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High Pass Filter (HPF) and Low Pass Filter (LPF) Mega Thread

#222
Ok, so I'm planning on getting the DSM Omnicabsim and running that thru my amps FX loop (Darkglass 900) and using that as my XLR, however I keep seeing mention of the benefits to running a HPF *before* effects and the benefits.

Is there a HPF on the market that can be used as a looper where you can blend back in the unaffected lows(since I plan on running it through both a HP/LP at the end with the DSM)??? Or is this just a crazy idea?? Pointless and unnecessary??

Apologies, this is a whole new thing to me...also I'm running through a fEARful cab so I get a pretty accurate representation of the FOH tone(if that helps??)

I'm hoping the HPF will make my OC2, filter, drive and chorus all react even better
 
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#223
hintz said:
Ok, so I'm planning on getting the DSM Omnicabsim and running that thru my amps FX loop (Darkglass 900) and using that as my XLR, however I keep seeing mention of the benefits to running a HPF *before* effects and the benefits.

Is there a HPF on the market that can be used as a looper where you can blend back in the unaffected lows(since I plan on running it through both a HP/LP at the end with the DSM)??? Or is this just a crazy idea?? Pointless and unnecessary??

Apologies, this is a whole new thing to me...also I'm running through a fEARful cab so I get a pretty accurate representation of the FOH tone(if that helps??)

I'm hoping the HPF will make my OC2, filter, drive and chorus all react even better
Click to expand...
You may want to check with the Effects Forum and let us know how it works out.
HPF added to looper with clean blend?
 
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#224
I almost ALWAYS use a HPF on Acoustic instruments. Let's just say ALWAYS for acoustics.
Acoustic Guitars too. Nothing worse than a 6 string acoustic guitar Thumping deeper than a bass drum.. That's a MESS.

But Electric bass, I prefer to let it go AS IS, and just let the AMP that i select for that gig do the EQing .. Newer amps seem to all be pre HPF..
(edit) Its why still use my API 512 pre on some gigs. Its Fat, Wide and Fast... Or even my old 70s Alembic F2B that i have grown very fond of.. Not a great amount of EQ. BUT it has a synergetic beauty when used with a certain bass and cab..
 
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#225
Stumbo said:
You may want to check with the Effects Forum and let us know how it works out.
HPF added to looper with clean blend?
Click to expand...

I just found that after I posted here, LOL!! Thank you though, if that's the same post it seemed inconclusive as to whether something like this was made or not? Then again it gave me the simple idea to simply run a HPF in the blend loop so I might try that
 
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#226
hintz said:
Ok, so I'm planning on getting the DSM Omnicabsim and running that thru my amps FX loop (Darkglass 900) and using that as my XLR, however I keep seeing mention of the benefits to running a HPF *before* effects and the benefits.

Is there a HPF on the market that can be used as a looper where you can blend back in the unaffected lows(since I plan on running it through both a HP/LP at the end with the DSM)??? Or is this just a crazy idea?? Pointless and unnecessary??

Apologies, this is a whole new thing to me...also I'm running through a fEARful cab so I get a pretty accurate representation of the FOH tone(if that helps??)

I'm hoping the HPF will make my OC2, filter, drive and chorus all react even better
Click to expand...

Generally, you do not want a parallel path around the HPF. The phase response of the filter at the knee can do some bad things to the smoothness and uniformity of the response.

IN DSP, it's possible (not common) to create a filter without the phase response issues (takes different algorithms) but that's the exception to the rule.
 
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#227
agedhorse said:
Generally, you do not want a parallel path around the HPF. The phase response of the filter at the knee can do some bad things to the smoothness and uniformity of the response.

IN DSP, it's possible (not common) to create a filter without the phase response issues (takes different algorithms) but that's the exception to the rule.
Click to expand...

Noted, thanks so much!! I will take your word on this.... though I think I'm still missin something?

I might scratch that idea and just run both at the end, I got more reading to do I guess??
 
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#228
Passinwind said:
And finally, a little bit of shameless self promotion: I have hopes that someone here will take the lead on an open source HPF project along these lines, which coincidentally happens to feature a variable LPF section, albeit in a different format from what we'd typically be talking about in this thread. I just may do that eventually if no one else steps up, but my plate is currently quite full and I still have a lot of fleshing out to do on the builder's WIKI for the current project.
Click to expand...

Somebody? Anybody?! Please!!!! Would love something like this!
 
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#229
hintz said:
Noted, thanks so much!! I will take your word on this.... though I think I'm still missin something?

I might scratch that idea and just run both at the end, I got more reading to do I guess??
Click to expand...

As an example, when you add one signal that is phase shifted exactly 180 degrees over part of it's range with a signal that is not phase shifted, you will get a subtraction of the larger signal from the smaller signal at that range. If the levels are the same, they will drop out entirely. There is a lot of phase shift with higher order active filters, sometimes not quite what you might expect.
 
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#233
In the meantime ... there's lots of talk here about d-class amps (versus, presumably some other class, or versus all other classes). Now ... I have a vague understanding that the class of amp is due to the internal architecture of power transistors / power tubes (?) but I have no clue how that relates to the discussion of sub 40 Hz frequencies escaping from the amp into the speaker ... which is what this thread is all about right ?

So can someone please explain for me why the class of amp is relevant ?
 
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#234
RandM said:
Bye the Bye - may have missed this, does the Subway Pre Amp/ DI haved a HPF in there AgedHorse?

Maurie.
Click to expand...
From the manual:
"While not a visible switch or control, it is an important internal feature in maintaining control over the extreme low end, especially under high drive conditions. This precision 4 pole filter has a turnover frequency that is set at approximately 30Hz with minimal ripple response. While HPF's have been standard fare within the pro audio industry for decades, this feature has only appeared in bass guitar amplifiers within the past few years (with a few exceptions). this filter also provides additional mechanical protection to the speakers by limiting the power to the speakers below the frequency range that the speaker cabinet cannot provide adequate acoustic loading to the drivers. This is one of the primary (and preventable) causes of premature speaker failure, especially with compact speaker cabinet products."
 
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#238
BigBeatNut said:
In the meantime ... there's lots of talk here about d-class amps (versus, presumably some other class, or versus all other classes). Now ... I have a vague understanding that the class of amp is due to the internal architecture of power transistors / power tubes (?) but I have no clue how that relates to the discussion of sub 40 Hz frequencies escaping from the amp into the speaker ... which is what this thread is all about right ?

So can someone please explain for me why the class of amp is relevant ?
Click to expand...
The relevance is most probably because class D amps are becoming higher powered which jeopardizes speakers more at the lowest frequencies.
 
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#239
BigBeatNut said:
In the meantime ... there's lots of talk here about d-class amps (versus, presumably some other class, or versus all other classes). Now ... I have a vague understanding that the class of amp is due to the internal architecture of power transistors / power tubes (?) but I have no clue how that relates to the discussion of sub 40 Hz frequencies escaping from the amp into the speaker ... which is what this thread is all about right ?

So can someone please explain for me why the class of amp is relevant ?
Click to expand...
Thread drift.
 
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