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Old 29th October 2013, 09:21 AM   #201
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@lemon:
thanks for your contribution. I agree that it is certainly better to correctly match the JFETs and I am working on this together with miniDSP. So I am quite sure that the DACs will soon be available again with well matched FETs.

If you want to match on your own using an Atlas DCA Pro with curve tracing function will surely give very good results.

I matched the FETs with respect to IDSS using this Page and it works perfectly for this circuit. The MMBFJ310 do not neccessarily need matching (DC offset will be only a few mV if they are not matched) but the BF862 should be matched with +/-0.2mA or better.

regards, Daniel
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Old 30th October 2013, 10:19 AM   #202
lemon is offline lemon  Greece
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Daniel thanks for the reply.

It is very positive announcement that the Curryman dac is available again with well matching the jfets!

I was to dillema what to do, to buy some jfet and matching them or to put the R2 and pot to the right position of designer (Joachim).
Finally, I decided to order some jfet and matching them.

From what I see, there is a changed at MMBFJ310 with the MMBFJ111 to Joachim Gerhard Filter Buffer thread.
Do you know what is reason for that? Is it some upgrade or for availability reasons?

Last edited by lemon; 30th October 2013 at 10:22 AM.
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Old 30th October 2013, 06:46 PM   #203
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Quote:
It is very positive announcement that the Curryman dac is available again with well matching the jfets!
just a minimal correction to avoid missunderstandings: will soon be available again

The original buffer design from Joachim used MMBFJ310 and for the JG filter buffer GB it was changed to MMBFJJ111. e.g. EUVL can surely better explain the reasons. I discussed the schematic with Joachim during the "development" and desided to use his original design. However both perform very well in this buffer, no need to worry
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Old 6th November 2013, 06:39 PM   #204
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Here we go again...... Why is there always so many corrections with the miniDSP products?
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Old 11th November 2013, 02:36 PM   #205
syklab is offline syklab  Hong Kong
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Hi Daniel,
Will the DAC be available again soon ?

Thanks
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Old 12th November 2013, 11:26 AM   #206
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Yes, should be available again within the next two weeks
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Old 13th November 2013, 03:28 PM   #207
Can you say Audio?
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Location: Greenwood Village, Colorado
Well, I think because it takes a lot of time, effort and cost for a small group of individuals to pull off commercial DIY product(s). They're dependent on small assembly shops, etc. Each time the shop or supplier screws up, I suspect that all involved are eating the cost of the whatever needs to be redone.

We all want it right the first time, but honestly - I get why many who are capable of making their designs available, don't. If something goes wrong (your fault or not) buyers can be very unforgiving.

Sorry - not really targeted at you damuffin; just think we all need to get our minds right about how to support small audio efforts. It'll cost us a bit in patience, but for it we get access to some very leading edge kit.

Quote:
Originally Posted by damuffin View Post
Here we go again...... Why is there always so many corrections with the miniDSP products?
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Old 15th November 2013, 04:40 PM   #208
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Hi curryman,

I've received my dacs this morning. The build is clean, if they sound as good as they look I'll be one happy man

On my PS I have the choice beetwen +/- 12 or 15v. What is the best voltage between these two for the buffer stage?
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Old 16th November 2013, 06:35 PM   #209
lemon is offline lemon  Greece
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Quote:
Originally Posted by curryman View Post
@lemon:
thanks for your contribution. I agree that it is certainly better to correctly match the JFETs and I am working on this together with miniDSP. So I am quite sure that the DACs will soon be available again with well matched FETs.

If you want to match on your own using an Atlas DCA Pro with curve tracing function will surely give very good results.

I matched the FETs with respect to IDSS using this Page and it works perfectly for this circuit. The MMBFJ310 do not neccessarily need matching (DC offset will be only a few mV if they are not matched) but the BF862 should be matched with +/-0.2mA or better.

regards, Daniel
Finally, I used the Atlas DCA Pro and I measured 20 of BF862 by Vgs (on) and Id. I matched 4 of them (3 of them was just and the 4th was very close to them).
The old values was -63.13mV and 51.18mV.
Now the values is -0.12mV and -11.2mV and I am OK.
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Old 20th November 2013, 02:31 AM   #210
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Hi Daniel,

just ordered three of your DACs to add to miniSHARK

Looking into powering options, got interested in the SPMS solution JG is using. For three DACs I'd probably go for the 30W version, My question is, would the filter need some modification in this case?

Thanks you,
Abel
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