I just finished building the "Rocket" but I think mine's a Scud!

[Burstbucker]

I finished up the Rocket Fuzz but I'm not at all happy with it.
8^(

It doesn't sound at all like the description states, "smooth, great sustain and rich fuzz", "I like this pedal more than my Big Muff and Colorsound Tonebender".  I must have screwed something up!?

My pedal has pretty smooth-sounding distortion alright but it's God-awful bright!  It sounds like I've got a Treble Booster hooked up, I'm not sure if this is typical or not.  Something else too, it's really shy in the volume dept.  When the Volume knob is cranked, it's not even at unity gain with the bypassed signal.  Maybe a 100K or 500K volume pot would be better then the stock 10K pot?  It would be louder and maybe not let as much highs through, right?

I remember reading a few comments from different guys saying that they had problems with oscillation and gave up on this pedal.  Mine was squealing quite a bit too but I tamed it down some by increasing the 100 ohm resistor on Q2's emitter to a 180 ohm, now it's working a bit better.  But I've got to rectify this problem with the excessive shrillness of this pedal and get the pedal to let through more low end, and also increase the volume.

Can somebody give me hints as to what might rectify these problems and if you've had these problems with the Rocket too?  Thanks!

[RDV]

The Rocket has a tone pot for this purpose. You didn't mention yours. What schem are you using?

RDV

[Burstbucker]

http://www.diystompboxes.com/pedals/rocket.JPG

Yeah, I've got the 10K Tone pot hooked at the junction of those two series caps on the output, this pot is connected to a .1uF cap to ground.  It works okay but just when I'm getting to the point that the treble is halfway tolerable  the volume is much too low.

Something else that might be causing this extreme brightness and lack of low-end might be that the Drive knob is connected to Q1's emiter rather than its collector?  When connected to Q1's emiter, isn't it acting as a buffer and making things way brighter?  Excuse my lack of knowledge, I could be way off here.

[RDV]

http://www.diystompboxes.com/pedals/rocket.JPG

Yeah, I've got the 10K Tone pot hooked at the junction of those two series caps on the output, this pot is connected to a .1uF cap to ground.  It works okay but just when I'm getting to the point that the treble is halfway tolerable  the volume is much too low.

Something else that might be causing this extreme brightness and lack of low-end might be that the Drive knob is connected to Q1's emiter rather than its collector?  When connected to Q1's emiter, isn't it acting as a buffer and making things way brighter?  Excuse my lack of knowledge, I could be way off here.

I got rid of all the .01µF caps and used .1 in their place. I also used a 100k volume pot. I also believe I added another .1 in parallel with the one in the tone contol.

HTH

RDV

[lerxstlover]

Take a look at the scheme on R.G.'s website www.geofex.com: 

http://www.geofex.com/PCB_layouts/Layouts/rocket.pdf

I just finished this one up (with some help!) and I L-O-V-E it.  It's a bit different from the scheme you posted.  I socketed the caps as suggested for tuning and was able to take out some of the highs.  With the tone turned almost all the way up it produces a really warm sustained distortion and brighter/crunchier as you turn the tone down.

I had the same problem with volume when I finished it, so I built the audio probe tool on geofex.com and was able to trace the signal all the way to the last cap before the volume pot.  After that cap the volume got really low, so I replaced the cap and it worked perfect.  I REALLY recommend building the audio probe if you have not already done so.  It is extremely easy to build and makes debugging SO much easier!

http://www.geofex.com/FX_images/audioprb.gif

Good luck!

[petemoore]

  Seems like it shouldn't be too *shrill, and I'd guess it would still have greater than unity output with the tone knob turned down.
  It has a cap across the 1k [top resistor] which tones down high end.
  Are the bias readings in line with the bias of the circuit?
  There are other ways to tame high end using small caps, perhaps across Q2's B/C connections or between input SP and ground.

[Burstbucker]

Thanks so much fellahs for taking the time to give me suggestions. 

RDV,
I ended up using a 0.15uF in the Tone control because that's all I had on hand.

lerxstlover,
What value did you settle on for that cap that you replaced?  I'll check out that audio probe, thank you!

petemoore,
The pedal might be at unity gain(just barely) when the Tone knob is set for maximum treble and the Volume knob cranked but then it's way too bright.  As far as bias readings, I don't have any info on this.  I can tell you that I'm getting about 5.5V between the Collector of Q3 and ground.

[lerxstlover]

lerxstlover,
What value did you settle on for that cap that you replaced?  I'll check out that audio probe, thank you!

The bad cap I replaced was a 0.1uF, but I changed C2 (on R.G.'s layout) to a .1uF.  Hope that helps!

[mac]

Try using some moderate gain Ge instead of Si. It will sound a lot better IMO.
http://www.activeboard.com/forum.spark?forumID=43044&p=3&topicID=4161014



mac

[aron]

Something doesn't sound correct. You shouldn't have to change the transistors to Ge. I wish I still had the Rocket sample lying around.

[petemoore]

  Should be a high gain pre-buffered FF sound.
  With the tone control shaving off s'ome highs...
  That'd be high output with controls set high, [er...IIRC, when functioning right] much above unity.

[Gus]

The first stage is an emitter follower.  It is setup for input load that I like for buffered fuzz/ distortion  The emitter should be at about 5.  something depending on the battery voltage. 

What type of amp are you using?
   What size speaker?
     Have you used say a BMP or another fuzz distortion  with the same amp and guitar?

I am guessing Aron might have built this for use on stage.  Stage vol design is often tuned different.  Some effects need a 20 or more watt tube amp 12" speaker(s)  turned up to get the "sound": However the .1uf and 1.2K output high end rolloff should take away a lot of highs.

  I have not built the rocket but have built the 3 tran no one I know think it sounds shrill.  The 3 tran has a .01uf  and 1K thats a higher turn over than the rockets output stage.

Are the caps the right values?

 

[RDV]

My Rocket Sample

RDV

[aron]

Yeah but RDV you make everything sound good 

[RDV]

Yeah but RDV you make everything sound good 

Thanks Boss!
I don't post the ones that don't sound good.
Usually.

RDV

[Burstbucker]

I was having a bad day yesterday, overtired and having little patience.  Tonight I was feeling re-energized and had another go at this pedal, now that I've tweaked it a little bit, I can say that this Rocket Fuzz truly rocks!!!   I take back everything negative that I had to say about the Rocket yesterday.
8^)

I've got to admit that I didn't take that advice about socketing the caps, doh!!!  Tonight I replaced the stock 0.01uF cap in C3 with a 0.1uF cap.  And even more importantly, I tried different values for C2, I settled on a 0.027uF, this is a little more than double the stock value.  I also have a 180 ohm resistor on Q2's emitter, rather than the stock 100 ohm.  I have a 0.15uF cap in the Tone control.  I also replaced the stock 10K Volume pot with a 100K, the volume is pretty decent now.

As far as voltages go, I've got....................
5.1V on Q1's emitter
1.43V on Q2's collector
5.15V on Q3's collector
I'm not sure if these voltages are okay or not.

I also put a 47uF cap between negative ground and the +9V rail.  Pedal seems pretty quiet now. 

With these changes, I've got a super fat sounding fuzz and yes it's very smooth just like everybody said.   

What's funny is that when I tried a 0.1uF cap in C2, it reminded me a lot of the Catalinbread SuperChargedOverdrive pedal that I used to own, I'm in no way implying that the guy at Catalinbread used this circuit but I'm just saying that there was quite a similarity in the sound, very cool. 

FWIW, I find that the way I have my pedal set up right now with that 0.027uF cap in C2, it could be called "Brian May-in-a-can"!  I find it sounds a LOT like a cranked VOX AC30, really smooth.  That's just my opinion, YMMV.

BTW, I've got a Twin Reverb with WeberVST California 12" speakers, a 1970 Traynor YBA-1 BassMaster 50W head and 4x12 closed back cab with Celestion Greenbacks, and also a Peavey Classic 50/410 with four Celestion speakers in there.

Sorry for not trying out more caps before posting here, it makes a world of difference, I should have known better, oh well..........................

Thanks again for all your input guys, it's always informative here.  And RDV, nice job on your pedal!  Mine sounds similar but with a bit more of a VOX AC30 slant IMHO.

[aron]

Cool. I was thinking of building another one again. My original had too many sockets.

[Burstbucker]

Tonight I decided to get rid of the Tone control all together and put a 100K pot in its place to be used as a blend knob for the input cap.  I went and put back in the stock 0.01uF input cap and used this new "tone" knob to blend in a 0.1uF in parallel with it.

This is perfect for my needs as I've got a couple guitars with single coils and a few with humbuckers, I've done this on the many Fuzzfaces that I've built in the past and I really find that it helps to make the pedals more functional.

When I first built the Rocket, I found it really shrill with the 0.01uF input cap but I guess that it wasn't so much a problem of it being overly bright but it was just lacking way too much bottom end IMHO, now that I'm able to fine tune the input cap everything is wonderful and marvelous!
8^)

[lerxstlover]

This is perfect for my needs as I've got a couple guitars with single coils and a few with humbuckers, I've done this on the many Fuzzfaces that I've built in the past and I really find that it helps to make the pedals more functional.

I solved that problem a while back....I took my Fender Strat (most favoritest of axes) and put a hot rails in the bridge position with a coil splitter switch.  Now I have single-coil, humbucker in series or parallel back there.  That way I get to play my favoritest of guitars and get different tones as I need them.  I know it's not the same thing as playing a Les Paul or whatever, but I just got tired of switching guitars...

That sounds like a cool mod.  I may try that!

[lovric]

to the top of the thread Q: of turning treble down causes the volume to go down as well. m_hammer proposed simply wonderful tone control somewhere on the forum.

he said the treble pot is mounted in line with the signal and the cap is attached to the wiper so the volume stays as you change the treble. although, inline resistance would lower the signal.