No knob lead boost

[Gus]

Just simmed a no control except for the a bypass switch lead boost

Controlled gain/EQ
Two high beta/hfe NPN transistors
Bootstrapped input so no need for a JFET

Any interest?

[knutolai]

Bootstrapped input so no need for a JFET

Is that for getting higher input Z? I'd be interested to see it !

[deafbutpicky]

bootstrapped EQ? Shure, go ahead...

[thelonious]

Me three.

[Shoeman]

Ayuh,  let's see it.

[duck_arse]

I've got a box that'll fit, and I'm "doing" boosts at the moment.

[Kipper4]

Yes please me too Gus.

[Gus]

I have not built this this is a sim


Note the 220pf input cap
the first stage is bootstrapped for high input resistance
C1, C3, C4, R12,and more are adjusting points
This is a simmed version with a simple single coil guitar sim
For more mids at lower gain omit C3, R6
More mids and more gain adjust C3 (10uf looked good in a sim)and/or adjust R6
Adjust C4 for the lowpass filter
Adjust R12 to change the resistive load on the guitar
The operating points of the transistors are a compromise for a 9VDC power supply and standard resistor values
R3 and R4 bias both stages don't reduce R4 value under 100K if you want to adjust the biasing
I have not built this
The values might be good starting points for a bypass switch only lead boost
Note the frequency the curves cross
You don't need jfets for high input resistance

[Davelectro]

Thanks for sharing your ideas.

What is the input impedance in this particular case?

It would be great if you show us how to get a specific Zin. Say, 1M.

[Gus]

Thanks for sharing your ideas.

What is the input impedance in this particular case?

It would be great if you show us how to get a specific Zin. Say, 1M.

Not an easy answer
this depends on the input cap size
and the EQ in the 1st stage emitter leg
and frequency

But try a 4.7meg for R12

[Kipper4]

Sweet Gus looks like a breadboard candidate.
If I was to add an output attenuation pot.
Would a 100k A be good? To try to keep the output impedance up.

[Gus]

A 100K volume control would work well and be the same when turned to full volume.
However I have built something like this in the past for friends and the gains/EQ I selected seems to work well with no controls as a lead boost.

This is an effect that can sound good or not so good depending on the guitar and amp. 
I believe I posted good starting values to try and then you can adjust to what you want

[Kipper4]

Thanks man.
I'd be running into a Fender pj but for guitars I got a good choice from a mim strat to a hotter humbucker prs .
So I guess I can experiment while it's on the breadboard and adjust for differant guitars.
Thanks

[Kipper4]

Nice clean boost man thanks.
I'll leave it on the BB for now and try some of the tweeks you suggested over the next few days.
edit
i was fresh out of 5089 so i used 5088

[duck_arse]

here is my first paperless vero layout. the circuit numbering has been changed to match layout. layout is not verified.



[edit: ] original deleted, amended layout posted

[Kipper4]

All looks good to me. Thanks Duck Arse.
I have this on the BB I'm gonna mess with the suggested mods and see which I like best with my set up. Waiting on some 5089s but so far so good with the 5088s.

[duck_arse]

thaks kipper. all my layouts are mimimal size, so resistors go on-end, no mounting holes provided. if I stop looking at this, I'll stop seeing changes I can make .... C5 for instance .....

[Kipper4]

Yer I know what you mean but there has to be a cut off point where its not worth spending anymore time on the layout without a significant effiency differance.

[Kipper4]

I prefer it with 10uf C3 cap.
It might be pscho acoustic though.
I'll run up a DIYLC Pref layout and get back.
Thanks Gus

[pinkjimiphoton]

interesting component choices gus,
i like how most are standard values.

make any appreciable difference using 100k on both sides of the voltage divider?

all my stuff is packed at the moment, or i'd definitely have a play with it.

will various q2's bias up alright tho with no c resistor? or is that why the e bypass is so big?

cool design, look forward to hearing it!