Ultrabass, psychoacoutstic low bass for little speakers

[sofaspud]

Then there's this blast from the past...

[danielwritesbac]

Originally Posted by sofaspud

Then there's this blast from the past...

And backwards. . . That's a harmonic divider to increase x-max. But, I need the opposite device to decrease x-max for 3" and 4" speakers with 1mm clearance.

The device I'm looking for is psycho-acoustic bass with the low fundamentals omitted--This has low bass sound of headphones--very pretty but no impact, and thus no x-max either.


P.S.
Ah, fond memories of the DBX and a club with a vibrating wooden floor where the drinks were cheap and all the tail was free, but then I got married and have 3" to 4" speakers that I might could use in the garage or garden. Wow, just like bait-n-switch marketing!! Anyway, need odd multiplier, not even divider.

[rcw666]

I would try a low pass filter and a full wave rectifier and mix this with the other sound via another low pass filter.
You could probably do the whole thing with a quad op amp.
rcw

[rcw666]

This is something like the thing I would knock up...
rcw

[Wavebourn]

The secret weapon of such "ultra-bass" is saturating transformer. Audio engineers who record music for ipods and similar toys know this well.

[sofaspud]

Interesting... I'd never heard about that secret weapon.

And just to clarify, the above device isn't so much a divider. It was designed to generate tones an octave lower than the actual signal (of between about 50-100Hz) and add them at the output. An idea before its time?
That is the opposite of what you're looking for, so if a similar device subtracted instead of added...

[rcw666]

That's what the device I described does.

It full wave rectifies the input from the first low pass filter to produce the second harmonic plus a lot of other harmonics, then filters out the higher harmonics this produces and adds them to the original signal.
Saturating a transformer gives third harmonic only whereas this gives both second and third, the balance of which is dependent upon the roll of point of the output filter.
rcw

[danielwritesbac]

Originally Posted by rcw666

I would try a low pass filter and a full wave rectifier and mix this with the other sound via another low pass filter.
You could probably do the whole thing with a quad op amp.
rcw

Originally Posted by rcw666

This is something like the thing I would knock up...
rcw

I didn't understand this schematic because the hookup for the 2 pins of the single diode shown, is not the same as the 4 pins of a full wave rectifier.
How does that go?

[phase_accurate]

The one function that showed the best result according to the AES articel was some exponential with an offset. From the complexity point-of-view this shouldn't be difficult to be done in analog circuitry. The enemies (as always when doing tricks with nonlinear analog circuits) are component tolarances and thermal runaway.

I will have a look at the paper again and will show a circuit that could be used but I will not do any fine-tuning etc.

The full-wave rectifier wasn't perceived as being too good in the JAES article.

Regards

Charles

[rcw666]

The diode only lets positive going signals in, when this happens there is feedback the negative going signals go via the input and feedback resistors, in this case there is no feedback until the op amp output goes positive again.

This is about the simplest precision full wave rectifier you can make.
rcw