$175 Class D amp--120 wpc

mboxler · « **Reply #3220 on:** 6 Apr 2012, 01:33 pm »

Good Catch! I only used the photos to get an idea of the wiring techniques...not the wiring itself! I wired mine according to the PCB...Left means Left... Also, I'm surprised the PS even powers up. Have you notified Tom of the Tranny to PS wiring "error". Or can if be wired either way???

I ignored the on/off switch on the PCB, and wired the case switch between the AC live on the IEC and the red wire on the tranny.

A dumb thought on the buzzing. I've spent enough time researching balanced vs unbalanced wiring in the last few days to make my head spin. As I understand it, in balanced mode, the input stage of the amp is going to calculate the difference between the two inverted signals from the + and - inputs to recreate the original signal from the preamp (which in turn eliminates noise picked up by the cable). Since you have no signal on the - input, and you have a full signal on the + wire, I wonder if this difference creates a buzzing sound. Would be interesting to borrow a balanced preamp just to test it out. I may remove my jumpers from pins 2 and 3, turn on my preamp, and see if I get a buzzing as well.

Best, Mike

mikeeastman · « **Reply #3221 on:** 6 Apr 2012, 02:46 pm »

I'm having a problem with my SDS 254, when I turn it on the left channel blue light only stays on for about 10-20 seconds then goes out. I tried disconnecting left side in to make sure problem wasn't with tube buffer no change, also disconnected resisters on gain, no change. Here are pics, only other thing I can think of is maybe jumpers for bridge, stereo are not connected right?

Anyone have any idea what problem is or any suggestion on figuring it out?

Thanks, Mike

mboxler · « **Reply #3222 on:** 6 Apr 2012, 04:55 pm »

Hey Mike...

Jumpers look good for non-bridged amp, unbalanced inputs. Interesting configuration of caps/resistors on your inputs!

Did you check the input voltage from the PS?

Mike

vinylb · « **Reply #3223 on:** 6 Apr 2012, 05:03 pm »

Quote from: mboxler on 6 Apr 2012, 01:33 pm

Good Catch! I only used the photos to get an idea of the wiring techniques...not the wiring itself! I wired mine according to the PCB...Left means Left... Also, I'm surprised the PS even powers up. Have you notified Tom of the Tranny to PS wiring "error". Or can if be wired either way???

I ignored the on/off switch on the PCB, and wired the case switch between the AC live on the IEC and the red wire on the tranny.

A dumb thought on the buzzing. I've spent enough time researching balanced vs unbalanced wiring in the last few days to make my head spin. As I understand it, in balanced mode, the input stage of the amp is going to calculate the difference between the two inverted signals from the + and - inputs to recreate the original signal from the preamp (which in turn eliminates noise picked up by the cable). Since you have no signal on the - input, and you have a full signal on the + wire, I wonder if this difference creates a buzzing sound. Would be interesting to borrow a balanced preamp just to test it out. I may remove my jumpers from pins 2 and 3, turn on my preamp, and see if I get a buzzing as well.

Best, Mike

Have not notified Tom yet, wanted to get others take on it, maybe I was just not looking at it properly. I also noticed in one picture he has the neutral/black wire going to live/red at the IEC connections.

I'll see what happens if I disconnect the rca cables and change the rca/balanced toggle.

krikor · « **Reply #3224 on:** 6 Apr 2012, 06:51 pm »

Vinylb...

Unplug the RCA connections so there is no input signal and then see if you get any buzzing. The toggle is not there to switch between the RCA and XLR inputs, but rather to select which type you have connected (in other words, you shouldn't be using both at once). The RCA is always connected to the amp input, so when you switch to XLR your amp is in essence only seeing one leg of a balanced signal which is probably what's causing the buzzing (at least in my neophyte guessing... you obviously don't have the other inverted leg since your are not running a balanced system).

As for the green and blue wires, I don't think it makes any difference which way they are connected to the PS since power is coming from a centertapped AC xfmer. You'll have like 40VAC on the L, 0VAC on the center tap (combined blue/green wires - these you want to make sure you get correct) and another 40VAC on N. The same is probably true for the IEC wiring... as long as the fuse and switch are on the live side, I don't think it matters which way the xfmer is connected.

Same holds true for the left/right amp inputs to back of panel. Doesn't really matter if you wire left to right and right to left as long as you make the same connections for the speaker jacks so that the correct orientation appears at the back of the amp (though that doesn't really matter either since you can always connect the left speaker to the right jack and vice versa). However, if you are talking about the polarity for each left/right connection (+ and GND) that is another matter and you'll want to get them correct.

On/Off switch on the amp board is optional and for putting the amp in standby mode, but leaves the power supply on. You need the switch between the IEC and transformer to completely turn off the amp.

krikor · « **Reply #3225 on:** 6 Apr 2012, 06:52 pm »

Quote from: mikeeastman on 6 Apr 2012, 02:46 pm

I'm having a problem with my SDS 254, when I turn it on the left channel blue light only stays on for about 10-20 seconds then goes out. I tried disconnecting left side in to make sure problem wasn't with tube buffer no change, also disconnected resisters on gain, no change. Here are pics, only other thing I can think of is maybe jumpers for bridge, stereo are not connected right?

Does the orange light come on after the blue light goes out? Sounds like it is going into some sort of protection mode. Could the speaker wires be shorted on the left channel?

mikeeastman · « **Reply #3226 on:** 6 Apr 2012, 08:33 pm »

The orange light comes on when amp powers up but not after blue light goes out. Voltage from power supply 93.5 volts. the caps and resisters are part of Dodd tube buffer out put. I disconnected left speaker outs no change.

TrungT · « **Reply #3227 on:** 6 Apr 2012, 08:45 pm »

^^^^^

Quote

SDS-254 - Required Power Supply: +/- 40 Volts DC to +/- 50 Volts DC Accepts Balanced or Single Ended inputs at up to 18 volts

mikeeastman · « **Reply #3228 on:** 6 Apr 2012, 09:25 pm »

So it sound like the problem is with power supply putting out to high of voltage. I have 14.6 volts going into power supply. Anything in pic of power supply that doesn't look right?

Æ · « **Reply #3229 on:** 6 Apr 2012, 09:34 pm »

While I'm really enjoying this thread, I'm appalled at the number of Do It Yourselfers here that haven't a clue as to what they are doing. Who seem to lack the basics, especially when understanding circuitry and diagnosing problems that they might encounter.

Letitroll98 · « **Reply #3230 on:** 6 Apr 2012, 10:01 pm »

Well, ya gotta start somewhere.

mboxler · « **Reply #3231 on:** 6 Apr 2012, 10:12 pm »

Wow...that took the Cheerful right out of the thread! Sorry you find me appalling (at least my wife has company!). I have learned a lot working with these kits, and realize I have a lot more to learn. I appreciate everyone's help, and hope to someday to be able to return the favor.

Mike...sorry, but I don't have that PS. Wish I could help!

Mike

Æ · « **Reply #3232 on:** 6 Apr 2012, 10:18 pm »

Quote from: Letitroll98 on 6 Apr 2012, 10:01 pm

Well, ya gotta start somewhere.

No problem if you are an experienced builder or have an electronics background, technical education.

Anyone not knowing what they are doing could end up with something useless, a total loss. Hopefully that doesn't happen.

Letitroll98 · « **Reply #3233 on:** 7 Apr 2012, 03:14 pm »

Quote from: Æ on 6 Apr 2012, 10:18 pm

No problem if you are an experienced builder or have an electronics background, technical education.

Anyone not knowing what they are doing could end up with something useless, a total loss. Hopefully that doesn't happen.

Well I mildly disagree on this. While I agree basic soldering skills, an idea of what a circuit looks like, and experience building a couple of project kits would be recommended, I don't think you need a technical education in electronics to tackle this project.

A big part of this thread is people with more experience and education, such as yourself, helping those with less skills. Helping. That would sorta be the word I would hope we focus on here. Denigrating. That would be the term we would want to avoid.

Just me helping people with less skills in those areas.

vinylb · « **Reply #3234 on:** 7 Apr 2012, 03:26 pm »

Sorry I am not at the level of most folks around here. I was under impression forums like this were setup to ahare information and also educate by sharing experiences

mboxler · « **Reply #3235 on:** 7 Apr 2012, 03:34 pm »

Quote from: vinylb on 7 Apr 2012, 03:26 pm

Sorry I am not at the level of most folks around here. I was under impression forums like this were setup to ahare information and also educate by sharing experiences

+1

roscoeiii · « **Reply #3236 on:** 7 Apr 2012, 05:48 pm »

+2, especially since these Class D amps are so well suited to DIY beginners.

wired4sound · « **Reply #3237 on:** 7 Apr 2012, 08:56 pm »

Just finished building my first DIY amp, courtesy of Class D (CDA 254L Kit). I do not have background in electronics and zero experience in soldering wire, but the project was a success! Thanks to the help of Tom's assistant, Roger.

I must say, the sound of CDA 254 is more detailed and has more punch on the bass than my Primaluna Prologue. I am very happy with the final result and it is now my main rig for 2-channel listening.

mboxler · « **Reply #3238 on:** 7 Apr 2012, 09:36 pm »

Congratulations

Did you use the Class D Audio case, or something else?

Mike

wired4sound · « **Reply #3239 on:** 7 Apr 2012, 10:28 pm »

Thanks. I built my own case, using MDF (17"x12"x4"). I am planning to add two more amp module for 6-channel. Each module will have separate toggle switch for flexibility. Once I completed the 6-channel, I can either use it for home theater or monoblock, or have separate speakers for each module.