Risks and Drawbacks of Bridging Audio Amplifiers

Tech Tip: Why I think running audio power amplifiers in BRIDGE MONO mode is not a wise idea.

[@slyspy9819]

Thanks Barry , A common sense no nonsense look at a practice that's proving to be unnecessary. I learned something today ...Thx

[@Barry-Watson]

Glad it helped!

[@bubbabitowang9713]

I just want to thank you. I've always shared this same opinion based on my own observations but never knew the nuts and bolts of it. Thanks to you I have a better understanding.

[@Barry-Watson]

Glad to help

[@jblcontrol28crossover76]

Wattage output specs are largely a function of how they are being measured/determined. An amplifier that can provide a maximum of 100 watts output continuous sine wave is also capable of providing well over that figure for an instantaneous burst. The burst output may even be greater then the mains power wattage being supplied to the amp because a well designed amp will include large capacitors in the power supply section that can store up power and deliver it on demand. Remember, standard audio signals being fed into an amplifier are enormously dynamic. Even with highly compressed signal, the difference between average signal level and peak transient level can be 3:1, 5:1 or higher. Output can exceed input because it's not occurring continuously. The following is my poor attempt at a car analogy... We can have a 100 horse power motor spin up a large flywheel and then when we dump the clutch, the flywheel can deliver 300 horse power to the tires for an instant. Where did that extra 200 horse power come from? It was stored up over time and when released, delivered for an instant.

[@howardskeivys4184]

Excellent advice in my opinion and meticulously explained. The voice of common sense in what can, all to often, be an elitist world!

[@Sonicsnd888]

Thank you for your experience & time spent .Excellent

[@Barry-Watson]

Glad you enjoyed it!

[@eugenecummings1]

Thanks. I learned several things today!

[@Barry-Watson]

Thanks! Glad to hear it!

[@isiahgreen8405]

Thanks Barry. Good Info

[@kwacz]

Very good presentation. I remember years ago when i first learned all this. I was in complete disbelief because it goes against what most people think. But the information is all accurate.

[@Barry-Watson]

Thanks for sharing!

[@bassiclogic]

Great video! Thank you!

[@roofermarc1]

I’m glad I found this. This is the best explanation of a bridged amp I’ve seen and now won’t be doing it. Thanks.

[@Barry-Watson]

Thanks! Some (big) amplifiers do have the current capacity and thermal abilities to easily handle running bridged into difficult loads, but for many it can be stressful. In an ideal world, it should offer up to +6db more output. I think it's often more practical if you're already running a fair amount of power to seek more efficient speakers rather than more raw power... if you need more output.

[@roofermarc1]

I have an Emotiva xpa 2 gen 1 and these are Bridgable is why I was thinking of getting another one if I could bridge and turn it into a monoblock?

[@danielantoniuk559]

Hi, Barry I liked what you had to say. Not often can I hear a full conversation about any audio topic where I feel the person is consistently correct. In your case, I find what you have to say as spot on. So thank you for contributing some good factual information that is based on sound knowledge and experience. That being said, you almost scared me into not bridging my little 8" woofer in my car stereo with my super high current 1 ohm stable amp. Well, like I said you almost scared me into not doing it lol. Well, I still agree with what you said but in my case I am working on a personal project using this Zapco Z100 C2 SL amp, a small but mighty high current 2 ch automobile amp to run a set of components and a little 8" sub in trimode. Supposdly this little power house can run as low a 2 ohms mono but I'll be doing it 4ohms mono on the sub to run it a little cooler. Once again thanks for the great post!

[@Barry-Watson]

Thanks! When speaking in general terms, somebody can usually find an exception. There are some amps that run just fine in bridge-mode, especially in car audio where this is more common. Hope your setup works well for you!

[@caprimen]

Very interesting , thank you - was just setting up wedding in barn and bridging two 500 watts amp with a split input , but will try just using one amp in stereo and think you are right about lower bass and clarity thank you

[@Barry-Watson]

Glad it was helpful!

[@69novaguy91]

Just when every over Bassed Head on KZbin is swearing by the BRIDGE YOUR AMPLIFIER BAND WAGON and rattling and contorting every body panel in their vehicles with a Bass level at a point of major annoyance to my ears and every bolt holding their cars together ..... Finally a Guy who actually is a sound engineer and knows what He is talking about to hopefully set the Record straight on how to actually set up your amplifier and Kill The " I am pushing a couple thousand Watts to my Subs Fairy Tale ..... Thanks Man great Video .... I spent years on the Road Lead Guitar, playing Loud and Fast Heavy and Hard Music ... Hauling Loads of P.A. Rigs and Marshall Stacks going through many Sound Men and found only a small Handful of Sound Guys who could actually Tweak and Mix the sound of a Live Performance correctly .... But when We found The Guy's who could Mix and set the sound properly .... IT WAS LIKE MAGIC !!!! Thanks for the Video and your Knowledge Cheers from Canada, Ontario

[@voxpathfinder15r]

Not to mention you have three 100 watt Marshall super lead stacks going full bore and realize a P/A system isn’t really helping them very much unless you’re up in the 30,000 watts range.

[@Barry-Watson]

Yeah, large stage volume where you have no level or EQ control can make it more challenging to achieve a good balanced mix for the audience. When it comes to level, just because you can, doesn't mean you always should. It is possible to chase patrons out of the room, I often leave a lot of watts in the box.

[@organfan668]

I’ve got an Adcom gfa5006 with four of its channels bridged to a pair of Klipsch r34c and notice a little bit of noise. I heard the same noise in my center being bridged with a small amp also, changed it to stereo and it’s almost completely gone. I haven’t tried just powering these front speakers at 50 watts but will.

[@valerecampbell130]

Verry good advice love it.

[@Barry-Watson]

Glad it was helpful!

[@o.g.solutions]

Great explanation! Subbed

[@Barry-Watson]

Thanks!

[@hailholyqueen]

Thanks for conveying the knowledge and the clear language without the all the expletives.

[@Barry-Watson]

My pleasure!

[@gregkirby]

Yes! Thank you!

[@marlonmolicara154]

Well said

[@ericnortan9012]

I use a Crown XLI 2500. 2 channel, AB, rated 500 wpm at 8 ohms. Plenty of power for my 15" Cerwin Vegas. Usually, I barely make the signal lights glow, but I have all the power in reserve I'll ever need. They rate them bridged at 1500w @ 8 ohms, can't see me needing to bridge them. My advice is get a properly sized amp for your needs. Buy actual monoblock amps.

[@subsonicdeathmonkey]

Thank you

[@rudeboysw9]

I've been running my amps in stereo 30 years plus.... my friend always bridges his amps and wonders why my rig sounds deeper with better sub\bass definition. no lower than 4ohms for me 2x18" scoops either side is enough for most venues sometimes I just run one 18" scoop but I agree never in bridge mode.

[@kenweipert7926]

does this apply to bridging two one channel monoblock amps? I am running a vmps sub with a marantz ma500 and need to address clipping from lfe in movies played on my home theater

[@Barry-Watson]

I think a better solution would be to use a amp with clip-limiting, or place a limiter in front of the amp with the threshold set to activate before clipping, to prevent the amp from being easily driven beyond full power. Bridging may give you a few more db of headroom, often if you're hitting clipping, you need more than just a few more db to be safe. A limiter can quickly catch those brief big transients and transparently control them.

[@andreisalads7499]

Watching from Pangasinan, Philippines God bless

[@Barry-Watson]

Awesome! Thank you!

[@simonamponsah5982]

Hello. my amplifier is having all the modes except, instead of parrallel mode is rather mono. Is mono mode the same as parrallel mode.

[@Barry-Watson]

Parallel mode is a mono mode. This is where you can connect both the left & right outputs together + to +, - to -. The input signal needs to be identical on both channels. (This setup might happen automatically for you when you switch the amp into this mode, depending upon model). The purpose of this mode is to allow the amplifier to drive difficult high-current loads with lower impedance than a single channel can normally drive. If you're driving a typical load (like 8-ohms) that a channel can normally handle, this mode will not offer additional power. I don't often see amplifiers used this way, probably most often used in car audio.

[@gabrielmease1169]

Thank you. Just what I was looking for. Any thoughts on bi-wire?

[@Barry-Watson]

Bi-Wire could mean simply adding a second speaker cable (same signal), in which case it's the same as using a thicker speaker wire... which is good, but there is a point of diminishing returns, especially if you're already using 12ga or 10ga wire over typical distances. If you're referring to bi-amplification using an active crossover (or amplifier DSP) and more than one amplifier where one speaker wire carries low/midrange signals, and the other wire carries high frequency signals for the horns/tweeters and you bypass the loudspeakers internal crossover, I generally support that and I feel that configuration often sounds somewhat better and eliminates power losses that happen in passive crossovers. Personally sometimes I do this, sometimes I don't depending upon which PA rig I choose. Often the sonic gains are not huge, and it requires more amplifiers, more equipment (heavier rack!) and adds a bit more complexity. I prefer active crossovers, but beware that the loudspeakers passive crossover may provide some driver protection, and possibly customization (eq & phase correction) for that speaker which should be programmed into your active crossover if you want the best performance. Active (powered) loudspeaker systems often implement the crossover before the amplifier stage and use separate amplifiers for the low & high frequency outputs, thus providing the benefits of a bi-amplified system, and tend to be correctly scaled or limited to reduce the chances of driver damage from overpowering & transients.

[@woabeatz9717]

@@Barry-Watson what about a bridgable amp?

[@Barry-Watson]

@@woabeatz9717 Sure, you'll get slightly poorer audio performance, but some amplifiers do have enough current and thermal performance to operate bridged just fine (into a reasonable load). And, some amplifier designs are a pair of internally bridged amps per channel... a common feature in car amplifiers, for example.

[@woabeatz9717]

@@Barry-Watson i ordered a lanzar vector... 2 channel for one 15 inch woofer bridge it or not..? Cheap pyle woofer...

[@Barry-Watson]

@@woabeatz9717 I haven't used that amp, so I cannot say, but most car audio amps are designed to be run bridged. So, I'd try running it bridged, and do that if it sounds good and doesn't get overly hot when driven hard.

[@joseorozco1416]

Thank you for your video! Barry, I have a 3k wts amp. Both can run 3k 4ohm bridge mode. Can this damage a pa speaker with a 1000 rms 4ohms? Or I just leave it at 2x 900W/ 4ohms per channel?

[@Barry-Watson]

You could probably damage that speaker in either case if you push things real hard. Use care, and don't push things to the limit, and I'd suspect you'll be fine. Putting a peak limiter before the amp might help prevent accidents.

[@joseorozco1416]

@@Barry-Watson .. a limiter of course. I have a dbx driverack I think that should cover it. Thank you so much 🤘

[@Barry-Watson]

Perfect!

[@frednimako]

Good day sir, I'd like to ask, how do you know your speakers are suffering from overload, even in stereo mode amp

[@Barry-Watson]

Sometimes it's hard to tell... until the speakers go quiet and smell bad. Sometimes you can hear the cones hitting xmax making a slapping sound, ouch. That's as far as they can mechanically travel. If you're a good listener you may notice the sound having a compressed character, or notice as you turn up volume the speakers don't get a whole lot louder. As the speaker approaches max output they usually have "power compression". It's a little bit like your car can only go so fast... even if you can push the pedal down a bit more, it just can't go any faster. If you see that behavior, that's probably a good time to back the levels down a bit. Fuses and light bulbs are often used to offer some protection to drivers. I have a video on that topic, as well as a video on speaker power handling in general. So, check out the other videos on the channel. Thanks!!

[@frednimako]

@@Barry-Watson thank you, will Che k those videos as well

[@jakesterfiddle]

Here are some counters to your arguments that I've heard and I'd like to get your opinion on: Obviously you shouldn't put more power into a speaker than it can handle. However when you say "If you put 3000 watts of power into any rational driver the voice coil will be toast," I know most mains speakers aren't designed to handle that kind of power but I've seen many dual 18" subwoofers that are rated for around 3000 watts program power. And when you say that a standard wall socket can output about 1800 watts, I'm assuming you're using 120V*15A=1800w which I totally agree with, but most circuit breakers won't trip unless something is pulling a ton of current for at least a second or two. Music is very dynamic though, and the massive volume peak of a kick drum for example might only last for 100ms or so. Plus, a lot of amplifiers are built with big capacitors so that they can store power for these temporary huge volume swings, and thus aren't directly pulling from the wall when those big hits occur. With "a bridged amplifier is working much harder than a non-bridged amp", I agree with that but most amplifiers these days are rated down to 2ohms per channel, so running an amp bridged at 4 ohms would be perfectly fine for it. Finally, the main think i'd like to get your opinion on: I've heard that it's really easy to damage both your amplifier and your speaker by driving your amplifier into clipping, and that even if a speaker is rated for much more wattage than the amplifier you're using, if the amplifier is being driven extremely hard into clipping, you could actually damage the voice coil of your speaker. So, in this case wouldn't it be safer to put your amp in bridged mode in order to have more headroom and not clip your amplifier, but still get the same volume?

[@Barry-Watson]

Good points, and I don't really disagree. I've seen speaker "systems" that are rated for 3000w+, usually some kind of "peak" spec, which may be a little dubious. I have not seen a single loudspeaker driver however that could take that kind of power RMS. There might be an exception, but if so I'd consider it exceptional. So much equipment these days is rated with a "peak" spec, and I think some of it is... a bit over-rated. A peak power spec may actually better represent real music, but often I think some of those numbers represent the marketing dept. Yup, amps have power supplies and the capacitors allow them to deliver brief peaks over the RMS mains power. True. With full range music, this may gain you a bit (peak to avg power ratio is typically high), in subwoofer duty (where you really need the power) the peak to avg power ratio isn't as severe, so the peak demands delivered by the power supply over the mains isn't as significant. If you think in terms of DB, the gains in terms of loudness really aren't going to be that great. Yeah, I also agree that as long as the load and the thermal dissipation is within the amps ability, bridge mode is perfectly safe. I'm just saying it's a lot easier to reach those limits in that mode. Clipping can be bad on loudspeakers. Primarily because clipping creates (usually odd-harmonic) distortion which has a lot of high frequency content, often far more than typical music, and this can easily overpower the HF drivers/tweeters, which are sized for the typical power needs of music (much more energy in bass then highs in typical music). Severe clipping also creates brief periods of DC (where the output wave goes flat at the top/bottom), this can be pretty rough on the woofers. I don't like to do it, but actually for a high quality rugged amp, clipping itself shouldn't be harmful to the amp as long as the situation isn't driving a heavy enough load to cause severe overheating. You're just switching the outputs up to full-on. Yes, some people say you'll damage speakers by "under-powering", that's not true. But you can break things by using a small amplifier pushed too hard into clipping, and you'd be "safer" with a bigger amp if you have the restraint to not push the bigger amp into clipping or way above what your drivers can endure. It is possible to push loudspeakers beyond the xmax (mechanical cone limits), and cause the cone to become misaligned and scrape, or to push enough power to melt voice coil wires. So, a bigger amp may be "safer", but you can always break things if you try hard enough ;) That's my opinion! Thanks for the comment.

[@jakesterfiddle]

@@Barry-Watson Thanks! I just invested in a full JBL SRX loudspeaker system. 2 SRX718s rated for 1600rms/3200prg/6400peak @4ohms each and 2 SRX812 rated for 800rms/1600prg/3200peak @8ohms. So I was thinking a bridged amp for each speaker would be the most cost-effective method to power these speakers to the full potential, as an amplifier that can put out close to 3000w/channel into 4 ohms is really freaking expensive.

[@jakesterfiddle]

Plus, I can plug each subwoofer amp into different wall outlets so I am less likely to blow a circuit

[@Barry-Watson]

JBL SRX is good stuff! Remember 1500 watts to 3000 watts is only 3db.

[@marklowe7431]

Love it. Reality breaks their world.

[@dandonna852]

thanks I was going to go with bridging not now. thanks

[@corbensmith9470]

I knew and understood this. Wasn't until I got back into car audio. With my old school system I had left which was a Cadence amplifier and a Kenwood. Primary used for 8in mids. Put 1amp for 12inch sub. Bridged. About 35% more out put. Absolutely was stressing the amps. Technically I was still underpowered so yeah I agree with your statement

[@thecheapaudioengineer]

I love to bridge amps.. in different way hear me out.. So i have a (700Watt rms@8ohm)*2 channel.. I bridged them and now running my 2*( 500watt rms 8 ohm) speakers in series.. In the end the rms power is the same.. i can say i have bridged my amps...😂😂 And there is one benefit.. i can skip out on wires 😂😂 No need for negetive wires for the speaker.. though i leave one a bit less thick one just for sake😂

[@justinsands1760]

the first 30 seconds were fucking amazing,, i got a 500watt amp, im gonna bridge it. idgaf what anyone says 😭😭 you dont need to bridge 3000 watts 😂😂😂😂😂😂😂

[@Barry-Watson]

Haha... I suppose that's true in the world of car audio. With PA/band systems, those kind of levels driving the woofers are not uncommon.

[@dougaltolan3017]

From the amp point of view there is no difference between bridged and a driver with half the impedance. If your amp can fully handle a lower impedance driver it has no trouble running bridged.

[@Barry-Watson]

Thanks! -- Good point! For safe operation, the minimum impedance of the loudspeaker load in bridged mode should be 2x the minimum impedance rated for stereo mode. Thus, if the amp is rated to safely drive a 4 ohm load in stereo, it should have a 8 ohm load (minimum) bridged.

[@HarryMonk01]

Thanks man, just convinced me not to try & blow up one of my amps...!!! 🤔😏😂🤣🥴🙂😂

[@Barry-Watson]

Thanks! Some amps have the current capacity and thermal dissipation to bridge without issue, but most of the time I prefer to avoid driving gear that hard. The gains vs benefits just aren't there for me.

[@snoopfurlow1275]

i accomplish it years ago .I won't reccomend bridging something that big.i will not do it again Its super dangerous..

[@chiefkicabich7312]

People with bridged amps have loose bottoms. Got it.

[@Barry-Watson]

Ha! Maybe. With some amps I can hear the difference.