Vt40 head with two 4x12 cabs. Phasing issues?

[cthendrico]

I live in Idaho and so good Ampeg stuff rarely pops up. However over the last 10 years I have acquired and refurbished two Ampeg 4x12 cabs and converted a vt40 into a head unit. I'll post a picture below. For the speaker cabs I loaded one cab with celestion heritage g12h 55htz greenbacks and in the other cab celestion alnico's. All speakers 16 olm. The cabs have been installed with modern multiload inputs kinda like modern Marshall cabs have that let you select 16 olm mono, 8 olm stereo, and 4 olm mono inputs while using 16 olm speakers. I have one cab plugged into the regular speaker Jack on the vt40 and the other cab into the extension amp Jack on the vt40 with both cabs being ran on 16 olm mono selection and the vt40 on the 8 olm selector.

However I'm concerned about phasing issues and was hoping if I showed you amp gurus the cabinet semantics and with knowledge about the vt40 amp of you could tell me if I'm getting the most out of my set up.

[cthendrico]

Help?

[jjmt]

I actually looked at all the schematics yesterday and they kind of made my brain hurt. I personally decided to let this one sit for someone else because I don't have any of the same equipment and you didn't really specify a problem. What phasing issue are you actually concerned about? Happy to think it through with you.

[cthendrico]

That's my problem! I can't read schematics on the Cabs I have A PLUS I don't really understand how the vt40 works with the extension cab Jack. For example is the vt40 wired in such a way that the regular speaker Jack and the extension cab Jack wired in such a way that two different cabs will be in phase? Especially considering the schematics that I attached for my cabs. (please note: those schematics show different wiring schemes for different speaker configurations and olm speakers. For my proposes just look at the 4x12, 16 olm schematic.

I guess my main concern is when I have them both plugged in I feel like I might be getting some phase cancellation. However it appears that all the speakers Congress are expanding in and out the same? Did that make sense?

[cthendrico]

I actually looked at all the schematics yesterday and they kind of made my brain hurt. I personally decided to let this one sit for someone else because I don't have any of the same equipment and you didn't really specify a problem. What phasing issue are you actually concerned about? Happy to think it through with you.

See above. Thanks

[jjmt]

See above. Thanks

I did read the post, of course. So maybe I was a bit short with my question. If the speakers are all moving in the same direction, why do you think that you have a phase issue? Is it because you hear a change in the amount of audible bass? That would possibly indicate an impedance mismatch between what your cabs are showing your amp and what it is expecting to see.

I'm kinda hoping that Hangman will report in here, as he probably knows exactly how the speaker jacks on your amp are wired.