tagboardeffects Triple Wreck boost question

[m37a]

Okay, I thought an emitter follower was a boost but it's actually a buffer? Sorry learning as I go...

anyways, I tried simulating this circuit based on the original layout and values. It doesn't look right to me (although to be fair I am not sure what the output signal is supposed to look like).

Here is the simulated circuit:
http://tinyurl.com/y7q7vx44

[antonis]

Okay, I thought an emitter follower was a boost but it's actually a buffer? Sorry learning as I go...

Nothing bad with learning and no need for apologise at all...!!! 
(γηράσκουμε αεί διδασκόμενοι or we all live and learn from our mistakes..)

(Good intensions irony is a way for sneering ourselves when said guffs much bigger than yours..) 

[m37a]

I compared the vero layout again and there is a trace cut hidden under the 47k resister, so the 1m resister is not connected to the 10k resister to ground.

I have updated the schematic:


simulation:
http://tinyurl.com/ydg7hs3r

I corrected this on my breadboard but the signal leaving the collector is still quieter that the original signal and distorted 

[m37a]

I compared the tagboardeffects boost with the boost of the Madbeans Upper Decker. They are almost identical except the madbeans has the 100k resister to ground before the transister base. I will try this later and see what results I end up with. Another member PMed me and says that they also have built this circuit, and it does not boost the volume at all, just make the signal more fuzzy. So perhaps there is nothing wrong with my circuit after all???

[antonis]

Let's face some "discrepancies" between theory & reality..

The above circuit consists of a BJT amplifier followed by a BMπ style tonestack..

First stage amplifies signal about 33dB whereas second stage attenuates it about 7dB (overall) and about 6.5dB at the notch (-13.5dB total)..
(more or less, they're just rough approximations..)

From the above it's clear you'll have to get a boosted signal on the OUT - but you already have a amplified (to the top of headroom) signal on the IN, so you can't get more Volume but only more Distortion..
(more "square" waveform..)

What Boost actually does is to add some "complexion" (colour/hue/timbre) of your choice in conjunction with the 3 band EQ of WTW..

Now to the circuit values & settings:
Changing the 10k resistor of the HPF with a 100k one you result in lowering the corner frequency by a factor of 10 (1/2π*R*C)
(from about 1.6kHz to about 160Hz..) actually overlying LPF impact (corner frequency at about 340 Hz)..
(there should be a reasonable bandwidth between HPF & LPF cut-off frequency margins, e.g. a mid scoop at 800Hz..)

As for BJT bias, I prefer voltage divider base bias although I don't adopt the specific values..
(Base at 800mV, Emitter at 150mV, Collector current 150plus μΑ, Collector voltage at about 2V - which values may dramatically alter with only a slight V_BE variation - 50mV "swing" on V_BE results in almost 2.5V on Collector voltage..)

This kind of setting Q-point may easily result in asymmetrical boost/clip..
(which may be desirable but definately NOT controllable, in the mean of accurately setting it..) 

[m37a]

you already have a amplified (to the top of headroom) signal on the IN, so you can't get more Volume but only more Distortion..

I am confused by this. I believe this circuit is supposed to be wired pre-WTW so the signal shouldn't be already "maxed" should it?

[antonis]

You may place it pre-WTW if you like but it's wired after-WTW in the original pedal, isn't it..??
(both circuits have an anti-pop 1M input resistor for independent activation, if that's what puzzling you..)

The about 60k input impedance of Booster isn't a very "convenient" value, is it..??

P.S.
Maybe I'm totally wrong and you're right.. 
(can some other guy enlighten us..??)