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Parallel port sound card with high quality tuning options, compatible with Covox Speech Thing.

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in stock

€ 23,00
€ 22,00
Price per unit

Stock :


New 2020 batch of CVX4 is now available !

Have a look at my other MIDI/sound products as well, for combined shipping.


Parallel port soundcard with high quality tuning options, compatible with Covox Speech Thing
Line out connection, intended to connect to amplified speakers

No compromises, we wanted to make the best possible covox clone, and did not spare effort or expenses :
after building 3 prototype generations (CVX1, CVX2, CVX3), this is now the final version :

CVX4 uses very high precision 0.1% all same value resistors, and a reverse engineered schematic (based on a real original covox) for excellent 8 bit sound. Other DIY clones use 1% or 5% resistors, different schematic, ...you can compare... CVX4 sounds way better...

Added low pass tuning options to simulate speaker effect to your own taste.

Dip switch legend :
dips 1-5 : low pass filter

1: 1nF      : significant low pass filter
2: 4.7nF   : heavier low pass filter
3: 10 nF   : very heavy low pass filter
4 : 0.1nF  : very subtle low pass filter
5 : 0.47nF : subtle low pass filter
dip 6-7 : extra volume divider :
6 :    56k    (1/2R) : 
7 :    27k    (1/4R)
dip 8 
8 :    bypass coupling capacitor
Dip settings for authentic Covox' sound : dip 7 on, other dips off.

Example DIP switch settings :
DIP SWITCH Position :
Result :
E-D-D-D-D-X-X-X low pass filter set medium
D-E-D-D-D-X-X-X low pass filter set heavy
D-D-E-D-D-X-X-X low pass filter set very heavy
D-D-D-E-D-X-X-X low pass filter set very low
D-D-D-D-E-X-X-X low pass filter set low
X-X-X-X-X-E-D-X extra volume divider set half
X-X-X-X-X-D-E-X extra volume divider set a quarter
X-X-X-X-X-X-X-E bypass decoupling capacitor
Legend:    E = (e)nabled or on; D = (d)isabled or off; X = doesn't matter

Review and detailed development history by Scali here : https://scalibq.wordpress.com/2017/11/28/the-covox-years/

CVX4 soundcloud demos here : https://soundcloud.com/user-919839499/sets/cvx4-mod-playback-with

CVX4 playing a song using CVXPlay in DOS :

Fasttracker II through CVX4

CVX4 in games : Electro Man 

Review/Demo by Phil's computerlab:

Featured in this 8 bit guy demo :

CVX4 Modmaster Demo by FreddyV Retro Zone