12VAC vs 12VDC Wall Adapter for 6J1 Tube Headphone Amp—What’s Inside?

Thanks in advance, this should be an easy question?
I built a small headphone amplifier that uses 2 6J1 tubes, I was disappointed when it didn't work although it did light up. Then I noticed it is 12VAC, not DC.  So I have only a basic understanding and have some formal training but it has been a while. I do understand how to build a basic dc power supply using a transformer and bridge rectifier and filter cap voltage reg. My question if you purchase a 12-volt ac wall brick at say 1 amp will it only have the transformer in it? I would think it would have a filter circuit? The kit amp has a filter circuit as it states in the manual.   This being said can I just hack out the rectifier from a dc wall wart? Manual says 12 volt 0.8Amp and does say not 13 as it will shorten the life of tubes. So 12-volt dc would be about 11volt ac in?Thanks again!Mark 

All power supplies have a transformer inside just to reduce the AC voltage. I found time ago a link where was described how is made the internal of power supply of Mac Book I suggest you the other our web site https://www.powerelectronicsnews.com/ where you can find a lot about power supply, also technical tutorial. 

Generally it is either AC or DC. It is the RMS  ( the equivalent heating value if you like, which is what you need for a  tube heater) value that matters in the case of AC, which is normally how the voltage on an adapter is listed. So one or the other. If the wall adapter is not used near its maximum rated power, the voltage can be higher than the name plate,  since the transformer regulation is often poor (the output voltage is specified for the maximum current drawn)Cheers,Richard