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TSSA V1.6 docs and buyers list

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#232
6n
2p
If this messes up your matching, I am willing to pay extra. I just dont want to have to buy in qty necessary to match for such a small amount. Hoped you might have some already.

THis may sound stupid, but do you like the input bjt's that you used in this amp? I am buidling a littel BJT based preamp and looking for alternatives to ZTX450/550. Would really like SMD parts that are well suited for audio. I am new to bjt's
 
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#233
buzzforb said:
6n
2p
If this messes up your matching, I am willing to pay extra. I just dont want to have to buy in qty necessary to match for such a small amount. Hoped you might have some already.

THis may sound stupid, but do you like the input bjt's that you used in this amp? I am buidling a littel BJT based preamp and looking for alternatives to ZTX450/550. Would really like SMD parts that are well suited for audio. I am new to bjt's
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No problem.

If i would give you an advice, it would be to stick with the following parts. They are easy to get and has an good performance.

They are well suited for low to mediumhigh source impedance. the hFE linearity is good, stray capacitance is low (Which is very good as it is very unlinear), noise level is okay, Ft is high.

BC846B/C, BC856B/C (65V)
BC850B/C, BC860B/C (45V)
BC847BS, BC857BS (45V) (dual)
BC846BS, BC856BS (65V) (dual)
BC847BPN (45V) (NPN and PNP in one package)

Matched variants:

BCM847BS, BCM857BS (45V) (dual) (vbe match <2mV, hfe match max 10% deviation).

For higher current rating:

BC807 and BC817.

For very good match i would choose SSM2212 and SSM2220.


ZTX types has low rbb which gives low noise, but stray capacitance is very high. They are best suited for MC preamps.

i hope it is usefull.
 
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#236
Alright, insulators placed. 18V across J7 and J8 set. Although, can't bias right. While turning R22, I get my 40W bulb tester going from very dim to bright lit. Soft start shuts the amp down at a point near 30 mV across R30. What's my problem?
 
#240
the more bias, the brighter the bulb will burn, is it drops a voltage relative to the current passing through it. The fact that you are able to adjust it would indicate that you have no shorts. I am not sure how your soft start works, but most of the time, they are simplky there to slow down a current rush at start up. Perhaps Sonny has more insight, but it seems like the dim bulb is unnecessary at this point. Where in the chain is the dim bulb tester? Before or after soft start?
 
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