Current Dumping Amp

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#3
the link doesn't work any longer

Hello,

a friend's 606 just has shown white smoke. Therefore I need the schematics. Pityfully the link for the PDF document doesn't work any longer.

Can anybody help me ?

kind regards, and many thanks in advance,
Hartmut
 
#5
Re: Re: the link doesn't work any longer

tl said:

Try a google search for '606schematic.pdf'. You will find this discussion and two versions of the schematics.
Click to expand...

Thomas,

thanks alot, I then found it there:

http://home.jps.net/~shiloh/606schematic.pdf

there is another version, but nearly nonreadable:

http://www.vintagebroadcasting.org.uk/htdocs/manualpdf/606schematic.pdf

Initially, I found only manuls with hotbot and "606 Quad". Then I found this thread with DIYaudio's search function.

kind regards,
Hartmut
 
#7
I don't think the 606 is still a current dumping amp. For sure, the 405 was. The original. Current dumping is a specific concept with a class A amp driving both the load and a class B amp. When the class B amp kicks in, a very clever circuit takes care of the additional gain from that, and keeps the loop gain constant. This avoids the take-over distortion you find for instance in the Elektor amp superficially like it.
The same components taking care of that also take care of the freq compensation. Therefore, a real current dumping amp shows a compound feedback with an L and a C.

Edit: Yes, the 606 is a CD amp. Look at the feedback bridge.

Jan Didden
 
#9
Hi all,
Jan,
quad 606 is perfectly "current dumping" and to show the enough it verify the balancing of the output bridge ( C(47p) L4 ) = ((R29+R30) R24). The class A amp to be fully grown by the group of transistor to the left of the D4 etc. while the class B is the BJTs battery ( 3+3 ) to DX. There is any theoretical difference among 405 and 606!

Piergiorgio,
the circuit that you have pointed out is not a " current dumping " but an analogous variation to my circuit ( voltage NFB / transimpedance output )

ciao

Mauro
 
#10
Hi Mauro, it's a pleasure to see You back.
The reported project is said to be a current dumping one by the author of the Elektor contribution, GSchmidt.

In the net many variation of a opamp driving a class B stage with feedforward feedback is currently called current dumping.

In fact the IV transconductance power stage, common also to many discrete design, seems to be the best sounding topology. I'm coming into this project searching some information about design You pointed out in this forum.

The article referred should be found somewher in usenet, but I was not able to find it, see:

http://forum.allaboutcircuits.com/newsgroups/viewtopic.php?t=26341&start=45
 
#11
plovati said:
The simpler and cheaper current Dumping amplifier I known:

http://www.armory.com/~rstevew/Public/Ccts/4oma120w.gif

Is a 120W published on Electronics, about the late 70's. I have a better copy at home, I'll tried to scan and post it.

I always wondering myself if this project may works, seems too simple to be true.
Click to expand...


This is not a current dumping amp as defined by the QUAD 405. This is a question of definition. The Elektor "dumps" current into the load, but so does any amp. The term current dumping was originally coined by QUAD to describe the specific feedback arrangement that keeps loop gain constant independent of feedback. In the Elektor, loop gain varies all over the place during a signal cycle.
But, since "current dumping" is basically a commercial term, just like "stasis" or "holographic preamp", you are free to use it and confuse us all 😉

Jan Didden
 
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