brassblaster2

8/7/2019 BrassBlaster2

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Corrected Maestro Bass Brassmaster BB-1After a great deal of detective work by some effects makers and comparisons with original units, ithas been determined that the manufacturer’s schematic for the Maestro Bass Brassmaster modelBB-1 is incorrect in one small way: the pinout for the darlington device (2N5308) is shown backwards.This is shown in the corrected schematic below.

The Bass Brassmaster PCB sold by General Guitar Gadgets properly reflects the schematic except inthree ways. These are:1. The positioning of the Darlington is show according to the original, incorrect schematic diagram. Thi

can be corrected by turning the transistor 180 degrees in the mounting holes.

2. The nomenclature for R22 and R27 was reversed on the schematic noting the part numbers for thePCB. If these are reversed, it is then correct compared to the schematic, and has been proven towork properly.

3. The switching on the filter was simplified to simply put one resistor in parallel with the other. For instance, instead of switching from 47K to 6.8K, the two were simply paralleled. This makes theswitching much simpler, requiring only a 3PST instead of a 3PDT switch. It does change the filter frequency slightly, making the high position about 14% higher in frequency. In practice, this changesthe sound of the effect very little.

However... I have updated the PCB layout.

Updates, layouts copyright R.G. Keen 2009. All rights reserved. No permission for local copies or presentarom web sites other than http://www.geofex.com.



3

4

5

1

15

2

13

14

12 +9

+9+9

+8

+9

+9

+8

+8

+8

+9

R17

10K

4.7K

R9

R11470R

R7

470K

C6

1uF

C41uF

Q2 Q3

C1

C3

C5

C9

C8

C2

C14C13

C12

C15

C10

C11

0.1uF

0.1uF

0.1uF

0.1uF

R1

R4

390R150K2.2MR2

150KR3 12K

12K

10K

10K

10K

Q1

1uF

1uF

1uF

VR1

VR2

VR3

Q4 Q5

Q6

Q6

R5

R12

R13

R15

R14 R18

R19

R6

R10

R8

C7

1.5M

150R

2.2K

2.2K47nF

10nF

47nF

4.7nF 4.7nFT1

R21

R29

R31

R30

R22

R26

R27

R24

R23

R25

R28

R20

R16

220K

220K

82K

150K 1.5M

1K

22K

47K 47K 47K

2.2K

3.3K

6.8K 6.8K

In

Out

2M29 Vd c

1N4002C1625uF

C1710uF

R32820R

D5

D1

D2 D3

D4

A B C D E F G H I

K

J

LMNOPQRSTU

V

W

X

Y

V

W

X

Y




SW3: Brass ½

SW2:Harmonic

HiLo

S SR T T

VR1 VR2 VR3

V

V

W

W

X

X

Y

Y

Black

Red

Battery Clip On left edge of board


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