Amp Hacks: Can you bridge any amplifier? Bridge mode and how to do it without a bridge mode switch 

Thanks!

I appreciate that!

Why not, as audio signals and power connections, are only electrical in nature, but running with multi-frequencies, instead of simpler electrical fixed frequency & higher fixed AC levels.. Audio in and of itself, is ONLY pure electricity circuits, without any changes to the frequencies involved, whereas audio signals are extremely complex with multiple frequencies that are sometimes acting in both directions upon any audio cable at any time. (Oh &) p.s: you have a new sub, from this 70 yr old (retired) Kiwi Industrial Electrician, who learnt all about audio in the 1950's & 1960's, before becoming a heavy industry electrician in 1980, building, installing & commissioning ultra large and complex Multi-Voltage Industrial switchboards up to & including 2,000 Amp 3ph metering boards, in the likes of our main freezing works, and other places such as the huge Wood Chipping Mill, of Southwood Exports located on the Invercargill / Bluff highway opposite the Ballance Agri-Nutrients Ltd location in Awarua, NZ I have also worked on 22,000 volt switchgear that was used & installed into the Tiwai Aluminium Smelter, during the 1980's, here at Tiwai Point, opposite Bluff Harbour, at the bottom end of the mainland, of the South Island of NZ, where I happen to be a lifetime member of the greater community. 🔌Plugged in I am, to multiple aspect surround sound, via (my own taught) old school Analogue techniques, that I invented/discovered, back in 1965 when attempting to repair an old Philips (made in Holland) reel-to-reel recorder/player that had it's own speaker outputs attached, which powered the case halves that were the speaker boxes which acted as the case lid, making the unit extremely portable, as if it was a suitcase, and not a Valve Amplified Magnetic Tape machine, of extremely old vintage, even back in the mid 1960's when it "failed" on me as I was cleaning one of the many rain & dust covered valves - after it had been thrown out, into our local community dump by someone who didn't want it as back then people tossed away nice things, if they weren't any value to fix, or keep.) Being the unit I was attempting to "make better" until I dropped a valve of (later discovered unknown value) onto the concrete floor of the shed I was allowed to use, on Dad's dairy farm. Thus in a round about way, when trying to fix that - I discovered a hidden channel, inside the tape's recordings, that I very quickly found and hence it took over my life, after that which means I have been "into" the remastering / re-recording musical and sound content, since at least 1963, until now, being some ?? (Let me use the PC's calculator...) Wow, I've been an audio sound technician and audio manufacturer, for the past 61 years, as against my Electrical Trade Cert, that I started to get in 1982, that awarded me the top electrical apprentice award, for Southland in 1985 (along with a "representation" trip to Hamilton's Fieldays event, in June 1986, in which 19 tertiary education students competed in what I (and the other 18 students also thought, that it was a mock competition - until we discovered on the last day there, that all 19 of us had "completed" the challenge, with barely 12 points between all of us. So they awarded one person an award certificate (but not the others), until I - the oldest there, complained to the staff who had arranged it all, that it wasn't fair on all the other 18 student apprentices, to have NOTHING to show their colleges, or their employers, for the time off, at NZ's very well known Agricultural show. I later discovered that they provided all other competitors, the same attendance cert, as I got. Nothing else, just a piece of parchment stating we had (individually) been there and gained the appropriate cert for winning / attending the show. Thus as far as AUDIO goes, I have made and sold many over the years since 1965, being mostly those that I hand-build myself, obtaining the load-outputs - direct off most amplifiers, although some newer (more expensive but way cheaper to manufacture) internally bridged thus completely floating outputs, that required the use of aux connected isolation 1:1 audio transformers, thus I needed toroidal types - to allow me to three wire the normal L/R & Ground into common mode every output grounded transformers, such that one channel could be split into two identical channels, each semi-isolated from the other, running four way speakers in the vehicles "main passenger/driver area, whilst also allowing me to create several OTHER hidden channels, until my 1996 Mitsi Delica 4wd VAN ended up getting placed 3rd overall, in the 2003 NZ National Sound Offs, after everyone else had competed, when as a result of me complaining that I hadn't been allowed to compete, purely because my van's interior had so many ad-hoc new & used speakers, tht I had pulled out of rubbish-dumped TV's and radios, as well as having some four channels of subwoofers, that they had "claimed" could NOT have been of any loudness, what with the piddly little 300 watt (cheapest) amp driving into all the (looked like) aux speakers, in the back of the "seated" van, which I "ran" during the sound SPL test, at 60% volume of the head unit, and barely half "loudness" on the 300W amp, - yet the SPL reading came back at 126 dB on the test run, to come back again as an official result of 126.3 with everything driven (along with all DC powered Lights and speaker powered Neon's & LED's etc, that I had by then discovered were good for twofold reasons, firstly they "acted" as visual VU meters, allowing me to set various speaker volumes as needed, as well as by-passing the DC components of any "clipping" that the amp did, thereby protecting the speaker/s that they were parallel connected onto. The crowd, who had started to disperse, when this old fart and his muddy van insisted on being allowed to "compete", in that affair? Laughed loudly at my insistence of leaving the rear hatch door opened up wide, along with the sliding door open, and both front doors, plus I had every window open, to avoid any glass from shattering, if the SPL got too high, even though I had been operating the vehicle for several months on "roughly" the same power settings, when travelling - so the laughter continued, until I did the test run. There was the "obligatory" silence, while the "test" and then a proper run was completed, after which - the silence became deafening. Until I realised that the crowd wasn't laughing any more. Most there, who had been trying / vying for placements, as well as the youngster who won (in a wee two door sports car fully fitted out as if just a speaker enclosure anyway, ran up a lovely 128+ dB as his car shock apart with JUST BASS & lots of rattles), Had stopped their derogatory remarks, and were crowding around my van traying to figure out WHY it was so loud, when it simply looked (for all the world), to be a farmers hack vehicle, that had a LOT of various speakers of all shapes and sizes, tossed carelessly around it's interior and on the many seats, to then hear enquiries of "how many" are in there, (twenty five I told them), whereupon the organisers who themselves were gob-smacked, insisted I try again, with everything shut, but I just said, no, I want a run without any of the subwoofers running, to which I again got a LOT of loud laughter, and then the silence as I ran the system WITHOUT the four channels of subwoofers, or any of the speaker lights, whereupon the Mid's and Uppers/Tweeters, etc., told of a true test result, that of barely a 0.3 dB droop in SPL, at 126dB. I thus earned myself THIRD PLACE - against the two most expensive vehicle fitouts there, with a "lot" of others who had spent up large, buying huge amplifiers and big subs and had kitted out their vehicles so nicely, who hadn't even touched the 11o dB level of the 4th placed contestant, There were even those with just one 12" speaker in an otherwise empty boot, who hadn't even broken the 90dB levels, who (for want of a better description) were wishing they hadn't spent a cent on "improvements".!!!! Some people were outright angry, that someone in a work vehicle, muddy exterior and an old fart to boot, had effectively blown them away, with wht=at they had later learned, was a fully balanced 7.3 surround sound system with a super reverberation device, in the middle back area, being an old Fountain Speaker house cabinet, that had what appeared to only be one 600W speaker atop of, but which I then explained to those asking, that it was in fact, the original Fountain 12" 8ohm all purpose house speaker, with an inverted 4ohm Car Audio 12" speaker HARD BOLTED, directly over the top, with both speakers effectively SEALED as if one one diaphragm, with the top speaker inverse wired in series with the bottom house speaker, such that they BOTH moved up & down together with any lower than low, bass and super subwoofer reverberations developing within that huge sealed (non ported) cabinet, laying as it was, on it's back thus "bouncing" the vehicle up and down too, when it was being hard driven... Yet, without ANY of the four bass subwoofers running, during the second "quality of sound" test that they had (literally) urged me to do, which I had thus insisted to be run without any subs, knowing full well how well everything else sounded anyway, . I thus earned several "general" enquiries as to my abilities, and thus found several people who were delighted in being able to "booking me" for their house installs, which I gladly undertook. As I was told later, by my own Dad, not bad for a country lad.

I have an "electrical question" for the "other" Sparkie - in the room . How many phases (I call them audio channels, but as an electrician they are better described as "extra phases"), are there, in a basic domestic electricity supply network, where some are sent into commercial and heavy industry buildings, that run (or attempt to run) motors up to and including approx. 12 "channels/phases" that some bright spark called them as: Motor Poles. How many "different" phasings, can you get, out of the bog standard 3 phase 240v/400v Mains supply? If I put my mind to it, I can get upwards of 300audio channels, out of a simple 2 into 300 unit, that only has the basic two speaker input terminals, and just a 3.5mm output and six RCA sockets. ie: Check this out. 300 possible "speaker channels", derived from just a 2ch. sound supply "amp". ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lp6KxU4Bv1g.html

Glad it was helpful!

Thanks! Glad it was helpful!

Thanks! Haha... that's awesome.

Glad it helped!

Glad it was helpful!

Glad you liked it

Thank you, glad you enjoyed it.

Thanks!

Thank you so much!

Thanks!

That receiver is rated at 125 watts per channel, with seven channels. I don't know if you're using all those surround sound channels, but I would suspect that that is plenty of power for a typical home AV system with reasonably efficient speakers. If that doesn't get loud enough for you I question if you're going to be able to get to where you want to be by bridging. Home AV receivers usually are not as easy to bridge as a pro-sound amp, because they use unbalanced inputs. Going from 125 watts up to 350 watts isn't much more than about 3db (2x power), and a 3db change in level doesn't sound like a very big change in volume to our ears. So, if you want to make a big jump in perceived volume level you need to do a giant jump in power. Takes about 10 times the power to double the perceived output level.

Thanks for the comment. Maybe I don't understand exactly what your plans are, but I generally would not recommend connecting amplifier outputs together in parallel. Connecting loudspeakers together in parallel to one amplifier output is common practice.

Equipment may vary, but no, if the amplifier has a bridge switch I would expect that to take care of the input connections.

The A520 is a nice amp, but I don't think it's really intended to be bridged, that might be asking a lot of that unit. If you wanted to do so, you'd have to use an external bridge module to invert one of the input signals. For me, I'd rather listen to it in stereo. Your loudspeaker is rated for 8 ohms, and that should be about the "typical" load it presents with audio input. An AC signal. The speaker load will vary somewhat depending upon what frequency the input signal is. Some 8-ohm speakers can be as high as 30 ohms at certain input frequencies (around resonance) or maybe as low as 5 or 6 ohms at other frequencies. Speakers are a dynamic load. Measuring a speaker with a ohm-meter using DC isn't going to give you the full picture, and it's not uncommon for a 8-ohm speaker to measure 5-6 ohms (or 8 ohms) on DC. If the DC measurement is wildly off, like 50+ ohms, or a 1-ohm near-dead short, then I'd consider that suspicious. Cheers! Thanks for watching!

@@Barry-Watson thanks for the quick reply! I did measure the impedance and it measures at 5 ohms as stated on the website! I'm thinking I'm going to use the amp on my Pioneer vsx 422k hdmi ARC as it's very gutless. But the Yamaha A-520 with my realistic 15 inch drivers used to vibrate light fittings and the doors,windows etc. It seemed like they meant for each other! I have a home subwoofer amplifier with a 10 inch sub. I am going to install a better module. Cheers 🙂

When bridging a power amplifier you connect your loudspeaker load to the two positive (red) output speaker terminals, and leave the grounds disconnected. And, no, there is no need to run a wire between the two ground terminals since they are already internally connected. There might be some oddball amplifier that's an exception to this, but this is the typical setup.

@@Barry-Watson Makes sense, thanks.

Thanks for the question. You could get adapter cables that apply the audio signal to pin two of the xlr connector and ground to pin one and three. That will drive a signal into the amplifier. The problem with this is that it's unbalanced, so it could pick up hum and noise, and it doesn't accommodate the difference in typical signal levels between Pro Sound and Hifi equipment. The hifi equipment may not be able to drive enough signal into the prosound amplifier to drive it to full output. The pro sound equipment also has a low impedance input, which may be difficult for the hifi equipment to drive, or cause the hifi equipment to have poorer signal quality because of the excessive load applied. The proper solution is an interface box that converts unbalanced hifi level signals to balanced pro-sound level signals. This will preserve the signal quality, and allow you to make the most of your power amplifier. Here is an example of such an interface box: amzn.to/3QYWaHC ART CLEANBox Pro Dual Channel Level Converter This particular unit can convert signals in both directions, hi-fi to prosound and prosound to hi-fi.

You may find this video helpful: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HP4iDvEaonM.html

I'd think that sort of thing would be easy to find. Here's a BT amp module that's inexpensive from Amazon: amzn.to/3Qiz6Bl

Thanks -- Usually a "mono" switch implies bridge-mono mode, but some amplifiers offer a mono mode that simply routes an input signal to both sides of the amp. You'll have to check the documentation for your equipment to be sure. If it's a bridge-mono mode, it will likely direct you to connect the load to the + output terminals.

When you were running the crown amplifier in stereo, and it wasn't loud enough, did you actually see the clipping lights blinking? If not, chances are your receiver doesn't drive a strong enough signal into that amplifier. Pro sound equipment expects higher signal levels than hifi equipment. If this is the case, check out my other video about connecting prosound amplifiers to hi fi gear, I discussed methods of properly connecting equipment so you get full performance out of the pro sound gear. If the clipping lights were hitting, then you need more power. Bridging the amplifier might be a possible solution for you. You could parallel the speakers, connecting the plus terminals together, and the minus terminals together, and then both of those leads to the two positive output terminals on the amplifier. If the drivers are 8 ohms, two of them in parallel would be four ohms. 4 Ohms on a bridge amplifier is a pretty heavy load, I don't like it, but I suspect the crown amplifier can deal with it without overheating and failing. If you want to be nicer to your amplifier, wire the speakers in series. Connect a wire between the negative terminal of one speaker and the positive of the other, then take two wires off of the two remaining terminals (the unused connector on each speaker) and connect those two to the positive outputs of the amplifier. This will be a 16 ohm load, two 8 ohm drivers in series make 16 ohms. The problem with this, is it takes more voltage to deliver a watt, so this configuration will play quieter, and you may not be able to get the same amount of power out of the amplifier in this 16 ohm setup. Good luck, and best wishes

@@Barry-Watson Excellent, that is what I thought, thank you! Yes, I was quite surprised that the Pre-Out of the tube Class 'A' Ayon was apparently so low going to the Crown. While my Ayon was getting fixed from my bonehead screwing it up (thankfully a very experienced fellow nearby in San Diego did a beautiful job in fixing it for only about $275 - Ayon's Arizona rep quoted me a minimum of $800 just to look at it, Dumb@sses!) I had a chance to score another great barely used Cronus Magnum III all tube integrated amp for about $2000 (retails for $3500!) The Cronus is rated at an amazing 100 wpc which is huge for an all tube amp (it uses larger output tubes - The Ayon uses all KT88's rated at 50-60 wpc) and it did indeed have more 'punch', although I THINK it is not quite as 'spatial' as the Ayon. So, when the Ayon was getting fixed Interestingly I noticed that the Cronus has both direct and variable outs, with the direct Pre-Out being similar to the Ayon. So, when I used the Cronus the same way, the output was quite a bit higher, although I still left the dipole woofers bridged with the Crown. I wonder why the Ayon's output was a LOT lower...? Using the direct Pre-Out of both I can't see why that would be different. And yes, to answer your question, the power output lights on the Crown were BARELY moving even with the potentiometers wide open. Anyway, it's not like I'm going to be driving them at ear shattering volumes 😁 but, I think I do need the extra 'bump' just to be sure I'm getting enough for the lows. I know about the 'series' wiring. As a matter of fact in order to get the ohmage somewhat manageable with 13 drivers a side on the line arrays, I had to wire the drivers Series/Parallel in groups of 4 (3 sets of full range with one lone ribbon tweeter with a single capacitor as the only 'crossover' with all others running full range) So, the 4 smaller drivers in Series and then each group wired parallel, so it worked out to somewhere roughly around 6.x ohms a side. I'm kind of thinking that wiring the woofers in Series at 16 ohms might kind of defeat what I'm trying to do. The Crown I guess is rated down to even 2 ohms bridged, and like I say I'm really not planning on driving them that hard. I just need the headroom to go down as low as possible with enough power. I bet you would be VERY surprised at how low these go even though they are on open dipole baffles 😊 Thanks again SO much for your help, please keep up the great videos for us! 👍

Okay, if the amplifier's signal lights are barely starting to blink, you're hardly even turning it on. The standard signal levels of hi-fi gear, versus pro audio gear are typically 10db or more apart. That's a pretty significant difference. To accommodate that, I would suggest putting a signal converter box between your preamplifier and the pro sound power amp that converts the signal from unbalanced (RCA pin) to balanced (3-pin XLR), and boosts the level. Then you should be able to crank up the amp, and get it to drive to full power. I would bet the amplifier has ample power for your application, and there's no need to run in bridge mode, which provides lower performance in every way except for output power. Consider something like this: amzn.to/46Y3GJ6 Be sure to grab a couple of XLR patch cords, male one end, female the other if you need them to go from the interface box into the amplifier. if you like the fancy stuff, here are some nice ones: amzn.to/3QDbSbN Videos: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ShT8mWo_P1g.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HP4iDvEaonM.html Cheers!

@@Barry-Watson Yes, I saw that you had alluded to that earlier, I just was not familiar with that conversion between the types of equipment. Even now with it bridged, I still have to crank up the Crown to about maybe 2 or 3 positions back from full. But, I will look into what you are suggesting. It's just that being an 'Audiophile' I kind of hate to introduce anything into the signal chain that I don't have to (thus the 12 full range drivers a side with only one capacitor on the ribbon tweeter - and, of course absolutely NO EQ ever! 😊) But, I'll check it out. It's not like the Crown is the pinnacle of 'Audiophile' equipment anyway, I originally chose it simply because I just wanted something fairly well spoken of that was powerful enough to drive the 2-15" dipole woofers. But, at that time I was using SS amps for the line arrays and there wasn't that disparity. Also there was a 'Tape Out' from the amps I was using to go to the Crown that apparently is at full throttle which was plenty. That disparity in output from the Ayon sure is a weird one, but I see that you are familiar with that phenomenon happening between the two different types of equipment. I wonder if I should just look for some other kind of 'Audiophile' amp (I keep putting that in parentheses because I know it can be a bit pretentious) I wonder if I just looked for some mid-level affordable 'Hi Fi' amp to drive just the woofers if it would 'Sync' better power wise with the Ayon...? Thanks again for the excellent help and suggestions!

Well, I find it a little bit amusing that you would consider bridging the amplifier, and feeding it single ended, with all of the sonic problems associated with that, but you're worried about the sound of a conversion box using modern op amps - haha. Furthermore, we're talking about the subwoofers, so you'd probably never hear any minor artifacts down there anyway. Personally, I wouldn't bridge an amplifier unless it was absolutely necessary. Convert the signal properly, if you want the equipment to work like it's supposed to. Do not feed unbalanced signals into a pro-power amp, that is not a good way to do things if you want decent sound quality. So find a unbalanced to balanced signal converter, like that ART clean box, and that's the answer to this issue. Drop the $150, and I think you'll be very happy. There are other manufacturers who make these kind of conversion boxes -go for one from a respected brand (like ART). Just avoid the supercheap $20 no-name versions. I've been down your path. For me, I think it's a path of religion. After spending many thousands of dollars on fancy shiny hi-fi equipment when I was younger, I started sliding more toward the Pro Sound world where real performance was delivered. Now, i'm not saying to go buy no name cheap junk and say that it will sound great. But I do believe that professional gear marketed at the commercial industries will almost always outperform all of that overhyped, overpriced, over shiny hi-fi junk that pipe smokers fawn over. I go for equipment designed by real engineers, using real science, and real measurements and used by professionals who demand real measurable performance, and know what it actually is. There's a lot of religion and hype in the sound industry. Don't believe the hype. And... keep exploring! PS - There are some minor differences in electronic equipment, but let's get real, top quality audio gear these days sounds really really good, just about all of it. You're not going to hear a major difference between different brands of amplifiers and processing gear 99.8% of the time. You WILL hear a big difference in loudspeakers, that's where to focus the attention.

Thanks for watching! With unbalanced inputs you're not going to bridge using a simple cable hack. You need to invert the polarity of one of the input signals before it reaches the amplifier, and the best way to do that is with some active electronics. A simple line-level amplifier stage. I don't think you're going to get impressive gains by bridging this amplifier so overall I would advise against it. But if you really want to explore this, a possible solution would be to get an amplifier unit like an art clean box that converts unbalanced input to balanced outputs. You could then wire up some cables from the output of that converter box. Bridging creates a mono amplifier, so there's only one amp input so you'll only use one channel on the converter box. On the xlr output of the converter box, connect your rca cable grounds to pin 1 of the XLR (ground), connect RCA signal (L+R) to pins 2 and 3 of the XLR Connector. XLR pin 2 is signal positive, and pin 3 is signal negative. ART converter box amzn.to/3I8BgRD XLR (F) connector you'll need to solder your RCA cables to. amzn.to/3IaMIwk

I'd probably use it as a stereo amp.

I'm using the nad c352 as a preamp with the Rotel rb981 poweramp right now. The c370 is adequate as a standalone amp; but would still like to experiment a bit further.

So if you plug a signal into the other inputs (Tuner/Aux etc) you get stereo, but one side of the phono inputs is dead? Sounds like the main preamp is working. The phono inputs have a transistor gain stage and RIAA EQ for handling a phono cartridge. It's a fairly simple preamp, but you'd have to tear into it to discover the bad connection or failed component.

Sorry i've been really tied up i did check my EQ, ashley combo cd cassette player and I can plug my iphone into the left/Right input on the front on the crown IC150a all works fine. I believe the preamp is producing stereo even though i'm running the two D75s in bridged mono. with each amp set to mono. I have this system in a rack , meaning i have to pull out components to gain access to the back of the preamp. that process is complete and i can clearly see the to small adjustment pots are nowhere set the same. looks like left at 12:00 and the right set at 3:00. This leads me to next question. I do some tube amp mods where i will install an additional power tube biasing pot. This allows for adjustment of two bank of two and the adjust the the two banks to be compliant with the with the desired setting providing a congruent push pull from bank to bank. Finally the question the recommended setting on the phono inputs is 47K ohms. does that mean meter the rca inputs Outside shield to inside signal post and adjust each pot to 47K?

Sounds like there is a defective phono pre-amp (on one side). I don't think the connected power amps (D75s) matter in this equation (that's all working). The input should look like appx 47k load to the phono cartridge, and the level pots shouldn't affect that. It's curious that the two level pots on the rear are set at vastly different positions, I'd call that a sign. I'd first try adjusting those pots to see if you can get both channels working and at the same output level. You *might just have a defective adjustment pot, or you might have a bad semiconductor in the phono stage (I think it has a FET transistor), or a failed coupling capacitor or broken connection or something. It's not a really complicated circuit. Option B is to ignore the bad phono section, get a little external phono preamp (with the proper RIAA EQ) and connect it to one of the AUX inputs, and be happy. amzn.to/3PRg8B1

@@Barry-Watson Thank you, all really good info. I think that im going pull the cover off the IC150a Ring it out with my meter first. If that doesn't produce a quick and simple repair, I'll take your advice and purchase the phono preamp suggested and attach it inside the rack, strain relief the cabling and call it good. I was thinking about probing it with my Oscilloscope but decided way to much hassle. You have really helped out a ton. I understand guitar tube amps but when the transistor came on the scene i just never really became interested in the technology. I'm a analog dude the love playing guitar and have figured out how to get the tone i like and can repair/voice tube amp for others. once i get the time to get it done i will share the results.

Good luck. If you decide to dig in, I think you can find the schematic on the Crown website. If you can't find one, let me know, and I can send you a copy.

I'm not an expert on that amp. I think it's rated at 50 watts. Even bridged, I don't think you're going to see a "lot" of power. Instead of buying 3 of those A2s, I think just getting a larger pro-audio amp(s) would offer more power at a lower cost.

@@Barry-Watson the basx A2 is rated at 160 RMS at 8 ohms per channel and 250 RMS at 4 ohms per channel but that all I know for sure,thanks for replying

Thanks for the correction! I'd start by seeing if the amplifier has a common ground (0 ohms measured between the 2 negative (-) speaker terminals). If so, it's likely you could run the amp bridged into a 8 ohm load. I'd check to make sure it doesn't get overly hot.

@@Barry-Watson thanks wen I run it normally it doesn't get hot at all it's actually cool to the touch

Good question, I have not done it. Seems to me it would be the exact same thing, invert one input. The issue with tube amps is that they have output transformers, so I'd be careful to be aware of the current limits to not damage the transformers. The transformers would need a common ground, so check if both sides (L/R) are floating relative to chassis ground or each other (using a ohm-meter). You might need to connect the (-) output sides together. When I think of bridging amps, it's a tradeoff of some sound quality for a bit more power. Tube amps to me are all about sound quality or maybe character, so bridging a tube amp, to me, probably isn't something I'd pursue. But, hey, if it works for you, it works. If you discover anything interesting in the journey, please feel free to give us an update.

I really wouldn't recommend that.

@@Barry-Watson why’s that?

First, bridging the amplifier probably isn't going to give you that much advantage anyway. For me, the juice is rarely worth the squeeze when it comes to bridging amplifiers. You may gain a little power, but you lose audio performance in every other category. But bridging across two different amplifiers could invite issues when tying the grounds together between the units possibly, and any little differences in gain between the amplifiers would result in poorer performance. Technically, it could be done, but it just doesn't seem like a great idea to me. They way I see it... If the amplifiers aren't powerful enough when working as designed (w/o bridge), the best solution would probably be to swap these out for a bigger unit that can deliver the performance you're looking for.

@@Barry-Watson thank you for the information

I wouldn't do it while the amplifier is running, since it may create a transient pop that wouldn't be good for the attached speakers. The bridge switch just swaps the polarity of one of the channels and usually connects left input to both channels, so no, that won't hurt anything except for your stereo image. If the speakers were wired normally, in stereo , and the amp is in bridge mode you'd have one speaker pushing outward while the other one is pulling inward. That wouldn't be very useful, but it wouldn't damage equipment.

I'm not sure I understand the question - can you describe your setup. If you're powering equipment, it's a matter of how much load your transformer can accommodate without overheating. The transformers out on the power lines drive multiple amps, lights, and all kinds of stuff.

@@Barry-Watson i have a two amplifier a gemini 5000 and a Behringer nu6000 but the Behringer has power issues it keeps going into protection mode even with stable power going into the amp so I wonder if I could change the power source going into the Behringer for a better result?

A big amp can draw some really high peak current. This is why portable power generators that seem to be rated with enough watts may struggle to power a band show. They can handle the average power, but can't deliver the necessary peak current. I never had trouble with the big trailer mounted commercial diesel generators, but anything smaller would give me a nervous night. Two big amps, like iNuke 6000s, if pushed really hard could overload a typical 15amp power circuit. Some of the class-D amps in particular can really hit the line power hard with peak current demands. Some of the old-school (heavy) AB class amps had massive power supplies with huge capacitors that helped buffer some of the peak current demand draw. I'd try plugging your rig into a really solid power supply (a 20 amp circuit without any other big loads on it), and see if you have any issues. If not, you know you're just not delivering the power that's demanded. This is assuming it's tripping protection when things are pushed real hard. If the amp is going into protection when idle, or when the levels are low, then there is something wrong with the load (speakers) or the amplifier.

Ok thanks

Possible, but not easy, and I would say not worth it. I would question if a typical integrated amplifier is stout enough to handle being operated in bridge mode reliably. You need to invert the polarity of one of the inputs and then feed the same signal into left and right, and attach the loudspeaker to the positive output terminals. A typical hifi amplifier uses unbalanced inputs, that is a signal line and a ground. So to invert the signal, you actually need some active electronics, a small buffer amplifier to do that job that sends the proper signals to your amplifier. You could build such a thing out of an op- amp and a few parts, but offhand, I can't think of a retail adapter product that you can just buy to easily do this. Bridging the amp converts your stereo amplifier to mono and reduces the performance a little bit in almost every way, except for the power output. Often the power gains aren't that great. In a lot of instances, especially with smaller amplifiers, I just don't think the juice is worth the squeeze IMHO, and rarely would I want to give up a stereo amplifier for mono.

@@Barry-Watson yes i thouth so. It would be very difficult to bridge an integrated amp. I asked b'cos that's the only amp i have. But just incase, i'll have the budget soon and would buy a power amp, how many watts would be recommended for a (Live brand) speaker 18in double magnet 1000watts ? That's the speaker i used for my subwoofer right now. (I have 2 single speaker subwoofer box). Thanks..

It takes a big difference in watts to really make a difference in loudness so I think anything around 500-1000 watts to the sub would suffice, especially for home use. Maybe your box could handle a little more power than this, but going much bigger with the amplifier will probably not make a big audible difference but will be more risky to your speaker and your wallet. Lots of good larger power amps to choose from. The Behringer EP4000 is a traditional, heavy, reliable power amp that offers good value in this power range, It is suspiciously similar to a QSC 2450 which is also an excellent amplifier. I'd look for something about that size. The lightweight, digital amplifiers are nice if you have to move them around a lot. Since you mentioned budget, I wouldn't be afraid to check out used gear that's in good working condition. If I had to choose within a budget, I would prefer a nice used Crown, QSC, Crest etc or other respected brand over a new unknown-brand imported low cost amplifier.

@@Barry-Watson very well said. Thank you so much for your time to reply. I appreciate.

You're welcome! Good luck!

That would be a good topic for a video!

A typical power amplifier would be a stereo device, it has two speaker outputs, for the left and right speakers. The left, and the right sides of the amp are totally independent and could be playing different material from each other. So, we have two independent amplifiers in one box, in a stereo amp, it's two channels. A 4 channel amp, would be one box, with four unique independent loudspeaker outputs, (and four inputs). Essentially, it would be like two stereo power amplifiers, all contained in one box. For example, you may see a four channel car stereo amp. Channels one and two could drive the front speakers, 3 and 4 could drive the rear speakers. A home AV receiver is usually a multi channel amplifier. It's not uncommon to see five or more channels of amplifier in an AV receiver, to drive front speakers, rear speakers, center channel speaker, and subwoofers. Each of these speakers need independent signals, and a separate amplifier module. Cheers!

Ha! Yeah, I'd think that would be enough.

Requires two amplifiers and a common ground to bridge.

Thanks, sounds like that would be a solution for driving difficult loads.

@@Barry-Watson Ya if you had a difficult load you could just use a Y connector on the inputs of a stereo amp (do NOT invert 1 channel as in serial bridging) and connect the outputs in parallel to 1 "difficult" (Mono) load, you should get double the power into half the impedance of what one channel on the amp is capable of. Of course you would need 2 amps for stereo. It is important that both channels in the amp get the exact same signal and level, thus the Y connector. Also if the amp has gain controls they have to be set exactly the same.

This is how I have to bridge my peavey IPR3000 DSP. Parallel the inputs, both channels turned up full, DSP settings set the same, channel A 1+ and channel B 1-. Does rather well powering (2) 8ohm subs night after night

Typically + is carried on a red wire, and - is black. Internally this is likely a bridged amp (already) and the outputs don't share a common ground.