Technics M5 Tape Deck - High Frequency Issue - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 21 Old 03-20-2017, 08:25 PM - Thread Starter
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Technics M5 Tape Deck - High Frequency Issue

I'm having an issue with my Technics M5 tape deck which involves the loss of high frequencies in the left channel. Under regular listening conditions, the loss is not noticeable to my ears, but when I analyze recordings that I've transferred to my computer, I see that frequencies above 16 kHz are not as strong as they should be. (Not clipped, just weak/soft). The right channel appears to be fine.

I recently caught the issue while transferring some records over to my computer. (I use the record level knobs on the deck to control the output volume to my computer to prevent clipping/distortion). The frequency response starts to diminish past 16 kHz, though sometimes it will try to capture some high frequencies depending on how loud the volume is. Pops and clicks on the record are some examples. Reviewing some recordings that I made a few years ago do not show any degradation in the left channel, so this is something that recently started. Bypassing the tape deck and recording straight from the amp via the tape out correctly captures frequencies over 16 kHz, so that rules out the amp and record player.

While playing back a tape, I noticed that the high frequencies in the left channel are also hampered, particularly those present in the tape hiss. My guess, based on the age of the tape deck (1981-ish), is that the line output filter capacitor for the left channel is going bad and is taking a toll on the high frequencies. Does this sound logical? I can replace the capacitor if this is the case.

Attached are some spectral views. 1st one is of a record, 2nd one is of a tape played back in the deck.
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post #2 of 21 Old 03-20-2017, 08:39 PM
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Originally Posted by snowdog 88 View Post
I'm having an issue with my Technics M5 tape deck..
First clean and de-mag the heads. Use a fresh tape to test. After that...it gets expensive....

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post #3 of 21 Old 03-20-2017, 09:33 PM
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Quote:
Originally Posted by snowdog 88 View Post
while transferring some records over to my computer.(I use the record level knobs on the deck to control the output volume to my computer to prevent clipping/distortion).
So how are you cabling the phono to the computer?

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post #4 of 21 Old 03-21-2017, 07:29 AM - Thread Starter
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Originally Posted by citizen arcane View Post
So how are you cabling the phono to the computer?
RCA phono cables.

Record player > amp > tape player > sound card.

Remove the tape player from the setup and the high frequencies in the left channel are there.

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Originally Posted by Russ69 View Post
First clean and de-mag the heads. Use a fresh tape to test. After that...it gets expensive....
I don't think the tape head is at fault since passing the audio through the deck (not recording to tape) also results in the high frequency loss.

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Last edited by snowdog 88; 03-21-2017 at 07:35 AM.
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post #5 of 21 Old Today, 08:40 AM
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Quote:
Originally Posted by snowdog 88 View Post
RCA phono cables.

Record player > amp > tape player > sound card.

Remove the tape player from the setup and the high frequencies in the left channel are there.


I don't think the tape head is at fault since passing the audio through the deck (not recording to tape) also results in the high frequency loss.

99% of audible musical content is at frequencies below 8kHz.

Brushed cymbals are the only thing I know of that is above that.

Concerning yourself with what is going on above 10 kHz is a waste of time and energy.

Also, most adult males have significant hearing loss above 10 kHz.
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...Concerning yourself with what is going on above 10 kHz is a waste of time and energy...
I can't agree with this statement at all. The OP is hearing a problem, you just can't ignore that.

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post #7 of 21 Old Today, 08:59 AM
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Originally Posted by Russ69 View Post
I can't agree with this statement at all. The OP is hearing a problem, you just can't ignore that.

Read it again; he is MEASURING a problem, not hearing it.

HE SAYS: "the loss is not noticeable to my ears"....
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Read it again; he is MEASURING a problem, not hearing it.

HE SAYS: "the loss is not noticeable to my ears"....
Thanx I stand corrected. On re-reading I see his measured problem is above 16khz, definitely less serious.

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post #9 of 21 Old Today, 09:49 AM - Thread Starter
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Originally Posted by commsysman View Post
Also, most adult males have significant hearing loss above 10 kHz.
Really? It took me a while to notice the slightly higher frequencies between a 192kbps MP3 and the original source. I can definitely hear some frequencies above 16 kHz, even though what I listen to it on isn't exactly the best when it comes to sound quality.

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Originally Posted by commsysman View Post
Read it again; he is MEASURING a problem, not hearing it.

HE SAYS: "the loss is not noticeable to my ears"....
Correct. As stated before, I can't really hear the loss under normal volume levels. It would probably be a different story if I had the volume cranked up on an high end amp with a good pair of speakers attached to it. Even if I can't hear the degraded frequencies in the left channel at all, it would still be beneficial to someone who could.

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post #10 of 21 Old Today, 10:10 AM
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...Even if I can't hear the degraded frequencies in the left channel at all, it would still be beneficial to someone who could.
There is no good reason to degrade the music source if you don't have to.

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We are well into the 21st century. Why are you still bothering with tape?

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post #12 of 21 Old Today, 11:16 AM
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We are well into the 21st century. Why are you still bothering with ANALOG tape?
Fixed it for you.

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post #13 of 21 Old Today, 02:11 PM - Thread Starter
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We are well into the 21st century. Why are you still bothering with tape?
Not everything was ported over to a digital format. There is still lots of good music out there on older formats that will never be commercially re-released on CD or as a digital file.
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post #14 of 21 Old Today, 02:43 PM
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Not everything was ported over to a digital format. There is still lots of good music out there on older formats that will never be commercially re-released on CD or as a digital file.
That's right but you can convert it to digital and store it anywhere, even back to digital tape!

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Fixed it for you.
And with HDD storage, why would you bother with digital tape? It still has alignment and wear problems like analog tape.

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Originally Posted by snowdog 88 View Post
I recently caught the issue while transferring some records over to my computer. (I use the record level knobs on the deck to control the output volume to my computer to prevent clipping/distortion).
This is why I asked about the cabling - it reads as if you're using the tape deck for variable input to your sound card? If so, are you using composite (rca) L/R channels to your sound card?

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post #17 of 21 Old Today, 06:24 PM - Thread Starter
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This is why I asked about the cabling - it reads as if you're using the tape deck for variable input to your sound card? If so, are you using composite (rca) L/R channels to your sound card?
Yes. Actually it's a RCA to 3.5mm phono jack cable.

The deck has individual knobs for both channels. They are set accordingly so that both channels are close to the same level. I can also verify the levels by looking at the VU meters on the computer and recorded waveform. If I feel that one channel is softer than the other, I can amplify that individual channel during editing. I don't think that this has anything to do with the frequency response.

I also want to note that Dolby noise reduction is turned off during tape transfers as well as the tape selector being set to normal to avoid the loss of the higher frequencies.

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post #18 of 21 Old Today, 06:36 PM
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So I'm still a little confused. Are you passing through the tape deck from your TT then going to mini jack to (I believe) microphone in? Or recording to tape from TT then to mini jack?

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So I'm still a little confused. Are you passing through the tape deck from your TT then going to mini jack to (I believe) microphone in? Or recording to tape from TT then to mini jack?
I'm passing the audio through the tape deck to the line in on my sound card. (Not recording directly to a tape).

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post #20 of 21 Old Today, 07:28 PM
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There are other (better) ways to cap vinyl to hard drive than what you describe. Here is a recent thread What Do I Need to Digitize Vinyl LPs? Ask the Editors

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post #21 of 21 Old Today, 08:46 PM - Thread Starter
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There are other (better) ways to cap vinyl to hard drive than what you describe. Here is a recent thread What Do I Need to Digitize Vinyl LPs? Ask the Editors
Sadly, I have to work with what I got. This is the way I've been doing it for some time now and the results have been satisfactory. I don't consider myself to be a hardcore audiophile, so stuff like recording at a high frequency rate (above 44 kHz) or using a top-of-the-line turntable are not that important as long as I get good results. As I stated before, I can hear frequencies above 16 kHz, but I doubt that I can hear anything past 22.5 kHz. (Maybe up to 19 kHz if I'm lucky). Therefore, I would like to have my recordings reach 22 kHz as anything higher would just waste disk space if I can't hear it anyhow, and the RCA cable method along with the tape deck was doing just that before the frequency loss in the left channel. Even though recording above CD quality isn't a high priority, I am picky about other factors such as equalization across all bands as well as the dynamic range of the music, and my turntable/preamp seems to handle that well. Some other factors also include playback at the right speed and setting the head at the correct azimuth when transferring cassette tapes. All my master recordings are saved as lossless wave files and not lossy formats like MP3.

But we seem to be getting off topic here. Lets get back to the tape deck itself as the frequency problem lies there.

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