$175 Class D amp--120 wpc

roymail · « **Reply #2840 on:** 20 Oct 2011, 06:35 pm »

StevenZ, did you get your amp going? What pre are you running in front of it? And, what speakers?

I've read plenty good things about the SDS amps series when properly implemented. Curious to hear your impressions.

srb · « **Reply #2841 on:** 20 Oct 2011, 06:42 pm »

Quote from: mboxler on 20 Oct 2011, 02:56 pm

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?

Don't know if the SDS-224 has any problems driving 16 ohm loads, but if you put a resistor in parallel with the driver, the resistor would have to be a very large one with a power rating sufficient to dissipate the wattage. You would be dissipating more power in the resistor than the speaker driver, and in the resistor's case it would be 100% as heat.

Steve

mboxler · « **Reply #2842 on:** 20 Oct 2011, 07:20 pm »

Quote from: srb on 20 Oct 2011, 06:42 pm

Don't know if the SDS-224 has any problems driving 16 ohm loads, but if you put a resistor in parallel with the driver, the resistor would have to be a very large one with a power rating sufficient to dissipate the wattage. You would be dissipating more power in the resistor than the speaker driver, and in the resistor's case it would be 100% as heat.

Steve

Thanks, Steve

The crossover currently installed (ALK Engineering) sounds really good with the amp, considering that it has to balance three drivers of varying impedance and sensitivity. The midrange is attenuated with an autotransformer, which also multiplies the 16 ohm driver impedance. A 10 watt/10 ohm "swamp resistor" in parallel brings down the impedance to approx 8 ohms. I just wondered if this was the issue.

Again, thanks for the reply.

Mike

StevenZ · « **Reply #2843 on:** 21 Oct 2011, 01:36 am »

Hey guys I'm currently running an Audio-GD NFB12 DAC/Preamp with my SDS-224. They're powering a set of Mark Audio Alpair 7 Gen 3 drivers. My other set is a pair of 15" Hawthorne Audio Silver Iris coaxial drivers mounted open baffle. The amp/speaker/pre sounds fantastic. I honestly couldn't be more happy with the combination. Powerful preamp, powerful amp, and truly wonderful driver.

The Mark Audio full range drivers are amongst the finest I've ever heard. If anyone is considering building a set of full range speakers. Put these at the top of your list. They won't disappoint.

Cheers,
Steven

rvsixer · « **Reply #2844 on:** 21 Oct 2011, 05:29 am »

Quote from: StevenZ on 21 Oct 2011, 01:36 am

Hey guys I'm currently running an Audio-GD NFB12 DAC/Preamp with my SDS-224...The Mark Audio full range drivers are amongst the finest I've ever heard. If anyone is considering building a set of full range speakers. Put these at the top of your list. They won't disappoint.

Hmmm.

I have a CDA-224 amp kit, and two EL70 (made by Mark Audio customized for CSS) 4" full range drivers just finishing break-in. I wonder what I should do with them

.

Seriously, thanks for the vote of confidence on the MA drivers sounding good with classD amps. I was waiting on a tube kit, but the vendor did not deliver. After that experience, more research and this thread led me to ordering the classD.

roymail · « **Reply #2845 on:** 21 Oct 2011, 03:38 pm »

Quote from: StevenZ on 21 Oct 2011, 01:36 am

Hey guys I'm currently running an Audio-GD NFB12 DAC/Preamp with my SDS-224. They're powering a set of Mark Audio Alpair 7 Gen 3 drivers. My other set is a pair of 15" Hawthorne Audio Silver Iris coaxial drivers mounted open baffle. The amp/speaker/pre sounds fantastic. I honestly couldn't be more happy with the combination. Powerful preamp, powerful amp, and truly wonderful driver.

Thanks for posting your impressions of the Class D amp along with your other gear. Glad you heard things are sounding good at your house.

StevenZ · « **Reply #2846 on:** 21 Oct 2011, 04:00 pm »

Absolutely. I couldn't be more thrilled at the way this amplifier sounds and how well it works with the Audio-GD NFB12 DAC/Pre. I fully believe that the Class D Audio amps need an active line stage to achieve their highest potential.

I'm now a huge supporter of Tom's amplifiers and will spread the word with whomever may be interested in building one. My only complaint is Tom's lack of customer service and the much needed updates on his website. A nicely put together manual would have been appreciated with the kit as well. With those things aside, I feel that his amps offer a great solution for those who crave a DIY build and demand a high performing, tonally accurate 2 channel listening experience.

Cheers to you guys who pick up where Tom leaves off.

-StevenZ

StevenZ · « **Reply #2847 on:** 21 Oct 2011, 04:13 pm »

Quote from: rvsixer on 21 Oct 2011, 05:29 am

Hmmm.

I have a CDA-224 amp kit, and two EL70 (made by Mark Audio customized for CSS) 4" full range drivers just finishing break-in. I wonder what I should do with them .

Seriously, thanks for the vote of confidence on the MA drivers sounding good with classD amps. I was waiting on a tube kit, but the vendor did not deliver. After that experience, more research and this thread led me to ordering the classD.

I'm glad you're supporting Mark Audio drivers. I've got a couple builds under my belt using his drivers and each one of them has been a complete success. The provided "Pensil" cabinet plans are easy enough for anyone with minimal build experience to complete and will offer the best possible results.

Though they get docked a couple points for their lower sensitivity (when compared to other FR drivers), they gain them all back by actually having usable suspension travel for a lush bass response.

If you need any pointers or advice for speaker building feel free to PM me and I'll help where I can.

matt_garman · « **Reply #2848 on:** 21 Oct 2011, 05:58 pm »

What do you guys think would be an appropriate switch mode power supply (SMPS) for the SDS-470 in bridged mode? Perhaps something like this A1000SMPS from Connexelectronic? I'm thinking about building a pair of 800 Watt (at 4 Ohms) monoblocks with the SDS-470 board. I'd like to use a SMPS to reduce size and weight. Plus, I seem to recall at least one person reported success using Connexelectronic switch mode power supplies earlier in this thread.

roymail · « **Reply #2849 on:** 21 Oct 2011, 08:34 pm »

Hey Matt, send a PM to Wushuliu (Ainsley) or poseidonsvoice (Anand.) I'm certain that either of them can answer your questions about the SMPS. Or, maybe they will answer in a post. Just two of many here on AC that have the experience and knowledge to help you.

HT cOz · « **Reply #2850 on:** 21 Oct 2011, 10:31 pm »

I'm pretty sure you could ask Christi of Connex too.

That sounds like a bad a__ project. Be sure to post pictures.

walkern · « **Reply #2851 on:** 21 Oct 2011, 10:53 pm »

I am using a Connex 500 SMPS with one of the smaller SDS amps, and it works beautifully. it is light weight, a no-brainer to hook up, and sounds no different to me than the linear supply that I originally had with my amp (and sold to a work colleague). It is quiet (no hum, buzz, etc) and doesn't seem to radiate any untoward noise even though it is placed immediately next to the amp board in the chassis. The only down side to using the Connex supplies is the wait to get one (mine took about 30 days from order to delivery here in the USA). Seems to me that the A1000 would be a perfect match for the SDS 470.

Neil

I.Greyhound Fan · « **Reply #2852 on:** 22 Oct 2011, 07:04 pm »

I am curious and want to know, how many people have have had amps that cost over $2200 and have replaced them with these SDS-amps? And what amps did they replace?
What do they like about the SDS-amps better than the amp that they replaced.

matt_garman · « **Reply #2853 on:** 22 Oct 2011, 10:35 pm »

Quote from: walkern on 21 Oct 2011, 10:53 pm

I am using a Connex 500 SMPS with one of the smaller SDS amps, and it works beautifully. it is light weight, a no-brainer to hook up, and sounds no different to me than the linear supply that I originally had with my amp (and sold to a work colleague). It is quiet (no hum, buzz, etc) and doesn't seem to radiate any untoward noise even though it is placed immediately next to the amp board in the chassis. The only down side to using the Connex supplies is the wait to get one (mine took about 30 days from order to delivery here in the USA). Seems to me that the A1000 would be a perfect match for the SDS 470.

Awesome! Did you happen to measure power consumption with the SMPS?

Switch-mode power supplies are supposed to be more efficient, right? That is one of my big goals with giving these amps a try: getting speaker power on par with my QSC, but with lower AC power.

Nick77 · « **Reply #2854 on:** 22 Oct 2011, 10:49 pm »

Quote from: matt_garman on 21 Oct 2011, 05:58 pm

What do you guys think would be an appropriate switch mode power supply (SMPS) for the SDS-470 in bridged mode? Perhaps something like this A1000SMPS from Connexelectronic? I'm thinking about building a pair of 800 Watt (at 4 Ohms) monoblocks with the SDS-470 board. I'd like to use a SMPS to reduce size and weight. Plus, I seem to recall at least one person reported success using Connexelectronic switch mode power supplies earlier in this thread.

To be honest out of 143 pages only several people have imployed the smps.

Adhara · « **Reply #2855 on:** 23 Oct 2011, 06:02 pm »

Hi,

I'd like to get your feedback about classdaudio power amps.
Did someone has compared to Wyred power amps (B&O modules) ?

I'm looking for the MC model here http://classdaudio.com/products/complete-amplifiers-1/complete-6-channel-amp.html
I've sent an email to Tom and waiting for him to answer my questions.

Are SDS-258 best modules from the brand ? I need it to manage both 4 Ohm and 8 Ohm speakers.
Not sure this module can deal with 4 Ohm impedance.

Do you know if we can adjust the gain with a dial (for each chanel outptut) ?

Regards.

rvsixer · « **Reply #2856 on:** 23 Oct 2011, 09:33 pm »

Quote from: Adhara on 23 Oct 2011, 06:02 pm

Are SDS-258...I need it to manage both 4 Ohm and 8 Ohm speakers.
Not sure this module can deal with 4 Ohm impedance.

Do you know if we can adjust the gain with a dial (for each chanel outptut) ?

http://classdaudio.com/sds-258.html

walkern · « **Reply #2857 on:** 24 Oct 2011, 12:24 pm »

Quote from: matt_garman on 22 Oct 2011, 10:35 pm

Awesome! Did you happen to measure power consumption with the SMPS?

Switch-mode power supplies are supposed to be more efficient, right? That is one of my big goals with giving these amps a try: getting speaker power on par with my QSC, but with lower AC power.

I did not measure the power consumption of the SMPS. I checked the output voltage and adjusted it down just a wee bit, but never checked to see how much power it draws. Part of why I switched to an SMPS was to take advantage of the efficiency of both it and the Class D amp module... and I am just assuming Christi has been accurate and truthful about the efficiency of the SMPS.

Neil

matt_garman · « **Reply #2858 on:** 26 Oct 2011, 02:23 pm »

I finally completed my SDS-470 kit build this past weekend. I thought I'd post my initial impressions.

First: on the first test, I powered it on, but got no sound. I noticed the on-board LEDs indicated "Left Off" and "Right Off". The power supply lights were on. I used my DMM, and verified that I had DC going to the amp board. Nothing changed on the preamp side, and the music was playing. I was about to come here to ask for help when I noticed the little built-in "on/off" switch on the side/bottom of the amp board! I switched it on, and I got music! Classic ID-10-T error on my part.

Anyway: config is as follows: FLAC files (from CD rips) on computer, optically connected to Emotiva XDA-1 preamp/DAC, to power amp via XLR, to Salk Songtower speakers. Original power amp was a QSC RMX2450 "pro" amp; new amp is obviously the SDS-470 kit.

This are my initial impressions only, since I've only been able to listen to music for 20--30 minutes at a time over the last few days. So far, it seems to me about the same as the QSC. And that's not a bad thing! I was completely happy with the sound quality of the QSC. My goals for the SDS470 were (1) lower power consumption; (2) same (or improved) sound quality; and (3) have fun. Going by those three criteria, this was a complete success.

On the power consumption front, I'm using an AC Watt meter (Kill-A-Watt). The SDS470 seems to pull about 22 Watts, both at idle (no music) and typical listening levels. I haven't really cranked it up yet. Compared to the QSC, which pulled 40--60 Watts between idle and music. A definite improvement in power usage. As I suggested above, I'd like to get a switch-mode power supply (SMPS) to see if I can further reduce idle power consumption.

Regarding the "have fun" thing: I definitely enjoyed the electronics aspect of this. But I didn't particularly enjoy working on the case. I bought an aluminum Par-Metal case on Ebay. If I go forward with the dual bridged sds470 monoblock project, I think I'll just bite the bullet and pay for professionally machined and finished enclosures. I even went bare-minimum on my design: combined fuse+IEC, no power switch, two XLR inputs and four speaker binding posts. For a future build, I'd like to have two switches (mains power and amp board power), separate IEC and fuse holder, plus all kinds of LEDs. I just don't have the patience for all that drilling and cleanup.

Anyway, as for the sound quality discussion (what everyone is probably most interested in). On the very first listen, as I mentioned briefly above, I really couldn't tell much difference between the SDS470 and the RMX2450. On a few rare occasions, I thought I've heard a little bit of sibilance... but lately, I haven't heard that. Not sure if I imagined it or not. Also: depending on the input gain setting of the pots, I can hear a very faint hiss coming from the speakers when my ears are a few inches away or less (and there is no music playing). Adjusting the gain fixes this though.

I don't know if my ears are getting used to the unit, or it's being "broken in" (a concept I'm not sure I really believe in anyway), but last night I felt like the amp had a little different "character" from the QSC. Is it better? Maybe. It does sound great, there is no doubt about that. I'm just not sure if the difference is all in my head or not. It's too annoying to keep switching between the two amps, so I try to just go from memory (I'll be the first to admit I have an awful memory

). But last night, I thought I was experiencing a bit of what I've read so much about on this thread, particularly increased instrument separation and a bigger soundstage.

Ultimately, I just need to spend more time with it. But so far so good. Next step I believe is to give a SMPS a try. If that proves successful, then I might move forward with the monoblock idea. At a minimum, I would spring for a professionally machined and finished enclosure.

I'll try to find some time to post pics.

roymail · « **Reply #2859 on:** 26 Oct 2011, 03:15 pm »

I even went bare-minimum on my design: combined fuse+IEC, no power switch, two XLR inputs and four speaker binding posts.

Hey Matt, are you running a fully balance system? There is no mention of SE rca inputs. If the SDS-470 sounds no different than a QSC pro amp, I doubt this thread would be almost 150 pages. Not sure what's holding it back.

Glad you're having fun.