DIY Valvulator?

[Michael P.]

http://www.vhtamp.com/product-news/valvulator1.html

Has anyone built something similar to this? I played through one recently and loved it - it really smoothed out the sound of all my effects going into an amp. It's not very expensive to purchase, but I've been wanting to get into making some tube projects and this seems like it might be a good introduction before moving on to reverbs, amps, etc. Is there a schematic out there for it?

[bwanasonic]

Well it's not tube, and it doesn't double as power supply, but you might want to try the AMZ Mosfet boost for it's input/output impedance properties. It should achieve a similar improvement in sound. The valvulator is one of those items I would be more inclined to buy, at least until I get a LOT more experience with construction techniques. They show up on ebay for $125-$150 regularly.

Kerry M

[Michael P.]

Actually, I'd been planning on building one of AMZ's buffers for that very reason, but after trying the Valvulator recently, I'm really leaning towards a tube unit. And, as a first tube project, I figured it probably wouldn't be much more difficult, if at all, than one of the various tube overdrives, and certainly easier than a reverb or amp.

[lovekraft0]

The V1 does not boost the signal or change the tonal character. This is important because you do not want to color the original guitar sound or artificially overload your effects devices, which may cause harsh distortion or unnatural sounding compression.

So why bother using a tube, and having to build an expensive high voltage power supply? Jack's buffer will run from batteries, doesn't generate any serious heat, and ought to be seriously superior in linearity! If I were going to the trouble to do a tube build, I'd at least make something that sounds like it has a tube in it - but that's just me.  

[bwanasonic]

So why bother using a tube, and having to build an expensive high voltage power supply?

I never tried the Valvulator, but I did consider buying one a while back. I ended up with two Visual Sound *one-spots* and Jack's Mosfet boost. Not quite the cool factor of the Valvulator though. As to why a tube: which is cooler- "mine is more linear", or "mine has a tube in it"? Most musicians I know would pick the one with the tube every time. I think VHT is marketing to musicians, not EEs.

Kerry M

[Michael P.]

"The V1 does not boost the signal or change the tonal character. This is important because you do not want to color the original guitar sound or artificially overload your effects devices, which may cause harsh distortion or unnatural sounding compression."

Well, in the context in which I tried it out - before a PodXT - it definitely colored the sound, albeit in a postive, subtle way. It did sound more, well, "tubey." So I'd say that VHT's copy, though correct about distortion and compression, is in error.  And, I still think a device like this would be a good intro to tube project building.

About the Mosfet boost: does it "boost?" I don't want boost per se, I want buffering.

[bwanasonic]

About the Mosfet boost: does it "boost?" I don't want boost per se, I want buffering.

Both. You can configure it as a unity gain buffer. See Jack's article at www.muzique.com .

Kerry M

[dosmun]

http://www.muzique.com/lab/superbuff.htm

[lovekraft0]

Here's a simple 12AU7 White cathode follower that I breadboarded up from spare parts a while back - it was pretty much transparent, and it'll drive a line level load. It didn't sound tubey at all (at least to me - in fact, it didn't sound like anything, so I didn't pursue it further), but it might do what you want. All the caps were 250V and all resistors 1/2 watt metal film.

Click on the thumbnail for a full size schematic.
All standard tube build disclaimers apply - heater wiring is assumed and not pictured (I used 6 volts), the necessary power supply develops potentially lethal voltages, YMMV, no guarantees that this circuit will be of any use to anybody, etc.!  

I'm sure this circuit could be optimized further, if one of you veteran tube builders wants to tweak it - like I said, I lost interest.

[Michael P.]

Yea, "tubey" is a crummy word - I felt stupid using it - but it's all I could come up with to describe the effect it had on the PodXT. Perhaps any
buffer would have the same effect, I really can't say.

Thanks lovekraft0, this is a good start. If any tube experts have any suggestions, I'm all ears.