[dvenardos]

No, I don't have the SDS just commenting on the differences in sound between the Virtue units. I really like the tripath sound and curious how they would compare side to side.

Don

dvenardos: Do you have the SDS and the Virtue? which one do you like better?

[Feanor]

No, I don't have the SDS just commenting on the differences in sound between the Virtue units. I really like the tripath sound and curious how they would compare side to side.

Don

"Side by side"? No, but I did own a Bel Canto eVo2i which is Tripath-based.  That was a couple of years ago so I can't A-B the Bel with my SDS-258, but based on my recollection of the sound, I prefer the latter: less bright in the mid-range, solider low bass (40-100 Hz), more accurate instrument harmonics.

[hottuner]

I finished putting my SDS-4 kit into Jason's chassis this weekend. This is the "two ohm" version of the SDS board. Took a week longer than I'd hoped, but now I have an impression and a few photos.

first some background about my approach since I'm new here. I have a passel of amps. But I don't have a single "super amp" because I have two systems that are tri-amped, and I have found it's easier (and cheaper!) to "amp roll" instead of getting three great (and expensive!) amps to do the job. An example might be Adcom GFA-565 monos for bass, Adcom GFA-555II's for mid, and Monarchy SM70Pro for tweets.

Another wrinkle, I'm not home at the moment, I'm in Florida using a 6.5" 2-way with subs, and the amps I have on hand are the SM70Pro and Adcom GFA555II. The Adcom drives the monitors well at the crossover (85Hz) handing off bass to subs beautifully, and is dynamic and big sounding, but grainy. The SM70Pro sounds smoother and more musical, but no cojones   The SDS equals or betters the 555 in dynamics and bass, and betters the SM70 in soundstage and overall clarity. I think it might be the best sounding amplifier I own!

But the acid test for me will be using it with my Final Sound 1000i's. Can't tri-amp these babies, and I haven't had a good enough amp for them, so they have been mostly unused. I have heard them with a great amp, and know what they can do. So that's the test for the SDS-4, coming up hopefully in another few weeks (I wanted the 2 ohm version for the electrostatic impedance dip at high frequencies). I was going to run up to New Jersey for a few weeks this weekend, but hurricane Earl had other ideas.

A niggle, the power here is dirty and I have a slight 60Hz hum, low enough that music at low levels masks it. I have to get a cheap n cheerful power conditioner and have found some ideas here, interested in the Blue Circle Thingee so far, wondering what you guys think. I may go to shielded input cables too, can't hurt.

I'll see if I can post a pic of the board too, here goes

[Feanor]

...

first some background about my approach since I'm new here. I have a passel of amps. But I don't have a single "super amp" because I have two systems that are tri-amped, and I have found it's easier (and cheaper!) to "amp roll" instead of getting three great (and expensive!) amps to do the job. An example might be Adcom GFA-565 monos for bass, Adcom GFA-555II's for mid, and Monarchy SM70Pro for tweets.

Another wrinkle, I'm not home at the moment, I'm in Florida using a 6.5" 2-way with subs, and the amps I have on hand are the SM70Pro and Adcom GFA555II. The Adcom drives the monitors well at the crossover (85Hz) handing off bass to subs beautifully, and is dynamic and big sounding, but grainy. The SM70Pro sounds smoother and more musical, but no cojones   The SDS equals or betters the 555 in dynamics and bass, and betters the SM70 in soundstage and overall clarity. I think it might be the best sounding amplifier I own!
...

This is interesting because I currently own a pair of Monarchy SM-70 Pros and have, in the past, owned the Adcom GFA-555II.  I pretty much agree with your relative assessments except, perhaps, on one critical point.

IMO, neither the Monarchy nor the Adcom compare for resolution & transparency with the SDS.  The Monarchy is certainly a mellower sound that many people will prefer; it is maybe a little dark in the low treble.  I agree that the SDS has more bass power and is generally more realistic in the mid-low bass, say 40-100 Hz.  Most importantly, the SDS is a more accurate overall.  It more accurately conveys instrument harmonics through my Magneplanar MG 1.6s and produces their sounds more realistically, notably brass, percussion (e.g. cymbals), and strings.  The Monarchy is smoother, yes, but I would definitely not say more "musical" if we're talking about authentic reproduction of individual instruments.

The Adcom 555II is, IMO, a pleasant but rather dark sounding amp by comparison; it doesn't remotely approach the SDS for instrumental realism nor transparency.  The 555II has good dynamic bass punch, but the SDS is at least it's equal.

The amp I've owned that is closest to the SDS was the Bel Canto eVo2i which is a Tripath-based amp.  I dont' have the Bel around now but I think I'd give the nod to the SDS.

[hottuner]

I pretty much agree with your relative assessments except, perhaps, on one critical point.

The Monarchy is smoother, yes, but I would definitely not say more "musical" if we're talking about authentic reproduction of individual instruments.

We agree, the problem is I wasn't clear enough.    What I meant to say is the SM70 is more musical than the Adcom, but the SDS betters the SM70 for "soundstage and overall clarity" (ie musicality).

Anyway, still getting a fix on the SDS, but my early impression is that it does everything right. I just have to track down the source of the 60Hz. When I lift the ground and disconnect the input cables it gets pretty loud. Makes me wonder if I have mis-wired something.

[roymail]

I just have to track down the source of the 60Hz. When I lift the ground and disconnect the input cables it gets pretty loud. Makes me wonder if I have mis-wired something.

This is something that Wushuliu posted awhile back for noise suppression on a budget.  I'd recommend you contact him, or maybe he'll jump in here with some advice.

[wushuliu]

This is something that Wushuliu posted awhile back for noise suppression on a budget.  I'd recommend you contact him, or maybe he'll jump in here with some advice.

That's more of a conditioning device. Double checking the wiring is a good idea.

[hottuner]

Double checking the wiring is a good idea.

I measured the impedance across the signal inputs on the amp board, do these numbers sound right?
100 ohm across ground and minus, 22k ohm across ground and plus.

[raindance]

Many are using the Pass B1 buffer/pre which is zero gain, and I've have not read any complaints about needing more gain.  I'm sure others will jump in here to comment.

Are you aware that the gain can be increased on the CDA series amps from 26db (standard) to 32db (high gain).  That is twice the amount of gain increase you mentioned.  If you don't know already, email Tom to find out which gain setting your amp board has.

Let us know.

Explain how 26dB to 32dB (a 6dB change) is more than the gain of 3 I mentioned?

[Barry_NJ]

snip...

The only issue is that the class D amp really needs a gain stage rather than a unity gain buffer, so I'm looking for ideas for a great sounding tube circuit with a gain of 3.

...snip

Explain how 26dB to 32dB (a 6dB change) is more than the gain of 3 I mentioned?

Ummm... How are you measuring 'Gain'? Last I checked 6 is more than 3...

[srb]

Ummm... How are you measuring 'Gain'? Last I checked 6 is more than 3...

A 6dB gain is equal to a power ratio of 4X.  A 4X power ratio is still more gain than 3X, if that is what is being referred to.
 
Steve

[raindance]

We are talking voltage gain not power. A voltage gain of 3 is 9.5dB.

[hottuner]

Well since hurricane Earl was down to a cat 2 Friday morning I drove to NJ this weekend after all. Of course I was anxious to hear the new amp on the Final Sound 1000i stats, and the first impression is (drum roll please) - the amp is superb with them, the stats are really on song. I don't have a lot of experience yet with the Finals, but I have never managed to get great sound with them at my house. I knew the problem was I did not have a good enough amp because I schlepped them over to a buddy's house who has an amazing Quad 57 set-up, and the Finals sounded wonderful at the end of his chain. Well now they are sounding wonderful at my house too and doing that thing stats do when all it right with set-up, that soft enveloping sound but with amazing levels of detail and staging precision. Dynamics are also very real sounding with excellent bass extension (for stats) but I haven't pushed too hard, going to take some time to find the edges of the envelope, and play with subs too. They are in a smallish extra bedroom at the moment, and good levels are easy to achieve. In this room I wouldn't really need a sub, they get loud enough running full range. I can't say if the Final's sound as good as they did at my buddy's place, it was a very different room for one thing, but I would say "same ball park", except for price of amplification of course!

Yeah, I'm a happy camper right now 

Still have that pesky low level 60 Hz hum, but I have some ideas to try out that I think will work.

Speaking of pre-amps, of the ones I have on hand at the moment the Van Alstine Insight is the best lock. I have never heard this pre sound this good either, I guess I didn't know how good it was!

And speaking of subs I will put my two bits in and say check out Epik Empires, a true cheap n cheerful bargain if there ever was one. I've had a lot of subs, a pair of these are easily the best.

Did I say I was a happy camper right now? 

[jtwrace]

Show us some pics of that Class D.

[hottuner]

Show us some pics of that Class D.

Hey Jason,
they are in my gallery.

[jtwrace]

Hey Jason,
they are in my gallery.

Nice job and nice case.   

[Barry_NJ]

I finished putting my SDS-4 kit into Jason's chassis this weekend. This is the "two ohm" version of the SDS board. Took a week longer than I'd hoped, but now I have an impression and a few photos.

... snip...


I'll see if I can post a pic of the board too, here goes

Odd, I couldn't find a SDS-4 amp board on the Class-D Audio web site 
I even just looked for a board with 6 out-put devices and didn't see one.
Could you give us a hint as to some of its specs?

[hottuner]

Nice job and nice case.   

The case is gorgeous, I love it! Thank you for making it. I'm thinking I may get another amp in case I want to bi-amp something. Better do it before you run out of cases!!!

[jtwrace]

The case is gorgeous, I love it! Thank you for making it. I'm thinking I may get another amp in case I want to bi-amp something. Better do it before you run out of cases!!!

Now is the time iwth the case sale!!!

[hottuner]

Odd, I couldn't find a SDS-4 amp board on the Class-D Audio web site 
I even just looked for a board with 6 out-put devices and didn't see one.
Could you give us a hint as to some of its specs?

It's the 2 ohm version, and stable with 1 ohm also if I'm not mistaken. I specifically asked Tom about it since stats typically dip to 1 ohm at high frequencies. On the other hand there is very little energy at those frequencies, so it not so much a question of enough power as stability.

Other than that I don't know too much about it, for example one thing I am curious about is whether all the SDS variations would sound the same on an easy load (all loafing). Tom also said certain parts for the SDS-4 are in tight supply, which may be why it's not on the site.