosity in red color I loaded an old measurement of the plywood baffle seen in the beginning of this thread Smiley.

By the way, I do not know how much power I was taking out of my amp when I was making my measurement. The volume was high. I did wear ear protection, but I'd say that it was still at party listening level (whatever that means).


http://www.berlins.fi/zob/ZOB_originalTestOB_FRX_copypaste.JPG
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« Last Edit: 08/22/14 at 13:48:51 by Kimppe »  
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Brian
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Re: ZOB active experiment
Reply #27 - 09/01/14 at 11:52:43
 
Kimppe said:
"Another thing is how "acoustic" the bass sounds."

I like that a lot!
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Kimppe
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Re: ZOB active experiment
Reply #28 - 09/03/14 at 19:22:25
 
Yes. I like it alot too!
I've been digging out every old Jazz record I have and I'm amazed how invisible the speakers are and how well I can listen to individual instuments or components of the music.

Do you think the model SE84CKC Super Zen Triode 2 watts stereo is fine for my elements?
The Seas FA22RCZ have a characteristic sensitivity (2,83V, 1m) of 94 dB.
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Re: ZOB active experiment
Reply #29 - 09/07/14 at 19:39:23
 
Thank you for the posts on your project! I have been researching OB with a focus on Steve's of course and this is great material. You made some great looking speakers and I am glad they sound good and work in your room. Keep us posted and yes I think Steve's 2 watter will do great on your speakers.
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Re: ZOB active experiment
Reply #30 - 10/07/14 at 03:47:58
 
Kimppe,

I sent you an email asking about how you fastened the baffle to the box.  I see the two screws in the top brace, but certainly that's not the only place the baffle is fastened.  Where else were you able to screw into the back of the baffle, since the box is all sealed up and inaccessible?

This is the only mystery on this build I haven't been able to figure out, and I'm getting ready to start my build.

Thanks!

Tom
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Kimppe
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Re: ZOB active experiment
Reply #31 - 10/07/14 at 07:33:32
 
Hello Tom,

you can see it on reply #19 and #21. I fastened (with glue and screw) a piece of the same particle board that the cabinet is made of back to the front baffle and then another bigger piece on top of it. This second piece will go inside the cabinet and "clamp" the front baffle to the cabinet.

Something like this:

http://www.berlins.fi/zob/zob_fb_fastening.JPG

The measurements above are in the right direction, not exact.

Best of luck with your buld!

regards, Kimppe
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« Last Edit: 10/07/14 at 07:34:20 by Kimppe »  
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Re: ZOB active experiment
Reply #32 - 10/07/14 at 12:52:40
 
Thanks!  That makes sense. Just to confirm I am clear on this, you have a "cleat" attached to the back of the baffle that slides (tightly) over the front bottom board (#1 in the plans) of the box.  This essentially traps the bottom of the baffle so it is tight against the box.  Then,  once the bottom of the baffle is slid down into place, the top of the baffle is attached with 2 screws through the back of the top brace, which is between the "ears" of the side panels.  Correct?  So there are no screws along the sides of the baffles, just the cleat and the 2 screws at the top.  Do you feel you have a tight enough seal between the baffle and the box with the felt all around the edges of the box this way?  
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« Last Edit: 10/07/14 at 12:53:12 by tlarwa »  
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Kimppe
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Re: ZOB active experiment
Reply #33 - 10/07/14 at 21:50:24
 
Correct!

In my case a thinner and less dense particle board (on the frontside of the front baffle) was glued to a thicker and denser one. As s result the front baffle bended just a little so I had to use force and bend it back with the two screws between the "ears". This means the cabinet is nice n' tight all the way from bottom to top.

If you manage to get the baffle to bend the other way you might need some other fastening method. ... Or just thicker felt

If you make the front baffle straight snd balanced I think it will be just fine with the cleat and the two screws.
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Re: ZOB active experiment
Reply #34 - 10/10/14 at 00:42:59
 
 It has been awhile since I built the ZOB cabinets, but this threadf has reminded me of some challenges. One in particular was the attachment of the baffle at the bottom end to the cabinet. Not sure that I would do it again this way, but I took very heavy duty deck screws(#14) about 10-12 inches long, and drilled from the bottom of the cabinet. I drilled at 50degree angle with a very long bit until it bored about 1/2" into the baffle. So then the screws held the baffle to the cabinet very tightly. At the top end, I was able to attach as recommended.
Just for the sake of experiment, The front baffle could be flipped upside down, making the chamber a sort of ported design. Overall, it had a bit too much bass, but was worth the try.
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