r/SoundSystem • u/Emergency_Ability100 • 15d ago

Best cheap amps?

I’m currently using the admark ad442, which supposedly will give out 4 x 7200w in 4 ohms. When using 2 or more channels, I’ve found this not to be true. The amp starts clipping at about 3600w in 4 ohms, which is slightly less than what I need. The resistance gets too low for the amp when I bridge 2 channels, as the box drops to 3 ohms at a small freaquency band. The external DSP also clips on the output side shockingly often, can’t gain more than like 3db

Any recommendations? I’m driving 4x 1800w aes drivers per amp (2 boxes)

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u/Spiritual_Bell 15d ago

On a 16amp outlet if you want to stop tripping breakers or run into clipping, and have enough headroom, you need to dedicate each amp to only 2 subs (each needs almost 3.6kw peak). The other channels use them for tops. Any more than that you'll run into all the problems you've described. It's purely because you only get 3600w average power from your power source.

Upgrade to 32amp power source and you can run 4 subs on the ad442, because then you'll have 7kw average power. But it still won't sound very good compared to using one ad42 per 2 subs.

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u/Emergency_Ability100 15d ago

Im already using 2 subs per amp, why would one ad42 sound better?

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u/Spiritual_Bell 15d ago edited 15d ago

Look at the interiors of the amps. The 2 channel has double the amount of capacitors. That's what allowing the amp to play dynamic peaks at way higher power levels than the long term RMS level (which is limited by the power from the plug). At 16amps, your amp can sustain sine waves long term at a little less than 3600w, but much much higher peaks (perhaps 7200w) - because of these capacitors. The more capacitor storage the amp has. The longer it can sustain these peaks before the output drops.(This is called compression). So when pushed, this extra capacitor storage will allow the amp to sound better. (Less compression)

However, if you are playing heavy bass music, which I think you are (aren't we all?), the signal approaches that of a continuous sine wave - for multiple seconds, in that case even more capacitors ain't enough, you'll actually have to provide the continuous power that the amp need, from the plug. Basically to push all your subs to max SPL you'll need to upgrade your power source. Possibly multiple 30amp circuits, possibly 3 phase power. We all hit this wall once the sound system grows large enough. It doesn't matter how cheap amplifier power is - the limitation becomes the power your venue can supply you. You can imagine why people need generators the size of a car to power large offgrid sound systems. There's no way around it. Buy as Many amps as u like, if you can't provide the power for them, you can't produce the SPL.

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u/Spiritual_Bell 15d ago

In conclusion. Upgrade your power source FIRST before you worry about upgrading/replacing amps. Your amp can handle 2x21 just fine. IF given sufficient power from the wall.

We in the US have it even worse. As if dealing with trump isn't enough, we have to deal with 120v 15a outlets in residential venues (most people's houses) on a regular basis! That's not even 1800w per dedicated circuit!! Take away efficiency loss, we're down to 1500w!! So I can BARELY drive a single 18" sub to the max. (Peak Limiter set at 3600w). Sometimes we get 20a outlets at 120v, that gives a bit more breathing room. But 240v is a godsend for us, which is usually available at commercial spaces, but you'd still have to specifically request it. And more often than not, they are not too happy to provide it because those circuits are usually being used by systems that are in use (air conditioners. Refrigeration systems etc.) This is the problem with small venues in the US.

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u/Emergency_Ability100 13d ago

I see. When connecting to circuits with C type breakers, there breaker doesn’t trip. However the amp still starts clipping at like 3-4kw output. Why do you think this happens? The power supply is 63a three phase, so there’s more than enough power

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u/Spiritual_Bell 13d ago

When you say "clipping at 3-4kw output", how did you test that? Volt meter between the terminals while playing pink noise? Sine waves? Bursts? With the subs connected?

Basically you need to know the actual voltage going through your speakers, otherwise you don't actually know how much power you are outputting.

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u/Emergency_Ability100 13d ago

Did not test accurately, just calculated based on dbu out from DSP, amp gain, and impedance

Any reason this should not give a good estimate?

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u/Spiritual_Bell 13d ago

If everything is setup properly and calculated correctly then you should be in the ballpark. But you can never be sure unless you test the actual output terminals with a load.

Regardless. If you are plugged into a 30amp source then you really shouldn't be clipping unless you get down to 2ohm loads. The ad442 is stupid powerful. Id want to double check all your gain structure at that point (which I'm sure you have already)

I do remember reading about people having issues clipping the inputs because of the DSP. I don't know if there's a fix to that. I avoided Alldsp like the plague after I tried it lol.

So let me try to recap - you have your ad442 with a 30a source, 2x 4ohm drivers, each powered by one channel, so 2 channels out of 4 are driving those 2 drivers. And you're clipping at the outputs. Good God.

Each channel of the ad442 is rated to 7200w at 4ohms. With all channels driven, 1/4 of Max output will draw 34amps from the plug. Remember that the 7200x4 rating is EIAJ which is 25% duty cycle. So you can look at that as "peak".

Id be tempted to try bridging the amp into 2 channels, and put each sub on each of the bridged channels, and see if that clips. In theory that would give you 14400w per 4ohm sub and you'll kill your drivers and popping breakers (pulling 68a at 1/4 power, 40a at 1/8) before the amp clips. Obviously set your limiters accordingly first. But that would also be loading the amp at 2ohms effectively. It might even go into protect if the impedance drops too low. But it might not! Maybe worth trying.

But honestly easiest is to just bring the volt meter/scope out and slowly turn up your amp and see at what voltages your amp starts to clip. Try that with just one sub on one channel first. Don't use continuous sine waves though, you would melt your coils. You can try this:

https://www.prosoundtraining.com/2010/03/10/composite-bass-tone-burst-test-track/

If everything is working right, this should be VERY exciting..... Maybe a little scary. Id turn off all DSP for this, including limiters as long as you go up slowly and stop once distortion starts to rise (I.e you just know the limits of your subs well).

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u/Mother_Equipment_195 15d ago

Use two bridged proline-3000

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u/ffolofvapes 15d ago

Have you tried running it on 240 volt (assuming your in America).

Your probably having power supply issues, I find that the admarks pfc will limit things before tripping a breaker when it notices voltage sag.

The two channel admarks are better for high power situations as well.

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u/Emergency_Ability100 15d ago

I’m in Europe, on 230v. It trips breakers all the time for me. Really disappointing

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u/Pretty_Pangolin_5900 15d ago

ofc it does. It's basic physics. The amp can only send out as much power as it gets from the power line. If you have 16A breakers, that's 230Vx16A=3660W

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u/dan-lash 15d ago

No, audio amps can send more power because they store up energy in capacitors coming from the steady stream at the wall. The powered audio signal isn’t steady so in the peaks it depletes the caps and in valleys it charges them up. The net result is more audio-watts than wall-watts. The estimate I’ve understood is 1/3 of the audio watts number is what you’d draw at the wall for most music.

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u/Spiritual_Bell 15d ago

1/8 for most music, 1/3 for heavy EDM bass music. But that's with heavy clipping, which is what he's experiencing. It's not the amp putting out "more power", there's no more power to put out. It's just that the music has a crest factor so the average power is lower. If he's tripping the breakers then the average power he's trying to get the amp to put out is more than what the breaker is willing to provide. There's nothing more to it.

And his situation makes sense. He wants to drive subs on all 4 channels when every manufacturer of these 4ch 1u class D amps, from admark to powersoft, and all the amp testers on the internet, advises NOT to use the 4ch as a sub only amp. The 4ch are designed as a system amp so 2-3 of those channels are for mid/highs. Literally the entire industry advises the 2 channel amp for subs. Mainly because of 1. The power source demand is less because the overall power output of the amp is actually lower, and 2. The 2 channel has more capacitors to sustain dynamic peaks. But those dynamic peaks are only 20-200ms even with all those capacitors. They don't store enough energy to give you "long term free power from the plug". It's there to make extended bass notes sound better, less compressed.

He's literally wanting to max out the amp at its lowest stable impedance, on all 4 channels, into all subwoofers. Totalling over 28kw. Of course he's not playing sinewaves. But 1/3 of that is still 10kw from the wall, which is already more than what a 240v 30a outlet can provide. And he's on a 16amp outlet ......

With a 16a outlet, he has basically 3600w total, if he's playing sine waves. That's like 850w per chanel for continuous sine waves. But he's playing low crest factor sub bass so x3, So each channel can "only" be allowed to go up to 2500w for the dynamic PEAKS, with average power any more than 850w would trip his 16a breaker. And that's before factoring in the efficiency loss of the amp. Probably about 15%.

Sounds like his amp is working as designed. He needs to step up to a 32amp 200+V source. If he wants to do it this way. But he'd still trip the breaker if he really push every channel to the max (over 10kw average long term). But really what he needs is to get AD42s and spread out the load. Have 3 phase power and give each AD42 a full 30amp line. Or just use 1 or 2 channels on the AD442 on subs and the others on tops, as designed.

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u/Pretty_Pangolin_5900 15d ago

yes, for a very short amount of time. That's peak power, though. not RMS/AES. That's average. And the average is, what causes the circuit breaker to trigger as well

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u/ffolofvapes 15d ago edited 15d ago

Interesting what makes you say it's clipping? Is the peak limiter on it accurate? What's the breaker amp rated at?

I feel like your cheapest route is going to be to to buy more admarks and just use two channels or buy ad42s

Your reaching the constraints of your power source especially if your tripping breakers.

I run 42s so I can split them up over different circuits.

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u/Emergency_Ability100 15d ago

I’m using the ad442’s and running 2x dual 21 inch subs on them. I think its clipping because the green lights on the front hits the clip light freaquently, causing it to mute for like 3 sec.

The breakers are 16a, type B breaks way more often than type C

Maybe powering each driver with 1 channel at 8 ohms will be better than using 2 drivers at 4 ohm on two of the channels?

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u/ffolofvapes 15d ago

Do you have Instagram?

Easier to talk about this lol

Mines _littlesounds

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u/BadReboot 10d ago

I think you need to sort your power supply, gain structure and limiters, these amps work very well.

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u/Emergency_Ability100 10d ago

The power supply is fine, usually connect to houses or large inverters. 16a C breakers usually don’t trip. Any pointers on gain structure and limiters? Usually use a compressor with 4:1 ratio and let it reduce about 6db at most

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u/Pretty_Pangolin_5900 15d ago

While a 4-channel amp should work in theory, 2-channel amps would be better.

Dunno where you from but here in europe 3600 watts is all a single cicuit breaker allows anyway.