High Pass Filter

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Kaiju2189

High Pass Filter
« on: 2 Apr 2022, 11:32 am »
I am looking to build a couple of high pass filters like the ones Danny talks about in his Sub integration and bi-amp videos.
Could someone share how to wire these. I think I understand but I would appreciate some expert feedback before I risk any gear.

The design was a capacitor inline with rca connectors to roll off the low frequency to the amp and speakers and a third rca for a full bandwidth signal bypass for the subs.

I have the calculator for the capacitor size needed but could use the help on wiring.

Hobbsmeerkat

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Re: High Pass Filter
« Reply #1 on: 2 Apr 2022, 11:38 am »
Heres a basic one i drew for someone else:



Kaiju2189

Re: High Pass Filter
« Reply #2 on: 2 Apr 2022, 11:49 am »
Wow. That goes down as the quickest reply ever. Thanks Hobbs!  I am probably missing something. But how do I also wire the bypass that would run to the subs without running through the cap? Thank for helping a newbie.


Hobbsmeerkat

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Re: High Pass Filter
« Reply #3 on: 2 Apr 2022, 12:40 pm »
Here's the insides of that same filter



Kaiju2189

Re: High Pass Filter
« Reply #4 on: 2 Apr 2022, 01:05 pm »
Thanks Hobbs. Glad I asked. Slightly different than the incorrect way I was going to do it.

Looking forward to seeing some of the potential new designs using the Neo 3 tweeter. Hoping to see another 90+ db sensitive speaker, maybe between the Otica and X MTM. I saw your thread today with a number of designs this morning. Looks like some good ideas are brewing! 

Onemusicalapple

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Re: High Pass Filter
« Reply #5 on: 7 Apr 2022, 11:21 am »
Hi everyone, new here and to DIY (although not to audio),

In my setup - running an integrated amp to a coming pair of GR LGK 2.0 kit speakers in small room - I don't have the option of a filter between pre and power amps.

My question: What value caps should be added to the kit crossover to roll off bass responce at 55-60 hz to cross with small fast sub? And what quality caps are needed? Guess pretty HQ caps since HF will be filtered through = $$$?

Thanks and kind regards

Hobbsmeerkat

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Re: High Pass Filter
« Reply #6 on: 7 Apr 2022, 02:28 pm »
When putting a high pass filter after the amp, sizes get rediculous.

You're looking at 300uF to roll everything off below ~65Hz
330uF for ~60Hz
360uF for ~55Hz
In which case youll need to purchase 3x 100/110/120uF per speaker. The bundled caps also be so large that you'll want go keep them external from the speaker.

The only way to use a single small cap would be with an electrolytic capacitor. And we really don't recommend that, it will really hamper the speaker's performance.

Hobbsmeerkat

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Re: High Pass Filter
« Reply #7 on: 7 Apr 2022, 02:33 pm »
The natural -3dB point is 80Hz, which will allow you to get away with 240uF instead.

And Solen does offer a single 240uF capacitor.
https://solen.ca/products/capacitors/fast-capacitors-250v-pa-series-metallized-polypropylene/solen-fast-capacitors-pa24000-240uf-250v-metallized-polypropylene-film/

Onemusicalapple

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Re: High Pass Filter
« Reply #8 on: 7 Apr 2022, 07:12 pm »
Thanks for your swift reply Danny 👍 Much appreciated! Did not expect a reply from the master himself (actually posted in the forum so as not to disturb you good folks at GR Research with what is probably a pretty generic inquiry).

Guess I'll skip the filter then and let them roll off naturally as you designed them and fill out with REL T Zero from 75-80 Hz.

Compliments on your work! - I have been looking for a HQ small speaker both fast on micro dynamics and with a natural tonal balance; pretty hard to find (as you would know) :-) Was considering LS3/5a types but been there done that, natural tonal balance spectacular, but tend to sound artificially slow and dead on the bottom end and dynamics.

Also: My sincere compliments for you sharing your substantial experience and knowledge on your YouTube channel, very inspirational, and confirms what I've experienced myself, without being able to dissect the factors behind it (advantages of bi-wiring being mostly marketing, low mass / small cone movement (tradeoff) sounding more natural,  Especially your point on spectral decay makes a whole lot of sense to me after having bought factory speakers for 20+ years in the §6-7k range and typically left unsatisfied with either the (too slow) speed of the woofers messing up micro dynamics and timing OR the tonal balance being too skeletal in fast sounding speakers, more often than not getting one or the other (Harbeth/Dynaudio vs PMC for instance).

Best regards from Copenhagen, Denmark

NoahH

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Re: High Pass Filter
« Reply #9 on: 7 Apr 2022, 11:13 pm »
Any sufficiently advanced Hobbs is indistinguishable from Danny.

lokie

Re: High Pass Filter
« Reply #10 on: 8 Apr 2022, 12:13 am »
Good stuff- thx

whydontumarryit

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Re: High Pass Filter
« Reply #11 on: 9 Apr 2022, 04:04 am »
Thanks for your swift reply Danny 👍 Much appreciated! Did not expect a reply from the master himself (actually posted in the forum so as not to disturb you good folks at GR Research with what is probably a pretty generic inquiry).

Guess I'll skip the filter then and let them roll off naturally as you designed them and fill out with REL T Zero from 75-80 Hz.

Compliments on your work! - I have been looking for a HQ small speaker both fast on micro dynamics and with a natural tonal balance; pretty hard to find (as you would know) :-) Was considering LS3/5a types but been there done that, natural tonal balance spectacular, but tend to sound artificially slow and dead on the bottom end and dynamics.

Also: My sincere compliments for you sharing your substantial experience and knowledge on your YouTube channel, very inspirational, and confirms what I've experienced myself, without being able to dissect the factors behind it (advantages of bi-wiring being mostly marketing, low mass / small cone movement (tradeoff) sounding more natural,  Especially your point on spectral decay makes a whole lot of sense to me after having bought factory speakers for 20+ years in the §6-7k range and typically left unsatisfied with either the (too slow) speed of the woofers messing up micro dynamics and timing OR the tonal balance being too skeletal in fast sounding speakers, more often than not getting one or the other (Harbeth/Dynaudio vs PMC for instance).

Best regards from Copenhagen, Denmark

'Guess I'll skip the filter then and let them roll off naturally as you designed them'

Is this what is recommended? No hipass filter on the 2.0 when used with subs. Are you sure you want to do that?
What good reason would there be for not doing it. I don't mean passively, of course.

Hobbsmeerkat

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Re: High Pass Filter
« Reply #12 on: 9 Apr 2022, 12:16 pm »
The main benefit of a high-pass filter is to give the LGKs better power handling, and has the secondary benefit of cleaning up the mids.

That said, if you can't achieve it by putting a cap between the amp/preamp, (ie using an integrated device) you're going to need a cap that is orders of magnitude larger to achieve the same effect.

For instance, high-passing to a 100KOhm amp will need a 0.015uF for a -3dB of 106Hz or 0.022uF for 76Hz.

On the speaker side, youre going to need a 240uF cap to get a roll off of around 80Hz or 200uF for 100Hz..  at which point it becomes expensive/impractical. It will also take up too much airspace inside of the LGK cabinet.

If your amp has the ability to adjust the bass extension to the speaker, then use that to attenuate the bottom end.
But if you dont have the ability, then there's not likely another realistic option, no?

mlundy57

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Re: High Pass Filter
« Reply #13 on: 9 Apr 2022, 12:50 pm »
I’ve had the LGK 1.0 in my office system for many years. This system has an integrated amp and a sub so no high pass filter. The LGKs roll off naturally and the sub is adjusted accordingly. Since the speakers are only 3ft away, they don’t need much power so not having a hgh pass filter is no big deal.

Would a high pass filter make them sound better in this situation? Possibly. Is one necessary? No. If you want to be able to high pass the LGKs, you will need to replace your integrated with separates. Will it be worth it? For me, in my office system, the answer is no.

My main system does have separates so I can use an inline high pass filter. However, this is not why I have separates in that system. I went to separates for all the other sonic benefits separates bring to the table. The ability to high pass the mains was an added benefit.

Every system choice has tradeoffs. Each person has to decide which tradeoffs work best for them.


joesap

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Re: High Pass Filter
« Reply #14 on: 11 Apr 2022, 07:32 pm »
Hobbs, can you share the formula to figure this out?

"For instance, high-passing to a 100KOhm amp will need a 0.015uF for a -3dB of 106Hz or 0.022uF for 76Hz."

-Joe

mlundy57

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Re: High Pass Filter
« Reply #15 on: 11 Apr 2022, 08:10 pm »
Hobbs, can you share the formula to figure this out?

"For instance, high-passing to a 100KOhm amp will need a 0.015uF for a -3dB of 106Hz or 0.022uF for 76Hz."

-Joe

As many times as this question comes up you migkt want to make the link to the calculator a sticky

joesap

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Re: High Pass Filter
« Reply #16 on: 11 Apr 2022, 08:52 pm »
Thanks for the suggestion Mike. I tried to be proactive and search for it but after 30 separate links to threads I decided to just ask.

-Joe

Hobbsmeerkat

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Early B.

Re: High Pass Filter
« Reply #18 on: 11 Apr 2022, 10:57 pm »
As many times as this question comes up you migkt want to make the link to the calculator a sticky

Yeah. On some other forums, they use a single sticky to provide links to some of the most asked questions. This could be one of them.

Today, someone asked about the maximum length of the wire from the servo subs to the amps. Danny has answered that question already, but it's buried somewhere in this forum. This sticky could provide the link to it.

Hobbsmeerkat

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Re: High Pass Filter
« Reply #19 on: 12 Apr 2022, 12:12 am »
Generally speaking the length needs to be 3-4 feet. The longer it gets the less effective the amp is at controlling the subs at higher frequencies.