HPF / LPF question

[jacoby75]

Hey guys.
Forgive me if this is a stupid question. But me no think so good. Me has the dumbs. I’ve been experimenting with some pedals and I have a question about filters. If I put a HPF/LPF pedal at the front of my pedalboard, like the Spark Boost, will it still roll off frequencies below and above the cutoff points all of the way down the chain, or can ultra lows, for example, be reintroduced further down by other effects? In other words, do I have to put it at the end of the chain to ensure that it has its full effect on the frequencies?
Thanks

 

[yodedude2]

uhm. me dunno. good question. i would assume that an octaver or distortion could add frequencies after an hpf/lpf. end of chain sound like a good idea.

 

[jacoby75]

uhm. me dunno. good question. i would assume that an octaver or distortion could add frequencies after an hpf/lpf. end of chain sound like a good idea.

I suppose if you put the HPF in front of the octaver the octaver would still work if you, for example played a low E. But maybe if you put it after, and hit the low E octave, nothing would come out.

 

[yodedude2]

i would hope not

 

[mmbongo]

1) Once the frequencies are cut, they are cut. You can't bring them back. The closest you could get would be with an extreme EQ, something that boots like 48db or something outrageious like that but you would also be boosting a lot of other stuff so....no.

2) The Spark is not an HPF/LPF pedal.

 

[jacoby75]

1) Once the frequencies are cut, they are cut. You can't bring them back.

Thank you.

2) The Spark is not an HPF/LPF pedal.

True enough. Not a dedicated one at least. But when I was looking up other info about the pedal, it was noted that it has a 20/20 built in low and high pass filter. So I thought SOME of the same benefit may be indirectly obtained.

Thank you for the feedback.

 

[Mosfed]

I like em at the end. And yes you can reintroduce frequencies - for example I use a Sfx Microthumpinator a the start of my chain as a buffer and HPF. I find it helps my octave and synth pedals track better. For sure when I use the octave pedal, it is reintroducing frequencies below the HPF cut off that were cut.

 

[Mosfed]

1) Once the frequencies are cut, they are cut. You can't bring them back.

This is just not true. Any pitch pedal can bring back frequencies that were cut.

 

[jacoby75]

This is just not true. Any pitch pedal can bring back frequencies that were cut.

So by "pitch pedal" I'm guess that would mean an octave pedal, yes? What about things like my Tech21 VTBassDI or a speaker sim pedal? I think the speaker sim pedal (Digitech CabDryVr) is basically a filter anyway.

 

[jacoby75]

It probably wouldn't make sense to have it after my octave or wah pedals, as it may filter out frequencies that I'm trying to intentionally put in there. FWIW, here's a pic of my current setup. I was trying the TC Spark after the compressor, but might try it elsewhere. Maybe first so that even the compressor gets the cleanest signal to compress.

 

[Mosfed]

So by "pitch pedal" I'm guess that would mean an octave pedal, yes? What about things like my Tech21 VTBassDI or a speaker sim pedal? I think the speaker sim pedal (Digitech CabDryVr) is basically a filter anyway.

So octave pedals are one example of a pitch shifter but there are others as well. For the purpose of your question, we can limit the discussion to octaves like your Sub-n-up

I would still put your filter at the end - you aren’t taking out frequencies that you can really hear with a HPF. It’s more frequencies that muddy things up or really rock your speaker cabinets. I would get a filter that is adjustable so you can dial it into the rooms you are playing. I like having an HPF after my octaves - it keeps them from getting flabby and out of control.

 

[Stumbo]

So octave pedals are one example of a pitch shifter but there are others as well. For the purpose of your question, we can limit the discussion to octaves like your Sub-n-up

I would still put your filter at the end - you aren’t taking out frequencies that you can really hear with a HPF. It’s more frequencies that muddy things up or really rock your speaker cabinets. I would get a filter that is adjustable so you can dial it into the rooms you are playing. I like having an HPF after my octaves - it keeps them from getting flabby and out of control.

^This.

 

[ga_edwards]

True enough. Not a dedicated one at least. But when I was looking up other info about the pedal, it was noted that it has a 20/20 built in low and high pass filter. So I thought SOME of the same benefit may be indirectly obtained.

I can't find any info that specifies a built on hpf/lpf. However, if there is one and by 2-/20 you mean 20hz/20khz, I don't think you'll see any benefit of using this particular device as a hpf/lpf. 20hz-20khz is widely recognised as the limit of human hearing, and these limits aren't going to do much to protect your speakers and I highly doubt you'll notice any "tightening" effect on your tone. A higher hpf frequency is needed if this is your requirement.

I agree with the sentiments of having a hpf last. Other effects, not only pitch-shifting pedals, can add harmonic content that you don't necessarily hear but is there. This is often the stuff that desirable to cut to protect speakers, so having a hpf first is going to be pretty much redundant. To be honest, IMHO, the best place for such filters would be in the effects loop of your amp so that it also clamps down on your signal after passing through the amp's eq section.

 

[caeman]

If you cannot find a dedicated HPF or LPF pedal that you like, try using an EQ pedal for the same effect.

 

[jacoby75]

I would still put your filter at the end - you aren’t taking out frequencies that you can really hear with a HPF. It’s more frequencies that muddy things up or really rock your speaker cabinets. I would get a filter that is adjustable so you can dial it into the rooms you are playing. I like having an HPF after my octaves - it keeps them from getting flabby and out of control.

I don't use a speaker cabinet at this point. I have a direct-only setup, but I understand your point. From what I've seen from HPF's, the keep speakers from going bumpety-bump. There could still be some perceived benefit in an ampless setup, I'm sure. And an adjustable one would certainly be preferable. I was just curious about the Spark Boost having any effect with whatever baked in HPF/LPF it has. Which so far I've found none in that capacity.

I can't find any info that specifies a built on hpf/lpf. However, if there is one and by 2-/20 you mean 20hz/20khz, I don't think you'll see any benefit of using this particular device as a hpf/lpf. 20hz-20khz is widely recognised as the limit of human hearing, and these limits aren't going to do much to protect your speakers and I highly doubt you'll notice any "tightening" effect on your tone. A higher hpf frequency is needed if this is your requirement.

Yes, it was 20hz/20khz. I read it online in a forum called Music Tribe, I believe. After further reading about LPF/HPF, I have learned that I'd likely want something more around 30/1-3khz, most likely. I just didn't know if the 20/20 was enough to make any discernable difference and if that was what was accounting for the perceived improvement in my tone with using the Spark Boost.

I did try it at the end of my chain last night and found little to no difference with it on or off using my headphone/ampless rig. It does still make an improvement to me towards the beginning of my chain, though. I'm just not sure technically why. Maybe it's bumping just the right frequencies somewhere to make it stand out. I don't know. I set it for unity gain, add just a touch of the bass knob, and everything just sounds better.

Certainly a dedicated LPF/HPF would be better, like the Broughton unit. That may be in my future.

Thank you for the feedback.

 

[jacoby75]

FWIW, here is the info on the eq filters of the Spark Boost from Music Tribe:
Spark Booster: EQ specifications
Spark Booster: EQ specifications
Question:
I would like to know more details regarding the EQ of the Spark Booster.

Answer
Frequency ranges: (low cut, high roll off) 20Hz-20khz

Centre: 500Hz (means the middle value that you can then either go up or down from when moving the pots)
Bass boost/cut 125Hz
Treble boost/cut: 2kHz
The tone corrections work this way. The center point is "neutral" position. When you turn counter clockwise, either cut the frequency and when you turn clockwise, you boost the frequency. The Spark Booster filter reacts like a shelf filter with high and low pass filter for limiting frequencies outside the audible band. The center frequencies refers to frequency where the amplitude has dropped by -3dB. I attached a curve that makes you well understand.

To sum up, the two tone knobs act like shelf with the fixed frequencies of 125Hz and 2kHz plus you have a high pass filter set at 20 Hz and a low pass filter set at 20kHz.

The ‘Clean' setting means no equalization, just clean gain. The ‘Fat' setting fattens up your signal much like a 'Loudness' button on a stereo works. The Mid-boost section provides a bump in the mids to make guitar solos stand out. Unfortunately at the moment, I do not have the information about the gain of the filters but I think it should be +/- 15dB or 18dB, which is a standard.

Here are the Spark Booster features :

26 dB of clean boost.
Level knob - drive amps even harder.
Place after existing distortion/overdrive to enhance drive sounds.
Place before existing distortion/overdrive will increase the amount of distortion and sustain.
Add grit, life and compression to your tone.
Add body, punch and warmth to pickups.
Mid-boost - cut through any mix.
Active EQ - extended low and high end.
True bypass - optimal signal integrity.
The product page can be found here.

EQ diagram:

Spark_Booster_Filters.jpg

 

[Bassmike62]

I asked this question in another thread, but this is probably the best place: ca the Splitter effect seen on Zoom bass multis be used "sorta" like an HPF/LPF unit ?