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BJT push pull amp stage EDIT: sim audio added !

Started by Steben, October 09, 2021, 06:37:35 AM

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Steben

October 09, 2021, 06:37:35 AM Last Edit: October 09, 2021, 12:01:49 PM by Steben
Hi Guys.

Just wanted to share an experiment i did in Spice with a BJT push pull kind of circuit.
It is based on driving a complementary BJT pair into their base emitter cut off (kind of range master setup) and going beyond.

Thing is, not only I searched for a smoother transition into non linearity, when you drive harder, cross over comes into play where the sum of both transistors is getting zero.
AMP like!






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Steben

#1
October 09, 2021, 12:00:07 PM Last Edit: October 09, 2021, 12:02:51 PM by Steben
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GibsonGM

#2
October 09, 2021, 01:00:24 PM
That's pretty cool, I see a circuit with power amp distortion coming! :) 
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MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

antonis

#3
October 09, 2021, 04:19:31 PM
We (the Greeks) used to impale bad fortune tellers, Sir Mike..!!  :icon_mrgreen:
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

GibsonGM

#4
October 09, 2021, 05:33:30 PM
Quote from: antonis on October 09, 2021, 04:19:31 PM
We (the Greeks) used to impale bad fortune tellers, Sir Mike..!!  :icon_mrgreen:

I may have to BB one myself, in order to avoid sharing that fate!   I thought that was the Romanians, by the way - you guys did that too?
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MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

FiveseveN

#5
October 10, 2021, 02:41:17 AM Last Edit: October 10, 2021, 10:54:11 AM by GibsonGM
Quote from: GibsonGM on October 09, 2021, 05:33:30 PM
I thought that was the Romanians

Geez, one guy gets creative with his torture killings and we all get a bad rap  :icon_biggrin:
On the topic of poweramp sims, how about a "class A/B" or symmetry control?


Quote from: R.G. on July 31, 2018, 10:34:30 PMDoes the circuit sound better when oriented to magnetic north under a pyramid?

GibsonGM

#6
October 10, 2021, 10:53:29 AM Last Edit: October 10, 2021, 12:36:42 PM by GibsonGM
No fear - one day the US may be remembered for Jeffrey Dahmer...  :icon_eek:

Back to topic - how would we modify the symmetry here? A pot at the transistor bases, like a 'blend' control?   < edited for what I intended to say
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MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

Steben

#7
October 10, 2021, 11:57:02 AM
Quote from: GibsonGM on October 10, 2021, 10:53:29 AM
No fear - one day the US may be remembered for Jeffrey Dahmer...  :icon_eek:

Back to topic - how would we modify the symmetry here? A pot before the diodes, like a 'blend' control?

Mismatched transistors
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GibsonGM

#8
October 10, 2021, 12:28:06 PM
Ah, 'complementary pair' probably covers that aspect...  ;)   
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MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

Fancy Lime

#9
October 10, 2021, 03:43:40 PM
Quote from: antonis on October 09, 2021, 04:19:31 PM
We (the Greeks) used to impale bad fortune tellers, Sir Mike..!!  :icon_mrgreen:

Would that be for tellers of bad fortune or for those bad at fortune telling? Or both?

Quote from: GibsonGM on October 10, 2021, 10:53:29 AM
No fear - one day the US may be remembered for Jeffrey Dahmer...  :icon_eek:
...
I thought the USAmerican stereotype was that cannibals are German, no? I seem to remember a bunch such SNL skits.

@Steben
Cool circuit. Sounds really nice!

Andy
My dry, sweaty foot had become the source of one of the most disturbing cases of chemical-based crime within my home country.

A cider a day keeps the lobster away, bucko!

GibsonGM

#10
October 10, 2021, 05:32:08 PM
I haven't heard that one, about the Germans, Andy...but I haven't seen SNL since Will Ferrell was on there,LOL.   News to me!  Tho Hans & Franz bring back some fond memories from parties and whatnot...

So - for this 'power amp sim' kind of thing...what would sound good as a preamp do you suppose?
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MXR Dist +, TS9/808, Easyvibe, Big Muff Pi, Blues Breaker, Guv'nor.  MOSFace, MOS Boost,  BJT boosts - LPB-2, buffers, Phuncgnosis, FF, Orange Sunshine & others, Bazz Fuss, Tonemender, Little Gem, Orange Squeezer, Ruby Tuby, filters, octaves, trems...

bowanderror

#11
October 11, 2021, 05:59:01 PM
If you're looking for LESS crossover distortion (rather than more), I saw this North Coast Synthesis build doc with a class-B output stage. See page 24 for circuit analysis and methods for reducing crossover distortion. Not sure if it is applicable here (it's for a VCA & uses a current mirror on the input), but it's at least an interesting read!

dschwartz

#12
October 12, 2021, 08:04:22 PM
Interesting, did you breadboarded it, or the audios are from ltspice .wav simulation?
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Steben

#13
October 13, 2021, 07:33:50 AM
Quote from: dschwartz on October 12, 2021, 08:04:22 PM
Interesting, did you breadboarded it, or the audios are from ltspice .wav simulation?

sim
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