Tascam M-1b - Connector Explanation

sr71rules

Member
I first learned about the M-1b via the manual I was reading (for fun, mind you) of the M-520. They mention the M-1b being a great way to easily increase the number of separate headphone mixes you can make. The M-1b is basically an 8 channel unbalanced line mixer but the 8 inputs are 1/2 normalled to 8 outputs. You can send audio into the top RCA jack (Left side of the image is the last jack, channel 8) and that audio goes both to the internal mixing circuit as well as the jack directly below. The great bit is the audio passing from the top jack to the bottom is unaffected by changes made to the controls on the mixer, namely volume and pan. The tiny mixer splits the audio allowing you to make a headphone mix on this mixer and then pass the audio through to a second or third M-1b, and then, if you wanted, onto another device. I'm sure going through all the jacks has some signal degradation by looking at the jacks inside the box they do not pass through any circuity at all.

Things I understand to be true:

Inputs 1-8 pass both to the mixer and to the outputs, labeled FLB, below them unchanged. I'm assuming FLB means foldback.

What I am looking to confirm:

'BUSS IN' is a stereo pair of inputs that is added to the main buss of the M-1b. The front panel has no controls for this at all. FLB below it works the same as the FLB jacks for the mono channels. You can pass a stereo pair basically though the unit in addition the 8 mono channels.

'LINE OUT' is the main buss of the unit and is volume controlled by the 'Master' volume knob on the front panel.

'AUX OUT' is a copy of 'LINE OUT'.

M-1b Connectors.jpg

The front of the device is pretty simple. 8 Volume knobs, 8 Pan knobs, a 'MASTER' knob with two overload LEDs, one for left, one for right. It then has two 1/4" jacks labeled 'Headphones' controlled by a single volume knob.

Does anyone have a manual for these? Why doesn't someone today replicate this functionality? Such an amazing utility in a studio or live situation. The more Tascam gear I learn about the more I appreciate what they did to change home recording. It's no wonder they have such a strong presence here in the 'Analog' section of this forum. Not the most 'high end' gear our there but the feature set for the price is excellent.

I've got two of these and counting...

Robert
 
What I am looking to confirm:
'BUSS IN' is a stereo pair of inputs that is added to the main buss of the M-1b. The front panel has no controls for this at all. FLB below it works the same as the FLB jacks for the mono channels. You can pass a stereo pair basically though the unit in addition the 8 mono channels.

'LINE OUT' is the main buss of the unit and is volume controlled by the 'Master' volume knob on the front panel.

'AUX OUT' is a copy of 'LINE OUT'.
Confirmed. The buss in level is controlled by what ever that source's controls have been set to. So you would adjust that from the source to balance it against whatever mix you created within the M-1B. The Master volume control on the M-1b will still effect the buss in level only it will not control it independently.

And the rest of it, you described accurately.

Cheers! :)
 
Wonderful! Thanks Ghost.

Do you know if Tascam every made a recommendation as to how many could be strung together in series?
 
Wonderful! Thanks Ghost.

Do you know if Tascam every made a recommendation as to how many could be strung together in series?

No. They would have never published hard info on something like that. But I guess you could look at the noise specs and quickly figure it out that the collective hiss and hum would grow, the more active circuits you had feeding a final destination. Look at mixer noise specs where they show you the s:n ratio for 1 mike to PGM out vs. 20 mics to PGM out. The noise adds up pretty quick!

So, like anything else in analog audio, only turn on the channels you're really needing and gain stage properly all along the way to keep the signal louder then the noise.

Cheers! :)
 
Pick me if you want Tascam info (manual) on this unit!!!

And recap the power supply if you want it very quiet!
 
The Tascam M-1B is my favorite line mixer. I have two of them. I use one as a sub for effects processor returns to my main mixer. I’m not using the other at the moment, but I can’t bear to part with it at the low prices they fetch on eBay and such. It’s too well made to give away. It’s a great mixer, but like nearly anything the specs can be improved somewhat with better op-amps and metal film resistors in the signal path. The stock op-amps are NJM2041DD, which is basically a lower noise version of the 4558. I like NE5532A for most things that come stock with a 4558 variant. The NJM4580 would also be a good choice, as it is a modern low-noise better performing amp in the same series as the 4558 type. Both the 5532 and 4580 will drop right in with no further mods needed to accommodate them.

Factory specs for the M-1B are as follows:

Freq response: 20Hz - 30Khz +/- 1dB
S/N ratio: 82 dB (IHF "A" WTD)
THD: 0.03% (1khz)
Crosstalk: 60 dB
2 rack spaces high

As for how many times you can daisy chain from foldback to foldback it depends, but in a studio with –10 dB line levels I wouldn’t want to go more than three and keep cable lengths as short as possible. The less physical breaks in the signal chain the better, as each one allows some degradation in quality and more likelihood for RF interference. It’s not much but I like to keep things simple. If your not actually pushing signals through them that will be recorded, but only for monitoring for the talent or something like that you can get away with more… as many as you like.

Here’s how I feel about the M-1B: If you have one or more be happy because you have a great sounding and versatile line mixer for many applications and it’s better built than newer units many times the price. If you don’t have one, buy one… you’ll find a use for it and be glad you did. ;)
 
looks like you're covered for the manual, but I've also got one I could scan - all of 8 pages with a nice 4-page centerfold schematic diagram.

I havn't done any full re-cap jobs, but I could imagine this wouldn't be too intimidating, maybe I'll give it a go sometime.

I think a few years ago there were several simple 'summing' style mixers that came out for a pretty penny when 'real time analog summing' of digital sources was hailed as the next necessary peice professional gear - (I'm sure they're still around, but I have a hard time imagining that they'd greatly outperform an M-1B.) I visited a freind with something like this that he seemed to like - IIRC it cost something like 2 or 3 grand. but thinking again about this, they likely don't even have the foldback, as they were'nt really intended to be multi-useful - thats why some of that Tascam 80's gear was so great, they were all like swiss-army audio devices that could be used 3-5 different ways....

I might try mine out as a summing mixer sometime though after I finally discover the perfect patchbay setup...:rolleyes:
 
I have two of them at the moment and I don't have any immediate plans to put them in the recording or mixing signal path (My M3500 has plenty of I/O at the moment) but having never modded anything this might make a fun place to start. Not too many things to work on and plenty of space to work on the circuit board. Having two would make it easy to A/B them before and after modding to see what change was (or wasn't...) made.

I am planning to use them as a way to increase the number of headphone mixes I can make but I was surprised when I first come across the mixer how similar it looks to a modern day 'Summing box' that people do seem to be going gaga over these days. Being -10 unbalanced would keep it out of most peoples racks though for that purpose. It's all about the mighty spec sheet these days.

I am continually blown away by the versatility of the gear Tascam made 'back in the day'.

Thanks for all the info!
 
Can it be used to connect hi fi equipment and switch between them, such as connecting several preamps and switching between them, as well as switching between several power amps at the mixer's outputs? (though with the power amps, you would still need to swap cables to the main speakers in order to listen, if not using headphones).
 
Can it be used to connect hi fi equipment and switch between them, such as connecting several preamps and switching between them, as well as switching between several power amps at the mixer's outputs? (though with the power amps, you would still need to swap cables to the main speakers in order to listen, if not using headphones).

You can connect any line level devices to it, yes including hi-fi such as tape decks, CD players, etc. But this is a line mixer so I wouldn't say switching, but rather mixing/blending. This is an 8-in stereo-out line mixer and a very versatile one. Well made, good specs, equally at home in the studio or a hi-fi rack. You've got 8-channels, each with level and pan control, plus a master level control and channel overload LEDs on the two main busses. Good product from Tascam's glory days.

A company came out with what was basically a clone of this mixer a few years ago for hundreds of dollars pitched at the digital crowd as an analog front end. The name of that company will come back to me any minute now. :D But the important thing is you can get a Tascam M-1B for around $50.00 maybe less. The last one I bought on eBay for $35.00 in excellent condition. In all fairness it should be going for more than that, but for now anyway it's a steal (Except for The Flower Pot Guy... 9guitar. He is dead to us... not an option. The only stealing going on there is him stealing from you) ;)
 
I've seen his auctions, always with the pots in the background. Along with outrageous prices. He has good feedback though.
 
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