Inspired to modify my Tascam

[PRR]

> Here's the schematics:

80%-90% same as mine. And (even though I have not used it in a while) I like mine.

Big difference around the EQ. You have coils and (I forgot) I have simulated (chip) inductances. So you have a 2-frequency switch, I have variable center freq. That would be worth changing, except it needs a very odd 2-knob 3-ganged pot: a 100K on upper knob, and dual 100K tapered pots on the bottom knob. You could just slip one of those small P-sonic dual-pots next to the boost/cut knob, but it would be ugly.

There may be some small differences in gain structure. I'll check at work.

Yeah, I could see changing out 4558s. TASCAM did (IMHO) a brilliant job of designing the system around the available parts (which is why it all runs at -10dBu) but still: 4558 is so 1973 new-fi.

> Hey, I didn't know it used input transformers.

Wasn't any "serious" alternative in 1974. You could get low noise at 1K impedance, but not at 150Ω sources, or not reliably in production. Even with discrete: look at all the classic op-amp modules, they all were made for transformer-in.

Even the early Bi-Amp boards (circa 1979?) used transformers. Those guys would have dearly loved to go transformerless to save cost and especially WEIGHT: a big hunk of iron on a PCB in the back of a van is begging to crack a board. The first "low Z" transformerless mike amp I used totally sucked, noise you could not ignore. It took a while for transformers to fade away.

> Are they any good?

They are not junk, but I can't say I've seriously flogged them. I suspect loud sources on big condensers WILL need padding. However the first step on the built-in pad is -20dB, a rather large step.

If you don't like them, replace them. About 1:4 ratio, not very fussy. Of course replacing all eight transformers with "something good" will cost more than the entire board "is worth".

And you will never find a board easier to work in. Many "great" boards open-up just as easy (3 screws to pull one strip, 14 screws to pull 8 inputs and 4 submaster strips) but they tend to be cluttered with parts, the Model 5 boards have only a few parts.

 

[Flatpicker]

Cool. Now I have to save my money for yet another project. :roll: :green:

 

[PRR]

> Here's the schematics: Line Module: http://rattletree.com/DIYpics/linemodule.gif

Same building blocks, but a 201C puts them together a little different.

TASCAM Model 5 201C channel strip

Actually a very different EQ scheme. Insert and fader have swapped positions. One obvious advantage is that with 201C layout, a faded-down channel won't leak EQ hiss into the bus. Also the 201C mike amp has about 6dB more maximum gain, while your 201 takes a little more gain in the EQ driver than the 201C takes in the pan-assign driver. Subtle changes, meaning TASCAM was tweaking. (Though moving Send/RCV from post-All to pre-All is a radical operational change... I don't have a full manual here but there may have been a documented hack to make my model's topology more like yours.)

The submaster module (which completes the main signal path) is identical to yours, from Buss In to main Line Out and also the Effects RCV path to the main summer. (trimmer R101 is 220K on my sheet, but the nominal levels are the same: 8dB of gain. So the actual value of R101 should be 50K. Maybe they ran out of odd-value 150K pots and switched to standard 220K?)

Aside from the obvious 5532: consider LM833. I suspect a LM833 "IS" a 5532, except different enough to avoid copyright infringement. At least it will foil people who think they hate 5532.

While the typical bias current on these audio chips is 10 times higher than on 741/4558-class devices, the maximum bias currents are not very different (unless you paid for a premium 741A). So if TASCAM did their job (and wasn't hand-selecting low-bias chips), the average 5532/LM833 will switch-pop worse than the average 4558, but not much worse than a worst-case 4558, and not bad enough to be unusable.

 

[manulaudic]

Hi all, i've been looking for info on this board. Looking for the schematics of the whole consoles so i can start upgrading the caps and what not...
All the links are down so hopefully someone has them still on their machine?

Much appreciated-
Manu

 

[Khron]

Might this help?

https://elektrotanya.com/teac_tascam_model_5_5a_series_mixer_sm.pdf/download.html

 

[manulaudic]

Might this help?

https://elektrotanya.com/teac_tascam_model_5_5a_series_mixer_sm.pdf/download.html

I don't know how similar the model 5 is to the model 3 but the tascam M30 is the teac model 3.

I'll look into it.
Thanks

 

[Khron]

To be fair, you didn't specify any particular model, and the photo in the first post of this thread is of a Model 5, so... ;D

But some Model 3 info should be here:
https://elektrotanya.com/teac_tascam_model_3_series_mixer_sm.pdf/download.html

 

[manulaudic]

To be fair, you didn't specify any particular model, and the photo in the first post of this thread is of a Model 5, so... ;D

But some Model 3 info should be here:
https://elektrotanya.com/teac_tascam_model_3_series_mixer_sm.pdf/download.html

Oh my you are right haha. I have searched so much on that day with "tascam m-30" that I thought I ended on a thread on they model.

My apologies and thanks for your help !

 

[Khron]

No worries, no harm done ;D Just another case of "be careful what you wish for"... In some ways