My new SC480 Pair

Dilby© · 27th February 2006, 01:05 PM

Heres me first attempt at an amp..

2 SC480 modules
1 Speaker protector module
2 Power supply modules
1 300VA 30V Toroidal
In 19 inch rack case

50WRMS x 2 into 8ohm

Wiring needs to be tidied and thermal protection added, otherwise its finished..

To my ear sounds pretty good..

Dion.

Dazza · 4th March 2006, 08:50 AM

That's a nice looking unit you have there. I have to admit the rack cases look good as well, and they are easy to work with as most have aluminium front and rear panels.
Nice work, keep it up.

Cheers

Daz

ploveday · 5th March 2007, 12:03 AM

I see you've used a 30V transformer here, rather than the 28V specified.

I've been considering the same thing...

Have you had any issues with it, such as overheating etc?

Were any modifications required to make it work?

Thanks!

- Peter

Dilby© · 5th March 2007, 01:17 AM

Yes, thats right. I made no modifications. Originally I had 60 degree thermal switches on the heatsinks, it would turn off under heavy load. Upgraded to 90 degree switches and now gives no trouble at all. I notice one of the resistors on the board has discoloured a bit, but is no real cause for concern. Oneday I'd like to try a modified version with 21193/4 pairs in the output stage, upgraded drivers and front end with about 50v rails. I have enough 21193/4s to replace the 29/3055 devices, so I might do that oneday too.
Quoted from the SC website..
"The process basically involves increasing the main supply rails to ±50V, changing the output transistors to MJ15003/MJ15004 (TO-3 types), Q1-Q3 to BC556, Q4 & Q5 to BF469 and Q6 to BF470 and increasing the power supply capacitor values and voltage ratings to 63V. Naturally a much bigger transformer is also required."

I guess if you did use a 30v toroid and you had trouble, upgrading the devices would be the fix?

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4th March 2006, 08:50 AM	#2
Dazza diyAudio Member Join Date: Feb 2005 Location: Sydney	That's a nice looking unit you have there. I have to admit the rack cases look good as well, and they are easy to work with as most have aluminium front and rear panels. Nice work, keep it up. Cheers Daz

5th March 2007, 12:03 AM	#3
ploveday diyAudio Member Join Date: Jan 2006 Location: Adelaide	I see you've used a 30V transformer here, rather than the 28V specified. I've been considering the same thing... Have you had any issues with it, such as overheating etc? Were any modifications required to make it work? Thanks! - Peter

5th March 2007, 01:17 AM	#4
Dilby© diyAudio Member Join Date: Jan 2006 Location: Tasmania	Yes, thats right. I made no modifications. Originally I had 60 degree thermal switches on the heatsinks, it would turn off under heavy load. Upgraded to 90 degree switches and now gives no trouble at all. I notice one of the resistors on the board has discoloured a bit, but is no real cause for concern. Oneday I'd like to try a modified version with 21193/4 pairs in the output stage, upgraded drivers and front end with about 50v rails. I have enough 21193/4s to replace the 29/3055 devices, so I might do that oneday too. Quoted from the SC website.. "The process basically involves increasing the main supply rails to ±50V, changing the output transistors to MJ15003/MJ15004 (TO-3 types), Q1-Q3 to BC556, Q4 & Q5 to BF469 and Q6 to BF470 and increasing the power supply capacitor values and voltage ratings to 63V. Naturally a much bigger transformer is also required." I guess if you did use a 30v toroid and you had trouble, upgrading the devices would be the fix?

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