Tandberg Model 12 'thin' no bass sound - UK Vintage Radio Repair and Restoration Discussion Forum

john116 · 25th Feb 2022, 10:12 am

Hi - using the internal speakers on my Tandberg Model 12, the sound seems a little 'thin', with very little bass. While am not expecting huge bass from the internal speakers, the sound is very treble biased. Any suggestions on what causes this?

Edward Huggins · 25th Feb 2022, 3:20 pm

The speakers on this are 7" x 4" units. Have you just recently "lost" the bass you had before - or is it the first time you have used it on its internal speakers?

john116 · 25th Feb 2022, 7:57 pm

I recently just bought it. If it was a valve machine I'd check coupling capacitors....

Ted Kendall · 25th Feb 2022, 11:59 pm

In the original Tape Recorder review of the 12, it was found that the flattest bass response on the built-in speakers was obtained with full bass lift.

ricard · 26th Feb 2022, 12:00 am

The primary suspect on this machine is the record-playback switch, where oxidization tends to cause all sorts of symptoms, including problems with playback equalization.

Another culprit could be the equalization switch, controlled by the speed selector. The switch itself is of a different design than the record-playback switch and usually doesn't cause problems, but the control mechanism could have become dislodged so that the switch contacts aren't mating as they're supposed to.

Part of the speed selector mechanism is a plastic cam which tends to crack with age, although I can't remember disruptive this is on the 12 - on the models 8, 9, 14 and 15 there's a metal stud which tends to fall out when this happens, causing the eq switch to remain in the same position at all times, but the 12 has a slightly different design.

john116 · 3rd Mar 2022, 11:45 am

Hi - Ricard, so the equalisation switch is a plastic slider type switch controlled by a bowden cable from the speed change selector. For some reason, it's not actually moving the switch to the correct position for 3 3/4" and 7 1/2". For the 1 7/8" it's ok as it pulls it back to the correct position. More investigation to do to see why it won't move over when the speed selector is moved (the cable just bends at the selector end of it).

John Caswell · 3rd Mar 2022, 5:05 pm

Solidified grease/oil perhaps, not allowing the mechanism to move.

John

25th Feb 2022, 10:12 am	#1
john116 Pentode Join Date: May 2008 Location: Sydney, Australia Posts: 156	Tandberg Model 12 'thin' no bass sound Hi - using the internal speakers on my Tandberg Model 12, the sound seems a little 'thin', with very little bass. While am not expecting huge bass from the internal speakers, the sound is very treble biased. Any suggestions on what causes this?

25th Feb 2022, 3:20 pm	#2
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,344	Re: Tandberg Model 12 'thin' no bass sound The speakers on this are 7" x 4" units. Have you just recently "lost" the bass you had before - or is it the first time you have used it on its internal speakers? __________________ Edward.

25th Feb 2022, 7:57 pm	#3
john116 Pentode Join Date: May 2008 Location: Sydney, Australia Posts: 156	Re: Tandberg Model 12 'thin' no bass sound I recently just bought it. If it was a valve machine I'd check coupling capacitors....

25th Feb 2022, 11:59 pm	#4
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,676	Re: Tandberg Model 12 'thin' no bass sound In the original Tape Recorder review of the 12, it was found that the flattest bass response on the built-in speakers was obtained with full bass lift.

26th Feb 2022, 12:00 am	#5
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Tandberg Model 12 'thin' no bass sound The primary suspect on this machine is the record-playback switch, where oxidization tends to cause all sorts of symptoms, including problems with playback equalization. Another culprit could be the equalization switch, controlled by the speed selector. The switch itself is of a different design than the record-playback switch and usually doesn't cause problems, but the control mechanism could have become dislodged so that the switch contacts aren't mating as they're supposed to. Part of the speed selector mechanism is a plastic cam which tends to crack with age, although I can't remember disruptive this is on the 12 - on the models 8, 9, 14 and 15 there's a metal stud which tends to fall out when this happens, causing the eq switch to remain in the same position at all times, but the 12 has a slightly different design.

3rd Mar 2022, 11:45 am	#6
john116 Pentode Join Date: May 2008 Location: Sydney, Australia Posts: 156	Re: Tandberg Model 12 'thin' no bass sound Hi - Ricard, so the equalisation switch is a plastic slider type switch controlled by a bowden cable from the speed change selector. For some reason, it's not actually moving the switch to the correct position for 3 3/4" and 7 1/2". For the 1 7/8" it's ok as it pulls it back to the correct position. More investigation to do to see why it won't move over when the speed selector is moved (the cable just bends at the selector end of it).

3rd Mar 2022, 5:05 pm	#7
John Caswell Hexode Join Date: Jul 2009 Location: Wokingham, Berkshire, UK. Posts: 437	Re: Tandberg Model 12 'thin' no bass sound Solidified grease/oil perhaps, not allowing the mechanism to move. John