Why are most tube based pedals running on low voltage.

[Burstbucker]

I just picked up a used Tube Works, Real Tube Overdrive pedal and I must say that I really like the sound, very crunchy vintage tube tone IMHO.

When I first looked at it, I noticed that it's got a 120volt power cord rather than the more common 9-15volt jack.  So I wrongly assumed that the tube was running on a high voltage rather than the "starved plate" scheme found on most tube Overdrive pedals but when I opened it up I saw that there's actually a 120/12volt stepdown transformer in there and the tube is powered with 12 volts AC.  That kind of bummed me out even though the pedal sounds great, so I guess I shouldn't worry about it..

I have a Tonebone Classic and it runs on 15volts, and a Mesa Boogie V-Twin pedal that I had before that was the same deal.  Why is it that so many companies design their tube pedals with a low voltage?  Is it cheaper to build or could it be a safety issue?

[cd]

Is it cheaper to build

Bingo!  Make a cheap pedal with a tube in it for marketing purposes, sell the hell out of it and make $$$.

[The Tone God]

Cost is one issue. Its also easier. You can run everything off of the heater supply. The heaters are probably the biggest thing to contend with power wise when using tubes in pedals. There are other reasons to make low voltage tube pedals.

Safety. Thats probably the biggest thing with production music equipment. In order to sell something with high voltage you have to meet a set of fairly strict (or in the case of the CSA REALLY strict) safety requirements.  You need to get safety approval which cost money and time. If you plan to sell to other countries you need their approval as well. It all becomes a big headach so its easier to go with a low voltage option.

Most effects that have tubes in them, particularly if they make an effort to show off the tube like a window in the case, are just there to make people go "Oooo...look ma! It has tubes." and think that its got to sound good if it has tubes. Everything with tubes sounds great right ! :roll: (I know, I know. Here comes Puretube).

Andrew

[sir_modulus]

I completely back the above post. Here in Canada, you won't believe how strict CSA is on things that go above and beyond 200V or so. Besides, when you start building HV tube pedals you run into a lot of other unwanted issues, such as hum, feedback, size, heat (all this makes a lot of heat, you know), cost, weight, and of course safety.

Tubes have a lot of mojo attached to them. They do make sound better......when used properly. There are such things as bad tube amps, as there are bad transistor amps. Tone is often very subjective to the listener too. I didn't like my chandler tube driver at all, and thought that the stock dist. channel on my Marshall SS (this thing is nice, got JRC4558D's in it...and they actually do sound nice (with LED's and other diodes in this case)) was so much better.

Hope that helps, Cheers!

Nish

[octafish]

It wouldn't have anything to do with reduced headroom would it? I'm not that knowledgable about tubes and amp design but wouldn't you do everything you could to push them into breakup? (Or is the pedal you mentioned a clean booster type overdrive?) Doesn't reducing the voltage reduce the headroom?

[Paul Marossy]

Operating a tube circuit like that does two things: Reduce the headroom somewhat, and forces the tube to operate in its non-linear region. These factors are part of what gives the Tube Driver and similar circuits their rather unique sound.

[boogielicious]

I built the Allen Solemate a while back.  He ran the tubes at ~150vdc on the plates using a transformer (he sells the tranny on his site, www.allenamps.com).  It's not that complicated, but the kit was $200.  It was nice, but had too much gain for me.  Fun project though.

Scott

[Paul Marossy]

Hey, is that Allen Solemate supposed to be an offering to compete with the Matchless Hot Box? I saw that thing once on the Allen Amps website, but I didn't pay that much attention to it.

Anyhow, from the B+ voltage being used, it almost sounds like he is using a 1:1 power transformer with a diode rectifier section...

[william]

I don't want to be a stickler for details, but the Mesa V-Twin runs on hi-voltage.  There is a setup transformer to take the 12v back up to 240.

[object88]

I don't want to be a stickler for details, but the Mesa V-Twin runs on hi-voltage.  There is a setup transformer to take the 12v back up to 240.

Eh?  It goes 120->12->240?  Why not have two parallel TXs, one to go 120->240 for the tubes, and one to go 120->12 (for whatever else is in there)?  Perhaps sourcing a 120->240 TX is difficult?

[Peter Snowberg]

If you feed the pedal with 12VAC, you can buy an AC adapter that has already passed regulatory approval. You can also use the pedal in different countries by simply using a different adapter.

Besides.... 240V:12V transformers are more common than 120V:240V units.

[smashinator]

Not to hijack the thread, but where would a fella look for info about getting the "safety approval" taken care of?

[Peter Snowberg]

It's beyond unrealistic for individuals to get regulatory approvals, but the first stops for North America are...

http://www.ul.com/
http://www.csa-international.org/Default.asp?language=english

Every country has it's own process and standards.

[william]

So what are the legal reprucusions for small builders that are making small runs.  I'f I start making tube amps for sale (something I am seriously considering) should I get safty approval?

[The Tone God]

So what are the legal reprucusions for small builders that are making small runs.  I'f I start making tube amps for sale (something I am seriously considering)

If something goes wrong you can get your ass sued off for selling unapproved equipment. Also if the goverment finds out that your sell equipment without approval they can go after you.

should I get safty approval?

Yes.

Andrew

[Peter Snowberg]

In some states and many countries it is illegal to sell anything that plugs into the mains that doesn't have regulatory approval.

The user of an unapproved amp is in most cases invalidating their homeowner's insurance! :shock:

[Paul Marossy]

The user of an unapproved amp is in most cases invalidating their homeowner's insurance!

I did not know this. What would be the scenario - something like "Uh, my DIY amp caught on fire and I didn't have a fire extinguisher handy and my house burned down while I was trying to find my garden hose" or would it be something else? Maybe "my guitar buddy came over and turned my DIY amp on and he got shocked to death"?

[george]

getting back on topic ....

IMHO valve overdrives don't NEED to be high voltage to sound good ....

... just ask David Gilmour and Eric Johnson, who have both used the Chandler Tube Driver which runs a valve with approx 30V plate voltage (the original 4 knob one that is).

I've built the Shaka Tube which is very similar to the Tube Driver.  To my ears I wouldn't get a lot more tone quality from valves running at 150V+, certainly not enough to warrant the extra expense (and danger) ...

[ninoman123]

While we are on topic of tube distortions...

I was thinking about building one. I'd like low voltage if possible because well...I'm not all that experienced and I'm prone to making mistakes.  Where could I find a schematic for the Chandler Tube Driver? Ive seen the Shaka Tube schematic but I would like to see the Chandler Tube Driver to compare.

[barret77]

What about Real McTube?

I have not built it, but I plan to. Has anyone did it?