Moderators: pompeiisneaks, Colossal
Does that amp have a negative feedack loop in the power section? If so, I would think the switching would be pretty complex. If not, then piece of cake.JimiB wrote:Matchless did this in the DC-30 with isolated speaker jacks and a heavy switch. works like a charm. On the cab though you wouldnt need to isolate the jacks.
Isnt reversing the OT sec. the same as wiring the speaker cable reversed?ayan wrote: Totally agree with the math and the concept. I, unfortunately, also hear a difference with the OT secondary polarity reversed. However, one thing that is also a huge variable is where you play the amp. I have played the same amp/cab in a carpeted studio and have to struggle to get the thing to feedback for me; on the other hand, I have done gigs with glass or mirrors behind the stage and then my struggle is aimed to control my 335 from taking off all by itself.
True- The pickups could change the phase just like the loop or spkr cable does. So you might get this all working great for one guitar and the next one requires a phase change. And if Scott has observed this than I am more inclined than ever to put a phase switch on my cab, if not in the next amp I build. You could do it on the guitar too (easier if the shields do not also carry signal - A bit togher for vintage pups).ayan wrote: One thing that completely makes the theory fall apart, IMHO, is: how do we know that, as we strike a note on the guitar, the signal will have a positive peak insted of a negative one? Not all pickups are consistent from one to the next -- for example, it is a well-known fact that Fralin flips the magnet on all his humbuckers so they end up being out of phase with Duncans, Gibsons, DiMarzios, etc. So which type take off upward and not downward at signal rise? Let's not even discuss the deliberate wiring of two humbuckers out of phase with one another...
Gil
Well, not really. You do achieve the same effect as far as the signal phase goes. But flipping the OT connections to the speaker jack in the amp that has a negative feedback loop will turn the loop will turn into a positive feedback one, unless you also reverse the PI plate connections to the power tubes.Tonegeek wrote: Isnt reversing the OT sec. the same as wiring the speaker cable reversed?
I forgot about the NFBayan wrote:Well, not really. You do achieve the same effect as far as the signal phase goes. But flipping the OT connections to the speaker jack in the amp that has a negative feedback loop will turn the loop will turn into a positive feedback one, unless you also reverse the PI plate connections to the power tubes.Tonegeek wrote: Isnt reversing the OT sec. the same as wiring the speaker cable reversed?
If you flip the speaker wire (i.e., outside of the amp) polarity, you will not be changing the phase of the signal inside the amp and therefore not making a positive loop around the power section.
Cheers,
Gil
I already found out the hard way what pos. feedback does That gives me an idea though. You could rig a switch on your amp for those nights when the drunks just won't go home at closing time. Hit the switch and put pos. feedback on the PI till they leave. Makes a good fire alarm too...Cool, thanks dogears. I can hang my hat on that.the current thinking is that the OD tone has a very assymmetrical waveform.
No, it would go out the front and back, like any other input.Stanz wrote:Cool, thanks dogears. I can hang my hat on that.the current thinking is that the OD tone has a very assymmetrical waveform.
In thinking about it, I seem to recall that the OD signal has a small peak in it on one side, small peak translating to higher freq. A speaker with reversed phase would be sending these freqs to the back of the cabinet.
