Sure-Electronics.com class d amps

Status
Not open for further replies.
Jump to Latest
#201
alright, so suppose its still not the most optimal setups, but instead of going with 2 of the 24v 6a smps from sure, i ended up purchasing a single 24v 14.6a to power my pair. since i'm currently only going to be using 5-6 of the 8 total channels, it should do the trick for now. here's to anxiously awaiting the new case and ps
 
#202
buzz1939 said:
And of course there are a couple of errors ... this corrected version takes out the 80% efficiency factor (used to calculate the output) when calculating the amperage input required and fixes a formula error.

I added a 2 ohm column just for fun. Those figures may be especially hypothetical.
Code: 
Watts / Ch - Output				
			ohms	
	2	4	6	8
volts				
12	19	10	6	5
18	43	22	14	11
24	77	39	26	19
26	91	45	30	23

Assuming				
80%	 efficiency		
67%	 of max power, to reduce distortion to 1%		

Amps / Ch - Input				
			ohms	
	2	4	6	8
volts				
12	 2.0 	 1.0 	 0.7 	 0.5 
18	 3.0 	 1.5 	 1.0 	 0.8 
24	 4.0 	 2.0 	 1.3 	 1.0 
26	 4.4 	 2.2 	 1.5 	 1.1
Click to expand...

Sorry if this is going to sound noob but i'm a little confused as to how volts and amps work together towards power.

So according to that chart a 24 volt power supply will yield 39 watts at 4 ohms. That I understand (i think). On the amps chart it says that given you have a 24 volt power supply that does 2 amps you can drive each ch at 4 ohms...am i reading this correctly?

So something like this
http://cgi.ebay.com/LAPTOP-AC-ADAPT...ryZ11168QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

would be able to power all 4 of the amplifiers ch at 4 ohms producing 39 watts per ch?
 
#203
That 2.65 amp power supply would only power one channel at those levels - both tables are per channel! You'd want 10-12 amps for four channels if you're going to the maximum useful power output.

"according to that chart a 24 volt power supply will yield 39 watts at 4 ohms" - right - per channel. That's the theoretical limit assuming you don't want to exceed 1% distortion. *

"On the amps chart it says that given you have a 24 volt power supply that does 2 amps you can drive each ch at 4 ohms...am i reading this correctly?" Well, since the labels are still volts on the rows and ohms on the columns, it's more like it's saying that at 24 volts, 4 ohm speakers will draw up to 2.0 amps of current - per channel - at the maximum power that delivers no more than 1% distortion. *

- - - - -
* Wim's measurements suggest that actual results might be 20-30% higher that the hypothetical math - which is certainly possible, it's not hard to explain how that might be the case. So add some cushion to the amps needed if you plan to operate it at those wattage levels.
 
#204
buzz1939 said:
That 2.65 amp power supply would only power one channel at those levels - both tables are per channel! You'd want 10-12 amps for four channels if you're going to the maximum useful power output.

"according to that chart a 24 volt power supply will yield 39 watts at 4 ohms" - right - per channel. That's the theoretical limit assuming you don't want to exceed 1% distortion. *

"On the amps chart it says that given you have a 24 volt power supply that does 2 amps you can drive each ch at 4 ohms...am i reading this correctly?" Well, since the labels are still volts on the rows and ohms on the columns, it's more like it's saying that at 24 volts, 4 ohm speakers will draw up to 2.0 amps of current - per channel - at the maximum power that delivers no more than 1% distortion. *

- - - - -
* Wim's measurements suggest that actual results might be 20-30% higher that the hypothetical math - which is certainly possible, it's not hard to explain how that might be the case. So add some cushion to the amps needed if you plan to operate it at those wattage levels.
Click to expand...

Thanks...I think I understand. It looks like after the amp, power supply, and crossover components I might be better for with a 2.1 plate amp for madisound.

(i'm trying to find something to power a 2.1 portable box for my ipod)
 
#205
ricebox said:


Thanks...I think I understand. It looks like after the amp, power supply, and crossover components I might be better for with a 2.1 plate amp for madisound.

(i'm trying to find something to power a 2.1 portable box for my ipod)
Click to expand...


On second thought (for the sake of choices) what would be a good power supply for this amp if i wanted to run 2ch @8 ohms with about 10-15 watts and parallel the the other to channels to power the a 4ohm sub (read in an earlier post that this was possible) for 20 to 40 watts?
 
#206
ricebox said:



On second thought (for the sake of choices) what would be a good power supply for this amp if i wanted to run 2ch @8 ohms with about 10-15 watts and parallel the the other to channels to power the a 4ohm sub (read in an earlier post that this was possible) for 20 to 40 watts?
Click to expand...


you cant parallel the other two channels to get any more power unless you're running a lower impedance speaker (2ohms? 1 ohm?) however, it would probably be easier for you to find a dual 4 ohm woofer, and run that 🙂 or, as it seems you're just making a small speaker system, an isobaric setup with two 4ohm woofers might be the go for your subwoofer.

anyway! back to the question! lol

a 24 volt, 6 amp powersupply from sure electronics would be good... but I dont think you wanted that...

a laptop powersupply would be the next best option...

edit:

http://cgi.ebay.com.au/AC-Adapter-P...ryZ31510QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

🙂
 
#207
TWOJZ said:



you cant parallel the other two channels to get any more power unless you're running a lower impedance speaker (2ohms? 1 ohm?) however, it would probably be easier for you to find a dual 4 ohm woofer, and run that 🙂 or, as it seems you're just making a small speaker system, an isobaric setup with two 4ohm woofers might be the go for your subwoofer.

anyway! back to the question! lol

a 24 volt, 6 amp powersupply from sure electronics would be good... but I dont think you wanted that...

a laptop powersupply would be the next best option...

edit:

http://cgi.ebay.com.au/AC-Adapter-P...ryZ31510QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

🙂
Click to expand...

very cool thanks....so if i were getting 15 watts @ 8 ohms and wired the 2 ch parallel on a 4ohm woofer, would I get 30 watts?

Edit

I'll probably end up going with a laptop power supply like you listed...THANKS
 
#208
ricebox said:


very cool thanks....so if i were getting 15 watts @ 8 ohms and wired the 2 ch parallel on a 4ohm woofer, would I get 30 watts?
Click to expand...


yes, but, you could just run the 4 ohms off 1 channel, and get the same power anyway 🙂

you might need slightly higher than 18.5 volts to get the power you want... but, its not going to make THAT much difference, however, I would suggest you try to get more power to the subwoofer at least 🙂
 
#209
TWOJZ said:



yes, but, you could just run the 4 ohms off 1 channel, and get the same power anyway 🙂

you might need slightly higher than 18.5 volts to get the power you want... but, its not going to make THAT much difference, however, I would suggest you try to get more power to the subwoofer at least 🙂
Click to expand...

hum...what was the benefit in running 2 ch parallel stated earlier in this thread?
 
#215
TWOJZ, how high do you have the voltage dial turned on the 24v 14.6a PSU? Have it maxed (I think that is clockwise)? I have the 4-ch with that psu as well.

Also, should the amp GND go to the/an amp chassis? (still looking for a cheap one)

Lastly, any comments on fan noise coming from the PSU?

Thanks all
 
#216
ibilisi said:
TWOJZ, how high do you have the voltage dial turned on the 24v 14.6a PSU? Have it maxed (I think that is clockwise)? I have the 4-ch with that psu as well.

Also, should the amp GND go to the/an amp chassis? (still looking for a cheap one)

Lastly, any comments on fan noise coming from the PSU?

Thanks all
Click to expand...


only running mine at 24 volts at the moment, I wouldn't really wanna risk it at 26 volts just for the sake of a few extra watts.

pretty much everything should be grounded, as a starting point, however, it could lead to ground loop problems, so try it and see 🙂

I mean, if it has a ground connection, connect it to ground! (the amplifiers metal case aswell, assuming you use a metal one 😛)

the fan in my PSU has never come on... its thermally controlled, and the PSU hasn't gotten hot enough.
 
#217
🙂 i too also have the same setup with the Sure amp and the 24v 14.6A SMPS, but ive put my voltage upto 26V. And my observation is the same, the SMPS is so capable, it never gets warmed up, either heatsink on the amp, or the SMPS.

Sound fantastic for the pennys, so much so i bought me mate one and he loves blowing his speakers up with it😀
 
#218
ibilisi,

I'm still awaiting the arrival of mine, but this guy seems to have some great prices for cases.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230206044823&ssPageName=ADME:X:AAQ:US:1123

I got an all aluminum, model LL-1924A, shipped via Air Mail, for $110. If you want to go with one of their painted case, the cost is much cheaper. Plus, they look to use thicker guage metal than Parmetal for their cases. I'll make sure you snap some shots when it arrives.
 
#219
Thanks for the info all. I'll keep considering my chassis choices...

I'm collecting other parts:

Fuse Holder

IEC Socket

Any suggestions for an illuminated switch?

Also if you would humor me, I am a newbie at this, so IEC ground should be connected to chassis. However, should the AMP, and SMPS ground also be connected to same chassis ground? I noticed that there are a few gainclones that use IEC ground connected to a copper bar linked to all ground points, however

Thanks in advance.
 
Status
Not open for further replies.
Top Bottom