Thiel Driver, Cumulus Horn

Cumulus-Horn from Hobby HiFi 6/2005 - with absolute three-dimensionality

Technical data:
- Impedance: 4 Ohm
- nominal SPL (2.83V/1m): 88 dB
- size (HxWxD): 117.5 x 24.8 x 500 cm
- frequency range (-8dB): 45-34 000 Hz
- frequency range (-3dB): 48-33 000 Hz
- crossover frequency: 1850 Hz
- speaker type: hyperbolic horn

In addition to the Cumulus projects in Hobby HiFi 5/2005 the readers requested a design where the Thiel driver works on its own. There is in fact already the Cumulus Satellite with just the Thiel (as well as in the One Point Monitor, featured in Klang+Ton 6/05), but a design where the Thiel on its own is also responsible for bass was still missing: therefore, Bernd Timmermanns developed a large bass horn.

How Bernd Timmermanns proceeded and what's important in the design is described in issue 6/2005.

Review of the horn by Hobby HiFi 6/2005:

..."Then the slim and yet mighty horns played like raging elements as if they were coming from a different planet. It started off with the ringing of the Gütersloh bells to be found on the fantastic Manger test CD. The belfry grew in the listening room to it's full width and depth, even the full height seemed to be present, though this is actually physically impossible. And these bells displayed their mighty bodies in a way never to be experienced before. Next on the agenda was Hermann Prey: entirely three-dimensional, standing with considerable distance in front of the accompanying piano. And the piano itself: also entirely three-dimensional, although difficult to portray the instrument is placed relatively far in the background. This profound three-dimensionality is a rare experience. It doesn't matter whether the rich, warm and yet clearly depicted tone is responsible, or two positive properties that are isolated from one another: this is great."... Thiel Koinzidenzwandler

and the verdict by Hobby HiFi 6/2006

"The Cumulus horn plays in a different league. Even though the typical horn characteristics prevent them from being quite close to reality: liveliness and three-dimensionality are of the highest standard. This thrilling performance, dragging every listener into the wake of music, is impressive. This is a rare experience. Each one of the 3.000 Euro spent on the material of a pair of Cumulus horn is a wisely invested."

Description of the Thiel driver

Jim Thiel / USA - not to be mixed up with Bernhard Thiel/Accuton whose products we sell as well - developed a wonderful coincidentally mounted driver (coincident source array) that encouraged us to offer top quality drivers coming from the finished loudspeaker market. The inherent problem of multiple drivers mounted side by side or one behind the other (coax drivers) is the lack of precise imaging. This kit suggests a coincident source driver that is time and phase coherent regarding low and high frequencies.

The standard kit contains:
- 1x Thiel coincidentally mounted driver, unshielded
- 1x polyester fleece
- 0.5x foam sealing tape
- 6 x Allen screws 4x16 mm
- 2x terminals
- 4 m Spirit of HighSilver cable, 2x2.5 mm²
- building instruction

- 3x epoxy glass fibre universal PCB
205 x 140 for mounting the following components:
- 1x 0.56 mH baked varnish coil 1.4 mm
- 1x 1.5 mH baked varnish coil 1.4 mm
- 1x 0.47 mH baked varnish coil 1.4 mm
- 1x 0.27 mH baked varnish coil 0.7 mm
- 1x 0.33 mH baked varnish coil 0.7 mm
- 1x 0.022 mH baked varnish coil 0.7 mm
- 1x 2.7 mH baked varnish coil 0.7 mm

- 1x 0.56 mH baked varnish coil 1.4 mm
- 1x 1.5 mH baked varnish coil 1.4 mm
- 1x 0.47 mH baked varnish coil 1.4 mm
- 1x 0.27 mH baked varnish coil 0.7 mm
- 1x 0.33 mH baked varnish coil 0.7 mm
- 1x 0.022 mH baked varnish coil 0.7 mm
- 1x 2.7 mH baked varnish coil 0.7 mm
- 680 uF ELCO etched
- 2x Mundorf MKP capacitors 2.2 uF / 400 V
- ELCO un-etched 100 uF
- ELCO un-etched 22 uF
- Mundorf MKP capacitor 4.7 uF / 400 V
- Mundorf MKP Supreme 6.8 uF
- Mundorf MKP Supreme 2.2 uF
- Mundorf MKP 22 uF / 400 V
- 4.7 Ohm resistor MOX10 (yellow-purple-gold)
- 3.3 Ohm resistor MOX10 (orange-orange-gold)
- 1.0 Ohm resistor MOX10 (brown-black-gold)
- 10 Ohm resistor MOX10 (brown-black-black)
- 5.6 Ohm resistor MOX10 (green-blue-gold)

Price for Cumulus Horn kit, with high quality crossover, without impedance correction:
without cabinet per unit: EUR 889,00

Cumulus Horn with absolute top high-end crossover

The standard crossover is already equipped with high quality components. Should you want to use only the best components, then the magazine Klang+Ton recommends the following components to ensure best possible sound.

- 1x coincidentally mounted driver, unshielded
- 1x polyester dampig material
- 0.5x foam sealing tape
- 6 x Allen screws 4x16 mm
- 2x terminals
- 4 m Spirit of HighSilver cable, 2x2.5 mm²
- building instruction

- 3x epoxy glass fibre universal PCB
205 x 140 for mounting the following components:

- 1x 0.56 mH Mundorf cfc10 foil coil
- 1x 1.5 mH Mundorf cfc10 foil coil
- 1x 0.47 mH Mundorf cfc10 foil coil
- 1x 0.27 mH Mundorf cfc14 foil coil

- 1x 0.33 mH Mundorf cfc14 foil coil
- 1x 0.022 mH Mundorf cfc14 foil coil
- 1x 2.7 mH Mundorf cfc14 foil coil
- 5x 100 uF ELCO un-etched (in parallel)
- 82 uF ELCO un-etched
- 2x Mundorf MKP capacitor 100 uF / 400 V
- Mundorf MKP capacitor 22 uF / 400 V
- Mundorf MKP capacitor 4.7 uF / 400 V
- Mundorf Supreme silver/gold 6.8 uF
- Mundorf Supreme silver/gold 2.2 uF
- Mundorf MKP Supreme 22 uF
- 4.7 Ohm resistor MOX10 (yellow-purple-gold)
- 3.3 Ohm resistor MOX10 (orange-orange-gold)
- 1.0 Ohm resistor MOX10 (brown-black-gold)
- 10 Ohm resistor MOX10 (brown-black-black)
- 6.8 Ohm resistor MOX10 (blue-grey-black)

Price for Cumulus Horn kit, with high-end crossover, without impedance correction:
without cabinet per unit: EUR 1419,00

Impedance correction

Should you be using a valve amp, then - for impedance correction - the following components need to be mounted on one of the supplied PCB's:
- 1x 4.7 mH Mundorf air core coil 0.7 mm
- 1x 0.33 mH Mundorf air core coil 0.7 mm
- 1x 15 uF MKP capacitor
- 1x 10 uF MKP capacitor
- 6.8 Ohm resistor MOX10 (blue-grey-black)
- 6.8 Ohm resistor MOX10 (blue-grey-black)

We believe that the components for the impedance correction are already of high enough quality. However, if you prefer higher quality components (cfc coils, MCAP Supreme...), they are available upon request. EUR 26,45

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