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Problems with a 4 track cassette recorder
MUFF WIGGLER Forum Index -> General Gear  
Author Problems with a 4 track cassette recorder
hotstepper
Hey everybody,

I've been wanting to explore creating tape loops recently so I got myself a Yamaha mt50 4 track. Its my first 4 track so I could just not be doing this right, but when I was playing old cassettes to test the machine, the tape was being played at a much faster speed (it sounded like chipmunks) and tracks 3 and 4 seemed to also be playing backwards. Its a cool effect but I'd like it to just playback properly. Does anyone know how to fix this?
bobbylandry
This is all normal.

Most cassette 4 track machines run the tape faster to get a better quality recording. If you try to play back the Nirvana cassette someone bought at Sam Goody in 1992, or whatever, it will sound faster because the MT50 is running at a faster speed than your regular listening cassette player that the tape was meant for.

Tracks 3 and 4 also sound like they are playing backwards because they are reading the opposite side of the tape. That Nirvana tape from Sam Goody, or whatever, has half the album on one side and then you flip the tape over and the other half of the album is on the other side. So if you were to look at the tape, split along the path of the tape in 4, it would look like this:

Side A Left
Side A Right
thgiR B ediS
tfeL B ediS

I just tried way too hard to type that out and it doesn't even make sense. Haha. Your regular music cassette has a left and right stereo track going one direction, and then when you flip the tape over another left and right stereo track going the other direction, which is now forward since you flipped the tape. So when you put this tape in a 4 track recorder it can read these 4 tracks back at the same time and the 2 stereo tracks on side B that were backwards, so that when you flipped the tape over they played correctly, sound backwards when you're listening to them now in the same direction of side A.

If someone could explain this better than me that would be awesome since I'm not sure I'm making sense.
hotstepper
bobbylandry wrote:
This is all normal.

Most cassette 4 track machines run the tape faster to get a better quality recording. If you try to play back the Nirvana cassette someone bought at Sam Goody in 1992, or whatever, it will sound faster because the MT50 is running at a faster speed than your regular listening cassette player that the tape was meant for.

Tracks 3 and 4 also sound like they are playing backwards because they are reading the opposite side of the tape. That Nirvana tape from Sam Goody, or whatever, has half the album on one side and then you flip the tape over and the other half of the album is on the other side. So if you were to look at the tape, split along the path of the tape in 4, it would look like this:

Side A Left
Side A Right
thgiR B ediS
tfeL B ediS

I just tried way too hard to type that out and it doesn't even make sense. Haha. Your regular music cassette has a left and right stereo track going one direction, and then when you flip the tape over another left and right stereo track going the other direction, which is now forward since you flipped the tape. So when you put this tape in a 4 track recorder it can read these 4 tracks back at the same time and the 2 stereo tracks on side B that were backwards, so that when you flipped the tape over they played correctly, sound backwards when you're listening to them now in the same direction of side A.

If someone could explain this better than me that would be awesome since I'm not sure I'm making sense.


So since the old cassettes were recorded on something slower than the mt50 they play faster when I use this 4 track correct? and Im assuming this means that if I record whole new cassettes on the mt50 it will play back at the same speed?
bobbylandry
hotstepper wrote:
bobbylandry wrote:
This is all normal.

Most cassette 4 track machines run the tape faster to get a better quality recording. If you try to play back the Nirvana cassette someone bought at Sam Goody in 1992, or whatever, it will sound faster because the MT50 is running at a faster speed than your regular listening cassette player that the tape was meant for.

Tracks 3 and 4 also sound like they are playing backwards because they are reading the opposite side of the tape. That Nirvana tape from Sam Goody, or whatever, has half the album on one side and then you flip the tape over and the other half of the album is on the other side. So if you were to look at the tape, split along the path of the tape in 4, it would look like this:

Side A Left
Side A Right
thgiR B ediS
tfeL B ediS

I just tried way too hard to type that out and it doesn't even make sense. Haha. Your regular music cassette has a left and right stereo track going one direction, and then when you flip the tape over another left and right stereo track going the other direction, which is now forward since you flipped the tape. So when you put this tape in a 4 track recorder it can read these 4 tracks back at the same time and the 2 stereo tracks on side B that were backwards, so that when you flipped the tape over they played correctly, sound backwards when you're listening to them now in the same direction of side A.

If someone could explain this better than me that would be awesome since I'm not sure I'm making sense.


So since the old cassettes were recorded on something slower than the mt50 they play faster when I use this 4 track correct? and Im assuming this means that if I record whole new cassettes on the mt50 it will play back at the same speed?


Yea that's correct.

I think pre-recorded tapes and consumer tape decks like would be in an old car or a Walkman or a home stereo played back at 4.8 inches per second (IPS). I think most 4 track home recording type stuff plays back at 9.5 IPS. Then the big open real machines at the "real recording studios" that I first started with ran at either 15 IPS or 30 IPS. Someone is again welcome to correct that if I'm wrong.
JimY
Tape speeds go down in halves from 30IPS.
Audio cassette normal speed is a low 1 7/8IPS. Portastudio and twin deck high-speed dubbing is twice that.

Many of the last cassette decks made had electronic speed control, so there could be a hack to drop the speed down to normal.
electricfence
For the OP, and forgive me if this is all to obvious, this all means that whatever cassette you record on your Yamaha machine ought to sound right (as far as speed goes) only when played on the Yamaha. If you want to then make a cassette that you can play on a walkman or other standard tape deck, you'll need to mix it down using another tape recorder. (You could also mix it down into your DAW.)
IR
Most 4 tracks work at normal speed. Some have a switch to let you play and record faster for better quality. A few only work at a faster speed.
bobbylandry
JimY wrote:
Tape speeds go down in halves from 30IPS.
Audio cassette normal speed is a low 1 7/8IPS. Portastudio and twin deck high-speed dubbing is twice that.

Many of the last cassette decks made had electronic speed control, so there could be a hack to drop the speed down to normal.


Yea this is totally correct, I've been using a Yamaha MT4X and they have the tape speed written in centimeters in the front, which is where I came up with 4.8 and 9.5. The MT50 only runs at 9.5 cm/sec I think.

The answer to OP's question is also the beginning of chapter 1 in the MT50 manual, with nice pictures and everything.

MT50 Manual
hotstepper
bobbylandry wrote:
JimY wrote:
Tape speeds go down in halves from 30IPS.
Audio cassette normal speed is a low 1 7/8IPS. Portastudio and twin deck high-speed dubbing is twice that.

Many of the last cassette decks made had electronic speed control, so there could be a hack to drop the speed down to normal.


Yea this is totally correct, I've been using a Yamaha MT4X and they have the tape speed written in centimeters in the front, which is where I came up with 4.8 and 9.5. The MT50 only runs at 9.5 cm/sec I think.

The answer to OP's question is also the beginning of chapter 1 in the MT50 manual, with nice pictures and everything.

MT50 Manual


Thanks a lot for your help! I got everything working. Right now though id like to try disabling my erase head so that I can do live sound on sound looping. I've tried covering it up with tape and tin foil but it doesnt really work. Do you have any advice on how to disable the head? I'd also be willing to add a switch to turn off the head if its easy (I dont know a thing about electronics, but I do know how to solder)
Blairio
I used to own Tascam 244 and 246 portastudios. These ran at double speed, and when used with 'metal' (as opposed to 'chrome' or 'ferrous') cassettes, the sound quality was very good. The trouble was that using metal cassettes wore out the record and play tape heads much faster.

I know this is off-topic, but there are some pretty cheap & decent looper pedals out there, which might save you having to modify your MT50.

For instance, the "Landlord FX Happy Looper" pedal, which is around 49 GBP here in the UK.
hotstepper
So I opened up the 4 track and I managed to just unscrew the erase head so it doesn't get pushed up to the tape and that seems to work. However, I really underestimated how enraging it can be to splice my own 30 second loop tape and will be getting a premade one tomorrow. I can say for sure that everything else still works as its supposed to.
electricfence
hotstepper wrote:
Right now though id like to try disabling my erase head so that I can do live sound on sound looping. I've tried covering it up with tape and tin foil but it doesnt really work. Do you have any advice on how to disable the head?


I think I've seen Hainbach put a guitar pick between the erase head and the tape. I'm not sure how that would work on your four-track machine, since I suppose it must be able to erase both sides of the tape at once.
JimY
Depends on the erase head wiring. How many wires to it?
I can't find an MT50 service schematic online. I found one fpr the MT120 and that has a fully independent 4 track erase which means 8 wires to the erase head, although as 4 of those are the same power supply ground, you might have 4 wires and a cable screen for the ground.
Since the erase signal is also used in the recording head, it might be best just to switch off the wires to the erase head that aren't ground.
smetak
electricfence wrote:
hotstepper wrote:
Right now though id like to try disabling my erase head so that I can do live sound on sound looping. I've tried covering it up with tape and tin foil but it doesnt really work. Do you have any advice on how to disable the head?


I think I've seen Hainbach put a guitar pick between the erase head and the tape. I'm not sure how that would work on your four-track machine, since I suppose it must be able to erase both sides of the tape at once.


Yep, here it is:



He's using a cheap Fostex x12 for the demo. There's also another very fine Hainbach demo for tape delays with similar technique - where he's using an old, but very useful, three-head Marantz field recorder.

I would deem the Hainbach demos mandatory for what you are attempting. The man is a genius.
JimY
I had completely forgotten that Endless tapes were a commercially available thing.
Just found this...
https://tapeline.info/v2/endless-loop-tapes.html
smetak
JimY wrote:
I had completely forgotten that Endless tapes were a commercially available thing.
Just found this...
https://tapeline.info/v2/endless-loop-tapes.html


These guys are great! Bought a few custom-made tapes from them.
hotstepper
smetak wrote:
electricfence wrote:
hotstepper wrote:
Right now though id like to try disabling my erase head so that I can do live sound on sound looping. I've tried covering it up with tape and tin foil but it doesnt really work. Do you have any advice on how to disable the head?


I think I've seen Hainbach put a guitar pick between the erase head and the tape. I'm not sure how that would work on your four-track machine, since I suppose it must be able to erase both sides of the tape at once.


Yep, here it is:



He's using a cheap Fostex x12 for the demo. There's also another very fine Hainbach demo for tape delays with similar technique - where he's using an old, but very useful, three-head Marantz field recorder.

I would deem the Hainbach demos mandatory for what you are attempting. The man is a genius.


His video is actually where I go the idea from! I managed to find my 4 track quite cheaply right after watching it so I bought it for this purpose. I dont think unscrewing the head so it doesnt touch the tape worked because the loop I made keeps restarting and cant overdub. Im thinking of taking it to an audio shop I know to see if they can mod this out.
smetak
Are you sure that a regular tape or tin foil doesn't work? Unscrewing the head seems to be a bit of a hassle - I followed Hainbach's advice, which works pitch-perfect (but, again, I have similar gear).

Incidentally, for tapes and cassettes, here's another fine channel:

https://www.youtube.com/user/amuletsmusic
hotstepper
smetak wrote:
Are you sure that a regular tape or tin foil doesn't work? Unscrewing the head seems to be a bit of a hassle - I followed Hainbach's advice, which works pitch-perfect (but, again, I have similar gear).

Incidentally, for tapes and cassettes, here's another fine channel:

https://www.youtube.com/user/amuletsmusic


Yeah the tape or tin foil method didnt really work out for me im not sure why. The erase head isnt touching the tape and I also have tape covering the hole it comes out from just in case but I still cant do overdubs.
JimY
Erase head disconnection - mechanical or electrical, isn't quite the end of erasing. Most audio tapes use high-frequency (inaudible) AC erase which is the same as used in the record heads as the bias. Both erase and bias have the purpose of upsetting the magnetic tape particles to make it easier to magnetise by audio frequencies. The erase head has a stronger AC applied without the audio so leaves no trace of any audio; while the recording head should add fresh audio by superimposing it on the bias signal
I suspect a high bias tape might retain old audio from an overdub better than ordinary ferric.

Play with any tape type switching the machine has and try overdubbing with lower record signal level, in the hope of not obliterating the existing audio.
pricklyrobot
smetak wrote:
JimY wrote:
I had completely forgotten that Endless tapes were a commercially available thing.
Just found this...
https://tapeline.info/v2/endless-loop-tapes.html


These guys are great! Bought a few custom-made tapes from them.


Anyone know a good US source for ready-made loop cassettes in varying lengths?
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