Vox Night Train Schematic

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tubeswell
Posts: 2337
Joined: Thu Mar 27, 2008 6:42 am
Location: Wellington. NZ

Re: Vox Night Train Schematic

Post by tubeswell »

A couple of potential issues that might be worth looking at with cathodyne PIs are 'gain spike overload' and 'frequency doubling'. Read about these in Ch 7 of Merlin Blencowe's 1st book. The night train sure has a lot of gain before the cathodyne and the grid voltage on those EL84s is relatively small, so methinks that could be something to do with it possibly.
He who dies with the most tubes... wins
ampdoc1
Posts: 669
Joined: Sat Feb 26, 2005 12:42 am
Location: Tulsa, Oklahoma

Re: Vox Night Train Schematic

Post by ampdoc1 »

I think Tubeswell is on the money!! It sounds like someplace in there the signal is getting squashed, then opening back up as the signal dies. But in my quest to try fixes, I've come to the wall on the things I can do on the cheap PCB, and keep the whole thing running.

But there is "happy news!!

I tired several different mods to "improve" the NT. Still a little of that "ghost" noise, but not a deal breaker as it wouldn't be heard within a band setting.

So, I decided to do a little shoot out with it and my Peavey Classic 20, which has very similar circuitry and operation.

I really expected I'd prefer the Peavey, as I've always loved the sound and used it for my "go to" amp in small venues. Both have good clean voicing, but the ODs each had a different color. Both are very good, but the NT has a better EQ'd distortion. Very "thick", with a smoothness that screams "even order harmonics".

a'doc
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