It's an op-amp based crossover... It really need +-15v, but I can just run +-24v and step it down to +-15v. 🙂TheMG said:
Received amp board and 24v PSU in the post, just in time for the weekend. Will stick some pictures up when I have finished assembling it.
I did some testing on this amplifier. Some very very crude testing, heck, maybe even considered "ghetto".
So here's what I did:
Hooked up the amp to a 24V SMPS, tied the output of the amp to a 25VA toroid transformer to use as a step-up, tied the output of the transformer to a 60W incandescent lamp. Put an ammeter in series with the output to measure current, and also measure the voltage with a DMM. Used a scope to ensure the output wasn't clipping.
Results:
119Vrms output
0.51A
Amplifier not clipping, but just under clipping level.
That's a nice 60Wrms delivered to the light bulb! Judging by how quickly the transformer was heating up, I'd say it was dissipating about 10W of power (60W through a 25VA tranfo, so that was to be expected). That puts the output from the amplifier at a whopping 70Wrms, pretty darn close to the 75Wrms on the spec sheet.
Note however that I was driving only one channel. Technically it should output nearly the same amount of power driving 4 channels, but I see heat could be a problem. The main heat sink got pretty warm, not an unreasonable assumption that it might get pretty hot driving 4 channels. Also, the diode did get pretty hot to the touch, but this can be removed as it's only there as a "fool proof" mechanism to prevent connecting the supply in reverse.
All-in-all, I'm pretty amazed at that little inexpensive amp. Not worthy of high-fi (due to white noise) but if you need something small, cheap, and LOUD, this is a good bet. Perfect for car-audio, PA, and parties!🙂
Video of the test setup coming soon.
So here's what I did:
Hooked up the amp to a 24V SMPS, tied the output of the amp to a 25VA toroid transformer to use as a step-up, tied the output of the transformer to a 60W incandescent lamp. Put an ammeter in series with the output to measure current, and also measure the voltage with a DMM. Used a scope to ensure the output wasn't clipping.
Results:
119Vrms output
0.51A
Amplifier not clipping, but just under clipping level.
That's a nice 60Wrms delivered to the light bulb! Judging by how quickly the transformer was heating up, I'd say it was dissipating about 10W of power (60W through a 25VA tranfo, so that was to be expected). That puts the output from the amplifier at a whopping 70Wrms, pretty darn close to the 75Wrms on the spec sheet.
Note however that I was driving only one channel. Technically it should output nearly the same amount of power driving 4 channels, but I see heat could be a problem. The main heat sink got pretty warm, not an unreasonable assumption that it might get pretty hot driving 4 channels. Also, the diode did get pretty hot to the touch, but this can be removed as it's only there as a "fool proof" mechanism to prevent connecting the supply in reverse.
All-in-all, I'm pretty amazed at that little inexpensive amp. Not worthy of high-fi (due to white noise) but if you need something small, cheap, and LOUD, this is a good bet. Perfect for car-audio, PA, and parties!🙂
Video of the test setup coming soon.
And at long last here's the much awaited video:
http://www.youtube.com/watch?v=A8Ygrwg7nsE
Struggled with getting the right format for it to work. Yep, I'm a youtube noob.
http://www.youtube.com/watch?v=A8Ygrwg7nsE
Struggled with getting the right format for it to work. Yep, I'm a youtube noob.
TheMG that is awesome 😀
I'm still building mine, it's coming along nicely but I'm still waiting for my speakon sockets to arrive, once I have got them in I will upload some pictures/url.
I did some testing over the weekend, nothing quite as elaborate as yours. although, I was quite surprised. I hooked up all my outdoor party speakers and it powered them with ease! Thats 2x JBL SB2 subs (4x8ohm 120w voice coils into 2 x 10" bandpass) run the voice coils paralleled so 2 x 4ohm loads. Then with the spare 2 channels I hooked up my mid-highs a pair of high passed JBL GTO937 6x9" car speakers, these are 2ohm and the amp loves them 😉 Unfortunately, I couldn't turn them up loud as my neigbours would complain so will have to wait to next weekend to really fang it.
I also did a bit of research into the white noise thing and found a great explanation on the net.
"Because of high frequency operation, power supply decoupling is very important. The switching carrier must be removed from all supply voltages to prevent it from degrading circuit operation. Finally, good high frequency circuit board layout technique is essential to minimizing EMI generation. As power level increases, switching currents traveling in high impedance board traces will generate significant electrical noise."
I think it must be that last part about the board layout technique.
the whole article can be found here:
http://www.extron.com/company/article.aspx?id=ts122001
I'm still building mine, it's coming along nicely but I'm still waiting for my speakon sockets to arrive, once I have got them in I will upload some pictures/url.
I did some testing over the weekend, nothing quite as elaborate as yours. although, I was quite surprised. I hooked up all my outdoor party speakers and it powered them with ease! Thats 2x JBL SB2 subs (4x8ohm 120w voice coils into 2 x 10" bandpass) run the voice coils paralleled so 2 x 4ohm loads. Then with the spare 2 channels I hooked up my mid-highs a pair of high passed JBL GTO937 6x9" car speakers, these are 2ohm and the amp loves them 😉 Unfortunately, I couldn't turn them up loud as my neigbours would complain so will have to wait to next weekend to really fang it.
I also did a bit of research into the white noise thing and found a great explanation on the net.
"Because of high frequency operation, power supply decoupling is very important. The switching carrier must be removed from all supply voltages to prevent it from degrading circuit operation. Finally, good high frequency circuit board layout technique is essential to minimizing EMI generation. As power level increases, switching currents traveling in high impedance board traces will generate significant electrical noise."
I think it must be that last part about the board layout technique.
the whole article can be found here:
http://www.extron.com/company/article.aspx?id=ts122001
Lol I've just had a dumb moment.
I could have measured the current and voltage BEFORE the step-up tranfo instead of guessing how much power the tranfo was losing. D'oh!
Oh well, that was far from an elaborate test and I mainly did it for fun.
Maybe I'll repeat this with my UCD400 build but this time with 8 100W bulbs.😀
Ok maybe not.
I could have measured the current and voltage BEFORE the step-up tranfo instead of guessing how much power the tranfo was losing. D'oh!
Oh well, that was far from an elaborate test and I mainly did it for fun.
Maybe I'll repeat this with my UCD400 build but this time with 8 100W bulbs.😀
Ok maybe not.
OK, have finally finished the amp. decided to stick a CPU fan on the heat sink and wire it to a switch incase of extreme use 😉
here are the pictures:
http://www.minihub.org/~colren/speakahs/minirig-sureelectronics/index.html
here are the pictures:
http://www.minihub.org/~colren/speakahs/minirig-sureelectronics/index.html
3 10W resistors to control fan speed?!?
I would of just used a variable voltage regulator and a pot.
What's the speaker setup? I notice you have some two-speaker connectors (speakon?) is it for bi-amping or are you powering 4 speakers?
I would of just used a variable voltage regulator and a pot.
What's the speaker setup? I notice you have some two-speaker connectors (speakon?) is it for bi-amping or are you powering 4 speakers?
yeah, the 10W resistors were just what was laying around. I will revisit the fan implementation later 🙂
I managed to pick up a 9m, 4 core, 2.5mm conductors speaker cable with speakons on ebay for $32 including postage, which I cut in half. So I have just run one cable (2 channels) to each side. I have 2 JBL SB2 subs and a pair of JBL GTO 947 6x9". I am feeding it with a Behringer UB1002 mixer which has main out and booth out. So I can adjust the level between the subs and the mid-highs. It's sounding awesome 🙂
I managed to pick up a 9m, 4 core, 2.5mm conductors speaker cable with speakons on ebay for $32 including postage, which I cut in half. So I have just run one cable (2 channels) to each side. I have 2 JBL SB2 subs and a pair of JBL GTO 947 6x9". I am feeding it with a Behringer UB1002 mixer which has main out and booth out. So I can adjust the level between the subs and the mid-highs. It's sounding awesome 🙂
have removed the 10w resistors and placed another 12v fan in series with the main one. Its small and fairly slow so hasn't added much to the fan noise level. Iv'e stuck it in front of the diode that gets hot 😉
Anybody blow a module yet? We torture them a lot and just blow a power supply from now...
Fredos
Fredos
Does anyone know what sort and size the blue capacitors are on the board? I accidently knocked one off but i don't get any wiser by the numbers on it.
Well, I just noticed this thread pop back up so I thought I'd share my latest torture testing of this amp.
Lately I've been using it as a variable frequency drive for an AC induction motor. I managed to run a motor that normally turns at 1800 RPM @ 60Hz to 9900 RPM @ 330Hz. Motor overclocking! lol
The amplifier didn't break a sweat.
So far, besides being an audio amplifier, I've used it as:
-true sine wave AC inverter (driving 60W bulbs)
-variable frequency motor drive
Dang this thing is surprisingly rugged!
Lately I've been using it as a variable frequency drive for an AC induction motor. I managed to run a motor that normally turns at 1800 RPM @ 60Hz to 9900 RPM @ 330Hz. Motor overclocking! lol
The amplifier didn't break a sweat.
So far, besides being an audio amplifier, I've used it as:
-true sine wave AC inverter (driving 60W bulbs)
-variable frequency motor drive
Dang this thing is surprisingly rugged!
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