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03-28-2023, 05:41 PM
rphase rphase is offline
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I have a jvc hr-s2901u and the picture looks good but the audio is vastly lower in volume and quality than my standard sony dvd/vhs player. I'm in the middle of backing up old home movies. I'm stuck between two hard choices, use the svhs player for good video but bad audio, or use the vhs player for lesser video but much clearer and louder audio. I've made sure the 2901u is indeed set to hi-fi and not linear. In fact changing the function settings from hi-fi to hi-fi l/r or setting it to norm or mix doesnt change the quality at all. I'm assuming changing it from hi-fi to norm is going from hi-fi to linear as there is no other perceivable way to change that, maybe you can't? Is there anything other than cleaning the head or using different cables I can do to trouble shoot this or am I just stuck with a defunct machine? Any insight is appreciated.
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  #2  
03-28-2023, 06:49 PM
timtape timtape is offline
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If there's no difference in the muffled sound quality between Hifi and Norm, either there is no Hifi track recorded to the tape (as with home movies shot on a VHS camera with no HiFi recording ability), or there is a Hifi track there but your VCR is unable to play it for some reason.

If you've confirmed via your Sony deck there is a Hifi track on the tape, manually adjusting player tracking on your JVC might bring back the Hifi track.

Some cheaper decks have Hifi but cannot be manually changed from Normal to Hifi. Are you able to switch between Normal and Hifi settings on your Sony, probably from the remote?

Often when there is a Hifi track, the VCR takes a few seconds at first to lock onto it, with the sound getting clearer as it switches from normal to Hifi sound tracks. On some decks when the deck has found a Hifi track the word Hifi comes on the screen for a few seconds.

But just because the audio is clearer on the Sony doesnt necessarily mean you are listening to a Hifi track. Maybe it is a normal (Linear) track and the Sony is just playing it back better. Differences in deck playback quality of the normal audio track are a common issue.


Can you provide audio samples, one from each player to confirm?

Last edited by timtape; 03-28-2023 at 07:35 PM.
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  #3  
03-28-2023, 08:46 PM
rphase rphase is offline
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Quote:
Originally Posted by timtape View Post
If there's no difference in the muffled sound quality between Hifi and Norm, either there is no Hifi track recorded to the tape (as with home movies shot on a VHS camera with no HiFi recording ability), or there is a Hifi track there but your VCR is unable to play it for some reason.

If you've confirmed via your Sony deck there is a Hifi track on the tape, manually adjusting player tracking on your JVC might bring back the Hifi track.

Some cheaper decks have Hifi but cannot be manually changed from Normal to Hifi. Are you able to switch between Normal and Hifi settings on your Sony, probably from the remote?

Often when there is a Hifi track, the VCR takes a few seconds at first to lock onto it, with the sound getting clearer as it switches from normal to Hifi sound tracks. On some decks when the deck has found a Hifi track the word Hifi comes on the screen for a few seconds.

But just because the audio is clearer on the Sony doesnt necessarily mean you are listening to a Hifi track. Maybe it is a normal (Linear) track and the Sony is just playing it back better. Differences in deck playback quality of the normal audio track are a common issue.


Can you provide audio samples, one from each player to confirm?
I believe you are right in that there is no hi-fi track at all and its linear audio. There is no ability to turn it off/on on the sony vcr but given that the jvc shows no difference no matter the setting I think is good evidence of that. Here are some samples.


Attached Files
File Type: mp3 jvc svideo.mp3 (489.2 KB, 3 downloads)
File Type: mp3 sony composite.mp3 (489.2 KB, 3 downloads)
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  #4  
03-28-2023, 10:40 PM
timtape timtape is offline
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Thanks for the two samples of the same section of audio, seemingly both normal (linear) audio.

Below are spectrograph screenshots of the audio samples you uploaded. They confirm listening tests that the JVC playback is both muffled AND contains noisy whistling tones in the upper frequencies (seen as horizontal lines in the screenshot).

The Sony playback is much clearer in the highs and has less whistling noise, suggesting the whistling tones are not on the camera recording but the JVC has added them. The Sony does add some tones of its own (see spectrograph) but mainly lower in frequency and are probably not so intrusive on the recorded speech.

This sort of problem is not new. As you say we shouldnt have to choose between good picture and good sound. Ideally the VCR chosen has both good picture AND sound.

Having said that...unfortunately extracting the best and clearest audio from the normal/linear track on each VHS tape is not always straightforward as the alignment of VCR audio head to tape is very sensitive to small angular errors, resulting in the muffled sound we hear such as on your JVC playback. I dont believe this is inherent to this JVC model or JVC VCR's generally. It's just a critical adjustment which can affect any VHS VCR playing back tapes recorded on different decks or cameras. Your Sony audio head probably just happened to be better aligned to your home movie tape.


Attached Images
File Type: jpg JVC audio (2).jpg (75.3 KB, 6 downloads)
File Type: jpg Sony audio (2).jpg (72.0 KB, 6 downloads)
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  #5  
03-28-2023, 10:44 PM
rphase rphase is offline
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interesting, thank you for the insight. im curious if its worth it to try and adjust the linear head on my jvc as i dont really want to use it as is (for my use case in which all my home videos are likely linear audio).
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  #6  
03-28-2023, 11:52 PM
timtape timtape is offline
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I've always made this adjustment every time I transfer a VHS or Beta tape. I cant demonstrate a recording of playback before adjustment, just after. Below is an example after adjustment.

It's ultimately your decision of course. Obviously there are some nasty high voltages inside the deck and care needs to be taken, especially if you have no experience with mains powered electronics. It involves taking the top cover from the machine and locating the correct screw on the audio head. There is only one correct screw and it must be adjusted slowly, carefully, probably less than a quarter of a turn with a suitable non magnetic screwdriver while listening carefully to the audio playback for clarity. Best to listen through an audio system which doesnt introduce a delay to the audio such as happens after running through a digital converter. That way you are getting instant feedback as to the effect of your careful adjustment.

It's also possible the face of the audio head itself is dirty or even worn enough to contribute to the muffled sound. Cleaning the head face correctly is advisable just in case.

Perhaps others here will have a photo of the audio head arrangement in your particular JVC deck where the correct (azimuth) screw can be identified and the other screws avoided.


Attached Files
File Type: wav VHS cam linear audio example.wav (1.95 MB, 5 downloads)
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  #7  
03-29-2023, 12:08 AM
rphase rphase is offline
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I have opened it to clean the head drum with paper/alcohol so I think ill give adjusting the audio head a go. I'll try to do some research on which screw I need to adjust. Thanks for the help.
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  #8  
03-29-2023, 07:01 AM
dpalomaki dpalomaki is offline
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Just a thought. If adjusting the heads makes one uncomfortable, one could make a recording with the sony and then substitute the audio from it with the video from the JVC in post production.
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  #9  
03-29-2023, 01:09 PM
timtape timtape is offline
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The diagram below may or may not apply to your JVC VCR's A/C head. Screw 2 adjusts azimuth. If yours (seen from the top) looks the same as this line drawing it's probably correct.

To enable easy return to the original factory setting, using a fine tipped felt pen I first make a small mark on the screw, lining up with another on the metal plate.


Attached Images
File Type: png JVC AC head screws.png (53.7 KB, 10 downloads)

Last edited by timtape; 03-29-2023 at 01:36 PM.
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  #10  
03-29-2023, 02:17 PM
timtape timtape is offline
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Just to add, sometimes when the azimuth screw is at the front side of the head, the tape as it is loading or unloading actually crosses over the top of this screw. In this case, to prevent the tape fouling on the screwdriver, be careful to remove the screwdriver before the tape loads or unloads against the head face.
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  #11  
03-29-2023, 08:02 PM
rphase rphase is offline
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So I tried messing with the linear audio head adjustment, didn't make any improvements but I did mark it and return it to the factory settings as you suggested. I picked up a vhs tape at a goodwill so I could hear what hi-fi sounded like on the unit. With that tape I did find that the audio settings on both the jvc and the sony could be changed and I could hear the difference, further confirming its all linear audio on my home movies. The audio setting on the jvc makes no difference while using a linear audio only tape and in fact will only visually change the setting its on if I go into the actual menu (when using a tape that only has linear audio) and not just use the remote. The remote works on a hi-fi tape and lets you adjust which audio its using. The sony was the same thing, doesn't let you change it on a linear only tape. On a hi-fi tape it makes a difference. Hi-fi sounded identical to my ears on both units. I would use the sony as the picture quality is only slightly less, some colors are washed out but it does not let you turn off superimpose, the text that pops up and says "play", as well as the tracking bar coming on. I don't fancy recording those. Ultimately I think I'll look around for another svhs player, within budget. I certainly can't afford a high end build in digital tbc unit. Thanks for all the help and insight @timtape

Last edited by rphase; 03-29-2023 at 09:02 PM.
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  #12  
03-29-2023, 09:05 PM
timtape timtape is offline
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Quote:
Originally Posted by rphase View Post
So I tried messing with the linear audio head adjustment, didn't make any improvements but I did mark it and return it to the factory settings as you suggested...
Well done on having a go, but if adjusting the azimuth screw didnt make the sound clearer, at some point it should at least have made the clarity worse, more muffled. So we slowly turn the screw the other way. The final small adjustment may be as small as a 1/16th turn of the screw. Were you listening directly to the sound as you adjusted? It's also important to listen to a section on the tape with lots of sharp, clear sound, like the hissing of wind through tree leaves or if a live concert, audience applause.

If there was no change made regardless of turning the azimuth screw, something else must be causing the muffled sound. We normally check the A/C head is clean. Only a tiny speck of dirt is enough to badly muffle the linear audio. Paper is not suitable on the AC head. A Q Tip soaked in IPA is good. 1 minute job. The audio head section is right at the top of the head face. The attached photo shows the exact section at the top of the head face where the audio is picked up.

If you have a large number of old tapes to transfer, fully cleaning the tape path, including the audio/control head, will probably need doing anyway, perhaps multiple times through the project.


Attached Images
File Type: jpg A C head w arrow.jpg (60.1 KB, 6 downloads)

Last edited by timtape; 03-29-2023 at 09:39 PM.
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  #13  
03-30-2023, 09:35 PM
rphase rphase is offline
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So I was able to find a spot on the tape where I could get a small improvement turning the azimuth screw. About a 1/8th turn clockwise. It made the audio less muffled, didn't help the volume levels at all but its neat to see some improvement. Tried cleaning the head too but no change after that. I have a jvc hr-s3900u on the way that appeared to be in good condition so I'm going to try that out. If its not an improvement than I'll just resell it.
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  #14  
03-31-2023, 03:29 AM
timtape timtape is offline
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Quote:
Originally Posted by rphase View Post
So I was able to find a spot on the tape where I could get a small improvement turning the azimuth screw. About a 1/8th turn clockwise. It made the audio less muffled, didn't help the volume levels at all but its neat to see some improvement. Tried cleaning the head too but no change after that. I have a jvc hr-s3900u on the way that appeared to be in good condition so I'm going to try that out. If its not an improvement than I'll just resell it.
Well done again. Tuning to the recorded azimuth wont usually increase the overall volume, it more restores the highs relative to the lows. Different brand VCR's might have somewhat different audio output levels. So long as it's a good capture and you can adjust the final level in post it shouldnt be a problem.

Unfortunately tuning wont diminish any sharp whistling tones added by the deck but getting the best audio clarity off tape more effectively masks such interference.
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