Quiz

[TubeAmpNut]

Are the initials of the designer L.J.?

 

[B:ASSMASTER]

Man, if I knew what snubbers, PTP, PCB or dingle-hoppers were...I might be able to guess what amp it is.

 

[xpenno]

Nope, it's a PCB amp.

It's not the AFD100 is it??? Lol

 

[Geezerjohn]

They were afraid it might go to 11.

 

[electronpirate]

Nerd Alert!

All your base are belong to us.

 

[ETOLKIEN]

Dear Cliff,
Please model this with the 250K treble pot as was designed.
I love squeals!

 

[Hellbat]

These aren't the squeals you are looking for.

 

[ETOLKIEN]

Are you sure?
3:04

 

[dsimms]

The circuit or layout is unstable and too much treble leads to oscillation.

Exactly.

Cliff - would you please give some more backstory here. I've heard of amps being referred to as unstable in the past, mostly referring to building Trainwreck style amps. Usually that it was difficult to get that circuit under control, took lots of experience and tweaking and just the right cherry picked parts to make it work. What's your take? Do some great amps need to be on the edge of unstable to make their magic? Was it just an easy out for this amp you're referring to when it should have been designed better, or a smart solution?

 

[dr bonkers]

I was working on an amp model today. The amp can be considered moderately "high gain". I couldn't get the treble knob to respond the same as the amp. The model had more treble with the control on 10 than the amp. Finally I opened the amp and poked around and discovered that the amp deviated from the schematic in one small way: the treble pot had a resistor in series with it. So instead of a 250K treble pot it had a 220K pot with a 27K series resistor.

"Why would they do that?", I asked myself. "Why limit the range of the treble control when you can simply not turn the pot all they way up and get the same result?"

Then it dawned on me.

Can you figure out why they did this? Hint: it has to do with tech support.

Will our version of the amp be the safe version or the squeal-o-mania version? I hope it's the latter as I like playing create a crazy thing in the box.

 

[stm113]

Cliff - would you please give some more backstory here. I've heard of amps being referred to as unstable in the past, mostly referring to building Trainwreck style amps. Usually that it was difficult to get that circuit under control, took lots of experience and tweaking and just the right cherry picked parts to make it work. What's your take? Do some great amps need to be on the edge of unstable to make their magic? Was it just an easy out for this amp you're referring to when it should have been designed better, or a smart solution?

I've heard something about the Marshall's Blackmore used (Major maybe) that was unstable in that if you used the wrong pedals it could blow something. Not sure how accurate that is or why.