SDA trouble shooting - where to go next?

quadzilla

I'm still loving my 2.3 TLs, but even when I first hooked them up, I noticed that the SDA effect in the left channel didn't seem as strong as in the right. After a few days of close listening, and judicious use of the channel inverter switch on my pre, I'm certain that it isn't. I've verified the following:

Alignment - speakers were aligned to the same plane using a laser sight, and to the same distance from the back wall and side walls.
Mono signal - balance to left results in right dimensional drivers on, left stereo drivers muted.
Mono signal - balance to right results in left dimensional drivers on, left stereo drivers muted.
Battery test - all drivers move in unison on both speakers.
Verified amp - used my backup common ground amp, same issue.
Verified pre to amp ICs - tried a spare set, same issue.
Verified source to pre ICs - tried a spare set, same issue.

What's interesting is that if I flip the phase (by reversing the speaker cable) at the amp on the left channel, I get a strong SDA effect, the same as the right channel, but the image is pulled hard to the left. Flipping both channels just results in the original issue.

The rest of the set up is: CJ pre, tube mono blocks, AI-1 SDA IC.

From reading the SDA trouble shooting guide, it seems like most SDA issues are related to phase. And the fact that if I flip the phase on the speaker cable to the left channel gets a strong SDA effect, I think it is a phase problem. But I can't figure out where to look next. Or does the fact that even though all the drivers in the left channel move together when testing with a battery still allow for the possibility that the SDA drivers in one or both channelse are out of phase?

TIA

F1nut

Mono signal - balance to left results in right dimensional drivers on, left stereo drivers muted.
Mono signal - balance to right results in left dimensional drivers on, left stereo drivers muted.

That isn't right.

It should be as follows;

Mono signal - balance to left results in left channel stereo drivers on, right channel dimensional drivers muted.
Mono signal - balance to right results in right channel stereo drivers on, left channel dimensional drivers muted.

Schurkey

quadzilla wrote: »

Mono signal - balance to left results in right dimensional drivers on, left stereo drivers muted.
Mono signal - balance to right results in left dimensional drivers on, left stereo drivers muted.

That's got to be part of the problem. I'd expect with a mono signal, the balance to the left, the left stereo drivers should not be muted.

quadzilla wrote: »

Battery test - all drivers move in unison on both speakers.

That's good.

quadzilla wrote: »

Verified amp - used my backup common ground amp, same issue...
...The rest of the set up is: CJ pre, tube mono blocks, AI-1 SDA IC.

What happens with the common-ground amp and a regular SDA interconnect cable?

Is that a home-made AI-1?

george daniel

^^^^ common ground amp and sda cable^^^^^^^^^---good point.

Please let us know what you find.

quadzilla

Schurkey wrote: »

That's got to be part of the problem. I'd expect with a mono signal, the balance to the left, the left stereo drivers should not be muted.

Crap, I wrote that backwards. It should be:
Mono signal - balance to left results in right dimensional drivers on, right stereo drivers muted.
Mono signal - balance to right results in left dimensional drivers on, left stereo drivers muted.

Sorry for that eff up.

It's a Polk AI-1. I haven't tried a standard SDA cable and common ground amp yet.

george daniel

just a thought,,but does the CJ invert phase?

Toolfan66

quadzilla wrote: »

Crap, I wrote that backwards. It should be:
Mono signal - balance to left results in right dimensional drivers on, right stereo drivers muted.
Mono signal - balance to right results in left dimensional drivers on, left stereo drivers muted.

Sorry for that eff up.

It's a Polk AI-1. I haven't tried a standard SDA cable and common ground amp yet.

I just did the same test and that's how mine are as well.

Mono, balance to the right stereo is to the right on the left dimensional drivers on stereo drivers muted.

Mono, balance to the left stereo is to the left on the right dimensional drivers on stereo drivers muted.

quadzilla

Well... common ground amp and standard SDA cable works fine. Uhm... AI-1 wired out of phase?

quadzilla

george daniel wrote: »

just a thought,,but does the CJ invert phase?

Not according to http://www.conradjohnson.com/It_just_sounds_right/a-PV2.html

Phase Response: Line Stage phase correct, Phono Stage phase correct

I opened the AI-1. Could someone with a known good cable check against this pic? I'm assuming the transformer doesn't phase invert? If so, then the AI-1 is definitely out of phase. But what I don't understand would be why when I reversed it, the problem didn't switch to the other side.

F1nut

quadzilla wrote: »

Well... common ground amp and standard SDA cable works fine. Uhm... AI-1 wired out of phase?

Possible. It's also possible that the connections on the back of the binding post are wired incorrectly.

If you remove the top of the AI-1, you should see the black and white wires reversed on the other side of the transformer.

quadzilla

F1nut wrote: »

Possible. It's also possible that the connections on the back of the binding post are wired incorrectly.

If you remove the top of the AI-1, you should see the black and white wires reversed on the other side of the transformer.

OK, well, that answers the question I just asked.... I checked the wiring on the cups. It's the same on both sides. I didn't pull the passives to check the crossover though. Guess that'll be next.

Toolfan66

So do I have the same issues?? My speakers sound great and the front stage is wide and deep.

quadzilla

TOOLFORLIFEFAN wrote: »

So do I have the same issues?? My speakers sound great and the front stage is wide and deep.

Unless one of your channels sounds like it never expands past one of the speakers, probably not. That's the effect I have. The right side extends at least to the wall. The left channnel seems stuck to the speaker.

Also, now I'm more confused. I strapped the grounds together on the monoblocks and ran the standard SDA cable. I had no SDA effect at all at the point from either channel.

Toolfan66

My speakers are working as they should and are wired correctly.. quadzilla you had me second guessing things LOL!!!

I have some media that sounds stronger on the right channel now and then and I have to say it f#@k's with me sometimes..

quadzilla

Well, thought I'd found it.... not so much. Seemed to work for a minute, but either it came back or I was just fooling myself.

Toolfan66

Awesome!!!! you should build a Dreadnaught!!! ;-0

OldmanSRS

quadzilla wrote: »

Crap, I wrote that backwards. It should be:
Mono signal - balance to left results in right dimensional drivers on, right stereo drivers muted.
Mono signal - balance to right results in left dimensional drivers on, left stereo drivers muted.

This will be the norm if your speakers are wired correctly but you have them physically reversed L to R.

quadzilla

OldmanSRS wrote: »

This will be the norm if your speakers are wired correctly but you have them physically reversed L to R.

No, that's correct. With a mono signal and full left balance, the right stereo drivers should be muted and the right dimensional drivers should activate according to the SDA trouble shooting guide.

F1nut

For the record, my post in #2 is wrong. I was thinking stereo instead of mono.....sorry for the confusion.

quadzilla

For what it's worth, this turned out to be a couple of things. One is that the AI-1 cable is twitchy. I sort of resolved that by running a coat hanger from the bass bolt down and making a hook to take the strain off the connector. The other is that the end caps were actually pretty off, so when I aligned the speakers, the right was toed out and the left was toed in by a fair bit. But at least it's working now. And I have to tighten the end caps...

Schurkey

quadzilla wrote: »

the ai-1 cable is twitchy.

Dreadnaught!