"Simple Boost" 1st schem, help required !

[MartyMart]

This is based on lots of stuff found here etc, so not a world beating idea !
just my first attempt, could I perhaps add diodes to ground for an MXR type distortion?, this just pushes the level up nice infront of my Tube amp !

No drawing package as yet, so sorry its a bit "scruffy"
NE5534AP  seems to sound real nice, but any good single op-amp will do.
Any mistakes/improvements guys ??

Thanks,
Marty.

http://www.pbase.com/image/36770838

[RLBJR65]

I use windows paint to draw schems. just draw up your own set or borrow
them from other schems. Cut and paste all of the different symbols and save them on one sheet then you never have to do it again.

[MartyMart]

I think i've got an impedance miss-match, if i roll back the guitar's pot the output almost dissapears, and gets very "tinny"   Help !!
Only seems to work well with guitar on full and vol pot on 25% !!


Marty.

[Paul Perry (Frostwave)]

Looking at the schem, the + and - of the op amp seem switched from what I would expect.

[RDV]

If you increase R1 to 100k, then jump up the FB resistor also, you'll probably get what you're looking for. Your FB loop should be on the inverting side also.

RDV

[MartyMart]

Thanks guys,
Yes it does look like I've got it the wrong way around, it sounds more like a small pre-amp at the moment, pushing out way too much signal for an SS amps front end, makes the tube amp "crunch" up though !!
I'll try the changes out, thanks Ricky, and some diodes to ground could be nice.

Marty.

[MartyMart]

I found this to work quite well for a nice boost, R1 became 51k and R2 became 330k, also tried a 4k7 pot instead of 1k
I swopped the 1uf cans to Poly (avx) and the 10uf to a tantalum, its got a very high quality "hi-fi" sound now, thanks for the tips !!

Marty.

[brian wenz]

Hello Marty--
  Are you going to post a revised schematic???
  Looks good......the hand-drawn schematic is very "readable" !
Brian.

[MartyMart]

Thanks Brian,
I'm still "playing" with it, but you can try those changes if you like, i'd love to know what someone else thinks this sounds like ?

Marty.

[brian wenz]

Hi Marty--
  I could use some op-amp work 'cuz that's an area I'm really weak in....all those pinouts scare me!   I really wanna build the DeArmond Square Wave, too , but it's got one of those "scary" op-amps in it as well!
Brian

[Paul Perry (Frostwave)]

Brian, those op amps are a lot LESS scary thatn transistors, in my opinion. Why? Because, if you have 1,000 TL072s, you can swap then and it makes no difference whatever. But with transistors, or (god forbid) fets... :x

[bobbletrox]

I reckon it'd be cool to make a two transistor fuzz with one of those arrays that contain two matched transistors.  ICs are asymmetrical.

[MartyMart]

OK, a Question and perhaps this is to do with not using the inverted side for the feedback loop, but here goes....
The boost circuit works real well with the guitar vol pot up full, but when i back off just a little, the sound really "thins out" like i've rolled off all the bottom and middle !!   Any ideas `??
Would like to get this right, as i have another schem on the way, a bit like a TS circuit but simplified and using two LED's for "drive", no tone control just a great "clean" or "crunchy" booster. . . . .

Thanks in advance,
Marty.

[brian wenz]

Hello Hello Paul--
      Yeah, very true!   What scares me is the op amp has got all those legs........all kinds of ways to solder the wrong thing to the wrong thing!
I just haven't had enough experience to understand how to wire the things up properly.
 Hi Marty--  The Fuzz Face circuit is like that, too.  Maybe not as dramatic as in yer circuit, but the highs seem to get more present when  you back off the volume control.
Brian.