The Amp Garage

Bombacaototal wrote: ↑Fri Jan 17, 2020 10:01 pm How would you wire it to the amp?

The same way as in the diagram you posted above, only the phase switch is fed from the Impedance switch (or whatever impedance is used if the transformer only has one output). Like this:

Thank you very much Dave!

Colossal wrote: ↑Fri Jan 17, 2020 6:24 pm

Bombacaototal wrote: ↑Fri Jan 17, 2020 4:35 pm

Colossal wrote: ↑Fri Jan 17, 2020 4:17 pm I use a phase reversal switch on my cabs and/or amps

Like this? Where do you usually install the switch? on the back of the cab next to the input jack?

Hi Raphael,

Yes, that is how I wire the switch. On cabinets, yes, I install the switch next to the input jack. It works great and if you get the phase match wrong, just click the switch. The sonic difference between an amp that is in and out of phase with its speaker is VERY obvious.

Paul and Pete, I am referring to the relationship between an amp and the cabinet it is attached to. If you miswire a multi-speaker cab, that is a separate problem.

FWIW, note that Matchless includes(ed) a phase reversal switch on their amps. I've been doing this for years.

Best,
Dave

Dave ,

if you put the switch on the cab, does that make the speaker plug sleeve hot when it's flipped? i.e can you get a shock if you touched it, or damage the amp if it shorts?


M

Just did the A/B test on a 1x12 with EVM 12S and my SSS 004. It is indeed very noticeable and indeed the Two Rock reverse option works better for this amp. Makes the amp is less muffed, more open and brighter

Bombacaototal wrote: ↑Sat Jan 18, 2020 11:40 am Just did the A/B test on a 1x12 with EVM 12S and my SSS 004. It is indeed very noticeable and indeed the Two Rock reverse option works better for this amp. Makes the amp is less muffed, more open and brighter

how did you swap it?


M

If its 1x12 just swap the leads going to + and - on the speaker

If it is a 2x12 then swap the leads going to the tip and sleeve on the jack

norburybrook wrote: ↑Sat Jan 18, 2020 9:50 am Dave ,

if you put the switch on the cab, does that make the speaker plug sleeve hot when it's flipped? i.e can you get a shock if you touched it, or damage the amp if it shorts?

Hello Marcus,

On a speaker cab, I use an enamel coated jack plate and shoulder washers on a Switchcraft jack to keep everything isolated. If the phase switch shorts, then yes, the amp would be running into a full short. As Geeze/Russ would say, there would be a great uttering of power words.

absolute phase only really matters when you are running multiple amp/cabinets at the same time. any of the rest of this "being able to hear a difference between half cycles of a sine wave" is utter nonsense
I'm not saying the fella up there didn't hear anything due to confirmation bias but that's about it

thetragichero wrote: ↑Sat Jan 18, 2020 10:16 pm absolute phase only really matters when you are running multiple amp/cabinets at the same time. any of the rest of this "being able to hear a difference between half cycles of a sine wave" is utter nonsense
I'm not saying the fella up there didn't hear anything due to confirmation bias but that's about it

Well shit dude, thanks for setting us all straight on what we hear and don't hear....if you can't hear a difference, then there must not be one.

I'm sure Ken Fischer and Howard Dumble wired their speaker cables in reverse because they were idiots laboring under the delusion of confirmation bias and it made no difference

Well, I think I have pretty good ears. And I cannot tell the difference in polarity when there's a single speaker. So there's one more thing I don't have to worry about!

yo dawg, the math doesn't add up. what's the lowest note on your guitar? 82hz is what my chart says. so 164 half cycles per SECOND. I'll let you do the googling but that difference is well beyond HUMAN perception
I'm not a guy to deify some dudes just because some famous guys played their amps. especially quirky, eccentric types. when I've been questioned about my own odd behavior, i have been known to find any justification whatsoever for it. don't see where these fellas would be any different
if the math don't add up, i always call BS
guitar gear ain't sorcery. it's all rather simple

thetragichero wrote: ↑Sun Jan 19, 2020 2:40 am yo dawg, the math doesn't add up. what's the lowest note on your guitar? 82hz is what my chart says. so 164 half cycles per SECOND. I'll let you do the googling but that difference is well beyond HUMAN perception
I'm not a guy to deify some dudes just because some famous guys played their amps. especially quirky, eccentric types. when I've been questioned about my own odd behavior, i have been known to find any justification whatsoever for it. don't see where these fellas would be any different
if the math don't add up, i always call BS
guitar gear ain't sorcery. it's all rather simple

And that's perfectly fine. I am absolutely not questioning the math. I knew contributing to this thread would spark controversy, but I wanted to help Raphael out. I couldn't give a squirt of piss if anyone thinks I'm full of shit or not, I simply don't care. I am not out to convince anyone of anything. Try it and see, or don't. If you hear a difference for better or worse, then it was worth your time. But if not, then as Xtian said...one less thing to worry about.

I only brought up Dumble and Fischer as examples where this has been done by well known builders.

The way I found about this was from building an Express many years ago and was quite surprised after I added and then flipped that phase switch, because a sine wave is a sine wave, right? Since then, I keep a phase switch on my cabs. I have a detuned 4x12 with a pair of Greenbacks in two of the holes and the other two empty. When run with my favorite 2xEL84 amp out of phase, the sound is rather harsh and flat and kind of "mono" sounding. Flip that switch and ah, there it is, it gets wide and airy. Another example is when I recently switched said 2xEL84 amp from individual screen resistors to a single shared resistor. Had to flip the switch after that change. Again, quite surprised. I have not tried this with every amp so can't infer what it might or might not do in every situation.

Like I said though, I've got no dog in the fight. Did you read the link I posted to the Trainwreck discussion talking about this?

I appreciate the contribution Dave, and to my ears the difference was not subtle, it was night and day on my SSS 004. So I am happy I did it....I think how HAD mixed dry and wet reversed the polarity in the amp, as this is not applicable to other of his designs?!

If others cannot hear, well, like Xtian said, one less thing to worry about...

I just hope that the contributors have at least made a test, before jumping into one side or the other

In a complex system, one person's experience in a specific case does not often produce a universal truth.

Quoting Glenn (Geetarpicker) in the thread linked above by Dave:

"...in my experience the phase of the sound coming out of the speaker cabinet can effect the sustain but it's note dependent. Of course even guitar body position is important to explore as it also effects the phase of the sound physically hitting the guitar. Point is having the phase one way can make controlled feedback great on certain notes, and dead on others. Then you flip the phase and the notes that are favored/cancelled totally change. In the studio I regularly employ a speaker cord that is wired with opposite phase. Then if I'm having an issue getting sustain on a certain note on a solo I'll swap the speaker cable, effectively swapping the phase and most of the time helping any sustain issues."

The room, guitar, amp, FX, cabinet, and the player and amp positions in the room all have a role. In the case of the low E, half a wavelength (the difference between negative and positive feedback from the speaker to the guitar) is about seven feet. For the 12th fret on the high E string, it's about one foot. It's easy to see that in a lively room, there will be a great many different phase relationships present. Some people have suggested that the motion of the speaker cone on the initial attack is important, but I'm inclined to believe that the speaker-guitar feedback is the most noticeable factor.

Glenn also cautions about the shock and shorting hazard of using reversing speaker cables, and that also applies to phase reversing switches that are installed in the amp, which will make the speaker cable plug shells hot with respect to ground. !00W into 8Ω is about 40V peak. The safest arrangement is to put the phase reversing switch in the speaker cab, where it is only reversing the polarity of the connections to the voice coils. I can imagine a small portable box with a jack on one end, a switch (a rocker type seems like a good option), and a plug on the other end that could be used for this purpose. That would provide almost the same safety isolation, but some added risk of an open secondary.

OK, wait. Consider phase vs polarity. In the above example, talking about the physical length of sound waves, a PHASE switch would be helpful. I have such a switch on my subwoofer for my studio monitors. But for guitar cabs, we're talking about a POLARITY switch, which will not affect the physical position of nodes and antinodes in a room.