[Nick77]

    My amp is running pretty warm.  I wouldn't say hot.  I can hold my hand on the heat sink indefinitely BUT for being class D I was expecting it to run cool, or even ice cold.                                               

That would be normal. 

[TrungT]

Steven
Like Nick said, it's warm.
Nice wood working skill. 

[firedog]

mine isn't even warm.

[justinm]

wgscott, so you're saying it's okay to connect the purple wire to the top lug on my IEC connector? If so, that's what I'll do. 

So just a quick update, I pulled through last night and feverishly hooked everything up.  Got it fired up by early morning and will leave it on for about 150 hours of burn-in.  I have a serious concern. My amp is running pretty warm.  I wouldn't say hot.  I can hold my hand on the heat sink indefinitely BUT for being class D I was expecting it to run cool, or even ice cold.  Am I wrong in thinking this way?  Is everyone's amps running this warm?  My amp isn't even playing music and it's this warm.  Plus the top is off. 

If you guys would like to see photos of my build as well as other speakers I've built please see my image hosting website.  Szaiontz.imgur.com 

As for me, I'll solder up that purple wire here in a few.

Thanks!
Steven

My SDS-254 runs a little warm after playing loudly for a while and got pretty hot when pushed with 10" 4ohm subs (Dayton RS265hf). This is why Im getting the SDS-470 for subs and using 254 on mains. However its always cold with out a signal through it after it cools down for a few minutes. Its not in a box yet either just an mdf board with spikes.

[I.Greyhound Fan]

Does any one know the power specs for the SDS 258, 450 and 480 at 4 ohms?

I am thinking about getting one of these amps to replace my Parasound A21 which is 400wpc at 4 ohms.  I am wanting to stay in the same power range. My Magnepans really like the power and headroom of the A21.  I am not sure if it will be a step up or not.  I will pair it with my Van Alstine hybride preamp and hybrid DAC.  I would like to buy one of the new AVA FET Valve 400R and 600R amps but at $3K and $3.5k they are out of my price range right now with paying for college tuition for 2 kids.

[justinm]

Does any one know the power specs for the SDS 258, 450 and 480 at 4 ohms?

I am thinking about getting one of these amps to replace my Parasound A21 which is 400wpc at 4 ohms.  I am wanting to stay in the same power range. My Magnepans really like the power and headroom of the A21.  I am not sure if it will be a step up or not.  I will pair it with my Van Alstine hybride preamp and hybrid DAC.  I would like to buy one of the new AVA FET Valve 400R and 600R amps but at $3K and $3.5k they are out of my price range right now with paying for college tuition for 2 kids.

I think what you may want is the SDS-470. I just emailed Tom recently for specs on all these and the 470 seems to fit the high power low impedance requirements with 300 in 8ohms, 600 in 4, and 800 in 2. Ask Tom about how to order since the kit isnt listed right on the website yet. Hope this helps.

[I.Greyhound Fan]

I think what you may want is the SDS-470. I just emailed Tom recently for specs on all these and the 470 seems to fit the high power low impedance requirements with 300 in 8ohms, 600 in 4, and 800 in 2. Ask Tom about how to order since the kit isnt listed right on the website yet. Hope this helps.

Thanks!  It's just what I am looking for.  I wish Tom would update his site.  It looks like the 470 would be the one.  Plenty of power and judging by the specs you listed it looks like it would have plenty in reserve for dymanics.  I bet it sounds great at low volume levels too.

I got to do an in home audition and review of the new AVA 600r amp and that was the best sounding amp I have heard at low volumes.  It was very detailed.  Turning it up just made it better.

[krikor]

Thanks!  It's just what I am looking for.  I wish Tom would update his site.  It looks like the 470 would be the one.  Plenty of power and judging by the specs you listed it looks like it would have plenty in reserve for dymanics.  I bet it sounds great at low volume levels too.

At the risk of confounding matters for you, I recently contacted Tom about the same thing and ended up settling on a pair of the SDS-450 amps.  I think we are using the same speakers... Magnepan 1.6QR.  Initially I though I'd start with a single SDS-470 even though it seemed like overkill (though that's never really the case with Maggies).  But I wanted to keep the option open to go to a pair of amps for passive biamping or even mono blocks for more power.

Here's the response I got from Tom:  If you're going to run the amps in bridge mode, I would recommend the SDS-450 kits. They also run cooler and can put about 1000W RMS into your Magnepans.

The different models got so confusing with regards to power and price I put together a chart clarifying this for myself, based on what info I could dig up from Tom's site and this thread.  Here's what I came up with:

Model	SDS-224	SDS-254	SDS-258	SDS-450	SDS-470
Stereo watts
8 ohm	60	125	250	150	300
4 ohm	120	250	--	300	600
2 ohm	--	--	--	600	800
Mono watts
8 ohms	240	500	--	600*	800*
4 ohms	--	--	--	600*	800*
Board $	235	245	265	245**	265**
Kit $ w/xfmr	285	320	370	350	370

* Note from Tom: As far as power output in bridge mode the protection circuitry will prevent the amps from putting out more power than they actually could. The SDS-450 will put out about 600W into 8 ohm bridged and about the same into 4 ohm… protection circuit. The SDS-470 is just more power at about 800W bridged.

** Not currently listed on website, temporary price as of today 10/17/2011 possibly until this weekend. Will go up about $40 when listed on website. If anyone wants one before they are listed on the website, purchase the SDS-254 or SDS-258 and email Tom with instructions to upgrade to the SDS-450 (for SDS-254 price) or SDS-470 (for SDS-258 price).


The SDS-480 kit ($468) and SDS-1000 kit ($498) are simply the 224 and 254 kits with two amp boards and a single HD power supply, respectively.

I will send a copy of this to Tom to see if he can verify these numbers and fill in the holes.  I know it would make amp selection much easier if this was all available. Verified with notes added from Tom at Class D Audio

Oh, and I STILL have to assemble my amps and give them a try... maybe this weekend. 

[Barry_NJ]

Great chart kirkor! Thanks for that!

[justinm]

That is a real helpful chart, thanks. Whish Toms website had something like this. I have been bugging him a lot lately about specs and just ordered a SDS-470 for 2 subs. Now I wonder what 2 470's bridged would put out for $40.00 more than the 450's and when bridged how stable they would be at 2-4 ohms?

[krikor]

Got a quick response back from Tom and updated my previous post with the missing info for the SDS-450 and SDS-470.

If you are looking to buy just the 450 or 470 amp boards with a power supply, it looks like now would be good time to jump on them...

For right now (possibly until the weekend), I’m selling the SDS-450 for the same price as the SDS-254 and the SDS-470 for the same price as the SDS-258. When I have the time to get them listed on the website, the price of each will go up about $40.00. If anyone wants one before I list them on the website, they can purchase the SDS-254 or SDS-258 and email me to upgrade it to the SDS-450 (for SDS-254 price) or SDS-470 (for SDS-258 price).

[I.Greyhound Fan]

I just tried the CDA-254S in my reference system with my Magnepan 1.6's and Van Alstine hybrid preamp and DAC. Compared to my Parasound A21 amp the 254S lacked the deep bass, dynamics and treble resolution that the A21 has.  Bass was tighter and better controlled.  There 254 has a darker background, no grain and more air, transparency and wider sound stage.  But the midrange was thinner and it needed more slam and power.  I think that it may have better dynamics and bass with the 400va power transformer that the 254L has.

So now the question is, do I take a chance on an SDS-470?  How do the SDS amps compare to the CDA amps in sound, bass, treble ?

Thanks,

Larry

[TrungT]

^^^^^
I think NeilT had try the CDA-254 and he has the SDS-470 now.
You may drop him a note. 
To me big Transformer and PWR supply caps are important, more headroom and powerful bass.

[Barry_NJ]

Snip...

So now the question is, do I take a chance on an SDS-470?  How do the SDS amps compare to the CDA amps in sound, bass, treble ?

Thanks,

Larry

From my readings of this thread, for months now , the consensus seems to be that the SDS series is an improvement over the CDA series of boards.

[NeilT]

^^^^^
I think NeilT had try the CDA-254 and he has the SDS-470 now.
You may drop him a note. 
To me big Transformer and PWR supply caps are important, more headroom and powerful bass.

I tried the cds 254, thanks again Trung, and then bought the 470. It seems, from memory, that the 470 does everything a little better than the 254. I really liked the 254, but for the obvious reasons went with the 470, headroom, power, prebuilt, and only around 600 shipped.

The bass is amazing, especially at low level listening. I barely use my servo sub anymore.

I hope this helps.

Neil

[I.Greyhound Fan]

Thanks Neil!

[StevenZ]

I've got another dumb question.  Is it okay for the power supply section of my amp to stay on all the time?  For the last week all I've been doing is shutting down the amplifier board with my external switch (making the LED's yellow) while leaving the power supply board still powered up. 

Is this the way it was intended to operate or should I shut both of them down every time I am not using the amp? 

Thanks,
StevenZ

[mboxler]

Hi Guys...

My attempt to tri-amp my Klipschorns turned out to be very disappointing.  The midrange sound was hollow/muddy.  It has occurred to me that the BMS 4592ND-MID 16 ohm driver I'm using may be the problem.  Is it true that the SDS-224 amp can have problems driving speakers over 8 ohms?  If so, I may wire a 10 ohm resistor in parallel with the driver to bring the impedence down to around 6 ohms.  Any comments?

Thanks, Mike

[walkern]

I've got another dumb question.  Is it okay for the power supply section of my amp to stay on all the time?  For the last week all I've been doing is shutting down the amplifier board with my external switch (making the LED's yellow) while leaving the power supply board still powered up. 

Is this the way it was intended to operate or should I shut both of them down every time I am not using the amp? 

Thanks,
StevenZ

I leave my power supply on all the time, and only power up the active (output) section with the 'on/off' switch when I'm gonna listen, and I don't have any issues.  The amp stays a bit warm though, so make sure you've got proper ventilation.  Mine is an SDS amp.

Neil

[StevenZ]

Thanks for the reply. Good to know.  I keep the lid cracked on mine until I get a proper vent in there.