B3 Burns - 'Low' output

Hi,
i have just purchased a brand new B3 Deluxe.
I started it up and noticed that the output is very very quiet! i have a small practice amp on full volume and it is still very quiet.
I am only using a 12V supply - would this affect the output from the theremin?
THe PSU is also a switched type - selectable from 4 to 12V. I have it set on 12V.

I did buy a non-switched supply but this doesnt work and i cant change the tip polarity (i assume that is why it isnt working).

(Note -I live in England so have a 240V supply.)

I am a little dissapointed with the sound after spending so much. I would appreciate any pointers as to why i am lacking in volume and quality of sound.

(btw - it costs £40 on VAT and Import duty when buying a Burns from USA!!)

If you contact Dan Burns I'm sure he would be more than happy to help you sort out your volume issue.

a) 12V are not enough, the B3 theremins need at least 16V DC input since there is an internal diode in series which eats already 0.6V and then an 78L12 voltage regulator which needs some volts above 12V as regulation headroom.
b) Switched power supplys are not suited for theremins, the switching circuits stray too much RF
c) there is (after the power supply problems are solved) a hole in the bottom of the case through which the volume circuit can be adjusted with a potentiometer.

[i]btw - it costs £40 on VAT and Import duty when buying a Burns from USA!![/i]
You should have asked here before ordering it. There are people who have "channels"...

Thanks Thierry! I will source a new PSU first and then look into the volume isssue.

This looks like it would be a perfect PSU?

http://www.powersuppliesonline.co.uk/product/5-4w-18v-300ma-regulated-linear-plugtop-psu/n89at/default.htm

Seems ok to me.

The only potential problem which I can't foresee is the free-run output voltage. Even stabilized PSUs may have a slightly elevated output voltage when no load is connected. As the B3 draws only a very little current, it behaves like almost no load for the PSU. You should check the free-run output voltage of the PSU with a digital multimeter before connecting it to the B3 and make sure that it does not exceed 28V. If not, you may send me your B3 in for repair... ;-)

its exactlty 18V with no load.

Still dont sound right. It is about 10inches off the floor. I suppose that wont help? Is there a minimum height?

When using the "tuning" knob it flips from lower notes close to arial to high notes when close(normal). At some settings there is a dead-spot with no sound.
What should i be looking for.

[i]Still dont sound right. It is about 10inches off the floor. I suppose that wont help? Is there a minimum height?[/i]

A theremin is normally set up on a mic stand so that you can play it standing while it is at about the same height as your belly. Out of the mic stand, the floor (at min; 2 feet distance) and your body, there should be a clear space with a radius of 2 meters or 6 feet around the theremin.

[i]When using the "tuning" knob it flips from lower notes close to arial to high notes when close(normal). At some settings there is a dead-spot with no sound.[/i]

That is normal (at least for those who understand how a theremin works). Normally you should be standing in front of the theremin at arm length (2 to 2.5ft) from the pitch antenna and at somewhat more than forearm length from the volume loop. Now turn the tuning knob with the left hand until you are in the dead zone. That means that you don't extend your right hand towards the pitch antenna but touch your right shoulder and the theremin makes no sound. After this tuning, pitch should go constantly up when you move your right hand towards the pitch antenna.

[i]What should i be looking for.[/i]
You should first buy Carolina Eyck's theremin method where this setup procedure and also the playing technique is well described.
Second, we should find out why your volume seems too low.The output level of the B3 is about 200mV at low frequencies and goes down to 80mV at high frequencies. This is somewhat weaker than a keyboard or a CD player, but a good amp should have enough headroom. Check first if the problem persists when the theremin is correctly set up with enough free space around. If yes, it may be a grounding or a calibration issue. Which amplifier are you using? Have you checked if the amp and the cables are ok? Is the amplifier grounded? You could also take a picture of your setup, upload it on your webspace or dropbox and post a link here. A German proverb says that one picture says more than thousand words.

[i]I am a little dissapointed with the sound after spending so much.[/i] So much???
If you spend the same amount for a violin, you get cheap chinese crap... The middle class reference theremin is the Moog Etherwave Standard which sells for about 400EUR in Europe. Professional theremins like the Moog Etherwave Pro were initially sold for 1500 to 2000 USD and the prices have still gone up since it is out of production...

The B3 DeLuxe is a fine entry level theremin and one may play music on it. Thomas Grillo has published some videos with it on youtube. But don't expect miracles from it.

It's like the story of the old Jewish man looking at his modest home: "Oy, it's fine but it's not the Ritz"

"I would appreciate any pointers as to why i am lacking in volume...."

As Thierry said, get it up off of the floor.

"I am a little dissapointed with the sound after spending so much. I would appreciate any pointers as to why i am lacking in....quality of sound."

Disappointed with "the quality" in what way?

By itself, the theremin is little more than a tone generator. Much of "the sound" will have to come from YOU.

Of course, the basic tone can also be altered with various audio effects devices.