[sdiy] Analog MAT12 matched NPN pairs // LS358

mark verbos mverbos at earthlink.net
Mon Jun 2 02:41:19 CEST 2014


I use Linear Systems LS311 pairs in my Buchla format oscillators and I use SMT lm3046's in my Euro stuff. 
I don't have a problem with either. And, I don't have hi frequency trims.
Mine are all triangle cores, which tend to be more forgiving of the hi frequency thing due to the reset time on a saw core.

Mark



On Jun 1, 2014, at 4:34 PM, Tom Bugs wrote:

> What is the view of devices like the LS358 from Linear Systems?
> (http://www.linearsystems.com/ or http://www.linearsystems.com/assets/media/file/datasheets/LS358.pdf)
> 
> These aren't actually too hard to source now (though no mouser etc) - think you can get direct off LS in the US, but over this side of the pond you can try
> https://www.micross.com/ecommerce/shop-default.aspx
> These guys, Micross, now do online ordering & despite long(ish) lead-times listed on the site they often have a few in stock.
> Various packages, happy with small orders - good & helpful.
> 
> There are other interesting transistor pairs from LS too.
> Good things:
> - they seem to be great quality devices (pros commenting on these areas would be good though..) but not too ridiculously priced & not too hard to source.
> 
> Ta, Tom
> 
> On 01/06/2014 20:54, Jay Schwichtenberg wrote:
>> These are a lot cheaper and will work.
>> 
>> http://synthcube.com/cart/index.php?route=product/product&path=74_18&product
>> _id=162
>> 
>> There has been a lot of talk about how regular transistors matched are good
>> enough. I can see that for filters but I'm wondering about for VCOs. One of
>> the parameters that isn't mentioned anymore is rBE which can cause errors in
>> the exponential converter. This is mentioned in Electro Notes and on Rene
>> Schmitz's web site (http://www.schmitzbits.de/expo_tutorial/index.html). At
>> one point this was one of the reasons the expensive transistor arrays were
>> used. Rene's web site mentions that this can be compensated for if high
>> frequency trimming is put into the exponential converter. But still having
>> to trim something out seems wrong if you can avoid it. Also maybe picking
>> transistors that have a low rBE (which typically is NOT speced for a
>> transistor) would be better than the old 2NXXXX and BCXXX standbys.
>> 
>> Comments/discussion?
>> 
>> Thanks for the bandwidth.
>> Jay S.
>> 
>> -----Original Message-----
>> From: synth-diy-bounces at dropmix.xs4all.nl
>> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of john slee
>> Sent: Saturday, May 31, 2014 6:48 PM
>> To: Synth DIY
>> Subject: [sdiy] Analog MAT12 matched NPN pairs
>> 
>> I think my MFOS modular PCBs arrived at work last week. I was
>> originally planning to match 2n3904s and cuddle them up in goo
>> and heatshrink, but these caught my eye as I was browsing Mouser
>> for VCO parts...
>> 
>> http://www.mouser.com/ds/2/609/MAT12-246314.pdf
>> 
>> Comments? They're quite expensive ($30+ each even in /10 qty)
>> but OTOH I don't need that many, and they're in nice shiny metal
>> cans, they're available, and they're already matched. Worth it?
>> 
>> John
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