8ohm/16ohm cabs at same time?

burnscs · Post by **burnscs** » Sun Feb 23, 2014 7:27 pm

My AD30 has 2 8ohm sockets and 1 16ohm jack, can I use one 8ohm for my 8ohm cab then one for the 16ohm at the same time? Will the world implode if I attempt this?

DiabloS · Post by **DiabloS** » Sun Feb 23, 2014 7:59 pm

I'm pretty sure they're not meant to be hooked up this way. Someone correct me if I'm wrong. Usual method is 2 16 ohm cabs into the 8 ohm outputs.

Valvelust · Post by **Valvelust** » Sun Feb 23, 2014 8:10 pm

DiabloS wrote:I'm pretty sure they're not meant to be hooked up this way. Someone correct me if I'm wrong. Usual method is 2 16 ohm cabs into the 8 ohm outputs.

Always the dilemma of having one 8ohm and one 16ohm cab and wanting to use both...and no way to rewire to matched impedances.

Correct, if using two 16ohm cabs you would connect each to the 8ohm outs, using one cab connects to the 16ohm out.
Otherwise you will have a mismatch and subjects the output transformer

iblastoff · Post by **iblastoff** » Sun Feb 23, 2014 10:00 pm

orange really needs to address the confusion of those outputs.

OU818 · Post by **OU818** » Sun Feb 23, 2014 11:35 pm

iblastoff wrote:orange really needs to address the confusion of those outputs.

I am surprised they have stuck with these speaker outputs and not just installed a 16/8 switch with 2 parallel outs.

Randy Bass · Post by **Randy Bass** » Sun Feb 23, 2014 11:55 pm

burnscs wrote:My AD30 has 2 8ohm sockets and 1 16ohm jack, can I use one 8ohm for my 8ohm cab then one for the 16ohm at the same time? Will the world implode if I attempt this?

Connecting an 8-ohm cab and a 16-ohm cab in parallel will result in a 5.33-ohm load. It may not be a severe mismatch, but do so at your own risk. As always, I would recommend resisting the urge to connect everything you own that has a 1/4" jack together at the same time.

Doctor Volume · Post by **Doctor Volume** » Mon Feb 24, 2014 12:55 am

Randy Bass wrote: As always, I would recommend resisting the urge to connect everything you own that has a 1/4" jack together at the same time.

Great advice.

Gladmarr · Post by **Gladmarr** » Mon Feb 24, 2014 1:01 am

Keep in mind that if you do hook the two cabs up, while the load will be 5.33 ohms, it wil also be imbalanced. This means that the 8ohm cabinet is going to see more power than the 16ohm cabinet. The 8ohm cabinet is also going to be louder than the 16ohm cabinet.

Jondog · Post by **Jondog** » Mon Feb 24, 2014 1:01 am

OU818 wrote:
iblastoff wrote:orange really needs to address the confusion of those outputs.
I am surprised they have stuck with these speaker outputs and not just installed a 16/8 switch with 2 parallel outs.

I'm in the process of designing/building an amp and was thinking about doing parallel jacks with a switch or the Orange way. Looking at the design I realized the way Orange does it is actually physically pretty much the same with three holes and three compponents and mechanically better as there are no moving parts that could fail or make poor contact . Their output transformers don't have a 4 ohm tap so you would never run two 8 ohm cabs in parallel.

burnscs · Post by **burnscs** » Mon Feb 24, 2014 1:26 am

Whelp no need to worry anymore.

The 8ohm 212 cab is from the 70's, and when I hooked the ad30 up to it I got no sound from the amp just the power light lite. I checked the fuse and sent away for new JJ tubes.

I put the tubes in and hooked it up to me 412 and it ripped. I hooked it up to two 16ohm cabs using the two 8 ohm sockets and it ripped. In a good way of course.

I put the head back Into the 8ohm 212 combo again and used one 8 ohm socket and the amp fired up then went dead. No power no sound, nothing at all. Fuse looks good.

After punching the wall a bunch I am stumped.

The 8ohm cab works fine with other heads by the way. Who can solve the mystery. I have one possible solution but ild love to hear from you guys since you actually know what you are talking about!!!!:)

a.hun · Post by **a.hun** » Fri Feb 28, 2014 9:02 am

Intermittent connection in the cab? (One of the worst things you can subject a valve amp to BTW!)

Get it and your amp checked out properly.

And to answer your original question...

burnscs wrote:My AD30 has 2 8ohm sockets and 1 16ohm jack, can I use one 8ohm for my 8ohm cab then one for the 16ohm at the same time? Will the world implode if I attempt this?

No and no. The world will survive but no you shouldn't (ever) use the different impedance outputs at the same time. The 8 ohm output is just a partial tap of the (full) 16 ohm transformer winding. Using both means that this part of the coil will be running current to both speakers and may well burn out.

The two 8 ohms outputs are really just one output BTW, just split to two output sockets linked in parallel. Using either or both of those together with the right impedance cab(s) is fine.

Andy

Post by **bclaire** » Fri Feb 28, 2014 6:35 pm

For the record, Orange addresses this in the Sticky at the top of the forum which says First time poster please read. It spells out how you connect cabs and also the manuals spell it out too.

To recap

ONE 16 ohm cab into the 16 ohm out
ONE 8 ohm cab into one of the 8 ohm outs
TWO 8 ohm cabs into the two 8 ohm outs.

That's it for commercially made cabinets of 8 ohm or 16 ohm. You cannot mix different value cabs nor use a 4 ohm cab. At least, not if you don't want to replace your output transformer when it blows.

burnscs · Post by **burnscs** » Sat Mar 01, 2014 1:36 am

Well I think I figured out what was causing the problems. There are four or five screws on the smaller transformer that hold the magnet in place. For some reason there is currently only one in mine and it was very loose.

When the head would be played out of the combo it was alright. When I would put it in the combo the head is resting upside down. This was enough force for the magnet to move, and no longer be snug where it should be.

This is what I think killed the rectifier tube the first time, and the main fuse the second time. I have been playing it with my 3 16ohm cabs and I have had no issues. I am still scared to plug it back into the 8ohm 212 though however.

Could this be what did it? My OR80 and TT play great through the 8ohm 212.

Puckhog · Post by **Puckhog** » Sat Mar 01, 2014 2:38 am

iblastoff wrote:orange really needs to address the confusion of those outputs.

Ya think?

Puckhog · Post by **Puckhog** » Sat Mar 01, 2014 2:40 am

bclaire wrote:To recap

ONE 16 ohm cab into the 16 ohm out
ONE 8 ohm cab into one of the 8 ohm outs
TWO 8 ohm cabs into the two 8 ohm outs.

Or to recap . . .

Use an attenuator with variable impedance controls.