Hello Hello--
 Built up Will's Piggyback TB and have been soundchecking it against my germ. Rangemaster clone [OC44]  and silicon Vox Treble Booster [with a couple of mods].   I used two BC182L trannys and it does not have the mid-range "honk" of either of my other TBs.  Tried messing with the values of some of the resistors in the circuit  [150K and both 10Ks] with no results.  I don't expect anything to have exactly the same squash and honk of the germanium circuit but adding more mids to the Piggyback would be great.  By the way, increasing the input cap value turns it into a good full-range booster.
Will--- watta ya think about putting more mids in this circuit??
Brian.

Hi.  Comparing my piggybacked Si fuzzface with its Ge counterpart, I've concluded that it's the lack of highs in the Ge fuzzface that make its midrange seem so strong.  To knock off some highs from the piggybacked design, I'm playing with caps (around 0.0022uF) to ground prior to the volume control (the MXR distortion+ has a similar 0.001uF cap).

cheers

PS to get a more germ-like sound, have you tried using a small resistor between the piggybacked emitters?  Say 1k or less.

Hello Brett--
 So, the cap would go after the 1 meg and before the output jack [in the Piggyback TB circuit] ?
Also, there's already a 10K res between the emitters of the Treble Booster, so are you saying to add another res?
Thanks for the tips!
Brian.

Sorry for being obscure.
The cap should go before (circuit side) the volume pot.  (If in doubt, check the 0.001uF cap in the Distortion+ schematic at tonepad.com)

I was suggesting replacing the 10k resistor with 1k (or even less).  With smaller resistors between their emitters the pair of transistors behave less linearly (ie more like germanium).  There's a kind of trade-off between gain and non-linearity.  With a 10k resistor I suspect you've got high gain and a fairly linear response (ie more the "Si" sound).  Maybe start with 1k and see if that makes a noticeable difference.  If not, try 100 ohms.
cheers

Hello Hello Brett--
 O.K., got it!  Thanks!
Have you built the PB TB??
Brian.

My only piggyback experience so far is a Fuzzface (Miss Piggy).  But 2 more diecast boxes arrived in the post today, so I'm thinking that this weekend I'm gunna build a Treble Booster, ToneBender(MkII?) or a Rangemaster (or all three).

Cheers

Quote from: brian wenz
Have you built the PB TB??
Brian.

Is there a schematic for this? How's it sound?

Thanks,
Bill

Marcos' Munky's Site...schematics ... at the bottom i think...
 I think it sounds great and is worthy of building, using and diddling  with.
  For those of us who like tweeking [you better like it lol] this extra Q and resistor  where there was one transistor makes for added pleasures!!! lol !!!

Hello Hello Brett--
  Is there a schematic for Miss Piggy??   [Maybe I missed something....]
I'm getting ready to try some different caps out in the Piggyback TB circuit so I'll let you know thr results.
Brian.

Hello Hello Brett--
    I put a .022  cap between Q1 collector [the open one] and 9v+.   The .022 may seem a little big, but it sure brought the whole "feel" of the circuit  alot closer to my germanium [OC44] .  More warmth and mid-range "honk" then before.  Still haven't changed the 10K, though.
Brian.

The layout for piggybacking a fuzzface, the "miss Piggy", is both in a thread called "piggyabking trannies for low gain" and here;
http://members.optusnet.com.au/~jethro.dog/mypic105.jpg
cheers

Hello Brett--
Thanks!  I'll go back and read the thread.
Brian.

Hi,

I'm quite enjoying this thread. I appreciate Brian's comparison to his Rangemaster clone,  especially the missing squash & mid boost honk.  I tried Brett's suggestion of reducing the resistor between the piggybacked transistors to approx. 900ohms and I tried a 470pf cap between the collector and base of Q2, to roll of some highs, and rebiased the circuit last night after reading the exchange. Quite a different sound, It was late at night so I could only try it out at low volume. My initial observations were: I think the 470pf cap rolled off too much highs so a bit of experimentation is in order. There was a huge loss of gain so I am wondering if I should try higher gain transistors or increase the emitter to emitter resistor to say 2K.

I really like the sound of the original, so I'm planning on boxing the original for jamming & gigging and build another and refine to get closer to the Rangemaster. (get the best of both)

Here is the link for the original schematic
http://www.geocities.com/munkydiy/piggybacktrebleboost.gif

Other thoughts: What type of guitar pickup are you using as it seems to make a huge difference in the sound. My circuit sounds really good with my 89 American Standard Strat single coils. The circuit sounds so so with my 89 Japanese Strat with the humbucker in the bridge. When you split the humbucker into single coil the magic comes back. I am assuming this effect is directly coupled to the guitar any non true bypassed device in front will really change the response.

There is a real interesting article about the effects of input impedance and the capacitance of the cables changing the resonance peak for guitar pickups. It stated that Stratocaster single coils and Gibson Humbuckers have very different resonant peaks. "A 1000pF cable capacitance shifts down the Strat pickups theoretical resonant peak at 10KHz to 3.7kHz - and higher capacitance loads will shift it down further."
http://goran.tangring.com/index-filer/Pickup-cabletheory.htm. So maybe to get the midrange peak for a single coil is just to use a 3.3nF cap on input to ground and use a larger input resistance for larger peak, the resonance would be centered close to 1Khz.  

There are may options to modify the circuit to roll off the highs. A cap between:  input to ground; output to ground; bypass the collector resistor(collector to 9volt), collector to base of Q2. Which is best and what value to try?? Perhaps a simple tone control on the output.

Regards,
Will

QuoteI think the 470pf cap rolled off too much highs

I've previously used either 100pF (mild) or 220pF(substantial) base-collector caps for rolling off highs.  I've used both ceramic and styro caps, and the difference between them is negligible.  470pF or 1nF from base to ground might be a good alternative.

Hello Hullo Will--
 I'm glad you've been working behind the scenes some more!!  
Here's what I've done so far on mine--- input cap is .0068, cap between Q1 collector and 9v is .022.   Everything else is stock.
These mods don't seem to have taken much gain away, either, but I'd like to get your experience on this as well.   Oh, I used two BC182L trannys in mine, too, so that would make a difference in overall sound.
I like the sound of the original circuit, too!
Thanks-
Brian.

Hi Brian & Brett,

Brian, I had never even considered putting the cap between the unused collector and 9v.  I guess since the cap blocks all DC and is essentially equivalent to attaching the cap to ground. I wonder what is really going on in the gate - collector portion of the Q1 transistor?

Since I cut off the collector lead for Q1 transistor I’m going to try a 100pF base-collector cap on a switch for a mild rolling off highs.

Got to go, and walk the dog. Then heat up some solder!

Thanks,
Will

Hello Hullo--
 Yeah, I didn't  know WHAT the effect of that .022 cap was going to be.  
Actually, I'm not sure if it's adding any mids or just  subtracting highs.  Lemme know after the solder cools off....
Brian.

Hi Brian,

I just tried 120pf mica cap across the base and collector to Q2 with a switch it didn’t seem to cut very much so I added another 200pf ceramic still not much. I’m wondering last night when I thought the 470pf ceramic was too much. It was probably my amp's volume controls loosing the highs because they were set so low.

I tried using my headphone amp to hear the differences. Actually my wife suggested it, as she is not a big fan of the electric guitar when she is tried. The headphone amp is very flat in freq response. Wow it is really bright, but it does sound really good in the neck pick-up. I think I will try a different tact.

The caps across the base & collector seem to reduce the mild clipping on the peaks. I'm now thinking that I should try to increase hfe (gain) with a larger emitter-to-emitter resistor (perhaps 1.5K) and cut out the highs. I also want to cut the output volume a bit. I might try replacing the 10K collector resistor with two 5K resistors and put the output cap between the 2 resistors like the fuzz faces.

Also I wonder the effect of putting a small cap across the piggybacked emitter-to-emitter resistor. I think it should change the gain of the transistors by frequency. Less gain for the higher frequency. I’m not sure the value I should start with. I do believe the circuits gain right now is limited by the piggybacked pair. However, I think I will hold off on that idea right now.

I was also thinking the Rangemaster had approx 12K input resistance that means it reduces the effect of the pick-up resonance so the circuit would work well with a greater range of pick-up types. Hummm :?

Regards,
Will

Hello Will--
   Have you tried putting a cap from Q1 collector to 9v  yet??   I'm  real interested to get your  opinion on this.
Brian.

Hi Brian,

Quote from: brian wenzHave you tried putting a cap from Q1 collector to 9v yet??   I’m real interested to get your opinion on this.

No, silly me I cut off the collector right next to the body of the transistor.  :oops:  I didn’t want to pick up any radio frequency so I try not to create any antennas. It probably wouldn’t have made any difference.

I did the mods in my previous message I replaced the 10K Q2 collector resistor with two 5.56K resistors and moved the output cap between the two resistors. This cut output volume in half. I changed the emitter-to-emitter resistor to approx 1.5K. This increased the gain somewhat so I can get a touch more distortion. I put in a .01uf cap in parallel with the top 1/2 of the collector resistor (from the output cap to the 9v). This cut the highs more than the previous arrangement. However I left in the 120pf cap from Q2 base to collector still on the switch. Now you can tell its there as it sounds smother with it connected.  I'm still wondering if I need more highs cut.

It sounds pretty good in my headphone amplifier. I set the bias by ear. It sounds pretty clean soft picking, as you pick harder it gets distorted (subtle yet pleasing) when you hit really hard it gets louder with kind of a splat sounding distortion. I'm not sure how a good rangemaster sounds into a clean amp. I can imagine into a distorted tube amp. The louder splat distortion (It's a terrible description I know) would probably get a creamier but I'm guessing. I also am not sure of how much treble should be cut.

I might try later replacing my Q1 transistor with an 2N5089 to increase the gain. Then I can try putting a cap from the collector to the 9v supply.

Regards,
Will