Stylophone 350S - You have the power!

If you are lucky enough to find a vintage Stylophone 350S up for auction or for sale at a reasonable price and you are tempted to bid on it or buy it, you may be to discouraged to find out that it requires two rather bizarre and costly batteries to operate.  While there are some 350S instruments with AC adapter jacks, most I've seen for sale don't have one. In many cases, the seller will not have even tested the instrument because they don't want to go the trouble of finding the correct batteries. Don't despair! There are a couple of ways to work around this problem.

First, some background information. The Stylophone 350S was designed to be powered by two PP9-size 9 volt batteries. The PP9 is a monstrous thing with dimensions of about 2.72 x 2.52 x 2.01 inches. The PP stands for Power Pack. Today's common 9 volt battery is size PP3. If you were to remove the covering of either the PP9 or the PP3, you would find six 1.5 volt cells tucked inside. PP9 and similar large batteries were once commonly used to power radios. The PP9 is still available, but they tend to be hard to find and rather costly. On eBay, for example, they tend to run in the range of about $10 to $25 USD each. They are more widely available in the UK and Europe than they are in the USA.

The PP9 battery on the left (image courtesy of "Lead holder" at Wikimedia Commons) dwarfs the more widely available PP3 battery on the right. (photo by the author.)

The probable advantage of the PP9 is that it would output higher current (amperage) than a smaller battery. But, the Stylophone 350S will operate on the available power from a couple of today's PP3 batteries.  I learned this by some trial and error when I got my own 350S. I wasn't able to find a pair of PP9 batteries at a reasonable cost, so I bought a couple of PP9 snap connectors and PP3 snap connectors and twisted the wires together to make two battery adapters. The large snap connectors fit over the PP9 battery connectors in the 350S, then the PP3 9 volt batteries snap to the smaller connectors.

WARNING: In my first attempt at testing these adapters, I matched the wire colors and twisted the ends together, connecting black to black and red to red. Within seconds of attaching two PP3 9 volt batteries, they started getting hot! I disconnected them right away and and twisted the wires in the opposite manner, red to black and black to red.  Then everything seemed to work just fine!  In the photo above, the wires are just twisted together. You'll need to properly solder them and cover them with electrical tape or insulated shrink tubing to prevent the wires from shorting out.

The next problem with this solution is that PP3 9 volt batteries are so small, compared to the two relatively cavernous battery compartments of the 350S, that they are going to rattle around inside the instrument and possibly cause damage by shorting out or bouncing off of nearby electrical components. So what I did was carefully move both adapters into one of the two compartments, attached the PP3 batteries, and placed the batteries inside a plastic food storage container that was about the same size as the inside of the compartment.  It was kind of a weird way to fix the problem, but this prevented the batteries from moving freely and causing mayhem, although they still moved around inside the plastic container.  Pavel Frolov, the 350S player in the Russian band Gromyka told me that he solved this problem by cutting a couple of chunks of white polystyrene foam to just the right size and shape to hold each PP3 battery securely.

Recently, the topic of 350S batteries came up in a Facebook discussion.  It inspired me to find a more proper solution that was more similar to using the original PP3 batteries. I found some nifty AA battery holders designed to replace PP7 batteries (another large member of the PP battery family.)

These battery holders fit 6 AA cells and are pre-wired with the snap connectors that will fit the PP9 connectors inside the 350S.  At about $17 USD each, they are not cheap, but they don't require any soldering and they work perfectly for the job. To save some money, you can buy the AA battery holders and the PP9 connectors separately and solder them together yourself.

They still fit rather loosely inside the 350S battery compartments, though. I happened to have some studio acoustic foam handy, so I cut a couple of pieces a little larger than the battery compartment openings and stuffed them inside. The PP9 connector sits under the foam, with the two wires coming around opposite sides of the foam, so there's no chance of any bare metal touching anything it shouldn't.  It all fits snuggly, but still allows the compartment covers to be closed properly, with nothing to rattle around inside the instrument.

As near as I can tell, the performance of the 350S seems to be identical with either of these two replacement battery solutions, but I'm not an electrical engineer, so do your own research and use your best judgement.  Above all, though, power up and play that thing!

(Note: some of the links in this blog post go to eBay. If you follow the links and make purchases, Stylophone Museum will earn a tiny commission. Pay attention to shipping costs. Depending on where you live, some items that may seem like bargains may turn out to be rather costly if being shipped internationally.)