Reel to Reel 2 track Question

[Tarheel]

I have a few quarter track decks and am considering a 2 track machine. What are the drawbacks if any other than recording in one direction only. I know a little about my decks but nothing at all about 2 track decks. I would be getting a deck with 7.5 and 15 ips speeds and a lot of professional features. What about playback of 1/4 tapes...any problem? What do I need to know before I make the leap?

Chuck

[jcmusic]

Chuck I have a Revox B77 MKII 2 track stereo recorder, it's the slow speed one. Other than not being able to flip the tape over and continue recording or playing, I can't think of any other real drawbacks. My personal feeling is that a 2 track machine is a little more sensitive than the 4 track ones, simply because of the tape width.

Jay

[Tarheel]

Thanks Jay....Do you have to use special tape or is any 1/4 inch tape okay? I assume I can play back my existing tapes on both sides..just flip them over? As I said I am completely ignorant about 2 track decks but I have my eyeon a nice Tascam.

Chuck

[WMcD]

I was around for some of the days of tape but I defer to the experts here, of course.

Any 1/4 inch tape will work with either system. But I read that it is becoming difficult to get. The last factory shut down but then made a last batch. That may have changed. You can Google as well as I.

There is a non compatability between two-track stereo and four-track. I'm not sure that the numbers below are exactly correct when I assign numbers to tracks, but the overall thought applies.

Of course on two track stereo, the head writes on just the left and right half of the ribbon of tape. Generally corresponding to the left and right channel of program sound. So we have the tape divided into 1/2 tracks.(If you flip the tape over, you will hear reverse sound).

On four track we have, naturally, physical track 1, 2, 3, and 4 (each 1/4th of the tape width). On the first pass the signal is put down on tracks 1 (left channel of sound) and 3 (right channel of sound). The gaps in the head are in those location. Then flipping the tape over, the same geometry of the head writes to 2 (left channel of program) and 4 (right channel of program). The head doesn't move, it is just the new geometry.

But as you can imagine, a two track (half track) system is writing its left program to what would be tracks 1 and 2 in a four channel system and its right program to what would be 3 and 4.

Why this is I'm not sure. It is probably because in the early days, it was considered difficult to make a single tape head for two writing gaps, 1/4th of the tape width, with gaps side by side. Spacing them made it more easy and reduced cross coupling.

= = = =

It is my recall that the Philips 1/8 inch cassette stereo system (what we know as cassette, generally) works differently. They had a working mono system which put down mono half track, and then you could flip it over and write (and read) to the other mono half track). There was a 1/4 inch tape reel to reel system like this too.

But when the Philips system went to stereo, I think they put down left and right program on tracks 1 and 2, and this corresponded to their mono system. So their 4 track stereo was compatible with their two track mono.

There was no movement of the tape head.

I point out the cassette system to illustrate what makes various systems compatable or not.

- - - - -

The Lear system of "carts" had some variations too. It was very cludgy where there was an endless loop of tape which wound on to the outside and unwound off the center. Tape was alway slipping against itself in the single reel and I recall there were graphite element to lubricate it (???). So there was no flipping over. The 8-track version is the most well known. However, there were single track versons and half track versions. I really don't know if the 8-track version used staggered tracks. As bad as this was, it was the first mass produced tape for cars.

In this system, the tape head did have to be moved over, mechanically, to go to proper one of the four pair of tracks. I recall there was a metal portion of the loop which would trigger it. But this meant that an "album" would be cut up to four somewhat equal length sections. After a couple songs there would be a clunk where tracks were switched.

Best

[pauln]

http://vsg.cape.com/~pbaum/magtape.htm good source of information on this...

[LarryC]

"Why this is I'm not sure. It is probably because in the early days, it was considered difficult to make a single tape head for two writing gaps, 1/4th of the tape width, with gaps side by side. Spacing them made it more easy and reduced cross coupling"

Gil, I, too, recall that as one of the reasons. Another probably was to allow half-track tapes to be played back in stereo by quarter-track machines, i.e. the left channel half would be picked up by the QT's track no. 1 and the right half by the QT's no. 3. I have one half-track sterero prerecorded RTR tape that is very playable on a QT machine and sounds great. Naturally, it can't be played in reverse, and the signal to noise ratio is reduced without a half-track stereo head although it wouldn't have reverse-channel spillover. As I know you know, flipping the tape over technically means means flipping it end-for-end, and there isn't another, separate "side" to play.

Larry

[jcmusic]

Chuck you can use any 1/4 in. tape ok, but you can not just flip it over and play the other side. If you flip it over it will play in reverse, that is the only drawback that I am aware of. I had both 2 and 4 track decks, I sold the 4 track and kept the 2 track; because I belive them to reproduce sound a little more accurately. Also they have more dynamic range from top to bottom. You can still get new tape if you so choose too, there are a few places that still sell it. I use either Revox or Quantgey tape, which depends on how the unit is biased.

Jay

[WMcD]

Thanks for yours, Larry.

I had not considered what you describe. The staggered four track system could listen to two track recordings. So the four track standard was backwards compatable.

There is another thread running about master tape recordings.

For what it is worth, I recall that in the late 60's and early 70's some popular music was published on four track. At about the same time, the RTR systems were coming on line as consumer items. Hardware and software went hand and hand.

It looks to me that the mass market got distracted with ferrichrome cassettes and Dolby. then CD was on the horizon.

Gil

[Mallette]

My recollection seems different. Playback of 4 track tape on a half track deck will yield tracks 1 and 2 or 3 and 4. So you get one channel forward and another channel backwards given the 1&3 or 2&4 standard for 4 track. OTOH, you can playback half track stereo on a 4 track deck, though with reduced SN as you are only playing half each half track at a time plus the gap (if that makes sense).

Half track always has a slightly better SN as you are using greater tape width for the same signal. Also, there is no possibility of crosstalk, though better 4 track decks exhibited hardly any to start with. If I were getting back to R2R, I'd go 4 track with DBX fixed 2:1 compression. You get CD-level dynamic range and an SN almost as good with all the nice aspects of analog to boot.

I still have a few commercial 4 track reels, the most notable (and valuable) being "Meet the Beatles" on Columbia.

Dave

[Tarheel]

Thanks Jay, Gil, Pauln, Larry and Dave...very helpful information. The reason I am considering the 2 track is that I wanted to upgrade to a more professional deck...one that is rugged and made to withstand studio use though it will just be a home deck. I was hoping for a little increase in sound qualty as well. I was surprised to learn that the Tascam BR-20 is still being made and a lot of the earlier ones are being pulled out of Colleges and government facilities during equipment upgrades. I think they are around $3000 but you can often find them used. I wonder about availability and cost of parts on other 2 tracks. Also learned from a forum I stumbled on that Ampex recorders are tube based and very desireable.

Anyway...thanks for your help guys.

Chuck

[jcmusic]

Chuck there are alot of parts around for the Revox, in case you were wondering. Give me a little time and I will show you some pic's of mine.

Jay

[Travis In Austin]

Tarheel,

Other then burning through twice the tape, 4x if you use 15 ips, there are no draw-backs. The wider track width on two track yields better S/N ratio then 4 track. The 15 Ips speed yields better freq. response. You CAN PLAY A 2 TRACK MACHINE ON A 4 TRACK MACHINE just fine, but you do not get the optimal playback. The 4 track play back heads happen to catch 1/2 of track one and 1/2 of track two. So you are not pulling up the entire track, but for occasional play back you hear everything fine, you are just not getting the full advantage of two track. There are two track machines, Otari, Technics, etc., that are high speed (7.5 and 15 ips) that have two track record heads and two and 4 track playback heads. That allows you to record in higher resolutoin but play back either way. As said before you CANNOT play a 4 track back on a two track deck. Even turning down one channel and running the other in mono will not help because in each channel you are picking up one half of the track going in the correct direction and one half the track going in the wrong direction. Tracks work like this on a four track deck:

Track 1 goes in this direction >>>>>>>>>>>>>

<<<<<<<<<<<<<<<<<< Track 2 is recorded in the opposite direction

Track 3 goes in this direction >>>>>>>>>>>>>

<<<<<<<<<<<<<<<<<< Track 4is recorded in the opposite direction

When you play a two track on a 4 track head the Track 1 picks up on half of of track 1 of the 2 track tape, and Track 3 picks up 1/2 of track 2 of the 2 track tape.

There is no need to worry about getting new tape, as long as you have the money. Quantagy is taking there very last orders and you need to place an order for that rightway through a dealer if you want anymore Quantagy. However, ATR is taking over that company and will be rolling of tape sometime in the future. BUT Emtec in making tape again in the Netherlands and it is readily available all across the U.S. but be prepared for 35 to $40.00 or more per reel vs. $11.00 for a 10" pancake of 456. So if you have empty flanges around you want to buy as many pan cakes as you have flanges. Pancakes come in boxes of 10.

Revox parts are readily available and there are a number of Revox repair facilities, there is a great one in TN. You can buy a brand new Otari 2 Track machine if you have the money, they still make them, and it will last you probably 25 to 50 years of home use. They are designed to play everyday all day.

Hope this helps,

Travis

[Travis In Austin]

Dave is correct about the playback, 4 track tape or 2 track machine noway it is going to happen, 2 track tape on 4 track machine, no problem, you just don't get the benefit of the better S/N b/c you are only picking up 1/2 of each track.There is cross-talk on a two track machine, but, as Dave said, only slight better the high quality 4 track machines. Lower head gaps on higher quality heads allowed for this.

Dave,

We will have to share pre-recorded R2R sometime and compare to vinyl. I have about 200 Rock PR r2r, about 50 Jazz, and some misc other stuff, opera, classical. I even have an E.Power Biggs play Bach for Organ you would probably love. I think it is 7.5 ips. Let me know if you are ever going to be in the Ausin area, would love to have you over.

You have talked about DBX before and I asked you a question if it was a DBX 4 and you liked the 4. I have the DBX NR with the seperate section for DBX encoded vinyl but never tried the 4. If that what you were refereing to when you talked about 2:1 compressoin, on the 4?

Travis

[Mallette]

Totally correct. What I said about getting one in one direction and one in the other when playing 4 track tapes on a half track deck was the result of faulty neuronic connections. However, now they are firing I also remember that the outer track is always a bit lower than the other due to a wider gaurdband on half track than quarter. Noise is definitely higher, though tolerable. Neither then nor now would I record without DBX. It is no more intrusive than RIAA and the benefits are noise levels below audibility even on quarter track and a dynamic range audiquate for almost anything.

In spite of the gaff about the tracks, I've used many miles of various tapes on everything from a Maggie (MagneCord) to Nagra as a broadcaster and audio engineer over many years, but even then I was always ready for new technology. These days, I've no interest in dealing with open reel when I can use very high digital sampling rates to achieve the same end.

Dave

[Tarheel]

Thanks Travis...I don't know if I want one if I can't playback back my 1/4 tracks. Its just there were some very good looking machines on ebay yesterday and I got the urge. The Tascam BR-20 or 3030 caught my eye. The BR-20 is still being made I understand. I have all the tape I probably will ever need....I bought a box of almost new Maxell tapes on ebay from a woman whose husband had passed away. There were 53 tapes including blanks and he never wrote on the boxes and kept the tapes in their plastic bags. Don ended up being the low bidder on the Teac 3300 SX.

Anyway I appreciate your help.

Chuck

[Travis In Austin]

Thanks Travis...I don't know if I want one if I can't playback back my 1/4 tracks. Its just there were some very good looking machines on ebay yesterday and I got the urge. The Tascam BR-20 or 3030 caught my eye. The BR-20 is still being made I understand. I have all the tape I probably will ever need....I bought a box of almost new Maxell tapes on ebay from a woman whose husband had passed away. There were 53 tapes including blanks and he never wrote on the boxes and kept the tapes in their plastic bags. Don ended up being the low bidder on the Teac 3300 SX.

Anyway I appreciate your help.

Chuck

Chuck,

There are several decks that will allow you to record in two track, and PLAY BACK in both two track and four track. They have two sets of playback heads. The Technics RS deck in an incredible deck, I am not sure if it is the 1500 or 1506 that plays both. Also Otari is a great deck that comes in this configuration.

I don't believe the BR-20 has 2 and 4 track playback. It is an incredible deck, the best part about it is that the tape path is the easiest on tape of any deck. Steve Hoffman, the famous mastering engineer uses a BR-20 to play back all master tapes prior to remastering. He then remasters on an Ampex tube 350.

Travis

[LarryC]

Half track always has a slightly better SN as you are using greater tape width for the same signal. Also, there is no possibility of crosstalk, though better 4 track decks exhibited hardly any to start with.

While quarter-track crosstalk apparently is very low, at least on tapes recorded on a good machine, there can be plenty of audible "reverse-channel spillover" on those old commercial pre-recorded quarter-track tapes. It's very annoying in quiet passages to hear low rumbly echos playing in reverse.

Larry

[Travis In Austin]

Larry,

A lot of times the cause of what you are talking about is the width of the sides of the reel. Metal is usually much thiner then plastic reels. Most recorders come with shims to account for this difference in thickness. Otherwise it is a difference in head alignment.

Travis

[Mallette]

Travis:

Mein Gott, I would LOVE to hear that Biggs. I've a major collection of E. Pluribus. Need to find an excuse to get to Austin. I'll bring my "Meet the Beatles" R2R.

You're confusing DBX Dynamic Range Expansion with DBX noise reduction. The noise reduction was adopted en masse as it had no audible impact or twiddle factor (like Dolby A) and provides exactly double the signal to noise and dynamic range. It is a fixed 2:1:2 compander. The disc system was a similar fixed compression designed for LP's. Worked like a hose, but never took off due to expense and lack of interest on the part of the majority of buyers. No way to make it compatible... Discs sounded HORRIBLE encoded and played without it.

The dynamic range expanders are variable DBX. Handled with a bit of skill they can provide a 20 db or greater improvement in SN and dynamic range for LP playback. However, to use them well one really has to have a sense of the original compression...too much and it sounds unstable. Impact restoration, another circuit on the later DBX DRE units required even greater finesse...but when set right along with the DNE, LP's have all the smooth beauty and warmth of analog along with the dynamic range and punch of digital.

Dave

[LarryC]

A lot of times the cause of what you are talking about is the width of the sides of the reel. Metal is usually much thiner then plastic reels. Most recorders come with shims to account for this difference in thickness. Otherwise it is a difference in head alignment.

Huh! Does this mean I should have the heads aligned for plastic reels? Thanks,

Larry