the Quad ESL uses the clampboard as shown in this picture to protect the treble panel.

these drivers look like the old Beyerdynamic 880DT with the protection circuit. it makes sense in pro-use with musicians in dynamic drivers.

no issues at all, works flawlessly for years

I use the ET1000 with a Stax Amp and it works fine. In fact it is better than the original Beyerdynamic N1000.

Yes, no tensoin before mounting, just without wrinkles but without tension - the construction does the tensioning itself.

Yes I fixed these some time ago. The result is very good. The tension is done with the ridge/rim clamping of the holder and that is what I wanted to tell before. The MS2 are very special to restore.

yes, sorry, I forgot to save

hi Wachara, these are the parts that we discuss: (one picture in the original state, one restored)

I did try it the same way once and was disapointed too - it seems that the clamping of the membrane is important for the sound. and another hint: if the mylar is too thin this mechanism does not work as it should in these phones. I like it best with 6uM Mylar. Atb, Markus

Hi Steve, these ms2's tension the diaphragma, they clamp the diaphragm with a groove and a ridge in the holder. You have to glue it without any tension, just without wrinkles. Atb, Markus

Thanks a lot for your fast answer! I would have to pay 28 Pounds for delivery, so I will wait till I need additional parts and place the order. Atb, Markus

what cable did you intend to use? I ask, because I would need a new cable and did not find anything adaequate in Austria. I have the pins already (taken from xlr plugs) but I need the cable. Markus PS: Koss delivers not to Austria, the Koss extension cable would be my first choice.

Hi, there is at least one other option with the bias on the stator (one stator and 2 diaphragm's) shown in this page: http://www.resmayerling.be/electronica/headphone.html it allows the use of aluminized mylar and seems pretty easy to construct. I would be curious how it works.

Quote: and what does this tell us about response plots? :-)   btw, I would like to take some measurements myself but I miss the necessary equipment.

Quote: there seem to be wide variations in the HP50 series: my HP50A bring the 30Hz with ease.