Headphones instead of speaker.

[jammybstard]

I'm sure this has been covered before somwhere but I'm not having much luck with my searching:
As the speaker has a huge effect on the sound of an amp, while tweaking I'd like to listen to the output directly into a pair of monitor headphones so I can hear the true tone of the amp before the Greenback does it's thing; is there a simple attenuator/filter circuit commonly used for this sort of thing?

[Jana]

I suppose if you want to have a colorless attenuator, just use an 8 ohm, 100 watt resistor. That should be mostly flat and lifeless in its curve.

What this will accomplish, I don't know. The speakers are a part of the amp and the speakers are what will be used in the end, so why tweak the amp for anything else?

A much better choice, in my opinion, is to use a known speaker cabinet. You already have a greenback--I doubt you could go wrong tweaking the amp to sound good with that speaker. Isn't that what you will be using in the end anyway?

[Structo]

Yes, you really do need to take the speaker coloration into consideration when tuning an amp.
I mean, that's what you're going to hear, so you need to take that into consideration.

Now if you plan on changing to a different set of speakers or new cab then you may have to adjust some cap and resistor values to make it your own.

[Merlinb]

I'm sure this has been covered before somwhere but I'm not having much luck with my searching:
As the speaker has a huge effect on the sound of an amp, while tweaking I'd like to listen to the output directly into a pair of monitor headphones so I can hear the true tone of the amp before the Greenback does it's thing; is there a simple attenuator/filter circuit commonly used for this sort of thing?

You should be able to hook a pot in parallel with the speaker, with the wiper to the phones, and adjust until you hear something. Use 5k for 30W or more, and 1k for less than 30W. Use cheap phones in case you burn them out with adjusting!