[vinylb]

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.

Congrats to you !!! Dig the custom enclosure and ample room for expansion

What speakers are you driving with 254L kit?

My

[vinylb]

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.

Krickor, thanks for your replies. I figured the L & N cables were ok to swap but center taps being critical. Switch supplied with the kit, I dont believe is rated for the use between IEC and transformer. In my 254L kit I did use a 120v rated switch. But I believe the switch Tom supplies can only be used for one purpose and that is to power on/off the amp board...but I could be wrong.

Also...thanks for correcting and enlightening me on the purpose of the toggle switch.

[mboxler]

Krickor, thanks for your replies. I figured the L & N cables were ok to swap but center taps being critical. Switch supplied with the kit, I dont believe is rated for the use between IEC and transformer. In my 254L kit I did use a 120v rated switch. But I believe the switch Tom supplies can only be used for one purpose and that is to power on/off the amp board...but I could be wrong.

Also...thanks for correcting and enlightening me on the purpose of the toggle switch.

FYI...I had the same question for Tom when I received the case.  His reply...

"As for the switch on the case… this is for the transformer AC so when you turn the amp on. The power supply and amp turn on. Just leave the switch on the amp turned on."

I can only assume it's rated appropriately.

Mike

[vinylb]

FYI...I had the same question for Tom when I received the case.  His reply...

"As for the switch on the case… this is for the transformer AC so when you turn the amp on. The power supply and amp turn on. Just leave the switch on the amp turned on."

I can only assume it's rated appropriately.

Mike

I stand corrected. Thx for info Mike

I have put my cover on and now enjoying my amp.
Sda-470 is perfect match for my maggies 1.6.
As much as I enjoyed my cda-254, 470 has a wider and deeper soundstage.
I also hear better seperation of instruments and continue to be amazed but how much more I am hearing.

[pix4work]

I just found this thread and haven't read every post yet. I've been looking for information on the SDA-470 amp kit. Is it a Class D Audio (brand) product? Maybe I'm not looking in the right place, or is this model a custom order? This model sure sounds interesting from the description, because if it will image well on Magneplanar speakers it should image well with other less demanding speakers, also. Thanks so much!

Pix4work

[firedog]

I just found this thread and haven't read every post yet. I've been looking for information on the SDA-470 amp kit. Is it a Class D Audio (brand) product? Maybe I'm not looking in the right place, or is this model a custom order? This model sure sounds interesting from the description, because if it will image well on Magneplanar speakers it should image well with other less demanding speakers, also. Thanks so much!

Pix4work

I assume the references are to the SDS 470; yes it is available, but only appears on the site as one of the options on the "build an SDS" page and as a complete build. It doesn't appear on the "kits" page or the "boards" page.

I actually wrote Tom yesterday about buying an SDS-470 board; he said he is finishing testing a new improved version of the board, and that it will be on the site soon. In any case, even if Tom doesn't update the site, write and ask about the board if you're interested. And yes, it sounds like a good match for Magneplanars, as it doubles power at 4 ohms, and almost doubles again at 2.

[firedog]

sorry, double post

[wired4sound]

Congrats to you !!! Dig the custom enclosure and ample room for expansion

What speakers are you driving with 254L kit?

My

I am currently using a modded AV123 X-LS mini-monitor, but it will be upgraded pretty soon, probably another GR-Research speaker. The amp is a perfect match for this modded X-LS speaker. The warm sound that I am used to (using Primaluna) is about 90% using CDA-254, but better bass and more detailed. I can never be happier.

[wgscott]

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.

This was the first and only DIY electronics project I have ever built.  It has been working fine for a year now. There actually isn't a whole lot to it.  You connect three boards together with a few wires.  It was a fun project.

I worry that in this country we have created such a fear of things like this, and school science labs, etc., that we have beaten the scientific and technical creativity out of the populace.

[Æ]

This was the first and only DIY electronics project I have ever built.  It has been working fine for a year now. There actually isn't a whole lot to it.  You connect three boards together with a few wires.  It was a fun project.

I worry that in this country we have created such a fear of things like this, and school science labs, etc., that we have beaten the scientific and technical creativity out of the populace.

I'm glad you got it right the first time, apparently not so for some of the others. Maybe what I should have said, is that it doesn't appear to be a kit for beginners. If you mess it up, then you end up with an expensive $175 loss.

[firedog]

In the old days, companies that sold kits sent detailed instructions with diagrams. Today they could easily send printed instructions with pictures and put a "how to" video on the web. Hard for me to believe that this wouldn't reduce the number of support emails Tom answered  and be very worth it for him.

Without that, first timers like me are afraid to build a kit.

[RichG]

Yes. by far the biggest failing of the ClassD stuff is the lack of documentation!  I'm absolutely amazed Tom doesn't get this sorted, he must spend hours on email with questions.

[matt_garman]

I agree, Tom could stand to beef up his documentation and info on the website.

But at the same time... if you take the time to read through this whole thread, you should clearly understand what needs to connect to what.  I did exactly that: read every page of this thread (over the course of many days), taking notes along the way.

And even if you don't want to take the time to read through the whole thread, you could "soft" hook-up everything (i.e. no solder), and before plugging it in, take pictures and post here.  If the pictures are good enough, I'd be really surprised if at least one person didn't come along and say yea or nay.  And if no one responds here, I'd be shocked if Tom himself wouldn't review your work.

If you don't have the patience to read through this thread and/or wait on responses to questions and pictures, then the DIY route probably isn't for you.  There's another side to the read-and-understand-before-building argument, and that is safety.  Those big capacitors on the power supply board store a lot of potential---life-threatening levels.

The power supply side of the build is where you face the biggest risk to your health; likewise, it is probably the side where the equipment risk is highest.  But it's probably also the simplest.  I distinctly remember many people, early in these threads, clarifying how the transformer leads connect to the power supply board.  I believe Tom now ships all transformers with the unused leads taped off.  So even if you're completely impatient and foolish, you have a 50/50 chance of hooking things up correctly.  Connecting the power supply board to the amp board is really trivial: + goes to +, - goes to -, and GND goes to GND.

Furthermore, you can easily check every stage of the power supply with a cheap (<$10) digital multi-meter (DMM).  I would argue that basic familiarity with a DMM is a hard prerequisite for building these kits.  At least understand how to check voltage and resistance.  Hook just the transformer up, plug it in, check the potential across the transformer leads.  Transformer output is documented.  Now connect the power supply.  Check voltage across the power supply outputs; this is also documented, but check with Tom to be absolutely certain.

(Just don't be sloppy with your DMM leads like me; that power supply is good for an electrical arc that will have you seeing white for a few minutes!  Now I use alligator clips. )

Also note that if you power up the power supply board before you're done working on the kit, you need to wait a while before working with it again.  Those capacitors store electricity even after the amp is unplugged.  I'm not sure how long you need to wait... probably 30 minutes (but again, this is something you can verify with your DMM).

The input/output side is more about common sense: turn your preamp all the way down on your first run; turn the gain all the way down (i.e. maximum resistance); don't use your nicest speakers initially; double- and triple-check all connections before plugging in; slowly increase volume/gain.

At any rate, Tom is now offering fully-built amps that are "plug and play".  Personally---and this is pure speculation on my part---I think the price will rise on at least the complete amps, if Tom manages to polish up his website and get his amps in the hands of some widely-read "pro" reviewers.

[steve k]

Very well said! 

steve k

[.Marcus.]

If i find some time and mod the couple C's i will try to find them also

Recently i had some time to change the couple C's and PS Caps of 2092 Input stage, please see picture bellow :

First i try the Nichicon KZ as couple C's (Elnas was on transit) :



Later on i receive the Elnas and replace the Nichicon KZ :



I like the sound of the Elna Silmic II more than KS (from first minute without burn in ) , KZ are more mellow, i decide to change the 220µF near the THAT1200 to Elna also :



Regards
Marcus

[wgscott]

I'm glad you got it right the first time, apparently not so for some of the others. Maybe what I should have said, is that it doesn't appear to be a kit for beginners. If you mess it up, then you end up with an expensive $175 loss.

It is far more simple than a beginners kit I purchased at the same time I ordered a soldering iron (wound up using my old one which I then found after 20 years rotting in a drawer).  I did wire the pots backward, had a ground wire come loose, etc.  Pretty much anything worth doing involves some degree of risk, but in this case the risk is small.  It is also quite possible for some to shock themselves severely, which if you want to wring your hands, seems more worthy of concern.

[wgscott]

ooops

[RichG]

Recently i had some time to change the couple C's and PS Caps of 2092 Input stage, please see picture bellow :

First i try the Nichicon KZ as couple C's (Elnas was on transit) :



Later on i receive the Elnas and replace the Nichicon KZ :



I like the sound of the Elna Silmic II more than KS (from first minute without burn in ) , KZ are more mellow, i decide to change the 220µF near the THAT1200 to Elna also :



Regards
Marcus

 

Looking good  Marcus   And how's the sound - much improvement?

[wushuliu]

Recently i had some time to change the couple C's and PS Caps of 2092 Input stage, please see picture bellow :

First i try the Nichicon KZ as couple C's (Elnas was on transit) :

Later on i receive the Elnas and replace the Nichicon KZ :

I like the sound of the Elna Silmic II more than KS (from first minute without burn in ) , KZ are more mellow, i decide to change the 220µF near the THAT1200 to Elna also :



Regards
Marcus

Hm, unless you are a solder pro (and maybe you are) I would not mess with those boards. The chips are sensitive and adding those caps may be doing more harm than good. Especially on the bottom of the board.

[.Marcus.]

 

Looking good  Marcus   And how's the sound - much improvement?

Thanks   
The system run around 2h and i really love it, normaly i'm to be reserved, but form me it is a clear improvement, don't expect such nice sound by change some components. The Elnas really match in my system. But i would say i have well improved and sensitiv system which surface every change.

Regards
Marcus