TP-027, Jerry Garcia / David Grisman wins a Writer's Choice Award from Myles Astor of Positive Feedback Online

Author Topic: quad tape ?  (Read 4460 times)

Offline wcb

  • Newbie
  • *
  • Posts: 4
    • View Profile
quad tape ?
« on: August 11, 2008, 05:54:36 AM »
Can I playback a quad tape on a 4 track mach?  It a Q4 tape 
wallace bowden
bottlehead technics 1500>seduction tape preamp>vip scoutmaster>benz ruby3>ear phono preamp>audioreasearch pre&amp with phono>proac d15>charter subscriber 28

Offline ironbut

  • Global Moderator
  • leader in spreading disinformation
  • *****
  • Posts: 2503
  • rs1500>repro amp#1
    • View Profile
Re: quad tape ?
« Reply #1 on: August 11, 2008, 10:52:51 AM »
You can't play a quad (4channel) tape on a 1/4 track machine. You'd need a 4 channel deck with a 4 channel head. A 1/4 track machine has 2 channels (stereo) of record/playback electronics (amps) and a 2 channel head. Picture a head standing upright so the tape is traveling across it from left to right. The head surface is divided into channels in stripes that are also left to right.  So if you were playing a 1/4 track tape, it has 4 tracks and the "side one" stereo pairs left channel is also at the top of the tape. So when you finish listening to side one, you move the full reel from the right reel turntable (take up reel) to the left turntable (supply reel). But what you're doing also is flipping the tape. That puts the left channel of "Side Two" on top. So the tape has 4 channels but two are going in the opposite direction from the other 2.
So, if you followed me there, the left channels are always on the outside of the tape and the right channels are on the inside. So a quarter track head only has 2 working stripes. One at the top and one in the middle (or thereabouts). A 4 channel head has 4 working stripes equally distributed on the head.
If you collect old 1/4 track tapes like I do, the above is the reason that when tapes are damaged, it's almost always worse in the left channel (it's always on the outside and more exposed to damage).
There were different versions of Quad. What I outlined above was for discrete 4 channel. I think that's what Q4 was. Some just required a decoder and a 1/4 track (stereo) machine. I'm not even sure I had all the different versions straight when I was fooling around with it in the 70's. It should say on the box what's required to play these back.
BTW welcome to the forum Wallace
steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline steveidosound

  • Sr. Member
  • ****
  • Posts: 484
    • View Profile
Re: quad tape ?
« Reply #2 on: August 11, 2008, 12:06:05 PM »
All of the facts previously stated are correct as far as I know, but
I am now going to step into it here with all the definitions that got tossed about through the years for pro, semi-pro and amateur formats. You can play a 4 channel tape on a 4 track recorder - that is one like a Teac 3340 for example, that records and plays four tracks in one direction with the aforementioned 4 track head(s).  4 track was typically used as more of a pro term for the bigger machines to do multi-track recording. 4 channel or quadraphonic for the quad (Q4) tapes you mention and their home playback machines. 1/4 track for the standard stereo interlaced 2 channel consumer format that was just mentioned in the first reply, but confusingly the tapes are typically called 4 track because, well, they have 4 tracks  - an interlaced stereo pair running either direction. Another usage of 4 track was to quadruple time mono record a tape using the 2 track either direction for 4 track mono with 4 different programs.
Prerecorded reel to reel tapes were first introduced in the 2 channel  (stereo) 2 track format - a few early ones even with staggered head configuration where the left and right channels were displaced on the tape by a set amount for a few of the first consumer stereo machines that used 2 mono 1/2 track heads next to one another. Again, there is some confusion between 1/2 track mono (consumer) one mono track each direction on each side of the tape, and 2 track stereo which is typically the pro mastering standard at higher speeds (like the Tape Project tapes)
 I did not know if there were any other matrix encoded or carrier encoded quadraphonic systems for reel to reel tapes as there were for vinyl. I just knew about the 1/4 inch 4 channel ones (Q4) and the Q8 variation for four channel "8 track" with 2 four channel programs as opposed to the normal 4 two channel programs on 1/4" tape.
BTW, if you do play a Q4 quadraphonic reel on a 1/4 track machine, you will hear 2 channels of the quad mix (I forget if it would be front left and right or front left and rear left)
Steve Williams

you don't want to know what equipment I listen to...

Offline ironbut

  • Global Moderator
  • leader in spreading disinformation
  • *****
  • Posts: 2503
  • rs1500>repro amp#1
    • View Profile
Re: quad tape ?
« Reply #3 on: August 11, 2008, 04:29:45 PM »
Hey Steve, like I said, I was confused then and I'm just older now. I don't know if you remember the old Quad shows that used to be on the radio sometimes (this was when I was back in Atlanta). Two stations would broadcast two channels each so I used to get together with a buddy and we'd hook our 2 systems up in the same room and bingo, 4 channels. The novelty wore off pretty fast but it was kinda fun.
Anyone who does have an interest in the non discrete version (like Steve said, these were for the most part on lp) and need a decoder, AudioXpress has a book called the Joy of Audio Electronics (if I recall correctly) that has a decoder as one of it's beginner projects. I'm not sure if all the parts are still available new but there it is.
steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline steveidosound

  • Sr. Member
  • ****
  • Posts: 484
    • View Profile
Re: quad tape ?
« Reply #4 on: August 11, 2008, 08:40:15 PM »
At the risk of veering seriously OT here I remember one of those programs from my early 70s High school days of a live concert with 2 FM stereo stations carrying the front and rear channels PLUS video from a local TV station ! This was from San Francisco. I think they did more than one, but the one I remember featured a new emerging artist - Linda Ronstadt.
I had no four channel means of recording the audio then - much less the video.
Steve Williams

you don't want to know what equipment I listen to...

Offline ironbut

  • Global Moderator
  • leader in spreading disinformation
  • *****
  • Posts: 2503
  • rs1500>repro amp#1
    • View Profile
Re: quad tape ?
« Reply #5 on: August 11, 2008, 08:51:25 PM »
Wow, video too! They should do that for guys with home theaters now (of course, now you'd have to pay through the nose).
Linda really knocked a whole lotta socks off in those days. Just wonderful in concert.
steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline docb

  • Administrator
  • leader in spreading disinformation
  • *****
  • Posts: 1345
    • View Profile
    • Bottlehead Corp.
Re: quad tape ?
« Reply #6 on: August 11, 2008, 10:44:30 PM »
Oh yeah, I remember that! I don't recall seeing Linda Ronstadt, but I do recall the process of two FM stations delivering the audio for quad and you watched the show on the one of the local TV stations. Now my brain will be grinding away until I remember what music they played on the broadcast I saw. I want to say it was rock and they did a psychedelic light show thingy for the video on the one I saw. But that was a looong time ago and I may be fabricating...
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline CVila

  • Newbie
  • *
  • Posts: 1
    • View Profile
Re: quad tape ?
« Reply #7 on: August 13, 2008, 08:20:59 AM »
10/04/70 (Sun)  Winterland Ballroom - San Francisco, CA
TV broadcast KQED & FM quadrophonic simulcast KQED-San Francisco & KSAN-San Francisco
Grateful Dead, Jefferson Airplane, Quicksilver Messenger Service, Hot Tuna & New Riders of the Purple Sage
Chris Vargas-Vila

Offline docb

  • Administrator
  • leader in spreading disinformation
  • *****
  • Posts: 1345
    • View Profile
    • Bottlehead Corp.
Re: quad tape ?
« Reply #8 on: August 13, 2008, 08:52:58 AM »
That musta been it. Thanks for reminding me what I was doing on October 4th, 38 years ago.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project