Tascam 34B vs TEAC A3440

N

noisegeek

New member
I’ve been refurbishing old decks for a few years now. Recently picked up a 34B and a 32 to replace the A3440 and I gotta say there’s no level of tuning I can do to get the Tascams sound to stack up to the old A3440. The old TEAC just sounds sweet and smooth. Everything coming out sounds better than what went in. Even with a spectrum analyzer I can’t get the frequency and transient response as good as the TEAC. Even went as far as upgrading the OP amps and still no improvement. Is there something electronic wizardry going on in the A3440 that’s missing in newer ones? The heads are different than the A3440 but one wouldn’t expect a downgrade on a pro-sumer model 10 years newer. Anyone have experience with the circuitry on these?
 
I can’t say for sure…both machines use the 4558 and 4559 opamp…what I’ve learned from experience is the playback amp plays a key role in the sound of a machine, and what I do see on a somewhat macro level that’s different between the two is on the 34 the playback signal goes through a signal transformer first, presumably to mitigate DC in the signal path, which is not a bad idea, but the quality of the transformer and the circuit design is crucial to how well signal is handled dynamically. And then it goes straight into a 4558. On the A-3440 the first stage of the playback amp is a discrete transistor-based circuit block…no transformer. This may have something to do with the sound difference. In my experience there is nothing to rave about the signal transformers Teac used in their designs. So that’s one suspect area that might account for what you are experiencing. My first multitrack open-reel machine was a 3340S…the entire signal path, except for the headphone amp, is 100% discrete transistor-based…not a chip in sight. It’s one of the best sounding “prosumer” tape machines I’ve ever encountered…really sounded great. So maybe that discrete front-end on the playback side is a good thing on the A-3440.
 
Great information sir I appreciate it! And good catch! The swap from the 4558 to 5532 made no measurable difference. Then tried LM4562 still no difference so I think you might have something there with the transformers. It’s just weird how they nailed it back in the 70s but still felt the need to change it up. The 34 has a noticeable lower noise floor so maybe the engineers had to compromise a bit to achieve that?🤔. Looks like I have some diagrams to study. I’ll post back results If/when I find a fix✌🏻
 
Noise: don’t assume it’s a design issue. The A-3440 is many years older than the 34B…have either been recapped? My hunch is a power supply recap would help in either case, and the A-3440 may be in a worse state. Both units feature audio power supplies with discrete regulation adequate global and local filtration, etc. Sure it’s quite possible the discrete stage on the A-3440 is noisier than a 4558 or 4559, but, for sure, if the A-3440 is running all original caps, that machine is about 50 years old now…well due for a recap considering the type of caps used (vs. like the computer-grade stuff you might find in a bonafide “professional” machine like an Ampex MM or 3M M series machine). And they also used larger local filters in the A-3440 (100uF), which is more expensive and can have benefits, but the larger the capacitance the trade-off is HF performance, and in the case of a filter cap that means decreased performance passing HF noise to ground. The factory parts used likely have higher ESR than the equivalent period parts for the 34B, and certainly compared to anything modern. So that may also contribute to higher noise between the two, but I would start with recapping the power supply. Hm. It also looks like the secondary filter in the A-3440 could benefit from a parallel small value film cap for better HF bypass. They didn’t include that at least on the schematic.

Opamps: it’s such a wormhole. And you have to remember any solid state opamp whether discrete or integrated in a chip is an amplifier…it’s not a generator…it’s not a color box…it, in concert with the necessary surrounding components, either buffers signal, or provides gain to signal. That’s it. Yes different opamps have different noise, distortion, slew, bandwidth and open loop gain characteristics, among other things, but if the input signal is garbage, electronically speaking, they won’t fix that. They buffer or amplify the garbage. And they are highly dependent on their surrounding components. Sure it is possible to hear differences in noise level or sound character depending on the application and especially if you are replacing many opamps in a signal chain, but it is not a silver bullet. And I would never, ever, ever replace an opamp without measuring the changes…checking for changes in DC offset…checking for oscillation…checking how it handles a square wave input…that 5532 might be super unhappy in that application where you used it. But you won’t know it if you don’t check things like I mentioned above. Never ever consider one opamp as a “drop-in” for another just because it’s pin-compatible. Ever. Unless there is evidence-base that supports that is true (in other words somebody tried the same thing in the same device for the same amp stage and measured to verify the new part was happy). And THEN you use your ears and compare A to B to determine if the change is beneficial. It might not be. It’s been about 50/50 in my personal experience. So I think first you need to recap the supply and see if that helps your noise issues, and then from there replace the local filter caps, and then start replacing your coupling caps.
 
Interesting discussion, as I have wondered how the two models compared to each other.

I always liked the A-3440 better, though I dont have any hard evidence to tell anyone why a 34 would be inferior.
I own the 3440, never had a 34, but I would not think they would sound all that much different from each other.

As far as timeframe's go, they are not spread out very far. My older brother bought his A-3440 new in June '79,
(still has it), and I believe they were already available in late '78. Even when the 34 came out in '82, the A-3440 was
not discontinued, which I find interesting- if someone were looking to buy a new 4 track at that time, which of
the two to pick, assuming their $ price was close to each other. The A-3440 ran thru '83- the serial # date code verifies
that, as well as Teac brochures, one of my two 3440's is an '83 model, though despite atleast a solid 5 year run, I dont think
there were any service bulletins or design changes to the 3440. The matching 2A mixer/MB-20 had a few minor changes- the
knobs, switches- colors, etc..

If the A-3440 you had performed so well and sounded so appealing, why did you not just keep it?

ps: The 34 was reviewed in Modern Recording- loved that magazine (Tape Op nowadays not quite the same...) if you scroll
down here in the link, but the mag messed up the photo in the review! :)

 
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