Audio signal enhancement and amplification system

• US 6,792,120 B1
• Filed: 02/23/2000
• Issued: 09/14/2004
• Est. Priority Date: 02/25/1999
• Status: Expired due to Fees

• Current Assignee: Jonathan M. Szenics
• Original Assignee: Jonathan M. Szenics
• Inventors: Szenics, Jonathan M.
• Primary Examiner(s): Ramakrishnaiah, Melur
• Application Number:
  US09/511,684
• Time in Patent Office: 1,665 Days
• Field of Search: 381/120, 381/61, 381/59, 381/308, 381/91, 381/118, 381/122, 381/96, 381/150, 181/148, 181/199
• US Class Current: 381/120
• CPC Class Codes: G10H 2220/531 made of piezoelectric film
• CPC Class Codes: G10H 3/146 using a membrane, e.g. a drum; Pick-up means for vibrating surfaces, e.g. housing of an instrument
• CPC Class Codes: G10H 3/187 for distorting the signal, e.g. to simulate tube amplifiers changing the tone color by non-linear elements G10H1/16
• CPC Class Codes: H03F 3/28 with tubes only
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407

Abstract

An audio system includes amplifying with distortion via a first amplifier electrical audio signals from a sound source, such as an electric guitar, for example, to obtain a desired tonal quality in the sound produced from a first loudspeaker driver by the amplified electrical audio signals, simultaneous with applying electrical signals from a piezo film transducer attached to the cone of the first loudspeaker to a second amplifier having a flat response over a desired frequency range, and adjustable low and high frequency rolloff, for driving a second loudspeaker to produce desired perceived tonal quality at relatively low sound pressure levels, with the volume of the sound from the first and second loudspeakers being adjusted to match the acoustics of a room in which the audio system is operating.

Claims

1. A system for enhancing the amplification and reproduction of audio signals comprising:

a source of electrical audio signals;

a first amplifier for receiving and amplifying said electrical audio signals;

a first loudspeaker for receiving said amplified electrical audio signals and converting the same into first sound signals, said first loudspeaker including a cone, and a rear cone driving portion including a stationary magnet, and a voice coil connected to said cone;

a piezo film transducer attached to a portion of the cone of said first loudspeaker for producing cone vibration electrical signals corresponding to the waveform of the first sound signals emitted from said cone;

a second amplifier for receiving and amplifying said cone vibration electrical signals; and

a second loudspeaker for receiving and converting said cone vibration electrical signals into second sound signals;

said second amplifier including means for both phase inverting said cone vibration electrical signals, and for selectively controlling the high and low frequency rolloff, respectively, for adjusting the sound output of said system to the acoustical characteristics of a room in which said system is operating in accordance to the preference of a listener, said system operating to permit tone generation to be independent of volume levels;

means for driving said first amplifier and first loudspeaker to a level of distortion for obtaining a desired tonal quality at relatively low ambient sound pressure levels; and

said second amplifier having a flat frequency response over at least a frequency range of signals received from said piezo film transducer.

2. The system of claim 1, further including:

a first loudspeaker cabinet that includes a sealed back portion and an open front portion for permitting sound waves from said first loudspeaker to be emitted therefrom, and acoustic dampening for minimizing standing waves; and

said first loudspeaker being mounted inside said first speaker cabinet in a manner floating the cone thereof.

3. The system of claim 1, wherein said piezo film transducer is radio frequency (rf) shielded, and connected to said second amplifier via an rf coaxial cable.

4. The system of claim 1, wherein said source of electrical audio signals consists of an electric guitar.

5. The system of claim 4, wherein said second amplifier consists of a vacuum tube amplifier for obtaining optimal tonal quality for the sound produced by said system.

6. The system of claim 4, wherein said piezo film transducer is rf shielded, and connected to said second amplifier via an rf coaxial cable.

7. The system of claim 5, wherein said second amplifier includes:

a preamplifier including at least ten megohm input impedance, lower plate voltage than the rated plate voltage of all vacuum tubes therein, the latter having high gain cathodes, a Baxendall-type tonestack with rolloff adjusted to match the combination of said first amplifier and first loudspeaker with said piezo transducer to the combination of said second amplifier and second loudspeaker to obtain a desired sound output; and

an output stage including a long-tailed pair phase splitter circuit for high gain and passage of harmonic distortion.

8. The system of claim 1, wherein said piezo film transducer is rf shielded, and connected to said second amplifier via an rf coaxial cable.

9. In an audio system, a method for amplifying electrical audio signals from a sound source in a manner to obtain desired tonal quality at relatively low sound pressure levels with acceptable volume in the reproduced sound to minimize potential hearing loss to a listener, said method comprising the steps of:

obtaining a source of electrical audio signals;

amplifying with a first audio amplifier said electrical audio signals;

applying an audio output from said first audio amplifier to a first loudspeaker including a cone and cone driving mechanism, for producing first sound signals;

attaching a piezo film transducer to a portion of the cone of said first loudspeaker, for obtaining from said transducer cone vibration electrical signals corresponding to the waveform of said first sound signals;

amplifying via a second audio amplifier said cone vibration electrical signals;

applying an output from said second audio amplifier to a second loudspeaker;

adjusting the high and low frequency rolloff of said second audio amplifier to obtain a desired tonal quality in the sound produced by said first and second loudspeakers; and

adjusting the output level of said first and second audio amplifiers to a desired level matching the acoustics of a room in which said audio system is operating.

10. The method of claim 9, further including the step of overdriving said first audio amplifier and first loudspeaker to obtain a desired tonal effect on the sound outputted from said first and second loudspeakers.

11. The method of claim 9, wherein said second audio amplifier is a vacuum tube amplifier.

12. The method of claim 10, wherein said second audio amplifier is a vacuum tube amplifier.

13. The method of claim 9, further including the steps of:

rf shielding said piezo film transducer; and

connecting an rf coaxial cable between output terminals of said piezo film transducer and input terminals of said second audio amplifier.

14. The method of claim 9, further including the step of making the frequency response of said second audio amplifier flat over a desired audio frequency range between the low and high frequency rolloff of said second audio amplifier.

15. The method of claim 9, further including the step of mounting said first loudspeaker in a speaker enclosure in a manner for floating the cone of said first loudspeaker.

16. The method of claim 15, further including the step of acoustically damping said speaker enclosure for said first loudspeaker.

17. The method of claim 16, further including the step of making said speaker enclosure portless, and otherwise sealed except for an opening to emit soundwaves produced by said first loudspeaker.

18. The method of claim 17, wherein said second audio amplifier is a vacuum tube amplifier having a flat frequency response over a desired audio frequency range.

19. The method of claim 18, further including the step of overdriving said first audio amplifier and first loudspeaker to obtain a desired tonal effect on the sound outputted from said first and second loudspeakers.

20. In an audio system, a method for amplifying electrical audio signals from a sound source in a manner to obtain desired tonal quality at relatively low sound pressure levels with acceptable volume in the reproduced sound to minimize potential hearing loss to a listener, said method comprising the steps of:

obtaining a source of electrical audio signals;

amplifying said electrical audio signals;

applying said amplified electrical audio signals to a first loudspeaker including a cone and cone driving mechanism, for producing first sound signals;

attaching a piezo film transducer to a portion of the cone of said first loudspeaker, for obtaining from said transducer cone vibration electrical signals corresponding to the waveform of said first sound signals;

independently amplifying said cone vibration electrical signals;

applying said amplified cone vibration electrical signals to a second loudspeaker;

adjusting the high and low frequency rolloff of said cone vibration electrical signals to obtain a desired tonal quality in the sound produced by said first and second loudspeakers; and

adjusting the amplification levels of said electrical audio signals and said cone vibration electrical signals to a desired level matching the acoustics of a room in which said audio system us operating.

21. The method of claim 20, further including the step of adjusting the level of amplification of said electrical audio signals to overdrive said first loudspeaker to obtain a desired tonal effect on the sound outputted from said first and second loudspeakers.

22. The method of claim 20, further including the step of making the amplification of said cone vibration electrical signals have a flat frequency response over a desired audio frequency range.

23. The method of claim 20, further including the step of mounting said first loudspeaker in a speaker enclosure in a manner for floating the cone of said first loudspeaker.

24. The method of claim 23, further including the step of acoustically damping said speaker enclosure for said first loudspeaker.

25. The method of claim 24, further including the step of making said speaker enclosure portless, and otherwise sealed except for an opening to emit soundwaves produced by said first loudspeaker.

26. The method of claim 25, further including the step of making the amplification of said cone vibration signals have a flat frequency response over a desired audio frequency range.

27. The method of claim 26, further including the step of adjusting the level of amplification of said electrical audio signals to overdrive said first loudspeaker to obtain a desired tonal effect on the sound outputted from said first and second loudspeakers.

28. A preamplifier for impedance matching and buffering a piezoelectric transducer pickup of a musical instrument for connection to a main amplifier, comprising:

a vacuum tube cathode follower circuit having an input terminal connected to an output terminal of said piezoelectric transducer, and an output terminal for connection to an input of said main amplifier.

29. The buffer preamplifier of claim 28, wherein said cathode follower circuit further includes:

a dual triode amplifier;

an RC impedance match circuit included in a first triode stage thereof; and

a tone stack receiving an output signal from the cathode of a second triode stage thereof.