Single Parallel jack wiring

[RockinRocket]

http://ceriatone.com/images/layoutPic/m ... iatone.jpg

Is this single/parallel wiring for the normal channel? I don't know how to read jack wiring schematics well. I used this before and used it again for my 18 watt. Just want to be clear of the circuit I used.

[M Fowler]

No that shows hi/low both having their own triode.

Single input would be one jack.

Parallel jacks is two jacks but going to same triode.

Single input but going to parallel triodes?

[sluckey]

The 18W normal channel input jacks are supposed to operate such that when plugged into the low jack signal is sent to only one grid of a pair of parallel triodes and the high jack would be grounded out.

Plugging into the high jack will send the signal to both grids for parallel operation.

Only the normal channel is wired like this. The trem channel has the more common hi/lo jack circuit.

That Ceriatone schematic is not wired like the original. This drawing may be a little easier to see the parallel switching. Compare the schematic to the layout.

http://home.comcast.net/~seluckey/amps/18w/18w.pdf

You may also want to look at the bottom of page 8 of this pdf...

http://home.comcast.net/~seluckey/amps/ ... apbook.pdf

[RockinRocket]

Thanks guys. So what kind of input is the ceriatone?

http://home.comcast.net/~seluckey/amps/18w/18w.pdf

On page 2 with the layout. Would connecting the ground buss wire from the pots to in between the high and low jack make no difference than what's shown on the layout?

[sluckey]

The Ceriatone schematic shows the LO jack connected to one triode and the HI jack connected to the other triode. They will operate and sound exactly the same.

Either way should be fine for connecting the ground buss to the input jacks.

[RockinRocket]

The Ceriatone schematic shows the LO jack connected to one triode and the HI jack connected to the other triode. They will operate and sound exactly the same.

Either way should be fine for connecting the ground buss to the input jacks.

That's hilarious I kept switching the inputs trying to find some nuances. That explains why I didn't.
Mark mentioned that in the first reply don't know why I didn't process that. Wonder why ceritone did that? Perhaps they botched up the layout?

[martin manning]

That is the wiring shown on original Marshall 18W schematics.

[sluckey]

You're right. Sorry for the bad info.

[RockinRocket]

That is the wiring shown on original Marshall 18W schematics.

So you are saying Ceritones layout is from the original 18 watts schematic? 18 watters did not have parallel triodes? If not what was the purpose of the hi lo jacks in this amp?

[tubeswell]

Schematic. Requires no more parts than a normal 'fender hi-lo' input. If both jacks are plugged in = stereo inputs.

[sluckey]

So you are saying Ceritones layout is from the original 18 watts schematic? 18 watters did not have parallel triodes? If not what was the purpose of the hi lo jacks in this amp?

The plates and cathodes are parallel but the grids are separate. This provides excellent isolation between two instruments that are connected at the same time. I don't know that the original jacks were ever labeled hi/lo. Never seen one.

In today's world where you seldom if ever see more than one instrument plugged into an amp, it makes a lot of sense to make the simple mod to the input jacks to provide a single/parallel option.

Here's the schematic that is touted to be the original 18W. As martin manning said, the Ceriatone normal jack layout matches the original schematic.

[martin manning]

Schematic. Requires no more parts than a normal 'fender hi-lo' input. If both jacks are plugged in = stereo inputs.

Not stereo, but good for mixing two instruments. I don't know where the single/parallel triode input mod came from, or if it was ever used on production 18W amps. The 1974x reissue 18W does not have it.

[RockinRocket]

Not stereo, but good for mixing two instruments. I don't know where the single/parallel triode input mod came from, or if it was ever used on production 18W amps. The 1974x reissue 18W does not have it.

Yes that would make sense. I don't know why I thought they were parallel.. I think is was from watching the proguitar shop demo where he played both inputs

[jaysg]

hmm...this is about my only significant contribution to the 18W group. I pointed out that the original design is like some of the 50's Fenders where they seemed to expect more than one input to be used simultaneously. My idea was to use the 5E8-a design, so that you get one triode from the Lo input and parallel triodes from the Hi input...an actual difference that you can hear. I don't think the original amps indicate Hi/Lo for either channel. That's really a Fender thing.

Of the 'name' manufacturers, I don't know if any picked up that or not. Nik could have...I'll have to look at the thing.

[Ron Worley]

Could mess with the two triode's bypass cap and or resistor on one to give you different sounds- or remove the cap on one completely.