I never knew this...

[hermitcrab]

I picked up the VM 1296 mentioned on a earlier post... the cartridge was broken so working with Gary Stork , he supplied the correct replacement... also one wire was off the cart plug , so when I went to re-solder it on, I noticed the grounds were out of phase on the plug. one ground on the lower pin and one on the upper ... I asked Gary because it sure looked factory to me ... and to my surprise he claims that is the way tetrad carts are suppose to be to due internal configuration... I never knew that before... a few months ago I got one of Gary's tetrad replacement kits for my Magnavox along with the wiring and plug ... it was not wired like that, it was wired normally... so is my new cart on the magnavox 180 out of phase?... waiting on a response from Gary on that ....Gary sent me a diagram as it is suppose to be...

[TC Chris]

The best test for phase is listening. Usually it's speaker phasing we worry about. But you could try reversing the speaker leads, if that's easier than reversing cartridge wires, to see if that sounds better or worse. If reversing the speaker leads sounds better, then the cart is out of phase. If it sounds worse, the cart is AOK. Use a mono record.

By the way, when I say "Better," I mean that the sound should come out of the middle and the bass should be good. "Worse" means that you get some sort of fake-stereo separation effect from a mono source, and the bass will be weak.

Chris Campbell

[hermitcrab]

My surprise was some cartridges are made to be wired out of phase ... when I built the fisher , if you turned up the bass it would shake and rattle almost like a 60 cycle hum... turned out the pickering cart on the TT was out of phase , once I reverse the leads to the cart the bass shaking went away , I blamed that on being wired out of phase... but purposely wiring them out of phase is a new one on me...

[19&41]

I know the phasing is supposed to have an effect on bass. Why wouldn't the input phasing have the same effect? Out of phase stereo outputs are supposed to enhance bass.

[TC Chris]

Actually, out of phase speakers tend to cancel bass because one speaker is pushing while the other is pulling. And an out of phase input will make in-phase speakers behave as if they are out of phase. Try it. Play a mono source on a stereo device with speakers with good bass response. If everything is in-phase, the sound will seem to come from right between the speakers and bass will be good. If something is out of phase, the sound will not be localized in the middle and the bass will be weak. That's how I verify phase when I'm using speaker wires that aren't polarized with colors or stripes or whatever.

Chris Campbell
TC

[Motorola minion]

I found out that same thing recently on a low-end Philco I sold, Tetrad is the only cart small enough to fit the tonearm on this particular VM-made player. I used my test record to confirm the phase was correct and giving all the bass it can.

For this reason, I would not ever use a three-wire plug if given the choice. That way, you can switch the wires at the RCA plug side. Who wants to solder anything to a cartridge plug that tiny?

Note also: Tetrads come in three body colors, each correspond to different output voltage . A red body is .15 volts, gray is .29 volts and black is .5 volts.

Output voltage is very important when matching originals because the preamplifiers differ in how much input signal is required. For instance, a portable player may need all of that .5 volts, with only one tube preamp stage before the output. My '63 Motorola SK112 is the other extreme, where a .15 volt output is literally triple-amplified via 12AX7's before heading to the 6V6 outputs! RCA's using 6CG7s need the in-between of .3 volts.

[Firedome]

Dave: I have a VM 1200 (I think) that it looks like I won't be using if you want to chase that ol' devil around a bit more! lol

[hermitcrab]

Note also: Tetrads come in three body colors, each correspond to different output voltage . A red body is .15 volts, gray is .29 volts and black is .5 volts.

the ones I have are yellow plugs ... what output are those?

[Motorola minion]

I saw some Tetrad that had a fourth voltage available. There was no mention of the colors used.

[hermitcrab]

That is the color Gary@VM sent me for the VM changer I have .... never thought to ask him what voltage yellow was...