Read your manual!!!!!!!!!!!

[187CAM]

After many years of owning what I'd like to consider some of the upper end of the audio spectrum of gear I've come to find one thing that has been overlooked and costly to my ears. I really enjoy my Conrad-Johnson PV-12L pre-amp. This has been without a doubt one of my first choices in a pre-amps. I liked the soundstage, presence and neutral playback of this pre-amp. BUT, today I found something I have been missing for years now. This pre-amp is phase inverting.

I decided for some reason to collect all the manuals for the gear I am using at the moment and take this into the 'library' (reading room / bathroom) and have a session of higher learning about what it is I am listening to. This is when I found the note / article on page 8 titled "Absolute Phase". I learned that this pre-amp is phase inverted. A simple solution is to switch the wires at either the amp or speaker from (+ to +) to (+ to -). Or connect the positive terminal of the speaker cable to the negetive post of the speaker and likewise for the negetive cable connection to the positive post of the speaker.

All hell has broken loose. I've gone from what I thought was a really good sounding system to what I now consider (IMO) to be a fantastic sounding system. I can now hear subtle differences in the recordings I have never heard before on this system. I am amazed at the difference. I'm using a Conrad-Johnson MV125 behind this PV-12 so I called CJ to see if the phase inversion was a needed policy to follow. I was instructed that it was indeed. I feel so stupid for the act of #1. NOT reading the manual for all these years and #2. telling you guys about my mistake.

Take what you want from this but remember one thing. No matter how long you've been in this addiction you may not know all the rules of audio engagement. READ THE MANUAL. I've actually found new music now.

That is all.

[ben62670]

My buddy and I were just discussing this. Too bad speaker cable swapping doesn't work with SDA's. I also have flipped the cables on my tweeters with good results(a little off topic).
Ben

[WilliamM2]

I am amazed at the difference. I'm using a Conrad-Johnson MV125 behind this PV-12 so I called CJ to see if the phase inversion was a needed policy to follow. I was instructed that it was indeed. I feel so stupid for the act of #1. NOT reading the manual for all these years and #2. telling you guys about my mistake.


I don't know why you would feel stupid. Seems more like a stupid design to me. I mean, if reversing the wires on the amp is required as they told you, why did they invert them on the pre in the first place?

[dkg999]

I have a Rogue pre that is also phase inverting, and in experimenting with my Magnepan 1.6's it indeed does make a difference which way you have the speaker cables connected.

[187CAM]

I have a Rogue pre that is also phase inverting, and in experimenting with my Magnepan 1.6's it indeed does make a difference which way you have the speaker cables connected.

What a difference it makes.

[Kenneth Swauger]

Hello,
For owners of SDA speakers, who listen to vinyl, and have an inverting pre-amp and a non-inverting power amp and want to experiment, try this:
1). go to the tonearm wires that connect to the cartridge.
2). swap the red and green wires, connect the red arm wire to the green terminal on the cartridge. The green tonearm wire to the red terminal.
3). do the same on the left connections, blue goes to white, on cartridge, and white tone arm wire to blue cartridge terminal.
A phono cartridge is a balanced device allowing you to reverse the absolute polarity of the signal leaving the cartridge. This would not apply to owner's of older Decca cartridges.
Regards, Ken

[steveinaz]

All hell has broken loose. I've gone from what I thought was a really good sounding system to what I now consider (IMO) to be a fantastic sounding system.

The good side; it's like buying it new all over again! Enjoy.

VERY TRUE stuff though. There's more than a few preamps that invert the output, and you will definitely notice a difference when you switch your speaker wires the way they recommend.

[Flash21]

All hell has broken loose
But in a good way. :)

All this is yet another reason I luv integrated amps.

[zingo]

I didn't even realize electronic equipment came with manuals; good to know. :p

[Face]

Thanks Ken!

[mhardy6647]

This is when I found the note / article on page 8 titled "Absolute Phase". I learned that this pre-amp is phase inverted. A simple solution is to switch the wires at either the amp or speaker from (+ to +) to (+ to -). Or connect the positive terminal of the speaker cable to the negetive post of the speaker and likewise for the negetive cable connection to the positive post of the speaker.

Just out of academic curiosity: do you know whether other components in your system (source, amplifier) invert or maintain phase?


I didn't even realize electronic equipment came with manuals; good to know. :p
You need not be ashamed, assuming you are male. :-)
There is a well-known engineering term (I am not an engineer, so it must be well-known): RTFM

[steveinaz]

My buddy was going thru a struggle with his combo VCR/DVD player. Turns out, PAGE 2 of the manual says: "If you want to watch a DVD thru HDMI, you must first disconnect the composite video out cable" (for the VCR)...

To which I told him "that's why I told you not to buy that damn combo player.." you cheap ass. LOL

[GV#27]

why did they invert them on the pre in the first place?The likely result of using a simple, single ended gain stage.

[DarqueKnight]

Adding more fuel to the fire and more aggravation to your listening experience is the fact that some record companies intentionally produce all their recordings in inverted phase. Some record companies do this unintentionally due to unawareness of the phase characteristics of their recording equipment.

Some preamps come with a phase inversion switch because of these types of recordings.

When I bought a Nakamichi CA-5AII preamp, it came with a sheet in the owner's manual that listed the record companies known to produce phase inverted recordings.

[SDA SRS 1.2]

That's why I enjoy the "Absolute Phase" switch on my Carver C-16 Preamp. It's fun to experiment with it on different recordings for best sound. :)

[CoolJazz]

I mean, if reversing the wires on the amp is required as they told you, why did they invert them on the pre in the first place?
If it's single ended, then it's not possible to just reverse the wiring. Needs another stage or a transformer.

If a circuit has an odd number of stages, then it's typically inverting and if even, then non-inverting. If you can accomplish what's needed in the unit and wind up with an odd number of stages, then as a manufacturer, you have to decide if you want to add the extra stage and expense, just to be non-inverting.

I'd say kudo's to CJ for resisting the easy way out and keeping the design simplier and cheaper with the caveat of needing to either account for it later with wiring or by nature of another piece in the system also being inverting.

CoolJazz

[dkg999]

DK - we could start another heated debate with several thousand posts on the issue of phase inversion in recordings! I've seen the debate on that spiral out of control on other forums.

[mhardy6647]

DK - we could start another heated debate with several thousand posts on the issue of phase inversion in recordings! I've seen the debate on that spiral out of control on other forums.

Yeah, I ain't going there. :-) I suspect that perfect phase hearing may be like perfect pitch. Some people have it, some don't.

[GV#27]

we could start another heated debate with several thousand posts on the issue of phase inversion in recordings! I've seen the debate on that spiral out of control on other forums.Yep its contriversial stuff ,ever heard of Clark Johnsen and the Wood effect?

[steveinaz]

I witnessed the wood effect....this mornin about 4:55 am, while spoonin the wife.

[DarqueKnight]

DK - we could start another heated debate with several thousand posts on the issue of phase inversion in recordings! I've seen the debate on that spiral out of control on other forums.

Awwwwww......I wasn't intentionally trying to provide bait for our ever increasing troll population.:(

[GV#27]

I witnessed the wood effect....this mornin about 4:55 am, while spoonin the wife.
Oooops should have known someone would go there.:D



Johnsen is a hard core absolute phase guy and he even wrote a book about it called the Wood Effect.I have'nt read it but understand it to be an interesting read.

[mhardy6647]

Awwwwww......I wasn't intentionally trying to provide bait for our ever increasing troll population.:(

Face it... you're just a...

(wait for it)


master baiter.


(sorry... sorry)

[CoolJazz]

Yep its contriversial stuff ,ever heard of Clark Johnsen and the Wood effect?
I have a friend that generally leaves a scope attached to the amplifier output. You can see on some kinds of material a very visible asymmetrical pattern. Asymmetrical meaning more information going positive or negative. This is often obvious on things like a solo trumpet or trombone, sometimes on certain singers voices. Some recordings, not much visable at all!

But when you can see a level of asymmetry, you can hear the difference when you flip phase. In his case, a flip of a switch at the preamp.

The only reason for it to be controversial that I can think of, is if the music you happen to listen to is so processed that natural musical patterns have already been squeezed out of it. And that could mean most all modern music for the masses treated to the normal sweetening and processing. That and that as pointed out, the general lack of uniformity to absolute phase in the music that's available.

On the right music, it can be quite stunning the difference!

CoolJazz

[GV#27]

The only reason for it to be controversial that I can think ofBy controversial I meant there are those that feel maintaning AP is important and audibly significant and those that think it not.


On the right music, it can be quite stunning the difference!

Therein lies the key.

[ben62670]

OK today I flipped my room. With the room changed the tweeters sound better in phase. Before It sound better with the tweeter out of phase and the sub and mids in phase.
Experiment guys, and gals.
Ben

[GV#27]

With the room changed the tweeters sound better in phase. Before It sound better with the tweeter out of phase and the sub and mids in phase.
Thats a different thing than absolute phase.What you are doing is changing the phase relationships between the drivers in a system.Aswell only one of the tweeter polarities should give the best results regardless of room position.


here is a good diagram on absolute phase.http://www.omegamikro.com/Absolute_Phase.html

[danger boy]

why would they build a pre amp that is phase inverted? what are the benefits of that?

[ben62670]

Big edit! Do not reverse the speaker wires on SDA's to change phase!

[heiney9]

why would they build a pre amp that is phase inverted? what are the benefits of that?

Al, reads posts 1-27 :) . My Adcom also has a phase invert switch, as well as my Adcom dac.

[ben62670]

H9 please send me your 750 for full testing. I shall return it in two weeks time.
Thanks
Ben

[GV#27]

why would they build a pre amp that is phase inverted? what are the benefits of that?see posts#13 and 16.

[lanion]

rtfm noob