switchable output transformers on gssl

regularjohn

Well-known member
Joined
Jan 23, 2009
Messages
321
Reaction score
2
Location
Raleigh, NC
I've been searching for about an hour now and I can't find anything on this.

I want to make the output transformers in my gssl switchable, so that I can switch back and forth between transformer and transformerless output.  I'm thinking a 4PDT switch coming off the gssl pcb might work, with the different output resistors on the switch leading to the respective outputs.

Basically what I'm concerned about is that with this configuration both output paths would remain connected to the same XLR jacks and it would be the output path of the pcb that would change (if that makes sense).  Is there going to be a impedance loading problem doing it this way?  Because if I was in transformerless mode, the secondary of the transformer would still be connected to the xlr, and vice versa.

What kind of switch or relay could I use that would switch both sides of the transformer connection if I can't do it as I described above?

Any advice on doing this mod?  

Thanks so much!
 

bdubya

Well-known member
Joined
Nov 11, 2008
Messages
220
Reaction score
0
I suppose you could just get another switch with more decks to accomodate the extra actions necessary, or an additional deck for your switch, if its that "expandable" type, and use it to break those extra connections that you're concerned about. 
 

regularjohn

Well-known member
Joined
Jan 23, 2009
Messages
321
Reaction score
2
Location
Raleigh, NC
Yeah, I was kinda hoping to do it with a toggle and not a rotary though. 

Ideally I'd like to use relays, but I don't know much about setting up a relay circuit. 
Is it possible to simultaneously switch two 4PDT relays from one toggle switch?
 

syn

Well-known member
Joined
Oct 10, 2005
Messages
623
Reaction score
3
regularjohn said:
Yeah, I was kinda hoping to do it with a toggle and not a rotary though. 

Ideally I'd like to use relays, but I don't know much about setting up a relay circuit. 
Is it possible to simultaneously switch two 4PDT relays from one toggle switch?
Yes, it is.
 

CJ

Well-known member
Joined
Jun 3, 2004
Messages
14,147
Reaction score
1,369
Location
California
easy with a switch, just do it,

look at hp oscillator, they do it,
 

regularjohn

Well-known member
Joined
Jan 23, 2009
Messages
321
Reaction score
2
Location
Raleigh, NC
CJ said:
easy with a switch, just do it,

look at hp oscillator, they do it,

Thanks CJ.
So should I worry about having the "out" side of both output paths permanently connected to the XLR jack?  ...since I'd only be switching the front side of the output path.
 

lassoharp

Well-known member
Joined
Jan 3, 2009
Messages
2,044
Reaction score
60
Location
USA
If it's possible - wire it so that the XLR out is the center or common - that way the XLR could only be connected to one path or the other at a time.  The output paths in this case would only be permanently connected to the switch throws.

Depending on the grounding requirements you may be able to do it with a DPDT.
 

regularjohn

Well-known member
Joined
Jan 23, 2009
Messages
321
Reaction score
2
Location
Raleigh, NC
I'm not quite sure what you mean there.

If I go from the pcb to the pole of the switch, then one throw would go transformerless out, and the other throw would go transformer out.  But they still have to go out through the same XLR jack.  What I'm worried about is unwanted impedance loading while in transformerless output because the secondary of the output transformer would still be sitting there on the output.

Or should I put the pole of the switch on the XLR jack, and then have each throw connected to the pcb?  So that there would be two outputs coming right off the pcb.  Would there be any issues doing it this way?
 

lassoharp

Well-known member
Joined
Jan 3, 2009
Messages
2,044
Reaction score
60
Location
USA
Sorry about the confusion there - a DPDT would not work for keeping all connections separate. Dunno what I was thinking.

You do need a 4PDT wired as:  poles 1 & 2 = PCB out,  hot, cold
                                       
                                          poles 3 & 4 = XLR,  hot, cold

                                          throw 1 (PC poles) =  transformer pri(s)

                                          throw 2 (PC poles) =  no iron

                                          throw 1 (XLR poles)  =  transformer sec(s)

                                          throw 2 (XLR poles) =  no iron


This gives you two separate output paths and avoids the situation of a constant parallel path you were referring to.
 

peat

Well-known member
Joined
Aug 31, 2009
Messages
100
Reaction score
0
I had a similar idea a while ago

check out this diagram (the transformer is wired incorrectly, but the signal flow is the same)

LL5402GSSLMOD.jpg
 

Latest posts

Top