mcmelectronics carries them, but they are out of stock also. Who told you they were discontinued?
There are single versions of these (search the Dynahi construction thread for the numbers, can't remember offhad), but matching these might be a bit of a problem (although the dual packaged SK389 and SJ109s "matching" can sometimes leave a bit to be desired also).
Originally Posted by amb Pars, the separate versions are 2SK170 (N-channel) and 2SJ74 (P-channel). Since these are not formed on the same substrate you will see much more variations in Idss between units. To get good matches might require a fairly large number of them and a lot of time to test.
This was in the matched transistors thread. Fortunately the last time I checked, these were pretty cheap (much less than half the cost of a 2SK389).
The British (IIRC) company making a replacement doesn't seem to offer it in the same package, so might be fun getting them to fit.
Well, you're going to have imbalances, both between the two halves of that CCS, and the other side (the 2SJ109). You do understand that the 2SK is two of the 2SK170s. Read the thread on matching transistors and FETs. The FETs are really pretty easy and you can do it hand-held with a 9V battery and your DMM. You are putting lots of expensive little parts in this thing... might as well do it right. If you didn't want to match transistors and FETs, you probably picked the wrong amp to build.
That said, Ermo Borbely (borbely audio) sells matched pairs of 2SJ109s and 2SK389s. Shipping will be from Germany (IIRC). Check here... go to Audiophile Components and download the .pdf price list. Won't be cheap, but probably cheaper than buying 2-3 of each dual and getting a matched pair out of them.
I'm checking with a few sources to see if they have any and what class they are if they do have them. May end up ordering a handful. Let me know if interested and I will let you know if I get any luck.
Waiting for bdent to get more A1015 so I can order them and the C1815 (trying for GL class). For some reason I only ordered 24 of each a long while ago when I had the chance.
Held up by Mouser cause they are out of stock on the RN60 3.3K resistors.. figures.
Originally Posted by sbelyo I'll match them, it's just my least favorite part.
I found some 2sk389's but they are $17.50 each. At that price people must know they are discontinued.
Gawd, no kidding!!! I think I paid ~$4 for mine from MCM on sale. I thought the ~$12 something I got on a google hit was bad! I would think you could get a matched pair from Borbely shipped for about the price of 1 of those.
Linear Systems is willing to sell its LSK389 directly in low quantities; the price quote I got from them was reasonable, in the four dollar range if I recall correctly. They seem to have a different package than the 2sk389, and the specs are 'improved' over the older part. I don't know enough to say whether this would require any changes in a circuit or affect its performance in any way.
Originally Posted by dgardner The 2SK389 is not a lost cause yet. I am attempting to get a pile from some trustworthy brokers. I will share what I get with the headfi users at no profit... BTW, I have hundreds of 2SJ109 parts.
Man, your the one hording all the SK389's and SJ109