[tyre]

Quote:

I have my sources but I can't post anything about them.  Same deal as I knew about the takeover a long time ago but couldn't say anything. 
 

 
You seem to be relatively unfazed by this acquisition. Mr. Gilmore as well. Perhaps there's more to this news than meets the eye. In your opinion, would it be wise to buy whatever Stax equipment we want as soon as possible, or wait it out and hope for the best?

 

[Currawong]

Said Chinese company has a lot of foreigners in their team that look interesting and possibly serious.  Still, many questions, few answers.

 

[spritzer]

I'm not too worried about all of this, I was certainly more worried about the future without Stax getting some much needed capital. I'm also sure Edifer know why Stax are one of the most respected brands in the world, they make solid products that last for a very long time.  Being Made in Japan is a large part of that but that some of the sub assemblies can be made in China at a lower cost and to the same spec as the current stuff.  I also hope that this will open Stax up a bit to non-Japanese tech since they are a too focused in Japanese transistors for instance.  They are still whittling away at their stock of 2SA1968's when IXYS makes some excellent replacement. 

 

[alcofribas]

Are there common uses for high voltage bipolar transistors other than CRTs ?  In other words is this a technology that's likely to disappear, as is happening with so much analog now?  But you probably can design good estat amps using high-voltage MOSFETs.

 

[kevin gilmore]

These days there is absolutely no use for those very low capacitance, high voltage transistors.
Which is why they are being discontinued.  The mosfets that do over 1kv have huge gate capacitances
that are going to require much more drive power to accomplish the same thing. Some newer parts
are showing up at small boutique silicon manufacturers. Generally this also means the price
of the individual parts is going to go up significantly. Overall, the price of the amplifiers will not
go up much.
 
i'm expecting new technologies from ixys and a couple of other manufacturers to show up
within the next year, long before stocks of the old parts go away.

 

[schorsch]

New universal headphone amp!
 
Found an interesting amp made by a German highend audio maker (tubes...)
 
malvalve headamp 3
 
It is stated that it can drive all kinds of earspeakers like electrostatic (Stax) / magnetostaic / dynamic ....
 
Hope to get more information soon )
 
 
Regards Georg
 
 

 

[spritzer]

As a 2*12W amp it probably uses transformers to power the Stax outputs.  Nothing new there and the quality of said iron is crucial. 

 

[Pirx]

Hello
 
I have bought brand new SR-507 and used SRM-727A. Amplifier was modified by previous owner.
But I have measured DC offset: 2,5 V in left channel and 6,5 V in right.
How can I set right DC offset and check if the bias is right?
This thread is very long but I didn't find info how to rebias this amp.
Only Spritzer said it should be done after mod.
 

 

[livewire]

You should ask spritzer, he's the expert.
I'm sure he would love to give you a detailed explanation on how to do it.

 

[spritzer]

With a 717/727 the offset and balance are within spec or you don't have any sound since the servo shuts off the output if it gets out of line.  If you'd like to measure it then it's the same as with all the other DC-coupled Stax amps, measure between + and - for each channel and adjust the balance pot for 0VDC.  Measure between + and ground to adjust the offset.  Measurements are taken at the Stax sockets on the front panel. 

 

[Pirx]

Thank you for your answer Spritzer
Quote:

Originally Posted by spritzer /img/forum/go_quote.gif
 
With a 717/727 the offset and balance are within spec or you don't have any sound since the servo shuts off the output if it gets out of line.

Great news !!! Do you exactly know how much is "out of line"?
 
 
Quote:

If you'd like to measure it then it's the same as with all the other DC-coupled Stax amps, measure between + and - for each channel and adjust the balance pot for 0VDC.

 
I did measure between + and - for each channel and got 2,5 and 6,5 V.
 
 
Quote:

Measure between + and ground to adjust the offset.

 
The question is how to adjust? I have found two variable resistors but I have no idea if I should touch any of them
 
Did modyfication change transistors bias in power stage?
 
 

 

[schorsch]

Malvalve update,
 
I wrote an Email where I could listen to the amp and if there will be a Stax only amp!
Their answer was
 
That they are goin a so called: "power amp one OTL-Stax"
 
Which sounds pretty interesting
 
Regards Georg

 

[Hawaiiancerveza]

wow Stax need a lot of power eh?

 

[livewire]

Not really. What is needed is "high voltage".
Voltage is part of the power equation.

 

[Hawaiiancerveza]

Can Stax ear speakers be run from another amp other than an electrostatic amp?