Figuring out what year amp I have

[urameshi]

Hello,

I purchased a Sunn Concert Lead today. This is the first Sunn amp I've owned and I was wondering if it was possible to figure out the year this one was made based on its serial number. Also, how many ohms are these heads? Any and all information would be much appreciated; thank you.

[Chuck H]

I'm sorry but I don't know how to figure the year. Since it's a transistor amp it's not one of the collectible models. So knowing the year is really only relative to finding an accurate schematic and such. Unless you plan to work on the amp I wouldn't worry about it.

I've read that the amp can deliver about 200W into 4 ohms. Don't use a load smaller than 4 ohms and you'll be fine. Higher loads are OK too, but will produce less power (less than 200W is very relative). I doubt you'll want for more watts even if you use a 16 ohm load.

[urameshi]

Oh, okay. Thank you for the information.

I'm sorry if this is an amateur question but when you say a "smaller load", is 2 ohms a smaller load than 4 ohms or larger? I've always just matched the head and cab exactly (ie. 8 ohms > 8 ohms) so this is something I've never been exactly sure about. Since ohms measure the impedance, a lower amount of ohms means that more current travels through, right? So that means 2 ohms is larger than 4? Or am I just completely wrong about this? Thank you!

[Chuck H]

When I said small I was speaking (writing) strictly numerically. No operational theory involved. So... 2 is smaller than 4. Therefor a 2 ohm load is incorrect. I'll explain a little...

WRT solid state amps, there is a maximum current they can deliver at the voltage they produce. They will try to produce this voltage no matter what load they are plugged into. Therefor, if you plug your amp into a 2 ohm load it will do it's best to produce it's full AC voltage into that load and overdissapate. Burning up your outputs. A higher load (8 ohms or 16 ohms) will actually demand LESS current than the amp can produce and is therefor safe. But since the voltage remains the same the actual watts into and 8 ohm or 16 ohm load will be less than a 4 ohm load. Which I've read is safe for your amp. So maximum power is a 4 ohm load. Transistor amps do not work the same as tube amps and the rules are different.

[urameshi]

Okay, thank you very much for explaining all of that, it definitely helped me understand more. I appreciate you taking the time to help!

[Enzo]

Tube amps have a transforme output with "taps" at various impedances, and there you match the amp impedance tap to the speaker impedance.

Solid state amps don;t have that. The lower the impedance value, the more it demands from the amp. 2 ohms means the am will have to provide twice the current compared to a 4 ohm load. SO 2 ohms is the heaviest load and 16 ohms is a much li9ghter load. SS amps have a minimum load rating. Maybe 200 watts at 4 ohms. In that case 4 ohms is as low as you go, don;t connect a 2 ohm load. However, higher impedances are fine. a 200 watt at 4 ohm amp will be happy as a clam with 8 ohms or 16 ohms, it will work less hard even. SO ther is no matching the speaker to the amp, there is only not overloading the amp with too low a speaker impedance.

For someone not familiar with the concepts behind it, it can be very confusing to use terms like "larger" "minimum impedance" and so on. The lower the impedance, ie the smaller the number of ohms, the heavier the load on the amp. SO it can be confusing to say a smaller load to someone not sure if smaller load means smaller impedance number or smaller in terms of work the amp must do. When someone comes up with a clear unambiguous term for this that won;t confuse anyone, I'll be all for it.

[rjb]

For someone not familiar with the concepts behind it, it can be very confusing to use terms like "larger" "minimum impedance" and so on. The lower the impedance, ie the smaller the number of ohms, the heavier the load on the amp. SO it can be confusing to say a smaller load to someone not sure if smaller load means smaller impedance number or smaller in terms of work the amp must do. When someone comes up with a clear unambiguous term for this that won;t confuse anyone, I'll be all for it.

I use the terms "heavier" or "lighter" load. Less ambiguous if the someone knows Ohm's Law.