AC128 treble/mid booster

Keefy

I have a couple of AC128 transistors in my stash - I think I took them from a dead transistor radio maybe 35 years ago (I’m well old). I fancy building a treble booster with a mid-boost option - any favourite circuits?

LastMantra

I suppose you could make a rangemaster type with switchable input caps. 

Keefy

LastMantra said:

I suppose you could make a rangemaster type with switchable input caps. 

Exactly the sort of thing I’m thinking of.

PeteC

Rangemaster every time.  

Have a look at RG Keens article on testing for leakage though - the transistors need to be good. 

Keefy

PeteC said:

Rangemaster every time.  

Have a look at RG Keens article on testing for leakage though - the transistors need to be good. 

Cheers, will do. In fact I think I have  schematic for a leakage tester somewhere.

LastMantra

Keefy said:

LastMantra said:

I suppose you could make a rangemaster type with switchable input caps. 

Exactly the sort of thing I’m thinking of.

I've made a couple of rangemasters with AC128's. One with standard component values and one with slightly different, can't remember exactly think it's just the one cap, which gives less treble. A bit smoother. Sounds great with my strat in particular. 
I always meant to do a switchable one but haven't got round to it yet.

springhead

Rangemaster but with two input caps and a pot to blend between them. Stock Rangemaster at one end of travel and more of a flat boost at the other, depending on the values you use. I’ve built a couple like this and done the same arrangement on half a dozen fuzz faces. Works well. 

Keefy

Cheers chaps. I probably need to test my AC128s first so check they don't leak like sieves!

DannyP

I made a Rangemaster clone with a rotary switch looping in different value caps for C1. It achieves cocked wah tones in the lower settings.

I also made FuzzDog's Naga Viper clone, which is much more usable and 'normal' sounding as a frequency adjustable treble boost, but the Rangemaster with multiple capacitors is more fun!

PeteC

Switchable input caps are cool on treble boosts and fuzzes .  One of my fave fuzz pedals is Joe Gagans Easyface which has switchable input caps - cant remember whether it was like this in the schematic or whether i added them - anyway worth a shot.    Having said all that a stock rangemaster into an EF86 input stage is a marriage made in heaven.  

LastMantra

I once made a distortion pedal from what started out as basically a rangemaster into an EHX muff fuzz that I thought was rather good. Vintage-y, overdrive-y, fuzz-y dirt with a big sound and lots of sustain.

I gave it to a friend when he visited from Sweden to use in his band.
Building it again is another project I've not got round to.