New OB Project: The Djinn

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matevana

Re: New OB Project: The Djinn
« Reply #20 on: 21 May 2017, 08:07 pm »
A few people have contacted me for the crossover component values most recently. The woofer's crossover was reworked post break-in, as the slight peak @ 500Hz all but disappeared once the stiff suspension loosened up a bit. This allowed for a more conventional second order electrical low pass, with an added resistor to shape the bass circuit. Instead of using a single electrolytic cap, I opted for a sandwich of three caps adding up to the required value. This allowed me to combine two inexpensive electrolytic caps and a third poly cap for better sound. The combined wire gauges also approximated that of the 14 AWG Solen inductor used in the same circuit.

The Eikona needs only one 33 ohm resistor in series to perfectly level-match the woofer. No other components in the full-range driver's circuit. Don't skimp here. I find that using the Mundorf M-resist Supreme resistors are about as transparent as one can get. The combined drivers present a very friendly load to most amps, about 7.9 ohms. 








« Last Edit: 23 May 2017, 11:00 pm by matevana »

Chicken Man

  • Jr. Member
  • Posts: 22
Re: New OB Project: The Djinn
« Reply #21 on: 23 May 2017, 06:54 am »
matevana,
                Not a point of criticism but I think you may need to reveiw your schematic for the woofer connection.

As presented, the circuit provides for a 1 ohm resistor across the woofer/capacitor combination which would no doubt be incorrect.

C.M 

matevana

Re: New OB Project: The Djinn
« Reply #22 on: 23 May 2017, 09:41 am »
Hey Chicken,

The 1 ohm resistor is In the leg of the circuit that shunts to ground. Swapping the value of this resistor affects the shape of the woofer's response. This type of shaping circuit is used by Troels Gravesen in some of his crossover designs. It can be helpful in OB applications to make up for a lack of the spring effect when the woofer is in open air.

JohnR

Re: New OB Project: The Djinn
« Reply #23 on: 23 May 2017, 10:29 am »
I think he has a point, there seems to be an error in the schematic. As drawn the amp is presented with a 1 ohm load at low frequencies. The schematic is also inconsistent with your schematic on the previous page.

:)

matevana

Re: New OB Project: The Djinn
« Reply #24 on: 23 May 2017, 10:49 am »
Oops, sorry guys!  I will edit the schematic when I get home from work.  Thank you both for bringing that to my attention.

Hearhead

  • Jr. Member
  • Posts: 12
Re: New OB Project: The Djinn
« Reply #25 on: 14 Jun 2018, 10:38 am »
Cool build!
Anymore insights on the merits of this type of slot loading?
By introducing an aperture on the woofer does it minimize the effects of backwave cancellation?
Thanks!

matevana

Re: New OB Project: The Djinn
« Reply #26 on: 19 Jun 2018, 09:56 am »
The folks at Jamo and Emerald Physics might say yes. In this particular design I was only able to measure a difference in where cancellation occurred, by manipulating the slots surface area as a percentage of the drivers radiating surface.