| xplod1236 |
I have built my first chip amp today. I used the lm3886 chip. It worked fine, but I noticed that when I turned it up all the way, the speaker moved out a little. That means that I was getting dc on the output. Does anybody know what could be causing that? One more question: what's the smallest feedback resistor that I can use to maximize gain without the amp oscillating?
I was playing around with it so much, that I ended up frying the chip. Oh well....I have 4 more, and my next project is to parallel all 4 of them to drive a pair of subs. |
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| AndersZ |
| You're not using any input cap which means that you could get incoming DC from your preamp/source. |
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| peranders |
| xplod1236, how much DC do you get? |
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| Nuuk |
| A better way to discover how much DC offset you have on the output is to measure it! (Unless you have an unusually large number of speaker drivers that you wish to dispose of). ;) |
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| carlosfm |
68ohms from the mute pin to V-?
:confused:
1uf from Ri to ground?
:confused:
:bawling: |
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| UrSv |
| quote: | Originally posted by carlosfm
68ohms from the mute pin to V-?
:confused:
1uf from Ri to ground?
:confused:
:bawling: |
68 Ohms as per datasheet for the 0.5 mA.
1 uF for the HP at 88 Hz which might seem a bit high depending on what the initial test is for. |
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| peranders |
| quote: | Originally posted by UrSv
68 Ohms as per datasheet for the 0.5 mA.
1 uF for the HP at 88 Hz which might seem a bit high depending on what the initial test is for. |
Urban, how about multiply the 68 ohms with 1000? 68 kohms! |
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| Jax |
Poor mute transistor in the chip...
Rm <= (Vee - 2.6)/Im where Im > 0.5 mA.
For my 3886's with -33.6V Rm would be <= 62 kohm. I have selected 18 kohm.
68 ohm? :whazzat: |
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| carlosfm |
| I use 10k, and no cap. |
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| Jax |
| I forgot to add that I'm not using the cap either. :D |
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| UrSv |
| quote: | Originally posted by peranders
Urban, how about multiply the 68 ohms with 1000? 68 kohms! |
That would probably be more accurate by a factor of 1000...
Seing is sometimes as subjective as hearing I think... |
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| lgreen |
I hate to admit this, but once I used a 58 ohm resistor and it worked... but that was because of a brief mental lapse (not my last), since I've switched to 18K like Jax.
More on topic, how much DC offset is acceptable? I get .02 V DC at the output (and my speaker grills are not removable for a visual check). Is this ok? |
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| Jax |
<50mV is usually OK with most normal woofers. Purists want 0 always, though.
The offset varies a little with temperature so even if you balance it out with the + to ground resistor it will seldom be stable. You could add a DC bias servo but in my opinion those cause more harm than good. |
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| macboy |
| quote: | | ... I noticed that when I turned it up all the way, the speaker moved out a little. That means that I was getting dc on the output. Does anybody know what could be causing that? |
DC on the output, which varies with the volume control means that there is DC on the input. Insert a capacitor between the input and the 10 kOhm volume pot. This will create a high pass filter, which of course blocks DC. In order for it to also not roll off the bass, make sure to use a high enough cap. Make it 10 uF or more.
| quote: | | what's the smallest feedback resistor that I can use to maximize gain without the amp oscillating? |
You increase gain by increasing (not decreasing) the feedback resistor. Do not reduce gain to less than 10. Since the Gain-Bandwidth product of the 3886 is quite low (3 MHz), do not go over a gain of about 50 or so. If you increase gain to 100 or more, you will notice high-frequency rolloff. You will also get more noise (hiss) at the output with higher gain, so don't go crazy. If you need a gain of over 50, then you would get better sound quality by using a pre-amp stage consisting of a high quality audio op-amp or even discretes if you up to the task. Determine the proper gain by finding the ratio of your power supply voltage, and the peak voltage of the input source (e.g. line level is nominally 0.7 Vrms, which is 2 volts peak to peak, or +-1 V, so if your power supply is +-25V, you need a gain of 25 to ensure that the amp will deliver its full power when you crank the volume.). |
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| xplod1236 |
| Like I said before, I ended up frying the chip. I'll have another amp built in a couple of days, because I don't have time to do it now. The last amp was running off a 35 0 35 transformer, but the voltage after the caps was +-50. I know that the voltage was a little high, but it worked. I measured the output, and it was only putting out 4v to the speaker. So to increase the output voltage, I have to increasing gain, or do I have to use a preamp? |
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| lgreen |
| aahhhhhhh.... I'm no genious but I just read your threads, if you start building stuff I think you are going to hurt yourself. Especially if you make that 4 kW car amp you are talking about. Please please please read the data sheets for the chip amp, and about 10 web sites that tell one how to build it before going further, and a book on opamps would be good too. |
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| soundNERD |
Thats why ur chip fried.
The ABSOLUTE MAX voltage is 84V
Putting 100V into surely is the cause of the dead chip.
The LM3886 shouldn't just fry. I have really tested my 3886 amp. I use it for a sub, and I can't even count how many times it has been taken out.
And i cant even count how many times i turned it above how loud it shoudl go. as i said, it was for a sub, so it can be hard to hear clipping.
Reduce the voltage, and you won't fry the chip
just out of curiosity, how did you design yours? P2P, or PCB?
-Mike |
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| xplod1236 |
| quote: | Originally posted by soundNERD
The ABSOLUTE MAX voltage is 84V
Putting 100V into surely is the cause of the dead chip.
The LM3886 shouldn't just fry. I have really tested my 3886 amp. I use it for a sub, and I can't even count how many times it has been taken out.
And i cant even count how many times i turned it above how loud it shoudl go. as i said, it was for a sub, so it can be hard to hear clipping.
Reduce the voltage, and you won't fry the chip
just out of curiosity, how did you design yours? P2P, or PCB?
-Mike |
I just built another lm3886 and im running it off the same +-50v power supply. I have the chip on a heatsink, just like last time, but now I used the heat transfer paste stuff. Everything is wired P2P. I have the chip running for about 10-15 mins, and the heatsink is a little warm. I think that the last one fried because it got too hot. The protection circuitry was shutting the amp off pretty frequently, so it was running at over 100 deg. C. Oh well...still have 4 more.
BTW, could you post the schematic of your amp?
I want to use my amp for a sub too, but it only puts out 2v... |
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| xplod1236 |
| Here's a pic of my amp |
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| matjans |
you're pretty stubborn! :smash:
the datasheet tells you the absolute maximum voltage is 84v (thus, +/- 42 volts and YES, this matters, a lot). Either go on frying chips or use a psu with a lower voltage.
the by many people preferred (or agreed upon) schematics are found all around this forum. One good thread to start is this one (greg's ultimate gainclone) and a *very* good site to get started on building gainclones is nuuk's site . start by reading the basic gainclone pages. For a non iverting schematic check this post by peter daniel.
btw, i dont see any supply caps at the chip. very much needed (especially when building a sub amp!)
but seriusly dudu, lower that psu voltage ... :hot: |
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| xplod1236 |
| quote: | Originally posted by matjans
you're pretty stubborn! :smash:
the datasheet tells you the absolute maximum voltage is 84v (thus, +/- 42 volts and YES, this matters, a lot). Either go on frying chips or use a psu with a lower voltage.
the by many people preferred (or agreed upon) schematics are found all around this forum. One good thread to start is this one (greg's ultimate gainclone) and a *very* good site to get started on building gainclones is nuuk's site . start by reading the basic gainclone pages.
but seriously, lower the psu voltage... :hot: |
I dont really have a way to lower the voltage. I have that psu from a fried amp, and I dont want to mess with the windings of the transformer or use voltage regulators. |
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| matjans |
you could split the supply of one of the secondariy windings to get +- 25v. these amps don't really care whether GND is at 0v or not, they only care about the voltage difference. Only thing is GND would be floating at 12,5V (which could get you into trouble).
I'm very happy with +-18v! |
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| xplod1236 |
| I have 2 secondary windings 35 0 35 each, and I don't think it would be possible to split those. |
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| soundNERD |
A solution that works is just to use diodes. A diode drops the voltage (correct me if i am wrong) 1.2V per diode.
So, chain like 8 or so of them in line with the + and - supply to lower the voltage.
I used the same schematic you used, but I did it on a PCB.
If you really want a nice amp, I suggest going to the post LM3886 Pcb, and downloading the pcb design that bigparsnip kindly created for me. That isn't the one I used; i used a hand designed one, but that will definately work better.
The only difference is i used a |
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| soundNERD |
whoops, i guess i didn't finish it
"the only difference is" I used the original values for Ri and Ci as on the datasheet. I also used a smaller value for the mute pin. I don't have a mute switch.
I'll post some pics of the inside of my amp tomarrow, its late now.
-Mike |
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| xplod1236 |
| i just changed the feedback resistor from 33k to 470k, and it's so much louder now. I calculated that the gain increased from 4.3 to 48. I have the 10k pot turned up about halfway, and I'm not sure if it's clipping or if the speaker is making that noise. The speaker is a 6x9 that I bottomed out too much, and now the voice coil scrapes against the magnet. I'll hook up my subs to it when I have time and test it again. |
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| xplod1236 |
| One more question: my transformer is 35 0 35 and the caps are 6800 uf 50v. The caps raise the voltage to 50v. If I changed the caps to 35v ones, would that keep the voltage close to 35v? |
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| lgreen |
ahhhhh... the caps would blow up, either before or after your chip blew up. You see the 35 volt caps don't give you 35 volts, they provide smoothing of the voltage you already have, but they are only designed to smooth 35 volts max. Most people would never use 50 V rated caps at 50 volts, this is much too close to the failure point, and they will wear out faster, if not immediately.
So if you MUST do what you are doing here are my suggestions:
- COPY the design of someone else from the links above, don't use your own design. The design you posted is messed up.
- connect about 10 diodes from your pos supply to the positive input of the chip, and 10 from your negative supply to the negative input of the chip--- make sure you orient these the right way! This will give you about .7 volts *10 = 7 volts drop and make your 50 volts into a more safe 43 volts, but I would use even more (.7 volt drop each) to drop it to 40 volts or 37 volts. Make sure you read up on diodes so you have foward current flow (if you put them backwards you just wont get any current flow and wont hurt anything except maybe your speaker.) Also use diodes rated for 5 amps and 100 volts (or more) (foward and reverse voltage) so you don't blow these up either. Buy these diodes at radio shack if you have to. They also have the other components you need.
-keep using with the heat gunk, good stuff.
-Don't touch anything.
You are still scaring me, you are way over your head. |
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| Nuuk |
Zplod, are you for real or just winding us all up?
I'm not looking for a sainthood but I'll tell you, it took a lot of time and effort to create my Gainclone FAQ page precisely to help people in your situation. And I'm not the only one by a long way.
People on this thread are desperately trying to help you so do your self a favour, listen to what is being said and do some homework before you take further advantage of the good nature of people on this forum. |
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| carlosfm |
Stay clear of electronics, you can hurt yourself.
100 volts can kill.:RIP:
Electricity is not a toy.:whazzat: |
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| soundNERD |
Xplod,
Don't take this personally, but you really need to do more homework on the chip amp before you try to build one, especially a high-powered one.
I would suggest building a LM386 amp first. You can design it on a radioshack pre-etched ic board, and will run off a 9V battery.
It won't be able to power a sub, but it will get you into the theory behind chip amp operation.
Thats how I started, then I moved up to the LM383 (or something like that, it was an 8W chip, but is now discontinued). Then I moved up to the 3886. Nothing blew up, and everything worked as expected.
It sounds to me like this is a first attempt at an amp. Really, DON"T START WITH A HIGH POWER AMP, especially not the 4 3886 in parallel.
You have been warned, so don't come complaining to us when your new chip frys from 100V
Again, don't take anything above personal, were just warning you.
-Mike |
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| lgreen |
| Not to sound snooty, but unless you are joking with us you shouldn't work with electricity (I take my last post back, don't try it, you could hurt yourself). |
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| xplod1236 |
| quote: | Originally posted by lgreen
ahhhhh... the caps would blow up, either before or after your chip blew up. You see the 35 volt caps don't give you 35 volts, they provide smoothing of the voltage you already have, but they are only designed to smooth 35 volts max. Most people would never use 50 V rated caps at 50 volts, this is much too close to the failure point, and they will wear out faster, if not immediately. |
The transformer puts out 35v, but after the diodes, the voltage is 50v. The caps in the psu are rated 6800 uF 50v.
| quote: | So if you MUST do what you are doing here are my suggestions:
- COPY the design of someone else from the links above, don't use your own design. The design you posted is messed up. |
What is wrong with my design?
| quote: | Originally posted by Nuuk
Zplod, are you for real or just winding us all up? |
All this is for real.
I switched to a 25v psu. I'm not sure if it will put out enough power to run 4 lm3886s in parallel. There is a 2 amp fuse before and after the transformer, and the caps are 3300 uF 25v.
All I have to do now is tweak the value of the feedback resistor, to get the most power out of the chip. Then, I'll parallel 4 of them. |
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| Nuuk |
| quote: | | The transformer puts out 35v, but after the diodes, the voltage is 50v. The caps in the psu are rated 6800 uF 50v |
That may be OK but as a rule the caps should be rated at 1.25 times the voltage they are used at so you should be using caps rated at 63V for a 50V supply, or 35V for your 25V supply.
Each new post of yours gives rise for concern over your safety! :att'n: |
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| tbla |
are you still alive - give us a sign.........:att'n: |
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| theChris |
ok, you'll need some way to get a lower supply voltage. the max is 84V and you have 100V. an impportant second Q is how much current the transformer is rated at?
for that config the gain needs to be 10. ignoring the capacitor, this means the(resistor attached to the input / resistor attached to ground) +1 >= 10.
next, the lower limit will be given by the RC circuit of the cap and resistor that go to ground in the "feedback path". it is a good idea to make them large, but realize that the other resistor needs to be 10x more. |
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| matjans |
| read post #33 he has a 25v psu |
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| xplod1236 |
| quote: | Originally posted by tbla
are you still alive - give us a sign.........:att'n: |
Yes, I'm still alive. :angel: I got the amp to work pretty good. The gain is set at 48. One problem that I have with it is when I turn it up more than half-way, it sounds really bad. I can hear cracking, and it puts out less power than when it's turned up half-way. It only puts out 12v to the speaker. And the speaker is not the source of the problem. Is my gain set too high? |
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| theChris |
does the amp get hot fast?
i missed the 100V PSU down to 25V PSU. for the parallel chips you'll need a higher current transformer.
a high gain may be an issue.
do you have a complete design, including the PSU, and ratings on all parts? is the 25V PSU +-25V or just 25V? if it is just 25V, then you need to use the single supply schematic.
are you using the servos in the feedback network, or just resitors? what size resistor do you have on the ouptut of each chip? |
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| xplod1236 |
| I tried paralleling with one feedback resistor, but it didn't work. So now, I made a 2 channel amp. I'm using 2 lm3886s, one for each channel. The psu is +-25v with a 2 amp fuse. I'm not sure about the ratings. In the feedback network, I'm just using 470k resistors for each chip. Turned up about half-way (before I can hear the cracking), I can run a 3 ohm sub off each chip for about 45 secs before they get really hot. At lower volumes, I can run them for a long time, and they just get a little warm. Also, my heatsink isn't very big, but I'll upgrade to a bigger one once I get it working right. |
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| theChris |
ok, the chips have two issues -- gain difference and ossilitions.
in parallel, a 0.1 ohm resistance (copper wire, of x length), on each output, the feedback resitor attaches as close to the chip as normal to reduce common inductance.
the gain setting resistors must be chosen to be close on each IC, the idea is to have a very similar gain.
these two things are to keep current from one chip from flowing to the other chip. basically if you have a gain of 10 on IC 1 and a gain of 11 on IC, and a 1V input signal, you will hit the 5A limit on the ICs as you will have 1V difference on the outputs and about a dead short... the copper wire will make this 0.2ohm minimum, and close 0.1% tolerance resistors will make the gains closer.
ossilations can be helped by placeing capacitors near the PSU pins and bypassing them with 100nF ceramic (or other good RF type) caps. the datasheet has a lot of mods to get more stability. |
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| soundNERD |
The heatsink has to be very large. My first 3886 amp (a single chip) had a large but small heatsink, and when it got too hot, the chips would make a popping sound in the speaker.
You need a VERY large heatsink for these chips.
Also, you are running these in parallel, not bridged, right? If you were running them in bridged, you already solved your problem when you said you were running a 3ohm speaker. Thats only 1.5ohm a chip, and those chips aren't designed for much lower than 4ohm.
If not, are you sure they are paralleled, where the outputs tie together with a .1ohm resistor and not bridged, where the output of each amp drives one side of the speaker?
-Mike |
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| peranders |
| quote: | Originally posted by xplod1236
I tried paralleling with one feedback resistor, but it didn't work. |
Mister, I recommend that you read the AN-1192 and consider everything in this document as the truth. When you have full control over the situation, then it's OK to experiment. This document has a section about parallel connection. |
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| Nuuk |
| quote: | | My first 3886 amp (a single chip) had a large but small heatsink |
:confused: ;) |
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| tbla |
| quote: | | a large but small heatsink |
....now we're getting somewere.........:D |
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| peranders |
| ... he, he and this means....:confused::D |
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| tbla |
| quote: | | THE PLAIN TRUTH IS TOO SIMPLE FOR THE SEEKER AFTER COMPLEXITY, |
hey nuuk - too complex for you....:cannotbe: |
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| carlosfm |
| quote: | Originally posted by soundNERD
My first 3886 amp (a single chip) had a large but small heatsink, and when it got too hot, the chips would make a popping sound in the speaker.
-Mike |
:eek:
This thread is getting too scientific for me.:confused:
I just can't solve this equation.:bawling: |
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| matjans |
| hmm i thought it was my english but ... ;) |
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| Nuuk |
Well, the question here chaps is:
Is it wise to be foolish or foolish to be wise? :scratch1: |
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| carlosfm |
This is it:
"My first 3886 amp (a single chip) had a large but THIN heatsink, and when it got too hot, the chips would make a popping sound in the speaker."
:cool: |
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| tbla |
| quote: | | it got too hot, the chips would make a popping sound in the speaker |
would that be with all kinds of music or only popmusic........ |
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| theChris |
"You need a VERY large heatsink for these chips."
-really, you need to quantify this. a radiator from a car is a heatsink. is it large? very large? i have a 6x8x0.5 aluminum heatsink. big? a CPU heatsink. big?
as to xplod. a good idea would be to read the highpower app notes linked to in this thread. then if you have any specific questions, ask first then build. |
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| xplod1236 |
| As I said before, I tried paralleling with one feedback resistor, but that didn't work. Now, I'm using one chip for each channel. Each chip drives a 3 ohm sub. I tried it with a 4 ohm 6x9...same result. No matter whether it's hot or not, when I turn up the volume to more than half, it sounds really bad. Does anybody know what the problem is? |
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| soundNERD |
I knew somebody would laugh at my description :D
Let me explain more. The heatsink was large, about 3 1/2 inches wide by 1 1/2 inches tall, with fins about 1 1/2 inches deep. There were only 4 of those fins, though. That made the heatsink look large, but in operation, compared with a small heatsink. When I put a huge heatsink on it, which about 5 inches wide and 3 inches tall, with at least 100 little fins, the chip still got warm, but never overheated.
About the popping, when the chip overheated, an explosion sound in a movie or a boom in a song would make a loud pop, repeating for the duration of the sound. I think it was getting too hot and kept switching into thermal mode, or just the transistors were too hot to be operating at the volumes they were.
-Mike |
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| ecliptica |
I have built a amp with two lm3886's.. used a 2x28V/120VA transformer..
at first i had a too small heatsink and the lm3886 got so hot the solding melted at it legs. but, the sound was superb all the time.. i've never experienced any popping or something.
But i never tried to use the mute fuction on the lm3886, i built a seperate loudspeaker-delay unit instead.. worked really fine.
i used to caps at 10000uF/50v in the power supply unit..
xplod, if you want my schematics i got them in OrCad format.. |
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| ecliptica |
| One other thing that was quite mysterious i think, is that nomatter how hard i tried i couldn't get it to clip.. not until i tried to input 280V into the transformer instead of 230-250.. |
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| soundNERD |
So your saying that no matter how hard you pushed it's volume, you couldn't get the amp to clip before bringing up the voltage?
If so, could you please post those schematics in a standard image file?
and when you said there were 2 3886s, did you mean stereo, bridged or parallel?
Thanks!
Mike |
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| GregGC |
| quote: | Originally posted by soundNERD
So your saying that no matter how hard you pushed it's volume, you couldn't get the amp to clip before bringing up the voltage?
If so, could you please post those schematics in a standard image file?
and when you said there were 2 3886s, did you mean stereo, bridged or parallel?
Thanks!
Mike |
Entirely possible if the gain is not too high and the input signal is not to large either. The moment you apply higher PS voltage you increase the power disipated by the amp and the protection circuit will kick in and it'll start distort. This is one of the reasons when having 4 Ohms speackers you need lower PS voltage to minimaze the loss over the IC and nothing else. |
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| ecliptica |
SoundNERD:
yes that's what i'm saying.. even at maximum volume it didn't clip at all... we measured it with an osciloscope.. the curve was perfect..
BUT, it is possible that our schematic didn't allow it to clip.. i'm not sure..
and yes i can post my schematics in a day or two.. there nothing special really, but i'll post'em anyway.
when i say two i mean one for the left channel and one for the right.. stereo, but with the same powersource.
for supply for all the other small circuits in the amp. we used another transformator at 2*6V. |
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| ecliptica |
the lm3886 can handle a voltage off +/-10 - +/-42V..though the maximum peak voltage it can handle is somewhat higher.
Our powersupply peaked over +/-42V often..not very much but anyway. but it went fine anyhow. But, if you use a transformer with a rated voltage of, say +/-42 the actual peaks and max values will be far above what the lm3886 can handle.
I'm sure almost everyone here knows this.. but some seem not to.
By the way, we happened to make a BIG mistake in our construction.. we made a seperate speaker delay unit, which delayed the speaker a while right after we turn the amp on, but also cut the connection to the speaker in the very moment we truned off the amp. The ****** thing with this isn't really the function, but that we forgot to give the two 10000uF caps. a way to empty. So if we truned on the thing, played with it a while and then shut it off, and then suddenly on again all the internal fuses blowed
:rolleyes: ****... but it's easily fixed.. either we could make the delay to not work when turning off the amp, so the amp instead off getting quiet just continues to play for 5-10 seconds(and yes it will with those caps), or just give the caps a second way out to GND.
well that's a lot of blabla ;) |
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| peranders |
| quote: | Originally posted by ecliptica
One other thing that was quite mysterious i think, is that nomatter how hard i tried i couldn't get it to clip.. not until i tried to input 280V into the transformer instead of 230-250.. |
Herr Ume boy, can you take this once more slowly please. :eek: Clip what?
(Ume = Umeå, a town in the north of Sweden) |
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| GregGC |
| When you were trying to get it to clip did you have the speaker connected to the amp or not? |
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| xplod1236 |
| quote: | Originally posted by ecliptica
xplod, if you want my schematics i got them in OrCad format.. |
Yes, I would like to see some schematics. Can you post them as pictures? |
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| ecliptica |
well gothenburg boy ;)
With a standard inputsignal voltage, in room-temp, at max volume at the amp. it didn't clip at all.. which was measured with an osciloscope. In other words the curve on the oscilator-monitor had a nice shape alla the time and didn't have a flat top(didn't clip). Also the sound was very loud and clear, without noise.
We came a lot closer to clipping using a constant-volume sinus-wave anyway, than with music. Our powersupply-caps. was quite overdimensioned, which can have been a reason for the amp being so hard to get to clip.
And with clip or clipping i here mean that the amp, with the given powersource and input and output load, can't amplifie as much as it should which leads to an output that more and more seems like a square-signal.
please guys, don't take this the wrong way.. i'm not trying to say anything like "oh look at me my amp is the best whawha", the point, if i in this state hasn't forgot it, was to explain for someone, maybe xplod, that it could be a good choice to carefully dimension the power supply to get the best out of his amp. Cause we indeed played very loud with it.. that is with two 4Ohm speakers (in each box 2*1"tweeters and 2*8" basses)..
I had teachers to ask when i built my amp so that was nice, i did it as a part of the class "produktionsanpassad elektronik konstruktion" which in english is something like "electronic construction for production" at the university of Umeå. |
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| ecliptica |
| quote: | Originally posted by GregGC
When you were trying to get it to clip did you have the speaker connected to the amp or not? |
Yes one 4 Ohm speaker at each channel...(we tried without but we came closer with the speakers, we also tried with effect-resistors, but they burned pretty much)
when we raised the into-the-powersupply voltage we disconected the speakers as the sound started to feel like torture. |
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| ecliptica |
well i can't post it right now... but it's nothing special really..
Xplod, the schematic you posted at first on this thread, the only things that differ on my amp-circuit is i used a filter before the output to protects speakers from different things that can happen within the amp like self-swinging ;)(själv-svängningar)and also high frequences (very high, damageable for speakers).
Also i didn't use the mute function on the OP at all.
I think the dimensioning between components and power-supply and so on is the most important matter.. |
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| UrSv |
| quote: | Originally posted by ecliptica
well gothenburg boy ;)
With a standard inputsignal voltage, in room-temp, at max volume at the amp. it didn't clip at all.. which was measured with an osciloscope. In other words the curve on the oscilator-monitor had a nice shape alla the time and didn't have a flat top(didn't clip). Also the sound was very loud and clear, without noise.
We came a lot closer to clipping using a constant-volume sinus-wave anyway, than with music. Our powersupply-caps. was quite overdimensioned, which can have been a reason for the amp being so hard to get to clip.
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Clipping does not really depend on what signal you amplify. It's when your input signal is high enough to be amplified to a value higher than the maximum output. Regardless of whether it's sinus or music.
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And with clip or clipping i here mean that the amp, with the given powersource and input and output load, can't amplifie as much as it should which leads to an output that more and more seems like a square-signal.
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No problem at all. I've done it may times. Clipping is however a bit relative here as the internal protection circuits might do other things before clipping. |
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| peranders |
I was a bit confused but what you are saying is that your gain was not high enough and/or your signal source was too weak.
Mr Solförmörkelse, you don't have a pictures you want to share with us?| quote: | Originally posted by ecliptica
...happen within the amp like self-swinging ;)(själv-svängningar).. |
Oscillations :) |
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| UrSv |
| quote: | Originally posted by peranders
I was a bit confused but what you are saying is that your gain was not high enough and/or your signal source was too weak.
Mr Solförmörkelse, you don't have a pictures you want to share with us? |
Exactly. Nothing will clip if not driven to the clipping point.. |
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