$175 Class D amp--120 wpc

wgscott · « **Reply #2540 on:** 26 Apr 2011, 04:54 pm »

Well, I haven't managed to get mine to work yet. I have the SDS 254 kit. I believe I have it wired correctly. The blue LEDs on the power supply come on, and when I flip the amp board power switch to "on", the yellow LEDs turn to blue. However, I get no sound. I can hear it turn on through the speakers, very faintly. Because I am impatient, while waiting for the proper connections to ship, I rigged up my iPod to test the signal. I can verify the iPod puts out sound via RCA inputs on my TV soundbar, so that much is working. I have RCA (unbalanced) female inputs to + and G on each channel, and verified that the contacts are good with a multimeter.

I haven't yet attached the gain control pots. Is the gain by any chance turned down or effectively off if I haven't connected those controls up?

corndog71 · « **Reply #2541 on:** 26 Apr 2011, 05:05 pm »

yeah, the incoming signal passes through those pots.

wgscott · « **Reply #2542 on:** 26 Apr 2011, 05:07 pm »

Good. I have to go to work to get some solder* (my British wife keeps busting my arse for how I mispronounce it).

* and to do some work.

Atlplasma · « **Reply #2543 on:** 26 Apr 2011, 05:21 pm »

Looking for some input on whether this is a good idea or not. I have an Outlaw 200 Monoblock that's developed a heat-related noise issue. It was a fairly inexpensive amp to start with, and I'm not sure it's worth sending out for repair.

The class D amp is interesting, and I was considering using the power section and case with one of the boards mentioned in this thread.

corndog71 · « **Reply #2544 on:** 26 Apr 2011, 05:36 pm »

Outlaw makes very good amps. I think it would be worthwhile getting it repaired.

srb · « **Reply #2545 on:** 26 Apr 2011, 05:43 pm »

Quote from: Atlplasma on 26 Apr 2011, 05:21 pm

I have an Outlaw 200 Monoblock .....

The class D amp is interesting, and I was considering using the power section and case with one of the boards mentioned in this thread.

It will depend on the DC output of the power supply. The Class D Audio amps will require

+/- 30VDC to +/- 40VDC (SDS-224)
+/- 32VDC to +/- 42VDC (CDA-224)
+/- 40VDC to +/- 50VDC (SDS-254)
+/- 42VDC to +/- 52VDC (CDA-254)
+/- 60VDC to +/- 70VDC (SDS-258)
+/- 62VDC to +/- 72VDC (CDA-258)

Then, the 1U case is 1-3/4"H, so I don't know if the amp boards will fit or not. A couple of the models specify 1.25" height, so they may all be that height. They also mention 9/16" standoffs, but I think you would need to use a shorter standoff closer to 1/4" or 3/8".

Steve

Atlplasma · « **Reply #2546 on:** 26 Apr 2011, 05:52 pm »

I was wondering about the power supply (among other issues). And you're right that the 1U enclosure is snug.

I'll do a bit more research and also see what a local shop would charge for a diagnostic. The fix might be fairly simple, and these amps are great for home theater front channels. (I have two more.)

Thanks for the quick and helpful feedback.

wgscott · « **Reply #2547 on:** 26 Apr 2011, 08:22 pm »

Still haven't managed to get it to work.

Doubtless I am doing something stupid. Is there any reason in principle an iPod touch won't work as a test source? I'm pretty much at a loss, apart from this, as to where to start trouble-shooting.

srb · « **Reply #2548 on:** 26 Apr 2011, 08:52 pm »

Quote from: wgscott on 26 Apr 2011, 08:22 pm

Still haven't managed to get it to work. Doubtless I am doing something stupid.

So this means you have either connected the gain control pots or installed fixed resistors in their place, and it still doesn't work?

Steve

wgscott · « **Reply #2549 on:** 26 Apr 2011, 08:56 pm »

Yeah, I found some solder and installed the gain control pots, fiddled with them, etc. I was kind of rushed since I had to go to work, so I easily could have overlooked something, but nothing obvious having just re-read the first 40 or so pages here during a boring meeting....

corndog71 · « **Reply #2550 on:** 27 Apr 2011, 12:53 am »

did you turn your ipod's volume all the way up?

Alternatively, you could get one of these

http://www.amazon.com/FiiO-L7-Line-Dock-Cable/dp/B004QVNS0S/ref=sr_1_16?s=electronics&ie=UTF8&qid=1303866087&sr=1-16

which bypasses the built-in volume and just passes a standard line level output. You would need a preamp which isn't necessarily a bad thing. It just takes you further down the rabbit hole.

wgscott · « **Reply #2551 on:** 27 Apr 2011, 01:13 am »

Works now. Naive Luser error.

The iPod using the mini-jack to RCA definitely gives a very weak signal. But I also found if I turned the gain all the way up (all the way counter-clockwise, counter-intuitively), it cuts out, but if I dial it back maybe a degree or two, it works. Is that normal, or have I fscked it up somehow?

I'm planning to use this with the pre-Amp stage of my Peachtree Nova, btw. The iPod was basically a test to make sure everything works and doesn't burn down my house or more importantly, destroy the pre-Amp and speakers.

wgscott · « **Reply #2552 on:** 27 Apr 2011, 01:26 am »

Ultimately, what I want to do is use the new Class D amp in this system. The Peachtree Nova has a pre-Amp (RCA) out, so I want to use this instead of its built-in Class A Amp. If this sounds significantly better, I may add a second amp board and do (passive) bi-amping.

I was able to buy an extra Nova case, so I can make something that matches for the Class D amp, and order customized front and back plates.

This is my first DYI audio project (in case it isn't obvious), so I am always in need of help in suggestions.

corndog71 · « **Reply #2553 on:** 27 Apr 2011, 01:30 am »

I haven't tried mine straight from the ipod. I would think you would get enough of a signal from it. I have my gain controls open all of the way as I prefer to get those cheap pots out of the way as much as possible. I have to remember to look for some higher quality ones like PEC.

As mentioned before a preamp is a good investment. If you can handle a soldering iron then I highly recommend Bottlehead's Quickie.

http://www.bottlehead.com/store.php?crn=220&rn=438&action=show_detail

Here's mine.

wgscott · « **Reply #2554 on:** 27 Apr 2011, 01:44 am »

Cool. If this one goes ok, then I'll try that for my next project. I only have one tube in the current pre-Amp.

The nice thing about the Nova is that if you want to use a different amp, there is a pre-Amp out, and if you want to use a separate amp and a separate pre-amp, there is a line-level out from the DAC.

praedet · « **Reply #2555 on:** 27 Apr 2011, 02:09 am »

Quote from: wgscott on 27 Apr 2011, 01:13 am

Works now. Naive Luser error.

The iPod using the mini-jack to RCA definitely gives a very weak signal. But I also found if I turned the gain all the way up (all the way counter-clockwise, counter-intuitively), it cuts out, but if I dial it back maybe a degree or two, it works. Is that normal, or have I fscked it up somehow?

I'm planning to use this with the pre-Amp stage of my Peachtree Nova, btw. The iPod was basically a test to make sure everything works and doesn't burn down my house or more importantly, destroy the pre-Amp and speakers.

I think you wired the gain pots wrong. That is what mine did when I had it messed up...

Check my picture up above. What color are the wires for your gain pot?

wgscott · « **Reply #2556 on:** 27 Apr 2011, 02:19 am »

Black in the middle, red on the right as the knob points away from you, white where the non-existent yellow wire is supposed to go.

I just found your picture:

That is TOTALLY different from what I have, and the instructions I got with the amp. WTF? I am surprised mine works at all.

praedet · « **Reply #2557 on:** 27 Apr 2011, 03:06 am »

Ignore the colors...

Point the pot with the "knob" towards you and the connections down. This next part is a little harder to understand, so bear with me and I might try to take a picture tomorrow. If you connect the platstic connector to the board and then look at the amp facing the inputs with the left input to the left and the right on the right. Now, disconnect that connector and spin it 180 degrees so that the part of the plastic connector that was away from you, is facing you. (The part that has the nub for the locking connector. Now, lay it down like that tieh the gain pot above it like I talked about and solder away.

To orient you with my connector, looking at the back of the amp my wires went red, white, black (1,2,3) from left to right. So with the pot facing towards you and down, the wires reverse and become black, white, red (3,2,1)...

Did this help or make it worse?

corndog71 · « **Reply #2558 on:** 27 Apr 2011, 03:37 am »

This is one instance where a picture truly is worth a thousand words.

wgscott · « **Reply #2559 on:** 27 Apr 2011, 04:22 am »