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correction of high freq(206e in a Jeriko) [message #20703]

Thu, 24 February 2005 14:04

Kane
Messages: 26
Registered: May 2009

Chancellor

Just builded a pair of Jeriko with Fostex fe206e instead of 208. The high freq is too loud and i hope someone can give me advice of what to do. The rest of the sound is so nice, do i have to treat the highs with a filter or is there any stuffing/damping aviable that can cure this problem?
Thank you!

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Re: correction of high freq(206e in a Jeriko) [message #20705 is a reply to message #20703]

Fri, 25 February 2005 08:15

akhilesh
Messages: 1275
Registered: May 2009

Illuminati (3rd Degree)

HI Espen,
YOu can try a step filter at around 700 HZ. Look at MArtin King's website to see how to make one. That should definitely tame the highs, and actually make the bass a little fuller!
-akhilesh

Click on the variable baffle correction circuit

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Re: correction of high freq(206e in a Jeriko) [message #20706 is a reply to message #20703]

Fri, 25 February 2005 08:17

Martin
Messages: 220
Registered: May 2009

Master

Since the high frequencies are coming from the front of the driver, and not out of the horn's mouth, you have two choices. You can raise the SPL of the lower frequency output from the horn, which probably means a redesign of the horn itself. Or you can try and tame the high frequency output of the driver, which in my opinion the most controlled and predictable method would be with a filter. The filter will allow a significant amount of adjustment to the driver's response that is completely reversible.

Martin

Quarter Wavelength Loudspeaker Design

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I would strongly recommend the same [message #20707 is a reply to message #20706]

Fri, 25 February 2005 12:29

akhilesh
Messages: 1275
Registered: May 2009

Illuminati (3rd Degree)

I tried the filter MArtin is talking about, and it certainly did tame the highs. Also, as Martin says, it is completely reversible, esp if you use alligator clips like I did

-akhilesh

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Re: correction of high freq(206e in a Jeriko) [message #20709 is a reply to message #20705]

Sat, 26 February 2005 07:45

Kane
Messages: 26
Registered: May 2009

Chancellor

Thank you both for the advice. I have looked up the MK´s BSC filter and i´m comfortable building this. Can i copy the hole filter at MK´s website or do i have to change the values on the parts?. I dont have much knowledge about this kind of filter and my books doesn´t get into it, so i feel a bit lost here. Is the BSC filter doing the same as the notch only boosting the lows instead of toning down the highs?
I would be very happy for a suggestion on the circuit values if i can´t copy the Martin Kings consept!!!!
I will soon post some pictures of the Jerikos and some comments of the building and the changes i did to it.
Thanx!

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Re: correction of high freq(206e in a Jeriko) [message #20711 is a reply to message #20709]

Sat, 26 February 2005 08:02

Martin
Messages: 220
Registered: May 2009

Master

The values shown in my Project #5 are probably a good starting point. The circuit lowers the output of the driver above the baffle step frequency so you will sacrifice some SPL efficiency. The bass output is not changed, only the mids and highs are shelved down to balance with the speaker's natural bass roll-off. I have no idea what to expect for a bass response from the FE-206E in the Jericho horn design.

If you look under my "General Speaker Related Articles" link there are a couple of write-ups on the circuit. A nice option is the variable circuit, you can buy the Ohmite rheostats on E-Bay at a significantly reduced price compared to what I paid for my first pair. I now have a stock pile of rheostats from E-Bay auctions for future designs.

Martin

Quarter Wavelength Loudspeaker Design

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Re: correction of high freq(206e in a Jeriko) [message #20713 is a reply to message #20711]

Mon, 28 February 2005 08:22

Ron brady
Messages: 5
Registered: May 2009

Esquire

Hi Kane and Martin
I just wanted to add that I have built and tried martins variable bsc resistor scheme and must report that it works great. Instead of the ohmite resistor I am using the 0-16 ohm side of a standard 8ohm variable L-pad ($5 each at Parts Express. I keep a pair of them with long leads and alligator clips as part of my audio tool box. They have become one of my favorite tools for speaker DIY.
Thanks for the GREAT TIP MARTIN
Ron Brady

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Values you can start with. [message #20714 is a reply to message #20709]

Mon, 28 February 2005 08:25

akhilesh
Messages: 1275
Registered: May 2009

Illuminati (3rd Degree)

HI Kane,
Try 2.5 MH choke with a 3 ohm resistor in parallel. Make sure the DCR of the choke is 1 ohm or less. If it's more, then increase the resistor (that is in parallel with the choke).
You can hget this stuff at parts express.
thanx
-akhilesh

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Re: correction of high freq(206e in a Jeriko) [message #20716 is a reply to message #20713]

Mon, 28 February 2005 12:18

Kane
Messages: 26
Registered: May 2009

Chancellor

Hello Brady
Is the variable L-pad you use the same as an regular attenauer(volumecontrol)? if so, i will easily collect some in my "forgottenbygod" place on earth i live. I agree and think it must be a nice gadget to have. My option is to order by mail resistors with different values just to try out whats the best. It will cost about 2,5$ each.
Thanks Brady/Martin
Kane

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Re: Values you can start with. [message #20717 is a reply to message #20714]

Mon, 28 February 2005 12:36

Kane
Messages: 26
Registered: May 2009

Chancellor

Hello Akhilesh
I also got a tip from Martin on mail : http://www.quarter-wave.com/Project05/BSC_Circuit.pdf
This shows a circuit for 206/207. This is a circuit for a ml tl project and it will maby be nice for me too if not the horn enclosure requires something else(maby not)? There is so much nice info on that website but in theese days im too busy to understand it.
Thanks!
Kane

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