Converting a 4-track RTR deck to 2-track playback.

Orcinus

Active Member
I have a Teac 3340S (4-track) and an A-3300SX (2-track). The heads on the 3340S are pretty worn, and all my recording has been done on the A-3300SX. Right now I am using track 1 and 4 to play my 2-track tapes. I would like to convert the 3340S into a 2-track machine with a 2-track head(and maybe retain 4-track playback compatibility). I don't plan to record on the 3340S, so I would put the 2-track play head where the existing record head lives, and either use the Simul-Sync switches to select 2- or 4-track playback. However, the monitor amplifiers may be set up different for playing from the record head, in which case I would just utilize the two unused playback amps.

My question is this: Has anyone experimented with using different heads than intended for a particular tape deck? I recently saw a nice Otari 2/4-track headstack go on ebay that I was outbid on, I had intended to use the 2-track head for the mod. (It even came with a splicing block attached to the head cover!) Can I use any 2-track head and simply adjust the playback EQ for flat response? Or would I have to use a head from a similar series of deck from a particular manufacturer, due to extreme frequency response differences?

Any further suggestions/advice is certainly welcome!

Here's a pic attached, too. ;)

decks.jpg


:music:
 
So what you are wanting to do is, mod the 3340S into a play-only machine, having half-track and quarter-track stereo playback?

There's a lot of people who'd love to get their hands on that 3340S to get into 4 track recording. It looks to be in really nice shape, with a lot of good years of service left in it. New heads can still be had from Teac, if the originals are truly, totally shot.

I'd say, getting a new repro head for the 3300S-2T and fitting it into the record head position of the 3340S's head assembly can indeed be done (to do so, you'll have to go with the 'using the other two playback amps' scheme, as the record and play heads of the 3340S have very different electrical specs) but you'd be far better served seeking a deck having repro heads for both formats built-in, like a number of the Otari MX5050 series machines. I expect you won't have to look too far around AK to find someone who'd give that 3340S a good home, and who might either have, or know someone who has, a stereo machine better suited to your requirements. Good luck!
 
Jay Pemberton said:
So what you are wanting to do is, mod the 3340S into a play-only machine, having half-track and quarter-track stereo playback?

Exactly!

Jay Pemberton said:
There's a lot of people who'd love to get their hands on that 3340S to get into 4 track recording. It looks to be in really nice shape, with a lot of good years of service left in it. New heads can still be had from Teac, if the originals are truly, totally shot.

They indeed are on their very last hours of service, unfortunately. :tears: And these are heads I bought on ebay for $50+ some two years ago. I was rather pissed that they were so worn when I got them. (I hardly used the deck at all during the last two years)

Jay Pemberton said:
You'd be far better served seeking a deck having repro heads for both formats built-in, like a number of the Otari MX5050 series machines. I expect you won't have to look too far around AK to find someone who'd give that 3340S a good home, and who might either have, or know someone who has, a stereo machine better suited to your requirements. Good luck!

I have considered selling the 3340S, but at the moment tracks 2 and 3 are so far out of electronic alignment, it would be nearly impossible to recalibrate them without a proper calibration tape from MRL. (The previous owner was using a record head in the playback position, because the original record head was completely worn through the gaps.) I would not feel right selling a deck that's not in full working condition, especially if I cannot provide the means to make it so. Also, from what I've seen on ebay, good 2-track machines are kinda rare, and usually sell for considerably more than what a 3340S would sell for. And don't even get me started on shipping a beast this big. Shipping ain't cheap to/from Canada, eh! :D

Of course, if anyone reading this is willing to take a straight-up trade for a 2-track deck, gimme a shout and we'll see what happens.

:music:
 
Come on guys, my most important question hasn't even been answered yet. Can I use a different manufacturer's head?
 
Are you more concerned about the mechanical aspects (mounting method, dimensions and deviation from the tape path etc?) or the electrical aspects.

If it is the electrical aspects, I would expect the equalization curves to be the same for different heads, there may be some variation in output levels that may upset level sensitive calibrations IF they are present in that machine's electronics.

Usually the playback heads are just treated as voltage sources, and the output is fed to high impedance amplifiers. Sometimes there is some loading to a specific impedance (usually a resistor) and the schematic must be examined for that to be revealed.

For playback only it is a reasonable gamble if the head is mechanically compatible.

Recording heads, on the other hand are far more complex beasts, because of the presence of the inductive component of the head, affecting the loading to the circuit driving the head, and books have been written about the methods to coerce the information fed to it to stay on the tape. And we're not even talking about BIAS being fed into it at the same time (in MOST cases), another can of worms.

Of course my experience with tape recording and playback was with High Speed Tape Duplicators..... in the late 70's....
 
The problem I can see is in the record equalization. You may not have an issue at 7.5 ips, but 3.75 may be an issue. The 3340 has eq for 15 & 7.5 ips running at 1/2 track. Record levels are somewhat higher as well.
About 20 years ago I also looked into this possibility for my A-4300. Decided against it after reading up on it.
 
jblmar said:
The problem I can see is in the record equalization. You may not have an issue at 7.5 ips, but 3.75 may be an issue. The 3340 has eq for 15 & 7.5 ips running at 1/2 track. Record levels are somewhat higher as well.
About 20 years ago I also looked into this possibility for my A-4300. Decided against it after reading up on it.

Neither machine does 3.75 IPS (the 3300SX is the 2-track model, which runs at 7.5 or 15 ips. Only the 4-track model ran at 3.75 and 7.5 ips).

I am not concerned about recording on the 3340, as I will do all the recording on the 3300SX.
 
A couple of other considerations re: 3rd party heads....

If you've got Dolby-ized tapes, then there could be some problems with playback levels. Ideally, you'd be able to adjust the new ones to get sufficient levels so as not to upset the Dolby encoding but still something to think about.

Next, ensuring they'll mount correctly to the head assembly is important from a mechanical standpoint. It needs to contact the tape in the proper planes without the tape fluttering on the head as it passes. I remember mounting some aftermarket heads on some Revox's back in the 70s and just giving up for their lack of proper placement on the head stack. I would hope that today's 'new' heads would be more precision than back in the day due to tighter tolerances in manufacturing.

Lastly, my thought is, if there are Teac heads still available for those machines, I'd be stocking up on them *and* any other wearable parts like belts and pinch rollers. No telling when sources may dry up.

BTW, those pics - which are excellent - bring back fond days of using Teacs for recording bands back in the 70s. I used to covert my room in a boarding house into a studio by nailing the matress and box spring onto the wall and hanging the blankets on the other walls. Made many demo tapes that way.....

Cheers,

David
 
dshoaf said:
If you've got Dolby-ized tapes, then there could be some problems with playback levels. Ideally, you'd be able to adjust the new ones to get sufficient levels so as not to upset the Dolby encoding but still something to think about.

I'm a dbx guy. ;) I did a bit of research before deciding which NR system to use, and dolby's critical reliance on playback levels made me shun it.
 
Orcinus said:
Neither machine does 3.75 IPS (the 3300SX is the 2-track model, which runs at 7.5 or 15 ips. Only the 4-track model ran at 3.75 and 7.5 ips).

I am not concerned about recording on the 3340, as I will do all the recording on the 3300SX.
Yes! I didn't see the '2T' logo.
 
I would first look for the Teac parts, if you can get new heads for that model, you would be far ahead of trying to cob something else on there.

I have a couple of sources for Teac parts also, if you want me to ask around about them.
 
cableguy2 said:
I would first look for the Teac parts, if you can get new heads for that model, you would be far ahead of trying to cob something else on there.

I have a couple of sources for Teac parts also, if you want me to ask around about them.


That would be great! I want a 2-track head from an A-3300SX 2T. (NOT the 4-head track!)

Oooh, better yet, I'll just take that Technics 1500 in your sig there! :D


:music:
 
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