[Hoppy]

I have a pair of pioneer se-700 that have the usual broken cable near the ear-cup connection.
The previous owner has already chopped the plug end 10-15cm shorter to fix an earlier break in the cable. When they did this they replaced the original plug with a large gold plug that looks very out or place with the silver and black headphones.
The pads are worn, headband isn’t as bad but will be replaced.

looking for suggestions/feedback on if they should they be kept as close to original or have mild updates?

1) what to replace the cable with?
The original braided one is noisy when touching clothes or table edge. Currently looking at a black 4-5mm diameter soft silicon 4 core shielded cable. So the wiring to the plug will be ready for balanced by just changing the plug.

2) balanced or not balanced plug?
I have a 6.3mm plug on the way that looks period correct and close to original.

3) should I replace the cable through the headband to match or leave it as original?

4) ear pads so far likely just modern sheepskin one that look ok and ar thick enough to be comfortable. Unless someone knows a original looking one.

I have ordered parts from mouser to build 2 junction boxes.
One is set is as close to the same parts as original, the other is all better parts. So I can potentially make a balanced and non balanced version.
While I don’t have any class D amps, but a balanced version removes the common ground between amp speaker channels in the box so has potential for more compatible amps. I have already confirmed my speaker amp is common ground so either works for now.

 

[Hoppy]

Old topic here has some details on headband repair so added the few difference from this pair.
https://www.head-fi.org/threads/thi...structing-the-pioneer-se-700-56k-slow.234371/

 

[WILLJS]

i would try to keep them as original in appearance with the cable and connector , and i think a upgrade in earpads would be both easier and probably improve the SQ more than balanced anyway

 

[Hoppy]

ordered
soft flexible 3.8mm 4 core shielded cable that should fit through original strain relief.
soft stretch braid not Plastic PET but about 4mm that should give it the original look.
With some heat shrink over the strain relief to braid and clamped into the plug it should hold ok.

removed 2 dead spiders
foam is intact
foil is mint has few tiny fungus marks that should wipe off
have yet to remove the foil from inner cup
found 2 missing tiny metal 1mm wide 2x2mm L fillers missing in left cup.

Also there are tiny 1x5mm shims inside the black plastic pivot points.
So initial assembly takes no pressure or effort as the metal yoke slides into the pivot. Then the shims slide in to lock everything into place.

Stainless steel rings glue seal has 2 gaps where thick tape has been used to hold while glue sets.

The reason for strange connection method of wires at top of cup looks to be from assembly. The ear cup are assembled with drive foam etc and screwed together. Then the headband and cross over wire is fed through later and the cable cannot damage the driver as it is already sealed away. The outer stainless ring is then glued over the top to hide the screws.

foam ear pads are 80mm diameter outside and 36mm inside and taped on. They have the standard ring lip on the back as if they are from a different model that should be pulled over an edge.

Going for 25mm thick sheepskin for now which are three times thicker than original but should help seal and restore some bass. Couldn’t find anything better as most modern 80mm outer pads are 45mm or larger inside.
These are too fat for the headphones to fit back into the original vinyl plastic storage box as total width for cups and pads is 48mm.

Found original spec sheet inside box under the folded cardboard support structure.

 

[Hoppy]

Driver photos added to thread 'The Headphone Driver Pics Thread'
https://www.head-fi.org/threads/the-headphone-driver-pics-thread.202122/post-17799975

 

[Hoppy]

The headband covered in the below topic looks mostly made with plastic sheet and no cardboard seems far easier to take apart.
It took 30 minutes just to separate the underside seam vinyl from the cardboard and rubber. The cardboard top layer tears away as the glue has been absorbed into it. You have to partly cut a line along where the rubber and cardboard meet. After that it’s a slow millimetre by millimetre press rubber down and pull vinyl up for the 10cm where the indented section is. Top two bits in the photo below.

https://www.head-fi.org/threads/thi...structing-the-pioneer-se-700-56k-slow.234371/

Vinyl is around 0.6mm thick and the shape looks to be trimmed once it has been fitted to the headband To match the hand curved alloy end pieces.
Overall the size is 10x19cm.

Original vinyl is polished grain texture so have gloss glove leather on the way. The topic above looks like more soft chamois leather which is more suede like.

Heres all the parts laid out without the main metal straps

 

[Hoppy]

Pro tip for pulling these apart is once you have the stainless ring off.

Do Not fully unscrew the 4 screws. leave them just about falling out.

Then slowly lift one edge, that way you can’t accidentally pull too far and reduce the risk of tearing the foil.
You can hear the foam coming off the foil it’s like a soft static crackling or soda drink bubbles.
Lift a tiny tiny amount like 0.5-1mm and listen, as the sound stops lift a little more.
Take 5 or so seconds to lift it enough to catch on the screws. Then remove the screws and start lifting at the same rate as before.

 

[Hoppy]

Inside of stainless ring.
The white tape is rock solid, like duct tape after a very long time outside.
The black stuff is epoxy like and appears to have been brushed on with a q-tip earbud.
Note the tape is factory as the epoxy glue has two strokes and avoids the area where the tape is to be placed.

not sure if they placed them all the same alignment but both side where rotated about vertical. The left is rotated slightly so the tape isn’t over the strain relief for the main cable.




original cable in background

3 core
red, white black
Right Left Common

3 cotton strings
each 5 strands

outer braid

 

[Hoppy]

April 1975 changes notes say L and R headphone “drivers” have been updated for better sound.
The difference is the 2 small holes in the foil on the newer models.

The diaphragm is exposed to the ear side just behind mesh, so maybe it’s talking about the lack pressure from the foam when the covers are unscrewed. The translation from original Japanese maybe a bit off in the service manual.

I suspected that finger oils and acids would eat away at them over time so didn’t touch the foil. There is a previous post somewhere that did similar and didn’t report any issues. I guess you could measure the capacitance before and after to see if they have degraded.

I have only wiped the foil with 99.95% ethanol via a small ball of tissues wrapped in another tissue, so under as little pressure as possible.
Had to make sure nothing is growing on it since they are a little stale smelling. The spiders couldn’t get foil only into the outer area so that was good.

I’ve had them refitted with foam and cover in place most of the time while sitting waiting for parts to arrive or when not cleaning or drying the outer parts. Mainly as was worried if knocked or dropped the foil would get damaged.

The covers needed a deep soak and dry so they have had maybe 4 hours without the foam clamped. They have some material between the plastic and outer metal mesh trim so needed a very good dry before
The foam was still sitting on them for all but 2 hours where the foam was in the sun to make sure it wasn’t mouldy. Not that I can see anything.

I even gave up on the idea of removing the driver to soak and clean the inner grills. The glue is rock hard after 49 years so didn’t want to risk breaking them. I suspect this is possibly the exposed part of the manual, as it shows pulling the foil assemble out.

Had to soak a folded stack of tissue in ethanol and let the grill sit on that to get the crud out. Then Sellotape to get the rest out. I’d say 95% cleaner overall but far less risk.

 

[Hoppy]

Junction box

case
1” box section aluminium anodise.
6” length
end caps have 6.3mm socket at one end and grommet with banana plug leads to amp.

the two b 8ohm Heatsink resistors with the banana leads between them press hard up the sides so it will dump heat into the case.

mouser parts list
heatshrink and short lengths or wire not included.


a) close to original
b) newer better

a) 100ohm 1% 2watt Metal oxide resistor 660-MOS2CT52R1000F
b) 100ohm 1% 3watt metal film resistor 71-CPF3-100

a) 8ohm 1% 10watt wirewound through hole 10x50mm resistor 71-RS10-8
b) 8ohm 1% 12.5watt wirewound heatsink resistor 71-RH0108R000FE02

ab) banana plug leads cut in half to make 2 pairs of leads
black 510-CT2060-100-0
red 510-CT2060-100-2

ab) 6.3mm socket 490-SJ-63083A

4.4mm socket is on order with matching plug. Will swap over when it arrives.
The 6.3mm will be used for the second version with the more original parts.




6.3mm plug that looks close to original part# 490-SP-6330A

 

[Hoppy]

Junction box done. Well first one that will be made into a balanced version when socket arrives.
clear heat shrink on black wires sit between resistor to press them against side of case.
Wires to socket have loops in case the nut isn’t undone when disassembled.


completed in case
Front of resistors sit about halfway when assembled.
clear heat shrink on one pair of banana plugs to identify which is which.

 

[Hoppy]

Have rubber strip in neoprene and nitrile to see what matches the original material.
Reusing the original material isn’t easy as it is coated in old glue and cardboard.