Can I build this without the diode switch - or would it be as easy to go ahead?

[steveyraff]

Hey guys,

I have built this circuit for a friend. I am trying to fit it all into a 1590B as others have said they managed it. I was wondering if it would be more convenient and space efficient to leave out the diode switch, or do you reckon it'd just be easier in the long run to put it in?

I guess I'm a little apprehensive as I've never attempted a diode switch before. I have everything I need to do it though, if it'll fit. Its hard to tell from the diagram, are the diode legs just soldered directly together, where the diagram shows blue spots? Or do I need to actually put little jumper wires between them all?

Sorry about the silly questions.
http://tagboardeffects.blogspot.co.uk/2012/10/xotic-bb-preamp.html

[Granny Gremlin]

The switch changes what the clipping diode config is (in the layout it says both options use 1N4148s, the switch chooses between a single or double rev polarity pairs).  You can pick one (bit of clipping or a lot of clipping respectively) and not provide the option for the other; totally reasonable to save space.

You don't jumper anything, simply connect the diodes (either the single or the double pair) to the same place that the middle 2 lugs of the switch go (Drive1 and Sw1-5), you end up with this instead of the switch diagram (single pair shown) as shown in the layout pic:



            _____diode|___
Drive 1____|              |____SW1-5
           |____|diode____|


Frankly, I dunno why this layout requires 6 of the same diode when only 4 (or 2 depending on sw setting) are in use at any given time.  If you do use the switch, I'd rewire it so a single pair is out front the switch (always in use) and the switch only kicks in the second pair. 

[steveyraff]

Hmm, thanks man.

Maybe I should just go with the switch, if its not much extra bother. I was sort of thinking in terms of damage limitation lol. It looks like something I'd mess up. So if I was following that diagram, I'd just solder the legs of D1 and D2 together, in that orientation? Then have them both going to the top lugs of the switch?

[Granny Gremlin]

Maybe I should just go with the switch, if its not much extra bother.

It is a bit more bother (to do right - see below re daughter board for structural integrity)

So if I was following that diagram, I'd just solder the legs of D1 and D2 together in that orientation?

Yes. Opposite just as the pairs in the pics below.

Then have them both going to the top lugs of the switch?

No switch in the above ASCII diagram case; the lead labelled "SW1-5" goes to the spot on the board with the same label.

If you do go with the switch, consider simplifying the switch as I mentioned earlier (eliminating 2 diodes).  You can even get away with using a SPST vs DPDT (though if you do use a DPDT, 1 diode from each pair on each Pole, it would help with structural integrity of the assembly; otherwise I recommend making a little daughter board out of some scrap perf):



or



See this pic for an example of what I mean by "daughter board" above - the bit of perf attached to the back of the slide switch top middle below:



Notice how I didn't bother with such a daughter board on the cap switch stomp (top right) since both of the caps have both leads attached to switch lugs there's no risk of the wire getting pulled and damaging them.

[steveyraff]

Hey thanks for that man. Very helpful diagrams!

I'm just looking at the switch I have for this. I think it might be the wrong kind. It's labelled as a DPDT mini toggle (on) - off - (on). However, it always goes back to the middle position. Like its momentary and not latching?

What is the kind of switch I do require?

[steveyraff]

http://www.bitsbox.co.uk/index.php?main_page=product_info&cPath=116_127&products_id=879

This, I guess?

EDIT: Found one of these anyway.

[Granny Gremlin]

Hey thanks for that man. Very helpful diagrams!

I'm just looking at the switch I have for this. I think it might be the wrong kind. It's labelled as a DPDT mini toggle (on) - off - (on). However, it always goes back to the middle position. Like its momentary and not latching?

What is the kind of switch I do require?

Yeah, either DPDT or SPST will work (as above) but (sorry this is my ommission) MUST be ON/ON for my wiring.  I didn't notice the ON/OFF/ON on the layout diagram - that's why they use 6 diodes vs 4; the third option (off position) = clean/no clipping diodes.  Yeah that's better - do it their way; you have the right switch.  Sorry about the brain fart.

What I said about removing the switch still stands except you can just jumper it for clean only mode )replace the parallel diodes in my ASCII diagraqm with plain wire).  Again, sorry, - this is what happens when you don't check out a layout properly before running your mouth.    It is handy to have a clean option on the switch, but I figured dialing back the Drive control would do the same thing so why bother.... and was wrong.

[steveyraff]

No need for apologies at all! You've been most helpful anyway.

I've drilled it out for the switch anyway and it seems I might just about fit it all in there. We'll see!

Many thanks for your time.

[duck_arse]

I'm not looking at links either, but this pictured wiring, if used with a centre-off spdt, has no diodes in centre position, 2 diodes one way, and 4 the other. isn't that what you want? (switch problems are easier if you draw the circuit diagram.)

[Granny Gremlin]

Yes, I brain farted and thought the original layout was with an on/on (some diodes always in) noticed later that this wasn't so but didn't change the pics in the old post.