$175 Class D amp--120 wpc

guest1632 · « **Reply #1480 on:** 24 May 2010, 11:22 am »

Quote from: matix on 21 May 2010, 08:07 am

Thanks to all who has helped, especially jtwrace, I have set up my SDS258. Very powerful bass indeed! As mentioned earlier, I am only capable of changing a light bulb before this project. So, hope that my success is an encouragement to all novices. While it may take an hour for the DIY enthusiasts here to assemble, it took me about four days to ask all the questions and buy the correct parts. But it can be done! Unfortunately, I am travelling tomorrow for 10 days and have to abandon it for 10 days!

Hi all,

I have a couple of ruler measurement questions for you.

How big is the SDS amps, with the RCA points at the rear and what is the diameter of the 400VA transformers? So Just trying to figure out the layout for less noise. I did see the SDS boards were about an inch longer, but what direction, hence the questions.

if I got a parmetal case, would the 12x12x3 be enough height? Thanks? Or would I be better to have an extra inch?

Ray

ichillpill · « **Reply #1481 on:** 25 May 2010, 01:00 am »

Can someone post a pic of an external power switch used with their class d amps ?. From my understanding the SPST switch connected to the power cord is used to shut off the power supply and having an external power switch installed on the amp board allows me to leave the power supply switch on and allows the amp to be on standby mode if no signal is received?

roymail · « **Reply #1482 on:** 27 May 2010, 07:34 pm »

Quote from: ichillpill on 25 May 2010, 01:00 am

Can someone post a pic of an external power switch used with their class d amps ?. From my understanding the SPST switch connected to the power cord is used to shut off the power supply and having an external power switch installed on the amp board allows me to leave the power supply switch on and allows the amp to be on standby mode if no signal is received?

The manual says to leave the amp board's "on-off" switch in the "on" position, then wire directly from the amp board to an external power switch. This proceedure does not involve putting a power switch into the AC line as shown in the manual's diagram.

So does that leave the transformer on all the time? Would it be better to wire an external power switch into the AC line instead of involving the "power on-off" on the amp board?

Answers, please ...?

steve k · « **Reply #1483 on:** 27 May 2010, 07:40 pm »

I believe the onboard switch only turns off power to the FETS. While the tranny would remain on in standby mode, there would be no power drawn from it since the FETS are off.
steve

roymail · « **Reply #1484 on:** 27 May 2010, 07:47 pm »

Thanks, Steve. Which of the two would be the preferred way to wire the power switch?

It's a bit confusing since the manual describes wiring from the amp board to an external switch. But the wiring diagram shows a power switch integrated into the AC line.

jtwrace · « **Reply #1485 on:** 27 May 2010, 07:49 pm »

I don't understand why you wouldn't want to wire the way the instructions are...this way there is no power to the tranny > power board > amp board.

roymail · « **Reply #1486 on:** 27 May 2010, 07:53 pm »

Quote from: jtwrace on 27 May 2010, 07:49 pm

I don't understand why you wouldn't want to wire the way the instructions are...this way there is no power to the tranny > power board > amp board.

This is probably the way most guys have routed AC to their amp, and the way I'll probably wire mine, too.

jtwrace · « **Reply #1487 on:** 27 May 2010, 08:00 pm »

IMO the less parts that have high voltage when not in use, the better.

steve k · « **Reply #1488 on:** 27 May 2010, 08:10 pm »

Quote

I don't understand why you wouldn't want to wire the way the instructions are...this way there is no power to the tranny > power board > amp board.

Interesting. I was under the impresssion it just shut the FETs off. Why does my heatsink still get warm in standby mode then? Just curious.
steve

wushuliu · « **Reply #1489 on:** 27 May 2010, 08:15 pm »

Quote from: steve k on 27 May 2010, 08:10 pm

Interesting. I was under the impresssion it just shut the FETs off. Why does my heatsink still get warm in standby mode then? Just curious.
steve

There are two sets of instructions now: the amp manual says to use the power switch on the amp board, but there is a separate diagram pdf on the site that says to switch from the tranny.

Mine is switched from the amp board because when I first got my amp there was no wiring diagram on the site, so I just followed the amp manual directions...

roymail · « **Reply #1490 on:** 27 May 2010, 08:21 pm »

Quote from: wushuliu on 27 May 2010, 08:15 pm

Mine is switched from the amp board because when I first got my amp there was no wiring diagram on the site, so I just followed the amp manual directions...

Both ways must be acceptable since they are both recommended. AC, by switching from the amp board does the heat sink remain warm as Steve mentioned? What about the transformer?

Nick77 · « **Reply #1491 on:** 27 May 2010, 08:31 pm »

Quote from: roymail on 27 May 2010, 08:21 pm

Both ways must be acceptable since they are both recommended. AC, by switching from the amp board does the heat sink remain warm as Steve mentioned? What about the transformer?

The heatsink and the transformer both remain warm to the touch, the transformer is barely warm though.

wushuliu · « **Reply #1492 on:** 27 May 2010, 08:33 pm »

Quote from: roymail on 27 May 2010, 08:21 pm

Both ways must be acceptable since they are both recommended. AC, by switching from the amp board does the heat sink remain warm as Steve mentioned? What about the transformer?

I think jtwrace is right about switching straight from the tranny as being the safest/best option. Maybe I'll do that when I put it in the new enclosure. The heatsink is not overly warm on standby, certainly nothing like when it's actually on. Transformer has never felt more than slightly warm to me, but I don't make a habit of playing w/ the amp while there's power running. Broke that rule once, 2 weeks ago, and we know how THAT turned out...

ichillpill · « **Reply #1493 on:** 27 May 2010, 08:45 pm »

The way I have setup everything is exactly as shown in this file

http://classdaudio.com/documents/transformer_115VAC_instructions.pdf

What I would like to do is to leave the AC switch on all the time so I don't have to keep turning it on.

My question is if I leave the small switch on the amp board on with the AC switch on, will this put the amp on standby mode if no signal is sent from the receiver/preamp?

jtwrace · « **Reply #1494 on:** 28 May 2010, 01:23 am »

Quote from: ichillpill on 27 May 2010, 08:45 pm

The way I have setup everything is exactly as shown in this file

http://classdaudio.com/documents/transformer_115VAC_instructions.pdf

What I would like to do is to leave the AC switch on all the time so I don't have to keep turning it on.

My question is if I leave the small switch on the amp board on with the AC switch on, will this put the amp on standby mode if no signal is sent from the receiver/preamp?

Yes, but you still have high voltage (120VAC) to the transformer which is outputing to the power board...

jacko2x · « **Reply #1495 on:** 28 May 2010, 05:55 pm »

Thank you Tom (to whom most of my questions went to) and to everyone for the very informative thread and for all the input and help that was provided here. Long story short, I bought the Class D amp (SDS-254) from Tom a month and a half ago, and designed and built a case around it. When I received the amp, I was able to run it on top of my little wodden table just for testing/burn-in purposes.
But last night, I completed my chassis and screwed everything in. I wanted to give this amp justice so I took my time building the chassis and voila. Forgive me for the not so encouraging photos, but I hope to take better shots when I get around to completing my light tent this weekend.

Unfinished Chassis:

Front Panel:

Rear Panel Unattached:

Laying out the components in the new chassis (Ready for marking drill holes):

Rear Panel Attached to Chassis:

SDS-254 boards and Toroid screwed into chassis:

All wired up and ready to go w/ top case Off:

Happy Holidays Everyone.

srb · « **Reply #1496 on:** 28 May 2010, 06:34 pm »

Quote from: jtwrace on 28 May 2010, 01:23 am

Yes, but you still have high voltage (120VAC) to the transformer which is outputing to the power board...

If in fact the amp board's on/off switch removes any load from the secondary side of the transformer, there shouldn't be any current flowing through the power supply board and only a small amount of no-load transformer primary current should be flowing, on the order of milliamps.

Does that sound more or less accurate?

Steve

Steidl Guitars · « **Reply #1497 on:** 28 May 2010, 06:38 pm »

Jacko2x, nice work!

Nick77 · « **Reply #1498 on:** 28 May 2010, 07:25 pm »

Nice work Jacko, love the mounted gain pots.

steve k · « **Reply #1499 on:** 29 May 2010, 12:38 am »

Beautiful! Simple, elegant, professional looking. Things have come a loooooonnnnnngg way in 1500 posts!!!! Most excellent.
steve k

$175 Class D amp--120 wpc

guest1632