Top or bottom, left or right?

[ofajen]

In case it ever comes up, there is, of course, a standard for which tape head channel corresponds with which channel of audio. I didn't know for sure, so I called JRF, and John confirmed my guess, which was that track 1 is the top channel, the one farthest from the deck plate. This is apparently the standard from mono to 40-track.

Normally, I don't have to worry about such things, but I'm wiring up the erase head on my M-23. I guess as long as I have erase, record and play all the same, I would have been OK, but I'd rather have it follow the standard, too.

Cheers,

Otto

 

[ethyrvalve]

my M-23

sweeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeet!

Thanks for passing along this info too. I was curious about this myself.

 

[ofajen]

sweeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeet!

Thanks for passing along this info too. I was curious about this myself.

I'll post some pics once the M-23 is actually operational. The transport was unmounted in standard rack width. The stock console version is much wider. I built a little roll around console for it, with the transport on top laying flat and the electronics mounted down below and in front, and it's low, so that it's comfy to operate it sitting down.

The transport is about the same size and shape as my Teac A-3340S, just with width and length reversed. I pulled the sides and back covers off the Teac and built a similar roll around console for it, with the Teac laying horizontally on top of the console, so they kinda match.

I'd like to have an M-23 four-track, too. For years, I've been trying to buy Mitch Easter's portable M-23 four track, but he won't sell it. It came from CBS records, so it had some nostalgia value, but the situation has gotten much worse: now one of his close recording associates always uses it when she records. They do the old-school 60s thing where you track on a four track, then play parts live while dubbing to another four track. I think I'm going to have to come up with another option...

Cheers,

Otto

 

[sweetbeats]

I've always thought of it that way without really thinking about it since, in English, we read from top down, but yes I also appreciate knowing the definitive answer, and of course Mr. French would be definitive.

Hey, Otto, sure would like to know more about your M-23 at some point...those 3M transports are really neat...how many tracks is your M-23 setup for? The M-23 preceeded the M-79 right? But the M-23 is a capstan-less closed-loop transport like the M-79?

 

[ofajen]

I've always thought of it that way without really thinking about it since, in English, we read from top down, but yes I also appreciate knowing the definitive answer, and of course Mr. French would be definitive.

Hey, Otto, sure would like to know more about your M-23 at some point...those 3M transports are really neat...how many tracks is your M-23 setup for? The M-23 preceeded the M-79 right? But the M-23 is a capstan-less closed-loop transport like the M-79?

The "top down" rule applies for audio. If any of us care, instrumentation recorders number from the deck plate up.

My M-23 is two track. As a small format version, it can be either 1/2" or 1/4". I could set it up as a 1/2" two track or buy two more channels and set it up as a four track which would actually be cheaper. My plan is to keep it as a 1/4" two-track.

The M-23 was the first series that was generally marketed. There was a 1" large format transport that was typically 8-track. That was Townsend's home rig for a while and also used a bunch at Abbey Road in the late 60s. I suspect my transport was built around 1959, due to the low serial number.

The M-23s use rim drive. The next series was the M-64 small format and M-56 large format. They used belt drive, but the same cards as M-23s. I have the parts to convert this M-23 from a 15/7.5 rim drive to a 30/15 belt drive, but haven't installed them, because the rim drive works fine and 15 ips is pretty much what I use.

The final series (starting in early 70s) was the M-79. One big card per audio channel. Still belt drive, but with a DC capstan motor that can do Varispeed and sync up. All the earlier models use AC sync capstan motors.

None of the 3Ms are capstanless, but the capstan is 2" diameter and drives the tape into the loop in one side and out of the loop on the other.

Mitch just shot back to mention that he has another M-23-2 I can have. I traded it to him a while back for a Gibson amp and Gibson guitar, but then Otho Wilburn kinda disappeared while this M-23, my Auditronics console and a bunch of Mitch's other stuff was in his care. It all resurfaced when Matt Allen found it (some of you may recall this tale from about a year or two ago, I think) but Mitch tells me the M-23 suffered somewhat and is now best fit for parts, not restoration.

Cheers,

Otto

 

[sweetbeats]

Oh, cool.

Thank you for the info.

MAN...! You'd never suspect the M-23 is that vintage by looking at pics of it IMHO...ahead of its time I'd say.

Hm! I thought the M-79 was capstan-less...that makes sense that it is not...so the capstan "shaft" is the roller at the top of the loop and that's a counter roller at the bottom?

Really neat.

 

[ofajen]

Oh, cool.

Thank you for the info.

MAN...! You'd never suspect the M-23 is that vintage by looking at pics of it IMHO...ahead of its time I'd say.

Hm! I thought the M-79 was capstan-less...that makes sense that it is not...so the capstan "shaft" is the roller at the top of the loop and that's a counter roller at the bottom?

Really neat.

Right, the reversing idler in front did double duty for the counter in the M-79s.

Yeah, nobody was even close for a decade when it came to flutter and especially that annoying audio band scrape flutter until Stephens used 3M transports and eventually designed his capstanless system. Mitch sold his Stephens 16 track a few years ago and now it's half as far away, so that's also a machine I may try to acquire and fix up.

Cheers,

Otto

 

[lo.fi.love]

[...] I built a little roll around console for it, with the transport on top laying flat and the electronics mounted down below and in front, and it's low, so that it's comfy to operate it sitting down.

Otto,

Can you please post a picture of this?

I'm considering building something like this for myself, and I'd like to see how you did it. I might ask a couple questions about the design, too, if you don't mind.

 

[ofajen]

Otto,

Can you please post a picture of this?

I'm considering building something like this for myself, and I'd like to see how you did it. I might ask a couple questions about the design, too, if you don't mind.

Will do. Might be a couple of days. Right now the front panel is off and the transport is jacked up in front with a board so I can work on the underside of the cable connector to fix up the erase head wiring.

Cheers,

Otto

 

[dodgeaspen]

Thanks for the post. I would like to see some picks of this beast when you get the time.

 

[ofajen]

A quick update: I did get the M-23 wiring complete, so the transport is back in place. I've had some frustrations getting the thing aligned, mainly on the record side and I think I may have an issue with the height of one of the incoming tape guides relative to the heads, so I'll need to deal with that before things will be happy on the electronics side.

It's also a bit of an adjustment dealing with the M-23 controls. The cards are basically the same ones I'm familiar with from the M-56, except designed for a 15/7.5 NAB machine instead of 30/15 NAB machine, but the cards are in separate racks and the controls for metering and monitoring are set up a little different.

Hopefully, progress will come at some point. More later, including a few pictures!

Cheers,

Otto

 

[ofajen]

Here are some links to pictures of the M-23 in its little console....

I haven't taken the time to paint the console yet. I'm thinking of painting it a coffee brown color, or maybe black.

Notice the groovy Peanuts trash can on the left in the 3/4 view!

Cheers,

Otto

 

[sweetbeats]

Good grief! Thats a groovy looking transport!

That thing has some serious style! Those VU meters are huge. Are the electronics tube driven?

You probably said this already but I'm having a hard time determining if it is a 1/4" or 1/2" transport....the heads look like 1/4", but the rollers look like they are for 1/2"...

Wow. Cool! Keep it coming!

 

[ofajen]

Good grief! Thats a groovy looking transport!

That thing has some serious style! Those VU meters are huge. Are the electronics tube driven?

You probably said this already but I'm having a hard time determining if it is a 1/4" or 1/2" transport....the heads look like 1/4", but the rollers look like they are for 1/2"...

Wow. Cool! Keep it coming!

Yeah, the meters are pretty cool. They are real 4 1/2" Simpson VU meters, and you can switch between playback, signal, erase and bias signals.

The electronics are all discrete, transistor based, with high voltage supply lines, plenty of headroom and big, high-quality input and output transformers.

The heads are 1/4". As is common in a lot of the pro lines, they made a "small format" transport and a "large format" transport. The small format transport works either 1/4" or 1/2", you just swap in a different head stack plate and adjust or swap tape guides. Back then, 1" 8 track was large format.

Cheers,

Otto

 

[cjacek]

Man, that's a seriously vintage looking machine! Love it!!

 

[ofajen]

More pictures...

The whole mix area:

Covers off of the M-23 while I'm working on the tape path... notice the transport deck plate is milled from 2" thick aluminum... very stable.

Closer views of the channel electronics...

Some shots of the Teac A-3340S in its new console. Voltmeter and oscillator lurk below...

Cheers,

Otto

 

[cjacek]

Man, Otto, I'm taking serious notes on building something like you've done for your 3340S for several of my 4 tracks. Thanks for the photos. Immensely cool setup!

 

[ofajen]

Man, Otto, I'm taking serious notes on building something like you've done for your 3340S for several of my 4 tracks. Thanks for the photos. Immensely cool setup!

Thanks! That's very kind. We have five kids under 10, so I can sometimes find time to tinker on the machines at night, but finding time to work with the table saw, that's another matter! The console for the M-23 is much more precise because I had a bigger block of time to work on it, like two hours. That was my Father's Day present. The Teac one I had to cut the pieces in about 30 minutes, so the fit is not as good. Still, it totally gets the job done. Used up a bunch more scrap wood, too, which is always popular with my wife!

As for the idea, it was partly the thinking process that went into the M-23, which was limited by the length of the cables and my desire to keep it compact and low for sonic reasons. But I simply HAD to do something for the M-23, since it was just unmounted electronics and an unmounted transport.

The idea for the Teac really harkens back to the early 80s in my electronic music course here at the university. Our electronic music prof had this neat studio with an EMu modular synth the size of a wall, a patch bay and lots of tape machines: Tascam 38, Teac A3340S, plus several two track machines, mostly Studers and Revoxes. Anyway, most all the machines were mounted horizontally in some sort of rolling console like these, which is very convenient, IMO.

I've had numerous parts off the M-23 tonight. Had to pull the headstack to adjust the tape lifters. Got that fixed so the lifter is off the tape during playback, but the tape height problem remains and now I'm thinking it's a problem with the reversing idler not being vertical. Not sure how to fix that... Well that's for another day.

The cool thing is that I accidentally found out that the runout sensor and circuit works perfectly. I hit the sensor with a flashlight and the transport shut down! Now I just need to install a tape sensor light and it should work. Only reason it didn't work was no bulb in the lamp socket. The lamp is just an ordinary 28V indicator bulb, so they are cheap and easy to come by. No more having to turn the deck off to change a reel of tape or have it spin frantically when the reel runs out before I can punch the off switch! Cool!

Cheers,

Otto

 

[sweetbeats]

Otto, seriously...this thread has gone wayyyy off-topic, but I'm really glad it did and glad you put up all the pics and detail. NEVER had a chance to see the guts of a 3M deck. REALLY impressive, and I can relate to nighttime tinkering...My wife and I have 4 children 11 and under...not quite up to your situation but I can relate.

How does the reversing idler mount? The rotary guide on the Ampex 440-8 is held to the transport plate by a center bolt, but there are three fat set screws underneath also so the guide actually sits on a fully adjustable tripod. Good and bad but I wondered if there was any adjustability like that on your reversing idler...not that it should need it with a deck plate like that!

Ahh the 3340S...that was my first open reel deck...looked just like yours.

I remember when I first discovered that I needed to be aware of the optical tension arm position sensors on my Tascam 58...had the dress panel off setting tensions and my hand kept making a shadow over the optial sensor. I kept thinking I was seeing something move, and then I realized I was seeing something move: the tension arm.

Wow. This is great. Thanks again, Otto, for taking the time to share...OH! The electronics...yeah those are formidable! I hear what you are saying about the higher voltage. What do yours run on? My 440-8 utilizes 39V rails, also discreet transistor-based units, and there is a very noticeable difference in the power and presence of audio that passes through them.

 

[ofajen]

OK, I lied. I went ahead and tinkered with the idler and got it more nearly vertical. Now the tape line is good and the response is much more hopeful! Decent response out to 16K and still hanging in there at 20K. Time to start over with a full electronic alignment. That really will be after I get some sleep and take the boys fishing with my dad this morning.

Cheers,

Otto