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Calling Reel-2-Reel Tape experts - TEAC A3440 15ips speed problems

I do really like these old Teac 4 track recorders, the earlier 3340 too. They were all over the place years back as no one wanted them, but no more. Very, very rare to see a really clean one as they were a small studio tool and a fair number ended up on stage with synth-pop or new-wave bands etc (OMD, Human League, Cocteau Twins etc). It is one if those things I really want to own but have absolutely no practical use for or place to keep!

PS From what I can tell from watching a few YouTube videos the internal build of the ‘70s Teacs looks second to none, just beautifully made and highly reliable. It surprises me they are often seen to be a tier below Revox. I can’t remember the model number but the equivalent two-track Teac is a lovely thing too. I get the impression, as with so much audio, that the later ‘80s versions were cost-cut and lacked the build quality of the ‘70s units and are harder to work on.
 
Tony L said:
I do really like these old Teac 4 track recorders, the earlier 3340 too. They were all over the place years back as no one wanted them, but no more. Very, very rare to see a really clean one as they were a small studio tool and a fair number ended up on stage with synth-pop or new-wave bands etc (OMD, Human League, Cocteau Twins etc). It is one if those things I really want to own but have absolutely no practical use for or place to keep!

PS From what I can tell from watching a few YouTube videos the internal build of the ‘70s Teacs looks second to none, just beautifully made and highly reliable. It surprises me they are often seen to be a tier below Revox. I can’t remember the model number but the equivalent two-track Teac is a lovely thing too. I get the impression, as with so much audio, that the later ‘80s versions were cost-cut and lacked the build quality of the ‘70s units and are harder to work on.
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I was looking for a youtube video of a 3440 teardown but instead found an American tech taking apart a 3340 (and with a bit too much of a gun-ho approach IMO!). From what I could see in the video, internally the 3340 looks more crammed than the 3440 so possibly harder to work for those with big hands. From a personal POV I prefer the external layout and styling of the 3440, it seems to straddle the olde worlde and modern eras, retaining the beautiful analogue VU meters but going to a totally solenoid transport operation. However, I'm probably biased in my opinion as the deck's been in the family for so long (my uncle bought it new). From a SQ perspective, as far as I can remember it produces excellent recordings but isn't quite on the same level as a 2-track B77, which is of course not surprising given it's a 4-track machine so uses half the track width that the B77 does. It'll be interesting to hear how good it is now that I've demagnetised the heads, AFAIK this was never previously done.
 
Reading the 3440 manual, the quick start guide says the output level knobs should be "set to around position 7", but doesn't explain why.
According to the specs at the back of the manual, the A3440's output voltage is 0.3Vrms, which seems very low compared to modern day sources. Presumably this 0.3Vrms output only applies when the output level knobs are set to max? I recall that the level of idle background hiss (with no tape playing) on this deck increased a fair bit when I went beyond position 7 on the volume control, but I can't say for sure if the noise increase was any less linear than that from going from 0 to 7. In other words, I can't recall if setting the 3440's output knobs to 7 and cranking the volume on my amp up more was any quieter than maxing them out and setting a lower volume on my amp. @337alant, what's you're preferred output level setting on your 3440?
 
@337alant, what's you're preferred output level setting on your 3440?

As far as I remember mine is still set to factory level of 308mv , I haven't used mine for years now so I'm not up to speed with this model
The manual says Max output of -2dB 600mv but with modern tape it may be capable of using 0dB 0.775mv and a 250nWb/m playback Cal tape ?

Alan
 
337alant said:
@337alant, what's you're preferred output level setting on your 3440?

As far as I remember mine is still set to factory level of 308mv , I haven't used mine for years now so I'm not up to speed with this model
The manual says Max output of -2dB 600mv but with modern tape it may be capable of using 0dB 0.775mv and a 250nWb/m playback Cal tape ?

Alan
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Thanks for the info Alan, very useful. I'm pretty sure mine is still factory spec and I don't intend to adjust any of the internal settings. I was just wondering what the best position is for the output level knobs on the front panel in terms of minimising background hiss from the deck's circuitry? I hear more background hiss when I go above 7 and I don't know if this is normal or not?
 
It's late at night but I was determined to squeeze in my first test record. T'was a success I think. Recording onto Maxell UD, tonally VERY similar to the source but with a nicely fattened up bottom end. Surprisingly good fidelity too!

50377162246_5b7fe61809_o.jpg
 
ToTo Man said:
I was just wondering what the best position is for the output level knobs on the front panel in terms of minimising background hiss from the deck's circuitry? I hear more background hiss when I go above 7 and I don't know if this is normal or not?
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Set them such that you use the same volume control range on the Yamaha as with your other sources. This will make no net difference to hiss, as the latter is entirely dominated by the TEAC's head amp (and of course by the tape). Remember that it is not about the noise in isolation, but about the ratio of signal to noise.
 
Werner said:
Set them such that you use the same volume control range on the Yamaha as with your other sources. This will make no net difference to hiss, as the latter is entirely dominated by the TEAC's head amp (and of course by the tape). Remember that it is not about the noise in isolation, but about the ratio of signal to noise.
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After some more experimenting last night it appears the TEAC's output is more powerful than I inferred from the specs that said 0.3Vrms. Setting it to max makes the deck play louder through my amp than my 2Vrms line sources so I backed it off until it roughly matched these and ended up with it set to around 8.

Some more thoughts on the test recording I made last night:
After the song I was recording finished I allowed the deck to continue recording 'silence' for a few seconds before I stopped the deck.
When I played the track back, I noticed the section of 'silence' I recorded had a much higher noise floor than the noise floor of the virgin tape. It actually surprised me how quiet virgin tape is!
It's been a long time since I've recorded to tape and, aside from cassette decks, my experience has been limited to this A3440 and a B77 that I last used in 2012, so I don't know how much the noise floor is supposed to increase after recording onto the tape. I assume it varies from deck to deck, and that better decks will record less residual noise?
I'm curious where the noise comes from? Is it mainly from the erase and record heads themselves or from the preamp circuitry attached to them? In other words, would upgrading/recapping the machine improve its SNR when recording or is it ultimately limited by the quality of the heads and the fact that is a 4-track targeted at the home musician and is not intended to be used in a studio setting?
Also, the tape I used to record onto was the reverse side of a test tape I previously recorded using this deck, and I could hear some bleed from tracks 2 and 4 coming through on tracks 1 and 3. Is it normal for this to happen?
I feel like I'm on a steep learning curve!

EDIT - I also noticed that when rewinding or fast forwarding the tape, I could hear faint 'chipmunk' sounds through the speakers even though I didn't have the cueing lever raised. Is it normal for the heads to pick up sound from tape running past it even when it's not in direct contact?
 
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High speed R2R machines can often kick out a very high output. Obviously it depends what’s on the tape and how hard you are pegging it into the red, but IIRC +10V is not unheard of!
 
I noticed the section of 'silence' I recorded had a much higher noise floor than the noise floor of the virgin tape. It actually surprised me how quiet virgin tape is!
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That is bias noise. It is very much like death or taxes: impossible to evade.

The theory is that during recording the record head acts as a play head for the virgin noise present on the tape. This noise, now an electrical signal in the head, interacts with the bias and gets printed back onto the tape, amplified. Once the bias signal is of a sufficient purity (i.e. low asymmetric distortion) the added bias noise is a constant. It may vary a bit with bias frequency, don't know.

With cassette bias noise is 2-3 dB above virgin noise, IIRC.

The fact that the TEAC shows off the difference between bias noise and virgin noise is a sign that its playback amplifier itself is of sufficiently low noise. That is not always the case. But since you said "much higher" I must wonder if there was still something coming in from the source or the record amp? You can do the test again with the deck's input pots turned to zero.

In the 90s some makes had cassettedecks that could defeat their erase head, the idea being that its contribution to bias noise would be deleted. Problem was, the erase head only contributes a negligible amount to bias noise. I tested this on a Nak CR-4 and came to 0.2dB or so, less than the error margin.
 
ToTo Man said:
After some more experimenting last night it appears the TEAC's output is more powerful than I inferred from the specs that said 0.3Vrms. Setting it to max makes the deck play louder through my amp than my 2Vrms line sources so I backed it off until it roughly matched these and ended up with it set to around 8.

Some more thoughts on the test recording I made last night:
After the song I was recording finished I allowed the deck to continue recording 'silence' for a few seconds before I stopped the deck.
When I played the track back, I noticed the section of 'silence' I recorded had a much higher noise floor than the noise floor of the virgin tape. It actually surprised me how quiet virgin tape is!
It's been a long time since I've recorded to tape and, aside from cassette decks, my experience has been limited to this A3440 and a B77 that I last used in 2012, so I don't know how much the noise floor is supposed to increase after recording onto the tape. I assume it varies from deck to deck, and that better decks will record less residual noise?
I'm curious where the noise comes from? Is it mainly from the erase and record heads themselves or from the preamp circuitry attached to them? In other words, would upgrading/recapping the machine improve its SNR when recording or is it ultimately limited by the quality of the heads and the fact that is a 4-track targeted at the home musician and is not intended to be used in a studio setting?
Also, the tape I used to record onto was the reverse side of a test tape I previously recorded using this deck, and I could hear some bleed from tracks 2 and 4 coming through on tracks 1 and 3. Is it normal for this to happen?
I feel like I'm on a steep learning curve!

EDIT - I also noticed that when rewinding or fast forwarding the tape, I could hear faint 'chipmunk' sounds through the speakers even though I didn't have the cueing level raised. Is it normal for the heads to pick up sound from tape running past it even when it's not in direct contact?
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You need to check all the internal voltages, oscillator output voltage and frequency etc etc to be sure all is well as these kind of things will have a big impact on recording quality and background noise.
A Sony TC377 I repaired about a year ago was all over the place and giving very quiet recordings with no top end and much louder on one channel than other and erase/bias oscillator voltages were out by as much as 30% or more.
Obviously others will be less afflicted... or not.. than this Sony.

A scope can be used but ideally something like these https://www.ebay.co.uk/c/10024692127

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=124346388949

Many others from the likes of Leader and Goodwill and HP will be available. I have a Marconi one like above and it is ideal for RF work as well as it goes to 1500MHz but the likes of the Topping are more modern and higher sensitivity but don't go as high frequency. In fact for the Topping I can't find any specs for max frequency...

Also ideal for all the AC signal levels that need checking.
 
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Arkless Electronics said:
You need to check all the internal voltages, oscillator output voltage and frequency etc etc to be sure all is well as these kind of things will have a big impact on recording quality and background noise.
A Sony TC377 I repaired about a year ago was all over the place and giving very quiet recordings with no top end and much louder on one channel than other and erase/bias oscillator voltages were out by as much as 30% or more.
Obviously others will be less afflicted... or not.. than this Sony.

A scope can be used but ideally something like these https://www.ebay.co.uk/c/10024692127

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=124346388949

Many others from the likes of Leader and Goodwill and HP will be available. I have a Marconi one like above and it is ideal for RF work as well as it goes to 1500MHz but the likes of the Topping are more modern and higher sensitivity but don't go as high frequency. In fact for the Topping I can't find any specs for max frequency...

Also ideal for all the AC signal levels that need checking.
Click to expand...

Would this be beyond the skill set of someone who's only ever ventured inside an amplifier to measure and adjust DC offset and idling current trim pots?
 
This site contains affiliate links for which pink fish media may be compensated.
ToTo Man said:
Would this be beyond the skill set of someone who's only ever ventured inside an amplifier to measure and adjust DC offset and idling current trim pots?
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Quite possibly yes....

In a service manual you will find things like ".... check at the junction of R246 and C334 for a clean and symmetrical sine wave of 100KHz +/- 2KHz of 40v peak to peak +/- 2V and adjust the core of L23 to obtain correct frequency and trimmer RV15 to obtain correct voltage...." This would be the main oscillator which generates the AC erase signal and the bias for the record head and first needs to be correct or any further adjustments downstream of this that change bias level for tape speed or tape type will all be out... hence you already need an oscilloscope and an AC Voltmeter capable of measuring accurately to well beyond 100KHz (a normal DMM or analogue multimeter is no good for this) and the knowledge to use them correctly and interpret the readings correctly. If you are really serious about R2R's you will soon need calibrated test tapes as well which can be expensive and are easily damaged.
Edit: You could get away with just the scope for the above but having both makes it rather easier.
 
Werner said:
That is bias noise. It is very much like death or taxes: impossible to evade.

The theory is that during recording the record head acts as a play head for the virgin noise present on the tape. This noise, now an electrical signal in the head, interacts with the bias and gets printed back onto the tape, amplified. Once the bias signal is of a sufficient purity (i.e. low asymmetric distortion) the added bias noise is a constant. It may vary a bit with bias frequency, don't know.

With cassette bias noise is 2-3 dB above virgin noise, IIRC.

The fact that the TEAC shows off the difference between bias noise and virgin noise is a sign that its playback amplifier itself is of sufficiently low noise. That is not always the case. But since you said "much higher" I must wonder if there was still something coming in from the source or the record amp? You can do the test again with the deck's input pots turned to zero.

In the 90s some makes had cassettedecks that could defeat their erase head, the idea being that its contribution to bias noise would be deleted. Problem was, the erase head only contributes a negligible amount to bias noise. I tested this on a Nak CR-4 and came to 0.2dB or so, less than the error margin.
Click to expand...
The difference between virgin tape noise and bias noise on the 3440 definitely sounds more than a 2dB or 3dB difference to my ears. I haven't recorded the deck's output onto my computer to analyse it, but when I get my B77 back I'll make the same recording on both decks and will also capture the DAC output directly and I'll upload all three recordings so you can compare them :).

Does bias noise increase when you re-record over tape that already has bias noise on it, or does the new bias noise replace the existing bias noise?

My uncle used this deck for multi-tracking. I'm not sure if he did it all on the 3440 (i.e. record on tracks 1, 2 and 3, then mix these down onto track 4, then record over tracks 1 and 2, then mixdown tracks 1, 2 and 4 onto track 3, etc) or if he mixed down 4 tracks from the 3440 onto the B77 and then recorded this back to the 3440. Whichever way he did it, the residual bias noise on the final mix-down must have been pretty loud?!
 
Richard
All noise should be erased during a fresh record ( the erase efficiency is stated as -65dB @1k )
So it should be silent, but new bias noise could be present if the Bias is not set correctly for the tape type in use.
Magnetised tape heads can also increase background noise.
Alan
 
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