Using a 100 watt head with a lower wattage cab?

[Vinny]

So I know that you should never hook a head to a cab that has a lower wattage and lower ohms, but basically I really want to get a 2x12 that has a single V30 and a single G12H30. So if this is even possible, what is the easiest way to do it? I can get the cab in either 8 ohms or 16 ohms. And the cab would be 60 watts (since 60 watt speaker + 30 watt speaker = 60 watts still according to every other forum.) I want a 2x12 for when I'm not playing club sized venues with my band, mainly for transportability and tone versatility (I have another 4x12 for my band's gigs).

The amp is a Blackstar HT-100. It has five speaker outputs on the back to the right in this picture-

(The fifth output is cut off in the picture, but it's just a single 1x16 ohm output)

I read that you can hook up an amp that is lower ohms than the cab by a 2:1 ratio. I also read that you can stick an attenuator in between the head and cab and attenuate it by 3db so it effectively is putting out the same power as a 50 watter, but the attenuators can get pretty expensive. And obviously you can pull out the outter or inner pair of power tubes to make it a 50 watter too, but this would just be a hassle to do and undo every single time I switched cabs and most would agree it really affects the tone. And moreover, I heard that you can hook it up just as it is but go easy on the volume?

Are there any other methods or ways or am I just completely out of my mind and am going to have to buy a different head? Lol
Thanks guys.

 

[Proggm]

"So I know that you should never hook a head to a cab that has a lower wattage and lower ohms"

It's not really like that. Of course, you must match impedances, but as long as you keep the master volume down to reasonable levels, it should be alright. Keep in mind you are never utilizing those 100w unless you push it to the max.

 

[Vinny]

So I should be fine using a 60 watt cab if I kept the master volume no higher than around 1/2 way?

 

[Wolfeman]

You are only as strong as your weakest link in a 2x12, so yes you technically have 60watts max, since the one speaker will 'blow' past the 30 watt point, while the other is making the same power.

You can't judge the wattage based on master volume setting, since all amps are different. But any reasonable volume on the amp should be fine through the cab. You would really have to crank it high to blow the speaker. You will no doubt hear the unpleasant sound of the speaker being over-driven if you put it to high, and will know when to stop on the volume knob.

If you want to stay safe, pull 2 tubes and half the impedance. Then you won't have any worries of going overboard.

 

[PaoloJM]

So I should be fine using a 60 watt cab if I kept the master volume no higher than around 1/2 way?

It's not as simple as that.
Volume controls are logarithmic and so ideally 1/2 way would be around 1/10th the output power.
However most valve amps are designed to begin over-driving the power amp by roughly half way up the dial onwards.
A JCM880 2203 reaches 100 Watts at about 11 O'Clock on the dial for example, after that it's over-driving and produces in excess of 100 watts.

I don't know the Blackstar series of amps but I'd guess that you'd want to stay below 10 O'Clock on the master, which is pretty darn loud anyway.

Wolf's suggestion of removing two power valves is also a valid one if you are really concerned.

 

[7string]

The V30 is rated for 60W.
You could get a Weber 1230-55 (H clone) and have it built for 75W.
But I think the H30 can hang. They have been abused for decades. Fuck it.

 

[Vinny]

Alright, thanks alot guys! And yea, I have been thinking about pulling the two power tubes, but like I said, everyone seems to agree that it really changes the sound. Guess I'll just have to try myself. Again, thank you!