E
ecc83
Well-known member
Thank you Rob. "Valve watts" are indeed louder than "solid state watts" and there are good, solid engineering reasons for this. Valve power stages and especially GUITAR amp power stages do not employ nor need any protection circuits*. You can just drive ***t off them and they just get louder and more distorted. Another reason is that amps such as the AC30 use no Negative Feedback. The result is that the amp has a high, for a PA, source resistance, in the case of the Vox about 50 Ohms. This means they can " beat" Thermal Compression" in loudspeakers so, as the voice coil resistance rises with temperature the valves can up the drive voltage and keep pumping the power into the speaker. Solid state amps are voltage limited. 30W into 16 Ohms is 22V rms and with a tranny amp that's all you get.
Of course, the AC30 speakers are also around 100db/W/m in sensitivity whereas those in most columns and PA speakers a good 10dB lower. You would need an exceptionally large, powerful and expensive studio monitor to match an AC30!
*You can of course wreck one if you drive it without a load but a well designed amp will stand this abuse for longer than you might think.
Dave.
Of course, the AC30 speakers are also around 100db/W/m in sensitivity whereas those in most columns and PA speakers a good 10dB lower. You would need an exceptionally large, powerful and expensive studio monitor to match an AC30!
*You can of course wreck one if you drive it without a load but a well designed amp will stand this abuse for longer than you might think.
Dave.
