Originally Posted by tdbernard
So I need to find me a four ohm cab?
If you all think using an 8 ohm cab with this head could damage it, I'll start looking for a cab. I have always went that direction in ohms loads, I was always told it was fine.... But also told to never go too low in ohms. Example: 2 ohm load on a 4 ohm stable amp. Never dreamed the other direction would cause a problem??
For the record though, my old head had most likely been dropped in transit.. There was damage to the box that I had overlooked during my first un-boxing. Then, when I received my head back from repair, there was massive damage to the box and two Styrofoam corners were smashed into little pieces. I would guess my issues were caused by shipping.
Valve amps are the total opposite to transistor amps, impedance load wise, it is quite common for Valve amps to have switched output jacks
So if you forget to connect a cabinet or load, the switch shorts the output socket to 0 ohms to protect the amplifier from total destruction into infinity ohms which would happen in seconds playing at any gain.
So on a transistor amp you have a minimum recommended ohms, the load that the amp produces its maximum power at.
In effect your tube amplifier is presenting a transformer tap that
is the maximum ohms the amp can safely handle.
Also sometimes if you get it wrong, you can seriously endanger your life as follows:
last week a "know it all" young music tech student booked a rehearsal in my facility, was provided with an all tube amp rig all warmed up and standby off (I leave the amp with the standby off, gain down because the local University is only in its second year of existence, so no music tech students in my experience have yet fully grasped the function of a standby switch) but unknown to me, he wanted to test his transistor micro amp in via my old school cabinet and simply, without being polite enough to ask my advice or permission, unplugged my cab and plugged the lead into his pathetic little excuse for an amp, leaving my beautiful vintage tube amp that, does not have auto shorting output jacks because its old and British and therefore requires less idiot proofing in the design, unloaded! for the 4 hour period of the rehearsal.
The only thing that saved its life and incidentally his, was that there was nothing In the input.
Remember, "Violence is never the answer" but often makes for a very satisfying beginning.