Qualitative variable bass humps – digital EQ v alignment, freedom from compression

[rick57]

To add mid bass/ boost, up to say 4 – 6 dB to cover baffle step loss and a little boost for warmth~energy, AFAIK (I’ve only started thinking of bass boost in the last week) there are two ways, EQ and box alignment . .

Some have implemented *variable box sizes, by sliding panels, eg the Aspen kits (sold by Aksa amps) used this idea to tune to a room, and GM recently suggested to me a vent using the floor as it’s bottom, and varying the spacing off the floor.

OTOH, a buddy with more knowledge than me, suggesting building a flat alignment, and playing with EQ. More flexible, but how to implement without components degrading the sound?

For digital sources, you could take digital out, put it through a digital parametric EQ (then into DAC, etc). A Behringer would be cheap, but that would likely reflect in parts quality, and maybe sound quality . .


* My basic question is, assuming the driver efficiency & amp power has enough capability to handle the boost from the EQ option, and the boost obtained was of the same level, would there be qualitative differences between the two methods?

If the driver was pushed harder, thermal and compression issues would come in, and the box size that gave the boost might be a better option.
OTOH, if you’re using good ‘pro’ drivers (high efficiency, high power handling) and plenty of watts, in domestic situations I would think there would not be much compression unless you’re annoying your neighbours . .

I’m beginning to convince myself of the digital parametric EQ option, with a modest boost from the alignment.

Anyone care to share their experience?

Thanks

[PeteMcK]

Baxandall tone controls work fine for me, using ~ 3dB boost on cabs with EBS alignments;
The problem with them is that usually the turnover point is 1KHz, which is too high, Rod Elliots trick of using ~250Hz gets the boost where it's needed.

Pete McK

[MJL21193]

This would be cheaper to do with crossover tuning, baffle step correction and an L-pad on your tweeter (I assume it's two way). Once it all sounds neat, turn up the volume

[terry j]

rick I muck around with the deqx, so changes on the fly are as easy as you would want.

I regularly, and without a second thought, put a boost in the midrange to achieve the results I want. In the midrange, it is often to gently bring the vocals out a bit (all dependent on the recording of course) and so I throw in a 2,3 or whatever db boost, usually around 800 hz or so about 2 octaves wide.

Anyway, the actual figures aren't important, but yes I do not think twice about it. I'm certainly no expert, so others may correct me here, but in the higher frequencies I don't think boost is problematical, whereas in the bass region you need to approach boost with a little more care perhaps.

Strangely enough I have asked this question today on another forum, except I wonder about it with a sub. Flat FR (obtained by whatever method) but different box sizes to give a different Q, how different do they sound. You are asking a similar question but seem curious about mid range frequencies.

I too will be interested in the responses that may come.

[rick57]

Pete,
Yes 1KHz is high, I’m thinking of 80-250 Hz
What’s Rod Elliot’s trick and its range?

Cheers

[rick57]

MJL,

Yes it would be cheaper with baffle step correction etc

Though I'm looking to understand the trade-offs in the more effortless/ less compressed route (arising from alignment peak, rather than entirely from BSC) and/ or more flexible options, or whether my ideas are flawed.

Cheers

[rick57]

Terry,

The deqx would be great by all reports, were I to win Lotto .

A boost to gently bring vocals out wasn't my intent but (recording dependent) would be one of the possible nice bonuses of the EQ route.

My interest is focused on mid bass, say 80 - 350 Hz, which has the most energy and I see as the "engine room" of pop/ rock

Though I've heard that some (all?) digital EQs intended for pro-audio use, are not compatible with some transports ~ anyone which or in particular how to determine, other than buy & try?

Cheers