Tascam mixing desks

[Uli_the_Grasso]

Hello Tascam users,

your precious Tascam mixer might sound nice, but also completely break when just an output is severely over-loaded.

I serviced a Tascam 24ch inline console which must have been from around ´98. Someone had connected the output of a 100W loudspeaker amplifier to a line output of the Tascam. An op-amp chip was literally blown, shortcutting the power supply, rendering the desk useless. This could happen only because Tascam was too scroogy to equip the outputs with current-limiting series resistors. Just 100 Ohms would have given the shutdown circuits within the op-amp chip a fair chance and would have prevented the welding of the power supply, i.e. only one output channel would have blown instead of the whole desk. Also for reasons of self-oscillation and RF behavior, i.e. sound quality and defects when bad luck strikes, it is not good practice to wire the silicium directly to the jacks.

And REAL mixing desks have output transformers. Servo-balancing is o.k. for inputs (except for particularily hard environments as big live concerts), but it is a PITA for outputs (being instable and causing ground loops).

This desk was a nightmare to service, nearly impossible to open that bloody thing. That took two hours. And then we had to rest that huge thing (two feet high and four feet long) in disassembled state on its rear panel like the tower of Pisa wanting to fall to one side or the Golden Gate bridge shaking in the wind; crap on a junkyard.

Just remember: Semi-pro is not pro.

[The Ghost of FM]

Hopefully, us semi-pro, home recording enthusiasts here won't be as silly as your client was in plugging a 100 watt amp direct into his mixer!

Cheers!

[Uli_the_Grasso]

Silly? Go into a musical instruments shop and see what loudspeaker cables look like! Often they are round and look like line and microphone cables. Often they have 1/4 inch jacks because many loudspeaker cabinets have this type of plugs.

And what happens if you connect two line outs and load them with reasonable level for some time? Will one break? A 100W/4Ohms amplifier can output 20Veff, while a Tascam line output can output 10Veff. Line outs of pro equipment and headphone amplifiers are not so daisy either.

Failures happen and sum. Failing equipment ends in a mess.

[The Ghost of FM]

Well then, it is fortunate that you have chosen to be an electronics technician as manufacturers seem determined to keep you employed with less then perfection in their designs.

Cheers!

[Uli_the_Grasso]

I earned experience and nothing else because this client, a "semi-pro, home recording enthusiast" he may have been, turned out to be a poor idiot.

How is your 16-track doing?

[The Ghost of FM]

How is your 16-track doing?

Thanks to your help and advice via e-mail, I will take a stab at opening up the back of the amplifier unit to see if I can inspect the main board for cold solder joints and also clean the relays while I am in there though, if they are a function of protection during power up/down cycling, I don't think they are the problem.

Cold solder joints are where my head is at right now.

Do you agree?

Thanks again.

Cheers!

[Track Rat]

No problems with my M-3500 so far. So it's a bad idea to plug the outputs of a power amp into a line input, eh?

[kiira]

Originally Posted by Track Rat

No problems with my M-3500 so far. So it's a bad idea to plug the outputs of a power amp into a line input, eh?

Yeah but what I wanna know is if it is also bad to plug the outputs of the board back into the same power amp? I need a comprehensive list of EVERY incredibley dumb thing I can do please?

[kiira]

Originally Posted by Uli_the_Grasso

Hello Tascam users,

your precious Tascam mixer might sound nice, but also completely break when just an output is severely over-loaded.

YOU"RE SO MEAN!!!


TASCAM LOVE SOLIDARITY!!!!

[The Ghost of FM]

Originally Posted by kiira

YOU"RE SO MEAN!!!


TASCAM LOVE SOLIDARITY!!!!

Uli is NOT mean.

He is Dutch and has a bit of language barrier with us nice polite north Americans, is all.

Cheers!

[A Reel Person]

He just needed more MACHO input transistors!!

... (or a frickin' clue!)

[Uli_the_Grasso]

Ghost of FM wrote:
>Cold solder joints are where my head is at right now.
>Do you agree?

In conjunction with failing FETs and possibly relais. Cold solder joints do not happen out of the blue but come from mechanical and thermical stress.

I am not Dutch, I am German. You know, Germans are rude. Nearly as rude as US military and intelligence personnel: http://www.fromthewilderness.com/fre...children.shtml

Reel-to-Reel and Track Rat did not read my post well: No input transistor was involved but a line output, actually Aux Out 4. A power amp output ran into a line output. Do you get that?

If you are careful not to put out too high a voltage, you can connect a power amp to a line input, because an input is passive. But an output with low source resistance tries to shortcut the alien voltage appearing at its output terminal, so it heats up and breaks. Even 100mV can be enough to cause a current high enough to destroy the amp. This is why I cannot predict what happens when you connect two outputs. I expressed that by writing "Will one fail?", which seems to be clear language, but it also seems that you understand only what you want to understand.

[Son of Mixerman]

Originally Posted by Uli_the_Grasso

Just remember: Semi-pro is not pro.

Its not just Tascam my German friend. Neve, SSL, Otari's etc all suffer to some extent from decisions made by bean counters DO a search on Geoff Tanner, Ex Neve fella. Tascam did have some large format consoles that are pretty decent desks, but not typically within the affordability requirements of home users. M600, M700 and the M5000 aka Baby SSL. If you ask me, more techs need to be involved in desk design. Engineers(guilty) sometimes down think about things that a tech might encounter everyday.

Recording rule of thumb: Undestand electron flow prior to plugging in anything.

Recording Rule of thumb: Read the manual before plugging in the power.

Recording Rule of thumb: Electronic stuff always breaks because the universal balancing constant.

Opamps, can't record with them can't record without them

Hey.... I smell smoke?


SoMm

[A Reel Person]

I've now gone back & read the worthless post of what a bitch you had about Tascams not being "REAL" consoles. You have a better concept. You are a genius. I get it.

If you're stupid enough to plug a hot speaker lead into an AUX OUT, you get what you pay for. That, and your stupid bitch of an attitude.

[Herm]

Key words in his post. severely over-loaded

Purpose of that?

I have no frickin idea

I also have a question for you Reel

Will a tascam 22-4 work with a dx-4d ? I know they had a dedicated dbx unit for that machine but I was wondering if the dx-4d would work with it.

[Herm]

Uli posted, I am not Dutch, I am German. You know, Germans are rude. Nearly as rude as US military and intelligence personnel:

I was going to let this go but I changed my mind.

First Uli this is a Recording forum and if you want to trash equipment and its design I dont give a shit one way or another.
But you can take you political shit and US bashing and stick it up your ass!

If you want to talk about torturing lets look back a few years and see whom the exsperts where at that.

[A Reel Person]

The 22-4 is the one with the full DX-4D compatibility.

[Herm]

Thank you Reel

[MadAudio]

My dad used to press and sell his own apple cider. The slogan: "If it's Dutch, it ain't much. But if it's German, beware of vermin."

[The Ghost of FM]

I'll bet your mom says your dad was a cunning linguist.

Cheers!

[Uli_the_Grasso]

After twenty-five years of building mixers they still produce such a crap. A big mixing desk which cannot be opened for service? I guess that is a perfect fit for Reel_to_Reel and other madmen.

[boingoman]

Originally Posted by Uli_the_Grasso

After twenty-five years of building mixers they still produce such a crap. A big mixing desk which cannot be opened for service? I guess that is a perfect fit for Reel_to_Reel and other madmen.

You could always not work on them, saving yourself some aggravation......

[MadAudio]

Originally Posted by The Ghost of FM

I'll bet your mom says your dad was a cunning linguist.

Normally I love that phrase. But the mere thought, even the slightest suggestion, of my parents having sex is enough to make me nauseous. And they're not even ugly!

[Uli_the_Grasso]

Boingoman, I have not any personal problem. All I wanted to tell you folks is that a Tascam mixing desk, while looking proper and powerful, does not necessarily behave so. I have already told you about failing transistors, relays and DC motors in Teac/Tascam tape machines. I could tell you even more horror stories, also about Behringer, Fostex, Studer, Fender, .... At least half of what I repair failed due to production or design fault. Anyone who is in for analogue equipment can use the information provided by me to his advantage.

[The Ghost of FM]

Originally Posted by Uli_the_Grasso

Boingoman, I have not any personal problem. All I wanted to tell you folks is that a Tascam mixing desk, while looking proper and powerful, does not necessarily behave so. I have already told you about failing transistors, relays and DC motors in Teac/Tascam tape machines. I could tell you even more horror stories, also about Behringer, Fostex, Studer, Fender, .... At least half of what I repair failed due to production or design fault. Anyone who is in for analogue equipment can use the information provided by me to his advantage.

All excellent points, Uli.

By the way, Uli, we have a section on here called the Drangon's Cave where off topic discussion is encouraged and talk of equipment and the recording process is discouraged. I think we would truly enjoy your participation there and would yourself.

Cheers!