Pioneer SE-700 Vintage Headphone Cable Mod and Balancing

The Pioneer SE-700 were the company’s flagship headphones released back in 1974. The driver is an unusual piezo-electric type. I am personally not aware of any other headphone manufacturer that offered this type of driver, but feel free to share in the comments if you know of one. The SE-700, SE-500 and SE-300 all use a similar element. 

An old advert for the SE-700 touting their specs

I’d describe the sound as airy, crisp, and similar to an electrostat with a detail emphasis. Bass quantity is very low, which I believe is typical of this type of driver. The simple metal frame and gimbals look rather elegant, and the overall unit is pretty light. The way it rests on the head is slightly odd compared to modern headphones, but it’s still very usable.

The piezo-electric driver is a very thin piece of metal foil with a frame going around the perimeter, with the positive and negative connections at the bottom. It is covered with bright yellow foam resembling a dish sponge. It is also quite delicate, so even opening the headphone can damage the driver. The unit is sealed shut with rubber cement or a similar adhesive so it must be opened very slowly and carefully to access the inside. 

An image from the user's manual circa 1974

The wire connections for the driver are circled in red below:

If you’re looking to purchase one of these you can keep an eye out on Reverb, eBay or similar platforms. Price for a good example will generally be between $80 and $150. You’ll probably want to replace the wiring including the 3-meter cloth-covered cable, and the vinyl headband and ear pads which will likely be flaking.

My client Steve who sent me the headphones had already replaced the pads and requested the inner wiring be replaced. The existing wiring contacts had been twisted together and covered with heatshrink (see above image), which seemed like an odd manufacturing choice and not an ideal connection. Running single strands from the connection would sound better. You’ll note both sides of the headphone below after the cabling was replaced.

The headphone was reassembled using 3M double-sided tape so it can be more easily opened if needed. Steve will be crafting a calfskin headband for the unit as a replacement for the original vinyl headband, which I feel is the only visual let-down. It appears EricJ from HeadFi created an excellent tutorial back in 2007 on creating a replacement headband which you can find here. Below you'll see the refurbished/modded unit.  

I hope you enjoyed this post on one of the more interesting vintage headphones out there. If you have a headphone that needs a cable upgrade please be sure to visit Zynsonix.com. 

Disclosure: Please remember that using a soldering iron and/or modifying headphones can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a modification posted above and cause physical harm to yourself or your surroundings. 

Rebuilding a Vintage Guild Town Crier Radio

After some searching and scouring, I was able to find a very handsome old radio called the Town Crier. This unit was built by Guild Radio and Television, Inglewood California from the 50s to the 70s in both tube and solid state variants. This particular unit was built in the 70s and it solid state. The radio is fairly heavy and built from wood and metal in the shape of a colonial lantern, it stands roughly 23" tall by 10" wide.

I made sure to procure a functional unit and upon plugging in the unit, the volume adjustment was fairly scratchy sounding and needed some new potentiometers. So I figured I'd tear down the unit and see what could be improved while I was in there. The old pots were CTS VRS-100K-70S that also had a power switch built in that activated when initially turning the knob.

Scratchy old CTS Potentiometer needs to go

Also on the chopping block were a couple of questionable looking capacitors that had began to bubble.

Funky looking ceramic disc doesn't look too reliable

Unfortunately, while CTS is still in business, they no longer build that particular pot. So, I decided to fit brand new Alps mono Blue Velvet pots. These did not have a built in power switch, so a toggle switch was fitted (at twice the specs of the original) that could be mounted on the back of the unit. I opted to replace all easily reachable capacitors with new ones of the same specs or higher. 

Alps Blue Velvet Pots for volume and tone mounted

Secondary View

The driver in the unit was a very low-cost oval paper cone speaker that had begun to flake. This prompted me to remove the unit in the interest of replacing it with another. The spec of the original speaker was 12 ohms, so one could fit 2 six ohm speakers in series or a single 12 ohm speaker. I decided to fit a single 12 ohm circular speaker, and settled on the 5" Audio Galaxy S5N-12 Neodymium full range driver. This unit is likely overkill, but it was unlikely that the Town Crier would be opened up again anytime soon, so might as well go with something nice that would last. 

5" Audio Galaxy S5N-12 Neodymium full range driver

The Audio Galaxy unit barely fit, mostly because of the depth of the magnet. I was hoping to mount a piece of MDF that would act as a baffle for the unit, but there was simply no room to do so.

Audio Galaxy Full Range Driver Mounted

Finally, the power cable was a typical lamp cord that you'd find on just about anything from this period. I opted to use higher quality 16 gauge silver plated copper in teflon wire in a twisted pair configuration which was then covered with black nylon for a vintage look.

The new 16 gauge power cord

Here's some photos of the re-assembled unit below:

Guild Town Crier Front

Guild Town Crier Back

Guild Town Crier Open

Now it's ready for a a few more decades of service :) 

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind.