Radio 3: pre-echo on Liszt loud piano parts

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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by BJG145 »

Liszt's wrists were exceedingly supple
Especially after he'd had a couple

- ECB
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Tim Gillett »

Exalted Wombat wrote: Tue Jul 20, 2021 3:49 pm Pre-echo can happen on vinyl too, when the grooves are cut too close. (Of course, an LP may also inherit print-through from a preceding tape generation.)

Yes and common practice with disc cutting tape masters was to splice plastic leader tape hard up against the start of the programme, meaning any echo pre that splice point had to originate from the cut disc.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by James Perrett »

Tim Gillett wrote: Thu Jul 22, 2021 2:39 pm Yes and common practice with disc cutting tape masters was to splice plastic leader tape hard up against the start of the programme, meaning any echo pre that splice point had to originate from the cut disc.

That practice is now causing real problems if stripy leader tape was used. The stripes attach themselves to the magnetic coating and peel it off the backing - no matter how carefully you try to pull the layers apart.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Hugh Robjohns »

I didn't know that!

I've always used solid colour and clear leaders, but more through luck and availability than anything else.

The Beeb standard was yellow between items on a tape (eg, separate inserts on a news programme reel), red at the end, and often blue at the front of stereo programmes, and green for mono. I can't remember what we used white for... but most edit rooms only had yellow and red in stock anyway, so it was yellow at the front and between items, and red at the end.

Not all leader tapes were made equal -- they often had radically different coefficients of friction compared to the recording tape itself (usually much higher!), and that sometimes caused problems with the machine's speed changing slightly as the leader ran through, resulting in a slur to the start or end of a recorded piece!

I also remember scraping off the red and yellow colour on leaders sometimes to leave a transparent section about two-inches long to trigger the optical end-of-tape sensor and activate the stop button -- an important function in a busy self-op news programme to prevent the tape running on into the next item!

In the commercial world various manufacturers used different colours to differentiate tape types. One standard was white for standard-play, green for long-play and blue for double-play. Again, red always signified the end.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by forumuser840717 »

That's been a problem for years. It's particularly annoying when the stripy leader is used between tracks!

Some tapes and some leader tapes are more prone to it than others and it's really important to check for stripy leaders before baking tapes as that can make adhesion considerably worse (though, in very rare cases, it can also cause it to release).

Similarly, some will release with various solvents ranging from water to different strengths of alcohols or even acetone, while some tapes are destroyed by the solvents so experimentation and note keeping are important.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Tim Gillett »

James Perrett wrote: Thu Jul 22, 2021 2:49 pm
Tim Gillett wrote: Thu Jul 22, 2021 2:39 pm Yes and common practice with disc cutting tape masters was to splice plastic leader tape hard up against the start of the programme, meaning any echo pre that splice point had to originate from the cut disc.

That practice is now causing real problems if stripy leader tape was used. The stripes attach themselves to the magnetic coating and peel it off the backing - no matter how carefully you try to pull the layers apart.

In my experience and reading of the relevent digitisation manuals and guides I've not come across this. Does it occur independently of the tape type and condition of the binder layer?
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by James Perrett »

Tim Gillett wrote: Fri Jul 23, 2021 9:32 am In my experience and reading of the relevent digitisation manuals and guides I've not come across this. Does it occur independently of the tape type and condition of the binder layer?

I first encountered it with old Ampex tapes but have also had problems with 3M 256 and also BASF which were in otherwise good condition and not baked. It sounds like Forumuser 840717 has more experience than I do - I've never tried using any solvents to reduce the adhesion to the ink in the leader.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Tim Gillett »

Thanks and yes good to hear more details from 840717. Tim.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by James Perrett »

Just had another delivery of tapes to transfer - and all the quarter inch tapes have stripy leader everywhere! I think they're all 3M 256 although some of them are in Ampex boxes (but look too dark for Ampex).
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Tim Gillett »

That could be interesting. I've not come across this problem with sticking stripy leader and am not sure what it even looks like. Any chance of a photo or link to one?

Interestingly on the AES list of 3M tapes manufactured, I couldnt find 256 mentioned at all.
https://www.aes.org/aeshc/docs/3mtape/aorprod-cust.pdf
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by James Perrett »

Tim Gillett wrote: Sat Jul 24, 2021 3:48 am Interestingly on the AES list of 3M tapes manufactured, I couldnt find 256 mentioned at all.
https://www.aes.org/aeshc/docs/3mtape/aorprod-cust.pdf

I've just checked the box and it says the tape was made in the UK so maybe the AES list only deals with US made tapes.
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Kwackman »

Tim Gillett wrote: Sat Jul 24, 2021 3:48 amInterestingly on the AES list of 3M tapes manufactured, I couldnt find 256 mentioned at all.

I think, with absolutely no certainty (!), that this was made for the BBC?
Hopefully someone can confirm, or prove me wrong. Again ;)
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Hugh Robjohns »

Tim Gillett wrote: Sat Jul 24, 2021 3:48 am Interestingly on the AES list of 3M tapes manufactured, I couldnt find 256 mentioned at all.

Comes across more as accusative and disparaging than interesting... :think::-|

However, I can easily prove both James and Kwackman absolutely correct.

3M 'Scotch' type-256 wasn't made -- or, AFAIK, made available -- in America and so, probably not surprisingly, it doesn't appear to exist in the American listings.

However, there was a 3M tape factory just north of Swansea in South Wales in a place called Gorseinon that made recording tape for the BBC, amongst others. As it happens, I actually visited that factory in 1981 while at university as Chief Engineer of the university radio station, in a successful attempt to blag a couple of cartons of recording tape for our four studio Revox A77s! I'm afraid I cant remember the tape type I acquired, but it was in orange boxes.

Back in the 70s and 80s the BBC went through many hundreds of thousands of 10.5-inch reels of quarter-inch recording tape every year, so most UK and European tape manufacturers were only too happy to make tape to the BBC's fastidious specifications.

The Beeb needed copious quantities of new tape stock that could be sourced from multiple suppliers but that would work consistently on every machine, everywhere across the entire corporation without the need to continually realign studio tape machines for different types or batches of tape -- something that was obviously impractical on many levels.

Naturally, the BBC's tape spec wasn't entirely bespoke; it was based closely on an existing high quality formulation that several manufacturers either made already or had something very close to and could tweak their formulations a little bit to match.

In reality, of course there were very small differences in the tape formulations from different manufacturers, and possibly between different batches, and so slightly different optimal bias requirements. Consequently, the HF response, in particular, could change slightly and some particularly fussy radio Studio Managers and TV sound supervisors and dubbing mixers expressed preferences for one brand over others... but the differences were always pretty minimal and most never noticed!

Anyway, amongst the various formats and formulations being made at the UK 3M factory in the mid-80s was definitely one called 3M-256, and that version complied with the BBC's then new 'type-200' specification for quarter-inch tape. Here's an image of the box to prove its existence and remove any doubt.
box4.jpg
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Zonal 675 was another type-200 compatible brand, as was Agfa PEM468. There may have been others, but those are the only ones I can remember.

However, I do remember that the type-200 spec came into BBC service in the mid-80s because I spent weeks of work in 1984 or 85 with my engineering colleagues realigning shed loads of tape recorders all across BBCTV and BBC Radio in a very short timespan to facilitate the changeover from the prevailing type-102 tape alignment (if memory serves).

The type-200 spec was introduced to take advantage of the improved characteristics of the newer tape formulations that were appearing in the previous years. One of the most significant improvements was in the higher peak flux capability -- the BBC type-200 spec alignment set peak level (PPM6) to 1000nWb/m.

Type-200 tape remained in use across the BBC right up until tape was phased out as a primary recording medium around late 90s.

Not all of the Beeb's legacy tape machine inventory could be persuaded to run with 1000nWb/m, of course, and many of the older models had to be retired at that time. For comparison, the previous BBC type-102 tape formulation used an alignment of 640nWb/m for peak level (and the type-100 before that was 400nWb/m).

You can read more about the beeb's development of recording tape here:

http://www.orbem.co.uk/tapes/media.htm
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Kwackman »

Hugh Robjohns wrote: Sat Jul 24, 2021 8:05 pmHowever, I can easily prove both James and Kwackman correct.

That's going onto my C.V.

Hugh Robjohns wrote: Sat Jul 24, 2021 8:05 pmZonal 675 was another type-200 compatible brand

I remember that tape, big purple dots on the front of the box.
I can't remember much technical stuff I learnt, but can remember the colour of the box. :headbang:
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Re: Radio 3: pre-echo on Liszt loud piano parts

Post by Hugh Robjohns »

Kwackman wrote: Sat Jul 24, 2021 8:47 pm I remember that tape, big purple dots on the front of the box.

It was rather distinctive.
box6.jpg
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