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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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18th May 2018, 12:56 pm | #1 |
Triode
Join Date: May 2018
Location: Cornwall, UK.
Posts: 29
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Philips 4307 sound issue
I wonder if anybody might be able to help.
I have a Philips 4307 which I'm used to transfer a large number of tapes. I know it's only a very basic machine, but has been a proper workhorse and doing a good job. Most of the tapes I've been transferring are not exactly Hi-Fi to begin with so the Philips suits it's purpose (there is a better machine on it's way soon). Suddenly, between switching tapes, the audio quality has starting playing up. I clean the heads after every tape pass, so I know they are as clean as can be. The belts are recently replaced. I don't really know what I'm looking for in it's innards, but I've taken it apart and can't spot anything glaringly obvious. The sound is suddenly distorted, almost wobbly and warblely. The machine hasn't been moved, and I don't recall knocking, banging, damaging, etc. anything. I've worked through well over 1500 hours of recordings (therein might lie the problem!) with no problems at all. I know it's not the tape as I've been back to an old tape that was transferred fine, and that now sounds warblely and distorted. Here's a short snippet, so you can hopefully here what I mean - http://kernowbeat.co.uk/reeltoreel.mp3 Does anybody have any suggestions on what may be the cause of the problem?? Thanks in advance for any suggestions! Richard |
18th May 2018, 1:02 pm | #2 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,787
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Re: Philips 4307 sound issue
That's called flutter. It will be a mechanical problem, maybe a belt not riding properly on a pulley. Unfortunately I'm not familiar with these decks so can't give detailed advice.
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18th May 2018, 4:00 pm | #3 |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,196
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Re: Philips 4307 sound issue
That's a pretty severe case of flutter. Sounds like a pretty fast rotating shaft in the drive (maybe perhaps the main motor) has picked up something sticky and needs a good clean.
Martin
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18th May 2018, 5:31 pm | #4 |
Triode
Join Date: May 2018
Location: Cornwall, UK.
Posts: 29
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Re: Philips 4307 sound issue
Thanks, I'll definitely take apart again and give all the parts a good thorough clean.
The front felt pad is really worn, would this make any difference? Can replacements for these be found online? |
18th May 2018, 7:53 pm | #5 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,658
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Re: Philips 4307 sound issue
It isn't just the heads that need to be cleaned - the guides need doing as well. I'd be inclined to check the guides at either side of the head channel. Sometimes oxide can gather in the corners at the top and bottom of the tape path, giving rise to the sort of stick-slip in the file - the deposit can be so even as to look like an intended strip of paint.
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18th May 2018, 7:59 pm | #6 |
Dekatron
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
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Re: Philips 4307 sound issue
Also clean the capstan and pinch roller.
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18th May 2018, 8:05 pm | #7 |
Triode
Join Date: May 2018
Location: Cornwall, UK.
Posts: 29
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Re: Philips 4307 sound issue
Thanks. Capstan, pinch roller and guides all cleaned regularly. I've given the inside a thorough clean, include drive shafts and it has certainly improved quite a lot but still sounding like a bit of flutter remains. Considerably improved but still not quite right!
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19th May 2018, 10:12 am | #8 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
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Re: Philips 4307 sound issue
Listening to your recording, the treble response sounds quite good which suggests the rec/reply head, although maybe worn by now, is still working well. That flutter is really bad, is the motor still sitting firmly on its mountings?
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19th May 2018, 2:16 pm | #9 |
Triode
Join Date: May 2018
Location: Cornwall, UK.
Posts: 29
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Re: Philips 4307 sound issue
Thanks. I've check all mounts, tighten screws etc. Sound is now not really distorted but is now very muffled and quiet. I'm inclined to think the playback head is on its way out
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19th May 2018, 4:27 pm | #10 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,191
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Re: Philips 4307 sound issue
When you said 'tighten screws', did you touch any of the screws on the head assembly, or the tape guides? If so, you might have misaligned the head relative to the tape which will cause it to sound muffled. The correct way to re-align the head involves a special alignment tape, but you can do a reasonable job by reading the service manual to see what the screws do, and then adjusting them for the clearest reproduction of a known-good recorded tape.
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19th May 2018, 8:10 pm | #11 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Philips 4307 sound issue
I've had a look at the waveform in Audacity, but it didn't tell me much. I can hear a repeating speed variation; but at the resolution of my monitor, it's hard to see if or not the crests and troughs of the dominant note are getting closer together and further apart, or if that is just how the nearest pixels fall.
My gut instinct says spot of stubborn dirt on the capstan.
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21st May 2018, 6:07 am | #12 |
Triode
Join Date: May 2018
Location: Cornwall, UK.
Posts: 29
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Re: Philips 4307 sound issue
Thanks for all the suggestions. A good thorough clean and a manual realignment of the heads has much improved the sound. Nothing looked particularly grubby, but clearly there must have been some hidden dirt causing issues. It's certainly not perfect, I expect the heads are aligned quite as well as they could be.
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