I hate cars

This has been happening with this amp with 3 different subs in 6 different configurations. The weird thing is it will pound out the super low 20-40hz stuff all day long at very high levels. Throw some 60-90hz material through it and it shuts off at high volumes.

I could maybe understand it when I had a pair of 12W6s sealed that required a ton of power but this IB setup requires very, very little power and the gain is maybe 1/4 of the way up.

Amp is an Infinity Beta Digital 300. Old amp I know but I bought it NIB 3 years ago.

Can't wait to get the 900/5 but I would like to figure this one out.

jda123

What ohm load are you running to the subs? Is that a full range, or sub class amp? The ohm load changes with frequency and perhaps the upper frequency is jacking it up... but this is not really all that likely (maybe 1%).

Even at 1/4 gain, you can still be at max power of the amp depending on the input signal (1v in might need 100% gain and 5v in might only need 1/4... or something). If you have a large capacitor equal to the load of your amp, and a o'scope, you can see what wattage it is putting out. Without this, you have no idea how much wattage it is actually putting out... just guesses.

Also, does it do it cold, or just after it heats up?

I hate cars

This is close to the answers I'm getting over at DIYMA. Some think the impedence of the sub dips too low in the upper frequencies and causes the amp to shut down. Now that I think about it, this did not happen with the Tempest X, only the JLs and the AEs. There's very little power going to the subs right now. Input signal is 2v at full tilt. Xmax occurs around 190w at 20hz so I know I'm not pushing more than that.

It will do it when stone cold but it's more likely to do it when it's hot. I'll have the 900/5 soon but I'm still very interested in what's going on. I ran the old JL 6 channel to the W6s years ago and did not have the same problem. I'm guessing it's the amp.

From what I remember, this old thing is one of the first automotive class Ds. I've read that it will only play up to 300hz but never tested it.

The other problem I have and have had since I had the very basic setup with 2 W6s sealed and the amp running off of a LOC. Sometimes the bass was very rich and detailed. Sometimes it's just not there. The problem has continued with the AEs but nowhere near as bad. The more I sit here writing, the more I'm convincing myself I have an amp problem.

Almost forgot, I'm running a 2 ohm load to the amp. Maybe I could try an 8 ohm load and see if that changes anything.

jda123

Try it at 8. It might even sound better too, if the amp can give you enough juice.

People forget that these ohm loads are nominal and not static and they change with frequency. Have you tested the AE's coil sitting (they are hard to test under load)? They could be 3.3 and still be called 4. ...and a pair of those would drive your amp to the edge of sanity.

I hate cars

You're probably on to something. I did not have a problem with the W6s when running 8ohms but I did at 2 ohms. I'll give them a shot right now at 8ohms. I have plenty juice available so that won't be an issue.