Feia – cassette restoration case-study

After a few weeks playing with head alignments, audio interfaces, decks, plugins and sanity, I’ve run off a successful “first draft” attempt to restoring these interesting recordings.

About the cassettes themselves…

The cassettes themselves are a little odd – they appear to be using Type-II (CrO2) shells, but I can’t tell from listening or visual inspection whether the formulation on the tape is actually Type-I (Ferric) or Type-II. Both tapes seemed to sound better with Type-I playback EQ, selected in each case by blocking the tape type holes in the shell with judicious use of Scotch-tape.

Noise levels on the tapes were horrendous. Both cassettes seem to have been recorded about 10dB quieter than most commercial tapes given to me in the same batch, and seem to have experienced significant loss of high-frequencies – something that I noticed getting audibly worse with each playback pass despite cleaning and demagnetising the heads before each run. At best I was getting something like 15dB signal-to-noise before noise reduction. Much of this is broadband noise, but there’s also a significant rolling static crackle running on the right channel, which seems to match the rotational speed either of the pinch-roller on the deck, or perhaps the guide capstans inside the tape shell itself.

Playback

Something I’ve always known about the Akai deck I’ve now inherited and restored to working condition is that it’s always played a little fast. While I’ve not been able to fix this at a hardware level (seems to involve fiddling with the motor control circuits – a major stripdown and rebuild I’m not convinced I have the time or confidence to complete without an accident), I have taken an average of how fast the machine is playing by comparing songs from an assortment of pre-recorded commercial cassettes with digital copies from CD or previews on iTunes. From this I discovered that pulling the playback speed down to 95.75% of the sampled audio gives an acceptable match (within 1 second or so across the side of a cassette) to the commercially-available digital versions. This is really easy to do in my audio software as it doesn’t involve convoluted resampling and slicing to keep the original pitch.

Noise reduction

Challenges

A significant HF-boost was required to get the tape sounding anything like a natural recording, which of course brings the noise levels up. I don’t have access to an external Dolby decoder, and the Akai deck used for doing the transfers sounds very strange with Dolby B engaged even on well-produced pre-recorded material that came to me in excellent condition. The Denon deck I have is technically better than the Akai in many ways, but to beat the Akai in sonic terms needs about an hour spent on alignment (per cassette) and the source material needs to be in excellent condition. So I proceeded to transfer the content from the Akai at a known higher running speed, without Dolby decoding, in the hopes of being able to fix this later in software.

Decoding for playback

There is a lot said online about the mechanics of Dolby B, and many people think it’s a simple fixed 10dB shelving HF EQ boost (emphasis) on recording, that is easily dealt with by a simple shelving HF EQ cut (de-emphasis) on playback – or even simply doing nothing with older tapes that have suffered HF loss. Well, without going into detail that might infringe patents and/or copyright, let me tell you that even from listening to the undecoded audio, it really isn’t that simple. What we’re dealing with here is some form of dynamic processing, dependent on both the incoming frequency content AND the incoming levels. Even with its modest highest-available noise reduction, it’s a beastly-clever system when it works, and remarkably effective in many environments, but as with many complex systems it makes a lot of assumptions, open to a lot of factors influencing the quality of the output.

Working up a solution

Having no access to a known-good hardware decoder that could be calibrated to the tape, I set about using a chain of bundled plugins in my Reaper workstation software to mimic the decoding process. Having been through the process, with hindsight I can see why there are so few software decoders for Dolby B on the market, even without considering the patenting issues surrounding it. It’s a tough gig.

For this process, I picked out the best-sounding pre-recorded tape in our collection and aligned the Denon deck to it, listening for most consistent sound, running speed and dolby decoding.  I got a sound off the cheap ferric formulation that came subjectively very close to the same release on CD or vinyl in terms of listening quality – the tape suffering only slightly with additional HF grain, with some through-printing and background noise evident only when listening at high levels on headphones.

I then aligned the Akai to the same tape before sampling (without Dolby B decoding) and correcting for speed. A rip of the CD, and the samples from the Denon, were used as references as I set about creating the software decoding chain – keeping overall levels the same between reference and working tracks to ensure I was comparing like with like.

A day was spent setting up and tweaking the decoder chain before I came out with a chain that gives equivalent subjective performance to what the Denon deck can do with great source material. I tried the same settings on a variety of cassettes, and was able to repeat the results across all of them…

Content, replication and mastering issues?

…until I came to the content of the Feia tapes I was planning to work on!

Once the cassettes were digitised, and playback speed and overall frequency response corrected, each side of the two tapes was given its own stereo channel, so that individual EQ, channel balancing and stereo-width settings could be assigned to each side of the tape, since I noted some differences in each of these areas that were common to each side of each cassette.

While listening to the digitising run, without playback speed correction, I noted a 50Hz hum in the recordings that was common to all sampled media – I tracked this down to issues with signal grounding between the audio interface, the monitor amplifier, and the cassette deck. No amount of tweaking this signal chain could get rid of it, but with the tapes sounding significantly worse with each playback pass the only way forward was to remove the hum using an FIR/FFT plugin. I therefore set one up on each of the stereo channels and sampled a section of the noise (without the content) into each filter and tweaked the removal settings to be more subtle than default – this removed the hum but left the remaining signal (including bass-notes passing through the hum and its harmonic frequencies) intact.

Each stereo channel was then taken out of the master mix and routed to two more stereo channels – one for the noise-reduction decoder and the other for the side-chain trigger telling the decoder what to do.

Listening to the results at this stage was intriguing. Even after tweaking the decoder threshold levels I noted a general improvement in the signal quality, a reduction in noise levels, but still a strange compression artefact that was evident on high frequencies. This got me wondering whether the labelled Dolby B encoding was actually a mistake, and whether Dolby C had been applied by mistake. Cue another day spent mimicking the Dolby C system by tweaking my homebrew decoding system. Nope – compression still there, but the overall spectral effect of decoding Dolby C was having way too much affect on the mid and high frequencies.

So: onto the next likely candidate: dbx noise reduction. I found out more online about how it works and created an encode/decode chain in software, using a ripped CD track as source material.  Applying the decoding stage to the Feia recordings was dynamically a little better in the top-end, but still not right.

Combining the homebrew Dolby B chain, and following it with a little dynamic expansion on the top 12dB of the recording made a useful difference.  Suddenly transients and sibilants sounded more natural, with more “bite” and less splashiness on the decay, particularly at higher frequencies.

Neither tape is sonic perfection itself even after this restoration, but I’ve learned a lot through it, and how have a much better understanding of why cassettes *can* sound great, but generally don’t, especially recordings made on one deck that are played on another.  I now realise that I’d far rather deal with vinyl and pre-digitised content than extracting it from >20-year-old compact cassettes! At some future point, I’ll likely post up some before/after samples so you can judge the results for yourself.

HMV: End of an era?

The news that HMV is calling for administrators is hardly a surprise. As with Comet and Jessops, the question in my mind is “What took so long?”

It’s a cruel irony that I’ve seen some significant improvements to their London Oxford Street and Piccadilly stores in the last few months, especially in vinyl stocks. But that doesn’t really offset the issues I’ve been having with them lately. For incidence – none of the stores seem to have put much effort into being places that anyone would want to spend time in. The constant drone of over-loud pap-Muzak pervaded the entire experience, often distracting from what I wanted to buy. The vinyl sections up until a year ago were badly kept, with old bent/warped stock that was in a perpetual state of disordered chaos. This got better in the last few months at the Piccadilly store, but still wasn’t great.

Even finding CD’s was a chore, at Christmas time in the Westfield Stratford branch I was unable to find anything from the shopping-list of well-known artists we had compiled, except for Susan Boyle’s latest. The cheaply-published and packaged best-of’s offered for remaining artists on the list were hardly good gifts and often didn’t actually contain the ‘best’ of said artists’ output. DVD’s and BluRays were easier to find once I could navigate the crowds, but again I only had a 50% hit-rate. The eye-watering queues at the tills also didn’t help, especially for what should have been quick lunchtime purchases!

For me and my household, despite (always) being on a budget, price doesn’t have to rule the spending decision. Part of the fun of building our music and movie collection has been the voyage of discovery, and the sense of a good shopping experience. If the in-store experience is bad or even just merely indifferent, then that infringes on my perceived quality of the product. If the store doesn’t care about its contents, then why should I, unless I really know something they don’t? Certainly in that case I won’t order online from the same store – likely I won’t order anywhere at all until I find a store that does have it, and cares about it. In short – we tend to buy what we are looking for, or discover on the way – not always the cheapest, and rarely online.

An interesting angle on this was found when I took on the project to upgrade my grandparents’ tape collection to CD. Their collection has a surprising number of quality albums from the 80’s and 90’s, none of which I was able to find on CD in the high-street, HMV included. Given the amount of work involved in converting a number of old tapes to CD, restoring them to “like-new” quality levels associated with CD on the way so that the transition is an improvement as much as a necessity, it is usually far easier and more cost-effective to replace with store-bought new copies. The artists get more royalties, the stores get more sales, and I save myself hundreds of pounds in time, software and electricity doing the conversions myself – that’s a win-win situation! This ‘shopping-list’ style of shopping lends itself best to online retailers now – but even online only about 75% of the content is available, and I’d rather support high-street stores where I can actually physically browse, interact with staff, etc etc. In other areas of life I’ve had fabulous conversations with staff and patrons, even leading to increased sales (“hey, you’re looking for Curved Air, right? i just found some over here!”) and offers of real work. That won’t happen if I buy my music on Amazon!

Another negative experience, and one that pervades all the ‘big’ electronics/media stores I’ve encountered recently, is that there’s no real try-before-you-buy facility, especially on things like headphones and media players. Where such facilities are offered, staff tend to be rushed and pushy, and the range of equipment available for real-world comparison is usually much smaller than that available for sale in-store. Where kit is available for demonstration it’s broken, or priced at such a premium level that I couldn’t afford it even if it were the right thing – many “Beats” or “Bose” headphones for example are easily outperformed by (sometimes significantly) cheaper competition, but with no way to test this there’s no way for the consumer to sort the genuine star-players from the dross.

Seems to me that a lesson being missed here, and one that seems to be in common with Comet, Jessops and HMV, is that there’s a level of basic sales service, and customer experience, that is being missed. Sure, the economic situation isn’t helping. Sure, online sales are taking their toll. But the stores I choose to frequent for such things, especially music, are those like Sister Ray and Music and Video Exchange in Soho, where passion, care and above all, content, are king.

If HMV passes, that leaves small independents a niche. If they (and we as consumers) can exploit that, it could be a very good thing for the music industry as a whole. If they don’t, then physical music purchases will likely become a niche, and consumer electronics will likely follow behind, beyond what the marketeers can tell us all we should be buying next. Sad times. I enjoyed the variety and excitement in these markets in the 80’s and 90’s, and I’ll miss them now they’re all but gone.

Appeal for info: Feia cassettes – Circa 1988-1992

Appeal for info: Feia cassettes - Circa 1988-1992

I have these two cassettes to restore for my grandparents, who have lost their last working cassette-deck to age. The tapes themselves don’t sound to be in great shape, and the claimed Dolby B noise reduction doesn’t seem to play well on any deck I have tried them on. The titles are “Con Amore” and “Canzoni de sempre”.

The tapes shown here were purchased direct from the artist during/after some of her performances in various hotels around Sorrento, during the late 1980’s.

Some questions come to mind:

  • Are these two titles still available for sale, preferably on CD?
  • Anyone else even heard of her?
  • Is she still singing?

UPDATE:  More info from the sleeve notes:

Produced and info by:  P.H. Productions, Marijkestraat 12, 2171 XD, Sassenhiem, The Netherlands / Olanda

I’m getting the impression that this was a small outfit, judging by the lack of a record catalogue number on the cassettes or inlay cards.  This was confirmed by Google Maps, which tells me that the given address is now residential, and looking at the buildings on Streetview suggests this might well have been the case in the 1980’s!