Flipster trouble

[Bernardduur]

OK, I love the OD'ed tone that I get from my flipster, but I guess there is something wrong;
- I can't bias Q4 to 4.5V; the lowest it goes is around 5V;
- The sound is always distorted;
- Adding bass only increases distortion (but I guess this is normal);

I tried a lot of FET's (for example J201, 2N5457 and MPF102) but all give the same sound. I've checked and tripple checked my build, rebuild it with the vero layout (other one was of the schematic) and I get the same result.

Help?

[toneless]

Maybe a schematic would help ...but 5v seems ok to me anyway

[Bernardduur]

OK, schematic here

[MartyMart]

4.5 to 5.5 volts would seem about optimum with most of the ROG fet sims ....
Q4 gate is tied direct to ground, how about trying a 220 ohm to 1k resistor there which
may help ?
I dont see a problem with it sitting at 5v IMO

MM.

[Bernardduur]

Hmmm, my main problem is the distortion I get all the time

The bias problem is just a symptom

I know there is some other sound possible; good samples here (not mine!)

[nosamiam]

I'm a relative newbie, but I've played bass for a while.  I have to wonder...

Could it be that the signal is too hot for your recording setup?  Does the distortion go away if you lower the master volume?  Maybe you mention this on the page with your samples, but my German is pretty poor.  Anyway, good luck!  I'm thinking of building one of these some time in the future and from your samples--even with the distortion-- I think I will like it and it will be highly usable for recording.

[Bernardduur]

Ehm, the samples were not mine........ I want mine to sound like that. I only get the real OD / fuzzy tone. Volume and Master work great, only to lower the distortion

[MartyMart]

Have you tried increasing the input resistor (47k) perhaps 68 to 100k would help
if you have breakup with the 1M still at zero...?
Perhaps playing with the 5k6 from Q1 gate would help too ..
I'm just following the "Fetzer valve" ideas ..

MM.

[Bernardduur]

With the 1M at zero I get nothing at all, then slowly fades in the distortion.

I will try the suggestions.

[MartyMart]

Well I just finished one yesterday and don't have the "constant dirt" problem.
I used a 68k input r and a 1uf input cap ( was getting some "hash" noise without it )  and 4m7 from Q1.

All else is stock apart from a different bass/treble setup, like a custom BMP - 1 knob ( I'm out of 1M pots !! )
All fets are J201 and all biased up to 6 volts ( this is suggested on the flipster notes at ROG )

It's sounding great, clean up to 2/3 gain then some grit comes on.
Not the most HUGE output level, but its fine and is sounding quite good through the condor
with some "desk bass" added in.
I dont suppose you're using a bass with a "battery" in are you ?? 
I've had active basses overload almost all my preamps .... I HATE 'em  !!
With a standard P-Bass it's fine and dandy , can even take some compressor boost to input too

MM

[Bernardduur]

OK, found the trouble; had a short circuit through 3 layers of ductape and my gain pot was broken (at 1/2 of the rotation it mirrord).

Now it works just fine. I tried a lot of replacements but stuck to the J201's; they just sound the warmest with my setup I guess. I raised all voltages to 6.0V for more headroom.... Man, try it with bass and treble full with the gain just a notch up and some volume.... drool!

A big thanks to all people who helped me

and of course to ROG!!!!