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    VTA ST-120 phase?

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    Rich

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    VTA ST-120 phase?

    Post by Rich on Fri Nov 07, 2014 9:13 pm

    The preamp I'm using now with my st120 inverts phase at the output.
    At the owners manual, it say to invert speakers polarity.
    I doubt this is not applicable to St120 because of the preamp low gain card.
    Am I right?

    Best regards.
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    sKiZo

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    Re: VTA ST-120 phase?

    Post by sKiZo on Sat Nov 08, 2014 12:28 am

    Easiest way to check ... switch the +/- leads and see which setup gives you the best bass.

    Does sound a tad strange though ... what pre, and could you post up the exact text from the manual telling you to do this?

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    Rich

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    Re: VTA ST-120 phase?

    Post by Rich on Sat Nov 08, 2014 12:56 am

    Hello,
    The pre is a Cary SLP98.
    The manual text: " Amplifier – Speaker Connection • The SLP 98 (line and phono) preamplifier is phase inverting. • This will require you to connect the positive speaker terminal to the negative binding post on your amplifier. The negative speaker terminal will connect to the positive binding post on your amplifier. "

    Already did this way.
    Awfull sound...!!!
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    PeterCapo

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    Re: VTA ST-120 phase?

    Post by PeterCapo on Sat Nov 08, 2014 9:43 am

    Yes, the SLP-98 has inverted phase at its output, and the solution is to simply reverse the connections either at the speakers or the power amp outputs (not both).  I believe there are some other preamps on the market that do this, as well.  In and of itself, it should not be the source of "awful sound" - I'd look elsewhere for the cause, if something sounds that bad.

    Rich, can you clarify your meaning when you wrote in your original post: "I doubt this is not applicable to St120 because of the preamp low gain card."

    Thanks.
    Peter
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    Rich

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    Re: VTA ST-120 phase?

    Post by Rich on Sat Nov 08, 2014 10:16 am

    Hello Peter,
    I read that two of the three drivers tubes are phase inverters.

    Best regards
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    Bob Latino
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    Re: VTA ST-120 phase?

    Post by Bob Latino on Sat Nov 08, 2014 10:25 am

    The VTA ST-120 does NOT invert phase. Neither does the VTA ST-70 or the VTA M-125 monoblocks. If your preamp does invert phase then the audio signal (out of phase) will be sent to your VTA amp. The out of phase signal will then be sent to your speaker outputs. As has been said above, all you have to do is reverse the two positive and negative wires on your speaker and your system will be in phase.

    I had a customer (John Inlow of Inlow Sound in Portland, OR) who made a custom speaker installation using two M-125's to drive two bass horns in a multiamp setup with crossovers. When he first ran the system, it didn't sound right. It turns out that the midrange amp had reverse phase and the M-125's do not. Reversing the speaker wires to the M-125's straightened out the issue. Go to John's web site below and click on "125 watt KT88 tube amplifier" on the left side of the page. It explains in more detail about John's issue with his multi amp setup.

    Inlow Sound

    Bob
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    Rich

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    Re: VTA ST-120 phase?

    Post by Rich on Sat Nov 08, 2014 11:01 am

    Thank you Bob!

    Best regards.
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    tubes4hifi
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    Re: VTA ST-120 phase?

    Post by tubes4hifi on Mon Nov 10, 2014 1:21 pm

    quite a few preamps invert phase so not surprising that the Cary is one of them

    zx

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    Re: VTA ST-120 phase?

    Post by zx on Tue Nov 11, 2014 10:36 am

    Conrad-johnson ,Cary an othes invert phase at the outputs of there preamps Because......Thay would have too add one more stage....one more tube for the output to go though just to put the output back in phase....
    So you got to run wire to the speaker anyway an the speaker dose not mind if your Reversing the input..in this case.....have fun with tubes............ in 2014 .....gofig




    Thanks for the site Bob.....................
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    Rich

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    Re: VTA ST-120 phase?

    Post by Rich on Tue Nov 11, 2014 10:57 am

    Thanks for your input.
    I've already reversed my speakers connections.
    It sounds amazing.


    Best regards.
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    jfine

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    Re: VTA ST-120 phase?

    Post by jfine on Wed Jun 21, 2017 12:30 pm

    Bob Latino wrote:The VTA ST-120 does NOT invert phase. Neither does the VTA ST-70 or the VTA M-125 monoblocks. If your preamp does invert phase then the audio signal (out of phase) will be sent to your VTA amp. The out of phase signal will then be sent to your speaker outputs. As has been said above, all you have to do is reverse the two positive and negative wires on your speaker and your system will be in phase.

    Bob

    Bumping this thread as this is *very* audible in my system, seems many preamps (especially tube ones), invert phase, changing absolute polarity. And apparently, amps may do this as well. I had to "play it by ear". Some may not hear this effect at all.


    Dogstar

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    Re: VTA ST-120 phase?

    Post by Dogstar on Wed Jun 21, 2017 9:25 pm

    So are you saying the sound you experience from an inverted phase preamp is similar to when you accidentally connect one speaker correctly and the other one incorrectly?
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    deepee99

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    Re: VTA ST-120 phase?

    Post by deepee99 on Wed Jun 21, 2017 10:05 pm

    An easier way to check phase than merely guessing at the bass is, if you can, set your speakers up a foot apart facing each other. You'll know for sure if one is nulling the other, in which case you're definitely out of phase.
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    jfine

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    Re: VTA ST-120 phase?

    Post by jfine on Wed Jun 21, 2017 11:06 pm

    Dogstar wrote:So are you saying the sound you experience from an inverted phase preamp is similar to when you accidentally connect one speaker correctly and the other one incorrectly?

    No, that I believe is an out of phase issue, when one side is reversed. That sounds awful. Absolute polarity is both sides reversed/inverted.

    something to read (add http, wont let me cause I'm too new here)

    forums.stevehoffman.tv/threads/reversing-red-black-speaker-wires-polarity-vs-phase.1992/

    .


    Last edited by jfine on Thu Jun 22, 2017 12:58 am; edited 1 time in total
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    jfine

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    Re: VTA ST-120 phase?

    Post by jfine on Wed Jun 21, 2017 11:09 pm

    deepee99 wrote:An easier way to check phase than merely guessing at the bass is, if you can, set your speakers up a foot apart facing each other. You'll know for sure if one is nulling the other, in which case you're definitely out of phase.

    Yes another way to do it if you can't hear it. I have a smaller room, currently running JBL L150's, modded xovers. I hear it no problem.
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    pichacker

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    Re: VTA ST-120 phase?

    Post by pichacker on Thu Jun 22, 2017 2:08 am

    If you are using only one pair of speakers and one amplifier then you would not hear any difference if BOTH channels are inverted compared to non inverted. After all, can you be 100% sure that the signal from your source is not inverted in the signal processing path? After all which way is up really?

    You will of course hear if a single channel is inverted as there will be a cancelling effect as the speakers work against each other. This usually presents itself as a hollowness in the bass and a loss of image.

    As Bob says, if you are working with multiple amplifiers then getting the phase correct is important for all speakers.
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    jfine

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    Re: VTA ST-120 phase?

    Post by jfine on Thu Jun 22, 2017 1:24 pm

    pichacker wrote:If you are using only one pair of speakers and one amplifier then you would not hear any difference if BOTH channels are inverted compared to non inverted.

    I hear it. It is unmistakable in my system. Either with 2 monoblocks or 1 stereo amp.
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    Peter W.

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    Re: VTA ST-120 phase?

    Post by Peter W. on Thu Jun 22, 2017 4:48 pm

    Basics of hooking up speakers:

    a) As long as each speaker is hooked up in the same way, it makes no difference. Whether Red-to-Red/Black-to-Black, or Black-to-Red/Red-to-Black. It is important that speakers be 'in phase' with each other. No more.

    b) Unless one is using two different amplifiers with different characteristics, or two different pre-amps with different characteristics, this will remain the case, full stop.

    c) Outlyers: There are several. One example - does anyone here remember the Advent 500 Sound-Space Control? This did invert the outputs and the 'second' manual corrected the first in advising the user to connect the rear speakers the opposite of the front speakers. Some equalizers do this as well. But this is really applicable only to multiple-speaker (more-than-two) applications.
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    jfine

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    Re: VTA ST-120 phase?

    Post by jfine on Thu Jun 22, 2017 7:32 pm

    Peter W. wrote:As long as each speaker is hooked up in the same way, it makes no difference. Whether Red-to-Red/Black-to-Black, or Black-to-Red/Red-to-Black. It is important that speakers be 'in phase' with each other. No more.

    Wrong, else why would I hear a difference if BOTH sides are wired inversely?

    I would say that if you cannot hear the difference and sounds good to you, that's all that matters.

    A little googling on Absolute Polarity as it pertains to audio signals would help, I would post links but I'm too new Rolling Eyes

    .
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    Peter W.

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    Re: VTA ST-120 phase?

    Post by Peter W. on Thu Jun 22, 2017 8:13 pm

    Wrong, else why would I hear a difference if BOTH sides are wired inversely?

    Expectations would cover that. Not to be snarky, "google" basic physics.....
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    Bob Latino
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    Re: VTA ST-120 phase?

    Post by Bob Latino on Thu Jun 22, 2017 8:26 pm

    I am with jfine on this one. In one system that I have downstairs I have a BAT VK30SE preamp. On the remote with this preamp there is a phase button. You can alternate the phase of the preamp by just pressing the button. On the preamp itself an led comes on when the amp is in positive phase. Running two M-125's on this system (which do have positive phase), the positive phase on the preamp does give a little more bass and a more natural overall sound. You can hear the subtle difference between the positive and negative phase as you alternate presses of the phase button.

    Bob

    Dogstar

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    Re: VTA ST-120 phase?

    Post by Dogstar on Thu Jun 22, 2017 8:27 pm

    The point being that one speaker would need to be wired inversely relative to the other in order for the speakers to be connected out of phase to each other.

    My original question was to clarify how the system would sound.

    I have a Cary SP-100 SS preamp that cannot be setup inversely phased as the OP can with the Cary preamp he has.
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    deepee99

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    Re: VTA ST-120 phase?

    Post by deepee99 on Thu Jun 22, 2017 8:32 pm

    jfine wrote:
    Peter W. wrote:As long as each speaker is hooked up in the same way, it makes no difference. Whether Red-to-Red/Black-to-Black, or Black-to-Red/Red-to-Black. It is important that speakers be 'in phase' with each other. No more.

    Wrong, else why would I hear a difference if BOTH sides are wired inversely?

    I would say that if you cannot hear the difference and sounds good to you, that's all that matters.

    A little googling on Absolute Polarity as it pertains to audio signals would help, I would post links but I'm too new Rolling Eyes

    .

    Yeah, what Peter W. said -- all of it. Speakers don't know + from - or red from black, per se. It's that they're firing in phase that counts. Whether that's both red wires to both black connectors and both black wires to both red posts, it does not matter. The point is that they're supposed to be firing in the same direction at the same time.
    I suppose phasing could get dicey if internally some doof at the factory wired the woofs to the mids/highs out-of-phase but that's not something you can fix from the outside.
    This all assUmes that your speakers are more or less shooting straight forward. It would be interesting to know what effect phasing has on toed-in or -out arrangements, if any.
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    Kentley

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    Re: VTA ST-120 phase?

    Post by Kentley on Thu Jun 22, 2017 8:51 pm

    "This all assUmes that your speakers are more or less shooting straight forward. It would be interesting to know what effect phasing has on toed-in or -out arrangements, if any." -- deepee99

    Phase irregularities are ALWAYS a factor in speaker placement and room treatment. The ways two (or more) speakers interact with each other and with the room have a huge influence on sound. And, of course, this changes drastically at different frequencies.
    One of the tricks I have discovered in set-up is to initially use a well-known good mono recording. This can tell your ears more about phase relationships because technically the sound is identical in both (or all) speakers. If the sound apparently comes from dead center, and all frequencies are smoothly represented you are on the right track, and then you can move to stereo images. In fact, before even a dual-mono signal you should check each speaker separately with its own mono signal. Each should sound natural and balanced from the listening position. And don't forget that finding the optimal listening position is crucial, too. In my own relatively shallow room, moving the listening chair forward or backward an inch or two gives a drastically different soundscape. Thank {insert deity} that I truly enjoy this on-going activity. Sometimes I actually stop for a month or so and Enjoy the Music! bounce

    Oh, and there are some astute ears which have actually proven themselves to hear the differences of "absolute phase" . But it's very rare. I believe that the inscrutable human brain is capable of both recognising, and compensating for, the "push vs. pull" of auditory phase.


    Last edited by Kentley on Thu Jun 22, 2017 8:58 pm; edited 1 time in total
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    jfine

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    Re: VTA ST-120 phase?

    Post by jfine on Thu Jun 22, 2017 8:55 pm

    Peter W. wrote:Expectations would cover that. Not to be snarky, "google" basic physics.....

    Not sure what you mean by expectations.

    How about this,

    Instead of stating as fact, "As long as each speaker is hooked up in the same way, it makes no difference."

    just add to the end

    "...on my system, with my ears, in my room"

    Since we all experience differently, it's impossible that what you state is true.

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