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Amp Internals 2

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JR.junior View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JR.junior Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2013 at 11:13am
Try reach him via PM box!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Biggus Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2013 at 11:23am
He won't be able to PM as less than 10 points.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WILL* Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 12:02am
the t.amp TA2400, what did you think about it?



he have 2kW RMS in brigde mode?Big smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AudioSystemsEngineer Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 12:17am
These are an (almost exact) copy of the QSC RMX2400 series.
also appear branded 'c-mark' and 'audiohead'.
they are a dual rail Class-G design (a high-speed FET switches the supply rails from ~50V up to ~80V as the input waveform passes  a pre-set point).
This results in lower power dissipation in the output stages (so they can get away with fewer devices).
They use a crow-bar to limit the output current - which is pretty crude.
personally, i wouldn't run these into less that 4 Ohms / channel (8 Ohms Bridged) and make sure the clip lights just blink in load sections. (the clip leds sense the error voltage - so they are a pretty good indicator of distortion / when the amp is struggling). 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 12:21am
When considering this amp do remember it was for a time about the cheapest amp you could buy, watt for watt.
Yours appears to have Nippon Chemicon capacitors? Never seen those before in one of these, they normally use cheap chinese grenades.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AudioSystemsEngineer Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 12:46am
i hated working on the audiohead 4000 - they didn't follow QSC's design of 3 rails...opting for a nice explody 2 rail solution.
also, the +/- 15V rails for the input signal part are derrived by using 15V zeners + big red-hot resistors.
this means you can't run it up on a variac because there isn't enough voltage for the op amps.
2 ways round this...
1. disconnect the resistors and use a seperate 15V psu, or.
2. bypass the resistors with a lower value (but remember to take the bypass off later !! )
I should also mention, if the amp has been run at continuous clipping... the clip LED's or their series resistor will die.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 2:21pm
Originally posted by AudioSystemsEngineer AudioSystemsEngineer wrote:


I should also mention, if the amp has been run at continuous clipping... the clip LED's or their series resistor will die.


LOL! That piece of design genius deserves a prize....
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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JR.junior View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JR.junior Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 4:00pm
LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 4:23pm
"also, the +/- 15V rails for the input signal part are derrived by using 15V zeners + big red-hot resistors"

Built in obsolescence. I´ve even seen that one in a couple of Crown amps, who you´d think would know better.

Ouch 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tan-2 Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 6:53pm
The simple Zener reg circuit is straight forwards in most circuits and can be up graded with reg's. if them drop feed resistors are to hot then up there wattage or blot them to the chassis has it will aid cooling them down.

Clipping at high levels.. That will sound bad...
Logic will get you from A to B. Imagination will take you everywhere.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bitSmasher Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 9:36pm
Originally posted by studio45 studio45 wrote:

Originally posted by AudioSystemsEngineer AudioSystemsEngineer wrote:


I should also mention, if the amp has been run at continuous clipping... the clip LED's or their series resistor will die.
LOL! That piece of design genius deserves a prize....
audiophiles would call it "burning in"

"I ran my amp flat out with sine waves until it stopped clipping, now it's burnt in it sounds better"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 14 November 2013 at 11:01pm
nothing wrong with zeners off the dc bus, good enough for Cloud, HH, Carlsbro, QSC, Wharfedale, Behringer, Mackie etc
Kevin

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