Exceeding the "usable frequency range"

[Roland Rock]

I have a query that I was going to run past Alex Barefaced, but I guess he's busy with all this 3G stuff, so I thought I'd open it up to BC instead.

My cab has a "usable frequency range of 40Hz - 6KHz", and even though I play down to low b (31Hz) it still sounds immense. I gather this is because I'm hearing various harmonics and overtones rather than the fundamental note. No problems there.

I have ordered a low pass filter, as two of our songs are in a dub reggae style, and I'd like to get that pure deep deep tone. My understanding is that as you roll off the highs, you are basically eliminating all of these overtones and getting closer to the fundamental. You can then boost the frequencies around your chosen cutoff point.

So the question is, what happens if I boost a frequency below the "usable range"? Will I blow my speakers?

Edited September 26, 2013 by Roland Rock

[Bill Fitzmaurice]

[quote name='Roland Rock' timestamp='1380186581' post='2221909']
I have ordered a low pass filter, as two of our songs are in a dub reggae style, and I'd like to get that pure deep deep tone. [/quote]Just turn down the high and mid EQ on your amp.
[quote]So the question is, what happens if I boost a frequency below the "usable range"? Will I blow my speakers?
[/quote]Quite likely. The 'usable range' takes into consideration not only frequency response but also the driver excursion limit. Boosting below that range may result in over-excursion, causing both thermal and mechanical driver damage.

[Phil Starr]

Ok the usable frequencies are usually quoted to be the point where the sound drops by 6dB. If your speaker is ported, and most are nowadays, this will also be about the point where the bass port ceases to be effective.

Below this point you won't hear much bass but because the cabinet has effectively become just a box with a big hole in it the speaker is free to flap around, the excursion becomes so excessive that the coil will leave the magnet gap and probably start banging against the back of the magnet. This will eventually destroy the speaker depending upon how much you do it. So, the only effect of trying to go below this frequency will be to distort your sound and damage your speaker.

Below this point the power handling of your speaker will fall dramatically possibly to only a few tens of watts.

Yes you will blow your speakers.

The best way to protect them is to use a high pass filter, which will also clean up your sound.

You are right to think about cutting out the treble to get a bassier sound rather than trying to boost the bass with speakers that aren't capable of this, the only other way is to use massive power and speakers designed to handle these frequencies.

[chris_b]

What speaker cab(s) do you use?

Look up info on the SFX Thumpinator. That will save your speakers.

[shizznit]

I often play dub, reggae and ska and tens to roll off the treble and boost the mids a bit on my bass. I never touch the bass EQ on the bass or amp in danger of harming my speakers. If you use 10" or 12" speakers you have to respect their usaable range and more bass is not always the best approach

[Roland Rock]

[quote name='chris_b' timestamp='1380198144' post='2222163']
What speaker cab(s) do you use?

Look up info on the SFX Thumpinator. That will save your speakers.
[/quote]

It's a Barefaced '69er, the sealed 6x10
I'll look into a high pass filter. I think I'm going to have to be very cautious with this! Maybe I'll just keep it for lower volume recording

[Roland Rock]

[quote name='shizznit' timestamp='1380198395' post='2222169']
I often play dub, reggae and ska and tens to roll off the treble and boost the mids a bit on my bass. I never touch the bass EQ on the bass or amp in danger of harming my speakers. If you use 10" or 12" speakers you have to respect their usaable range and more bass is not always the best approach
[/quote]

That's what I am playing exclusively - dub, reggae and ska. I play with the highs and mids backed off and it sounds great. I just wanted a bit of that extra deep fundamental for these couple of tracks.
Thanks

[chris_b]

[quote name='Roland Rock' timestamp='1380199196' post='2222182']
....I think I'm going to have to be very cautious with this!....
[/quote]

I don't know why.

The Thumpinator will cut sub 30hz which the cab won't be able to reproduce anyway and reduce excessive cone movement. As far as I understand, you'll still get the full bass, via the harmonics, but won't risk the damage. I can't see a down side.

As you've got one of his cabs, I'd run this past Alex.

[Roland Rock]

[quote name='chris_b' timestamp='1380200080' post='2222207']


I don't know why.

The Thumpinator will cut sub 30hz which the cab won't be able to reproduce anyway and reduce excessive cone movement. As far as I understand, you'll still get the full bass, via the harmonics, but won't risk the damage. I can't see a down side.

As you've got one of his cabs, I'd run this past Alex.
[/quote]

Sorry, I meant cautious with the low pass filter solo. If I do go with the thumpinator, I'll feel a lot safer. I just need to decide whether I really want to spend even more on this whim, or get out altogether!

[Mr. Foxen]

[quote name='Roland Rock' timestamp='1380186581' post='2221909']
So the question is, what happens if I boost a frequency below the "usable range"? Will I blow my speakers?
[/quote]

Its the part where you ignore the speakers farting as you turn up that blows the speakers, rather than the frequency boost itself. You won't get very loud before that happens maybe. That rule 'if it sounds good, it is good' rule has a counterpart: 'if it sounds wrong, it is wrong'. Its lesser known and that's why I have a job fixing broken gear.

[Roland Rock]

I've just discovered something very interesting, considering one of my amps is a Streamliner 900. I was researching Thumpinator on BC, and this came up on the subject of high pass filters:

[quote name='pantherairsoft' timestamp='1379409629' post='2212217']
MB don't but Genz do (well, the Streamliner at least - I can't vouch for the Shuttle, but I imagine it's the same). I was sure my STM900 was cutting everything under 30hz as my cab goes that low quite happily and noticed a difference in floor movement. I spoke to one of the guys at Genz who designed it (he's actually a Talk Bass user too I found out after) and he confirmed it has a filter as part of it's circuitry.

That explained why I found the Thumpinator to be doing nothing for me! lol. I should try it again now with my Fafner... not that I actually want to filter out those lows, (my cabs drivers hardly move at the best of times and the amp doesn't break a sweat) but I would like to experience the Thumpinators effects properly.
[/quote]

[alexclaber]

The '69er is a sealed cab with a fairly high Q alignment so below about 100Hz its excursion limited power handling is basically constant at ~400W continuous, all the way down to about 20Hz (at which point leakage will start messing with the alignment). You won't hear much output below 40Hz but you'd be very unlucky (or silly!) to hurt it.

Edited September 26, 2013 by alexclaber

[Roland Rock]

Thanks for your replies all. With the combination of the sealed cab, the built in high pass filter and listening for signs of danger, I reckon I'll be fine.

[1970]

[quote name='Roland Rock' timestamp='1380186581' post='2221909']
So the question is, what happens if I boost a frequency below the "usable range"?
[/quote]

Brownsound.

[ShergoldSnickers]

Ideally, I'd like to see all amp manufacturers put a subsonic filter in by default, and have it switchable too. Might have to look at one of those Thumpinator jobbies, as the Eden WT550 I use doesn't filter out subsonics. The [url="http://www.sfxsound.co.uk/mainpage.asp?page=micro_thumpinator"]micro-Thumpinator[/url] looks good.

[Guest bassman7755]

[quote name='Roland Rock' timestamp='1380186581' post='2221909']
I have a query that I was going to run past Alex Barefaced, but I guess he's busy with all this 3G stuff, so I thought I'd open it up to BC instead.

My cab has a "usable frequency range of 40Hz - 6KHz", and even though I play down to low b (31Hz) it still sounds immense. I gather this is because I'm hearing various harmonics and overtones rather than the fundamental note. No problems there.
[/quote]

IMO pretty much anything you hear as a recognizable note will be overtones from the bottom E of a bass downwards and the fundamental will be more "felt" than "heard".

[chris_b]

[quote name='Roland Rock' timestamp='1380205002' post='2222295']
....With the combination of the sealed cab, the built in high pass filter and listening for signs of danger, I reckon I'll be fine....
[/quote]

What amp are you using?

[Roland Rock]

[quote name='chris_b' timestamp='1380214953' post='2222461']


What amp are you using?
[/quote]
The Streamliner 900. It was your suggestion of the Thumpinator which led me to research it, and I came across the info in post 11. Thanks!

I also use a valve amp, but could easily get by only using the LPF with the Streamliner

Edited September 26, 2013 by Roland Rock

[Bill Fitzmaurice]

[quote name='Roland Rock' timestamp='1380204281' post='2222279']
I've just discovered something very interesting, considering one of my amps is a Streamliner 900. I was researching Thumpinator on BC, and this came up on the subject of high pass filters:
[/quote]Many amps incorporate HP filters, it greatly reduces warranty claims on blown drivers.

[Phil Starr]

[quote name='Bill Fitzmaurice' timestamp='1380232030' post='2222736']
Many amps incorporate HP filters, it greatly reduces warranty claims on blown drivers.
[/quote]

Quite right, with the almost wholesale use of ported speakers the only surprising thing is that switchable filters aren't incorporated into all bass amps. They are widespread in PA amps and in mixing desks. We know exactly what happens when you don't have them so missing them out is half-assed engineering on the part of the amp designers.

The idea that manufacturers are putting out ported speakers with 3mm xmax drivers and claiming 600W handling, then making amps with 600W outputs down to 20Hz, incorporating 18dB of bass boost and selling them to people with 5 string basses and no technical training seems pretty cynical to me. Probably the triumph of marketing over sound craftsmanship.