In all my years of pro audio, speaker electronics always baffled me. Thanks for giving such detailed information!

I've been trying to explain this for soooooooo long to so many blank stares. Masterfully explained AGAIN sir!

Took my understanding to a whole new level Dave! I will need to watch this one a few tomes over before everything is sunk in my head.

Wow! This is really interesting and fun stuff. The best part of the lesson are the slight diversions. All the related side topics Dave speaks about makes it extra interesting. Great teaching gift.👍👍👍

I really like how you explained your theory about setting up an amplifier to speakers

I’m an 60 year old punk rocker who was fortunate enough to have met Dave years ago at shows at the Olympic. As a young guy in a band, you were always sort of in awe of the tech guys at big venues, but Dave was extremely nice and helpful back then as he is in these videos. He obviously is very passionate about his knowledge and sharing that. He is my audio hero. I have been in my job now for 25 years as the house audio engineer myself in a large performing arts center, where I take care of several large venues, including the 70volt stuff, as well as line arrays. When I first started learning and blowing stuff up, I would always use bridged mono set ups ( as I was the only local guy with a crap PA system that would do basement punk rock shows) and this brought back a TON of good memories. Thanks again Dave. Keep up the great work

Fantastic stuff Dave, I have never used bridged mode on my amps, you have tempted me to give it a go..... Smashing

And this is why I like how easy it is to rewire NL4 connectors. Nice one sir Dave :-D

1000W balanced line 😂 So funny... but so true. Thank you Dave for your crazy, fresh and useful videos, I never miss one !

It's always a pleasure watching your videos. Thank You

Wow this was interesting thanks Dave. Cheers!

These videos help keep the brain in the game while we’re locked down here in OZ. Your mis-matched in a box example was my suspicion with a particular company. All in bridge mode. One OO box in the rig always looked like it was fighting itself. Uneven extrusion. I often disconnected it and ran 3 of 4 boxes. Cheers Dave

Wow! Good stuff Dave 👍🏻

I also run my bass cabs this way.... LOVE IT!!! I run old school, Crown.. Crest. QSC. Amps with Cerwin Vega earthquake 18"s does the job no doubt, but I'm so tempted to upgrade to some newer rigs! This guy is pretty informative and definitely gets the creativity flowing FoSho! Big ups Dave🤘

Thank you for your videos mister Rat, I am learning a lot from them 👍

Such an eye opener.

4:16 explains EXACTLY why an amplifier into a single bridged driver sees half the load. There's literally a point at about half the voice coil where it is "center tapped" and there is zero voltage to ground. Dave explained it with two speakers. I like this explanation.

It all goes back to electrical theory. You have to understand the basic theory or foundation of Ohms law, watts law, etc... Years ago, I was helping a then friend do sound for a small festival. NOT mixing, just setting up. I tried to explain to him that his speaker cables were too light gauge wire, and he should move his PAs up front under the stage and keep the cables as short as possible. The sub cables and connectors would actually get warm. I/2R loss. My background is in industrial electrical and electronics for over 33 years. With years in commercial electrical construction. When you install sound systems in auditoriums, movie theaters, and stadiums, your distances are sometimes very long. Amps are hidden in inconspicuous places. Even inputs are subject to line loss. Its crazy stuff, but very interesting. Dave is a great teacher. Pay attention bc there's a lot to learn!

I've used bridge mono to get the full output of a power amp but had no idea you should jump the negative to a hot terminal on the speakers which logically seems weird and counter to layman's polarity know-how to get the most out a matched speaker scenario. I'm gonna have to read-up or maybe you could do a video showing the wiring w/ a small power amp and speakers? I feel like me attempting it would blow something. Always helps to see it vs told. Thanks for the video Dave. I enjoy these.

Dave, good explanations. One minor thing - when talking about power loss due to resistance in the speaker wires. As far as I know (could be wrong), most power amp stages use some sort of voltage feedback for linearity. And, at higher impedance levels (like 8 ohms) the max power they are able to provide will be voltage limited. So if you are talking about power loss vs. max power available, there is actually a squared factor rather than a linear factor. In your example with 8 ohm load, and two wires of 1 ohm each, it's true that 1/5 of the power delivered by the amp will be dissipated in the wires, and 4/5 in the speaker. But also if that amplifier is rated at 500Wrms at 8 ohms, and is voltage limited (at 63Vrms), then loading it with 10 ohms means that it will only be able to deliver 400W. Then, only 80% of that will get to the load because 20% of the voltage drop will be across the wires. So the speaker will only end up with 320W, which is 64% = (0.8)^2 the rated power of the amp driven at max input level. If there was current feedback, then the output voltage would increase automatically with the higher total load resistance to keep the output current constant, and then there would only be a 20% loss.

Hi Dave!. Great explenation!....As you know there are too many fake information around... But, if I can, I would like to add some details, starting from voltage side instead of power.... So... Based on your exemple, let's say that the amplifier give to the speaker 70.7V (peak) each channel. Each channel is connected to one 18"@8ohm with two cable of one ohm resistance. So, each channel see 8+1+1=10 ohm resistance load. like you said! 70.7V on 10 ohm meaning (P=V^2/R) 500W. Each cannel delivery 500W to each speaker.. so the amp delivery in total 1000W. Due to loss on cable, on 18" cone we have only 500*8/10= 400W. we loose the 100w on cable. Now. If we connect the amplifier on Bridge mode we have, under the same condition, 70.7*2=141.8V. The amp in this case see 8+8+1+1=18 ohm load On 18ohm load at 141.8v the amp delivery (P=V^2/R) 141.8^2/18= 1110.8W. Here the first point. In dual mono the amp give us 2*500=1000W. In bridge he give us 1110.8, so 110.8W more. At the speaker we have 1110.8*16/18=981W. We lose 1110.8*2/18=123W The second point, at the end, In dual mono we give to a double 18" 800W, in bridge 981W so 181W more, with the same amplifier and with less expensive cable... That's grat!

Great video. 😀👍♥️

I always enjoy the sine wave at the end of your videos. :)

Awesome! 🤯

Dave - great stuff as always. Here is my question; So for example:- running 2x 18” drivers in series on sub duties - uses a lot of power in this cross over band - I’ve always thought that running drivers in sub land in series is a no no - purely due to the reason that once voice coil is essentially acting as a resistor to the other opposing voice coil. For example 4mm speaker wire might have an impedance of say 1 ohm. But the voice coil has a impedance of say 8 ohms… This means in a series configuration one driver 18” driver (let’s say driver B) sees: 1 ohm - cabling (-) 8 ohm - voice coil A (variable to some extent cone moves) Driver B it self - 8 ohms Cabling - 1 ohm (+) So essentially once voice coil is power limiting the other. Aka the dancing electrons/pixies have to pass through a piece of small voice coil wire to get to the next driver - essentially using the thinnest wire you could to complete the circuit. Does this make sense ? In mid and Hf bands - the current draw isn’t as excessive or as large so not so much of a big deal - but in sub land, parallel. If you need more lows, add boxes and amps. However I see no problem using a amp in bridge mode driving a pair of 18” drivers in parallel. Really with the double up of capacitors (of course dependent on amp topology / class) gives a much better damping factor and immediate current draw capabilities! Thoughts 💭🤔?

Thank one more time!

Interesting, thanks. My only experiances of bridging (actually, Un-bridging) have been where people have asked me to check their rig out, as it wasn't sounding good. Having found the amps bridged, I've completely re-wired it all for straight forward stereo, checking that all the balanced inputs / outputs are properly balanced (ditching the XLR-TS jacks for example) and it has invariably sounded 10x better, with people generally saying ' :o Wow, what did you do?' or things to that effect. This led me to believe that bridging just sounds rubbish, although I haven't done much experimenting, and most of the rigs I've done this on have been 'average' at best. I brought this up on Speakerplans forum years ago, and pretty much every pro agreed, and it was more the newb's / amateurs / hobbyists that wanted to do it, because, 'double the power for free' sounds like a great idea, doesn't it? in theory. I always figured it was just a cheap trick to make small amps bigger, if you had more amps than speakers, and it would always be better just to get a decent sized amp in the 1st place. Anyone else have any input on sound quality? What happens if you lower the gain control on one of the two amp channels? does DC go off-set? or just quieter?

Brilliant video, so fascinating. Can't wait to get my head around this one. Can anyone help? I always thought inverse polarity has a cancelling effect on the signal. I'm assuming one of the 18" speakers is flipped around so both are operating in sync. I love mental challenges like this! 🙂

As a matter of fact, I used to use the inverting outputs of my Crown VFX-2A crossover to bridge an amplifier that didn't have a bridging switch. I also used to invert the right channel in a stereo pair, and wire the speaker outputs of the right channel in reverse polarity. It was a cheap trick to give a tiny bit more headroom on transients, so one channel pulled from one power supply rail for the initial impulse, and the other channel pulled from the other rail at the same time. It didn't work with tightly regulated power supplies, but with some amps could deliver just a little more power before clipping that way.

Dave, I think the power of each amplifier doubles when you run them bridged. So, in your example, if previously each amp is driving 500w into the cabinet, when bridged, they will *each* drive 1000w into the cabinet. The reason for this is that the impedance they each see halves, and so they each produce twice the current, and hence twice the power. Of course it's easy to run out of current delivery in an amp, so it might not be realistic to expect the power to go up by x4, but that's what the math says :) Thanks for an interesting set of articles and sharing your passion for audio.

Damn, I need to come back to this video some time later.

Am I missing something here? I'm not an audio professional, but my understanding was that bridge mono mode flips the phase of one channel and then wires it in series with other channel with positive and negative reversed. It thus becomes a push-pull amplifier with one channel driving positive to ground, the other negative to ground. This is then fed into the speakers wired in parallel to halve the impedance. The advantage is that the speakers are isolated from ground and immune to noise.

What do you think of the newer amps (like QSC CX-Q) that can run channel pairs in parallel? Have you seen that?

Burning question. I haven't been able to get an absolute answer on how the reversed polarity to channel 2 power is being used from a bridged amp. Does channel 1 (+) hit the speaker positive terminal with half the amp power and channel 2 positive act as a negative and pulls the speaker back with the other half of the amp power? Or, does it feed both sides of the power amp to the positive speaker terminal to push the cone and the negative terminal just acts as a neutral/ground path? It wasn't described to that effect but I'd love to know the answer. Thanks Dave. You are the man!

Dave knows his shit!

Thanks for everything dave, 1 question what if we run 2 heats, 1 of them are push-pull in the other one is solid state, both delivery the same amount of power and are bridged in the center tap mode, that could affect the signal the goes to the speaker??👍👌

Back in the day I ran a 3 wire setup, Bryant 15A 125V twist locks. Ch A lows, Ch B low mids. The - wire served as a neutral more or less. The only time Ch A & Ch B were in phase were at the crossover point which was down -6db. Worked well. Didn't invert Ch B on the amps, the difference was the frequency bands within which they operated.

I rum a 15 inch sub at 8 ohms on a class D bridged amo. The sub is 600 watts and the amp 1200 watts. Sound great with good headroom

So basically if your running 2 subs (any size) it’s gonna be more efficient to run them in bridged mode rather than splitting a mono signal into a stereo pair due to the resistance of the speaker wire. Is this something you consider at large events? Because you usually have more than enough budget/gear that this wouldn’t be an issue. Your not limited on amp power when your using top of the line amplifiers. I guess this could possibly play into truck space

Hi, Dave. Just stumbled upon your channel randomly and actually have a relevant question. Maybe a little out of your wheelhouse, but I suspect you have the answer. I have a small multi function guitar amp that is stereo, but uses two built in 4"speakers. It sounds pretty good, but I'd prefer to be able to connect it to an external cab. Now I can easily install a couple of switching jacks and connect it to two spare 4ohm driver's, but I'd rather bridge it to one cab if possible. So if I have continuity between the negative speaker terminals and the chassis, does that mean I can bridge it? Thanks very much for sharing your experience.

superb video! thank you

Very interesting video, i run 3 single 18" subs (8ohm each) with a single amp and 25m speakon cable. I've always used the parallel mode so i can keep a minimum of 4ohm load, and i've always avoided 2ohm bridge mono mode since i've been told that the damping factor is reduced in such mode (bridge) which cause less control in the driver movement. Is this way of thinking correct? I always limit half of my amps power per channel into my drivers so i keep headroom and clean signal Respect Dave rat!

Nice explanation and didn’t know you can bridge separate mono blocks… Question; Wouldn’t running a bridged amp to 2 speakers in parallel give you the most power and least resistance. This would give you a mono 4ohm (plus cable resistance) giving you almost double the wattage… Do I understand this correctly? (assuming the amp is stable/capable of 4ohm bridged)

Dude..... wish i would know this when i was 16 and had 2 same model 300-200 Watts... great stuff now days everyone is going with active speakers, I see ususally deploy Lacoustics system, passive. I like passive I believe are easier to run,(my system is very small compact. Tri amp, 3 way low, mid, High, thru 12GA) vs active where you have to run power to each box then feed audio signal top and bottom. I seen some DAS have CAT7 ins and out, witch is very cleaver way to reduce cables.... Do you prefer passive or active, I would like to know you opinion pros and cons. Thank you.

Hey dave. Once again you are too interesting. I should be asleep. Im running conference audio at the swedish pavilion in the expo2020 in dubai tomorrow morning. Just had to see this. Ive only used bridge on too small amps to get more power. Still into parallell loads. For example a 900w crest ca9 amp into a powerful 8 ohm jbl sub. Just a work around with 2 small amps for a setup rather than 1 big. Was 10 years ago and i hardly remember the setup. Think we just changed a switch to bridge and used another nl4 outlet allready there in bridge mode? Now doing it on a serial load is new to me! Reducing cable resistance part is amazing. But serial connection of speakers is + - + -.. you do it + - - + but with a bridged amp? You gotta open each box and redo them and always run them like this? Seems unflexible but its cool if its a fixed setup i guess! Im a bit confused by the jumping the negatives part.. honestly. And when you compare it to a balanced line or mic im even more confused. Cause those are polarity switched a 2nd time to make them in phase again and double the audio signal while cancelling the noise. And now you dont flip it back. Claim it to be nulled between the speakers as in cancelled.. but the spealers themselves still run in phase and aid eachother? It might be that its 4.30 in dubai but i feel im missing some piece of logic here. Haha im sorry. If you can set me straight id be happy! Love!

I sure would love to see Dave put out a video telling stories from when he did sound for Black Flag!

Hell yeah, ive never thought about it this way, i need to go rewire my amps coz im losing so much free power! My amp has bridge mode which requires only input into channel A, how would I get both left and right outputs into my subs since my processor doesn't have a mono sub out?

very interesting - so is there a way to bridge an already bridged amp, like hooking them up in parallel?

Would the bridged configuration be appropriate for a marble rye?

Got two 18inch 8ohms subs in two enclosures wired parallel to 4ohms. Amp runs in bridge mono but when connected to the speakers the load is 1.2 ohms is that right am new to this stuff

Im running a very powerful sub on an amp bridge as we speak but impedance is too low so amp does get very hot thank goodness i dont go more the 1/4 volume but yeah saving up to upgrade to a 4ohm stable amp to bridge and use cause this sub requires up to 3000watts to really get bumping.

12:24 Maybe I got something wrong here, but if you use a transistor amplifier, it's output is dependent on its load. So at generally speaking at a forum load it will make more power than it will at an 8 ohm load. I know that tube amplifiers have a different apology especially when they use Transformers for their outputs and therefore does not follow the same methodology as in car audio amplifiers where say running at a 2 ohm load will make vastly more power than running at an 8 ohm load. car audio amplifiers are often designed to double their output power generally going to a lower ohm load. (4 to 2 ohms for instance) I'll double-check this with the guys audio science review but as far as I know I believe this is the logic behind the different topologies. ============= *a word about resistance in speaker cables* from my understanding it seems that if you run higher frequency signals, say a 400 Hertz you're not going to get the same amount of resistance that you would when you're running lower frequency content. the cable Still Remains the Same amount of resistance per a given length and gauge of wire. however you may experience some top-end roll-off due to the higher impedance of the high-frequency monitors especially running in an active situation where a passive crossover is not used on the main high-frequency monitors. (this is usually never the case and Pro Audio since most Pro Audio gear automatically includes a minimum of a 2-way crossover generally to protect the high-frequency transducers) basically I'm not sure how you're getting more power out of a transistor amplifier when running at a higher ohm load since generally they produce less power as the ohm rating that the amplifier actually sees Rises . again I want to reiterate that on tube gear because of the topology and that many of them are running a Transformer it doesn't work the same way from my recollection in fact I believe you have to use different Taps on a transformer for the different ohm loads. *ABOUT WHAT AMPS CAN BE BRIDGED* (Big thanks to BareVids in the U.K.) half Bridge designs can be bridged to Mono however I don't believe that you can actually do this on a full Bridge. these are the typical and again forgive me bear if it's for doing this but this is more typical of Brazilian style amplifiers that use a full Bridge topology or circuit design. *HOWEVER* by taking two amplifiers of a fullbride, and then doing as prescribed I'm wondering if this is even possible ? for my basic understanding I believe you actually get less power even though it may actually work in practice but for my understanding from the amplifier design he would only be running one half side of the amplifiers mosfets again in a typical transistor amplifier. since most amplifiers are based on a Class D design due to its efficiency, and usually use a half Bridge due to the Simplicity of the design, ( ahem, cost-effective manufacturing of mass-produced items) it might be a better idea just to internally Bridge a single amplifier then using two separate amplifier modules as finding two that are uniquely balanced and setting up the games on each amplifier can be a crazy amount of work especially if you're dealing with multiple amplifiers in a live production environment. and I think you're also giving up some of the built-in protections for your speakers and your amplifier if you're using this method described but again I'm not a wizard on the subject it's just something to take aim to mind. still, it's a great tool to use when you have limited resources and limited budget and you want to get the maximum out of your equipment that you have on hand. so it's definitely a worthwhile trip. on a side note the only thing that puzzles me about Pro Audio is I wonder why the amplifiers themselves even bother on Class D designs to use inductors especially for low frequency transducers and content since those are usually filtered passively by the speaker itself since _generally_ the carrier wave is (Mostly) inaudible on low-frequency drivers. I think this would increase the efficiency but I don't believe it would result in a higher output generally since the main inductor is the voice coil on the subwoofer itself. I don't think people in the neighborhood or your other equipment might like that very much since you're basically pushing a very high frequency signal down a wire that's probably not shielded but again that's a discussion for another time :-)

What about running bridged mono into parallel woofers at 4 ohms?

I keep hearing about "Balanced headphones" in my mind Balanced is an XLR (or TRS) connection at line or Mic level. I see where we're going here and I get how it's balanced and in a way and I see how that's been done in every consumer device with a headphone jack (except the iPhone) but I don't see how a 4 wire headphone cable on crazy audio file headphones is balanced because it seems like they're separating out the left and right speakers and amps on the output side to somehow avoid combining the grounds. Maybe I'm thinking of balanced as in Signal cancellation and not balanced as in flow?

Hi Dave, I noticed recently that Berhringer have released a 6,000watt amp, but it only has a 10amp, IEC input @ 240volts. I would expect the input to be more beefy than this - either a 20amp powercon or 32amp cefform. Is the claimed 6,000 watts rating therefore reliable, a complete lie, or am I missing something? Hope you provide some insights on this. Jonathan

What about damping factor when bridged?

This is similar to how the 240V stove circuit works in your house.

Probably a better education than paying for a Studio Engineering degree

One significant reason to bridge, ... especially feeding subs, is eliminating potential bus pumping within the power supply.

Dave why would it need to be connected in that way (input polarity reversed) why not just leave the inputs the same phase and connect the outputs in series, as if you were putting 2 batteries in series to double the voltage, IE you take the top plus and the bottom minus, and connect the 'middle' plus and minus to each other. As far as I was aware amps (at least some) all the bridged switch does is apply channel A to channel B on the inputs and connect this middle link at the outputs. If you look at pictures of amp terminals they tend to have the bridged option printed on the back as the outer minus and plus terminals. (images search etc) Cheers.

My friend blue out his speaker his thinkng.. was since the speaker can handle it but also had to lower its power the amp gave out..RocknRollFlat5

Okay I’m grinning, off course!

Woow!!

What blows the amp?.RocknRollFlat5

Si == does the electricity sent to the earth go to earth or transformer> are the electrons the ones on a path or are other electrons present if it goes back to power pole- and do electrons come from earth or do the appear intra-dimensionally...... -WTPOW

I love running amps in bridged mono because I can often get 3x the power into the same load

I want to be like Dave when I grow up

I get the feeling that amplifier damping factor is next...

No its not better, they sound horrible, bridge may increase the power but half the demping factor and struggles to handle low impedance speakers !

where did you gain your non-technical crap from.

You can't just bridge two amps if they weren't designed to be bridged in the first place, as it will most likely fry them both! And you should never connect two speakers in series, because speakers also have crossover networks which are not designed to be connected in series... Also some of the "math" presented is wrong... Some stereo amps have a bridge or BTL switch. Just stick to those. This is why you should never get any electronics advice on KZfaq, especially from a long haired tattooed dude...

These videos help keep the brain in the game while we’re locked down here in OZ. Your mis-matched in a box example was my suspicion with a particular company. All in bridge mode. One OO box in the rig always looked like it was fighting itself. Uneven extrusion. I often disconnected it and ran 3 of 4 boxes. Cheers Dave