Should all bass amps have a bass filter?

[Phil Starr]

I'm going to start a bit of a hare running with the hope that with the power of Basschat we can get some improved practice from the amp manufacturers. I'm not knocking them and I certainly don't want a slanging match from anyone, I'm hoping that people who monitor these pages like @Ashdown Engineering and @MoJoKe who has Mark Bass connections will all join in. If anyone can alert any other manufacturers it would be good to hear their opinions too.

Anyway the question is should all bass amps be built with an HPF that filters out subsonic bass, effectively like a Thumpinator but built in. Subsonic bass is only ever a bad thing, it damages speakers, sets off room resonances, get's picked up by every mic on stage and muddies the sound of your bass. In fact most bass amps (maybe all) just by their nature filter out bass below certain frequencies but most amp manufacturers don't tell you at what frequency or by how much. A switchable bass filter /HPF would be wonderful but just publishing some figures would help us all no end, it may be in most cases all we need is to see what the designers have provided for us.

So come on manufacturers, tell us what you've got.....    and how you can improve next years models

[Japhet]

Would be a great addition as long as it's adjustable and defeatable. An inbuilt noise gate wouldn't be a bad idea either in my opinion.

Edited September 20, 2018 by Japhet

[Chienmortbb]

In my opinion it is vital in a modern amp.

[Jack]

It didn't matter so much with a 100W tube amp into a cab that starts to roll off at 75Hz but nowadays we have 2000W of perfect, digital, clean power and cabs that go subwoofer low.

[Merton]

Yes. Perhaps a variable one, but if not then a Thumpinator-style HPF would be fine.

[Bill Fitzmaurice]

Most do have high pass filtering, you're just not aware of it. It would be seen on a chart of the amp voicing, but like most technical details other than watts you can't get them.

[BassBod]

Yep - my old SWR amps just about got away with it, but with increasing power comes more risk.  Keep it very low, variable etc but it’s just a good idea (especially with double bass and piezo pickups).

[Phil Starr]

6 minutes ago, Bill Fitzmaurice said:

Most do have high pass filtering, you're just not aware of it. It would be seen on a chart of the amp voicing, but like most technical details other than watts you can't get them.

Absolutely right, they'll all know what their amps do and it's useful information. Especially useful to anyone who pushed the envelope with fx , bass boost or who uses modern highly portable speakers. 

 

[Jimrs2k2]

Genz Benz  shuttle series all have HPF built in.

 

Jim.

[Osiris]

Around 18 months ago I bought a new Genzler Magellan 800 amp and was considering getting some sort of HPF to go with it, but before giving the credit card another good hiding I emailed Genzler to ask if the Magellan had any form of in built filtering. I very quickly received the following reply;

Yes, we do utilize a High Pass filter with the MG-800. It is a very steep slope and set low around the 30 Hz range. This allows us to achieve a clean, solid and authoritative low end without potential flubbyness. This also helps with protection from over-excursion for speakers under high power situations.

I hope this information is helpful.

Best Regards,

Jeff Genzler

There you have it, straight from the horse's mouth! And I can personally attest to the weight and power in the low end of the Magellan, it has depth to the lows but it is controlled and never overpowering. And neither do my speakers complain either. 

Agreed @Phil Starr I'd also like to see those amp manufacturers that have some sort of high pass filtering built in to their amps stating it in their marketing and on their spec sheets. 

 

 

 

Edited September 23, 2018 by Osiris

[Jack]

1 hour ago, Osiris said:

Agreed @Phil Starr I'd also like to see those amp manufacturers that have some sort of high pass filtering built in to their amps stating it in their marketing and on their spec sheets.

Unfortunately I don't think they will, the unwashed masses will see that it starts to taper off at 30Hz, say to themselves "but that means it'll have less low end" or maybe, "that means you won't hear my low b string" and they'll choose another amp over a Genzler.

[Woodinblack]

On 20/09/2018 at 16:17, Phil Starr said:

In fact most bass amps (maybe all) just by their nature filter out bass below certain frequencies but most amp manufacturers don't tell you at what frequency or by how much.

I agree with the idea of having a switchable low pass in an amp and the more amps that have it the better, but I would say that all bass amp manufacturers will say in their specs what frequency they filter, although as others have said, that will be viewed as a negative.

If you see a bass amp that specifies its -3db point at 50hz then people are going to avoid it. A switch would obviously be good. A frequency control would be even better.

[Osiris]

4 hours ago, Jack said:

Unfortunately I don't think they will, the unwashed masses will see that it starts to taper off at 30Hz, say to themselves "but that means it'll have less low end" or maybe, "that means you won't hear my low b string" and they'll choose another amp over a Genzler.

Unfortunately I think you are right, I'd overlooked the fact that there are some titanically stupid people about 

 

 

 

[Bill Fitzmaurice]

At last count 62,980,160 in the US. 🙄

Edited September 23, 2018 by Bill Fitzmaurice

[only4]

My Bergantino B-amp has a built in variable hpf, it’s adjustable between 30hz & 80hz in 2db increments 👍

Edited September 23, 2018 by only4

[Phil Starr]

6 hours ago, Jack said:

Unfortunately I don't think they will, the unwashed masses will see that it starts to taper off at 30Hz, say to themselves "but that means it'll have less low end" or maybe, "that means you won't hear my low b string" and they'll choose another amp over a Genzler.

 

1 hour ago, Osiris said:

Unfortunately I think you are right, I'd overlooked the fact that there are some titanically stupid people about 

 

 

 

These things go in cycles, people go crazy on something that is heavily advertised like 'servo amp', 'OFC cable' or 'damping factor' and then it all moves on. Genzlers idea of a 30Hz 24dB/octave filter is a great design feature. If they called it built in speaker protection we'd all want it. I'm sure it could be made a selling point if they so wanted. I suspect a few people reading this will already be thinking "oh the Magellan has a Thumpinator built in for free, I'll put that on the list". It may be that others are offering a similar 'free' feature but I didn't know about the Magellan and I don't know bout the others either.

I'm not necessarily expecting that this will be a headline figure, just that it is freely available in their sales literature and the amp's manual. Clever people will check the others won't notice unless it becomes a selling point.

[Phil Starr]

10 minutes ago, only4 said:

My Bergantino B-amp has a built in variable hpf, it’s adjustable between 30hz & 80hz in 2db increments 👍

So that's Berg and Genz. Any more we know about?

 

[BreadBin]

Hartke HA3500 - has HPF at 100hz and LPF at 10k with +/-18db on each.

[Osiris]

3 hours ago, Phil Starr said:

I'm not necessarily expecting that this will be a headline figure, just that it is freely available in their sales literature and the amp's manual. Clever people will check the others won't notice unless it becomes a selling point.

At the time I bought the amp, early last year, there was no mention of the HPF in the manual or on their website. I've not looked since so it may be that they have updated their marketing information. But in light of some of the above comments it may or may not be a wise move though 

[BassTool]

12 hours ago, Osiris said:

 This allows us to achieve a clean, solid and authoritative low end without potential flubbyness.  

 

 

 

One of the best adjectives I've seen on BC 🤣

[pete.young]

5 hours ago, Phil Starr said:

 

I suspect a few people reading this will already be thinking "oh the Magellan has a Thumpinator built in for free, I'll put that on the list". It may be that others are offering a similar 'free' feature but I didn't know about the Magellan and I don't know bout the others either.

 

I think you might have a reason to be deeply hacked off if you'd bought a Magellan, gone out and bought a Thumpinator and then discovered you could have saved yourself £120 .

[Jack]

5 hours ago, BreadBin said:

Hartke HA3500 - has HPF at 100hz and LPF at 10k with +/-18db on each.

They're normal equalisers aren't they?

[Dood]

6 minutes ago, Jack said:

They're normal equalisers aren't they?

Indeed. They are ‘shelving EQ’ types that I suspect will be 12dB/Oct at a guess. 

Edited September 23, 2018 by Dood

[Dood]

6 hours ago, Phil Starr said:

So that's Berg and Genz. Any more we know about?

 

I think I am right in saying EBS does and that the TD650 and HD350 were tweaked for “more low end” in the TD660 and HD360 respectively. I am unsure if the HPF was adjusted, but something in my mind makes me think that was part of the revoicing. TD650 being a superb and tight sounding amp. yum!

[Bill Fitzmaurice]

5 hours ago, BreadBin said:

Hartke HA3500 - has HPF at 100hz and LPF at 10k with +/-18db on each.

Those aren't low or high pass filters, or shelving either. They're band pass filters, centered at 100 and 10kHz. A high pass with a 100Hz knee wouldn't be all that useful, nor would a low pass with a 10kHz knee. When I had a 3500 I ran a bit of boost with the 100Hz filter, a bit of cut with with the 10kHz. I had the 30Hz all the way down or close to it, then the 64Hz up by 6dB or so to compensate for the effect the 30Hz filter had in the 45-50Hz range. Having the 30Hz slider down effectively made it a high pass.