$175 Class D amp--120 wpc

Flounder · « **Reply #2120 on:** 16 Oct 2010, 08:38 pm »

Wushuliu

The high eff DIY Fostex speakers are a flat 8 ohms or higher. VERY easy load and a sensitivity of 97.

None the less, the kit was sold as the answer to hard to drive speakers - maybe not as hard as the cremmies though. The Connex board will answer that when it shows. All I know is this amp won't be getting much, if anymore, money spent on it.

Bemopti123

Been down that road with Sim Audio and Pass - I preferred the sound of the SF tube amps.

I don't play loud ( give or take max of mid to high 70's) and with the speaker's sensitivity of circa 91, I'm using about a whole watt, the tube gear shows no shortage of current in this situation.I'd have expected the Class d to be the same.

I have an pair of very early Nuforce 8.02 amps and they did just fine for speaker control. I just didn't like the turn on /off nonsense and the clinical presentation the early ones were famous for

KB

toxteth ogrady · « **Reply #2121 on:** 16 Oct 2010, 08:50 pm »

I seem to recall someone considering a Paul Hynes power supply for their classdaudio amp. Does anyone know if anything became of that? I suspect Paul Hynes could sell a lot of power supplies if he had a customized module for the classdaudio amps.

Bemopti123 · « **Reply #2122 on:** 16 Oct 2010, 09:19 pm »

Quote from: Flounder on 16 Oct 2010, 08:38 pm

I preferred the sound of the SF tube amps.

KB

Although my current set up is in eternal flux, there is one thing to be said about those Sonic Frontiers Power 1, 2, 3 line of amps, while the bass was somewhat flabby in my own setup, perhaps an artifact of the speaker I was using then(Gershman X-1 monitors), the rest was divine. There has not been an amplifier that has given much such pleasure as the Power 2s. While I sold it back to someone in Canada, I still have fond memories of it. It was and still is an exquisite design. If and when I pare down my amp stable, which is quite ample, I might/WILL consider getting one of them again. What a bargain they are in today's $$$$.

Flounder · « **Reply #2123 on:** 16 Oct 2010, 10:37 pm »

Bemopti123

I've heard the Gershwins tend to have a slightly wooly bass so the combination of tubes and those could get a little out of hand but that midrange is worth it.

In many respects, I'm not at all unhappy. I was thinking about a major component change either speakers or amps. For the price of a tube swap I figured I'd try and see what class d had evolved into since the early Nuforce stuff.

In the course of my messing around trying to hit on something that would work with the SDS4, I tried a cable combination I hadn't done before. I had left that set up in when I went back to the tube gear and much to my surprise, it solved the couple little niggles I had. So ultimately, to get a combination that I'm happy with for under $500 is a huge bonus as the speaker range I was looking at was $5k plus. Even if the amp never gets plugged in again it was a cheap solution. However, it doesn't sound that bad, especially if the new power supply board does anything at all. I think it may turn into my summer amp when I don't listen too critically and the thought of turning on a whole pile of hot glass isn't too appealing.

Kevin

KB

Mariusz · « **Reply #2124 on:** 16 Oct 2010, 11:04 pm »

Please keep it on topic guys.

Feanor · « **Reply #2125 on:** 17 Oct 2010, 03:18 pm »

Quote from: Flounder on 15 Oct 2010, 08:23 pm

Hi Everyone

This is an update on the Class D SDS-4 amp saga in my system.

The ultra short answer is - it is out of the system.
...

The four main "issues" are:
...

4) This one should be no surprise. Tube amps simply have more "presence" and feel more like listening to a living performer/performance. The tube sound stage is bigger , deeper and more detailed.

I really hadn't thought about #4 until I put the tube gear back in and went "Oh ya that's what was missing" My sister was visiting and she heard the Class D. She commented it sounds nice but not as real as my tube amps she heard the previous visit. That's when I decided to pop the tube gear back in to see if she was right and she was.
...

Kevin

CDA's blurb says that their amps have a tube-like sound. Personally I don't agree with that. Anyway, tube sound is ultimately a preference. Whatever it is that tubes do, it's hard for solid state, whether class D, A/B, or even A, to duplicate it. My guess is that it is the largish amounts of low-order harmonic distortion that tubes produce that cause the euphonic effects associated with tubes, viz. "harmonic richness", "body", "depth", etc. The counter arguement is made that solid state, including class D, produce more higher-order and intermodular distortion. However, IMO, these arguements aren't balanced because while higher-order harmonic and IM distortion might be pyscho-acoustically more objectionable, overall distortion tends to be far lower in quality solid state gear. (Incidentally, I'm a tube user myself; I have and enjoy a Sonic Frontiers Line 1 preamp.)

So it come around whether quality s/s gear is more accurate. My guess is that it is and that, in a manner of speaking, tube enthusiasts really just "can't handle the truth". Anyway 90% of the equipment differences that I can hear are far outweighed by the differences inherent in the sound of the various recordings in my collection. And in my experience with the SDS-258, my best recordings sound better that ever with this amp.

Barry_NJ · « **Reply #2126 on:** 17 Oct 2010, 04:58 pm »

Has anyone compared the SDS-254 to the SDS-258? or a CDA to its SDS counterpart?

I know that I've read in this thread that Tom says the SDS board's sound is superior to its CDA counterpart, but I was wondering if any of the posters here have done some direct comparisons. I'm searching and reading, but it's a big/long thread

wushuliu · « **Reply #2127 on:** 17 Oct 2010, 05:12 pm »

Quote from: Barry_NJ on 17 Oct 2010, 04:58 pm

Has anyone compared the SDS-254 to the SDS-258? or a CDA to its SDS counterpart?

I know that I've read in this thread that Tom says the SDS board's sound is superior to its CDA counterpart, but I was wondering if any of the posters here have done some direct comparisons. I'm searching and reading, but it's a big/long thread

No. No direct comparison has been done. Although I think Nick77(?) has owned both and stated he preferred the SDS.

Barry_NJ · « **Reply #2128 on:** 17 Oct 2010, 05:24 pm »

Thanks, I was just reading Steve K's comparison of the SDS-258 to the Wyred4Sound STI-500 integrated.
I'll search for Nick77's posts.

mjosef · « **Reply #2129 on:** 17 Oct 2010, 06:15 pm »

I finish my initial build(regular cda) a couple nights ago, this is with a Connix(?) ps with beefed up caps, 40,000uF x 2...today I am comparing it to the Modwright KWA100 SE I have here on demo. Its not gettin' blown away is all I can say for now. More later.

Barry_NJ · « **Reply #2130 on:** 17 Oct 2010, 07:16 pm »

Quote from: mjosef on 17 Oct 2010, 06:15 pm

I finish my initial build(regular cda) a couple nights ago, this is with a Connix(?) ps with beefed up caps, 40,000uF x 2...today I am comparing it to the Modwright KWA100 SE I have here on demo. Its not gettin' blown away is all I can say for now. More later.

Martin, you gonna bring it to Mike's on Saturday? I'd love to give it a listen

P.S. I'm talking about your CDA Amp

mjosef · « **Reply #2131 on:** 17 Oct 2010, 07:41 pm »

Hey Barry, not sure I am making Mike's rave. But I am sure we can arrange a demo somewhere.
I do have to add additional heat-sinking to the stock slab, I have +/- 56.4V coming off the power supply which is still within the recommended +/- 8V @50V., but there is more heat generated of course.
My build incorporate a CLC filtering unit prior to the transformer, so its a little different than the norm. The sound is pretty warm compared to Deepak's build I had auditioned some months ago.
I am using a stock Harmon Kardon amp transformer which The PunkingMan was kind enough to strip and send the chassis. Have no idea on the specs of the transformer but the secondary had 40-0-40...this will be replaced with a massive 1kW. transformer I have in route...my destiny on this build is a stereo amp with two bridged cda 254 units to power my bass drivers.

DougSmith · « **Reply #2132 on:** 17 Oct 2010, 08:01 pm »

I built a dual SDS-254 amp (4 channels) a while back and have been happily using one of the two amps to power my pair of custom bandpass subs for the past 9 months or so. I was going to add a third sub for very low/infrasonic frequencies, but never got around to it because the first two work so well down to 20 Hz or so - which is just fine for most of what I listen to (music & movies). So, anyway - since one of the amps was going unused, I rewired them in bridged mode (500W) and then re-balanced the subs through my DCX. The drivers I am using are B&C 12TBX100s (rated at 1000W rms at 8 ohms). The overall timbre is similar, but the low end definitely sounds a bit clearer and more authoritative now as well. Just thought I'd relate that little bit of info. These really do make great sub amps... cool, quiet and powerful.

mjosef · « **Reply #2133 on:** 19 Oct 2010, 03:20 am »

Too much of a good thing...

Stock transformer:

Massive attack:

This arrived today; Will have to move the power supply to fit this big fella'

Update on the sound vs the Modwright KWA100 SE...in brief, not in the same league, falls short in just about every department. But it has potential...maybe with better coupling caps and power supply caps, better internal wiring (I used throw away IC wire for input leads, and regular 12ga. house wire for speaker wire and power supply).

Bemopti123 · « **Reply #2134 on:** 19 Oct 2010, 03:42 am »

That is a hunk of iron Mjosef. Gosh. Massive.

Has anyone have any good experience with the different wiring types to be used? Although I am familiar with hook up wires, what gauge should it be used, as well as the gauge/type of wire to be used from PS to board?

mjosef · « **Reply #2135 on:** 19 Oct 2010, 04:04 am »

Quote from: Bemopti123 on 19 Oct 2010, 03:42 am

That is a hunk of iron Mjosef. Gosh. Massive.

Yah...1,000 KVA.
I'm heading towards a bridged pair @ 500w. per channel...don't want the transformer to get in the way.

I have already swapped in double shielded coax wire(solid core) for the cheap stranded IC wire I had on the inputs. Haven't heard how it sounds yet...since I have to ship out the Modwright tomorrow, I want to get as much time as possible with it.
I will also experiment with 24ga. solid core silver wire on the inputs, and some other wire I already have on hand. More to come.

jtwrace · « **Reply #2136 on:** 19 Oct 2010, 11:47 am »

Holy Schnikes Batman!

wushuliu · « **Reply #2137 on:** 21 Oct 2010, 07:45 pm »

So I have two CDA amp boards - the 224 (120w) and 254 (250w). The 224 was requested with lower (26db) gain. I think the 254 was too, but I don't remember. The 224 was running with a linear power supply w/ 90kuf and a beefier toroid. The 254 is connected to a Connex SMPS500R SMPS. I've had the chance to compare the two somewhat and make some observations: first the 224 is louder than the 254. I am going to assume Tom did not reduce the gain after all, as the difference is by a wide margin. While swapping preamps as well as amp boards, I've found the 224 sounds a lot fuller and more dynamic. I'm guessing this also due to the gain and Aikido tube pre. I wonder if that's actually noise and distortion I'm hearing due to the increased gain. The 254 sounds leaner and possibly cleaner, but I need more listening time. I guess I'm just surprised a 6dB gain difference would be so pronounced (assuming that the stock are still at 32dB as mentioned near the beginning of the thread).

As for the SMPS500R, the jury is still out. I listened to it briefly a few weeks ago, and popped it back in yesterday. The first time around I just remembered thinking OMG where did all that bass come from. Like slamming bass. Real tight. Listening to it again last night and this morning, for sure the bass is strong in this one. I had to turn my sub way down. Beyond that I am not sure yet what to make of what I hear. My first thought is that there is actually less noise than w/ my linear. The music seems cleaner. But I am not sure how much of that is this gain issue or what have you w/ the 254. Definitely the music seems more 'controlled'. I think the audiphile term is 'attack' or whatever. I know the ideal thing to do would be to get an SMPS500R for the 224 as well to compare.

I guess I am just really surprised by the difference between the two. I just finished an Aikido preamp and w/ the 224 music was warm and fuzzy, but w/ the 254 it's leaner and clearer, and by a lot.

Edit: I cam across this post from on diyaudio from someone at Coldamp that sums up the SMPS500R in the low end: "About regulation: linear power supplies are almost never regulated, and this is specially true as power increases, due to efficiency and heat dissipaton issues. On the other hand, it is easy to make regulated SMPS, that will hold rails voltage up to full power with no problem. This translates in a deeper and more powerfull bass, mainly, although it has sonic impacts in the rest of the audio band."

Barry_NJ · « **Reply #2138 on:** 21 Oct 2010, 09:20 pm »

Interesting post wushuliu. I think the thing to do to really compare the boards would be to swap the amp boards in/out of the same chassis/power-supply. Did you solder the connections to the boards, or use the screw terminals? If the latter the swap would be pretty simple. Then you could compare, apples to apples, and oranges to oranges

Seeing how each board is effected by each power-supply. Your current comparison of different boards, with different power supplies, would for me, make it very difficult to determine what is causing what difference. It would also be important, IMHO, to get the gains matched between the boards.

wushuliu · « **Reply #2139 on:** 21 Oct 2010, 09:41 pm »

Quote from: Barry_NJ on 21 Oct 2010, 09:20 pm

Interesting post wushuliu. I think the thing to do to really compare the boards would be to swap the amp boards in/out of the same chassis/power-supply. Did you solder the connections to the boards, or use the screw terminals? If the latter the swap would be pretty simple. Then you could compare, apples to apples, and oranges to oranges Seeing how each board is effected by each power-supply. Your current comparison of different boards, with different power supplies, would for me, make it very difficult to determine what is causing what difference. It would also be important, IMHO, to get the gains matched between the boards.

Yeah, if I wanted track the cause down I would have to shell out more dough for the smps and then engage in back and forth shipping w/ Tom probably to have the gain matched (and unmatched again if I don't like it). So this is probably as far as I'll go. This is where having confirmed specs on these amps, like gain, impedance, etc. would be helpful.