Retro Amp 50W Single Supply

[Bilbon]

Thanks for the answer! R282 still has a value of 100k? I have a CC5551 Vceo 160V (CDIL) here...is it a better option than the BC337/16?

 

[wg_ski]

5551 has a lower power dissipation rating. You probably want higher than 0.8W, not less. You would have to measure actual collector current draw to be sure.

 

[indianajo]

Hi! In the previously mentioned CCE SA-130 amplifier, the power supply is 55 VDC. The circuit has a capacitance multiplier to power the preamplifier stage, which reduces the 55 VDC to 40 VDC. The AX6 that will replace the original amplifier will be powered with 67 VDC. Below is the original capacitance multiplier circuit. My question is what resistor values should I change so that with Vin of 67 VDC I have a Vout of 40 VDC?

Ax6 does not need a 40 v supply. The first stage 2n5401 (plastic TO92 case) runs fine at 69 v in my unit. Forget the bc337 and the cc5551 and omit the regulator in your sa-130. My unit does have a regulated supply, down from 73 v transformer rectifier output to 69 v. For 2 channels, 6.75 A output, I use 5 parallel tip147 driven by a 1.6 w 72 v zener diode stack. The darlington transistors are on a Pentium 2 heatsink. AX6 does not have the hum rejection of a constant current front stage with a lot of other transistors. Cuts wire count for point to point builds like mine.

 

[wg_ski]

The AX itself doesn’t, but The regulator/cap multiplier may be needed to feed another preamp board, if the AX’s are being used to replace power boards in an old integrated amp.

 

[Bilbon]

Yes, the capacitance multiplier is to supply the preamplifier with 40 VDC, which is why it is necessary in the circuit...

 

[Bilbon]

First tests... not good. When turning on the AX6, the 220R resistors of the drives start to smoke.... Any idea of the problem?

 

[avtech]

Is the pinout of drivers correct?

Some can be BCE, others ECB (for example).

 

[Bilbon]

Is there a possibility that the A1837/C4793 may have a different pinout than the standard?

 

[avtech]

They would normally be BCE, but you'd have to check the manufacturer's data sheet to confirm.

Where did the drivers and outputs come from? How reputable is the source? That is always something to consider.

 

[Bilbon]

The drivers and outputs were purchased at a local store here in Brazil. I'll check the manufacturers and pinouts. Thank you for your comment

 

[Bilbon]

I checked now...the pinout is ok...BCE. Who is the manufacturer of these transistors?

 

[Bilbon]

I just discovered the problem: human error and lack of attention 🙁 A long time ago I bought a batch of TIP35C, I didn't check it and kept it. Now that I went to see, there are some TIP36Cs mixed in, just two that I used on this channel and another that I used on the other channel Of course it would be a problem!!! PNP instead of NPN... As soon as I get it working I'll be back with news...hehe

 

[gannaji]

Use bulb tester next time !

 

[Mark Tillotson]

I've seen colour coded packages somewhere for PNP v. NPN, to help manufacturing get the right devices in the right places(!)

 

[wg_ski]

That was a Japanese transistor thing, and no longer in use. Never saw a green PNP TIP. And the last time they made 2SA1302’s (a long time ago) they were black instead of green. I do recall the green ones, though, from the early days, when you could get Real Toshiba from MCM. NEC’s were kind of a bluish green.

 

[Vrystaat]

I saw them today in a NAD 3020A 😉

 

[wg_ski]

It was probably manufactured in 1980. I have plenty of equipment with the green ones in them.

 

[Bilbon]

AX6 finally working! Good sound, no background noise... Bias 32mA, offset 33.4 (67VDC rail). Now it's time to assemble everything in the cabinet... Thank you to everyone who helped me!

 

[Bilbon]

Assembly finished! Now it's time to start with the final tests... AX6 giving new life to an old integrated amplifier 😀

 

[Bilbon]

Tests finished... everything works ok 🙂