CurvyMama is a special preamp that will give flesh, curves and grain to harps or guitars …
It can fatten and overdrive tight sounding amps.
In that aim, it features an original tone control and a germanium output preamp.


curvymama, préampli correcteur pour harmonica

CurvyMama, Harp version

Main features

Adjustable gain to adapt the grain of overdrive to the mike.
Original tone circuit, improving the nuances
in the low medium and at the medium-treble junction..

  Midcut and phase invert switches.
  Output stage with germanium NOS transistors,
producing a mild and organic overdrive.

  High level low impedance output.

Listen to samples

Bandeau medium rouge - L15

 To order

1. Choose the version.
2. Specify a tone option.
3. Specify the shipping zone.
4. Click <Add to cart>.
5. Click ‘Cart’ on main menu, or keep on visiting.

Bandeau fin gris moyen - L15

curvymama mk2-0 version-harpCurvyMama
Harp version
Price down : 169 €

Preamp-corrector for harp,
as described on this page.
• 5 basic controls :
drive, bottom, biting, contour, volume.
• 2 switches : invert phase ; less mids
LikeYourFace, harp

Bandeau medium rouge - L15

Technical details

Universal input

• 200kΩ high impedance (who can do more can do less)…
• Ajustable level using gain control.

The input can be used with all usual microphones for harp.
• Antique piezo or ceramic “bullet” microphones (JT30, Green Bullet) …
• Old  high impedance dynamic microphones (Shure Control Magnetic, 545, 588) …
• Modern dynamic microphones, low level low impedance (SM57) …

Auxiliary controls
Invert Phase  Switch : phase inversion in order to minimize the risks of Larsen.
Less Mids Switch : 1,5kHz attenuator in case of a bullet mike too generous in mediums.

Tone controls

• Bandwidth and tone settings have been studied specifically for the harmonica.
• 3 controls : Bottom, Biting, Contour…

Bottom : the belly of the harp sound, at the junction of bass and low medium.
Biting : The global roundness or sharpness of the sound, according to the played styles.
Contour  : Carves symmetrically mediums and presence …

More precisions about CurvyMama’s tone controls

Overdrive stage

• The output preamp uses two NOS germanium transistors.
• The diagram is an adaptation of a classic circuit from the sisties.

• The overdrive is adjustable using the Gain control, from a clear sound to a fuzzy grain.
• In between, overdrive is progressive and organic, like coming from the heart of  sound.
•The tone controls are placed upstream and define the texture without washing it out.

Power supply

CurvyMama is powered by a 9V battery or an external 7 to 12V supply.
• Sound is typical with 9V, more dynamic with 12V, dirty and compressed with 7V.
• An internal electronic filtering eliminates common supply noises:
Hissing of switching power supplies, humming from transformer power supplies.
 Typical consumption with 9V: 8mA.

Like any germanium circuit, Curvymama gives its best sound after 5 to 10 minutes under power, when its internal temperatures have stabilized.

Bandeau medium rouge - L15

PCB of the 2018 prototype.

To know more…

Technical links

Technical sheet (downloadable pdf )

Clarifications concerning CurvyMama tone controls

Contact Guitar Poppa

Audio links

Listen to samples


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