Attenuator and impedance question

billando

Hi all. I have just ordered the marshall 1974cx 1 x 12 cab to go with my 1974x 1 x 12 combo. If I wasn't using an attenuator it would be set to 8 ohms for using combo with cab. My fryette power station attenuator has impedance selections for amp in and speaker outs. Would it be combo set to 16ohms, to input of attenuator set at 16ohms then 8ohm outputs to the combo and cab or would everything be set to 8ohms? Any help much appreciated. 

ICBM

The attenuator must always be matched to the amp, since it's the load that the amp sees. Matching the attenuator to the cab(s) is less important, although if you have the option it's best to do so.

But - the Fryette is not an attenuator... it's a dummy load and re-amp system. This means that the input and output are totally independent, so you need to match the input to the amp and the output to the cab(s) regardless of whether they're the same impedance or not.

billando

Ok so should i hook it up like I described in my first post? The amp, power station input and outputs all have impedance selectors. Thanks. 

ICBM

If all three are selectable I would set the amp and the Power Station input to 16 ohms - using the whole winding on the transformer, which maximises efficiency - and the Power Station output to 8 ohms if you're running both cabs.

billando

Perfect thanks. I find the 1974x is a perfect volume for my band non miced. It just lacks a little punch I'm hoping the extension cab will provide. If anyone has experience with this I'd be glad to hear it. 

grungebob

I’ve an orange dual dark that has an attenuator, Orange make some blurb about it not being a traditional attenuator, I’m guessing it’s really just a master volume?

ICBM

grungebob said:

I’ve an orange dual dark that has an attenuator, Orange make some blurb about it not being a traditional attenuator, I’m guessing it’s really just a master volume?

Reading between the lines of the blurb, I'd guess it's either a post-phase-inverter master volume, or some sort of power scaling. They say that it doesn't affect the relationship between the amp and the speaker so it's safe to say it isn't post-power-stage, and given the location of the pot on the front panel it can't be a large-size 'rheostat' type control.

So basically it doesn't affect the impedance matching at all.

grungebob

ICBM said:

grungebob said:

I’ve an orange dual dark that has an attenuator, Orange make some blurb about it not being a traditional attenuator, I’m guessing it’s really just a master volume?

Reading between the lines of the blurb, I'd guess it's either a post-phase-inverter master volume, or some sort of power scaling. They say that it doesn't affect the relationship between the amp and the speaker so it's safe to say it isn't post-power-stage, and given the location of the pot on the front panel it can't be a large-size 'rheostat' type control.

So basically it doesn't affect the impedance matching at all.

Yeah I don’t get it , they also give you the half power option on the front panel right next to the attenuator/master volume. 
Either way sounds goo though.