Substituting Transistors & More..

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Hi! This is a post with several questions.

I'm working on an old plate amplifier, and have tested several transistors as open. What can I use to replace the following?

D1563A
B1086A

2SB688
2SD718

The D1563A/B1086A are driver transistors, and the output transistors are the D718 and B688.

Other transistors that are fine, but the corrosive glue used to hold the capacitors in place has turned their leads a blue-green color so I want to replace the following as well.

C1815
A1015
C2274

I can find a 2SC1815 from Central Semiconductor and a KSC1815YTA from On Semiconductor/Fairchild. Whats the KSC vs the more common 2SC? Same with the A1015. I can get a 512-KSA1015GRTA OR 512-KSA1015YTA What does the info on the end imply? The datasheet doesn't seem to be different between the two. Also, is there anything special with a JRC 4558 vs a regular 4558, or is JRC simply the manufacturer?

My other question(s)
Does anyone know how to build a subwoofer preamplifier? On the plate amp I'm repairing, it has a power amp board and a preamp board. The preamp has a phase switch, crossover, and volume. I know ebay has some cheap ones using 1 op amp. Does anyone have experience with those?

One last thing. I have a Hafler DH-101 that I use the boost line level signal, and also sometimes use the tone controls (Bass & Treble) I don't use this for phono, just my iPhone and computer. Rather than buy and restore another DH-101 for my other stereo, is there a simple preamp that does what I use my DH-101 for? I don't even use the input switches. I just have input jacks wired directly to the line level input on the main board.

Thanks guys!
 
JRC manufactured the 4558, which seems to be competent from other manufacturers. For line level 2x boost it is fine, but hisses a bit on any 50x input like magnetic phono.
Any old receiver at the charity resale shop for $10 would provide volume control and bass boost for a line level signal, but you'd have to replace a lot of electrolytic capacitors, clean the pots and switches, and delete the weak output section. I didn't like low power receivers and their accompaning bassless bookshelf speakers back when they were all the rage. Receivers did Simon & Garfunkel okay, but not symphonies or anything with bass.
 
Hi, Quinetnick

The power devices are from Thoshiba, but are discontinuated a few yars ago, maybe 30 years, at the time there are one good option to change the BD 711-BD712, DB 911-BD912, whit a more high voltage, and frequency cut, in all days, whit the same pakage Thoshiba have pairs for these aplicattion, i supose one of this news devices are 2SD1047 and respective pair.
Regards
 
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