Should all bass amps have a bass filter?

[JohnDaBass]

10 hours ago, BassTool said:

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

Perhaps someone would like to provide a scale to this parameter "Flubbyness" so that we could judge an amps suitability on its "Heft" and " Flubbyness". Us mere mortals could then assess which HPF gives the best Flubbyness control without any loss of Heft😂

[bartelby]

9 hours ago, Bill Fitzmaurice said:

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.

Here's some EQ curves I did a while ago for my Ashdown JJB-500. EQ set flat, except when I drop the 30Hz of course.

White noise in, DI to Focusrite interface and REW Software. 1/6 octave smoothing and 4 averages, not the smoothest of readings but gives the general idea. (obviously below 20Hz and about 20kHz is to be taken with a pinch of salt as those are outside the interface's freq range)

I was surprised just how much top end was cut just by engaging the flat EQ.

Edited September 24, 2018 by bartelby

[Phil Starr]

 My HA3500 is still my best sounding amp if a bit unreliable nowadays, and yes 30hz right the way down and 64Hz half way up with a bit of mid boost. A nicely judged graphic, but no HPF information as far as I can tell. 

[Chienmortbb]

1 hour ago, bartelby said:

Here's some EQ curves I did a while ago for my Ashdown JJB-500. EQ set flat, except when I drop the 30Hz of course.

White noise in, DI to Focusrite interface and REW Software. 1/6 octave smoothing and 4 averages, not the smoothest of readings but gives the general idea. (obviously below 20Hz and about 20kHz is to be taken with a pinch of salt as those are outside the interface's freq range)

I was surprised just how much top end was cut just by engaging the flat EQ.

There is a gentle slope with no EQ but not quite enough IMHO for a decent HPF. The 30Hz at -15dB is more like it but you are affecting the sound as the 100-150 region is also affected. This is where the old school, hump is usually found. A good HPF will leave the area above 70Hz untouched. However in Ashdown's defence  there is a degree of protection for speakers with that roll-off with the EQ switched off. Now if only they and others would ditch the deep or Sub switch.

Edited September 24, 2018 by Chienmortbb

[bartelby]

3 minutes ago, Chienmortbb said:

There is a gentle slope with no EQ but not quite enough IMHO for a decent HPF. The 30Hz at -15dB is more like it but you are affecting the sound as the 100-150 region is also affected. This is where the old school, hump is usually found. A good HPF will leave the area above 70Hz untouched. However in Ashdown's defence  there is a degree of protection for speakers with that roll-off with the EQ switched off. Now if only they and others would ditch the deep or Sub switch.

Yeah, with the EQ out there's no real HPF. The curves were more to see what happens when you cut 30Hz as much a possible. Obviously you can tweak the remaining frequency sliders to compensate, like Bill and Phil were talking about, to bring some of the useful range back. 

A good thing about the JJB-500 is there isn't the deep/sub control. It has a "harmonic emphasis" instead.

 

 

[Bill Fitzmaurice]

2 hours ago, Chienmortbb said:

 Now if only they and others would ditch the deep or Sub switch.

That depends on what it actually does. From a marketing standpoint a switch labeled deep or sub has value, but who knows what it actually does? The first piece of gear I had with a deep switch was a '65 Fender Bassman. One would naturally assume it was a low frequency boost. It was actually a high frequency cut.

[fleabag]

My old Ashdown Superfly had a graphic with a 40hz  slider ( i think it was 40hz - long time ago ) and i used to simply take that slider out, and rely on the rest of the graphic to get low end.  I really dont know whether that 40hz could be called a filter.

Same with my current Trace Mk 5 4x10 Combo.  40hz graphic bottomed

Edited September 24, 2018 by fleabag

[Chienmortbb]

2 hours ago, fleabag said:

My old Ashdown Superfly had a graphic with a 40hz  slider ( i think it was 40hz - long time ago ) and i used to simply take that slider out, and rely on the rest of the graphic to get low end.  I really dont know whether that 40hz could be called a filter.

Same with my current Trace Mk 5 4x10 Combo.  40hz graphic bottomed

 

3 hours ago, Bill Fitzmaurice said:

That depends on what it actually does. From a marketing standpoint a switch labeled deep or sub has value, but who knows what it actually does? The first piece of gear I had with a deep switch was a '65 Fender Bassman. One would naturally assume it was a low frequency boost. It was actually a high frequency cut.

Perhaps I should have said any type of boost below 100Hz that can be added to the existing preamp bass/low shelving, plus graphic/parametric EQ and sub bass/octavers that go an octave below. Not grammatically correct but hopefully clearer.

[EliasMooseblaster]

On 21/09/2018 at 18:03, Jack said:

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.

Out of curiosity, does anybody have a comparable EQ curve for a typical 100W tube bass amp? I hasten to add that I'm not trying to derail this into yet another valve-vs-SS debate, but in the same way that the bottles naturally compress the signal a little, I'd be interested to see what their frequency response is like.

[Phil Starr]

4 hours ago, EliasMooseblaster said:

Out of curiosity, does anybody have a comparable EQ curve for a typical 100W tube bass amp? I hasten to add that I'm not trying to derail this into yet another valve-vs-SS debate, but in the same way that the bottles naturally compress the signal a little, I'd be interested to see what their frequency response is like.

with a valve amp you have successive stages of the amp connected by capacitors, each of these would act as a 6dB/octave filter, most stages would filter at similar frequencies and this would determining the roll off of the amp. Most class AB solid state amps would have similar decoupling capacitors. In fact very few audio amps will go right down to DC. They pretty much all roll off the bottom end at some point. 

[Phil Starr]

12 hours ago, bartelby said:

Here's some EQ curves I did a while ago for my Ashdown JJB-500. EQ set flat, except when I drop the 30Hz of course.

White noise in, DI to Focusrite interface and REW Software. 1/6 octave smoothing and 4 averages, not the smoothest of readings but gives the general idea. (obviously below 20Hz and about 20kHz is to be taken with a pinch of salt as those are outside the interface's freq range)

I was surprised just how much top end was cut just by engaging the flat EQ.

That's really interesting, they've clearly chosen a roll off with a -3dB @ 40Hz which makes sense in terms of letting everything from bottom E upwards through. The roll off is about 12db/octave too. I'd go for your setting, lots of added warmth around the crucial octave 80-160 to boost the second harmonic and a roll off to clean out the mud and protect the speakers below40Hz. I also dial in a bit of extra 1-3kHz and roll off the top end.

There's potentially a lot of energy though below 40Hz which could threaten a lot of speakers if anyone became heavy handed with the bass boost.

[Gareth Hughes]

Acoustic Image have a user-friendly, defeatable and not-at-all hidden hpf on all of their heads. From a double-bass point of view this feature was indispensable. On recordings and onstage it could be set quite high, so cutting more out of the lows, and the result was a clear sound without the dull roar. I can see how that sounds like the opposite of what folks might think they want in an amp though.

Edited September 24, 2018 by Gareth Hughes

[MoJoKe]

Markbass don't tend to publish much technical detail on their amps as they are protective of their Mark Proprietary Technology branding.  Their call - I get that...

However, they DO have an inbuilt subsonic low pass filter.  It isn't and IMHO doesn't need to be switchable (and that goes for any bass amp thats designed well...  it shouldn't need to be).

I am happy to do some EQ curves after the weekend on a couple of different heads if people are interested.

Edited September 25, 2018 by MoJoKe

[bassace]

13 hours ago, Gareth Hughes said:

Acoustic Image have a user-friendly, defeatable and not-at-all hidden hpf on all of their heads. From a double-bass point of view this feature was indispensable. On recordings and onstage it could be set quite high, so cutting more out of the lows, and the result was a clear sound without the dull roar. I can see how that sounds like the opposite of what folks might think they want in an amp though.

Yes, although I don’t use an Acoustic Image with HPF anymore, I use an outboard usually set for 120-140Hz to bring out the best in the amp. And that’s with a 10” cab.

[Jack]

 

22 hours ago, EliasMooseblaster said:

Out of curiosity, does anybody have a comparable EQ curve for a typical 100W tube bass amp? I hasten to add that I'm not trying to derail this into yet another valve-vs-SS debate, but in the same way that the bottles naturally compress the signal a little, I'd be interested to see what their frequency response is like.

It seems that there's not a lot of graphs out there. I was able to find an RTA of a sansamp modelling a 300W SVT. Which is nothing like what you asked for but I suppose that it's a pretty good recreation of a pretty common tube amp?

 

So. No. Is the short answer.

 

 

 

 

[Ghost_Bass]

I would go as far as to say that a HPF is a must have in this day and age where almost everybody is going through the PA in pubs/etc.

It helps clean the stage sound and get better note definition / cut the mix without having to turn up a lot. I'm using a GB shuttle and it's internal HPF is in the sweet spot (i would say it's above the 30Hz of the Magellan). A variable HPF like in the Mesa Boogie Subway 800+ that can go all the way up to 80 or 70hz if needed would be a great and helpfull tool. Guitar amps shouldn't even be released without one! 😂

[Phil Starr]

8 hours ago, MoJoKe said:

Markbass don't tend to publish much technical detail on their amps as they are protective of their Mark Proprietary Technology branding.  Their call - I get that...

However, they DO have an inbuilt subsonic low pass filter.  It isn't and IMHO doesn't need to be switchable (and that goes for any bass amp thats designed well...  it shouldn't need to be).

I am happy to do some EQ curves after the weekend on a couple of different heads if people are interested.

Thanks for joining in. I tend to agree with you about no need to be switchable, why would you want stuff that you can only hear because it messes up the vocal mic's and sets off room resonances? Maybe that's just the sound engineer in me though.

Actually I really doubt that there are any bass specific amps out there that don't have some sort of filtering. It's pretty hard to design an amp where there isn't some need to decouple different sections of the chain to stop stray voltages getting through, even if that is only on the input from the bass. Just deciding on the size of the capacitor in each link means you have to have a design goal in mind before you do the calculation. It isn't really an option to switch that out of the circuit.

Anyway good to have you on board and if you can tempt Mark Bass or even Marco himself to comment.

Edited September 25, 2018 by Phil Starr

[Phil Starr]

2 hours ago, Jack said:

 

It seems that there's not a lot of graphs out there. I was able to find an RTA of a sansamp modelling a 300W SVT. Which is nothing like what you asked for but I suppose that it's a pretty good recreation of a pretty common tube amp?

 

So. No. Is the short answer.

 

 

 

 

Oh Look it's Bartleby's tone settings

 

[Chienmortbb]

On 23/09/2018 at 10:57, Woodinblack said:

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.

As i see it there is no need to go to 50Hz. 30 or 35Hz is ideal but the real thing is that the filter must be steep 18-24dB per octave.

[Jack]

5 hours ago, Phil Starr said:

Oh Look it's Bartleby's tone settings

Is that an old person joke?

[bartelby]

6 hours ago, Jack said:

Is that an old person joke?

😲 

you calling me old??

😂

[Al Krow]

3 hours ago, bartelby said:

😲

you calling me old??

😂

Or just a joke? 😂

[bartelby]

9 minutes ago, Al Krow said:

Or just a joke? 😂

😮

[Al Krow]

1 minute ago, bartelby said:

😮

Or worst of all, "both sir" 😂

Ok, I'm just getting my coat...

[markorbit]

On 25/09/2018 at 16:56, Ghost_Bass said:

I would go as far as to say that a HPF is a must have in this day and age where almost everybody is going through the PA in pubs/etc.

Guitar amps shouldn't even be released without one! 😂

Guitar amps should have them on by default and undefeatable. GET OUT OF THE BASS RANGE YOU PLANT POT !!! 🙂