Aleph Ono Project (from PCB group buy)

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TheMyxin

Member
Joined 2003
pquadrat said:


As far as I know, You should (at least) match the four JFETS of the MC stage, and the two IRF9110 (Q21, Q22) in the inverter. You can find info about MOSFET matching on www.passdiy.com .
For the JFET matching, I got a document
from Jens, it is attached as a jpg.


Is it opssible to use a 12 Volt DC Power-
Supply or Battery for JFET/MOSFET-
MAtching instead of 15 Volt DC (I think yes) ?

What about Q8 and Q19 ? Are they need also a Matching ?

The other JFET/MOSFET dont need
matchings right ?
(As i read the Nelson-Articel about
MOSFET-Matching) ?
Click to expand...
 
SvErD

SvErD

Member
Joined 2002
I've received the boards aswell, excelent job Peter!:up:

I have problems to source some of the components though. The 9110 I haven't found anywhere, the 2SK170BL and 2SK389 I can get from Broberly, but costly. Any suggestions?

I'm also planning the following substitutions:
2SC2240 replaces 2SC1844
2SA970 replaces 2SC991
BC639 replaces ZTX450
Any comments?
 
Raka

Raka

Member
Joined 2002
Me too!

I received them too, thanks a lot! They look awesome...

I have some questions about the sourcing, I will try to get all my questions to ask in only post.

Any suggestion about the resistors, I don't know where to get Dale in europe, any hint?
 
patriz

patriz

Member
Joined 2002
lencohell.wordpress.com/
SvErD said:
I've received the boards aswell, excelent job Peter!:up:

I have problems to source some of the components though. The 9110 I haven't found anywhere, the 2SK170BL and 2SK389 I can get from Broberly, but costly. Any suggestions?

I'm also planning the following substitutions:
2SC2240 replaces 2SC1844
2SA970 replaces 2SC991
BC639 replaces ZTX450
Any comments?
Click to expand...

You can get 2SK170 and 2SK389 here:
http://www.grandata.co.uk/
http://www.schuro.de/japan-dat.htm
http://www.buerklin.com/
then I found this site that appear to have a huge semiconductors catalog but I can't understand what language they speak and how they work, if someone can help will be welcome:
http://www.stuutenbruin.com/compo.html
Giorgio
 
P

pquadrat

Member
Joined 2002
Re: Ono PCB-Boards

TheMyxin said:
Thanks a lot the boards arrivied here to.
Minor Bug i have found at the morning
On C20 C12 there ist the Plus-Sign
missing for the Electrolytic Caps but
its not so difficult to find the GND-side
on the PCB for the caps.


Question:

For what is the JP3 ?
Click to expand...

You are right, on C12 and C20 the plus sign is missing. But orientation is the same as the other electrolytics.

With JP3 You can connect the shielding planes to ground. You can solder a wire if You want it to ground. I made it to see if the ground plane has any effect.

-peter
 
Raka

Raka

Member
Joined 2002
Parts....

Well, this is not again the very same question about parts, (it's more or less the same question...)
I've read a lot of posts about the highest parts quality differences between "esoteric" brands, if any, I'm not asking about this. I wonder if the very standard parts in resistors and caps will bring the performance to a medium-low fi.
Have anyone tried a quality design with the very cheap parts??
I don't know if a standard metal film resistor can hold the dale's...
 
T

TheMyxin

Member
Joined 2003
mjounot said:
Peter

Thanks very much for the boards.
the quality is much appreciated.

What is min. watt rating for R-43,44,70,71


Hello Mike.
I have put in 2 Watt Metalloxid Resistors in my PCB-Board.

Another question for the PCB-Board. As i have seen on Peters
Photos there are no heatsinks on the MOSFETs. right ?
On a photo in the "Audio" magazine 11/2002 i have also not seen any heatsinks for the MOSFETs. Only on for the voltage regulators
(7815 on the PCB-Layout is written)
Click to expand...
 
T

TheMyxin

Member
Joined 2003
Again Matching Question

As Peter write here its important to match the four 2SK170 JFETS
at the Beginning of the MC-Stage. Question how much is allowed
in variation of the voltage across the measure-Restors (As posted
in Peters Picture for matching N-JFETs) ? I have found 4 pairs
which vary only ca. 2 mV and that seems to be very good and
due to a "flying" circuit-measurement the error of the measurement is for shure higher ?
But what about variations with 10 or more mV ?
At which varation its not so good (first from the security
point of 4 parallel current-follower as i understand the
circuit right ? and second for audiophile reasons ?)

Second problem is that i think its important to measure all 4 pairs
at the same time and at the same temperature if possible.
So when i have put my fingers on the JFET for wiring i have
wait ca. 1 min. during each measurement to be sure that the
JFET has the same room temperature. This avoids IMHO temperature drifts in the semicondutors right ?
Third when i have notice the voltage on my digital-voltmeter
i have wait until the value become constant and/begans slightly
to drop and go up. This seems to me the best measurement ?



Another Question what is with Q1 and Q2. Matching nessecary ?
 
T

TheMyxin

Member
Joined 2003
coffin said:


I also check the chart on datasheet to figure out that the noise will be smaller when the current is larger in some degree.
SO......BL is right?:

I think this link will help very much (i have get from a Usenet-
Member)

http://ken-gilbert.com/images/pdf/erno_borbely_on_jfets.pdf

There is also described the differences between the 2SK170
types GR,BL and V-type in short and some more Measurement
Infos on JFET-Matchings.
Click to expand...
 
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