300+ wpc, brand new: $420

[Feanor]

I've just comlete my first semi-DIY amplifier. It's working great!

I was/am very a happy with my Monarch Audio SM-70 Pro monoblocks, but I undertook this build with a few objectives in mind:

1. I wanted a fairly simple, first audio project to amuse me in my recent retirement.
2. I wanted more in depth exposure to a digital amplier. I want a comparision no only with the high-bias, low feedback Monarchys, above, but also with the Bel Canto eVo2i, Tripath-based I owned a few years ago, (based on my memory 'cause the Bel is long gone).
3. See if substantially more power would make much of difference in my usage, say 2.5x the 120 wpc @ 4 ohms of the Monarchys.

What tempted me to this project specifically was the US-made, Class D Audio, (website here), amps. Their amps are based on commecially available "class D" chips, however the boards and circuitry are proprietary. I selected the SDS-258 (here) model, actually the kit that includes a linear power supply, transformer, and gain pots for US$360, (here).

The biggest challenge wasn't the electronics, which are basically plug-ang-play, but the cabinet construction. This was something new to me and I made a dozen mistakes along the way, but fortunately none were show-stoppers; (first time I've owned or used a "step drill"). Class D Audio can also supply a case, but it was a little rich for me at $190; my own case included some 1/2" MDF, 1x4" pine, and a Hammond aluminum case botton: this stuff cost me about $20. Assorted hardware including Neutrik XLR connectors rounded up the price to about $420 plus shipping.

The SDS-258, according to CDA, is ingeniously designed for balanced input and that's the way I built it since my preamp has balanced output. (Single-ended is also supported.)

My first impressions of the sound is very possitive -- more to follow. Here's a pic ...

[Geoffcin]

Sweet!!!

[audio amateur]

Nice! Are those new speak cables you have there? Look like Nordost

[kexodusc]

Well done, Feanor...and thanks for the link...I'm gonna have to try one of those soon...

[Feanor]

Nice! Are those new speak cables you have there? Look like Nordost

Yes, they're Nordost Flatline Gold. But they're not new, I've had them for years.

[luvtolisten]

Congratulations and nice job. Wiring looks professional, I can see it was well thought out.

[Feanor]

Congratulations and nice job. Wiring looks professional, I can see it was well thought out.

Thanks. I did try to keep the cable runs short over all, especially the source inputs and speaker outs. The wiring to the gain pots -- the black things at the back between the speaker outs and XLR ins -- comes with the kit; perhaps I ougth to have shortened them, but things seem fine at this point.

I'll comment on the sound in a day or two. So far it's really good.

[poppachubby]

Looks fantastic. But where do the tubes go?

[dakatabg]

Looks cool, I would love to hear how it sounds but I will never have the chance, Feanor, you gotta tell us

[thekid]

F
Congrats on completing a very cool project!!
Should'nt there be runes on the front or at least a Silmaril embedded on the front?

[Feanor]

F
Congrats on completing a very cool project!!
Should'nt there be runes on the front or at least a Silmaril embedded on the front?

I like that suggestion!

How about Feanor's device, (as designed by Tolkien)?

[Feanor]

Looks fantastic. But where do the tubes go?

Toobs, eh, Pops? Well there are none in sight nor any prospect of them with this amp.

I feel it's still early to give a definitive review -- for one thing, I'd like at least one swap back and forrth with my Monarchys. However I offer a few tentative remarks.

• Class D Audio says ... "Our Super D Series amps provide more life-like imaging and sound stage, along with the beautiful smooth tube-like sound we're known for. These amps are powerful, clean, quiet , and transparent." Mostly true.
• "Tube-like"? Well, there's a big variety of tube sound but I'd say not so much, especially if you mean "warm". There is some warmth in the 50-100 Hz bass region but the overall balance isn't especially warm. Vs. the Monarchys, there is some prominence at the top of the midrange, but then again the Monarchys are a little reticent in that area.
• "Smooth"? Yes! The device, at least to my old and feeble ears, is basically free of solid state "nasties": no grain, no etching, no glare, and more generally, no harshness. This I say with the reservation that the CDA won't likey gloss over the shortcomings of up or downstream equipment.
• "Powerful, clear, quiet"? Definitely.
• "Transparent"? Yes, big time! Excellent resolution and "air" far exceeding anything I've heard in the price range; (kicks the heck out of Adcoms and NADs I've heard). Furthermore, the equal of the Monarchys and perhaps even my earlier Bel Canto eVo2i.

In my system a noticeable quality is excellent brass and percussion sound from things like bells and cymbals, including cymbals struck with steel brush -- I believe the best I've heard in this particular regard (-- does that make it "tube-like"?). Bass generally seems a bit more powerful and punchy than the Monarchys (which aren't bad either). Is this the slight additional bass warmth? And/or is it the extra power??

[TheHills44060]

Wow that is so cool Feanor...great job!

Weird question but does that PS Audio power cable fit snugly in whatever IEC receptacle you used?

[Feanor]

Wow that is so cool Feanor...great job!

Weird question but does that PS Audio power cable fit snugly in whatever IEC receptacle you used?

Not so weird. It's bearly snug enough -- could be tighter or more positive. I don't like the excessive length of the PS Audio plugs either.

[GMichael]

Clean work Feanor. It looks great! Great review of how it sounds.

[theaudiohobby]

Feanor,

Congrats on completing your first DIY electronics project,

[E-Stat]

I've just comlete my first semi-DIY amplifier. It's working great!

Really cool. That brings back fond memories of building Dyna kits when I was a teenager. The attenuator box I use with the main system is also DIY using components from DACT, Cardas, JPS Labs and Par-Metal.

rw

[thekid]

I like that suggestion!

How about Feanor's device, (as designed by Tolkien)?

We are probably enter geek territory but I think that device would actually look really cool. If not that device then a silver tree on one end and a gold tree on the other with the green background would look nice on your little "jewel". You could probably find an overlay at a craft store that you could use.

[Feanor]

We are probably enter geek territory but I think that device would actually look really cool. If not that device then a silver tree on one end and a gold tree on the other with the green background would look nice on your little "jewel". You could probably find an overlay at a craft store that you could use.

By the way, the reason the exterior is green is that that was the only paint I had around and I was too cheap to go buy another color.

[bobsticks]

Feanor, as a person that has ruined highschool shop projects I gotta tell ya I respect what yer doin'...further you're bringing me back to remembrances of my Grandfather who, in later life, took up model ship-building as hobby. The intricate workings and the detail are all very impressive.

I hope that the project not only proves itself a worthy investment of time in compare and contrast but gives you a seperate and equal level of joy as those magniificent Monarchys that you have...

Peace, Cheers, and thanks for sharing...

M

[harley .guy07]

I love when a fellow audiophile puts their ability to work and even though its a kit this is an excellent example of the kind of things that can make this hobby fun. And I am glad it sounds good.

[Feanor]

Feanor, as a person that has ruined highschool shop projects I gotta tell ya I respect what yer doin'...further you're bringing me back to remembrances of my Grandfather who, in later life, took up model ship-building as hobby. The intricate workings and the detail are all very impressive.

I hope that the project not only proves itself a worthy investment of time in compare and contrast but gives you a seperate and equal level of joy as those magniificent Monarchys that you have...

Peace, Cheers, and thanks for sharing...

M

Thanks, 'Sticks!

[Geoffcin]

I love when a fellow audiophile puts their ability to work.

Say that twice!

Back in the 'day, kits were nothing to sneeze at. From DYNACO to HeathKit, guys like Feanor were making quality gear back when the average guy could only get his hands on great gear if they made it themselves or sold their blood for cash. That same homemade gear STILL commands big bucks, and rightly so!

[Feanor]

Folks,

I posted a complete review over at AA; here it is ...

http://www.audioasylum.com/forums/am...15/157758.html

[thekid]

Folks,

I posted a complete review over at AA; here it is ...

http://www.audioasylum.com/forums/am...15/157758.html

Good read!!