100W 2nd Generation Hybrid Layout

[jborders5]

This is still a work in progress, but I figured I’d upload the latest revision to see if anyone is interested in the layout. It’s a 100-watt version of the 2nd generation amp with a few later features. The layout has separate masters, PAB, mid boost, footswitch FET, presence control, and a precision power supply. I haven’t built the amp yet, so I’m sure there are a few areas that will need to be tweaked. The mid boost switch yields 507pF with the switch in the down/off position and 2000pF in the up/on position. This keeps the off setting pretty much identical to the stock 510pF. The B+ string is straight from Tony’s layout, so it may need to be adjusted. The FET relay is a standard true bypass configuration and grounds the FET input when not in use. The 10K FET gain is a mini pot mounted in the FET input jack hole. One other option is you could use a mini pot with a push/pull switch and use it as the manual/pedal switch. Currently you’ll need to have the footswitch attached to access the FET circuit. I still need to finish the relay ps, bias/rectifier and a few other things, but 95% of it is there. The layout uses the CE chassis and my boards, but can be easily adapted to other platforms. Thanks for any help error checking.

11/4/10 revision - Full Layout

[M Fowler]

John nice work on the layout.

I have two CE chassis and in one I am using your board set the other will be my own boards non PS type. Both are 100w. The hardest thing has been figuring out which amp to build.

Great boards by the way.

Mark

[dreric]

I have the same problem, two chassis, one board set (thanks John!!) too many choices on amps.

Accutally here as good a place as any to ask:

I have a NOS Marshall 800 (Dagnall) OT. Is there a circuit that likes this OT?

I also have a NOS Fender OT, I think is from the ultra linear "Evil Twin". Does that speak to a circuit?

[Structo]

Yes but is the JCM 800 a 2203 or 2204?
In other words is it a 50 watt or 100 watt OT?

[dreric]

It's a 100 watt!!!!

[Structo]

Gil Ayan told me before his favorite ODS amp has a New Sensor Marshall OT in it.
I believe he was still running 6L6 in it though.

[jborders5]

Full layout has been uploaded.

Does anyone have a better way to run the footswitch using only 5 conductors? This is the only way I see possible that will allow for separate current limiting resistors. It also allows for the other half of the relay ps to feed the main power indicator LED.

[ampdork]

Use the relay coil to limit current to the LED?

[Structo]

On the DIN connector, you want to use the middle connector for the ground.
It can be tied to the case on some sockets.

A better way to denote resistance values is to use the multiplier as the decimal point.
As in 2K2 instead of 2.2K. It can be easy to miss the decimal point.

Why are there two wires from the bias supply to the bias pot?

You should have the hot wire (black) go to the fuse first before the switch.

[jborders5]

Why are there two wires from the bias supply to the bias pot?

You should have the hot wire (black) go to the fuse first before the switch.

The bias supply is the later Dumble method with (2) 47uF caps.

You're right about fusing the hot side of the amp. I was looking at the older layouts where he fused the neutral and not thinking about a safer method.

Thanks.

[Noel Grassy]

Were they used in Rockets too?

[TPL]

I have been looking for the schematic for this layout and I can't seem to find it. Could someone please post the schematic or a link to one for this amp that matches the layout.

Thanks

[Matt J]

Very cool looking!

Any chance AGBamplifiers will be offering boards again soon? I'm interested in buying some of them!

- Matt J.

[M Fowler]

His link still works maybe he is still selling. There is contract email address on his website.

[ToneMerc]

Very cool looking!

Any chance AGBamplifiers will be offering boards again soon? I'm interested in buying some of them!

- Matt J.

He suspended selling boards months ago, but he's told me more than once than he plans on doing another run.

TM