Adding a high pass filter to small combo

[JimmyM]

80 is too high as far as I'm concerned. Even Jamerson's Motown tracks were high passed at 70, but only because they were afraid mixing the bass that hot would make needles jump out of the grooves if they didn't, and that's too high for me as well. 60 I can deal with. But on a small combo? Nah.

 

[Rabidhamster]

maybe. Even if so a active filter would stop the amp from using up power on nothing.

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.

It's only a 15 watt amp with one tiny speaker of course it's distorting low notes it's only intended for beginners to play in their bedrooms.

 

[Downunderwonder]

It's only a 15 watt amp with one tiny speaker of course it's distorting low notes it's only intended for beginners to play in their bedrooms.

And that is of course what can be averted with a HPF. What's so hard to accept about OP's lack of budget to do anything else?

 

[Mingo Sanders]

Would it be advisable to add a hpf between the amp and speaker of a small combo?

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

You don't have your bass entered in your profile. I'm not being a smartass, but what have you tried so far in terms of using the tone controls on your bass and your amp to get the tone (and volume) you're looking for?

I wouldn't try modifications to a small combo, even the inexpensive mod you're considering. I saw that you started another thread asking about a lightweight 1x10. Go look in the classifieds and check used gear in your local area. If you can, play your bass into anything you're considering, and spend some time working with the tone controls.

 

[JimChjones]

What's so hard to accept about OP's lack of budget to do anything else?

But given lack of budget its best to be damned sure you're spending it wisely. This is an especially unsophisticated HPF and its not obvious it will do much that's different to just backing the bass knob off a bit. Without specs for the amp its difficult to be sure. If a post amp HPF were generally a good thing we'd see them regularly, but we don't, and the reason is its cheaper, easier and more effective to put these things in the preamp. Fender were putting HPFs in some of their bass amps in the early 90s - my BXR300 had one - so they do know how to do it.

 

[Downunderwonder]

But given lack of budget its best to be damned sure you're spending it wisely. This is an especially unsophisticated HPF and its not obvious it will do much that's different to just backing the bass knob off a bit. Without specs for the amp its difficult to be sure. If a post amp HPF were generally a good thing we'd see them regularly, but we don't, and the reason is its cheaper, easier and more effective to put these things in the preamp. Fender were putting HPFs in some of their bass amps in the early 90s - my BXR300 had one - so they do know how to do it.

Active HPF on the instrument signal or fx loop ftw. Fdeck HPF3 schematic freely available.

 

[beans-on-toast]

You want a HPF at the input of the amp, not on the speaker. Better if it's variable. By treating the signal at the input, you won't be slamming the preamp with content that you don't need. This is better to the tone stage performance.

 

[Jared Houseman]

If money is tight but you have soldering skills you can build the fdeck HPF3 off the free plans. It might be $20 worth of bits and bobs at most.

Could you point me twords the plans? I didn't know they were available

 

[Luckydog]

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.

IMO, this is all you need to know. Short and to the point!

 

[Rabidhamster]

Would it be advisable to add a hpf between the amp and speaker of a small combo?

Like this one crossed at 80hz?
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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?

Id recommend considering spending the time and energy your use on building a HPF, on a side hustle to get the cash for a bigger amp. You don't need much more cash plus your current amp to get to the next step up.
If you're not 18 you can often still buy things cheap in pawn shops with cash and you forgot your ID.

Cutting the low lows out of a budget amp would help slightly, if you know with certainty it wasn't already done. It may also be something you can use in the future, but in my opinion you're so close to a huge step up I'd personally rethink this route for now, perhaps revisit it. A good HPF does smooth out slap runs a lot on big amps.

 

[Balog]

Could you point me twords the plans? I didn't know they were available

Technical & DIY Stuff - hpftechllc

 

[JimChjones]

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

If you prize the Rumble for form factor but want a significant improvement in sound quality with the same portability and lack of bulk then I suspect you may need to look a fair way up market.

 

[Downunderwonder]

OP said he has ''plenty of power'' and wanted to tidy up the low end.

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[agedhorse]

OP said he has ''plenty of power'' and wanted to tidy up the low end.

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Perhaps he thinks he has plenty of power, but in fact part of the problem is the low powered amp only appears to have enough power but it's not able to control the speaker, especially if it's clipping the power amp which can cause a mushy low end. Also, speakers that are efficient often do not have great low end control or definition.

 

[Downunderwonder]

...and by adding an HPF to his input he can double down on the ''AM radio'' sound of his tinpot acoustic rig while not wasting any power at all on the useless low part of his signal.

 

[JimChjones]

Its a question of balance. If i turn the bass tine knob down to zero than i have a particularly brutal hpf, and have trebled down on am radio sound without wasting any power on the low part of the signal, but i may not like the resulting tone much.

My concern is Fender have probably done all they can within budgetary limitations to optimise performance in the Rumble range, and as its well regarded have probably done a pretty fair job. I think there are unlikely to be cheap improvements unless you are willing to make a big compromise in some aspect. Having said that a front end hpf is a useful tool, and well worth making, but don't expect too much.

Ive been mulling over micro amps myself. There's an 8in faital driver that has some promising specs, as we've discussed elsewhere, but my conclusion is it really needs to go in a 1*10 sized enclosure, in which it would probably deliver a reasonable bottom end at the price of a lot of volume, and thus need a considerably more powerful amp to deliver the same db as a 15w fender.

 

[Downunderwonder]

Fender have probably done all they can within budgetary limitations to optimise performance

if I was Fender I would make it sound boomfy as possible at practice volume. OP identified too much low end distorting low notes. That's two data points in favour of adding an HPF. Who seriously expects Fender to produce a practice amp that goes to 11 without distorting?

 

[agedhorse]

Since I am familiar with this combo, quite familiar, and my comments were based on this familiarity.

An HPF at the input may help a little, at the speaker out won't help at all, but ultimately the amp is the wrong tool for the job imo and IME.