Behringer SF300 mods

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
Post Reply
User avatar
Hanky-
Information
Posts: 36
Joined: 22 Jul 2015, 07:51
Has thanked: 2 times
Been thanked: 6 times

Post by Hanky- »

Got my pedal delivered today, started checking the circuit with the schematic & so far found these values to be different from the Boss FZ2.

R23= 47k
R3= 27k
R10= 1.8k
C26= 1.5nF
R64= 56k
R61= 56k
[C32= 150nF Ceramic type]

These when compared to the FZ2 should be as follows:
R23= 10k
R3= 100k
R10= 2.9k
C26= 47pF
R64= 47k
R61= 47k
[C32= 150n Tantalum type]

The R64 & R61 are part of the buffer portion of the circuit. I didn't notice the buffer to be degrading so these can be left alone. I had not noticed the C26 being different so when I went ahead with switch the values to Boss specs, the unit sounded messed up, had to go back to stock setup. I don't have a 47pF cap at hand for the moment, will have to wait till it arrives. Besides these, I haven't found anything else that's different. By default the sf300 sounds very good, 90% like the FZ2 in the vids I could source online.

A word of caution, behringer tends to glue their smd components, it's not difficult to get them out with two soldering irons, just takes a little longer. Also you will need two irons to get these off the board without a risk of uprooting the solder pads.

Here's a pic I've attached to locate these components on board.
Attachments
SF300-001.jpg

User avatar
Hanky-
Information
Posts: 36
Joined: 22 Jul 2015, 07:51
Has thanked: 2 times
Been thanked: 6 times

Post by Hanky- »

Well I need to update this thread, you need to change C26 to 47p, R61 & R64 to 47k. That's it, everything else is correct, ignore my findings above, you can check the FZ2 thread for my post for more details, dont see the need to explain the problem again.

Also the red glue dots on either sides of the components, use a pair of tweezers to remove them gently first, then try to unsoder.

Man the prices on used FZ have soared high lately, found listings upto $400+.

Goodluck!

User avatar
MF_Kitten
Information
Posts: 2
Joined: 08 Jul 2019, 11:37

Post by MF_Kitten »

What would you say actually changed?

User avatar
uncleboko
Cap Cooler
Information
Posts: 464
Joined: 25 Mar 2008, 20:19
Has thanked: 56 times
Been thanked: 29 times

Post by uncleboko »

MF_Kitten wrote: 04 Oct 2020, 15:42 What would you say actually changed?
Exactly my thought!

User avatar
Hanky-
Information
Posts: 36
Joined: 22 Jul 2015, 07:51
Has thanked: 2 times
Been thanked: 6 times

Post by Hanky- »

It's been awhile since I had done the mods. If I remember correctly the Lows & Highs changed with the mods, the amount of gain changed or not I can't remember, it made it sound more modern. I can't remember more now because I don't use this pedal frequently. It was a single 1n5 cap(there's only one cap of this value on the board) that I changed to 47pF. This alone will get it 99% there to the FZ2.

I did change the buffer circuit resistors to FZ2 values too. I liked the changes there as well, the bypass sound now is sounding more balanced, before it was touch too treble influenced with less bass.

With these three component changes it becomes a exact clone of FZ2 minus the type of caps used in the boss.

Next up mods will be to try 1N34A pair of diodes in place of the stock ones or try to get a switch in there to toggle between the stock ones & the germanium ones. Getting a mini DPDT toggle is tricky nowadays, fitting it in there will be even more tricky.

Post Reply