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What's the sound quality differences between 3.5" and 7" per second?

Discussion in 'Tape' started by Onebean, Jun 13, 2018.

  1. Onebean

    Onebean AK Subscriber Subscriber

    Messages:
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    Location:
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    I have Pioneer RT-707 decks, and have only recorded at 7" per second. My goal has been to reproduce the original recording as faithful as possible, for critical listening. A lot of the used tapes I have bought are recorded at 3.5". Is there a big trade off in sound quality at 3.5" per second? I have read that the faster the tape moves, the less tape hiss and drop outs that can be heard. Is this what degrades the sound?

    I'm considering putting a couple tapes together for less critical listening, and it would be nice to double my recording time. Please share your thoughts and experience.

    Onebean
     

     

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  2. BOUXY

    BOUXY Super Member

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    4,651
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    It is 7 1/2" and 3 3/4". My unit you can see in my Avatar sounds quite decent when I record at 3 3/4"
    Your used Tapes you have were previously recorded at 3 3/4 " but by who and on what and what kind of Tape Brand?
    You should try recording on your own machine to see how it sounds and then you might have a better understanding of it all:)
     
  3. phantomrebel

    phantomrebel Serial Tapist Subscriber

    Depends on tape. Some were formulated to maximize quality at slower speeds (e.g. EE types, some BASF, etc).
     
  4. Onebean

    Onebean AK Subscriber Subscriber

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    Location:
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    My bad, yes 7.5" and 3.75". I'll give it a try, nothing lost but some time. I thought I remembered someone posting the science between 7.5" and 15", and reporting there was minimal, if any sound quality difference, and the level of tape hiss was also very minimal, with the final statement being 15" was just a waste of tape for home use. I wondered how that translated to 3.75" vs 7.5".

    I'm particular on the tape I buy. I look for BASF Hi-Fi LP35, and Maxell UD35-90 only. I have a few others that have come my way in package deals, but not too many.
     
  5. smurfer77

    smurfer77 AK Subscriber Subscriber

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    Location:
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    First, you will get best recordings if your deck is calibrated for the tape you use and if you record at an appropriate level - the later will be your biggest factor in recording quality. If you record too quiet you will have hiss and if you record to loud you will have distortion.

    About the tape speeds, every time you double speed you theoretically improve 3dB over tape hiss. Same goes for track width (e.g. 4track vs 2track tapes)... you double the width you get 3dB improvement. These effects are linear and thus additive, i.e. if you double speed and width you get 6dB, or if you quadruple speed you get 6dB.

    There are, however, other more subtle advantages to faster and wider tapes, such as less 'drop outs' and other factors.

    Look, you can make very respectable 3.75ips recordings, if you record well, that will be hard to tell from CD if you don't put your ear close to the speakers. As I mentioned, recording at appropriate level will likely affect your more than doubling the speed, but yes, all things done properly 7.5ips is better than 3.75ips. Whether or not it is worth the extra tape depends on your personal preference and to a large extent, your high frequency hearing response.

    You should try both speeds and see what happens and if it is acceptable for you. Maybe use both speeds.... low speed for long party tapes or all day listening and high speed for 'serious listening'.

    Did I say yet, make sure you record at a good level no matter which speed you use?! :) :) :)
     
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  6. Onebean

    Onebean AK Subscriber Subscriber

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    Smurfer, this is the type of data I was hoping for. Thank you.

    Can you give me a guideline for setting my recording levels?

    My process has been to start the source and adjust the level pot till meters run at the black and red transition (zero db), with the quite passages in the black, and the louder dynamics bouncing into the red. I try to set it so the meters never go above the top of the red. Once I have it set on the first track, I sample most all the other tracks, to make sure I'm not pegging out the meters, making any needed level adjustments.

    Onebean
     
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  7. audiojones

    audiojones Jonesin' for audio Subscriber

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    Recording levels when the machine is set to source are pretty much useless, that's just a starting point. Tape has to be rolling and you've got to be monitoring the actual tape itself as it records to get a proper and accurate level and sound quality check. Depending on the tape you may have to deviate from the source settings in one or both channels, especially with used tape. While monitoring the recording try different bias and EQ button settings too, see which combination sounds most like the source when you flip back and forth between source and tape.

    FWIW I like to FF into the tape a bit, start recording and fool with the controls until everything is just right. Then I rewind, start the recording and monitor it as it goes. That way you have the bias, eq, volume and all that stuff set very close and you won't get large swings or channel imbalances due to volume adjustments.
     
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  8. maxhifi

    maxhifi AK Subscriber Subscriber

    Messages:
    2,850
    Location:
    Edmonton Alberta Canada
    "What's the sound quality differences between 3.5" and 7" per second?"

    On my old Ampex 800, it's like the difference between night, and day with pre-recorded tapes, and is also obvious with home-recorded tapes. I wouldn't pay too much money for any pre-recorded tape at 3.75 IPS, unless you just must have it on reel to reel.
     
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  9. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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    52,454
    upload_2018-6-13_17-12-2.png

    From Stereo Review review:

    upload_2018-6-13_17-15-2.png
    source: https://www.hifiengine.com/manual_library/pioneer/rt-707.shtml

    NOTE: S/N will be worse at 3.75 ips vs. 7.5 ips. Not sure how much worse (3 dB, I think? I am too lazy to google it, sorry) -- nor am I at all sure why Pioneer didn't offer different S/N specs for the two velocities (i.e., I don't really know what their advertised "58 dB" spec means).
     
  10. Onebean

    Onebean AK Subscriber Subscriber

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    Location:
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    Thank you everyone!
     
  11. MaxxVolume

    MaxxVolume AK Subscriber Subscriber

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    All good, solid advice given here so far ! There is one more layer to the cake which has not yet been discussed, but only applies if tapes are to be played back on your machine(S) only.
    What I`m referring to is adding a dbx noise-reduction unit to your system. With one of these, you can produce recordings @ 3 3/4 ips that are just about indistinguishable from a good clean CD (assuming, of course, that you did your part in the process).
    I have this smallish NX-40 unit, it does a nice job. Not expensive, either....

    upload_2018-6-14_13-47-41.png
     

     

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  12. Onebean

    Onebean AK Subscriber Subscriber

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    So do I use the noise reduction unit at record, playback, or both? Do I need a unit for each of my machines to play back tapes recorded with the noise reduction unit?
     
  13. audiojones

    audiojones Jonesin' for audio Subscriber

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    Both. You have to encode it during record and decode it during playback. You need a DBX unit connected to any machine you plan on playing DBX encoded tapes back on. I stopped using DBX because it must be used to play the tape back if it was used to record it and I don’t always have a DBX unit handy when I want to play a tape back on a different machine. I’ve found noise reduction pretty much unnecessary at 7.5 ips, don’t use 3.75 for anything but speech usually.
     
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  14. pdm4606

    pdm4606 Super Member

    Messages:
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    Location:
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    Really...Years ago(1940's-1950's-1960's) tape was an issue as were the electronics, as were the heads and as was the machine in general. Bundling all this together one method to get better performance was to keep speed high as possible. This also sold a lot of tape.
    Now a days things are a bit difference. Heads are better as are the transport methods as are the electronics and finally improvements in tape quality. I can't believe the difference I have seen from the early 60's to now.
    Near studio recordings are easily made with off the shelf components and tape. I used to have a Sony tape only player that was amplified and equalized by my old Fisher KX-100.
    I have recently made recordings on my newer setup that are distortion free and silent way better than the old setup. I should add so are the microphones.
    The same issues hold for cassette.
     
  15. MaxxVolume

    MaxxVolume AK Subscriber Subscriber

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    No need to over-complicate things....if you create a dbx-encoded tape, then you will have to have the dbx unit connected to DE-code it on playback. If you have more than one deck, it is a simple matter to swap the dbx between them....just unplug the RCA cable from one deck, and plug it right into a different one. Maybe a 10 second job, certainly not a BFD.

    As I said earlier, the results are quite dramatic, you can basically record at 3 3/4, while getting results pretty much like 7 1/2. A good way to double your recording time, while maintaining the integrity of the sound quality.
     
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  16. dhnash

    dhnash Active Member

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    Location:
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    Or as an alternative, you could consider using an DBX 200 Route Selector which will allow you to connect multiple tape decks and a single DBX noise reduction unit to it. The single DBX noise reduction unit can then be used for encoding and decoding with any of the decks. The unit also allows any of the decks to be connected to another connected deck for dubbing purposes.

    Details for the unit are available here: https://www.hifiengine.com/manual_library/dbx/200.shtml

    Photos of the unit are available here: https://www.ebay.com/itm/Vintage-DB...074420?hash=item23a31763b4:g:Ds0AAOSwc~xbIJqH
     
    Last edited: Jun 14, 2018
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  17. MaxxVolume

    MaxxVolume AK Subscriber Subscriber

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    Yes, dbx made lots of cool stuff to make life easier for the home-recording enthusiast....with 6 tape decks in my system, keeping track of everything became easier once I incorporated two dbx 400 units, which makes switching between components a piece of cake.

    upload_2018-6-14_17-10-2.png
     
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  18. Blue Shadow

    Blue Shadow I gotta get me a new title

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  19. audiojones

    audiojones Jonesin' for audio Subscriber

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    Location:
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    By “not always handy” I meant when playing them back on a machine other than the ones here ( I actually know a few people locally who still use open reel decks in their system and sometimes we swap tapes back and forth). Also the way two of my systems are set up they are kind of “built in” so it’s a pretty bfd to pull the deck or the preamp out and do a jack swap. Every time I pull a reel off the shelf that I recorded in DBX back in the 80’s I kick myself, plus personally I don’t care for the way DBX 224 sounds even when it’s set up and properly calibrated. Haven’t tried other types of DBX but I don’t like not being able to play a tape on any other machine without bringing along a decoder.
     
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  20. MaxxVolume

    MaxxVolume AK Subscriber Subscriber

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    I can dig it....reel on ! :)
     
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