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Page created 25 feb 2019
We have struggled for years to design a small loudspeaker with excellent sound quality and also powerful bass despite its size. And finally we did it!
The HSQ-50-20E kit includes all electronic / electric parts you need for a stereo pair: Two woofers, two tweeters, two filter PCB:s with screw terminals and overload protecion, two speaker terminals, two bass ports, 10 m cable for internal and external wiring, and of course the drawing, cutting template and building instructions in english.
All you have to buy locally is the box material (16 mm fibreboard) and the surface treatment of your choice.

The size is only 20 (W) x 50 (H) x 30 (D) cm, but it still has an impressive bass response.
The speakers and filters are the same as in other SQ-50 models, so the sound quality is top notch.
Just as good for recording studios as for the living room of music lovers with high standards.
Speaker kit for this design: HSQ-50-20E

Top quality sound (as expected), but what really strikes you is the powerful, deep and clean bass, not expected in a small speaker like this.
Bass intensive music like Grace Jonesī "Hurricane Dub" and Bass Mekanikīs "Bass all day" (both available on Spotify) becomes really powerful. No need to raise the bass volume on your amplifier, and no need for a subwoofer even for the lowest frequencies in that music. You both hear and feel the bass even at only 1 - 2 W / channel.
In our shop we have a computer connected directly to our CM-100-17 power amp driving a pair of these speakers, and so far those who have listened to them have been very impressed.

The bass port on the model in the picture above is on the back so you donīt see it. Then, the box needs about 5 cm air behind it to produce full bass response.
However, if you want to place the speaker in a bookshelf or closer to a wall behind it, just put the bass port on the front, the sound quality and bass response remains the same.
So, the SQ-50-20 can be placed on the floor, in a bookcase, your stereo furniture, a table or on speaker stands. Or... why not close to the ceiling as in this picture -- then they will really get out of the way.

This picture shows how small they really are:

Frequency response 27 - 24 000 Hz according to DIN 45500. (48 - 20 000 Hz -3 dB.)
DIN 45500 is a german (but internationally accepted) Hi-Fi standard that takes into consideration how the human hearing works. Extensive listening tests were made in the 1970īs, and the results showed what deviations from a flat response normal human beings could detect when listening to music:
Allowable deviation within 100 - 4 000 Hz: +/- 4 dB (relative the 1 kHz level).
Further allowable deviation -3 dB/octave below 100 Hz and above 4 kHz, see the thick black lower lines:

Blue frequency response = SQ-50-20.
Green frequency response = A closed box with the same inner volume and the same components.
(The plots are dotted above 100 Hz as they overlap each other.)

So, if you want a pair of real high quality speakers with solid bass in a smaller format, SQ-50-20 is it.
Assembling these speakers yourself can save you a fortune compared to what similar sound quality would cost in a dedicated Hi-Fi shop.

Speaker kit for this design: HSQ-50-20E