Amanda
"As for an easy drum, a (knackered ?!) Binson drum with a rubber tyre round it a la the Meazzi with recording tape should be pretty near. »I think so…
But and except the level of the « HF bias» you can always « adjust » on each system, and if you imagine you have the same type of record and playback heads, same apparent speed of the drums in front of them, same level of the recording signal, same electronics and so on... does the final « acoustic » (color) result will be the same between using an iron oxyde coating on a SEP wheel and the wound Binson drum ?
It’s a good question !
Now and about the « wear » on the SEP.
An other good question is to know, when the SEP Echomatic was new and came out from the factory, if this iron oxyde was DIRECTLY coated on the aluminum drum ?
If Philips did this job, I think so…
And If yes, Ecca

:
- there was no « cluck » (no possibility, because no « cut » somewhere like with a piece of tape...)
- and sure that if the heads pushed against the drum (and THEY DID…) no doubt that a wear appeared certainly "rapidly".
Now:
In the book « Recording The Beatles » we can discover that an « ambiophonic system » was instalated in the studio One in August 1965.
The author writes :
"Studio one, cavernous though it was, had a reverb time of only 2,4seconds. This was noticeably shorter than the concert hall typically used for classical recording…/…
In an attempt to remedy the situation, Dr Gilbert F.Dutton created a clever system to artificially lengthen the studio's decay time…/…
Dutton sought to simulate this phenomenon (reverberation) by creating a rapid series of multiple echoes or delays through mechanical means.To accomplish this, he turn to a then-new technology known as a "DELAY DRUM » .
Like a larger version of the legendary Binson Echorec, the device made use of a trick and heavy trotting disc (the drum) The outer edge of the disc was coated with ferrite oxyde, the same basic material used to coat recording tape…/… »
so, and for me, this « ambiophonic system in Abbey Road studio One was made on the same principle than the SEP : A « disc » coated with iron oxyde.
It’s the reason why I think that the SEP Wheel was coated (out of the factory) with iron oxyde too. Not with a tape «glue » on the outer edge…
Now and for this Abbey Road «ambiophonic system », and its studio application » :
For avoiding a rapid wear of its iron coated, the author says that the whole of the heads ddid not touch the oxyde...
For that, the heads were «located » (screwed on the frame) with a gap of ONLY TWO MICRONS… (Waouh !!!)
If you see the photo of this « pro " mechanic frame of this system you can understand why it’s was possible to « adjust » this kind of gap… (And the wheel has to be perfectly circular)
But on an SEP…
The answer is : NOT.
And not possible « mechanically » but also for an « physic » reason : The Reluctance.
The reluctance is (for the magnetism) like the resistance in electricity. If the reluctance is too high (here due to the gap in the air between the record head and the iron oxyde) the (possible) recorded magnetic field (on the drum) decreases very quickly.
So if two microns are a sort of limit for this gap (in the air) increase this value and be sure that after that, there is nothing more recorded on the «tape» (!)…
It’s the « simple » reason why on a Binson or a SEP the heads HAVE to touch the edge of the drum… Like these heads touch the tape on an Echomatic Meazzi
Patrice