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Adding a high pass filter to small combo

Jared Houseman

Jared Houseman

Jul 5, 2018
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793
#1
Would it be advisable to add a hpf between the amp and speaker of a small combo?

Like this one crossed at 80hz?
Invalid Link Removed

Right now I am using a rumble 15 and it has plenty of power for acoustic gigs. I want a better rig but don't currently have the budget for one. I figured $50 worth of upgrades would vastly improve the amp.

Will the hpf help tighten up the low end and lessen low end distortion? Will I be sacrificing anything significant?
 
#5
There are a couple of alarm bells, most notably the lack of a power rating. There are various good reasons why the right place for an HPF is before the amp, not between amp and speaker.

The trouble with upgrading an amp like the Rumble is that it will be less valuable modded than unmodified. I'd be inclined to leave it stock.
But if you want to upgrade it and aren't bothered about warranties and the like to my mind a better option would be a second hand 2*10, 1*12 or 1*15 8 ohm cabinet, and add a socket on the back to disconnect the internal speaker and connect to the external one. You'll be surprised how much more volume you'll get out of the 15W amp with a bigger speaker, and then when budget permits you can get another amp to power the larger speaker.
 
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#6
JimChjones said:
There are a couple of alarm bells, most notably the lack of a power rating. There are various good reasons why the right place for an HPF is before the amp, not between amp and speaker.

The trouble with upgrading an amp like the Rumble is that it will be less valuable modded than unmodified. I'd be inclined to leave it stock.
But if you want to upgrade it and aren't bothered about warranties and the like to my mind a better option would be a second hand 2*10, 1*12 or 1*15 8 ohm cabinet, and add a socket on the back to disconnect the internal speaker and connect to the external one. You'll be surprised how much more volume you'll get out of the 15W amp with a bigger speaker, and then when budget permits you can get another amp to power the larger speaker.
Click to expand...
I have better amps and cabs, I just don't have anything that beats the size and convince of the rumble. I want to get the most bang out of it's form factor that I can
 
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#8
In the Rumble Wiki, there are some speaker replacement stories on the 40, 75, and 100. Rave reviews in terms of tone and volume efficiency.

I haven't heard of anyone adding a fixed HPF to one, I know the v3 rumbles have one (fixed) built in, labeled "2nd order," but Fender won't tell us the frequency. :bored:

I was considering the 100c speaker upgrade but haven't decided if it's worth it. Good luck, I'll be watching!
 
#9
Passive crossover is designed around impedance curve of the driver.

Ported cabs have roller coaster impedance curve where you would want a ideal high pass for bass use.
so passive crossover wont work well at all

likewise 12dB rolloff is not ideal for subsonic filter.

there is plenty high pass filters on the market that are only 12 dB and yes you can waste money on them too.

80 hz probably be little to high and kill the bass.

subsonic filter be min 18dB and 24dB ideal
and again no one has bothered to design a passive high pass for subsonic protection. it would be done active.

The whole ajustable" thing is cool feature. but after recording bands, mixing live, mastering recordings, and using subsonic protection for subs.

i can tell you live on a channel with a direct signal from a bass player, or cleaning up a recording. usually a 24dB 30hz highpass will help any bass signal. 40hz at the highest if the player over EQs the krap outta his bass. thats it all done

high pass can help, but i suggest to not drink to much of the Kool Aid offered on talkbass. highpass can definitely help
but it wont be some mind blowing, gut wretching, ovewhelming life changing event for a rumble combo
 
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#11
I could be wrong, but I would imagine that a small combo like that would have high pass filter built into it. If you're trying to tone shape with a high pass filter and need/want to have high pass higher than what's baked in, that pedal would probably be the best answer.
 
#13
A passive filter like that on the output of the amp will do virtually nothing to improve the amp's performance and very little to improve the speaker's performance.

The HPF needs to be before the power amp and of sufficient slope and Q to be useful.
 
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#15
Broughton makes a great HPF/LPF combo that is IMO essential for live performance. It wont color your tone too much at relaxed settings. It can definitely save your night in a tough room. The addition of the LPF in the circuit really helps the unpleasant tones that a DI sends to the FOH but your cab wont necessarily produce...
 
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#16
Jared Houseman said:
Would it be advisable to add a hpf between the amp and speaker of a small combo?

Like this one crossed at 80hz?
Invalid Link Removed

Right now I am using a rumble 15 and it has plenty of power for acoustic gigs. I want a better rig but don't currently have the budget for one. I figured $50 worth of upgrades would vastly improve the amp.

Will the hpf help tighten up the low end and lessen low end distortion? Will I be sacrificing anything significant?
Click to expand...
Don't waste your money. If you had a lot of disposable income and at least a semi-pro rig jumping on the HPF bandwagon around here is fine and good.
But you play bass and your small bass combo was already frequency- limited at the factory to make it sound as good as it can in its tiny combo cab with the limited power and speakers available to it.

There are times when a HPF could be helpful, but for an electric bassist, for your Rumble 15 It will be a better use of cash to save for your next amp instead. You only have an 8 inch speaker. If you limit the low end anymore you're playing guitar.


I laughed out loud to read this thread! Someone on this site must be selling HPFs for a living
 
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#17
Rabidhamster said:
Don't waste your money. If you had a lot of disposable income and at least a semi-pro rig jumping on the HPF bandwagon around here is fine and good.
But you play bass and your small bass combo was already frequency- limited at the factory to make it sound as good as it can in its combo cab with the limited power and speakers available to it.

There are times when a HPF could be helpful, but for an electric bassist, for your Rumble 15 I believe it will be a better use of cash to save for your next amp instead. You only have an 8 inch speaker. If you limit the low end anymore you're playing guitar.


I laughed out loud to read this thread! Someone on this site must be selling HPFs for a living
Click to expand...

He makes a VERY good point. Combo amps are naturally a bit of a compromise on all fronts to make them convenient.

I reckon the HPF is more or less a hair-splitting topic for rigs that can really produce large amounts of low-end frequencies. So much that they are actually an issue in certain environments.

Thanks for bringing this one back to ground level!!
 
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#18
Jared Houseman said:
Would it be advisable to add a hpf between the amp and speaker of a small combo?

Like this one crossed at 80hz?
Invalid Link Removed

Right now I am using a rumble 15 and it has plenty of power for acoustic gigs. I want a better rig but don't currently have the budget for one. I figured $50 worth of upgrades would vastly improve the amp.

Will the hpf help tighten up the low end and lessen low end distortion? Will I be sacrificing anything significant?
Click to expand...


I've long been of the opinion that most entry-levelish combo's ARE high pass filters, LOL! :roflmao:
 
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#20
okcrum said:
Chances are, the low end response rolloff on a Rumble 15 is pretty close to that of the proposed crossover already. :thumbsup:
Click to expand...
maybe. Even if so a active filter would stop the amp from using up power on nothing.

seamonkey said:
Not every combo automatically needs a HPF. It's not like combo makers don't know how to add a filter before the amp to cut lows that the combo speaker can't reproduce. It may be of no benefit to add one. Save the money up for future gear.
Click to expand...
OP said it's distorting low notes. That to me says perhaps Rumble15 is not so advanced as to have its own HPF built in sufficient to cure beginners wailing on the low E at 11 or advanced acoustic gig players with no budget wanting to eke out a couple or 3dB without destroying their practice amp.
 

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