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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 6th May 2023, 10:28 am   #1
PJay1966
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Default Playback sound quality Tandberg 3341X

Hi Everyone

I have made really good progress restoring an old Tandberg 3341X R2R. New belts fitted, cork clutches replaced and a general lubrication. Mechanically its working well. Yesterday I hooked it up to an amp and tried it out, by recording some music which I streamed from Amazon music into the tuner input on the amp. Playback of the recorded music sounded very bass heavy and seemed to lack much midrange and treble. It sounded a bit better when listening to the tracks with headphones connected to directly to the tape recorder but still not great.

I've spent hours on this machine, and would really like to get it working to a decent level so can anyone offer any advice on what to look at next?

Appreciate any help or advice, thanks!
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Old 6th May 2023, 10:48 am   #2
Welsh Anorak
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Default Re: Playback sound quality Tandberg 3341X

The obvious place to start is to clean the heads again and again. I'm sure you already have, but oxide can be very persistent. Then the azimuth perhaps? It's worth getting a pre-recorded tape you know is correct to see whether it's the record or playback path that's at fault.
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Old 6th May 2023, 11:34 am   #3
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Default Re: Playback sound quality Tandberg 3341X

Hi Glyn

Thanks for the advice I’ve cleaned the heads and tape path with isopropyl and it seems clean. I wonder if there’s anything else I could use that might be more effective that alcohol? I am also wondering if it could be tarnished contacts on the various edge connectors that are on the main board. I’ve cleaned a few of them which were black with tarnish so might try some brasso on a cotton bud for them.
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Old 6th May 2023, 11:41 am   #4
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Default Re: Playback sound quality Tandberg 3341X

It's unlikely that dirty edge connectors would cause a frequency response fault in isolation ie that was not accompanied by intermittency etc, although obviously they need to be bright and clean.

You don't want to be using anything 'stronger' than alcohol on tape recorder heads. Just be very thorough. I'd be thinking an azimuth issue myself.
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Old 6th May 2023, 12:03 pm   #5
Ted Kendall
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Default Re: Playback sound quality Tandberg 3341X

The tape could be over-biased. If head cleaning and azimuth checking doesn't answer, check the drive to the bias head is in bounds.
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Old 6th May 2023, 1:43 pm   #6
PJay1966
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Default Re: Playback sound quality Tandberg 3341X

Many thanks everyone. I have just spent the last hour cleaning in between watching the coronation. I must have got through dozens of cotton buds on the tape transport and heads and I removed and cleaned all of the edge connectors on the board. Sound is significantly better but still not as good as my Akai's. The last remaining issue is the supply reel running on slightly when the machine is stopped from play. Basically it causes the tape from the supply reel to have about an inch of slack as it enters the tape path. Not sure why this should be, I followed the mechanical adjustments in the service manual when I replaced the clutches, again any guidance would be appreciated!

Thanks everyone have a great long weekend..
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Old 6th May 2023, 3:19 pm   #7
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Default Re: Playback sound quality Tandberg 3341X

I'm guessing that the X suffix means that it uses Tandberg's patented cross-field head to apply bias?

If this head wasn't in the right place when you made your recording, you will likely see the poor frequency response effect of too low bias.

Akai licensed this technique from Tandberg for their cross-field machines.

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Old 6th May 2023, 4:07 pm   #8
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Default Re: Playback sound quality Tandberg 3341X

Well spotted, David! The cross-field bias with extra head opens up a whole new avenue of checks!
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Old 7th May 2023, 12:55 am   #9
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Default Re: Playback sound quality Tandberg 3341X

Service manuals recommend testing playback response first. As said using a self made recording assumes the recorded frequency response is correct, but it may not be. This is regardless of whether the machines records with x field or not. The principle is to get playback response correct then adjust recording response to the machine's now calibrated playback response.

Very often I make a simple test using as reference the hiss on an unrecorded tape. With the tape playing, tape hiss should normally be considerably louder than preamp hiss, right up to the highest stated frequency for the tape speed. Momentarily stall the tape (eg:pull the pinch roller off the tape, or possibly carefully lift the tape off the playback tape head) and the loss of clean, sharp tape hiss should be audible. If not there's a playback issue.

If this machine is 3 head it's possible record and playback heads are misaligned. But there are multiple causes for loss of the highs in analog tape machines.

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Old 10th May 2023, 10:25 pm   #10
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Default Re: Playback sound quality Tandberg 3341X

Have you tried playing a known good tape? Any improvement over its own recordings?
Heads demagnetized?
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Old 11th May 2023, 11:26 am   #11
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Default Re: Playback sound quality Tandberg 3341X

Tim and Ben's advice is worth noting. If you don't have test tapes, then get a tape that you know sounds clean and sharp on the Akai and see how different it is on the TBerg. It's possible that alignment between the machines is different, so even if heads are perfect, it won't sound identical - but it'll be a start point, at least. Unless the TB's heads are way out of whack, a tape that's known to be crisp on the Akai should sound decent.

If you have access to a magnifier of some description, take a look at the head gaps on the TB. Do they form nice and sharp lines, or do you see some 'scatter'?

This company deals with reel machines, but the principles are the same and they know their onions: http://www.jrfmagnetics.com/tapeheadintro.html
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