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Old 26th October 2010, 11:07 PM   #191
Zen Mod is offline Zen Mod  Serbia
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me not likee twice shorter pedals , even when I have twice stronger legs

what's amount of 801's impedance modulus nastiness ?
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Old 27th October 2010, 06:50 PM   #192
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The amount of 801's impedance modulus nastiness.
The sales brochure from the early eighties states that the impedance characteristics (8ohm) over the entire frequency spectrum is nearly flat ..? So for what it's worth..

Concerning the a75 I don´t know this amp. But can see there is clearly an increasing virtuosity in every new amp composition that is released.

The amp must outperform my beard p100. So better dynamics and better mids. And both are already good.

I need to be able to hear which brand and type of strings are used on an acoustic guitar. I need to be able to hear who is the builder of an instrument. a live performance must sound like a live performance. I need to hear the breathing of a musician whilst playing . I need to be able to hear with full dynamics someone accidently hitting a microphonestand during a full cresendo. etc my current set/up has these qualities which i don´t t hear to often in other set/ups

But please help me I have been playing a bit with the Aleph-x calculationsheet on this forum.
If i'm correctly using the sheet it tells me 20 v at the output fets
7amp bias
60% cs
wil give me
81 watts into 8 ohm
145 watts into 4 ohm (lower than 4 ohm things don´t look nice)..
with a total heathsink kw of 0,21 temp will be 80 degrees (little hot maybe)

I think this won´t be a to bad amp or do i make a mistake (admitted I don´t know the specs of the heathsinks)

regarding the chef the gaar amp. would it be possible to put different more powerfull single ended clas a output stage behind...

By the way the wadia cd player gives 50db of output could that be of help in choosing amp

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Old 27th October 2010, 07:27 PM   #193
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by Alettagla View Post
.........

regarding the chef the gaar amp. would it be possible to put different more powerfull single ended clas a output stage behind...

By the way the wadia cd player gives 50db of output could that be of help in choosing amp

chef de gaar amp is one niece piece of engineering , and why not - he obviously learned from the finest

you'll not make mistake if you try to make one

there is no need for different output stage , except addition of power resistor , going from output to neg PSU leg - which will bring some SE bias ;

wadia : 50db ; comparing to what ?
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Old 4th November 2010, 07:57 PM   #194
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Zen mod
A little delayed reply,
Thanks so far for help. Im studying and trying to understand the numbers. Which i feel is nescesarry in order to make the right amp choice. And, for understanding what Im doing later on .
So this means i will probably be comming up with some (relativly simpel) questions soon .....


Just for now, concerning the Wadia 830 it says :

output 50 db in 100 0,5 db steps. output impedance lower than 15 ohm.
On stereophile test they state output voltage 0 to 4,25 volt.


Would this be enough to use only powerstage of ba-1 as is suggested in the article?
or do I need more voltage?
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Old 4th November 2010, 08:06 PM   #195
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by Alettagla View Post
.......

output 50 db in 100 0,5 db steps. output impedance lower than 15 ohm.
On stereophile test they state output voltage 0 to 4,25 volt.


Would this be enough to use only powerstage of ba-1 as is suggested in the article?
or do I need more voltage?

I'm pretty sure it will be enough
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Old 4th November 2010, 08:24 PM   #196
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Default Q201 Question

Hi,

I've got a maybe stupid question regarding Q201...
From what I've figured out so far, Q201 is biased with voltage of around 0.2V between Gate and Source without a signal applied. When a signal is applied, the voltages goes up or down some 0.1 volts or so, thus controling how the current is spread between the two paths to V-.
The only thing I can't figure out is how/why exactly the gate-pin gets fixed at around 0.2V below GND. Is this because of the internal resistance of Q202? And is this resistance really the same in every 2sk170?

I hope you can help me.

BTW: You may not have noticed, but I'm also building this amp...
At the moment, I'm waiting for the cases to be finished. I brought my blueprints to a friend of my father, who owns a metal processing company, but he is a bit slow... On the other hand, I think I can get them nearly for free, only paying for the aluminium...
Of course you'll instantly get some pictures as soon I've packed the boards and stuff inside the cases.

~ nightrush
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Old 4th November 2010, 08:35 PM   #197
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Thanks:
Makes my live easyer isn't it..
lesser components than other options
Probably most promissing option for optimum sound.
I guess valuable question is if there is any dc comming out of wadia (balanced) outputs


Now how could i get some more power out of this? Bridging or x-ing or.....?
(i want to stay with my 4 2x 18volt 500va transformers

And have about 0,15 kw of heathsink per mono channel available.
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Old 4th November 2010, 10:01 PM   #198
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by nightrush View Post
Hi,

I've got a maybe stupid question regarding Q201...
From what I've figured out so far, Q201 is biased with voltage of around 0.2V between Gate and Source without a signal applied. When a signal is applied, the voltages goes up or down some 0.1 volts or so, thus controling how the current is spread between the two paths to V-.
The only thing I can't figure out is how/why exactly the gate-pin gets fixed at around 0.2V below GND. Is this because of the internal resistance of Q202? And is this resistance really the same in every 2sk170?

....

~ nightrush
you wanna fish , or yo wanna go fishing ?

go to FIRST WATT HOME and download all pdfs you can find there

same - go to Borbely's Home Page , download all pdfs

read - and few things will be clearer

anyway - I think it's better answer than short "yes"



Quote:
Originally Posted by Alettagla View Post
Thanks:
......


Now how could i get some more power out of this? Bridging or x-ing or.....?
(i want to stay with my 4 2x 18volt 500va transformers

And have about 0,15 kw of heathsink per mono channel available.
if you're thinking about more power ........... just go and build Cheff's UP amp
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Old 5th November 2010, 02:32 PM   #199
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Quote:
Originally Posted by Zen Mod View Post
you wanna fish , or yo wanna go fishing ?

go to FIRST WATT HOME and download all pdfs you can find there

same - go to Borbely's Home Page , download all pdfs

read - and few things will be clearer

anyway - I think it's better answer than short "yes"
Hi ZM,

I've already checked Pass Labs and First Watt, but found nothing that could have helped me with my question.

Could you please give a little concreter answer?
How can I calculate the internal resistance of the mosfet? It varies with the varying Vds, which must be above the saturation voltage otherwise the jfet would be no ccs, but I can't calculate this voltage without the internal resistance, or can I? It's like trying to find the end of a circle...

Quote:
From what I've figured out so far, Q201 is biased with voltage of around 0.2V between Gate and Source without a signal applied. When a signal is applied, the voltages goes up or down some 0.1 volts or so, thus controling how the current is spread between the two paths to V-.
At least this is correct, if I got you right?

Downcast nightrush...

Last edited by nightrush; 5th November 2010 at 02:41 PM.
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Old 6th December 2010, 02:58 AM   #200
Chad is offline Chad  United States
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Finished preflighting my BA-1 tonight. Hooked up the speakers, I love the sound of this single ended amp. This is my first se amp. It sounds very good. I like it more than the BA-2 which sounds great also. I'm using axon caps at the moment. Figure in few weeks I'll put in some silmics and see if I can hear a difference. It took about 45 minutes for the sinks to come to temp and I seem to be able get offset pretty steady around 1 to 2 millivolts after it warms up. Once I tidy up the wiring I'll post some pics.

Next on the list is a F5. Then I'll take amp break and build some type of full-range speaker that will have medium WAF. Kinda waiting for the new Seas ($130) driver Papa's been playing with.


Papa again thank you for sharing your life's work.

Chad
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