how to reverse signal for Common Cathode circuit

[sam8888ysl]

I had found many DIYER's preamp use only one tridoe.
the output singnal of Common Cathode is reverse
and how to deal with this problem

I change the speaker's connect +-
and its works

[ray_moth]

It's true that a single common cathode stage causes 180 degrees phase shift of the signal, but why do see that as a problem?

[sam8888ysl]

but its sounds a little different

[Robert McLean]

but its sounds a little different

Well, you have already stated the answer in your original post, simply reverse the speaker connections.

[kevinkr]

Sam, you're talking about absolute polarity and on some material the effect is very audible, depending quite a lot on speaker design. Some percussion and choral works highlight this effect pretty strongly. For the last 20yrs I have included facilities for selecting the output phase in most of my line pre-amplifier designs.

These days I use transformer coupled line stages so phase selection can be easily achieved with a single dpdt switch in the output. My older designs used variations on LTP topology to accomplish the same thing.

Most of the time I am a casual listener and find arbitrary phase acceptable on most material - once in a while I while discover something that just sounds wrong.

The effect is not audible on a lot of material, particularly non-acoustic music..

I found the speaker lead swapping routine annoying when I was much younger, which drove the design approach I currently use.

Whether or not this is controversial in some circles I spent a lot of time when I had the time for these things investigating the issue. Even going as far as to do blind testing to determine whether a captive audience could identify the effect, and those who were sensitive to the effect seemed in many cases to get things right about 80% or more of the time. I used popless switching, levels matched to better than 0.1dB phase to phase, arbitrary phase with switch /no switch scenarios. It was a bit complicated.. I ran about 7 people through the process, IIRC only 1 could hear no difference, and 1 was 100% correct in repeated trials. I was relatively convinced at the time that no one was keying on anything else I was doing, but you never know, and I investigated no further.

[tubelab.com]

When my daughter was in high school I did a lot of recording of her (drums) and her friends playing musical instruments using a computer based recording system. My monitor speakers were the same Yamaha NS-10M's that I use now. The amplifiers were SS then though. I found that the persussive sounds sounded more realistic when the cone moved outward when the drum head was hit. Think of this as absolute phase from the original source to the speaker cone.

Was this observation due to speaker nonlinearities, or psychoacoustics, since I knew that the bass drum head moved toward me when she stomped the pedal? I don't know. Phase was flipped by swapping the speaker leads.

[sam8888ysl]

Originally posted by kevinkr

use transformer coupled line stages

seems a good idea
but I like cap coupling
a little bit cheaper and easy

i had tried just reverse the output connection of RCA
but hums ......
well, I seperate the output and circuit with two CAPs and one resistor.
still hums.....

[planet10]

Given that there is no standard for abs phase when recording and that in those recordings well enuff done for abs phase to make a difference, probably 1/2 go one way, and the half go the other way, worrying about whether a device reverses phase seems silly -- you need to have a switch so you can change abs phase record to record (or even song to song)

dave

[sam8888ysl]

Originally posted by planet10
you need to have a switch so you can change abs phase record to record (or even song to song)

dave

hi dave
nice to hear u
u mean just only a switch to change the connection before output
but why i change them dirrectly and hums.....
due to i did not use coaxial cable for
i use 1mm OCC stand wire

[Brian Beck]

Originally posted by planet10
Given that there is no standard for abs phase when recording and that in those recordings well enuff done for abs phase to make a difference, probably 1/2 go one way, and the half go the other way

With most modern multi-track recordings absolute polarities are mixed among the many tracks anyway, even within the multi-miking of one drum kit. So the resultant mixed recording has no reference phase. For an electric guitar played through effects, how would one define correct absolute phase anyway? Nevertheless, with some multi-track recordings flipping phase DOES makes a difference, to me and to many of my audiophile friends. I suspect we're often keying on the big wavefront of the kick drum and maybe the toms, as Tubelab suggests. Sometimes one way sounds better, sometimes flipping phase just sounds different, not necessarily better or worse. Sometimes (often) there seems to be little difference at all.

But then there are some minimally-miked orchestral and small ensemble recordings that do seem to preserve a consistent phase, but it can be inverted or non-inverted, so a phase reversal switch can be useful. I have one Nonesuch LP of a percussion music ensemble that sounds dramatically better in one position than the other.

Originally posted by planet10
...worrying about whether a device reverses phase seems silly

Some listeners find that setting the signal polarity for recordings is useful. I wouldn't call that "silly". I suppose you mean that it doesn't much matter if any one component reverses phase because in the end you will have to try both total-system phase settings for each recording. For most of my listening, I just leave my system set to non-inverting polarity and I don't worry about it much.