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High Pass Filters


funkydoug

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37 minutes ago, PaulWarning said:

just had a look at my B1on and the para EQ goes down to 20Hz

But unless it goes into shelving mode at very low frequencies it won't act in the same way as a HPF. If you have a look at the plot posted earlier on in this thread you'll see that for a typical parametric EQ, you get a dip in volume at the selected frequency, but then the volumes increase again a you get further away from this point in each direction, so although it will be cutting the low frequencies it won't be cutting all of them and lower you go from the selected frequency the louder the signal gets again. Compare this with a HPF which progressively cuts the low frequencies from the selected frequency - which is what you want to remove sub-audible bass.

Having said that you might be able to achieve roughly what you want with the parametric EQ by setting the frequency considerably lower than you would a HPF and then applying a wide frequency range to that cut (Q control).

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I had a Hartke cab that rattled, turned out that a great big upholstery staple had somehow got attached to the tweeter magnet, so when played at loud volumes - in this case at a recording studio - it was enough to shake it off the magnet, only to be pulled back on again.

It was a shame we didn't find that at the studio, as the Ampeg cab I rented to replace it didn't sound as good

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22 minutes ago, BigRedX said:

But unless it goes into shelving mode at very low frequencies it won't act in the same way as a HPF. If you have a look at the plot posted earlier on in this thread you'll see that for a typical parametric EQ, you get a dip in volume at the selected frequency, but then the volumes increase again a you get further away from this point in each direction, so although it will be cutting the low frequencies it won't be cutting all of them and lower you go from the selected frequency the louder the signal gets again. Compare this with a HPF which progressively cuts the low frequencies from the selected frequency - which is what you want to remove sub-audible bass.

Having said that you might be able to achieve roughly what you want with the parametric EQ by setting the frequency considerably lower than you would a HPF and then applying a wide frequency range to that cut (Q control).

yep I get that, I was just saying it goes down to 20Hz I think someone earlier in the thread said another Zoom only went down to 40Hz, altough I think you could minmize that by stacking the Ba PEQ and using a high Q, still not the same as a HPF I agree

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The best option before spending any cash would be to find out if you are sending excessive sub-sonic frequencies to your speakers in the first place. You can do this relatively cheaply either with your computer or smartphone - you may need an audio interface too in some cases. I use a few free apps on my phone and either a Line6 Sonic Port or for other situations, a calibrated FRFR microphone.

Something to think about I guess! Also handy for testing the actual frequency response of a whole bunch of devices and components! Tone stacks to pickups, amp to pedals!

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On 31/01/2018 at 14:49, Jus Lukin said:

Well, are they rattling, or not?!

If they are it a) isn't imaginary, and b) shouldn't be happening!

Now I don't usually like to contradict you - 'cos you generally know a lot more about this stuff than me!  But on this one I think I'm right:

I've just tried the Yammy P-Bass with my Markbass combo (which is designed to handle 500W RMS) in a completely different room to my Mesa and VK cabs; and with the same settings as my other amps i.e. EQ on flat, the tone on the bass dialled down to be more sub-by and voila! Exactly the same outcome, the combo started rattling! Playing higher up the scale got a sympathetic vibration / rattle from the furniture, too. Dialling the bass EQ back on the amp and / or  increasing the tone to be more trebly on the bass both eliminated / reduced the rattle.

So I think I've got cause and effect right here - this is a hot Yammy pup issue and I already know that the following works to solve:

a) dialling the bass EQ back on the amps / increasing the tone EQ setting to make more trebly on the bass;

b) cutting the 50Hz by -12dB on the Zoom B3n GEQ (in the process established the single band PEQ on the B3n pretty much does zip, as kindly confirmed by Bartelby's charts)

Further things for me to check [updated for these]:

c) whether AC Bs Pre and the BA PEQ (dual band para EQ) on my Zoom MS-60B are as effective (or better) than the B3n GEQ; [ @Jus Lukinhas confirmed that the AC Bs Pre works well, particularly when stacked double. In fact he's gone on to stack FOUR of these in series to deliver a -48db cut in the shape of a KILLER HPF patch - see below in this thread; however for my purposes neither the AC Bs Pre or the BA PEQ were particularly effective and the MS-60B GEQ (as with the B3n GEQ) came out tops]

d) lower the heights of the pups below the strings. [Just made the bass significantly quieter than my other basses - they've been adjusted back up]

HOWEVER all of the above are reducing BOTH the desirable audible bass as well as the much less useful / energy sapping sub-audio frequencies

The whole point of looking for a cliff edge HPF solution is that I can eliminate the high energy sub audio frequencies which are part of what is making my cabs 'sweat' and leave the bass audio frequencies intact, which is kinda where this thread started (and particularly BigRed Xs early points on this in this thread). I guess this is just proving to be a 'live' case study! The HPF solution I'm guessing, will have wider application than on my Yammy bass and with my other basses and indeed drive pedals should allow me to boost the bass to compensate for low end without it becoming boomy.

I totally get your points that the Tech21 QStrip is limited by its lack of variable HPF / LPF and having an HPF that cuts everything below 45Hz (as well as larger footprint and cost!).

In my case an LPF is going to be welcome, too, if it can eliminate high end hiss which is e.g. present on my Markbass combo, as there is no possibility of adjusting the tweeter volume on that; and this high end 'fizz' is also present on a number of dirt pedals / digital dirt sims.

The Broughton, I agree, would appear to be the better answer.

Edited by Al Krow
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Oh and on the subject of using an EQ as an HPF, you’d benefit in this case in using a steep curve of 24dB/Oct as 12 can sometimes roll off too much of what you want to keep if the centre frequency is high.

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1 minute ago, dood said:

Having an adjustable HPF with a steep curve is also super useful before a compressor, especially full band versions :)

Interesting - please expand? Having been inspired by you to go for a mini board (even though it seems you have now abandoned this worthy venture!) and consequently now having limited space on my board, I was actually thinking of ditching my dedicated MXR compressor for a HPF / LPF pedal to take its place and making do with the Zoom MS-60B compressor effect sim.

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17 minutes ago, Al Krow said:

Interesting - please expand? Having been inspired by you to go for a mini board (even though it seems you have now abandoned this worthy venture!) and consequently now having limited space on my board, I was actually thinking of ditching my dedicated MXR compressor for a HPF / LPF pedal to take its place and making do with the Zoom MS-60B compressor effect sim.

But if you're using the MS-60B why add an extra HPF? It has one on board anyway...

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21 minutes ago, Al Krow said:

Interesting - please expand? Having been inspired by you to go for a mini board (even though it seems you have now abandoned this worthy venture!) and consequently now having limited space on my board, I was actually thinking of ditching my dedicated MXR compressor for a HPF / LPF pedal to take its place and making do with the Zoom MS-60B compressor effect sim.

I actually have to thank you for reminding me and that I am pleased to say that I am back to putting something together, though you'll be slightly shocked to hear that one of my TC's forgot it's settings the other day. :/ This doesn't bode well as I need 100% reliability in some of the work I do.

Ok, HPF - using a full band compressor as an example. - The threshold of a full band compressor is 'crossed'  by the largest area of signal passing through the circuit. For us bassists, that's pretty much always the low end. One of the downsides to this is that the top end can end up being masked as the low end is pulled down in signal (the top end goes with it). If you are driving excessive low end (especially sub sonic frequencies) in to your compressor then these frequencies could be overwhelming the threshold. Or to put it another way, sounds you can't hear are actually limiting the output volume of the ones you do want to hear. 

* I'll add this before I get jumped on by the compressor police: Some full band compressors use a side-chain filter to remove low end in the sensing circuit to alleviate this problem. Multiband compressors do not suffer either, but in either case, removing frequencies that are not going to be of any use in the signal chain isn't such a bad idea. Think I'm off to buy an HPF..lol 

Edited by dood
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my reading is a bit different to @CameronJ  - I think @Al Krow is saying all his cabs rattle with that bass plugged in.  

I would think it is very unlikely that all your affected cabs have the same resonant frequency (or close enough) or sensitivity to sub-bass so that they all rattle in the same way when a certain bass gets plugged in. Could it be that the rattle / fault is on the bass itself and is being amplified whatever it gets plugged into? Hard to say without hearing it.

I mean ... is the problem really sub-bass, or just a rattle on the bass or in the 'tronics?

Edited by funkydoug
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Just now, Bigwan said:

But if you're using the MS-60B why add an extra HPF? It has one on board anyway...

Has anyone tested the HPF on the MS? - (If I still had mine I would do that right now, but ... I don't anymore.)

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10 minutes ago, CameronJ said:

@Al Krow, it sounds to me as though the Yammy pups are simply exposing weaknesses in your Markbass rig 👀 If the issue is non-existent through your other rigs then the blame surely can’t be pointed at the Yamaha?

New rig o’clock? 🤔

Cam, buddy, you'll need to catch up with the thread! :P  It's a feature on all my rigs; the Markbass is just to confirm what was going on with the other rigs.

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Just now, dood said:

Has anyone tested the HPF on the MS? - (If I still had mine I would do that right now, but ... I don't anymore.)

Just through headphones via a little behringer desk so not really transferable to this case Dan...

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The MS-60B is one of the best value pedals currently available on the market. But it has limited processing power and it's a long way from the being the most 'user friendly' multi-fx in a live situation in terms of swapping in and out of patches. So if it's being used for another duty e.g. tremolo, chorus, delay or dirt on a particular song, then piling on a compressor and an HPF into a single combined 3 effects patch with each of the 'main' effects being used for the song, is going to be a big ask of it; and then having to get a set of bespoke duplicate patches for each bass depending on which is being used is going to be a pain.

This is where dedicated pedals come into their own...and I can see my PT Nano+ making way for a bigger brother pretty rapidly :)

 

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3 minutes ago, krispn said:

I think we’vetalked About the Cali76 cb before- great comp with variable hpf so the lows don’t trigger the comp too soon. See the Cali made sense all along

Lol! So there was me thinking my BC buddies had saved me cash by pointing out that a Broughton would make more sense than a Q-Strip; and now you're pointing out (correctly) the benefits of upgrading my MXR to a Cali!! Swings and roundabouts, eh?!

Hah! Cheapest answer would be to sell the Yammy 1025 and then fall back into my pre-HPF-thread ignorance :D:D The only (massive!) flaw in that is I can see the Yammy pretty quickly becoming a 'goto' gigging bass for me!

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6 minutes ago, Jus Lukin said:

Hey, no worries, man! It's a discussion after all, and I'm no genius! :)

It's all relative buddy, as Einstein (who knew a thing or two about being a genius) might have said :)

7 minutes ago, Jus Lukin said:

....the HPF seems good to me, although I do usually double them up for a steeper slope...Most of my default patches on the MS are a pair of HPFs followed by a comp, with one slot left if I want an 'effect' too!

I like the 'double HPF effects patch' suggestion a lot and I'll swap around the order so that it sits before the MXR comp on my board. If that works I might not need to get a Broughton at all. @Jus Lukin any reason you wouldn't go for a TRIPLE HPF effects patch on the Zoom?

Someone else was telling me that it's good to have the comp before an octaver (whereas I'd always thought it best to have the octaver at the start of the chain so it had the cleanest signal to latch onto; but I think that's not necessarily the case as the glitching, as DB pointed out, is typically caused by the octaver latching onto harmonics).

So methinks revised chain order is going to be HPF (i.e. Zoom MS-60B) --> MXR Comp --> T16 Octaver; that just leaves the Markbass Super Synth which I guess can go at the end of the chain?

 

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1 hour ago, CameronJ said:

@Al Krow, it sounds to me as though the Yammy pups are simply exposing weaknesses in your Markbass rig 👀 If the issue is non-existent through your other rigs then the blame surely can’t be pointed at the Yamaha?

New rig o’clock? 🤔

This!

Hot pickups do not make cabs rattle. Sending too much bass to cabs that can't handle it does. It's all about what's coming out of the speaker cable, if that's what you need to tame, you need to reduce bass and/or volume somewhere in the chain, and it makes most sense to do that with the amp controls, or a HPF. Setting up the bass to lower it's output will have the same effect as just reducing the gain on the amp. Why get your screwdrivers out when there's a knob for the job?

:dash1:

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