Scaling 1/2 Liverpool - oscillations and other bad noises

[El_Martin]

Hi!

Moved the regulator after the two first caps right before the 1.7 kOhm.
Replaced Zener with 8.2 V, kept 5 Ohm.

There must be some other bug...instable
sometime it works, but not continously
PITA

regulation is very slow, still buzzing noise at approx 250 V

going to replace eyelet board and FET next

@Richie: all black HV caps are 22 uF/450 F&T (most likely produced by F&T) and the blue ones are 33uF/500 V labelled "unicon"

Ciao
Martin

[El_Martin]

Hi!

Resoldered some suspicious points, inserted 100k between pot and ground. Voltage can now be regulated between 30 V and 324 V at first node.

Works fine now!

I just didn't realize, how long it takes to build up some voltages in the filtering chain feeded via 1.7 kOhm ...shoulda known betta

TNX for any help, especially to Dana!

First tests are promising, have to give it some time&testing.

Looks like it suits the Trainwreck approach nicely
Only one additional knob. Does anybody know, if Ken worked on similar techniques? It's so simple

Ciao
Martin

[UR12]

Martin

Glad you got it working! Let us know how the testing goes.

[El_Martin]

Hi!

testing...testing...

Have played the regulated TW a bit

1. seems like the controls have become even more interactive now. Or maybe I didn't notice it before.
2. can be turned down to decent volumes in my living room, w/o totally sacrificing tone&feel of a TW.
3. Pot at 50% gives enough oomph and cleans up well. A bit more compression. Comes handy for a not-so-good player like me
4. turned waaaay down, it is mushy (did expect it)
5. when changing voltages, controls also have to be adjusted to keep same sound&feel. Or put it this way: versatility is increased.
6. heat is currently not an issue - have to test it more

Noticed a ringing in the higher mids, can't say now where it's coming from.
Maybe the speaker. Will experiment.

Have to compare it to a simple resistive load.

Next time I will try some other FET. Like IRFP450 or the insulated case types.
BUZ 80A rDS on: 3-4 Ohms
current production Power FETs have much lower rDS on...

Ciao
Martin

[El_Martin]

double post due to bad server connection.

[Richie]

Although not an express,or wreck amp, this is a demo of The Gabriel voxer 33 using the VVR,and how it works. The rest of the vids i have posted in my listings, are of a band using the Junkyard Wreck express amp..

http://www.youtube.com/user/Greeneyes0v0

[El_Martin]

TNX, Richie!

Gives a nice impression of the VVR.

Ciao
Martin

[rollerwound]

Martin-

How low is the B+ voltage when the sound starts to get mushy?

[El_Martin]

Hi rollerwound!

I have to do further testing. Changing loudspeakers etc.

Ciao
Martin