Piggyback Treble Booster

[will]

Hi Brian,

I put in a new Q1 transistor a 2N5089 and connected the collector to a .022uf mylar connected to a switch to 9v and disconnected the .01uf I had bypassing the top 1/2 of the collector resistor for Q2. This is to simulate your configuration. It sounded quite good. It's a similar treble roll off as the .01uf I had connected.  I'm not sure what emitter-to-emitter resistor you are using. I'm currently using a 1.5K resistor. The gain is always maxed out to get the harmonic distortion on the peaks. Sounds really good as a very mildly distorted signal into the clean amp, if the volume is maxed on my guitar and I pick the strings hard.  It also sounds great into my very modified Distortion + clone.

I reconnected the .01uf and have your .022uf on the switch to smooth out the highs even more. This does reduce the distortion quite a bit. I also have the 120pf mica cap on Q2 base to collector on a switch. I like it best on. It seems to cut the very high freq with out reducing the distortion. I think I will just solder it in permanently.

So how does your circuit compare to the Rangemaster now? I would be interested in all the areas it differs.

Regards,
Will

[brian wenz]

Hello Will--
   My emitter to emitter res. is 10K.   Oh, did you put a .0068 input cap in your circuit??
As it sits now, the pedal sounds very rich and full with real "beefy" mids and more low end then my germ. version.  The drive control is VERY useful.....it sounds closer to a stock germ Rangemaster when the drive is set on about  75%.
Did you see my newer post on "tweaks" ??  I mentioned that I test everything through tube amps......I remembered that I didn't tell you that before.
I wonder what yours would sound like with the 10K emitter res.??
Brian.

[will]

Hi Brian,

I changed the emitter-to-emitter resistor back to 10K and upped my input cap to .0068 uF. It sounds great. The emitter resistor really brought it back to life. It has so much more gain, I can dial in a lot more distortion, or roll back to just a tad. I love the nature or character of the distortion.

The input cap didn’t seem to make much difference. I also put in a small .01uf cap on the Q2 emitter resistor to ground to reduce the noise on the gain pot. In theory it should also improve HF response due to negating some of the inductance and non-linear artefacts inherent in the electrolytic bypass cap. Years ago, I used to perform mods on very high-end audio system electronics to minimise distortion, now I’m trying to design it in to the circuits.

I think it’s a print. I think this version should be called the Range Pig. It sounds great into my amp set clean; it provides a great distortion and tremendous presence. Into my Distortion + it provides a great creamy boost in presence & distortion in what I've tried.

Thanks so much for your feedback and suggestions. I really enjoy the exchange. I will draw out the schematic and see if I can get Marcos to host it on his site.

Regards,
Will

PS: In working on the schematic I had an idea.  :idea: The Q1 collector, what if a large value collector resistor is connected to the 9v supply. So a small amount of gain is occurring on this piggybacked transistor. It might add some additional non-linear character to the circuit at cutoff.

[petemoore]

Great name IMO [lol] !!! I'm glad you chose that one!!! I'm liking it...

[brian wenz]

Hello Hello Will--
  Great!  
Yeah, I like it with the 10K in there, too.  It seems "close to stock"  with the drive control  at about 75% - 80%  and then having the option for  MORE  guts  when turned towards full up.
I may lower the value of the .02  [.01 ??] cap on Q1's collector after playing the pedal through my stage gear for awhile.........it may have a bit too much  "oomph".........I dunno yet!
Looking forward to the new schematic.    See if you can through together a Piggy with the cap on the collector!
Brian.

[brett]

Thanks you guys.  This has been a very interesting thread.  Let us know when/where you post that schematic.

[brian wenz]

Hello Brett--
   Was wondering if you could let me know if you try the  "cap off of Q1 collector" trick.   I need as many opinions on that as I can get......sometimes I can't trust my ears 'cuz I've spent way too many years standing in front of Marshalls!
What amp are you playing through??
Thanks!
Brian.

[brett]

Hi.  The weekend went by without me getting to build the treble booster (I did build a modified Distortion+ and got half way thru a BluesBreaker tho).  

I've been interested in the cap to +ve supply method of controlling highs ever since I saw the "Rocket" and read reports about its smooth and creamy distortion.  Even without trying it, I'm sure that it is a good option, but it might take some sorting to work out the best value cap.

I play through an old MusicMan sixty five.  It's kinda like a Twin Reverb.  In the sixties both Eric Clapton and BB King used them (there's a classic photo of EC and BB jamming at the Whiskey Au GoGo in NYC, sitiing on a pair of them).  As for my playing, I definately have more enthusiasm than skill.  20 more years practice and I might "get it".

[Jim Jones]

I finally got around to building the Piggyback-booster or Range Pig if you like.

Hats off, Will -- this is a great effect!  I haven't played it extensively yet but I can see it becoming one of my favourites.  I wouldn't say it's a perfect duplicate of the germanium Rangemaster sound but it's damn close and in some ways superior.   BTW, I used a .01 input cap straight away - I do that with my Rangemaster as well.

I'd say the Range Pig doesn't have that same vowel-y, pukey kinda sound that my OC44 version gets.  I always think of Sabbath's first album for that sound...and play the B - Bm7 riff at the start of WASP/Behind The Wall of Sleep to see how pukey it's gonna be.  Very technical I know.  

I've never thought of the Rangemaster when thinking of Clapton's Beano tone - it always just sounded to me like a Les Paul into a cranked old Marshall.  I changed my mind with the Range Pig, though - it's the perfect device for that tone precisely because it doesn't do that pukey thing.

I haven't boxed up the Pig yet but even with the racket I get from having alligator clip leads everywhere I know it's going to be less noisy than a germ version.

Again - great stuff Will!  Thanks for sharing!

Jim

[brian wenz]

Hello Hello--
 Hey Jim--try a .0047 or a .0068 input cap to up the "puke" factor.   It'll get closer to Rangemaster  mid-range response.   Also, putting a cap. off of Q1 collector helps.
Brian.

[Jim Jones]

Hi Brian,

Reducing the input cap probably would help, but I'm able to get the puke with the germ version using a .01 so I thought I'd try that right away.  Hehehe, all this talk of puke - looks like we're turning this into a bulemia thread.  

I put the .022 between the Q1 collector and V+, I haven't tried it without so I'm not sure what influence it has on the circuit yet.

It's a great booster - I'm boxing it up tonight!

BTW, I used a pair of BC549C's - I wonder if lower gain transistors would be good to try?

Jim

[brian wenz]

Hello Jim--
 I used BC 182L in mine.....pretty low gain to start with [for silicon, anyway....].    
Yeah, the .oo68  or .0047 keeps things in the RM realm while a .01 gets more of a full-range  boost.
Brian.

[Jim Jones]

OK, I got it boxed up last night and tried a few things.  I was able to compare it side-by-side with my OC44 version for quick AB's.

Even with a .01 input cap in both pedals my OC44 pedal was brighter and grittier.  I changed the Piggyback to .0047 to see if it upped the puke factor but it just got thinner.  I returned to the .01 input cap and removed the .022 from the Q1 collector and V+ and that got it sounding more like the OC44 - maybe slightly thinner.  Tonight I'll try some different value caps there to see if I can tune it more to my liking.

I'd have to say the biggest difference between a germanium booster and the piggyback is the beautiful "rolled off guitar volume" clean sound.  With a germanium pedal that clean and chime just makes me smile ear-to-ear - it's an amazing thing.  That unfortunately just isn't there with the piggyback.  I'll try some monkeying with the bias before I right it off for rolled off clean, though.

Also, my OC44 pedal is gainier than the piggyback - I think I'll mess with the Q2 "faux 10K" voltage divider to get a bit more out of it.

I still think it's a great little booster!

Jim

[Doug H]

Also, my OC44 pedal is gainier than the piggyback - I think I'll mess with the Q2 "faux 10K" voltage divider to get a bit more out of it.

Jim

Try connecting the output cap directly to the collector of Q2. That will increase the gain considerably.

For rolled off chimey sounds, I like the simple Si Brian May Boost. It sounds better for that than any of the Ge rangemaster stuff I have tried.

Doug

[petemoore]

Or are we trying to use Ge's in a Piggyback TB.
 Starting with a 'close' Hfe Ge transistor for the active Q and use another Ge for the dummy Q...then tweek to tweek'd-ness and compare to the OC44 in a ckt?
 "Good Ge's being only somewhat more expensive and hard to find as Si's, this would make a useful area for experimentation?...Or did I misread and that's already what we're doing?

[Jim Jones]

Hi Doug,

Yeah, I might replace that "10K" with a pot and adjust to taste.  I'm thinking 8K2 and a 2K2 will probably be close enough for rock & roll.

Which Si May booster are you referring to?  I'd like to try it if it's a good as you say.  The rolled-off clean of the Ge blows me away -- if that can be obtained with Si all the better!

Jim

[Doug H]

It's the "Brian May Boost" at R.G.'s GEO site.

Doug

[will]

Hi,

Thanks for your comments and feedback on the Range Pig. I find this a great learning experience.

Out of interest what type of pickups are you using, when evaluating this? I’m using Fender standard strat single coils. I havent tried humbuckers on the Range Pig. I did find that humbuckers on the earlier incarnation didn't sound as good.

I’m not sure I fully understand the term chime, still new to this. Does that refer to the sweet bell like distortion?  I do like the Brian May Boost just before the heavy clipping takes place; the sound seems closer to my original schematic.  I really like the May Queen boost on Runoffgrove that has a fuzz-face type circuit after the treble boost, where the upper harmonics blooms into sweet harmonics. However, I would like to reduce the noise factor in the circuit.

Also the puke factor, Could that be as simple as moving the bias closer to the rails so the circuit is pushed more into cutoff. Changing the emitter to emitter resistor to a value less than 1K will make the transistors act more like germaniums near cutoff. When I tried that, considerable gain was lost that made it harder to push the transistors into clipping. I was wondering about adding a clean pre-gain stage to set-up the piggyback gain stage into overdrive. Another possible option is to create a pseudo Darlington where the second transistor is actually the piggybacked pair.

I originally used a .047 uf cap on input, which I thought was not bright enough. I tried .0047 uf cap and felt that sounded good on my set-up. The “faux voltage divider” was to avoid a volume control across a voltage drop, as well as to install a .01 uf cap parallel to R3 to roll off some of the highs. Pete’s suggestion of putting the cap from the unused collector to the 9 volt supply seemed to work just as well so I disconnected the .01 uf cap.

I will do some more tinkering on this.

Regards,
Will

[Doug H]

Hi,

Also the puke factor, Could that be as simple as moving the bias closer to the rails so the circuit is pushed more into cutoff.

I fooled around with a simple npn Si treble boost circuit on the breadboard about a week ago. It was derived from the vox treble boost circuit, which has a similar topology to the brian may boost and rangemaster. What I found was that in this case I really liked the harmonics better with the collector biased down around 2.5v (!). I went the opposite way from the (-)7 v used in the rangemaster kind of circuits, which sounded kind of ho-hum here. I'm not sure why this was, maybe npn vs pnp, or the bigger collector resistor I was using for higher gain (27k), etc.

In any case, what I learned was not to take that 7v collector bias as gospel. Move it around and listen to how it affects the sound. Using these Si npns and the piggybacking, you may find that "sweet spot" is in a completely different place than you expected it.

Doug

[Jim Jones]

Out of interest what type of pickups are you using, when evaluating this? I’m using Fender standard strat single coils. I havent tried humbuckers on the Range Pig. I did find that humbuckers on the earlier incarnation didn't sound as good.

Hi Will, yes I am using humbuckers.

I’m not sure I fully understand the term chime, still new to this. Does that refer to the sweet bell like distortion?

When I was referring to chime I meant the rolled off guitar volume clean sound.  I'm blown away at how good my Ge boosters do this.  It makes my neck humbucker sound like one of Jimi's single coils - it's a beautiful tone.  It's actually a way better clean than I get with my Rangemaster bypassed.  Why is that?    Fuzz Faces are good for that, too...[/quote]

Also the puke factor, Could that be as simple as moving the bias closer to the rails so the circuit is pushed more into cutoff.

That could be - I haven't played enough with the bias yet, but I will and let you know what I find out.

The “faux voltage divider” was to avoid a volume control across a voltage drop

That makes perfect sense, I hope you didn't think I was being snarky about that - it's not what I meant anyhow. I think I'll put a pot in there to find an optimum level for my tastes.

Thanks again,Will - it's a great circuit!

Jim