So my “Sure D” is working and playing now for some long time. Because it does have potential I did made it complete using a housing and power supply.
The power supply is a Mean Well SP-100-24. I am using 2 channels so this 100W 24V will do to my opinion. I am using 84 dB sensitive Dynaudio speakers and it works great, it goes in living room loud if necessary.
The SP means that the switching power supply is ‘running’ at 67 kHz and not like the S model as can been found on Ebay at 23 kHz. It worries me that this 23 kHz is so close to the audio range. This carrier frequency will also be available on the 24 DC voltage, even it is low amplitude. I have no idea if terms of sounds it matters. I had some left-over SP supplies from work, these were use to upgrade some medical equipment because the original ones ‘died’ after a year of use.
The noise still worries me. At 1 W I can measure only -42 dB and that is low. In the late evenings I can hear the noise on my sitting position, this nees atetntion some how. In the past I had some serious hum problems in my amps, but this noise seems from the amp itself and can’t be eliminated. Next week I will try replace some caps on the board, and see of this will bring something. In a test setup on my workbench I can’t get it good either, I did try 3 different PSUs including a normal non-switching high performance lab PSU.
Using this SP-100-24 I measure 50W into 5 ohm at 0.3% distortion. After this it will clip very quick in its PSU limits.
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Hi guys
after wiring up a passive preamp i made, smoked one of the metal film resistors near the speaker outputs , there are 4 , for the 4 channels. R1 to R4. R4 is now a smokey dark disfigured colour. i have checked the bands and as far as i can see it is a
RED BLACK BLACK GOLD, which is 20ohm .5 watt resistor.
I just wonder if anyone has one lying about as something that costs a penny, im going to have to shell out £10 with postage, i have everything but in fact🙁
thanks for any help
after wiring up a passive preamp i made, smoked one of the metal film resistors near the speaker outputs , there are 4 , for the 4 channels. R1 to R4. R4 is now a smokey dark disfigured colour. i have checked the bands and as far as i can see it is a
RED BLACK BLACK GOLD, which is 20ohm .5 watt resistor.
I just wonder if anyone has one lying about as something that costs a penny, im going to have to shell out £10 with postage, i have everything but in fact🙁
thanks for any help
What kind of battery options would people suggest for this amp?
I'd like to put this amp into a penclosure with two CSS Fr125 drivers and a rechargable battery.
Cheers
I'd like to put this amp into a penclosure with two CSS Fr125 drivers and a rechargable battery.
Cheers
Ahem, seems i read that wrong, earlier replys say its brown,black,black, gold anyone got a 10ohm 0.5watt resistor for an ex leper? please
Alternative heatsink mounting...
I want to put this in an old car amp enclosure.
Now I have 2 options...
1) De-solder all components that are taller than the chip (most caps and inductors) and solder them on the reverse side... I can then bolt the board straight onto my old amp case and that will be the heatsink.
2) Simply lean over the 4 large caps, and glue the existing heatsink onto the amp case, with a some thermal paste to improve conductivity. I can also use the 4 holes on the outside of the PCB to improve mounting strength.
Which would be best? I'm tempted to go for 2 as it's will be quicker and easier.
Also, does anyone know is the heatsink has to be electronically isolated? I know it's anodized, but this isn't always ideal....
I want to put this in an old car amp enclosure.
Now I have 2 options...
1) De-solder all components that are taller than the chip (most caps and inductors) and solder them on the reverse side... I can then bolt the board straight onto my old amp case and that will be the heatsink.
2) Simply lean over the 4 large caps, and glue the existing heatsink onto the amp case, with a some thermal paste to improve conductivity. I can also use the 4 holes on the outside of the PCB to improve mounting strength.
Which would be best? I'm tempted to go for 2 as it's will be quicker and easier.
Also, does anyone know is the heatsink has to be electronically isolated? I know it's anodized, but this isn't always ideal....
So I was finally able to pick the chassis up from the Post Office and I'm impressed. everything was wrapped up, only one scratch on a panel and i can live with that (its on the bottom anyway). Very easy to put together, all the hardware was included (no instructions, but pretty simple to figure out. The panels are pretty thick and all the threads were good. I was very pleases how thick the front plate was, very nice. I figured I'd throw some pics of the setup.
Here is everything that was in the package. I was slightly confused why there were 7 panels....
this is a side shot showing the thickness of one of the side panels. all the panels, other than the front piece, were this thick. you should also be able to see the threaded nuts that are in place.
this is the front panel. very impressive (well, at least to me).
everything but the top assembled. as you can see, the front panel is just for "dress" and bolts to another panel behind it.
and now everything temporarily in place. i'm trying to see how to layout things inside. any recommendations?
Here is everything that was in the package. I was slightly confused why there were 7 panels....
this is a side shot showing the thickness of one of the side panels. all the panels, other than the front piece, were this thick. you should also be able to see the threaded nuts that are in place.
this is the front panel. very impressive (well, at least to me).
everything but the top assembled. as you can see, the front panel is just for "dress" and bolts to another panel behind it.
and now everything temporarily in place. i'm trying to see how to layout things inside. any recommendations?
I just recieved my 4channel and 2channel amps yesterday. Took 3 weeks as they said it would. They're both good looking boards, with a little bit of goo on them. The 4channel amp definantly has some output to it. I used a 19v 6.3a laptop PS and it has plenty of power for my application. And I only tried it through only one of my inefficient B3N speakers. Cant speak for sound quality yet, but all the sound was there. Unlike the 2channel amp where highs were attenuated. But that's a simple fix from the other thread for that particular amp. I'm pretty happy overall 🙂
SQ Kid said:
I would position the SMPS in a way that you can cut out holes for ventilation, it's going to need some airflow definitely.
Unless you plan on adding fans to the chassis itself, then you can probably position it whichever way you want.
If that was me though I'd be taking apart that SMPS, do away with the fan and mount all the heat-dissipating components of the SMPS on a heat sink at the back of the chassis. But that's just me, I like to avoid fans where possible.
Has anyone tested the ripple on the speaker outs at all?
I hooked up my scope today, and found around 400mv at around 170Khz sine... Isn't there normally a zobel cap and resistor to filter this? or is 400mv (rms) ok?
I hooked up my scope today, and found around 400mv at around 170Khz sine... Isn't there normally a zobel cap and resistor to filter this? or is 400mv (rms) ok?
Would it be terribly detrimental to the amplfier if it were placed in a sealed case? The amp will be fed 19v, and be running 4ohms on two channels, and 8ohms on the other two channels.
so i'm another step closer to having this thing together. minor setback in that channel 2 went on one of the boards, but i only needed 5 at the moment anyway (but still working with sure to find some sort of resolution). today the rca's and binding posts came. looks like i was only half awake when i ordered the posts, as i only have half as many as i need. no worries, they came extremely quickly, amazing price, and look great. i can't praise cnso138 for his goods. i ordered a set of 10 rcas and 2 sets of 4 binding posts, all for about $30 (he combined shipping to save me some money). here is a quick glimpse. maybe i'll get going this weekend and get this thing assembled....
400mV at 170kHz I wouldn't worry too much about it. It's way beyond the audible range anyhow. Btw, did you test that open-ended or with a 8/4 ohm load?
Anyways, I just got mine in today. Sound quality and power output were fairly satisfying for a $30 amp. However the one thing that irks me is that a lot of white noise can be heard, as others have already pointed out in this thread. This was immediately apparent so I can pretty much say I won't be using this in the receiver I'm building. My current setup (with car audio amps, don't ask) is dead quiet and I can't hear anything even sticking my ear to the speakers. However, it will make a nice small sized and low-cost portable amp that can pack a decent punch, so nothing is lost.
Bottom line: for the price, it's pretty decent. But it is clearly miles away from what I would consider HI-FI.
Anyways, I just got mine in today. Sound quality and power output were fairly satisfying for a $30 amp. However the one thing that irks me is that a lot of white noise can be heard, as others have already pointed out in this thread. This was immediately apparent so I can pretty much say I won't be using this in the receiver I'm building. My current setup (with car audio amps, don't ask) is dead quiet and I can't hear anything even sticking my ear to the speakers. However, it will make a nice small sized and low-cost portable amp that can pack a decent punch, so nothing is lost.
Bottom line: for the price, it's pretty decent. But it is clearly miles away from what I would consider HI-FI.
Well, after some more testing using a 24V 30A SMPS, it looks like this thing could make a pretty decent subwoofer amplifier. I was quite surprised at how much power this thing packs considering the price, probably not the 75W that it is rated at, at the moment I don't have a way to accurately measure the power output, but it's fairly powerful. If you were really mischievous you could use this thing to power a nice 4-driver subwoofer, hehehe. 😀
Another use I could see is for a small PA system on-the-cheap. Too much hissing (white noise) for normal home listening levels, but for parties and other situations where you want loud sound it wouldn't be noticed at all.
Finally, you probably don't want to power this thing using any less than 20V, as the output power drops considerably. Also don't use that included power jack cable, 24 AWG is way too small and you'll lose a lot of power over the cable, I recommend using minimum 18 AWG wire and using the wire terminals rather than the jack.
Another use I could see is for a small PA system on-the-cheap. Too much hissing (white noise) for normal home listening levels, but for parties and other situations where you want loud sound it wouldn't be noticed at all.
Finally, you probably don't want to power this thing using any less than 20V, as the output power drops considerably. Also don't use that included power jack cable, 24 AWG is way too small and you'll lose a lot of power over the cable, I recommend using minimum 18 AWG wire and using the wire terminals rather than the jack.
Got 1 for evaluation, provide 72 watts RMS into 4 ohms, 1 channel driven at 0.1% THD. I use the 24V 6A power supply from them, with voltage adjusted to 26V. The blocking schotky diode was removed and replace with a Jumper. Whith 4 channel driven, I got 58 watts each channel before PSU trip, with less than 0.1% THD. Bizarly, depend of the front stage used ( crossover, DJ mixer, or computer) channel 4 seem to ge easily into oscilation and zobel resistor blow few time...Never happen on other channel, maybe bad implementation of CH4 into IC...So I replace all 4 zobel with 10 ohms 5W...Nore more blow. We will maybe use this as multi channel lo power amp, for surround sound in club or for store use...Did'nt notice any hish that other people complaint, but not the more quiet I ever saw... A good 10 000uf 35V between power supply and amplifier help a lot when all for channel driven together...
just a slight update. got most of this thing put together. just waiting for the other half of the binding posts (as i ordered only half as many as i needed) and need to solder all the connections. almost there....
I tested with a 4 ohm load (sub)...TheMG said:
I'm not really worried it for SQ reasons, just more that it's unneeded power going thru my voice coil, but I guess 400mv will be next to nothing so it's not the end of the world...
Also, I pulled the heatsink today and put some thermal goo under there. Seems strange that they would ship it without goo... 😕
SQ Kid: Looking good - where did you get them RCA's from?
EDIT: I'm tempted to replace the zobel resistors also all as I've already had one smoking
Mike: the rca's and binding posts came from ebay seller cnso138. couldn't be happier with his products, shipping time, and costs.
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