TS 9 circuit

Effects

From bew456--(at)--eus.tamu.edu Mon May 16 20:43:04 CDT 1994
From: bew456--(at)--eus.tamu.edu (Bruce E.)
Newsgroups: rec.music.makers.guitar
Subject: Simple Distortion Circuit v0.2
Date: 16 May 1994 14:29 CDT
Distribution: world
News-Software: OpenVMS/VAX VNEWS 1.41

From: bernard--(at)--cnsun.ECN.NL (Marcel Bernards)
Subject: Re: Schemata - speaker load boxes, Fuzz; re: tube screamer posts
Date: 29 Apr 1994 09:18:19 +0200


I have the service manual of the original TS-9, it's nothing special really..
just a 4558 OpAmp with two antiparallel MA150 Diodes and a small tone circuit.
and a input and output transistor buffer (emittor followers)

It's too complex for making an ASCII drawing :-)

I am surprised that this thing is causing such a hype on r.m.m.g.
It is really a very common schematic of a signal clipper published in
several electronic magazines etc. I have made such circuits many times, and
I could not hear very much difference between them and an original TS9.

Cheers,

--
Marcel Bernards, UNIX & Net sysadm ECN - Netherlands Energy Research Foundation
Facilities Dept. - Group Computer & Network Management: E-Mail: Bernard--(at)--CN.NL
SnailMail: P.O. Box 1, 1755 ZG Petten Phone: (+31 /0)2246 4579 Fax: (+31 /0)2246 1864
SCREAMNet : AAAAAARGHH!HUH?? : Disclaimer: "The AntiChrist is the Computer !"





Here's the new, improved file. The circuit is correct. I've included some of
the voltages and currents you should be seeing. The only difference I've seen
between the parts list and mine is the value of Cc (which I've changed to 1.0
mfd to give better bass response with low-impeadance amps) and the use of
Radio Shack's MPS3904 transistor rather than my National 2N3904. The
transistor difference shouldn't matter, though. They both have the same
specs.

Here is a little distortion circuit that I kinda like. It's very easy to
build and sounds amazingly like an Ibanez TubeScreamer. With the exception
of the diodes it is the circuit for the Electra Power Overdrive module (the
one that went inside the guitar--another relic of the '70's). It's important
to use Germanium diodes to get the right sound. The voltage out is .4 volts.
If you need more power and less distortion use Silicon diodes, for 1.4 volts
output (to get more distortion use the mod listed below, use Ra = 100 and
Ca = 8 mfd for a gain of 45). By the way, this is a common-emitter amplifier.

For those of you needing an exact duplicate of the TubeScreamer, you'll need
to add 2 more parts, indicated as Ra and Ca. These are added to lower the
A.C. gain below the cutoff frequency (f = 1/(2*pi*Ca*Ra)) to duplicate the
TubeScreamer bass roll-off. Ra should be 270 to 330 ohm, and Ca
selected to give the proper cutoff frequency, I guess around 200 Hz. I'll try
to find it exactly. I haven't tried this mod. Good luck.

Vcc=9v
|
|
/
\
/ Rc=4.7K
\
/
Rb=2.3M | (Xout=5K)
/\/\/\/\-o | |
| o-------| |--------o-------o---> Out
| | | | | |
| /C | |
(Xin=50K) | | / Cc=1.0 mfd -----D1 -----
| | | |/ /^\ \./ Both Ge-type
In >-----| |------o----| 2N3904 ----- D2-----
| | B |\ (NPN:gen. purps, | |
| \ small signl.) | |
Cb=0.1 mfd \E |---o---|
\| |
| |
o---------. -----
R S # | | ---
Q: 2N3904 276-2016 / \ -
D1,D2: 1N34A 276-1123 \ / Ra
Cb: 0.1 mfd 272-1069 / \
Cc: 1.0 mfd 272-1434 \ Re=470 / Vb = 0.8 - 0.9V
Re: 470 271-019 / | Vc = 7.0V
Rc: 4.7K 271-030 \ ----- Ve = 0.1 - 0.2V
Rb: 2.2M 271-061 | ----- Ca Ic = 0.5mA
9V jack 270-325 | |
Perfboard 276-149? ----- -----
Box 270-235? --- ---
Jacks(2) 274-252? - -
Switch 275-011?

Now for all you electronics types who just said, "Heck, that just hard-clips
the signal. It'll sound horrible", you should realize that the gain of the
transistor is changing with the signal level, and has the effect of rounding
out the upper lobes of the undistorted wave. If you don't believe me just put
it in your PCSPICE program and watch what it does. I don't claim credit for
the circuit--the Electra people came up with the amp, and I was just fiddling
with it and found that this worked well--later on I figured out why. If you
want an uninverted signal (if you think there is a difference) take the signal
off the emitter instead of the collector. It might not sound the same,
however. I didn't test it. Connect the left-hand side of Cc to the emitter
to do this.

I've noted that the Screamer mixes some of the original signal in with the
distorted signal, and the mix seems constant mo matter how distored the signal
gets--the setting of the distortion knob effects only the distorted signal
drive. This may be wrong, but that's what it sounds like to me. If you want
to do this, you'll need to take the signal off the collector, otherwise you'll
get some wicked bass phase cancellation when you mix the signal with the
original.

Have fun with it. Should cost about $20 from Radio Shack components,
including jacks, box and a footswitch.

Ask me about it if you need to.

Bruce
bew456--(at)--eus.tamu.edu

Index:

Chandler Tube Driver Tubes	Ibanez 8 Series Effects	JRC4558 specs	Klemt Echolette
midiverb ii	No Salvage JRC4558Ds	TS 10 differences	TS 5 feedback changes
TS 5 to TS 9	TS 9 4558 Op Amp	TS 9 circuit	TS 9 Fix Switch
TS 9 opamps	TS 9 operation	TS 9 switch	TS 9 to TS 808
TS 9 vs TS 10	TS 9 vs TS 808