Bookshelf BS 1 Subwoofer with Seas Excel Drivers published in Hobby HiFi 5/2008

Bookshelf BS1 aus Hobby HiFi 5/2008
Technical data:
- size (HxWxD): 28 x 40 x 35 cm
- impedance: 6 Ohm
- sensitivity: 82.5 dB
- crossover frequencies: 400, 2200 Hz
- frequency range (-3dB): 48 - 18000 Hz
- speaker type: sealed cabinet with high pass

A compact 3-way loudspeaker? That was realised by Bernd Timmermanns with the Bookshelf BS1, a design with the following Seas Excel drivers:

Since a bass reflex solution providing low bass would have resulted in a large speaker Bernd Timmermanns decided to use a sealed cabinet with a capacitor in series to the W22 EX 001 bass driver, called GHP design (geschlossene Bauweise mit Hochpass; or in English: sealed cabinet with high pass). Further information regarding this design you can find on our theory pages.

The speaker may be placed on a sideboard, shelf or speaker stand.

  ... "The listening test exceeded all our expectations. Above a fat and tight bass that was by no means too voluminous but amazingly low, this Excel trio placed a layer of fascinatingly clear and detailed mids and high frequencies. Demanding vocals were the favourite meal of the Bookshelf BS1. Seldom have we experienced Olga Borodina in Stravinsky's Le Sacre Du Printemps (Berlin Philharmonics, Philips) so realistically and three-dimensional. The entire recording of "Le Sacre" was reproduced with an incredible richness, with extraordinary imaging and ease by these masterful speakers. But the BS1 is by no means just for classical music. Even pop and jazz are sound great. Again we had to trouble the Manger CD: the O-Zone Percussion Group's performance was almost explosive matching even the best speakers around. The extremely wide percussion range sparkled with an exceptional resolution and clarity, with adequate punch but never with harshness. Especially the magnesium dome tweeter at it's first appearance has to be given the attribute 'world-class', at least when the bandpass filter is combating the resonance."

Our kit contains per speaker

- 1 Excel T29 MF001 tweeter
- 1 Excel W12 CY 001 bass / midrange driver
- 1 Excel W22 EX 001 bass driver
- 2 binding posts
- 0.5 Damping 10, 970 x 470 mm, adhesive
- 2 Damping fleece MT Bondum 800
- 1/4 bag polyester fleece
- self-adhesive sealing tape
- 18 PAN screws 4 x 20 mm
- 3m speaker cable 2x2.5 mm2, transparent
- building instruction

- 0.7 mm air core coil, 0.10 mH/0.27 Ohm
- 0.7 mm air core coil, 0.033 mH
- 1.0 mm air core coil, 2.2 mH/0.89 Ohm
- Mundorf baked varnish air core coil BL100, 0.33 mH/0.26 Ohm
- Mundorf baked varnish air core coil BL100, 1.0 mH/0.49 Ohm
- Mundorf bs140 core coil 5.6mH/0.26Ohm
- Intertechnik core coil 15 mH, 4.4 Ohm
- 82 uF ELCO, non-etched
- 470 uF ELCO, etched (100Vdc)
- 560 uF ELCO, etched (100Vdc)
- ClarityCap SA capacitor 4.7 uF / 630 Vdc
- ClarityCap SA capacitor 10 uF / 630 Vdc

- ClarityCap PWA capacitor 2.2 uF / 160 Vdc
- ClarityCap PWA capacitor 15 uF / 160 Vdc
- ClarityCap PWA capacitor 47 uF / 160 Vdc
- ClarityCap PWA capacitor 1.0 uF / 400 Vdc
- 10 Ohm MOX10 (brown-black-black)
- 3.3 Ohm MOX10 (orange-orange-gold)
- 2.2 Ohm MOX5 (red-red-gold)
- 4.7 Ohm MOX10 (yellow-purple-gold)
- 6.8 Ohm MOX10 (blue-grey-gold)

Please note: the 0.033 mH coil is already finished, since unwinding of a 0.1 mH coil, as described in Hobby HiFi, might lead to wrong inductance values during production.

Price of Bookshelf BS1 kit, per speaker, without cabinet: on request

High-end version as in Hobby HiFi

Based on the recommendations by Hobby HiFi we suggest the following crossover components:

- ClarityCap ESA capacitor 4.7 uF / 630 Vdc
- ClarityCap ESA capacitor 10 uF / 630 Vdc
- ClarityCap PWA capacitor 2.2 uF / 160 Vdc
- ClarityCap PWA capacitor 15 uF / 160 Vdc
- ClarityCap PWA capacitor 47 uF / 160 Vdc
- ClarityCap PWA capacitor 82 uF / 160 Vdc
- ClarityCap PWA capacitor 1.0 uF / 400 Vdc
- Mundorf, electrolytic capacitor, etched, 470 uF/63 Vdc
- Mundorf, electrolytic capacitor, etched, 560 uF/63 Vdc

- 0.7 mm air core coil, 0.10 mH/0.27 Ohm
- 0.7 mm air core coil, 0.033 mH
- 1.0 mm air core coil, 2.2 mH/0.89 Ohm
- Mundorf copper foil coil CFC14-0.33mH/0.13Ohm
- Mundorf Hepta Coil II60, 1.0 mH/0.27 Ohm
- Mundorf bs140 core coil 5.6mH/0.26Ohm
- Intertechnik ferrite core coil 15mH/4.4 Ohm
- 10 Ohm MOX10 (brown-black-black)
- 3.3 Ohm MOX10 (orange-orange-gold)
- 2.2 Ohm MOX5 (red-red-gold)
- 4.7 Ohm MOX10 (yellow-purple-gold)
- 6.8 Ohm MOX10 (blue-grey-gold)

Please note: the 0.033 mH coil is already finished, since unwinding might lead to wrong inductance values during production.

Price for Bookshelf BS1 kit without cabinet: on request

Our recommendation for a top crossover

In addition to the high-end version by Hobby HiFi some further improvements are possible: the coil in series to the bass driver should be a large copper foil coil instead of ferrum- or i-core, both would result in harmonic distortion. Also in series to the bass driver, the lossy 560 uF capacitor should be replaced with two 470 uF and 82 uF capacitors in parallel. This combination shows a considerably lower loss. All coils in the driver network are at least baked varnish; in series to the tweeter we recommend Mundorf MCAP supreme capacitors. All foil capacitors are Mundorf Audiophile MCAP with 400 VDC:

- 5.6 mH copper foil coil with 0.34 Ohm
- 15 mH powder core coil 4.4 Ohm
- 1 mH Tritec coil 7x0.5 mm baked varnished wire
- 0.1 mH baked varnish air core coil, 0.7 mm
- 2.2 mH baked varnish air core coil, 1 mm
- 0.33 mH copper foil coil, 2.1 mm2
- 0.033 mH baked varnish air core coil, 0.7 mm
- 0.27 mH copper foil coil, 2.1 mm2
- 82 uF Mundorf MCAP foil capacitor.
- 470 uF ELCO, etched (100Vdc)
- 560 uF (470 uF etched in parallel to 82 uF MKP)
- 47 uF Mundorf MCAP foil capacitor

- 2.2 uF Mundorf MCAP foil capacitor
- 15 uF Mundorf MCAP foil capacitor.
- 4.7 uF Mundorf MCAP Supreme
- 10 uF Mundorf MCAP Supreme
- 1.0 uF Mundorf MCAP foil capacitor
- 22 uF Mundorf MCAP foil capacitor
- 5.6 Ohm MOX10 (with coil 10-11 Ohm)
- 3.3 Ohm MOX10 (orange-orange-gold)
- 2.2 Ohm MOX5 (red-red-gold)
- 4.7 Ohm MOX10 (yellow-purple-gold)
- 6.8 Ohm MOX10 (blue-grey-gold)
- 12 Ohm / 20 Watt ceramic resistor

Please note: the 0.033 mH coil is already finished, since unwinding might lead to wrong inductance values during production.

Price for Bookshelf BS1 kit without cabinet with top crossover: on request

Impedance correction

When using a valve amp an impedance correction is needed. The correction is the same for the standard and ultra version since the component quality hardly influences the sound quality. The impedance correction consists of:
- 0,22 mH air core coil / 0.7 mm
- 47 uF ELCO non etched
- 4.7 uF MKP capacitor

- ClarityCap PWA capacitor 22 uF / 160 Vdc
- Mundorf air core coil L100, 0.27 mH/0.23 Ohm
- ceramic resistor 12 Ohm/20 Watt

Price Bookshelf BS1 impedance correction pro unit: EUR 13,96 excl. VAT: € 11.73 / $ 13.26

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