ScottT_10809431_FMP Poster
1
DESIGN AND CONSTRUCTION OF A CUSTOM GUITAR AMPLIFIER TONE SECTION Tim Scott BSc(Hons) Sound Engineering FMV Frequency Response with change to High Control Level (dBV) -40 -30 -20 -10 0 Frequency (Hz) 20 56 159 448 1262 3557 10024 FMV Frequency Response with change to Mid Control Level (dBV) -40 -30 -20 -10 0 Frequency (Hz) 20 56 159 448 1262 3557 10024 FMV Frequency Response with change to Low Control Level (dBV) -40 -30 -20 -10 0 Frequency (Hz) 20 56 159 448 1262 3557 10024 Max 0 Max 0.25 Max 0.5 Max 0.75 Max1 Min 0 Min 0.25 Min 0.5 Min 0.75 Min 1 Product Frequency Response with change to High Control Level (dB) 0 10 20 30 40 50 60 70 Frequency (Hz) 20 55 149 403 1092 2958 8011 Product Frequency Response with change to Mid Control Level (dB) 0 10 20 30 40 50 60 70 Frequency (Hz) 20 55 149 403 1092 2958 8011 Product Frequency Response with change to Low Control Level (dB) 0 10 20 30 40 50 60 70 Frequency (Hz) 20 55 149 403 1092 2958 8011 Max 0 Max 0.25 Max 0.5 Max 0.75 Max 1 Min 0 Min 0.25 Min 0.5 Min 0.75 Min 1 Introduction Mr Goodes, a heavy metal guitar player, has problems with controlling his amplifier when finding a recording tone; • The amplifier offers little control over the sound • The existing control is unpredictable • Having found a tone, transportation between sessions can move the controls and change the tone • In the studio, the sound in the live room is a poor representation of the recorded tone, making it difficult to find the correct tone As such, he has requested an amplifier that will solve these problems Background • Guitar amplifiers were developed in the ‘30s along with electric guitars so that guitarist can be heard in an ensemble (Fliegler and Eiche 1993) • In ’57, the Fender 5F6 provided bass, mid and treble tone controls (Teagle and Sprung 1995) • The circuit design for this became widely adopted, and known as the Fender/Marshall/Vox (FMV) tone stack (Blencowe 2013) • This is the design used in the client’s amplifier, the Peavey 6505+ (Peavey Electronics Corporation 2009) Method • Simulate and analyse the performance of the Peavey 6505+ tone stack • Investigate surrounding technologies to identify possible alternatives to this design • Use a computer assisted design program to develop an alternative tone stack design, using testing simulations to check functionality • Build this design as a prototype • Run tests on the prototype and compare to the FMV results Objectives • Identify the causes of the problems with the current amplifier • Design an alternative tone stack as a solution to the problems • Build a ‘proof of concept’ prototype of the proposed solution The solution should be; • able to store settings between power cycles • capable of a high level of precision and flexibility with predictable results • controllable from a sonically isolated room Peavey 6505+ Tone Stack (Left) • High tone pot boosts above 2kHz but also attenuates below 1kHz; accentuates effect of the control • Mid tone pot works predictable when other controls are high, but when others are low, it attenuates whole signal, while effectively controlling high frequencies • Lowest mid frequency value can only occur when other controls are high • Low pot behaves generally predictably, though settings of other controls alter the exact parameters • Interaction of controls caused by lack of isolation between sections of the FMV RC filter network Solution Design Design of the proposed solution consists of 3 parallel bands, each with second order high and low pass filters, followed by a gain stage with both non-inverting and inverting capability. This interacts with the dry signal to boost or attenuate the chose bands. Input and output is via a single TRS jack cable. Results (Right) • If the damping factor were to be set at an ideal value, it would allow predictable behaviour with little to no interaction between bands • Usability is low due to backwards-operating controls and are unlabelled • Wide range of settings available for each frequency control as well as large variation between highest and lowest level for each band shows good flexibility • Jack cable allows control separation from amplifier • No ability to store settings between power cycles • Problems with design could be easily solved by further prototyping References BLENCOWE, M., 2013. Designing valve Preamps for guitar and bass, Second edition. Lulu.com FLIEGLER, R. and J.F. EICHE, 1993. Amps!: The other Half of rock ‘n’ roll. Hal Leonard TEAGLE, J. and J. SPRUNG, 1995. Fender amps: The First Fifty years. Hal Leonard
Transcript of ScottT_10809431_FMP Poster
DESIGN AND CONSTRUCTION OF A CUSTOM GUITAR AMPLIFIER TONE SECTION Tim Scott BSc(Hons) Sound Engineering
FMV Frequency Response with change to High Control
Leve
l (dB
V)
-40
-30
-20
-10
0
Frequency (Hz)20 56 159 448 1262 3557 10024
FMV Frequency Response with change to Mid Control
Leve
l (dB
V)
-40
-30
-20
-10
0
Frequency (Hz)20 56 159 448 1262 3557 10024
FMV Frequency Response with change to Low Control
Leve
l (dB
V)
-40
-30
-20
-10
0
Frequency (Hz)20 56 159 448 1262 3557 10024
Max 0 Max 0.25 Max 0.5 Max 0.75 Max1Min 0 Min 0.25 Min 0.5 Min 0.75 Min 1
Product Frequency Response with change to High Control
Leve
l (dB
)
0
10
20
30
40
50
60
70
Frequency (Hz)20 55 149 403 1092 2958 8011
Product Frequency Response with change to Mid Control
Leve
l (dB
)
0
10
20
30
40
50
60
70
Frequency (Hz)20 55 149 403 1092 2958 8011
Product Frequency Response with change to Low Control
Leve
l (dB
)
0
10
20
30
40
50
60
70
Frequency (Hz)20 55 149 403 1092 2958 8011
Max 0 Max 0.25 Max 0.5 Max 0.75 Max 1Min 0 Min 0.25 Min 0.5 Min 0.75 Min 1
IntroductionMr Goodes, a heavy metal guitar player, has problems with controlling his amplifier when finding a recording tone;• The amplifier offers little control over the sound• The existing control is unpredictable• Having found a tone, transportation between sessions can move the
controls and change the tone• In the studio, the sound in the live room is a poor representation of
the recorded tone, making it difficult to find the correct tone As such, he has requested an amplifier that will solve these problems
Background
• Guitar amplifiers were developed in the ‘30s along with electric guitars so that guitarist can be heard in an ensemble (Fliegler and Eiche 1993)
• In ’57, the Fender 5F6 provided bass, mid and treble tone controls (Teagle and Sprung 1995)
• The circuit design for this became widely adopted, and known as the Fender/Marshall/Vox (FMV) tone stack (Blencowe 2013)
• This is the design used in the client’s amplifier, the Peavey 6505+ (Peavey Electronics Corporation 2009)
Method
• Simulate and analyse the performance of the Peavey 6505+ tone stack
• Investigate surrounding technologies to identify possible alternatives to this design
• Use a computer assisted design program to develop an alternative tone stack design, using testing simulations to check functionality
• Build this design as a prototype• Run tests on the prototype and compare to the FMV results
Objectives
• Identify the causes of the problems with the current amplifier• Design an alternative tone stack as a solution to the problems• Build a ‘proof of concept’ prototype of the proposed solution
The solution should be;• able to store settings between power cycles• capable of a high level of precision and flexibility with predictable
results• controllable from a sonically isolated room
Peavey 6505+ Tone Stack (Left)
• High tone pot boosts above 2kHz but also attenuates below 1kHz; accentuates effect of the control
• Mid tone pot works predictable when other controls are high, but when others are low, it attenuates whole signal, while effectively controlling high frequencies
• Lowest mid frequency value can only occur when other controls are high
• Low pot behaves generally predictably, though settings of other controls alter the exact parameters
• Interaction of controls caused by lack of isolation between sections of the FMV RC filter network
Solution DesignDesign of the proposed solution consists of 3 parallel bands, each with second order high and low pass filters, followed by a gain stage with both non-inverting and inverting capability. This interacts with the dry signal to boost or attenuate the chose bands. Input and output is via a single TRS jack cable.
Results (Right)• If the damping factor were to be set at an ideal value, it would allow
predictable behaviour with little to no interaction between bands• Usability is low due to backwards-operating controls and are unlabelled• Wide range of settings available for each frequency control as well as
large variation between highest and lowest level for each band shows good flexibility
• Jack cable allows control separation from amplifier• No ability to store settings between power cycles• Problems with design could be easily solved by further prototyping
ReferencesBLENCOWE, M., 2013. Designing valve Preamps for guitar and bass, Second edition. Lulu.comFLIEGLER, R. and J.F. EICHE, 1993. Amps!: The other Half of rock ‘n’ roll. Hal LeonardTEAGLE, J. and J. SPRUNG, 1995. Fender amps: The First Fifty years. Hal Leonard
