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Tape format and speed

Discussion in 'Tape' started by Frank Sch, Dec 1, 2018.

  1. Frank Sch

    Frank Sch Member

    Messages:
    54
    Newbie here. :)

    I understand that the higher the speed, the better the music quality. But less music recorded per length of tape.

    I understand that the wider the format (2 track vs 4 track) the better the quality. But less music recorded per length of tape.

    Best quality from 1/4inch tape therefore, is obtained with 15in/sec on 2 track.

    But to increase music time, which gives better quality:

    2 track running at 7 1/2, or 4 track running at 15in/sec?

    I'm guessing the latter gives better quality, with all fullsizeoutput_1146.jpeg else being equal.

    Learning, Thanks!
     

     

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  2. Chip Chester

    Chip Chester Super Member

    Messages:
    1,986
    Location:
    Central Ohio
    Probably right, but never had the right deck to try it. (Never ran across a 15ips quarter-track recorder.) Made many a 15ips 2-track master, though.
     
  3. dhnash

    dhnash Well-Known Member

    Messages:
    553
    Location:
    Wildwood, MO
    The Technics RS-1506 would be one example.
     
  4. Frank Sch

    Frank Sch Member

    Messages:
    54
    I bought this A77 last summer and have been both saving money for the refurbishment and finding a tech. Just delivered it to him and he reported that this one is a 4-track format modified to 7 1/2 and 15ips. I like the high speed feature paired with twice the recording time of 4-track. Fingers crossed that whoever did the modification did a thorough proper job. Apparently some sound cards also need modification or exchange?
     
  5. GPS16

    GPS16 Well-Known Member

    Messages:
    699
    Location:
    UK Manchester
    Hi Guys,

    I have always had the view that a 4 track running at 15 IPS is a waste. We are talking 4 track as in flipable to side 2 and not 4 tracks at once!!

    To me 15 IPS is worth the tape expense at 2 Track only. The speed gives the quality, the track width gives a lower noise floor. Also if I have a quality 15 IPS recording, the bleed through from the opposite sides tracks are a real downer. The problem does not exist with 2 Tracks.

    I have a 4 track Revox A700 and if a tape is at any of the 3 speeds, the cross talk between sides is evident. Try a heavy rock program on side 1 and then a classical piece on side 2. The classical side will be ruined at the quiet sections, which are common in classical programs, are marred by the thump thump from the other side. This is an issue on the A700 and also my B77 so it is not an alignment issue. Also the HiFi the machines are running on tend to miss nothing. That is what I have payed much for over the years. Whilst a tweak of the head alignment may reduce the problem it will not eradicate it!!! There is always a spec for the crosstalk which is way worse on the 4 track format.

    So for me, run of the mill stuff is 4 track 3.75/7.5. Quality stuff is 2 Track 7.5/15. There are exceptions but it is pretty much how my recordings go.

    Again, personal opinion only. I am in no way stating that this is how it must be!!!

    Cheers.

    GPS16
     
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  6. Frank Sch

    Frank Sch Member

    Messages:
    54
    Always interesting for a newbie like me to hear the opinion of those experienced with R2R. Thank you. Can't wait to build up my own experience/knowledge base on this.
     

     

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  7. twiiii

    twiiii Addicted Member

    Messages:
    6,349
    Location:
    west Texas
    Running at 15 ips, 2 trk allows full spectrum recording at high levels. Recording at 7. 1/2 ips reduces your HF dynamic range by almost 10 db, depending on what tape you use and changing from 1/2 trk to 1/4 trk can cause you to loose another 6db of dynamic range. Revoxs are a very special case in that the HF frequency response doesn't demolish that much when changing from 15 to 7 1/2 and even 3 3/4 can be acceptable, but only with High output low noise tape. I prefer 7 1/2 2 trk with my B-77 to reduce tape drop output, when I recorded music back in the late 70's, but I used professional DBX noise reduction to increase signal to noise and reduce modulation and asperity noises. Before DBX I used my Professional Ampexs with AME Equalization to pick up an additional 10 db of signal to noise above 2.5 Khz or so running Scotch 203 or 201 , but when Maxell introduced UD tape another magnitude of performance was gained over the Scotch. Ampex heads have wider gaps so the frequency response drops off sooner than a Revox, but the Ampex machines can put more level on the tape and take it off with lower distortion and increased dynamic range. During that period of time before digital Signal to noise was the most important specification. The Japanese thought it was reaching that area above 16 kHz as the most important spec. I'll take a quiet recording every time over one with a few extra HF notes..

    Back in the 60's Everyone was amazed when Ampex developed a machine that had 70 db signal to noise below 1 % distortion. That gave us 76 db signal to noise by older NAB standards and close to 86 usable dynamic range. By the 80.s with the new high output tapes we picked another 4 to 6 db of dynamic range. So if you could make the final mix correctly before putting it on the tape and then used that tape to drive the record cutting machine you could almost equal Direct to disc recordings. I said almost. Digital recordings meant you could make multi channel recordings , mix them down later, add effects, and make multiple tapes to drive the recording lathes without introducing any noise, something analog couldn't do. But if you have ever heard an analog tape made with Professional Dolby or DBX, you'll scratch your head and ask your self what's the big deal with digital. There was a quality below 1000 HZ that digital never really captured in my opinion. Yes it was a coloring, but its what you heard at a live un-amplified concert. Something that's missing today most of the time.
     
  8. Frank Sch

    Frank Sch Member

    Messages:
    54
    So how does 1/4 track at 15ips compare to 1/2 track at 7 1/2ips? They both hold the same amount of music per reel, but which delivers the better (not best, I understand) music quality?
     
  9. Skylab

    Skylab Altimeter reading zero Subscriber

    Messages:
    5,438
    Location:
    Chicagoland
    My opinion is 7.5 ips 2-track is superior to 15 ips 4-track, although both sound fantastic!!!
     
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  10. GPS16

    GPS16 Well-Known Member

    Messages:
    699
    Location:
    UK Manchester
    Hi Frank,

    here is one where the material would be the influence to me. For a classical piece which would have quiet sections it would be 7.5 IPS 2 Track without a doubt. Lower noise floor and no crosstalk from side to side. If it was Oasis then the 4 Track at 15 IPS would be a better option as the VU meters would not spend much time below -10dB. Noise or crosstalk on loud programs such as this would not be noticed.

    Silent silence is also part of a quality recording to my mind! This also where the quality recorders show their mettle. On an A700 the tape is not muted in stop mode. If the volume is cranked up there is a pronounced hum, until you give the pinch wheel a shove. This lifts the screen in front of the playback head and the hum is reduced pretty much totally. The extra mechanics to operate the screen are well worth the effort in the machine design. Another one of the reasons that these machine are still sort after and why they hold their value. They were built to perform and they do exactly what is said on the tin!!! The specification values are always worst case. If they are not met with ease you are looking for a fault or a re cal.

    I have been under the hood of 3 different models of Revox machines and I have liked what I have seen in all cases.

    They are a pleasure and it is a privilege to be able to listen to one. As time is going on the TV content is getting lower and lower in standard. We are being fed the same formulaic programs over and over again. My HiFi is now getting more and more use by the year.

    It will now be on again with a good book and a glass of wine.

    Cheers. (literally)

    GPS16
     

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