phase inversion

Ricardo

GV#27 wrote: »

No,reverse speaker wires only,reversing the driver polarities also will just get you back to normal phase where you started.Be sure to keep the common ground strap on the amps neg terminals.

I wouldn't do this (with SDA's).

First, at the speakers crossovers, where a common ground is expected, it will get an "uncommon" positive signal. I am not sure what will happen at the speaker side, but I don't think it will be good.

Second, and where I was coming from on my earlier post, if you are using a blade-blade interconnect you would actually be connecting the amp's red binding posts together (blade-blade IC ties together the negative posts at the speaker; not a problem because you are supposed to use a common ground amp.... but if you connect the red wires there, the amp will see its two red posts tied together. I don't think this would be a good thing).
This will not happen with the pin-blade IC, and I am not sure what would happen with the AI-1 or whatever that one is called.

W WALDECKER

Hey George,If your preamp inverts phase and you reverse your connections at the loudspeakers you will have correct phase regardless of if you are using SDA or conventional loudspeakers. the idea behind inverted phase in a preamplifier is to eliminate an additional stage being added to the circuit is to put less parts in the signal path for superior sonic performance.thanks....WCW III

george daniel

Gads,, I understand,, then confused,then understand,then confused,, I'm going to use my reference track,, then reverse the wires and take notes,,I'll get back to ya'll with my impressions.

Ricardo

Hope you don't blow up any drivers.

Systems

Ricardo wrote: »

if you are using a blade-blade interconnect you would actually be connecting the amp's red binding posts together..

If thats so then it would be problematic.In that case reversing the polarities of each of the drivers only (not speaker wires)will get you back to absolute phase without shorting the hot outputs of the amp.Again the results may or may not be worth the hassle.

george daniel

Ricardo wrote: »

Hope you don't blow up any drivers.

Nope,, they won't blow,done it before,, I'm using the p/b interconnect,,I'm gonna step away for a minute,think this thru,and get back with what I hear.Keep me in your thoughts and prayers.;)

CoolJazz

Here is a quote from the manual for an old Hafler HD-120 amp which is representative of a common ground amp...

"The MAIN black output terminals of the DH-120 are connected together, and grounded to the chassis." "You must be sure that the '-', ground or shield connection....goes to a Main Black terminal on the DH-120. NOTE: No such connection may be made when the DH-120 is connected for bridged mono operation. Whenever you intend to use an external device employing a common ground connection, you must be certain of correct wiring polarity, because the RED amplifier terminals must NEVER be connected together."

I added the bold type. So again, flipping the red and black at either end of the speaker wire going into SDA's is very, very bad idea!! On other speakers without the cross-connection, this is commonly done both on purpose and accidently...and it is fine!

Absolute polarity is audible IF the source has been recorded with all sources the same polarity. This is more likely then, if it's a minimally mic'ed situation like on higher quality label releases. With a scope attached to amplifier outputs, its pretty noticable if you have greater positive or negative going symmetry and flipping it to positive is pretty audible!

On the standard commercially released, multi-mic, Pro-Tools assembled kind of music, its unlikely to be noticable at all. But on the good stuff with all matching polarity its very noticable and really nice sounding. But even then, the phase may differ between various recordings, so the phase reversal switch is very nice to have!!

CoolJazz