Rogers LS3/6 and Leak Stereo 70 combination

[Pharos]

I have two pairs of the Isodynamic headphones, for which I made calf-hide earpads in the mid 80s.

They are a little cheaply made, and veiled, but bought in about '72 so perhaps to be expected, but at the time a breakthrough if you couldn't afford the Pro 4AAs. I also have some spare transducers.

[Martyn Miles]

I have two pairs of the Isodynamic headphones, for which I made calf-hide earpads in the mid 80s.

They are a little cheaply made, and veiled, but bought in about '72 so perhaps to be expected, but at the time a breakthrough if you couldn't afford the Pro 4AAs. I also have some spare transducers.

A friend bought a pair and I quite liked them and wondered if to buy a pair.
In the end I bought a pair of PWB electret headphones in a sale and preferred them.
Do any Forum members recall the PWBs ?

[Barry]

A friend bought a pair and I quite liked them and wondered if to buy a pair.
In the end I bought a pair of PWB electret headphones in a sale and preferred them.
Do any Forum members recall the PWBs ?

Yes they were a very good headphone design - before Peter Belt went off on a tangent with all his pseudo science and dubious audio accessories.

[our_john]

I've got Swisstone woofers in my LS3/6s. My understanding is these were developed by the 'new' Rogers team (after the collapse of the Jim Rogers team) around 1977-78 as they weren't happy with the sound quality of the Dalesfords. Swisstone was the off-the-shelf company they bought at the time due to some issues with the ownership of the Rogers name. They had managed to get hold of the equipment necessary to build these in-house. In essence, the Swisstones are at least as good, if not better, than the original units but far more durable. After all, the new Rogers team comprised developers of the 'original' LS3/6!

For your interest my speakers are currently in for servicing, as shown here...
https://m.youtube.com/watch?v=F8JRlEUJ0Ys

[spendorman]

Very interesting, but the repairer got several things wrong including the type of tweeter and supertweeter. Tweeter is Celestion HF1300, and supertweeter is Celestion HF2000. I don't think KEF had anything to do with this speaker.

The low DC resistance of the speaker is because of the autotransformer.

[walpurgis]

Not sure why he regards them as sealed speakers. They're not!

[spendorman]

Not sure why he regards them as sealed speakers. They're not!

Agreed, possibly he meant that the port has not much effect. As the cabinet size increases, the difference that a port makes decreases. In a very big cabinet a port will not make much difference. I think I remember reading this in a GA Briggs book (G A Briggs of Wharfedale).

[spendorman]

I have never owned genuine LS3/6 bass units, but I think the magnets on the originals are much bigger than on the Swisstones.

[walpurgis]

I think I remember reading this in a GA Briggs book (G A Briggs of Wharfedale).

I read that too, at tech college around 1972 . I have sections of one that was in bits, still very valid.

A port with no tube to extend it has to be smaller to obtain comparable Hemholtz resonance. Tubes tend to be used as they make the port flow more laminar, avoiding the bass 'chuffing' which can be detected on some Rogers and Spendor speakers.

[spendorman]

as late as 72! I was at tech from 1968 to 1975!