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Old 22nd March 2010, 10:31 AM   #7491
sekess is offline sekess  United States
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Quote:
Originally Posted by jacco vermeulen View Post
Good for you, i certainly did not.
Hey Jacco,
When I said I got it now, I meant Andrew's post. I was in a hurry and did not have time to elaborate.
For some reason, initially, only the top portion of his post came through. I uderstood what he said. But, I did not understand how the current draw is different between the balanced and bridged versions (for the same impedance loads).

Thanks,
Steve
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Old 22nd March 2010, 01:46 PM   #7492
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Quote:
Originally Posted by EUVL View Post
Are they matched at room temperature or at steady state on heat sink ?

Curve tracer matched Quad Comps are a must for those serious builders for Xed F5.

Can your curve tracer output data in digital format for post processing ?


Patrick
Room temp, which is cool.

The device does not heat much during test, unlike a static bias test jig.

I could let them cook for a while (actually I did... on a few to look at the change) but my experience with the Hitachi's is that there isn't a whole lot of difference in the spread when tested warm or cool. The pix from Luvdunhil's posts when he was selling them shows the same thing... fwiw. No worries, mate! ;D

this is an older Tek 575, no digital anything. Toobes to test tranzeesterz!!

Yes, for the X5 or the CViller boards having the devices on each rail very close is important...

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Last edited by bear; 22nd March 2010 at 01:48 PM.
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Old 22nd March 2010, 08:32 PM   #7493
tinitus is offline tinitus  Europe
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I was told that theres no matching of NPN to PNP
Matched pairs are 2x matched NPN, and 2x matched PNP

So, fore F5 with single pairs theres no need fore matching

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Old 22nd March 2010, 10:15 PM   #7494
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Quote:
Originally Posted by tinitus View Post
I was told that theres no matching of NPN to PNP
Matched pairs are 2x matched NPN, and 2x matched PNP

So, fore F5 with single pairs theres no need fore matching

Correct.
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Old 22nd March 2010, 10:46 PM   #7495
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by bear View Post
I only have a few sets for sale in the swap area...

First come first served.
If the demand is huge, I can go and buy a really large batch...
Post there, not here.

there is here:
TOSHIBA MOSFETS

Awayne, out of this batch there was no possibility to find the number that you wanted. Zilch. I would need a batch of 200-400 per type to find the number you wanted...

So, post up if you want them, even if I run out (and I will, there aren't that many to begin with...) otherwise I won't want to go out and buy several hundreds of each type myself.



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Yes i need as we previously discussed , so go ahead and let me know ....
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Old 22nd March 2010, 11:00 PM   #7496
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Quote:
Originally Posted by tinitus View Post
So, for F5 with single pairs there's no need for matching
This is true. However, if you know what you are looking
for, there's nothing that beats socketing parts and swapping
them in and out until you get what you want.

Currently I do this with J2's, as I have not found a matching
pattern that easily predicts performance. Of course this also
has to be done at temperature.

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Old 23rd March 2010, 12:12 AM   #7497
sekess is offline sekess  United States
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Default Sockets

That's an excellent idea -- does anyone have a part number for TO-247 device or similar?

Thanks,
Steve
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Old 23rd March 2010, 01:48 AM   #7498
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Quote:
Originally Posted by tinitus View Post
I was told that theres no matching of NPN to PNP
Matched pairs are 2x matched NPN, and 2x matched PNP

So, fore F5 with single pairs theres no need fore matching


I wouldn't say that exactly.

I'd bet with a big lot of P & Nch maybe 1000pcs of each there would be a few dozen or so that would end up being dead on or nearly so in the center of the "sweet zone" - that being the overlap of the bias points...


Not having had enough in my hands of the Tosh's I can't say for sure how they usually end up. The old Hitachi metal can J49 & J56 (iirc) and their complements were overlapping to a small degree... I was able to find some that were dead bang on, but they did not have (allegedly) matching transfer curves as do the Tosh's...

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Old 23rd March 2010, 02:13 AM   #7499
tinitus is offline tinitus  Europe
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Ok, I just wondered about your batch #3#
Just one single set of matched pairs
One channel bought as a stereo set
Matching makes the 2 pairs cost more than common commercial unmatched devices
Maybe a mistake, but it seems pointless
In fore a refund ?

If you had split your matching up in ALL martched pairs, instead of matched quads, you might have gotten more and better matches, and cheaper
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Old 23rd March 2010, 03:12 AM   #7500
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It doesn't work that way tinitus...

The way I did it was to characterize all the devices without regard to where it was going to go. Then I looked at them. My interest was to get good matches for my own Cviller boards, even if I build them up as std F5, at least to have enough devices.

So after looking at the groups it became immediately obvious that there were a number of very lucky "quads" in both N & P. Knowing that some people want to make Cviller boards I offered them up as N + P quads.

The advantage of quads is that the bias points on both channels of the F5cv will bias at exactly the same point. Since NP has stated that the bias point effects the harmonics and the way the amp sounds, this way one is assured of having two channels that are indeed so similar as to be deemed identical in this regard.

If you build without each gender of device being the same Vgs between two channels, maybe not such a big deal, maybe is... but in the F5cv build it becomes important because the devices are running in parallel.

All in all it is merely closer to some degree of "perfection".
Not necessary at all to make the amp run, but also not a bad idea if you are trying to optimize.

And, yes, matching costs more than unmatched common commercial devices... there is time and effort involved, plus the outlay of cash to acquire a sufficient number of devices to arrive at a match...

I guess it all depends on what you think is important or what you want...

No one is obligated to buy anything?
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