1971 Ampeg V-4

[88mm]

So i recently just bought a 1971 Ampeg V-4 and it works wonderful. Very versatile amp, works well with guitar and bass.

I'm new to having decent gear and i don't know anything about ohms.

The 2x15 Yamaha cab i have says "nominal ohms 4 and minimum ohms 4".

The amp offers a switch for 2, 4 and 8 ohms.

What should i set the ohms at for the amp? There is a sticker that says "2 speakers 4 ohms, 1 speaker 8 ohms" on the back. Are they referring to the amount of speakers or the amount of speaker cabinets?

Thanks for taking the time to read this. I look forwards to hearing back from you guys.

[Leo_Gnardo]

Regardless of any sticker, it looks like your Yamaha cab is 4 ohms, so set your selector on the V4 for 4 ohms. It doesn't hurt to double check: plug a speaker cable into your cab and measure the resistance from sleeve to tip on the cable, that will show you the DC resistance of the collection of speakers in the cab. Typically the DC R is less, sometimes equal to, the impedance. So if you see something like 3.5 ohms, no panic, it's 4 ohms.

And take it easy on those Yamahas, I find Japanese speakers to be a bit fragile. Unless they're unusually heavy-duty you could wreck 'em easily with a V4 at full cry.

[88mm]

Regardless of any sticker, it looks like your Yamaha cab is 4 ohms, so set your selector on the V4 for 4 ohms. It doesn't hurt to double check: plug a speaker cable into your cab and measure the resistance from sleeve to tip on the cable, that will show you the DC resistance of the collection of speakers in the cab. Typically the DC R is less, sometimes equal to, the impedance. So if you see something like 3.5 ohms, no panic, it's 4 ohms.

And take it easy on those Yamahas, I find Japanese speakers to be a bit fragile. Unless they're unusually heavy-duty you could wreck 'em easily with a V4 at full cry.

They are extremely heavy. 1980s Yamaha. Eventually i'll switch to an ampeg cab, but for now this will do.

I picked both of them up for $800.

If the cab is a minimum of 4 ohms couldn't i run 8 through it? I don't quite understand what nominal means.

Thanks for the reply.

[g1]

Speaker impedance changes with frequency. There are many peaks and dips in the impedance curve.
The one you have does not dip below 4 ohm (minimum) and is designed to be approximately 4 ohms on average (nominal).
You will get max. power out of the amp when properly matched to the cab. (4 ohm setting on V4)

[Enzo]

A speaker cab is 4 ohms or 8 ohms impedance. That is a nominal figure, which means that is the impedance when tested the standard way we test speakers.. You don't "run through" other impedances. If you set the amp to 8 ohms for a 4 ohm cab, it just means a mismatch.

[88mm]

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Here's some pictures. Thanks for all the help, i got it worked out!

[g1]

That seems to be the popular spot to add the master volume. Both my V-4's have them added in there.

[88mm]

That seems to be the popular spot to add the master volume. Both my V-4's have them added in there.

So wait, that's a mod that was done on the amp? I had no idea, i thought they were made like that.

[Justin Thomas]

Just noticed the Sig - thanks, g1!

Justin

PS A V4 doesn't need a Master Volume. Pansies...

[88mm]

Just noticed the Sig - thanks, g1!

Justin

PS A V4 doesn't need a Master Volume. Pansies...

Yeah it really doesn't haha. I don't know why that's even there. I don't even use it.

[g1]

If you want real clean and can't get it with hot pickups, use the attenuator switch above the volume pot. The switch is before the first gain stage, the volume is after it.