Please help me not blow my speakers!

jpatt2 · #1 07-18-2011, 05:00 AM

I recently acquired an Ampeg V4. I am new to all tube amps, but I know that the Ampeg book says they were closer to 120w as opposed to the advertised 100w rating. I'd like to avoid the tube watts vs ss watts arguement...So how many watts should my speaker cab be able to handle to not blow? Perhaps if someone knows the max sound pressure levels of a v4 that would help me pick a speaker?

rodl2005 · #2 07-18-2011, 05:17 AM

More than 50 & less than 2000. U really won't hurt your speakers unless you run that amp into a low power rated guitar cab as far as I know. Especially as it's an all tube amp, shouldn't hurt most decent quality bass cabs.
Best to run it into a good 2x12-2x15, 410 etc
I ran mine into an 700w rated 610 with great results. Also into a 300w 1x15 too

danomite64 · #3 07-18-2011, 05:25 AM

I managed to fry an old Altec 15" with my old V4-B about 15 years ago. It's the only speaker I've ever blown, and it took some doing. That being said, the used EV 15" I replaced it with has stood up and I've probably driven it harder. I was told the Altec was rated at 200 watts, but I think it was more like 100.

billfitzmaurice · #4 07-18-2011, 06:09 AM

Quote:

Originally Posted by jpatt2

So how many watts should my speaker cab be able to handle to not blow?

At least one.
AMPS FAQ!! Info on OHMS, Allsize RIGS-OverUnderPowerCabs DIY TechTalk-Links

jpatt2 · #5 07-18-2011, 09:12 PM

Thank you so much for your replies everyone, and sorry to post something answered in the faqs!

JimmyM · #6 07-18-2011, 09:48 PM

Quote:

Originally Posted by danomite64

I managed to fry an old Altec 15" with my old V4-B about 15 years ago. It's the only speaker I've ever blown, and it took some doing. That being said, the used EV 15" I replaced it with has stood up and I've probably driven it harder. I was told the Altec was rated at 200 watts, but I think it was more like 100.

And that is the difference between thermal rating and displacement limited rating (or as I call it, real world rating). The V4b can easily hit peaks of 200w or more when you crank it into distortion, and cabs rated at 200w can be blown quite handily with amps that do 100w RMS.

So if you plan on cranking it into the red, I'd say get a cab that can do at least 400w thermal.