TS-9 mod for open sound

[brrt]

Hi, I modded a TS-9 so that it has a some more gain. Sounds nice when I need some true evil sound  :twisted:
I'm almost satisfied, but it tends to sound muddy. I can't  "hear" my strings. I want it to sound more open.
My problem: I can define the problem in these "sound" terms, but can't convert them into electrical terms (lower this cap, change that resistor etc.)... Anyone can?

TIA
Brrt

[petemoore]

Uh you could add seriesed Diodes to the diodes in the feedback loop.
 if they used to look like this:
 <
 >
 You can add parallel ones so the configuration looks like one of these
 >>
 <<
 -----------------------------------------------------
 >>>
 <<<
 for assymetry either or
 >>
 <
-------------------------------------
 >>>
 <<
 Of course the cap value going across the diodes could be altered while your'e in there...I like to bring the cap value up just till the hiss is tolerable or goes away.
 More or less bass content can be had by upping or lowering cap values in the circuit signal path...I would look at mods pages for those.
 No....I'd socket the feedback loop, try the diode tricks.
 I've built 'test' boards before with sockets all over the place on it, for certain circuits... /... breadboard it.
 I assume you've heard all the opamp swap talk..try a 4558 or 5532,

[R.G.]

Read "The Technology of the Tube Screamer" at GEO for what affects what.

[dev]

What gain mod did you do?  A larger gain pot?  Or did you put in a larger cap and a smaller resistor series to ground?  To get your highs back you can reduce the value of the 4.7 k resistor (try a trim pot) to ground that is coupled by a 0.047uf cap to pin 2. or you could lower the value of the    51 pf cap between pin 1 & 2.  Playing with the clipping diodes can clean up the grit if you want that.

Dev

[swt]

I think that the best way to open the sound is: change the electrolitics (1uf) for metal type. Change the tantalum for metal ones. Increase the 510k resitor at first buffer to something around 680k. And if none of these is still enough, lower the 1k resistor at the output of ic1. Let me know if it works for you...

[brrt]

I did the "normal" TS-9 to TS-808 (using the RC4558P), changed the input resistor to 620 kOhm, changed all caps to metalfilm. I changed one of the diodes to a 1N4001 and changed the values of the 4.7k resistor and 0.047uF cap. Also I changed the resistor in serie with the drivepot so the gainrange got shifted.
I didn't try to change the cap in the feedback loop. What's his function? Is it to prevent the opamp to oscillate?

grt, Brrt

p.s. I read the technology of... Over and over again.. And I liked it  

[brett]

changed the input resistor to 620 kOhm

The input resistor is usually 1k.  Or do you mean the bias resistor on Q1 (usually 510k?).

In any case, increasing either the input resistor or the input cap will lower the frequency threshold for the bass that passes through.  Low frequency bass is a problem for this circuit, as you've found.

cheers

[brrt]

so:
muddy -> more low than high frequency
open/defined -> more high than low frequency

is this correct?

Brrt

[javacody]

I've done exactly the mod you are talking about. You want more diodes. I ended up with 5, 3 on one side and 2 on the other. It really opens up the sound a lot while sweetening it up at the same time. I used all 914 type diodes.