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Dirt Cheap Stax Amp DIY - new schematic updated! - Page 7

post #91 of 99

while according to the Tube Cad articles the name SRPP is a recent invention - with ambiguous interpertations - I don't think it can be stretched to cover the present circuit

 

you have "feedforward" push-pull - the bias/pull down current is modulated by the amplified signal V, scaled by a R and current mirror

 

there is no connection to the load current demand - it could be helpful if it "lined up" with the load demand - but with ES headphones being a fair capacitor it doesn't happen here


Edited by jcx - 4/13/13 at 9:40am
post #92 of 99
Thread Starter 
Quote:
Originally Posted by jcx View Post

while according to the Tube Cad articles the name SRPP is a recent invention - with ambiguous interpertations - I don't think it can be stretched to cover the present circuit

 

you have "feedforward" push-pull - the bias/pull down current is modulated by the amplified signal V, scaled by a R and current mirror

 

there is no connection to the load current demand - it could be helpful if it "lined up" with the load demand - but with ES headphones being a fair capacitor it doesn't happen here

I agree, while I was testing the output wave form, I found out even though this circuit has overall flatter FR, but I also tried loading the upper two transistors with resistors or CCS load. and resistor load clips very clean and smooth, sounds like a triode, CCS is a little harsh when clipping, while this SRPP thing clips very harsh. I will try to play with higher idle current once I received the heat sinks I ordered a while ago. 

 

I think a CCS loaded emitter follower can do what you were describing here. emitter follower makes sure the voltage is right and CCS is making sure the current is there when demanded by the C load, especially when output voltage is at max, when current is 0 or when voltage is at 0 and output current is at max. 


Edited by wdiabc - 4/13/13 at 10:01am
post #93 of 99
Sorry if this is gravedigging...
I'm probably going to end up building my own stax amp and don't even know where to start xD
If someone could help me, that'd be awesome
post #94 of 99

Go to the other site.........

post #95 of 99
Just start with the T2. Live hard or die trying.
post #96 of 99

Yeah, there site would be good and also what you'd want to build (tube, SS etc.).  Since I just posted it in the Stax thread, this is quite cheap:

 

 

Not really done for high performance and more for being odd.  smily_headphones1.gif

post #97 of 99

Sorry, stupid impulse post. When i stopped and think abut it i realized it is a dangerous, stupid idea.

 

Hi

 

I needd a Stax amp quick for testing purposes and this seems to fit the bill pefectly! Just one question, I live in Sweden we have 230v. Thats about 330v retified. Some cleaning and a simple regulator could take it down to 300. Same goes for the bias supply. Do i need a transformer at all?

 

Best Regards Christian


Edited by ervstil - 5/27/14 at 9:02am
post #98 of 99

For safety sake, yes you need a transformer. 

post #99 of 99
This is quite interesting.. Suitable for a first 'real' project?
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