Evolution of cassette decks (1970s Akai & Marantz vs 1980s Technics etc)

[Werner]

It is whatever AudioTester uses by default, probably something log-like for efficiency. Since source and display are in sync (with a three-header) this does not matter. Compensation for the head-to-head latency, 150 points per graph, perhaps 2 minutes or so. Characterising a tape (responses, MOL, SOL, noise, relative bias and sensitivity) takes me 20-30 minutes.

Cassette decks are specified at -20dB relative to either Dolby level or DIN/IEC-zero (these are just 1.2dB apart, not much difference), i.e. the lower graph on my picture. The other levels are added because they can be interesting. Some magazines in the past tested at -20 and 0dB. When I started this I adopted Alex Nikitin's (ex-Creek, now A.N.T.Audio) display format. This way at least two people are showing graphs that can be compared with some validity.

 

[notevenclose]

I'd gladly pay to have the 570D refurb'd by a cassette deck expert if I knew it would improve its performance, but what if what I'm hearing is simply the limitations of 1970s cassette deck technology?

The 570 in its pomp was a very fine-sounding deck. That said, yes, 70s cassette deck technology does have its limitations, but properly set-up it should be capable of very decent results. It's potentially in a different class to your Marantz or Technics alternatives.

Back in the day, I dimly recall the 760 was the better-selling version (essentially the same unit, just a more conventional rack-friendly case) but I'd imagine the 570 would be the more fondly-remembered and probably more collectible.

 

[ToTo Man]

Didn't see the clips but just wanted to say that this is frequently due to a combination of tape skew and azimuth misalignment. The latter usually manifests itself on taper recorded on a different machine with a slightly different azimuth than your 570. If you can recalibrate it afterwards, try adjusting the azimuth some to see if it gets worse/better.

I noticed this on my two RS-B11W decks, when I play a tape recorded on one deck back on the other, the HFs are rolled off in the left channel (-4dB weaker above 16kHz. Tapes played back on the same RS-B11W they were recorded on do not display this imbalance so the heads on the two decks must be aligned differently. I guess this is why it's a good idea to hold onto the deck you made all your old recordings on!

 

[ToTo Man]

The 570 in its pomp was a very fine-sounding deck. That said, yes, 70s cassette deck technology does have its limitations, but properly set-up it should be capable of very decent results. It's potentially in a different class to your Marantz or Technics alternatives.

Back in the day, I dimly recall the 760 was the better-selling version (essentially the same unit, just a more conventional rack-friendly case) but I'd imagine the 570 would be the more fondly-remembered and probably more collectible.

I also had a 760D (two in fact!), but ended up selling them as they exhibited similar problems to my 570D and I didn't know anyone who could sort them for me. Wish I'd kept one of them as it was a lovely looking deck...

 

[Zombie]

I guess this is why it's a good idea to hold onto the deck you made all your old recordings on!

Or get one with adjustable azimuth

 

[notevenclose]

I also had a 760D (two in fact!), but ended up selling them as they exhibited similar problems to my 570D and I didn't know anyone who could sort them for me. Wish I'd kept one of them as it was a lovely looking deck...

Akai is another of the great 'lost company' brands from the 70s heyday of Japanese audio (along with Sansui and Aiwa).

Amps weren't brilliant, but the tape decks, both cassette and open reel, were of a consistently very high standard for a long time, and also far more reliable than cassette decks from the majority of their mass-market competitors. The receivers used to sell very well too, although I always thought was primarily down to the tuner performance.

I know the name still exists on some sort of shite for playing electronic ping-pong or something of that nature, but as is so often the case I very much doubt that's got anything to do with the original brand.

 

[ToTo Man]

Akai is another of the great 'lost company' brands from the 70s heyday of Japanese audio (along with Sansui and Aiwa).

Amps weren't brilliant, but the tape decks, both cassette and open reel, were of a consistently very high standard for a long time, and also far more reliable than cassette decks from the majority of their mass-market competitors. The receivers used to sell very well too, although I always thought was primarily down to the tuner performance.

I know the name still exists on some sort of shite for playing electronic ping-pong or something of that nature, but as is so often the case I very much doubt that's got anything to do with the original brand.

My uncle had Akai amp and tuner separates from the 1970s that I always lusted after. He did donate his Akai AA-1135 to me when I was 13 or 14 as it kept blowing fuses on start up. I can't remember what the problem was but it was an easy fix for my local tech. The bill for the repair was around £50 and I remember the tech asking me if I was sure I wanted to spend so much on something that wasn't worth a lot of money! This was before I discovered eBay (around 1999 I think) so I had no idea what vintage hifi was worth at that time. However, it turned out to be money well spent as the Akai's performance was a colossal step up from the BPC I'd been using from RicherSounds until then (I had a Sherwood amp and a Denon DRA-375D receiver). The AA-1135 remained my main amp until I moved on to the likes of the Yamaha CR-1000, CR-2020, Pioneer SX-1250, when I succumbed to statement pieces from the 'receiver wars'. I also owned an AA-1150, AA-1175 and AA-1200 (the latter two units had dual-mono transformers), this was when you could still pick these units up fairly cheaply, but ended up moving them on as I ran out of shelf space to display everything! The AA-1135 was the last to go, mainly due to sentiment, - it was the unit that sparked my obsession with vintage hifi.

 

[ToTo Man]

Or get one with adjustable azimuth

Good point. Though without the experience or test equipment I wouldn't feel confident in my ability to get the azimuth back to factory spec after messing with it, so a safer option would probably be to have two decks, one with correctly set azimuth and one to mess about with!

 

[Arkless Electronics]

My Tandberg TCD-440A's have a panel which pops open when you press it and reveals user adjustable azimuth control. IIRC there is a test oscillator you switch on and then set it up on it's own meters.

 

[Werner]

Yes, but that is to align the record head’s azimuth to the playback head’s. Doesn’t help at all with the replay of alien cassettes.

 

[ToTo Man]

Has anyone else noticed that when ''Cassette Comeback" gets a new deck, his video basically consists of him unboxing it, connecting it up, putting a tape in, checking transport functions work, playing and recording on it, a quick tweak of the bias, and the results are almost always great. He never seems to have any issues with dirty or worn out heads, damaged pinch rollers, azimuth misalignment, etc. I guess that kind of stuff doesn't make for good viewing!...

 

[337alant]

My Tandberg TCD-440A's have a panel which pops open when you press it and reveals user adjustable azimuth control. IIRC there is a test oscillator you switch on and then set it up on it's own meters.

Restoring my TDC-440A is very high on my list of things to do love this cassette deck.
Alan

 

[Arkless Electronics]

Restoring my TDC-440A is very high on my list of things to do love this cassette deck.
Alan

Got two... and a TCD-320. Doubt I'll ever use them. Certainly good decks though yes. NEAL don't get much attention but are very good also. I have a 103 that needs a pinch roller and that was superb when working properly.. the best two head machine I've heard in fact.

 

[notevenclose]

Restoring my TDC-440A is very high on my list of things to do love this cassette deck.
Alan

Tandberg cassette decks sounded great, but IME the problem was reliability, where they simply couldn't match the Japanese. They were excellent with spares and back-up (they needed to be), but there always seemed to be a 320 in bits in a corner of the workshop of both Tandberg dealers I worked for. The open reels were fabulous as well, happily reliability was never an issue with those.

 

[ToTo Man]

I have a question about cassette deck bias and EQ:

My Technics RS-B11W has no external user-selectable bias or EQ presets, it automatically sets bias and EQ by sensing the tab positions on the cassette that's been inserted. Many vintage cassette decks have separate preset buttons for bias and EQ. My GXC-570D however has only a "Tape Selector" switch, which I presume combines bias and EQ into the one preset. I assume this means that this switch must be in the correct and same position for BOTH recording and PLAYBACK for the FR and distortion not to get messed up?

Also, the 570D's Tape Selector has three settings: 'Low Noise', 'Chrome' and 'FeCr'. I've never seen a FeCr tape so assume they went defunct before I was born. When internally calibrating a deck like the 570D, it is possible to configure these presets to a tape type other than specified? E.g. could the 'Chrome' setting be calibrated for Maxell XLII and the 'FeCr' setting for TDK SA90, or is it not possible to adjust the FeCr trim pots to cobalt tape formulation? (I realise I won't be able to use metal formulations in this deck, but I have an equal cache of NOS Maxell XLII and TDK SA90 so it would be good if I could get equally good results with both).

 

[Werner]

I assume this means that this switch must be in the correct and same position for BOTH recording and PLAYBACK for the FR and distortion not to get messed up?

Yes.

E.g. could the 'Chrome' setting be calibrated for Maxell XLII and the 'FeCr' setting for TDK SA90, or is it not possible to adjust the FeCr trim pots to cobalt tape formulation?

As far as I can see the 570 has full alignment for type I, partial for II, and none at all for III. III is probably a combination of type I bias, standard type II/IV 70us replay eq, and dedicated hardwired FeCr recording eq.

You should expect a very big effort for redesigning the deck's replay eq (to make it compliant with IEC 1981), and for reworking record eq (to make it match the new replay eq as well as modern tapes, which are quite unlike the tapes of 1974!).
Maybe the FeCr switches can be wired to the oscillator board, to select a second Cr position. In that case you can have a setup for SA and for XLII (which typically demands a higher bias than SA). But it will be hard to implement. If not you better set up for 1986 or 1988 SA (which is very close to the 1987 IEC type II reference), or for 1991 Maxell SXII (which sits between SA and XLII).

But it is too early for such decisions. First things first:
1) get the transport section 100% working
2) assess the state of the heads
3) take response graphs in replay and record, see how far they are removed from post-1981 normal.

 

[ToTo Man]

Yes.



As far as I can see the 570 has full alignment for type I, partial for II, and none at all for III. III is probably a combination of type I bias, standard type II/IV 70us replay eq, and dedicated hardwired FeCr recording eq.

You should expect a very big effort for redesigning the deck's replay eq (to make it compliant with IEC 1981), and for reworking record eq (to make it match the new replay eq as well as modern tapes, which are quite unlike the tapes of 1974!).
Maybe the FeCr switches can be wired to the oscillator board, to select a second Cr position. In that case you can have a setup for SA and for XLII (which typically demands a higher bias than SA). But it will be hard to implement. If not you better set up for 1986 or 1988 SA (which is very close to the 1987 IEC type II reference), or for 1991 Maxell SXII (which sits between SA and XLII).

But it is too early for such decisions. First things first:
1) get the transport section 100% working
2) assess the state of the heads
3) take response graphs in replay and record, see how far they are removed from post-1981 normal.

Thanks Werner, you're helping me to improve my knowledge of how cassette decks work! I understand the most important thing is to get the heads and transport working properly. I'll be sending my 570D to df_genius soon for restoration. Calibration will be performed after the head/transport restoration is successful (fingers crossed!).

I recently bought 25 units of Maxell XV (rebranded Maxell UR), so I suppose it makes sense to start with optimising the 'Low Noise' preset on the 570D for this tape formulation. I assume this will be an easier job than reworking the Chrome and FeCr circuits?

Regarding the RS-B11W, how close would you expect a deck from 1983-1984 to be from the most recent (post-2000?) formulations of TDK SA and Maxell XLII and XLII-S? I have no technical measurements to analyse, but to my ears recordings made with the B11W on modern SA and XLII sound good and surprisingly similar (I can of course hear small differences between them but neither tape sounds obviously 'wrong', if that makes sense). Am I correct in thinking a deck that's factory biased for SA should sound brighter with XLII, and a deck that's factory biased for XLII should sound duller with SA?

PS - When you say the record and playback EQ of pre-1981 tapes is very different, is this the kind of thing you mean? This is periodic pink noise recorded and played back on my Marantz 5220 using Maxell XV Type 1. As you can see, the Marantz's response is rather different to the response from my RS-B11W!

 

[notevenclose]

I have a question about cassette deck bias and EQ:

I assume this means that this switch must be in the correct and same position for BOTH recording and PLAYBACK for the FR and distortion not to get messed up?

IIRC, FeCr tapes play back on Chrome setting just fine. Bias is only relevant at the recording stage.

I used to get very good recordings on a couple of Aiwas (a 6550 first, then a 6700) using Sony FeCr tapes (Aiwa was effectively a division of Sony, so no big surprise).

One of the biggest hifi mistakes I ever made was not buying a 6900, which I think was Aiwa's finest hour — I plumped for a Nakamichi 680ZX instead, but it was a pain in the arse, far too clever for its own good, spent half its life being serviced. I was eventually offered a swap for a 582, decent enough, but a bit plasticky.

If I were given my choice of absolutely any 'classic' cassette deck, the AD6700 or 6900 would be the first two on the list.

 

[Werner]

Am I correct in thinking a deck that's factory biased for SA should sound brighter with XLII, and a deck that's factory biased for XLII should sound duller with SA?

Yes.

PS - When you say the record and playback EQ of pre-1981 tapes is very different, is this the kind of thing you mean?

Deck design should be like this:

1) first the playback circuit is designed to give, when combined with a certain head, a specific desired response from a specific prerecorded alignment tape
2) then the recording bias is chosen, aiming at a certain MOL/SOL balance for a specific blank and head
3) then record eq is designed to give a flat response when recording that specific tape with the in 2) selected bias.

The problem is that part 1) was pure chaos before 1981. There were alignment tapes, but no-one could agree on what their ideal response should look like, at least not when not using the very same (crappy) head as used when setting the standard. Adding insult to injury Philips allowed very generous tolerances on setting the playback response (I've heard 5dB, perhaps even +/-5dB). As a result manufacturers played dirty, offering a rolled-off replay response (and a tilted-up recording response, to even this out), allowing them to claim artificially-enhanced signal-to-noise ratios (thanks to the treble roll-off), and of course customer lock-in to their own brew of equalisation curves.

After 1981 new alignment tapes were made available, and there was more agreement on what they meant. Even so ...

Another issue is that the tapes of the 70s were rather crude compared to what came after, say, 1985. A deck producing a flat response on an old tape does not necessarily remain flat on a new tape, when using the same setup procedure.

 

[Arkless Electronics]

Tandberg cassette decks sounded great, but IME the problem was reliability, where they simply couldn't match the Japanese. They were excellent with spares and back-up (they needed to be), but there always seemed to be a 320 in bits in a corner of the workshop of both Tandberg dealers I worked for. The open reels were fabulous as well, happily reliability was never an issue with those.

One of my TCD-440A's arrived with me non working and I never got round to fixing it but the other one and the TCD-320 were used on and off for 5 years or more with no issues. Cassette was never a big source for me so they prob only got an hour a week use though...