$175 Class D amp--120 wpc

wgscott · « **Reply #2500 on:** 22 Apr 2011, 06:57 pm »

I'm in. My SDS-254 kit is on the way, and I've ordered what I hope are all the needed ancillary parts from PartsExpress. I worry I am in over my head, but hope you will permit me to ask for advice when the time comes.

My aim is to use this with my Peachtree Nova, which I think might benefit from a bit more power in the amp department. If it sounds better, great. If for some reason it does not, I guess I can always hook up some outdoor speakers or something.

As for the chassis, I've gone back and forth on the various options. I'm now thinking if I can get a matching Nova outer chassis shell, it would look quite nice, and then get some custom front and back plates from Front Panel Express to try to match the style of the Nova. I know this isn't the cheapest option, but the potential for the coolness factor is worth a few more dollars. Maybe I could even put a little window in there, like the Nova has for the tube and blue LED, to peak in at the solid-state components...

Now, the wait. I feel like the little kid in The Christmas Story waiting for the decoder.

praedet · « **Reply #2501 on:** 22 Apr 2011, 10:36 pm »

My SDS-254 is playing

First, the system as it currently sits.
PC Engine Alix Linux based Music Server (Currently on a AC Wall Wart, but will be moved to Battery soon)
MF V-link USB-S/PDIF
Modified Lite Audio DAC
DODD Audio Battery Buffer (Running on the Battery Power Supply I created)
SDS-254 w/ DC Power Supply (Running on the Battery Power Supply I created)
Skiing Ninja Modded Polk LSi9s

Oh yeah, most importantly it is sitting in a temporary chassis provided by Trung!

How does it sound? I'll get to that. First the only small "huh?"

For now I have the pots in place and no mods to the amp. I am very suprised at how small the window is for the difference between little to no sound, relatively loud, and then cut-out of the amp. Right now the R and L are at about 475 ohms of resistance. Higher resistance than that means I turn the Buffer up a LOT higher. Thoughts?

The sound? Very, very nice. REALLY quiet. I mean literally there is NOTHING in the speakers when there is no music. Could be the Battery supply, the amp, or the buffer, but I like it! Very wide and deep sound stage and good dynamics. I haven't really turned it up yet as everyone is at home

Oh yeah, in the interim before this amp I was using the R and L of an Outlaw 7700.

Overall, I am very happy. This was made with stuff I had on hand due to the temporary chassis, so the components will be better when it is moved. Also, the speaker cable is crap

Pics? I'll get to those

praedet · « **Reply #2502 on:** 22 Apr 2011, 11:01 pm »

Sorry for the crappy cell phone pics...

TrungT · « **Reply #2503 on:** 22 Apr 2011, 11:54 pm »

^^^^^

I'm glad you have a good use for the bamboo chassis.

praedet · « **Reply #2504 on:** 23 Apr 2011, 02:24 am »

It wouldn't be running without it!

Any insight on the gain control? If I am measuring correctly it seems like I want about 250 ohms of resistance...

corndog71 · « **Reply #2505 on:** 23 Apr 2011, 04:57 am »

Another nice thing about those gain controls:

I'm using a tube preamp that uses a single tube per channel. It's hard to get matching tubes (3S4) without buying a lot of tubes. Also it has a single volume control. At the lower end of the volume pot the left channel cuts out before the right side.

The gain controls bring the music back into balance.

praedet · « **Reply #2506 on:** 23 Apr 2011, 11:57 am »

So, looking at the Amp board so that the left input is on the left, and the right on the right, the wires coming out of the board to the gain are red, white, black from left to right. If I now look at the gain pot with the connections going down, what color should go where? The directions referenced yellow instead of white, and the pictures a lot of folks have taken look like I wired different than others...

Ted

wgscott · « **Reply #2507 on:** 23 Apr 2011, 02:17 pm »

Quote from: praedet on 23 Apr 2011, 11:57 am

The directions referenced yellow instead of white

Really? There are directions? That would definitely help.

Apart from what is wired to the transformer, I think you supply the other wires, if I understand correctly.

corndog71 · « **Reply #2508 on:** 23 Apr 2011, 05:02 pm »

I went by this pic as a reference.

The wires supplied were so thin and fragile I had a hell of a time stripping them. I ended up yanking them out of the connector and replacing them with HGA wire I had on hand.

I wonder if the person who posted the first pic got it backwards though because turning the pots clockwise reduces the volume. It was such a pain rewiring those connectors I didn't feel like messing with them anymore. I guess it doesn't matter which way you need to turn them.

praedet · « **Reply #2509 on:** 23 Apr 2011, 06:45 pm »

^^^Thanks! Tom e-mailed me the following, apply it if you have the same color as me, or follow the picture above or the one after Tom's directions

"Thank you for pointing that out to me. I forget we just got in new wires and they’re different color than the last. Now, with the pot shaft facing toward you and the pins of the pot facing up, the black wire goes to the right pot pin, the white to the center pin, and the red to the left pin."

If you have little to no volume with an SDS, the pot is probably the problem...
Now I figure out what resistor is best for the Buffer!
I also thought I would post up a few better pics of the amp in Trung's bamboo box.

Here is the cord I just built for my Alix Music Server so that it runs on the same Battery supply as the Amp and buffer...

steve k · « **Reply #2510 on:** 23 Apr 2011, 07:16 pm »

Nice clean work!

praedet · « **Reply #2511 on:** 23 Apr 2011, 09:09 pm »

^^^Thanks!

This is the power supply...

steve k · « **Reply #2512 on:** 23 Apr 2011, 09:19 pm »

I'm amazed that after 15 months and 125 pages, this thread is still alive and kicking! It's a tribute to an affordable, quality product and a lot of ingenious work by DIY'rs. My hat's off to all of you.

steve

Nick77 · « **Reply #2513 on:** 23 Apr 2011, 09:27 pm »

Go Steve!! Hats off to the original thread starter, thanks again.

jtwrace · « **Reply #2514 on:** 23 Apr 2011, 09:31 pm »

Quote from: Nick77 on 23 Apr 2011, 09:27 pm

Go Steve!! Hats off to the original thread starter, thanks again.

corndog71 · « **Reply #2515 on:** 23 Apr 2011, 11:32 pm »

This is why pics are so important. I'll give it to Tom for putting out a great product but knock him back a few points for lack of proper installation pictures. I could create a proper instruction manual with nice, clear pics in a few hours.

And it looks like my gain control wiring is all wrong.

For those still unclear on the transformer wiring let's hope I got this right. It measured right and seems to work well so I think I got it right. Mind you I bought the tranny from Antek and not from Tom.

My taped CT leads.

avionic · « **Reply #2516 on:** 24 Apr 2011, 12:31 am »

Transformer wiring looks correct.

wgscott · « **Reply #2517 on:** 24 Apr 2011, 05:33 am »

I've got everything but the transformer now. Usually I avoid going to the mail box, because it is just filled with bills and death threats and biopsy results and letters from the IRS and that sort of thing. But now I actually look forward to the arrival of the transformer. Yet it eludes me. Such is my existential angst.

While I wait, I have been worrying about the connection between the amp board and the RCA jacks I plan to attach to the cabinet. Presumably EM interference is going to be worst inside the box. Does anyone use shielded wires between the RCA jacks and the amp board? Would it help?

corndog71 · « **Reply #2518 on:** 24 Apr 2011, 06:28 am »

If I remember correctly those toroidal transformers don't emit the same kind of em field as tradional transformers do. I doubt you'll need to resort to shielded wire. A simple twisted pair should be fine. I used a 3-wire braid partly because it allows me to double up on the signal wire and partly because I just like the way it looks. Plus my interconnects are the same 3 wire braid of HGA copper wire.

praedet · « **Reply #2519 on:** 24 Apr 2011, 11:32 am »

Speaker wire in the chassis, guage? Solid or Stranded? What about the power wire in the chassis. Same questions...