Search found 8 matches

by goodtone4u
Wed Sep 02, 2009 4:29 pm
Forum: Technical Discussion
Topic: VVR adjustment started to introduce some noise
Replies: 5
Views: 2354

VVR Noise

If you are getting voltage control, no need to replace Mosfet. After seeing your reply I checked my amp VVR with a scope on the output of the Mosfet feeding the output transfomer. (Carefully measure using a 0.1uF 600V cap in series with scope probe) Very clean, no noise except when at maximum a litt...
by goodtone4u
Sun Aug 30, 2009 6:03 pm
Forum: Technical Discussion
Topic: VVR adjustment started to introduce some noise
Replies: 5
Views: 2354

Typo on Mosfet connection

Small typo in my last comment the output of the Mosfet is the SOURCE connection going to the output transformer and screens.

I need more coffee!

good luck!
by goodtone4u
Sun Aug 30, 2009 5:39 pm
Forum: Technical Discussion
Topic: VVR adjustment started to introduce some noise
Replies: 5
Views: 2354

VVR Noise

It may be the VVR Mosfet oscillating at high frequencies causing the audible white noise. Most of the VVR circuits do not bypass the pot wiper or power connections with .01 up to 0.1uf 600V caps to ground. Your filter caps may have aged some and may be contributing to this symptom. Ask the VVR desig...
by goodtone4u
Sun Aug 30, 2009 2:34 am
Forum: Technical Discussion
Topic: VVR
Replies: 5
Views: 2908

VVR Source

Go to Hall Amplification for starters. VVR3 is a single Mosfet voltage regulator. Simple cathode biased amps can get by with one Mosfet reg. It gets more complicated if you have a fixed bias amp. http://hallamplification.com/main.html?src=%2F#2,2 The VVR and PPMV are both good to have. You can back ...
by goodtone4u
Tue Aug 25, 2009 2:35 pm
Forum: Technical Discussion
Topic: Making Vox Night Train footswitchable?
Replies: 4
Views: 4402

Re: Making Vox Night Train footswitchable?

Hello, That is the one thing the NT missed is remote footswitch feature. All is possible if you are good at modifying or have a tech to help out. The thick gain is too high to let run wide open. so you will need a second gain pot for Thick mode. (Small front panel hole with a pot adjustable behind f...
by goodtone4u
Sun Aug 23, 2009 4:46 pm
Forum: Technical Discussion
Topic: Vox Night Train Schematic
Replies: 31
Views: 26833

NT15 Amp similar to Park

Cool! That is the closest so far. Lift the feedback loop from OT and place it on the first amp stage cathode. (with appropriate value changes) BTW Some players I have heard using this amp like the thick mode best. Which tosses out the tone stack and gives you more gain. But I still like the Bright/T...
by goodtone4u
Thu Aug 20, 2009 10:57 pm
Forum: Technical Discussion
Topic: Vox Night Train Schematic
Replies: 31
Views: 26833

Vox Night Train Design

Hello everyone, In my investigating the NT amp more, I found a few minor errors in the schematic that was posted last month. Sorry!!! The amp does work fine with prior error but changing the third gain stage plate resistor brings amp up to exact copy. (and voltages are closer) Some of the input part...
by goodtone4u
Tue Jul 28, 2009 1:01 am
Forum: Technical Discussion
Topic: Vox Night Train Schematic
Replies: 31
Views: 26833

Vox Night Train Schematic

:D Had this amp for a week to draw the schematic. Happy building!