Some other Source Follower COnfigurations - Page 6 - diyAudio
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Old 26th September 2008, 06:53 AM   #51
EUVL is offline EUVL  Europe
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Default DAO TCS as Power Amp ?

To use the circuit as power amp, you need to reduce the source resistor of the LU1014 to 0.67R and set the cascode the same way as Zen V9. 3x LU1014 in parallel will require 4A bias and have a output impedance of about 0.3R, which is sort of high, even when combined with the Taylor Current Source.

There is no simple way to reduce this in a follower circuit. That is why I did not post such a circuit to drive speakers.


Patrick
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Old 26th September 2008, 03:24 PM   #52
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>Of course one can use two DAO TCS in balanced mode, which will easily reduce even harmonics by a factor of 10 if the devices are well matched. But that is a no-brainer.


Just curious could the negative input be grounded to get balanced outputs or does it need to be driven with a balanced source?

Sean
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Old 26th September 2008, 03:47 PM   #53
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It is a follower, so it will just follow the input, even if it were Gnd.
i.e. You need a balanced source.


Patrick
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Old 6th October 2008, 07:09 AM   #54
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> To use the circuit as power amp, you need to reduce the source resistor of the LU1014 to 0.67R and set the cascode the same way as Zen V9. 3x LU1014 in parallel will require 4A bias and have a output impedance of about 0.3R, which is sort of high, even when combined with the Taylor Current Source. There is no simple way to reduce this in a follower circuit. That is why I did not post such a circuit to drive speakers.

A member of the forum was discussing with me off line about using the DAO TCS-X as power amp :

http://www.diyaudio.com/forums/showt...58#post1613058

The comment about the source resistor still applies. But with the Taylor current source, the output impedance will be reduced by half to around 0.15R. This is not far off that of the F4 circuit, as the LU1014 has somewhat higher transconductance at 1.3A than IRFP240. The values of R1,2,3,4 would need some adjustment, depending on how many FETs in parallel. I am out of town right now, so this will have to wait a couple of weeks. But judging from Steen's results and my simulations, this will give the F4 a run for its money, especially the X'ed balanced version (with 12 LU1014s and 12 IRFP240 as cascode).


Patrick
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Old 9th October 2008, 02:34 PM   #55
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Oh Dear!
Patrick, or somebody - could you help to tell me how to open the zipped ccts on post 4, 77, and 48.
The discussion is a bit vague without the Ccts!

Not very "clued-up" about computers, I'm afraid - I end up getting told to copy it into temporary files, etc but just won't open. Frustrating!!
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Old 9th October 2008, 02:42 PM   #56
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I don't understand your problem.
Don't you have winzip ?
If not I am sure you can get a free download somewhere.
After you unzip, it is actually a Word document.

I have not heard anyone else having problem except for those who use Linux.

Maybe someone else knows better.


Patrick
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Old 9th October 2008, 02:58 PM   #57
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Sorry, didn't mean to create problems - it appears the "winzip" package isn't functioning, just like my brain!! - I seem to have a knack for creating computer glitches! - will sort it out tomorrow

Thanks again.
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Old 13th October 2008, 12:39 PM   #58
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Default Opening

Thanks Steinoe for your help in sorting out problem - Ccts are very clear.
Thanks too, Patrick.

Now, to mate this up to the Lightspeed ....
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Old 13th October 2008, 03:45 PM   #59
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> Now, to mate this up to the Lightspeed ....

You would need one of the simple JFET buffers at the beginning of the thread, for the LU1014 has relatively high input capacitance, and a 100k passive attenuator is probably not the best direct match.


Patrick
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Old 13th October 2008, 11:47 PM   #60
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Looks a perfect match - simple, common p/supply, good sound, etc.
The Aikido does has that valve magic/colour altho' more complicated.

Tks.
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