Teac X-7 Sound Problem - UK Vintage Radio Repair and Restoration Discussion Forum

Timbo1963 · 8th May 2021, 10:54 am

I just got myself a Teac X-7 in really nice condition.
It was serviced in 2019 and was stored with little use afterwards.
Everything functions as it should, except I get noticeably heavier hiss on the Right channel than normal. If there is no line input signal connected it still hisses away albeit audio is there, functional and clear.
Any ideas?

TIMTAPE · 8th May 2021, 3:22 pm

There is always some hiss in a properly working machine. Sometimes the absence of hiss in the other track is the actual problem. Sometimes a weak, muffled recording draws attention to the normal level of tape hiss. An unusually high level of hiss in an otherwise good performing deck is a little unusual.

theredhouseinn · 8th May 2021, 4:26 pm

More info please.
If there is no line i/p where is your audio coming from? are you listening to a pre-recorded tape, or one made on your machine? Inspect the heads for hard deposits of oxide, is there uneven wear on the heads? etc., etc..
The cheaply engineered plastic cased X series was released by TEAC in the 80's to compete with the cheaper Fostex machines that hit the market then.
It may be that your machine needs to pay a visit to a test bench to determine what the problem is.
John.

DMcMahon · 8th May 2021, 7:04 pm

With a line input and set up for recording do you hear the hiss when the Monitor switch is switched to Source ? if so then the issue is most likely within the Playback amp electronics.

With the Monitor switch to Tape while recording do you hear the hiss in real time or only when the recording is played back ?

Do you hear the hiss when playing back a tape recorded on another machine ?

Could possibly be a noisy transistor (more likely) or IC in the PB/Record amps but difficult to prove without diagnostic tests.

David

8th May 2021, 10:54 am	#1
Timbo1963 Diode Join Date: May 2021 Location: London, UK. Posts: 1	Teac X-7 Sound Problem I just got myself a Teac X-7 in really nice condition. It was serviced in 2019 and was stored with little use afterwards. Everything functions as it should, except I get noticeably heavier hiss on the Right channel than normal. If there is no line input signal connected it still hisses away albeit audio is there, functional and clear. Any ideas?

8th May 2021, 3:22 pm	#2
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,969	Re: Teac X-7 Sound Problem There is always some hiss in a properly working machine. Sometimes the absence of hiss in the other track is the actual problem. Sometimes a weak, muffled recording draws attention to the normal level of tape hiss. An unusually high level of hiss in an otherwise good performing deck is a little unusual.

8th May 2021, 4:26 pm	#3
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: Teac X-7 Sound Problem More info please. If there is no line i/p where is your audio coming from? are you listening to a pre-recorded tape, or one made on your machine? Inspect the heads for hard deposits of oxide, is there uneven wear on the heads? etc., etc.. The cheaply engineered plastic cased X series was released by TEAC in the 80's to compete with the cheaper Fostex machines that hit the market then. It may be that your machine needs to pay a visit to a test bench to determine what the problem is. John.

8th May 2021, 7:04 pm	#4
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,600	Re: Teac X-7 Sound Problem With a line input and set up for recording do you hear the hiss when the Monitor switch is switched to Source ? if so then the issue is most likely within the Playback amp electronics. With the Monitor switch to Tape while recording do you hear the hiss in real time or only when the recording is played back ? Do you hear the hiss when playing back a tape recorded on another machine ? Could possibly be a noisy transistor (more likely) or IC in the PB/Record amps but difficult to prove without diagnostic tests. David