Author Topic: Hybrid open baffle build  (Read 599 times)

Offline Curlycat

Hybrid open baffle build
« on: June 23, 2018, 03:32:27 PM »
Hybrid because it is a combination of vintage drivers and modern drivers. Hybrid because amplification is a vacuum tube preamplifier and a solid state power amplifier.

This is not a high-tech expensive jaw-dropping build. It is more a build to express what was done with inexpensive parts, an easy build that resulted in the best sounding system I have had (I have gone through a lot - some very well known and admired kit) Apologies for the quality of the pictures, I actually had no intention of posting this build thread.

The build was designed around a quad set of vintage alnico Philips AD1255 drivers. (Thank you Kent Kassler - as always!)
Since I had 4 drivers, I planned to do a MTM (midrange-tweeter-midrange) setup for the top section and a big woofer for the bass at the bottom.

Here the Philips arrived and a quick connect up to hear what they sound like. They are 12" full-range drivers.



The baffle is made from standard off the shelf laminated pine shelving. I purchased one length of 2.4m x 610cm wide. This was cut in two to give me two baffles of 120cm high.





Getting ready to test on the baffle for the first time. This is the big moment when I will actually hear what these drivers sound like on a baffle.



It was a go! They definitely had potential to proceed with the planned build.

Next was to drill the hole for the tweeter and to add the wings. I wanted to keep the mids and tweeters as close together as possible to assist with pinpoint imaging. I suppose one can actually call it a U-frame open baffle. In my experience with open baffle designs, I always achieved better sonic results in the midrange with a bit of a side wing. In the past, no wings sounded a bit thin. The wings once again, shelf bought pine, 2.4m x144mm two lengths cut in half. Solid pine this time, not laminated.  The woofer was mounted on a double baffle. I reinforced the bottom section with a second sheet of laminated pine.





Next up was to router the hole for the 15" PA woofer. I used a cheap Hybrid H200 15" driver. Specs of the driver were well suited for an open baffle build. Also does not have a foam surround, so I don't have to worry about foam rot over time.

The woofer was front mounted and the Philips was mounted from the rear, the reason is to try and keep the voice coils of all the drivers more or less in time alignment.





All the drivers mounted - just the tweeters still missing. I did some extra reinforcement on the top section of the baffle as well, since it was just a single sheet of wood. The vacuum tube preamp is visible on the left.






Offline Curlycat

Re: Hybrid open baffle build
« Reply #1 on: June 23, 2018, 04:07:20 PM »
The preamplifier is the DarkVoice 336 SE - really awesome piece of kit. Vacuum tubes are readily available, not expensive and easy to roll tubes to change the sound signature. One does not have to worry about matching tubes since there is only one of each kind.



The "power" amplification section is made up of three Yamaha chip amps. Still on a plankie - ok a repurposed piece of shelving. Really cheap with great sound.
"Power" amplification in inverted comma's because at 12V they only provide 7.5 WPC, but trust me, that's more than enough. If you want to provide party entertainment... look elsewhere ...

Here is a link with more information on the amps: https://www.youtube.com/watch?v=tDQw9DWQOaY&t=1s
I did the heat sink mod.





Power to the tri-amps are provided by a repurposed computer PSU. It provides clean 12V power and can do 32A. Not that I need 32 amps, the amplifiers draw each about 4 amps max, so 32 amps provide good headroom. I opened up the PSU, cut all the unnecessary wires and tidied it up a bit.














« Last Edit: June 24, 2018, 05:25:33 PM by Curlycat »

Offline Family_Dog

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Re: Hybrid open baffle build
« Reply #2 on: June 23, 2018, 05:02:55 PM »
Felix, your work fascinates me as always! Those Philips vintage speakers are certainly capable of good sound.

May I ask where you sourced the Y148 amp module from? Watched the video and I'm keen on trying one out.


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Offline CAD

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Re: Hybrid open baffle build
« Reply #4 on: June 23, 2018, 07:23:57 PM »
Another interesting build bud ,subscribed  :cool:
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Offline CAD

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Re: Hybrid open baffle build
« Reply #5 on: June 23, 2018, 07:41:41 PM »
Where did you source the YDA-148 amp board from ? I would love to try one
The way of the warrior is NO match for the way of the wife.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

Offline Curlycat

« Last Edit: June 24, 2018, 05:28:20 PM by Curlycat »

Offline CAD

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Re: Hybrid open baffle build
« Reply #7 on: June 23, 2018, 07:55:20 PM »
Thanks bud  :thumbs:
The way of the warrior is NO match for the way of the wife.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

Offline Curlycat

Re: Hybrid open baffle build
« Reply #8 on: June 23, 2018, 09:09:08 PM »
Anytime CAD  :2thumbs:

Each of the tri-amps have their own volume control, so I can easily adjust the gain between the bass, mids, and tweets.  Global volume is adjusted at the valve preamplifier. My computer mouse gives me remote volume control.

So staining was left to do and the crossover. Most of the XO parts came from Partsexpress. I ordered decent caps and did not break the bank by ordering silly money caps.



The tweeter is also cheap, but lovely sounding though -Dayton Audio:
https://www.parts-express.com/dayton-audio-nd20fa-6-3-4-soft-dome-neodymium-tweeter--275-030


The woofer came from NXT - Thank you BranJ for pointing me in their direction!
http://www.nxtleveltech.co.za/products/view/64


The crossover consists of a 2nd Order Butterworth for the woofer, the mids and tweeters are 1st order Butterworth crossovers. I phase shifted the mids. It just sounded better. Woofer crosses at about 150hZ, the mids at about 350HZ and the tweets at about 12000HZ. Because the 1st order crossover's slope is very gentle it mixes & blends well with the other drivers.

Inductors came from Ludo - thank you, sir! You've been a great help!
https://www.avforums.co.za/index.php/topic,54125.0.html



I cannibalized the inductors and added new caps.

Monting the crossover on a mdf plankie














« Last Edit: June 24, 2018, 05:46:50 PM by Curlycat »

Offline Curlycat

Re: Hybrid open baffle build
« Reply #9 on: June 24, 2018, 12:15:27 PM »
Here are the baffles finished. They have an angle of 4 degrees, it just sounds better angled a little bit back. It tends to make the sound a little warmer and fluid.








I still need to build some kind of chassis for the mini tri-amp.
« Last Edit: June 24, 2018, 05:48:44 PM by Curlycat »

Offline Chingy

Re: Hybrid open baffle build
« Reply #10 on: June 24, 2018, 08:20:01 PM »
Wow, Felix really excellent work,
I must also say, open baffle sound is something that everyone should hear.
Keen to try those inductors if there is still left for my build.
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Offline Curlycat

Re: Hybrid open baffle build
« Reply #11 on: June 24, 2018, 09:01:24 PM »
Thanks, Craig  :2thumbs: Plus one on your statement about OB.

Give Ludo a shout - sure he still has some left.