Yellow Oaks

Designer: Nathan

Project Time: 8-20 hours
Project Complexity: Hobbyist
Project Cost: $100-$500

Driver Selection
Woofer HiVi F6 I love the look of the HiVi F6 it also gets good reviews and has good specs the price fit in the budget nicely. Tweeter Dayton Audio PT2C-8 I stepped out on a limb with this one. The Dayton wasn’t the best match, but the gold planar surface edged in black, looks nice paired with the HiVi one part of the goal is reached. I knew this would mean an Lpad. The price was less than 40 bucks each oh! Look at them now.

Enclosure Design
Enclosure type vented. I chose the bass reflex design for a little better efficiency and an improved low end.

Amplifier/Crossover Configuration
I chose a first order for the woofer and a third order for the tweeter, cross over point 2.5K. Using the third order for the tweeter allowed the PT2C-8 to reach down low. I used the closest value I could find and combined values to reach the ones not available. The components are soldered on PC board and glued down with Gorilla glue. The board is then glued and screwed down with nylon screws to ¾’’ oak board. No loose parts here. CAPS Dayton Precision 1% Metallized Polypropylene Capacitors 5.1uF in parallel with .22uF for the 5.3 value for C1 an error of.037% should be just fine here 15.0uF parallel with 1.0 uF for the 15.92 value for C2 an error of.05% should be just fine Inductors Jantzen 18 Gauge Air Core Inductors .4 mH and removed windings to reach the value .38 for L1 .5 mH and accepted the .01 difference for L2 an error of 2% a little bit of a gamble but should be ok on the woofer. Lpad For the purpose of testing; I first installed a 100 watt Lpad to determine if calculated resistor values would do the job. I eventually settled on fixed values of 4.63 ohms in series with the tweeter and 5.83ohms in parallel somewhere around 7.5db-8db of attenuation. The variable Lpad will be a useful tool for future builds. Again I combined available part in parallel to reach needed values. Dayton Non-Inductive Resistors R1 =2 X 9.1ohm resistors in parallel to yield 4.55 ohms for the R1 value. A 1.7% error but it is within the 2% tolerance of the resistors. R2 I had to combine unequal values to get close I settled on (1) 12.5 ohm wired in parallel with (1) 10 ohm to yields 5.55 ohms this is a 5% error but after temporarily clamping in a correction resistor I couldn’t hear a difference so I decided to live with it. Using resistors in parallel has an added benefit of increasing the resistor circuit’s power handling capacity.

Enclosure Assembly
¾’’ oak glued and clamped. Internal volume (.43³’) H 18’’ W7’’ D 6’’. Port 2’’dia X 6.7’’legnth. The cabinet is tuned to 50 Hz and filled with shoddy pad sound dampening material “sort of old school but it was free and works just as well or better than poly fill”. Cross over mounted in the bottom. I can’t decide on the finish and as you can see one speaker has the Lpad mounted on the front, I will remove it and plug the hole with a decorative wooden dowel and drill the other and repeat the process.

I am very pleased with the sound and look of the nearly completed speakers. SPL 88.2db measured with a Simpson SPL meter at 1 Meter distance with the Simpson 260 multimeter peeking out at 2.5 volts. I know this is not very accurate but at least its plausible and all I have to work with. I did have a problem with the tweeters buzzing when the amp was turned up to -28bd. It turned out to be the plastic case and had a simple fix. I simply cut a high quality 1/16’’ gasket made of cork and rubber to isolate the unit from the woofer. No more buzzing. The speakers are very nice to listen to and have good range. They sound good at low volume as well as high. The lows mids and highs are all there. They want go super low “plotted value -3db@ 51hz’’, most of my favorites don’t go very low anyway and I’m not a big fan of subs for music, movies on the other hand benefit greatly. I am quite certain I met my goals with this build. Total cost< $300, you want find sound of this quality at the box stores anywhere near the price range. After a little more sanding I will choose finish and put them in the bed room oh by the way my wife likes the look and sound as well. About The Designer
I am an over worked engineer in the recycling community. My background is avionics. I love to spend time in the BlueRidge Mountains with my wife and near adult children I have completed 11 speaker projects over the years, some dating back to my teen year of the seventies, all of which I am proud to say sound at least better than commercial big box .

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