Multitrack Cassette Tape Transfer to DP - Need Help/Advice

[Babz]

Here is my oddball problem…

I have some old tracks that I recorded back in the day on a Yamaha MT3X 4-track cassette multitrack. The tracks were recorded at double the normal cassette speed, and with DBX noise reduction. I no longer have the 4-track machine. I do have a standard two track cassette player. It has a pitch adjustment for fine-tuning speed, but cannot do double speed.

Would it be possible to playback the tracks at the slower speed (normal cassette speed) and record them into DP and then somehow speed them up to the correct speed/pitch?

I imagine this would not be possible without serious artifacts. Has anyone ever attempted something like this? Is there some plugin or other software that might work best for this?

What about the DBX? Is there some sort of like DBX noise reduction emulation plugin? (This is less of an issue than the main problem of just getting the tracks to the right speed.)

Here's another thought, a long shot … Is there anyone out there who still has a double-speed cassette multitrack (preferably Yamaha) that might be willing to transfer the tracks for me?

Thanks in advance for any ideas or suggestions….

Best,
Babz

[magicd]

Speeding the tracks up is the easy part. The difficult part would getting two two-track passes in synch.

Since the tape is slowed down, that means pitch, tempo, and formants are cut in half. You don't want to do any DSP processing to speed the recording back up, because you want all three elements to be speeded up together. So if you record the original pass at 44.1, you then want to change the sample rate flag on the audio to 88.2, and then play it back at that sample rate. Theoretically you'll get exactly the right speed, pitch, and formants.

However, since you have four track recordings and a two track deck, getting all four tracks over and in synch will be a real challenge. If you flip the cassette over, the second set of tracks will play on your two track machine, but they'll play backwards. Ok, so you can reverse that audio and then double it's sample rate. What you then hope is that the deck has constant enough speed that the two passes will stay lined up.

As far as the Dolby goes, my understanding is that it's basically a filter. I don't think Dolby used dynamic noise suppression like DBX. So you should be able to find a filter curve somewhere and then reverse that with an EQ plug-in.

Lotsa luck!

Dave

[magicd]

Ah! Just saw that the tape does use DBX, not Dolby (The record would have been a hit if were mixed in Dolby...)

So if I'm right that DBX is dynamic noise reduction, you need the inverse of that, which would be some sort of expansion.

Let us know.

Dave

[MIDI Life Crisis]

I don't think Dolby used dynamic noise suppression like DBX. So you should be able to find a filter curve somewhere and then reverse that with an EQ plug-in.

Lotsa luck!

Dave

Now there's something I never thought of for my old recordings with Dolby. Now if I only had a few thousand hours to bake my open reel tapes...

[Shooshie]

By the way, just for the record, Dolby encodes a track during recording, and decodes it during playback. Dolby C is the most pronounced. There may be instructions for "decoding" it with compressor and EQ, but it's not just a matter of a low pass filter or something.

Dolby C was not a big hit, because to get it right, the record and playback heads had to have their azimuth aligned precisely. The only tape deck that could claim to have perfectly aligned heads at all times was the Nakamichi Dragon, which could make recordings almost indistinguishable from the source when using Dolby C. High quality tape in a Dragon could stand favorably against 15 ips reel-to-reel.

But none of that matters here, because it's DBX. I'm just throwing that out there for the sake of info.

Shooshie

[HCMarkus]

Ah! Just saw that the tape does use DBX, not Dolby (The record would have been a hit if were mixed in Dolby...)

That's DOUBLY Dave. Ask Nigel.

[bayswater]

The DBX could be very difficult. I built one of these a very long time ago. IIRC correctly, it did three things. 1. Simple compression (mine was 2:1) . 2. Pre-emphasis on high frequencies (similar I think to Dolby B). So far those would be simple to reverse. You might not get it exactly the way it was, but if it sounds right, maybe that doesn't matter.

But:

3. A slight delay that varied by frequency. That was something to do with the effect of capacitors in the encoding circuit. I don't know how you would reverse that without the DBX decoder.

If you listen to the tapes you can tell if the differential delay was applied. It was noticeable on the recorded tapes.

[stubbsonic]

I did a set of transfers with 4 track cassettes and DPX (but not double-speed).

The first step would be to "stack" the cassette by playing it from beginning to end, just to make the cassette's take-up reel stack at playback speed. (this will remove one potential difference in playback speed).

Then record the forward side of the tape (with varispeed off) from the absolute beginning. Start record on the DAW first, then start the tape. On the second pair of tracks, record the backwards tracks in the same way.

You will now be able to zoom way in and find the onset of noise (where the clear tape leader ends and audio tape begins) as your start sync point. Align that initial noise as accurately as possible.

Then go to the far end of the track and look at where the noise stops (where the end leader begins). See how far off those are from each other. Depending on the nature of the material and how may songs are on the cassette, you can distribute fractions of this offset between songs. Unless a stereo track is somehow split between the forward & backward tracks, it might not matter.

I'd suggest getting all that alignment stuff done before doing the speed edit. I usually use Audacity for the varispeed stuff. Though DP may have a way to do this.

For the DBX, as Magic Dave suggests, it requires expansion. I used DP's expander and it worked ok. You have to find the sweet spot for the threshold & ratio. After that, EQ will help tone down any hyped frequencies. I don't recall delay being an issue when I did this before, but the source was pretty ratty and I wasn't listening for it.

Good luck! Let us know how it goes.

[wvandyck]

Maybe the easiest solution would be to pickup a Yamaha MT3X or similar on eBay.

My cassette 4 track is hardly ever used these days but it's ready to go when needed.
I gave mine away after transferring all tape content to aiff. Fast forward a couple of years- ended up picking up a unit from ebay. No plans to get rid of it any time soon.

Good luck.

[mikehalloran]

Maybe the easiest solution would be to pickup a Yamaha MT3X or similar on eBay.

My cassette 4 track is hardly ever used these days but it's ready to go when needed.
I gave mine away after transferring all tape content to aiff. Fast forward a couple of years- ended up picking up a unit from ebay. No plans to get rid of it any time soon.

Good luck.

That's your only real solution.

Cassettes use dBx II. You might find a stand-alone decoder (they did exist) but used Yamaha, Tascam and Fostex units are pretty easy to find. IIRC, each used a different track spacing in the head for the four tracks. Fostex 4-tracks match a standard 2-track cassette head and Tascam doesn't. I'm remembering that Yamaha doesn't either but I could be wrong. It's not that you can't play back a Tascam tape on a Fostex or Yamaha but output and noise will be inconsistent track to track.

dBx I used a compander/expander (their term) algorithm triggered by tha bass. dBx II for cassettes used a different algorithm that ignored the bass. In any case, you need to get the tapes to speed for it to work properly--playing back at 1 7/8" and decoding will not sound good at all.

Dolby B, C and S, likewise need the decoders and are most easily found in decks that have them. There is no statc EQ curve that you can apply and Dolby has refused to allow plugin decoders to be written or marketed.

I recently found a Dolby B encoder/decoder with adjustable calibration for $25 on eBay. This lets me fiddle with a knob on some of the cassettes that people send me till I find the sweet spot for decoding.

I still maintain my old Technics and Akai decks with Dolby B, C and dBx. You never know...

[Babz]

For sure a real Yamaha tape machine would be the best solution, and I did peruse Ebay a bit, but believe it or not these things are still going for a couple hundred bucks for one in decent shape.

I'm cash challenged, and can't manage that kind of expense for one nostalgic personal tune. That's why I was hoping I might find some kindly soul out there who might have an old machine lying around, who might be willing to transfer a couple of tracks for me.

And if I'm looking at hundreds of dollars for an oddball restoration project like this, I have to wonder if that money might be better spent on something like the Izotope RX 4 package (which is also something I would probably only use once in my life, but potentially maybe more…)

Best,
Babz

[Babz]

Perhaps I should explain the larger nature of the project.

I had this 80s urban contemporary group called Kiss & Tell (really a duo, my songwriter/singer partner + myself). He was immensely talented, but our best tunes never got recorded, and he is long gone.

What survives are a few tunes that I did in my home studio with the 4-track. (They are actually 3 audio tracks + a SMPTE code track that I used to sync to Performer playing back MIDI hardware instruments.) The tunes are fairly decent quality for 4-track, but borderline by today's standards.

I got rid of the 4-track years ago, but I have stereo DAT mixdowns of the tunes. (I also kept the original 4-track cassettes with the raw multi tracks.)

I transferred a stereo DAT track over to DP and was then tasked with making it sound the best possible for posterity using what tools I have available today. I threw a limiter on there, and that was basically going to be it.

BUT THEN ... Well, you know that kick is a little too boomy. And there are a few drum fills here and there that are too loud. So I started playing around with the DP's new Dynamic EQ, and was pretty impressed by how much I could manipulate parts of a stereo recording. OK, that helped.

BUT THEN ... Well, you know things are a little thin. Only had limited tracks back then. What if I added a background string pad here and there? And maybe some BG Vox on the bridge. And ... Next thing you know, you're trying to glue quiet background parts onto an existing stereo master mix. Now the lead vocal is getting a little lost.

SO THEN, I thought ... What if I could get the isolated lead vocal track off the original 4-track and layer that in. And maybe even use some alternate takes to do some double-tracking effects to thicken up the lead vocal on the chorus. And ...

So, that's where I'm at. I'm probably half crazy to have gotten as far as I have.

I actually only need one (maybe two) tracks off the cassette. And they will be used to layer over the original stereo master, and only in certain sections. Hopefully. Maybe. IF ONLY.

Or I could just come to my senses and stop trying to polish this dusty old jewel.

Maybe I'm just chasing unicorns.

Babz

[EMRR]

I've transfered and remixed a few albums originally done to a cassette 4 track that were mixed directly into a CD recorder, done this on several different occasions. Even having the original 4 track (in great shape), there's no such thing as a speed match from one pass to the next. When you line up any song against the original mix, there will be no match, so I'd never expect any success with multiple transfers of the same song. Buy or borrow any working 4 track for this job. You might find a transfer house that will do it for reasonable fee too.

[Babz]

Thanks, EMRR. Your experience is definitely helpful.

This particular track is relatively short and quantized at a single bpm. I was able to take the stereo DAT track into DP and line it up with a click and bar lines. Any tiny amount of drift can be fixed by analyzing beats and using the Adjust Soundbites To Sequence Tempo command.

Doing a true remix using the original track multitrack cassette isn't really possible. The cassette only contains the vocals and guitar. Most of the tracks for the tune were supplied by MIDI hardware instruments that were triggered live and synced to the audio via SMPTE. I don't have most of those hardware instruments anymore. I could substitute modern software instruments, but that would lose the vintage 80s vibe of the track. That would also be going too far. The track is 90% fine as is. I am just trying to balance a few things in the mix and add a few new background parts. This is really more of a remastering project than a remix. Or at least it was supposed to be.

Best,
Babz

[mikehalloran]

I'm with Doug on this.

I'm also in the same boat as you. There were some projects that I did on a borrowed Fostex X-15 back in the day for a magazine column that I wrote (just to see if I could do them on the cheap). It turned out well and I'm able to do a lot with the cassette master (thanks to RX 3) but... I'd really like to have at the original tracks.

My buddy's X-15 is still available but it mixes to 2-track only–no direct output. Since this is a 1 7/8" machine with standard head spacing, I tried to do 2 passes from my Technics and Akai. The direct drive Technics was better but perfect sync was not happening.

OK... I did some research and found a few Fostex models that could play back my tapes with direct out on all 4 channels and have Dolby B be able to switch out (the X-15 doesn't have Dolby). A Fostex X-28 showed up with the features I need and I snagged it for $50. I'm using rubber conditioner to try to get the pinch roller back in shape and then I'll see what happens. The electronics are a little noisier than I like but I'll teach RX 4 to filter that out.

If you are going to revive old tape, especially cassettes, RX will be your new best friend. Should you find someone to do the transfer, just have them do a direct to digital applying dBx. Use RX to clean up the noise and get rid of hum. It's amazing.