Vox Night Train Schematic

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Bplus
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Re: Vox Night Train Schematic

Post by Bplus »

The Night Train also reminds me of this old Park amp, at least layout-wise.
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goodtone4u
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NT15 Amp similar to Park

Post by goodtone4u »

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/Tone controls for Strat cleans.

Joy!
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hbamp
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Re: Vox Night Train Schematic

Post by hbamp »

loverocker wrote:
hbamp wrote: Only Mastervolume tandem pot schould be between the caps.
That's only required for a fixed bias amp. The NT is cathode biased and should be able to work with a simpler arrangement (simpler even than the one drawn out in the OP's schematic). I have a Vox NT here and I will get around to opening it up soon to check guts against this schematic.
IMO it sounds better that way. Maybe just taste.
Dutch hand build amps
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dorrisant
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Re: Vox Night Train Schematic

Post by dorrisant »

Does anyone have a schematic for the lil night train... The one with the 12au7 output tube?

Tony
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sepulchre
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Re: Vox Night Train Schematic

Post by sepulchre »

dorrisant wrote:Does anyone have a schematic for the lil night train... The one with the 12au7 output tube?

Tony
There's a discussion of it over at Hoffman Amps.

http://www.el34world.com/Forum/index.php?topic=10087.0

You might find a lead there.
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randalp3000
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Re: Vox Night Train Schematic

Post by randalp3000 »

You can get one of these right now for the price of a pedal.

Sweetwater has them on sale for $249 and there's a $100 mail in rebate for a total of $149.00 for a night train

here's some more info
http://www.thegearpage.net/board/showth ... ?t=1164654
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Travst
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Re: Vox Night Train Schematic

Post by Travst »

I grabbed one for the same deal. Thanks for the schematic, that will be a big help for the future!
John

I need more practice, not more gear.
ampdoc1
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Re: Vox Night Train Schematic

Post by ampdoc1 »

Additional Info:

I looked up this amp on the internet, and it appears this is a frequent problem. I pulled the covers off today and tested the tubes. Both the preamp tubes and one of the power tubes showed a lot of grid leakage, All tubes looked new,..Sovtek brand.

But after retubing the amp, there was little difference in the sound. Opening up the amp was simple and I love the tube cage (wish I could figure out how to make something like this for other amps).

Looking at the PCB, the solder has migrated up thru the board on a few of the components, but mostly not. Poor solder joints might explain why this is a semi-frequent problem, but not universal.

Any thoughts?

-------------------------------------------------------------------

I purchased one of these at Sweetwater. Free shipping, and 2 day delivery.

But, the box had been previously opened, as I noticed some SW flyers inside, and a SW tape reclosing the box.

I assumed that this may have been a store model, or an amp that had been returned, repaired and put back into inventory,...not that I really cared at this pricepoint.

HOWEVER, the amp has a problem! As the signal dies,..a ripping distortion is heard. To verify the problem, I used 3 guitars, 2 guitar cables and 2 speaker cables, with no change. I notified my salesperson at SW, but have received no reply re the problem, although he has sent several emails brochures of other products.

Anyone here familiar with Vox, who might have an idea of the problem? I'm thinking bad PS caps, but I haven't been inside yet.

a'doc1
Matt D
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Re: Vox Night Train Schematic

Post by Matt D »

The ripping paper distortion on the decay of the note seems to be a "feature" of this amp. On mine it seems to only be noticeable when the preamp gain is above 10 o'clock. It is actually kind of a cool effect for a low-fi trashy guitar tone.

My solution in bright mode is to keep the preamp knob as low as possible and turn up the master. Playing at band rehearsal volume with a 1x12 Greenback cab I get just the right ratio of power tube distortion to volume with the preamp at 9:00 and the master at 3:00. That is really the only usable sound for me from this amp, but it is a good sound. I didn't really expect much out of the triode mode, the thick mode, or the preamp distortion anyway. I wish they had made a "Night Train Lite!"

Swapping tubes made a difference for sure. I put an Eico branded Mullard in V1, a Raytheon in V2 and switched the power tubes for JJ's.
ampdoc1
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Re: Vox Night Train Schematic

Post by ampdoc1 »

My 15W NT does this at all levels, clean or OD mode. I've heard several good clips on the internet, and I don't hear this problem with them. And, I can't believe that Vox designed, marketed and sold an amp with this kind of problem. I'm convinced there is a manufacturing problem.

I'm going to try re-soldering all the connections to the PCB and see if that makes a difference. While I'm not out too much money (once I get the rebate), I'd like to get this thing working correctly. I think the basic sounds are good,..very comparable to the Peavey Classic 15, one of my favorite amps.
puke hat roy
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Re: Vox Night Train Schematic

Post by puke hat roy »

There is a very good and lengthy discussion with a possible solution over on TGP. I have the same note decay fizz at 9-10 volume and gain at 12-2 in bright mode on pentode, but not so much on the triode. It appears there is a problem with the grid stoppers.
ampdoc1
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Re: Vox Night Train Schematic

Post by ampdoc1 »

After searching for hours the last couple of weeks for info on the problem with this amp, I found a Forum that had been discussing this very amp for the last year.

http://music-electronics-forum.com/forum.php

I'd never seen this site, but it looks like there is a lot going on there.

Happily, one of the guys there figured it out. Basically, the amp needed larger grid stoppers on all the preamp/PI input grids. Don't understand why EVERY customer didn't complain about this!


If you're interested go to the Guitar Amps/Mods & Tweaks section, and click the fixes/mods. The last page (of 7) describes all the changes one member made to bring his amp up to snuff.

a'doc1
surfsup
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Re: Vox Night Train Schematic

Post by surfsup »

ampdoc1
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Re: Vox Night Train Schematic

Post by ampdoc1 »

I made the changes that were given on MEF. Definitely much better,...the "ripping" is about 90% gone. I'm good with that, in that the member who suggested these changes had also made numerous other changes (PS and caps replacement) before he added the grid stoppers.

For me, this is good enough now.

I still wonder though, as the NT15 had only minor changes during it's life, how could most users have settled for the sound of the amp as it was. Perhaps, as the amp was relatively inexpensive, most of the users were not cognizant of what a good amp should sound like.

But, I'd advise anyone who wants a good small amp with the same basic circuitry, to find a Peavey Classic 20,..a much better amp all around.
ampdoc1
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Re: Vox Night Train Schematic

Post by ampdoc1 »

Well, good enough wasn't enough. Used my scope and found some problems... strange ghosting distortion of the signal between the pre and PI. While checking the OT to see if it was bad, I noticed almost all of the spade lugs to the board were loose. Crimping them down helped enormously. The amp now sounds great in both modes, with very little of the original fading distortion.

I also added an internal pot to scale the OD signal down to a level just above the clean. Clean is good, and the ODl gives great second harmonics/sustain/feedback.

Only gripe here,...cheap foreign parts and shoddy workmanship. At the price I gave, I don't mind having to work on it. But I'da screamed like a banshee if I had paid the original retail for this half-assed design.
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