Ampeg - Sub Blaster  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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modman
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Post by modman »

What an incredible thread to look at: spanning almost 4 years, through 3 or 4 personal trace attempts, in order to be sidetracked by a factory schematic with mistakes, to still come home.
:applause:
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chicago_mike
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Post by chicago_mike »

This thread is almost 4 years old???? Crap, what the hell have I done with my life!!!!! :slap:
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amapolasola
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Post by amapolasola »

Hi there,

i changed all caps in my original sub blaster ; when originals caps were soldered i saw for C10 ...KAN 423
C16 ...KFE 449
C13 ...KAN 503
C5 ....KBL 317
C8 .......KFE 449
...
...

...but it meant nothing ! So when i desoldered caps i saw for c10 ...332 ...it's 3.3nf
c16 and c8....104...it's 100nf
c13 ...473.....it's 47nf
c5...224 ...it's 220nf
c6...153...it's 15nf

so, in the case where caps are coded...(yes that exist) you have to take capacimeter !

i wanted to change opamp tl062 too. I tried and tested opa2134, LM4562, OP275, NE5532...but in this circuit nothing o fthese opamp was better than tl062 ! You have of course a signal, it's very special to define this signal. I built a divided octave too ; and opa2134 work very good with this unit !

I dont have mods for sub blaster, but someone have any mods ...yyuuuuuuuuuuuuu "welcome"


greetings

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chicago_mike
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Post by chicago_mike »

You can put a variable filter in the tone control section, like EBS Octabass or the Aguilar Octamizer. :)
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roseblood11
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Post by roseblood11 »

Is there a complete schematic (and maybe a layout) for the Aguilar Octamizer?

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chicago_mike
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Post by chicago_mike »

Aguilar epoxies the circuits. And the service manuals don't show the epoxied parts.
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rocket8810
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Post by rocket8810 »

i've got the aguilar octamizer and would be happy to help figure out what's under the epoxy. any idea how to get it off?

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bmxguitarsbmx
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Post by bmxguitarsbmx »

Looks like a boss oc-2 with only one octave. The level dependant comparator circuit is the interesting part imo.

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Post by rocket8810 »

i worked through the parts of the aguilar octamizer PCB that's traceable, ie not under the black epoxy, and it's definitely based on the sublaster.

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analoguist21
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Post by analoguist21 »

Trippy Demon wrote:Alright, finished building and debugging, the 1N4002 also needs to be turned around on the pcb, so here's the verified pcb layout
[ Image ]
Trippy Demon wrote:Was also a mistake in the schematic, but this is the definitive one
[ Image ]
Hello everybody,
first of all a big THANKS to all the guys who work on that, the topic is wonderful !
I'm about to build it, is there any little mistake on the last PCB and schematic ? it seems all right !
Can't find the BOM, i will do and post it !
Last question:
I wonder if i can add FX loop on the Dry signal, just before the direct pot, with a ringer, like the mutron octave divider :hmmm: ?
am I wrong ?

Regards !

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analoguist21
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Post by analoguist21 »

http://docdro.id/oLJBmb7

Here's a little document with the B.O.M and labels.
I'm ordering that now, I will post some photos of my work !

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shaggy45
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Post by shaggy45 »

Anyone one build a working one of these from the above layout and have voltages they could share? mines a thud machine

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shaggy45
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Post by shaggy45 »

I tried audio probing the circuit and the noise starts right at the beginning of the circuit. starts at the 2k2 470k connection.
I went over the board and verified the resistors, caps and orientation, diodes and orientation, ics and orientation and transistors.
i went through and knifed in between pads to make sure of no bridges.I started taking out ICs the noise goes away when i remove either u1 or u4.
I've gone over the schematic along side the layout and i don't see any errors.

Heres my voltages:

u1
--
p1 3.44-3.56
p2 3.78-3.84
p3 3.88-4
p4 0
p5 3.37
p6 3.41
p7 3.43
p8 8.20


u2
--
p1 2.9-3.1
p2 0
p3 4.6-5
p4 0
p5 0
p6 0
p7 0
p8 2.68
p9 0
p10 3.75
p11 0
p12 3.75-3.85
p13 4.8-5.0
p14 8.16

u4
--
p1 3.90
p2 3.86
p3 3.84-3.90
p4 0
p5 4.25
p6 3.87
p7 3.88-4
p8 8.20

u5
--
p1 2.66
p2 4.1-4.7
p3 3.97
p4 0
p5 3.78-4
p6 3.9
p7 3.6-3.9
p8 8.20

u6
--
p1 3.75
p2 3.89
p3 3.3-3.5
p4 0
p5 3.88
p6 3.6-4
p7 4.2
p8 8.20

j175
------
d 3.8-4
g 3.6-3.7
s 3.8-4

2n5088
---------
e 3.2
b 3.9
c 8.15

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chicago_mike
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Post by chicago_mike »

Double check the schematic and layout with the original amp, there's a chance of a missing trace off the CD4013, I think off pin 7 or something...??? I forget.
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shaggy45
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Post by shaggy45 »

it all seems to be there mike. i don't know. i even put my board under a digital microscope to look for solder bridges etc and nothing. i think ill re-etch another board with thicker copper and try again. i'll use adapters for the diodes and transistors this time.

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chicago_mike
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Post by chicago_mike »

Post a piccie of your pub trace side.

Just on the off chance there is a trace missing. Its coming off the CD4013. I had to do an edit on one of my etches.
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