[roscoeiii]

Hi folks,

I am currently using the high pass filter in my NHT X2 sub crossover between my pre and amp, but am wondering if I might find some sonic improvement by using a different type of line level high pass filter and just use the NHT for the sub stuff.

Any thoughts? Anyone here played around with different types of high pass filters for their main amp?

[TJHUB]

Hi folks,

I am currently using the high pass filter in my NHT X2 sub crossover between my pre and amp, but am wondering if I might find some sonic improvement by using a different type of line level high pass filter and just use the NHT for the sub stuff.

Any thoughts? Anyone here played around with different types of high pass filters for their main amp?

I have had a hard time finding something for myself that doesn't negatively affect the sound.  Not easy!  The best I've heard to date is the FMOD's from PartsExpress.  I have been looking into the passive XM46SB from Marchand.  I'm close to picking one up.  My only reservation is that I'd need to use another pair of interconnects to use the Marchand.  More IC's is not high on my list, so I'm sticking with the FMOD's for now.

The only real negative to the FMOD's is the low slope.

[roscoeiii]

Many thanks. I will check those out. Low slope shouldn't be a big concern for me since my full range drivers are already beginning to decrease the crossover point...

Do post back if you pull the trigger on the Marchand.

[TJHUB]

For the money, try the FMOD's then.  Do some checking on your amp impedance though.  The actual x-over point is affected by your amp's input impedance.  I think they should work great, and PE has a great return policy.

I will post back if I go with Marchand.  Doubtful for now as I need to spend money on a new sub amp. 

Post back if you try the FMOD's.

[roscoeiii]

Where can I find how the crossover point changes according to my amp's input impedance?

FWIW my amp's input impedance is 100k.

[TJHUB]

Where can I find how the crossover point changes according to my amp's input impedance?

FWIW my amp's input impedance is 100k.

With a high impedance, the FMOD's listed x-over point is actual.  My amp was about 22k, so a 50Hz high-pass is really more like 70Hz. 

Here is the link to the fancy chart:
http://www.hlabs.com/technical/plot/

I hope that all makes sense.

[roscoeiii]

Yep, makes sense. Many thanks.

[JohnR]

I'd suggest trying a first-order filter first - all you need is a series capacitor.

Once you've settled on the value/frequency, you can go to town trying different types of capacitor.

[rollo]

  Have tried F-Mods a long time ago. have they been improved or changed recently. loved the affect but not the top end results. Thought the F-mods were bright and hard sounding in the upper mids and lower treble.
  The improvement in the midbass and midrange was quite good though, so for the cheap price try one.


charles

[TJHUB]

  Have tried F-Mods a long time ago. have they been improved or changed recently. loved the affect but not the top end results. Thought the F-mods were bright and hard sounding in the upper mids and lower treble.
  The improvement in the midbass and midrange was quite good though, so for the cheap price try one.


charles

I have no idea if the FMOD's have changed over the years or not.  I purchased mine within the last year.  All I can say is that I'd NEVER tolerate any level of "bright and hard sounding in the upper mids and lower treble."  I don't know what makes them work for me, but they just do.  So I agree, for the cheap price and return policy, they are worth a try.

[rollo]

  This has prompted me to try them again tonight. Maybe something elsewas up at the time. Now the system is there so maybe I missed something. Let ya know.


charles

[doak]

See this thread on another forum for a tutorial and useful tools:
http://www.hawthorneaudio.com/forums/viewtopic.php?f=1&t=3951

[TJHUB]

  This has prompted me to try them again tonight. Maybe something elsewas up at the time. Now the system is there so maybe I missed something. Let ya know.


charles

Did you try them again?  If so, how did it go?