AU-X1 question

Willy6

AK Subscriber
Subscriber
Does anyone know which to3p device is a good match for the original X-1 outputs?Right now I'm looking at the Sanken 2SB1560 and the 2SD2390 if there's a better match out there please advise..
 
Are you going to change just one? or a pair?.... or all of them?

It is best not to mix types of OP transistors - if you change one, you should change the opposite (PNP or NPN) one that makes up that pair. Then, because the AU-X1 uses multiple OP transistors in parallel, to avoid unbalancing the other 4 in that channel (3xNPN & 3xPNP per channel) you should change all of those as well.

And although it doesn't matter quite as much, with a statement piece amplifier like the AU-X1 you should really change all the transistors in the other channel too.

There are measures taken to 'even out' the potential differences in even OP transistors of exactly the same type - these are the presence of emitter resistors, and also the resistors in series with the bases of the OP transistors. Don't even dream about altering the values of those to account for the use of different transistors. :no:
 
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It is best not to mix types of OP transistors - if you change one, you should change the opposite (PNP or NPN) one that makes up that pair. Then, because the AU-X1 uses multiple OP transistors in parallel, to avoid unbalancing the other 4 in that channel (3xNPN & 3xPNP per channel) you should change all of those as well.

And although it doesn't matter quite as much, with a statement piece amplifier like the AU-X1 you should really change all the transistors in the other channel too.

There are measures taken to 'even out' the potential differences in even OP transistors of exactly the same type - these are the presence of emitter resistors, and also the resistors in series with the bases of the OP transistors. Don't even dream about altering the values of those to account for the use of different transistors. :no:
Right if I change one I change them all..Reason I'm asking is I recently acquired another AU-X1 with the onsemi Mj21194g and Mj21193g outputs in place of the originals and thought I might put the to3p devices in there instead..
 
Ah ok - I see, not a bad idea, I assume you will use the mounting technique, or similar, used by that guy with the AU-X11 that seemed to work so well?
 
Ah ok - I see, not a bad idea, I assume you will use the mounting technique, or similar, used by that guy with the AU-X11 that seemed to work so well?
Ya i was looking at that thread and might try a few ideas of my own.So do you think those above mentioned devices are a good choice?
 
Ya i was looking at that thread and might try a few ideas of my own.So do you think those above mentioned devices are a good choice?

Can't say - what devices did the AU-X11 guy use, you could use the same maybe?
 
Hello there,
I haven't done an AU-X1 (I wish, or even better an AU-X11 with feedforward!), but first off the devices you asked about don't seem appropriate - they are Darlingtons (two transistors in one package - think driver and output integrated).

Any amp that I have refurbished with TO3(P) devices I have used either the NJW0281/0302 pair or the NJW3281/1302 pair from On-Semi. The first pair are slightly lower power but lower input capacitance. Both sets have good fT, and excellent hfe linearity with collector current (= less rising distortion with increasing power level). They would be my choice.

regards

Angus
 
@ghamilton, they will work fine electronically, esp the 3281/1302 higher power pair, but they are plastic packaging, not the metal TO-3 cans. If you aren't bothered about retaining the stock appearance you could remove the sockets and fit them direct to the heatsink (sacrilege I know). If you want to use them in the sockets you will need to follow EW's thread.

regards

Angus
 
@ghamilton, they will work fine electronically, esp the 3281/1302 higher power pair, but they are plastic packaging, not the metal TO-3 cans. If you aren't bothered about retaining the stock appearance you could remove the sockets and fit them direct to the heatsink (sacrilege I know). If you want to use them in the sockets you will need to follow EW's thread.

regards

Angus
I don't need them, but I thought I would buy some on-semi cans that will fit for just in case. If they don't make the metal can type then never mind. Thanks
 
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