what to scale on a 5e3 with VVR?

[tanyet]

Just wanted to know people's opinions on whether to scale the whole amp or just the power section of a 5e3. I've done several searches but there's not a ton of info on 5e3 installs of vvr's. What are the pluses and minuses of each?

I know with scaling just the power section I'll have to have a ppimv installed. From a layman's perspective that seems like defeating the purpose.

Also, any opinions on location of the unit? Any special things about a 5e3 install someone should know?


I'm certainly not capable of doing any of this but I need to know what to tell my tech.

Thanks

[ThermionicScott]

There's nothing that says you need to install a PPIMV at all. If you put power scaling on just the output section, it'll break up at a lower volume, just like you want!

Now, if you power scale the whole amp, the preamp stages will distort sooner, which you may or may not want. I guess my inclination would be to apply the power scaling to the whole thing.

- Scott

[Gee]

If you scale just the power section with a VVR then you must uses an MV.

I have 2 Deluxe's, one a 5E3 and a 5D3/Gibson GA-6 hybrid, and both have VVR's that scale the whole amp. I am very very pleased with the VVR scaling the whole amp.

If you are using a 5E3 chassis then there is plenty of room between the PT and circuit board to mount a VVR circuit. The MOSFET should be bolted to the chassis (using a thermal insulator). I found that the best place for the VVR control is to replace the Standby Switch with a 3 way Off-Standby-On switch and then use the old now unused On/Off switch hole for the VVR control. You could just use the VVR control as a "Standby" by switching on with the VVR turned down.

Best to get a kit from ur12 (Dana) who developed the VVR circuit - search 18watt or ppwatt for lots of VVR info.

[muchxs]

Just buy a Maven Peel Zeeta if you can track one down. It's a tweed Deluxe circuit with the most sophisticated "power scaling" available.

[Gee]

Originally Posted by muchxs

Just buy a Maven Peel Zeeta if you can track one down. It's a tweed Deluxe circuit with the most sophisticated "power scaling" available.

I had a quick look at the Maven Peel site. They have an interesting take on their Tweed Deluxe by using EL84's - easy to overlook power tube choice.

"Vintage tube amps typically produce about 20% sag, while more modern transistor amps produce about 2% sag. Modern attempts to produce sag, such as adding solid state or tube rectifiers, yield sag rates of approximately 5% and 15%, respectively."

I wasn't aware that adding a tube rectifier was a modern attempt to produce sag. They certainly have some unusual ideas.

[tanyet]

Thanks for the reply guys. I bought dana's circuit and it came with detailed instructions but I was wondering what people had done with their 5e3's. It looks like scaling the whole amp is the way to go. I'll take Gee's suggestion about placement.

I had heard that there might be some noise issues at low volumes scaling the whole amp but I'll try it and see.

Thanks again. It's nice to have a resource like this place to turn to.