drivers matching

bigpanda · 10th May 2006, 04:48 AM

Hi,
I have heard about drivers matching but have no idea how to do that. Do we match them by matching the hfe? Since they will be PNP-NPN pairs, will the hfe be close?

Tks for your help

bigpanda · 12th May 2006, 12:09 AM

anyone / anything at all? please.

anatech · 12th May 2006, 12:14 AM

Hi bigpanda,

Quote:

Do we match them by matching the hfe?

Yes. That's how I do it.

-Chris

AndrewT · 12th May 2006, 01:34 PM

Hi,
I wonder if trying to match both hFE and Vbe would help?

The big problem will be finding drivers where the gain of both the NPN and PNP pairs are similar. Good selection by the manufacturer may help here but equally could make matching even more difficult.
If all the PNP are towards to bottom end of the gain range and all the NPN are towards the top of the range then you may never find any matches.

anatech · 12th May 2006, 01:40 PM

Hi Andrew,
I generally ignore Vbe. hFE is more important (in my opinion anyway) since the devices are already conducting. I tend to use certain device families to match NPN and PNP gains. You're correct in that sometimes this is not possible. You just do the best you can.

Japanese parts were often better in that regard.

-Chris

bigpanda · 12th May 2006, 05:23 PM

The worst nightmare would be : the same batch no. are close in characteristic. Iif you buy a bunch of the two and if the first few paris dosen't match, you will have a thin chance of matching any pair at all for the rest of that particular purchase. Would that be true? How important would it be to do matching? I mean in general.

AVWERK · 12th May 2006, 11:38 PM

Last night I recieved some more MPS 42/92's to finish the last 3 monoblock KrellKlone 50's.

The first 2 HFE sets were around 136/137... About as good as your going to get with 12 pcs. DC offset I can set within 2 mv no problem with little movement of value.

The 50/50 pcs. I went thru last night were MPS 42 all around were about 85 to 95 HFE
The 92's were all up around 140 to 170 HFE...

I guess I'll try the Toshiba's 2sa970/2240 I have left over from a previous pair I built some years ago...

David

anatech · 13th May 2006, 12:39 AM

Hi bigpanda,
It depends on the distribution and how tight things are. I always measure every single one.

Makes Chris a dull boy some days, let me assure you.

David,
You may have better luck with the C2240 and A970. Depends on whether they are mixed batches or not.

-Chris

bigpanda · 13th May 2006, 03:11 AM

All I can understand about the situation will be :

If you want to have 2 matched pairs, You have to buy pairs of different batch # of Ps and Ns, hoping that they can be matched. In the end, you may waste about 20-30 (hopefully) to get 2 pairs matched and if you are not lucky enough, you might never get any match at all !!!!.

Is there anything we can do instead of just trying our luck (or wearing out our patience, wallet, labor). For the input pair, there is something we can do, (as I can understand from Quasi's Nmos 6 IRFP450). can the same (or similiar) be done for the drivers?

Tks

anatech · 13th May 2006, 04:15 PM

Hi bigpanda,
You need to purchase complimentary pairs that have a history of close gains. That means forget doing this with MJ15003 / MJ15004 for example. It may not be possible to get complimentary matches. If not, just smile. Life isn't perfect.

-Chris

10th May 2006, 04:48 AM	#1
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	drivers matching Hi, I have heard about drivers matching but have no idea how to do that. Do we match them by matching the hfe? Since they will be PNP-NPN pairs, will the hfe be close? Tks for your help

12th May 2006, 01:34 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, I wonder if trying to match both hFE and Vbe would help? The big problem will be finding drivers where the gain of both the NPN and PNP pairs are similar. Good selection by the manufacturer may help here but equally could make matching even more difficult. If all the PNP are towards to bottom end of the gain range and all the NPN are towards the top of the range then you may never find any matches. __________________ regards Andrew T.

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12th May 2006, 12:09 AM	#2
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	anyone / anything at all? please.

12th May 2006, 01:40 PM	#5
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Andrew, I generally ignore Vbe. hFE is more important (in my opinion anyway) since the devices are already conducting. I tend to use certain device families to match NPN and PNP gains. You're correct in that sometimes this is not possible. You just do the best you can. Japanese parts were often better in that regard. -Chris

12th May 2006, 05:23 PM	#6
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	The worst nightmare would be : the same batch no. are close in characteristic. Iif you buy a bunch of the two and if the first few paris dosen't match, you will have a thin chance of matching any pair at all for the rest of that particular purchase. Would that be true? How important would it be to do matching? I mean in general.

12th May 2006, 11:38 PM	#7
AVWERK diyAudio Member Join Date: Jan 2004 Location: OC,Calif.	Last night I recieved some more MPS 42/92's to finish the last 3 monoblock KrellKlone 50's. The first 2 HFE sets were around 136/137... About as good as your going to get with 12 pcs. DC offset I can set within 2 mv no problem with little movement of value. The 50/50 pcs. I went thru last night were MPS 42 all around were about 85 to 95 HFE The 92's were all up around 140 to 170 HFE... I guess I'll try the Toshiba's 2sa970/2240 I have left over from a previous pair I built some years ago... David

13th May 2006, 12:39 AM	#8
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi bigpanda, It depends on the distribution and how tight things are. I always measure every single one. Makes Chris a dull boy some days, let me assure you. David, You may have better luck with the C2240 and A970. Depends on whether they are mixed batches or not. -Chris

13th May 2006, 03:11 AM	#9
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	All I can understand about the situation will be : If you want to have 2 matched pairs, You have to buy pairs of different batch # of Ps and Ns, hoping that they can be matched. In the end, you may waste about 20-30 (hopefully) to get 2 pairs matched and if you are not lucky enough, you might never get any match at all !!!!. Is there anything we can do instead of just trying our luck (or wearing out our patience, wallet, labor). For the input pair, there is something we can do, (as I can understand from Quasi's Nmos 6 IRFP450). can the same (or similiar) be done for the drivers? Tks

13th May 2006, 04:15 PM	#10
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi bigpanda, You need to purchase complimentary pairs that have a history of close gains. That means forget doing this with MJ15003 / MJ15004 for example. It may not be possible to get complimentary matches. If not, just smile. Life isn't perfect. -Chris

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