1009 wrote:soundsofcallado wrote:Has anyone every tried running in full range with the 300 watt section and the 100 watt section? I have 2 GK NEO1x12's I run on the 300 side. Was wondering if I couldn't throw and extra cab on the 100 side and use it for either extra air movement or for a monitor for myself? Would this be a bad deal on the amp?I've put the 300w into a 1x15 and the 100w into a 1x12. I actually prefer full range to bi-amp with that kind of setup.This is pretty close to what I am thinking I may do. Thanks!

Rad!I'm gonna give this a shot; I'm pretty excited about it.

800RB boost footswitch is just a TS jack that shunts the tip to ground, right?

Adam P wrote:800RB boost footswitch is just a TS jack that shunts the tip to ground, right?Yep.

Teacher's Pet wrote:What now?Disconnect the mains transformer secondary from the power supply PCB, insulate the ends (if they're not already in insulated connectors) and switch it on. If the fuse goes then the transformer or mains switch is dud.If it does not go, power off, reconnect the transformer and disconnect the outputs of the power supply from the rest of the amp (according to a schematic I have, this is J2 on the power supply PCB although I know there are different versions of this amp so check to make sure). Switch it on. If the fuse goes there is a problem in the power supply. If not there is a problem somewhere else in the amp. Most likely culprit will be the output section. That will be a ball-ache to diagnose over the internet so if you don't know how to fix it, take it to someone who does.

Teacher's Pet wrote:I need help with a GK 400RB.It blew a fuse. I got a replacement fuse (pdf link) and it blew immediately.I inspected the first blown fuse and it's a 5 amp fuse.Any idea what happened?Any advice on what to do next is greatly appreciated.- RobinTylerSavage wrote:was the second fuse also 5A? If so, open up the amp, look to see if anything is specifically destroyed/burned. if not and you don't know what you're doing, just take it to a tech.something probably failed and shorted.Teacher's Pet wrote:No, the second fuse was 4A.I'll peek inside tonight and report back.I opened this up and I can see a small black mark on one of the leads going to the big transformer.It doesn't look like it exploded in flames or anything, but there is a little black zorch mark at the contact point.What now?

The 800 has two independent power amps: 100w/minimum 8 ohm impedance, and 300w/minimum 4 ohm impedance. The amp has a built-in crossover with a variable crossover point that sends the highs to the 100w power section and the lows to the 300w power section (the Biamp feature that Chris mentioned). The crossover can be defeated however, sending the full-range signal to both power amps.Where this is particularly useful is if you use multiple cabs with different impedances. For example, I use my 800 with an 8-ohm 4x12 and a 4-ohm 2x15. In a traditional setup with the two cabs in parallel, this presents a 2.66-ohm total load, which is lower than many amps want to see. With the 800, I can run the 4x12 with the 100w amp and the 2x15 with the 300w amp. As a bonus, I can balance the levels between the two because the 800 has independent level controls for each amp. If you're only using one cab, or multiple cabs that are the same (a pair of 1x15s, for example) this is not nearly as useful, but it works perfectly for a situation such as mine.

Is there a significant different between the sound & reliability of the 400RB and the 800RB, or am I better off going with whichever I can find cheaper?

Sounds like the simplicity of the 400rb will work best for me, seeing as I will only be using it with a Mesa Diesel 1x15. Plus, they seem to go for cheaper than the 800rb. Thanks all.

400RB and a 2x15 cab can hold it's own with a loud drummer and 2 half stacks easy. Easy.