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    Tube amp phase explanation

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    deepee99

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    Tube amp phase explanation

    Post by deepee99 on Sat Jun 24, 2017 9:56 am

    Let's start from scratch, might we? Perhaps I have mixed orangutans and oranges.
    "Phase" as applies to hi-fi has always meant to me that the drivers in a pair of speakers were firing in the same direction at the same time, in the same curve as it were.
    Am I now given to understand that speakers thus phased correctly differ in their presentation if together, while still being in phase relative to each other, that if the signal to both speaks is 180 degrees reversed, that a different presentation emanates?
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    PeppaPig

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    Re: Tube amp phase explanation

    Post by PeppaPig on Sat Jun 24, 2017 1:10 pm

    I agree. I'm not a physicist but have an understanding of physics relating to audio. I am just skeptical of claimes like this I have of course wiered speakers in all different ways and did not hear a diffreance except when one or othears were out of phase. I think this is diving into more sudo science then reallity. It could have more to do with psychological science then real science that can be proven.
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    Bob Latino
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    Re: Tube amp phase explanation

    Post by Bob Latino on Sat Jun 24, 2017 1:17 pm

    You can have two speakers that are "in phase" with each other or two speakers that are "out of phase" with each other. Two speakers in phase with each other may actually be out of phase with the recording. To complicate things further, every now and then a recording on vinyl or a CD because of the mixing etc. is out of phase with the original recording. If everything is "in phase" with your music system then the leading edge of all transient sounds are projected OUT towards you at the listening position a few feet away from the speaker. Whether you are aware of this or it makes any difference in the overall sound in your system is a subjective thing. Some may hear a difference and some may not ?

    Try this > disconnect your speaker wire at the amp and remove the grille cloth from your speaker. Now, get a 1.5 volt flashlight battery. Place the negative end of your speaker cable on the flat (negative end) of your 1.5 volt battery. Now place the positive end of your speaker cable on the dimpled (positive) end of the battery and hold it there for a couple of seconds. You will hear a "thump" and you will SEE THE woofer CONE MOVE OUT TOWARDS YOU. (positive phase). Now reverse the battery leads and notice that the woofer cone MOVES IN AND STAYS IN as long as you hold the two battery connections. Now in a simple situation like this you will hear the "thump" the same loudness and it will sound the same BUT when you have two speakers and a whole lot of music playing, there will be a subtle difference in the quality of sound coming at you ..

    Bob
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    PeppaPig

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    Re: Tube amp phase explanation

    Post by PeppaPig on Sat Jun 24, 2017 1:23 pm

    Rooms will affect phase of course less so for high frequency and more so for bass. You can of course measure with something like REW to find out. You can correct phase issue somewhat with a MINIDSP Many things mess with phase like defraction for example.
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    arledgsc

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    Re: Tube amp phase explanation

    Post by arledgsc on Sun Jun 25, 2017 11:06 am

    I agree with Bob.  He is talking about "absolute" audio phase of the entire audio chain including the recording studio, media, and reproduction by your audio system.  If a bass drum hit in a recording studio compresses the air and microphone you would want that recording playback to compress the air in your room at home.  If out of phase that same bass drum hit would decompress air in your room.  A lot of people can tell a difference in this effect.  Absolute phase is either in phase or 180 degrees out.

    Phase shifts caused by crossover networks, speakers, and even rooms are a whole different ball of wax.

    Dogstar

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    Re: Tube amp phase explanation

    Post by Dogstar on Sun Jun 25, 2017 11:48 am

    If our audio systems are set up correctly according to the component's setup instructions then there is really nothing we can do to correct for any of the manufacturing mistakes of the recordings that are made unless we are willing to adjust our cable and wiring configurations for every song on the CD or LP or audio files unless we have preamps that let us make the change at the flick of a switch.

    At least that's the way I'm interpreting what Bob just posted.
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    deepee99

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    Sorry I asked . . .

    Post by deepee99 on Sun Jun 25, 2017 12:04 pm

    So we're down to, if some schmuck engineer (please, no disparagement of engineers intended here) did an on-the-fly fix to a busted microphone cable down in the third row of the orchestra pit and inadvertently reversed that mike's leads, which results were missed at the mixing board, then your odds of achieving perfect phasing are worse than finding the black cat in the dark basement who isn't there...
    I wonder if prying my upright grand a few inches further from the wall, and angling it just a tad off the parallel, and raising a venetian blind at the far end of my music den, would raise the same kind of dissonance. Every now and then, even with the piano's dampers all unlifted, a string ot two will resonate to the stereo's output, thus altering the aural experience in my listening chair.
    It's all becoming clear to me, and now I understand some people's obsession with golf.
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    arledgsc

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    Re: Tube amp phase explanation

    Post by arledgsc on Sun Jun 25, 2017 12:15 pm

    deepee99 wrote:So we're down to, if some schmuck engineer (please, no disparagement of engineers intended here) did an on-the-fly fix to a busted microphone cable down in the third row of the orchestra pit and inadvertently reversed that mike's leads, which results were missed at the mixing board, then your odds of achieving perfect phasing are worse than finding the black cat in the dark basement who isn't there...

    You got it. I read somewhere of documented recordings where absolute phase was wrong. I even have a DAC that will reverse phase with a button press - both channels simultaneously. Same as connecting both speakers backward.
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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Sun Jun 25, 2017 12:33 pm

    arledgsc wrote:
    deepee99 wrote:So we're down to, if some schmuck engineer (please, no disparagement of engineers intended here) did an on-the-fly fix to a busted microphone cable down in the third row of the orchestra pit and inadvertently reversed that mike's leads, which results were missed at the mixing board, then your odds of achieving perfect phasing are worse than finding the black cat in the dark basement who isn't there...

    You got it.  I read somewhere of documented recordings where absolute phase was wrong.  I even have a DAC that will reverse phase with a button press - both channels simultaneously.  Same as connecting both speakers backward.

    My DAC has the same phase feature. I thought it rather Stone Age for such a spendy and elegant piece of gear but now I'm gettin' it, and it is recording-specific -- not just a matter of flipping speaker polarity. The effects are subtle, for sure, unlike the brute-force of reversing speaker leads on one side or the other.
    Maybe the old Heathkit guys had it right. I remember their pre-amps (Scott, Fisher & others had the same feature) had a selector that let you choose amongst straight two-channel, or mono-left or right to the whole system, and "stereo reverse." Of course, they also all came with about four different selectable EQ curves for the phono section, too, RIAA not being the standard back in dem days.
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    WntrMute2

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    Re: Tube amp phase explanation

    Post by WntrMute2 on Sun Jun 25, 2017 2:52 pm

    I have two things to contribute to this thread.  One is that Android phones users can make use of a polarity checker.  Is sends a known phase signal through your preamp and listens for the clicks.  It then "knows whether the click is positive or negative.  It is called, surprisingly enough--wait for it---Polarity Checker.
    Works as expected and is easy to interpret.  BTW, my Don Sachs built SP-14 inverts phase (the second thing) as does my Wright WLA-12a and my Cary SLP-98.


    Last edited by WntrMute2 on Sun Jun 25, 2017 4:43 pm; edited 1 time in total (Reason for editing : Added the word)
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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Sun Jun 25, 2017 2:55 pm

    WntrMute2 wrote:I have two things to contribute to this thread.  One is that Android phones can make use of a polarity checker.  Is sends a known phase signal through your preamp and listens for the clicks.  It then "knows whether the click is positive or negative.  It is called, surprisingly  enough--wait for it---Polarity Checker.
    Works as expected and is easy to interpret.  BTW, my Don Sachs built SP-14 inverts phase (the second thing) as does my Wright WLA-12a and my Cary SLP-98.  
    Well, maybe that polarity switch on the DAC will come in useful after all . . .
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    Tubes4ever

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    Re: Tube amp phase explanation

    Post by Tubes4ever on Sun Jun 25, 2017 4:07 pm

    Bob Latino wrote:[size=18][b]If everything is "in phase" with your music system then the leading edge of all transient sounds are projected OUT towards you at the listening position a few feet away from the speaker.

    This makes sense. For instance the sound of a baseball bat hitting the ball creates an initial pressure wave, not an initial decrease in pressure wave. Same with a crack of thunder or a drumstick hitting the drum head. The speakers need to move outward initially. I doubt it would make any difference on a violin solo, but any sound with abrupt transients would be affected.
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    PeppaPig

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    Re: Tube amp phase explanation

    Post by PeppaPig on Sun Jun 25, 2017 11:28 pm

    Tubes4ever wrote:
    Bob Latino wrote:[size=18][b]If everything is "in phase" with your music system then the leading edge of all transient sounds are projected OUT towards you at the listening position a few feet away from the speaker.

    This makes sense.  For instance the sound of a baseball bat hitting the ball creates an initial pressure wave, not an initial decrease in pressure wave.  Same with a crack of thunder or a drumstick hitting the drum head. The speakers need to move outward initially.  I doubt it would make any difference on a violin solo, but any sound with abrupt transients would be affected.

    I don't believe sound works that way but correct me if I'm wrong. With any sound there will be both positive and negative pressure at different frequency and it travels in a wave similar to a rock dropped in still water. I might add that there is no proof that are ears can tell between positive and negative pressure in regards to sound except when multiple frequency's overlap with different alignments. If you wire a speaker out of phase it will still produce positive pressure, it ill just be in a different timing of the frequency cycle in relation to in phase.

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    Peter W.

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    Re: Tube amp phase explanation

    Post by Peter W. on Mon Jun 26, 2017 7:57 am

    I kinda-sorta think that this is an interesting discussion. But we need to be very careful in separating the actual physics from speculation. Accordingly, I cobbled a bit of a reality test:

    One is in a live venue, and the proverbial cymbal crashes and very nearly (key word here when one is dealing in many hz) simultaneously, the drumstick strikes the snare drum.

    When the sound reaches you, who is to suggest that the wave-front reaches you ^ this way or / that way? Consider how far (vertically and horizontally, and offset) the snare drum is from the cymbal, how far either is from you, and whether the strikes on each was truly simultaneous or a few milliseconds apart.

    What strikes your ear is an amalgamation (also a key word, as compared to a mixture, meld, combination or alloy) of many sounds from many sources. There will also be, necessarily, interference waves, reinforcement waves and many other artifacts that may easily be described, but are tough to reproduce with any degree of accuracy. We strive to do so with a combination of machines none of which is perfect and many of which are seriously flawed. Such as requiring 226 square inches of rubber, paper and glue to reproduce the sounds of an organ Bombard pipe (area of two 12" conventional bass drivers).

    So: If the basic position taken is that a wave-front on the "push" is more 'natural' than one on the "pull", who is to suggest that each transient as-recorded (or as it hits the microphone) is vibrating the diaphragm one way or the other at that moment? Now, move on to the tympanum. Who is to suggest that what is going on in *your* ear is on the 'innie' or the 'outie'? Presumably, what is happening in your ear is a close analog of what is going on in the speaker... Or not? Now, consider that we have two (2) ears. They are about 5" - 6" apart, or so. Or, about half-a-wavelength at C5.

    Leading to microphone placement - surely they are some multiple/fraction of various waves apart from each other, and so will be recording variances by their nature. We think of sound as 'square waves' while (mostly) forgetting that square waves are composed of many sine waves each at its own frequency, each adding a subtle or not so subtle colorant to the tone

    Point being what hits the ear is a vast amalgam of 'ins' and 'outs' all at once. Even in a live venue. A recording/transcript (microphone-->electronics-->speaker will mix up that amalgam to some degree. We respond by using a traditional configuration multiple speakers to give us the best chance of capturing and repeating the original noise. There is nothing magical about it, nor is attempting to reason from the singular to the multiple useful as the target is constantly moving - and in no particular pattern. The best we can do is minimize any additional artifacts added (or actual artifacts deleted) by our noise reproducer system.

    Tom

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    Re: Tube amp phase explanation

    Post by Tom on Mon Jun 26, 2017 10:11 am

    FWIW - I think the battery for this phase adjusting thingy will also fit your old Makita drill...

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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Mon Jun 26, 2017 10:28 am

    I learned one thing from my days as a rock critic for the Seattle P-I. I and my compatriots were issued back-stage passes and pretty much had the run of the place, but instead of hob-nobbing with the band and drinking their beer, the best seat in the house was at the mixing board, usually about two-thirds of the way back on the main floor, or fairly close to the front rows on the balcony. Not sure what that had to do with phase, but at least you were sitting next to the guy whose ears were dictating the sound of the show.

    wildiowa

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    Re: Tube amp phase explanation

    Post by wildiowa on Mon Jun 26, 2017 10:44 am

    I will contribute what I can, again from working live shows etc. Seems there are two types of phase; first, observing the correct pos-neg orientation for speakers and amps, and then the inherent differences caused by the room and speaker position. The first is obviously a huge and fundamental issue, we understood hooking up speakers out of phase would literally cancel each other out..as Bob indicated, one pushes out, one pulls in...equals zero. Both pushing or pulling at the same time, same direction....that's good.

    As far as rooms and position, not much you can do there unless you are an obsessive. If you are wired correctly, but even one FOH speaker is a few feet in front of or in back of another, you have a phase issue. But is it noticeable? Probably not. We were even told that a horn not properly aligned with the woofer within the cabinet could cause a phase issue. But a live gig, who knows...who cares! There are even devices like the BBE Sonic Maximizer that I believe does something with the phase and EQ to adjust this effect.

    For hi-fi, in a room where things are stationary and don't move, I suppose you could mess with positioning and move stuff around until it sounds best to you. But the main thing is to have the correct pos-neg orientation all through your components including hookup, crossover, horns and woofer. Beyond that is really getting into the weeds and extremely hard to get absolutely scientifically right...but if it sounds good, that's the best test. As for that engineer who botched the wiring scheme for the Neumann mic back in 1958....well not much you can do at this point.
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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Mon Jun 26, 2017 11:19 am

    You're bringing back memories, wildiowa.
    When the big shows (Stones, Clapton, etc.) came to town, their sound company -- usually ShowCo out of Dallas -- arrived the day before the show and did a full day's work setting up the speaks and mikes, and if the band wasn't there yet, would have stand-in musicians to test the gear and speaker placement. It was quite the production.

    wildiowa

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    Re: Tube amp phase explanation

    Post by wildiowa on Mon Jun 26, 2017 11:48 am

    Yes, the old school, huge live shows...and as I discussed phase here, I thought how little the thousands of young kids totally zonked on various mind bending substances cared about the nuances of phase....they just cared about it being loud...LOUD...and recall when Keith Moon passed out on stage, fell off the drums, and they had to get on the mic and ask if anyone from the audience could play drums and come up and finish the show?? Those were the days! No one running the board had frequency analyzers feedback killers or phase adjusters....just crank it UP!!
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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Mon Jun 26, 2017 12:08 pm

    Boy, do we sound like a couple of old geezers.
    I remember when the Rolling Stones hired Ronnie Woods when Keith Richards was too zonked to play . . . they'd just un-plug Keith's lines and Ron would fill in with his own riffs. I don't know to this day if Keith knew what was going on . . .
    A concert, if it was going to be a component of a "live album" was always recorded at the mixer board, so the master tape was whatever the guy on the board was hearing. Talk about a one-armed juggling act. Those guys earned their pay.
    What most people didn't understand was that a "live" album was usually recorded at several different shows -- not just one concert. So the first track might have been done in San Francisco or Seattle or even Vancouver, the second in Milwaukee, etc., etc. Throw in a screaming applause over-dub and you can't tell where the venue changed.
    I did a series for the newspaper on what it was like to put on one of those huge shows, from the moment the Showco trucks showed up to the settling-up in a little room the night of the concert. The rule was, the settling-up occurred only after the lead band got all the way through their first tune. It was all done in cash -- even back in the 1970s several hundred thousand in $100 bills; no cheques or IOUs. Ticket-Master or whomever arrived in Brinks trucks with their suitcases. The band was paid, then the city, the venue, everybody getting their cut. Never before nor since have I ever seen such a pile of cash in one place.

    wildiowa

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    Re: Tube amp phase explanation

    Post by wildiowa on Mon Jun 26, 2017 1:12 pm

    Just a final thought on phase....with a single speaker, like a guitar amp with a single speaker or single cabinet, phase means nothing as I understand it...can be hooked up whatever whichever way, either polarity....it's cool. More than one, you got problems if multiple speakers are not in phase with the right polarity....this was something that drove me NUTS with something like the old Bose 800's where you had like eight, 2-ohm speakers wired together in some mystical crazy parallel/series dual flabbergaster pattern....you guys in Massachusetts....that was some weird stuff coming out of The Mountain or wherever it was.....still is with their line array concept.
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    Peter W.

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    Re: Tube amp phase explanation

    Post by Peter W. on Mon Jun 26, 2017 1:38 pm

    No highs? No lows?

    Must be Bose!
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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Mon Jun 26, 2017 1:39 pm

    Serious thread drift here, but yeah, I never got the Bose concept. When the 901s came out, properly set up in our neighbourhood dealer's show-room, everybody lined up to hear this fantastic new sound, the audiophiles gushing appropriately.
    I thought they stunk and loudly said so. Needless to say, I was not invited back to the dealer's next audition ceremony.
    Back to phasing. I took the top cabinet pieces off my old upright piano over the weekend for its annual vacuuming. Talk about angles, bends, wood resonance, sound-board, the hammer and damper array, etc., etc., etc. It's not as much fun to play it now, knowing there's no phase-perfection possible. Maybe if I swapped out the old brass bolts with some new chrome-moly fasteners ...


    Last edited by deepee99 on Mon Jun 26, 2017 1:59 pm; edited 1 time in total

    wildiowa

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    Re: Tube amp phase explanation

    Post by wildiowa on Mon Jun 26, 2017 1:53 pm

    Yes I've done my bit to derail the original post, and I hope Bob will let me perhaps open a separate dedicated discussion thread of Bose here in the future....even if it is not Dyna-related maybe he will allow it since they are in his home base of MA and seem to thrive on unconventional, controversial design and products. I have much-o experience with Bose, mostly live stage acts....and opinion, and would also like to hear what you guys think. Now it's the line array systems that are all the rage. Although this site is the greatest Dyna resource, ever, there is so much knowledge, experience and background on so many related topics things seem to morph and evolve. OK...we are returning control of this thread back to you.....
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    deepee99

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    Re: Tube amp phase explanation

    Post by deepee99 on Mon Jun 26, 2017 2:43 pm

    wildiowa wrote:Yes I've done my bit to derail the original post, and I hope Bob will let me perhaps open a separate dedicated discussion thread of Bose here in the future....even if it is not Dyna-related maybe he will allow it since they are in his home base of MA and seem to thrive on unconventional, controversial design and products. I have much-o experience with Bose, mostly live stage acts....and opinion, and would also like to hear what you guys think. Now it's the line array systems that are all the rage. Although this site is the greatest Dyna resource, ever, there is so much knowledge, experience and background on so many related topics things seem to morph and evolve. OK...we are returning control of this thread back to you.....

    We need someone with a polyphasic personality to push this doomed puppy right off the edge Smile

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