nice one, thanks.
Can I check with you guys about measuring Idss of jfets like the 2k246y? I have 4 here to check.
I understand I can use a 9v battery and connect the gate and source to gnd, then measuring the mA load between battery pos and drain. Does that sound right?
I've seen mention of using a resistor inbetween battery pos and drain, and using a meter to measure the voltage drop and calculating the mA load from that. Is there a reason not to just switch the multimeter to Amps mode and putting it in line between batter pos and drain?
thanks,
James
On a slightly different note, the USB plug is not very reliable, and will give issues for the application we are using them for, I doubt there is any of the good stuff like error correction or checking in the ASIO/WASAPI drivers.. I've noticed the occasional crackling noise, which can ben remedied by reseating the USB interlink. I'm seriously thinking about going for a better connector type for the USB connection. Something like SN-8-4 by Evalucon. ( http://www.evalucon.com/images/sn.pdf). A lead could even be soldered straight onto the WaveIO board.
Why should I have to call him to check up on an order when I've a)waited two months and b) e mailed him?
As I said in contrast Belleson despatched at 8am their time next working day!
Guido should be phoning me, not the other way round!
It is a shame there are so many prima donnas in the world of audio DIY.
I gave up on trying to get regs from TENT. Maybe he made so much money when he was the toast of the town that he spends his time on a sailing yacht in the Mediterranean these days? If so, I am happy for him but he should make it clear that his new business model is to ship stuff when the mood strikes ... and not a moment before.
Brian and Christina Lowe treat people the way they like to be treated. It does make for a very pleasant difference.
(By the way, BELLESON will be introducing a super-regulator for power amplifiers at RMAF this week. Max output - 100 volts - 10 amps)
The gap between series and shunt regs has narrowed to the point of it being a matter of taste. Nothing is perfect, anyway.
Series regs will, usually, produce more accurate bass and the shunts, usually, have an edge in the high frequencies. The mids are a toss up - which sound do you prefer?
Hoping the battery route will allow the best of both worlds.
Cannot find anyone to attach tabs so I ordered some aluminum solder paste and hoping I can make it work. I feel sure, if it does work, my use of copper tabs will be superior to nickel.
On the subject of prima donnas we are lucky that Mr. Douma is NOT one of those!
A question for Doede - for those who want to use the new mainboard but have no interest in SPDIF input - will the BLUE board be available without the unneeded TENT clock?
I have asked AUDIO CREATIVE and have not heard back.
Don't want to go the heroic route with the extra little boards and wires ...
Please tell me this will be available!
Thanks,
A question for Doede - for those who want to use the new mainboard but have no interest in SPDIF input - will the BLUE board be available without the unneeded TENT clock?
I have asked AUDIO CREATIVE and have not heard back.
Don't want to go the heroic route with the extra little boards and wires ...
Please tell me this will be available!
Thanks,
Quite agree! The folk at Audio Creative ste normally very attentive too!
Measuring Idss of jfets
It depends on how sensitive the MA range is on your meter since you will be measuring less than 3ma. You can also put a 100 ohm resistor between the battery + to the 2SK246Y. The voltage drop should be less than 0.3VDC which will have a negligible influence on Idss for the purpose of testing and selecting JFETS for a CCS application.
It depends on how sensitive the MA range is on your meter since you will be measuring less than 3ma. You can also put a 100 ohm resistor between the battery + to the 2SK246Y. The voltage drop should be less than 0.3VDC which will have a negligible influence on Idss for the purpose of testing and selecting JFETS for a CCS application.
If I'm not mistaken, all the people I know who have used an unregulated PS with chokes for the DDDAC have gone for LCLC configuration.
Got 20 2sk246y's
I had to use around 1.8k resistor
Anyway not that impressed with sq
Will burn in more before final judgement
Not that it's bad just not what I'm looking for
Need to try 2sk170 bl version
Gr version using too high a resistor value
Must try the diodes again too
I had to use around 1.8k resistor
Anyway not that impressed with sq
Will burn in more before final judgement
Not that it's bad just not what I'm looking for
Need to try 2sk170 bl version
Gr version using too high a resistor value
Must try the diodes again too
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Thanks. I'll test them shortly and report back.
In theory, being the 'Y' type, they should all be 1.2mA to 3.0mA according to the datasheet. Am I just looking for the lowest ones or confirming that they're actually less than 3.0mA?
Sorry to hear people having bad experiences with Tentlabs. This sounds exactly my experience too. Placed an order, wasn't told there would be any delay, weeks of not knowing and having no replies to my emails, then after some weeks my stuff turned up and all was well. Great products, but real crappy customer service. I think the thing that frustrated me the most was actually how easy it would be to just let me know what was going on. I know the 8v shunts are a custom special order, but it's no real trouble to say 'thanks for your order. by the way, it will be 3 weeks to produce your items'. Then everyone knows the score and what to expect.
. Let me check and I will post back, ok?
Today I give a call to Guido asking about my order... I also explain to him that many of us in the forum are really upset about his way to deal with us as customers. He recognize his lack of communication and he give me his apologize... I hope was not just kind words.
Regards,
Enrico
Good work Enrico. I have great respect for Guido's work and I really want him to do well. I hope he can work on this communication issue.
This evening I have measured the Idss of the 2SK246Y JFETs which I'm going to try next for the pin20 current source.
It's a simple job, but not one I've done before, so I had to do a little searching to find out how. Hopefully the following pictures help explain the method for anyone else interested in trying this
This evening I have measured the Idss of the 2SK246Y JFETs which I'm going to try next for the pin20 current source.
It's a simple job, but not one I've done before, so I had to do a little searching to find out how. Hopefully the following pictures help explain the method for anyone else interested in trying this
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Correct me if I'm wrong, but it sounds like you're trying to measure the Idss at our 2.4V "voltage drop of interest" - but this is not how Idss is measured (I will draw, scan and include Borbely's rig for such measurements in a ulterior post).
If you are measuring this "Idss" under a certain threshold - Vgs(off) -, you're not even running the JFET in the so called "current-limited mode," or "the current saturated region," which is what's needed for making it a CCS. I believe the JFET is in that region run as a "transconductance amplifier," and I have no idea what that does to pin 20, but it's not constant current sourcing. We need to understand this to choose the correct part for the job.
(one of the reasons that this series resistor is used for measuring the current via voltage drop and ohm's law is that it is non-circumstantial due to what I am saying above)
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